api.md: add TOC

It's about to become a no-op in control.

Signed-off-by: David Anderson <danderson@tailscale.com>

.github/workflows/coverage.yml

@@ -0,0 +1,48 @@
+name: Code Coverage
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - '*'
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    if: "!contains(github.event.head_commit.message, '[ci skip]')"
+
+    steps:
+
+    - name: Set up Go
+      uses: actions/setup-go@v1
+      with:
+        go-version: 1.15
+      id: go
+
+    - name: Check out code into the Go module directory
+      uses: actions/checkout@v1
+
+      # https://markphelps.me/2019/11/speed-up-your-go-builds-with-actions-cache/
+    - name: Restore Cache
+      uses: actions/cache@preview
+      id: cache
+      with:
+        path: ~/go/pkg/mod
+        key: ${{ runner.os }}-${{ hashFiles('**/go.sum') }}
+
+    - name: Basic build
+      run: go build ./cmd/...
+
+    - name: Run tests on linux with coverage data
+      run: go test -race -coverprofile=coverage.txt -bench=. -benchtime=1x ./...
+
+    - name: coveralls.io
+      uses: shogo82148/actions-goveralls@v1
+      env:
+        COVERALLS_TOKEN: ${{ secrets.COVERALLS_TOKEN }}
+        GITHUB_TOKEN: ${{ secrets.COVERALLS_BOT_PUBLIC_REPO_TOKEN }}
+      with:
+        path-to-profile: ./coverage.txt

.gitignore

@@ -6,8 +6,6 @@
 *.so
 *.dylib
 
-cmd/relaynode/relaynode
-cmd/taillogin/taillogin
 cmd/tailscale/tailscale
 cmd/tailscaled/tailscaled
 
@@ -19,3 +17,7 @@ cmd/tailscaled/tailscaled
 
 # Dependency directories (remove the comment below to include it)
 # vendor/
+
+# direnv config, this may be different for other people so it's probably safer
+# to make this nonspecific.
+.envrc

Dockerfile

@@ -2,6 +2,23 @@
 # Use of this source code is governed by a BSD-style
 # license that can be found in the LICENSE file.
 
+############################################################################
+#
+# WARNING: Tailscale is not yet officially supported in Docker,
+# Kubernetes, etc.
+#
+# It might work, but we don't regularly test it, and it's not as polished as
+# our currently supported platforms. This is provided for people who know
+# how Tailscale works and what they're doing.
+#
+# Our tracking bug for officially support container use cases is:
+#    https://github.com/tailscale/tailscale/issues/504
+#
+# Also, see the various bugs tagged "containers":
+#    https://github.com/tailscale/tailscale/labels/containers
+#
+############################################################################
+
 # This Dockerfile includes all the tailscale binaries.
 #
 # To build the Dockerfile:
@@ -21,7 +38,7 @@
 #     $ docker exec tailscaled tailscale status
 
 
-FROM golang:1.14-alpine AS build-env
+FROM golang:1.15-alpine AS build-env
 
 WORKDIR /go/src/tailscale
 

README.md

@@ -63,8 +63,13 @@ Origin](https://en.wikipedia.org/wiki/Developer_Certificate_of_Origin)
 
 ## About Us
 
-We are apenwarr, bradfitz, crawshaw, danderson, dfcarney, josharian
-from Tailscale Inc.
-You can learn more about us from [our website](https://tailscale.com).
+[Tailscale](https://tailscale.com/) is primarily developed by the
+people at https://github.com/orgs/tailscale/people. For other contributors,
+see:
+
+* https://github.com/tailscale/tailscale/graphs/contributors
+* https://github.com/tailscale/tailscale-android/graphs/contributors
+
+## Legal
 
 WireGuard is a registered trademark of Jason A. Donenfeld.

VERSION.txt

@@ -1 +1 @@
-1.2.7
+1.3.0

api.md

@@ -0,0 +1,774 @@
+# Tailscale API
+
+The Tailscale API is a (mostly) RESTful API. Typically, POST bodies should be JSON encoded and responses will be JSON encoded.
+
+# Authentication
+Currently based on {some authentication method}. Visit the [admin panel](https://api.tailscale.com/admin) and navigate to the `Keys` page. Generate an API Key and keep it safe. Provide the key as the user key in basic auth when making calls to Tailscale API endpoints.
+
+# APIs
+
+* **[Devices](#device)**
+  - [GET device](#device-get)
+  - [DELETE device](#device-delete)
+  - Routes
+    - [GET device routes](#device-routes-get)
+    - [POST device routes](#device-routes-post)
+* **[Tailnets](#tailnet)**
+  - ACLs
+    - [GET tailnet ACL](#tailnet-acl-get)
+    - [POST tailnet ACL](#tailnet-acl-post): set ACL for a tailnet
+    - [POST tailnet ACL preview](#tailnet-acl-preview-post): preview rule matches on an ACL for a resource
+  - [Devices](#tailnet-devices)
+    - [GET tailnet devices](#tailnet-devices-get)
+  - [DNS](#tailnet-dns)
+    - [GET tailnet DNS nameservers](#tailnet-dns-nameservers-get)
+    - [POST tailnet DNS nameservers](#tailnet-dns-nameservers-post)
+    - [GET tailnet DNS preferences](#tailnet-dns-preferences-get)
+    - [POST tailnet DNS preferences](#tailnet-dns-preferences-post)
+    - [GET tailnet DNS searchpaths](#tailnet-dns-searchpaths-get)
+    - [POST tailnet DNS searchpaths](#tailnet-dns-searchpaths-post)
+
+## Device
+<!-- TODO: description about what devices are -->
+Each Tailscale-connected device has a globally-unique identifier number which we refer as the "deviceID" or sometimes, just "id". 
+You can use the deviceID to specify operations on a specific device, like retrieving its subnet routes.
+
+To find the deviceID of a particular device, you can use the ["GET /devices"](#getdevices) API call and generate a list of devices on your network. 
+Find the device you're looking for and get the "id" field.
+This is your deviceID. 
+
+<a name=device-get></div>
+
+#### `GET /api/v2/device/:deviceid` - lists the details for a device
+Returns the details for the specified device.
+Supply the device of interest in the path using its ID.
+Use the `fields` query parameter to explicitly indicate which fields are returned.
+
+
+##### Parameters
+##### Query Parameters
+`fields` - Controls which fields will be included in the returned response.
+Currently, supported options are: 
+* `all`: returns all fields in the response.
+* `default`: return all fields except:
+  * `enabledRoutes`
+  * `advertisedRoutes`
+  * `clientConnectivity` (which contains the following fields: `mappingVariesByDestIP`, `derp`, `endpoints`, `latency`, and `clientSupports`)
+
+Use commas to separate multiple options.
+If more than one option is indicated, then the union is used.
+For example, for `fields=default,all`, all fields are returned.
+If the `fields` parameter is not provided, then the default option is used.
+
+##### Example 
+```
+GET /api/v2/device/12345
+curl 'https://api.tailscale.com/api/v2/device/12345?fields=all' \
+  -u "tskey-yourapikey123:"
+```
+
+Response
+```
+{
+  "addresses":[
+    "100.105.58.116"
+  ],
+  "id":"12345",
+  "user":"user1@example.com",
+  "name":"user1-device.example.com",
+  "hostname":"User1-Device",
+  "clientVersion":"date.20201107",
+  "updateAvailable":false,
+  "os":"macOS",
+  "created":"2020-11-20T20:56:49Z",
+  "lastSeen":"2020-11-20T16:15:55-05:00",
+  "keyExpiryDisabled":false,
+  "expires":"2021-05-19T20:56:49Z",
+  "authorized":true,
+  "isExternal":false,
+  "machineKey":"mkey:user1-machine-key",
+  "nodeKey":"nodekey:user1-node-key",
+  "blocksIncomingConnections":false,
+  "enabledRoutes":[
+    
+  ],
+  "advertisedRoutes":[
+    
+  ],
+  "clientConnectivity": {
+    "endpoints":[
+      "209.195.87.231:59128",
+      "192.168.0.173:59128"
+    ],
+    "derp":"",
+    "mappingVariesByDestIP":false,
+    "latency":{
+      "Dallas":{
+        "latencyMs":60.463043
+      },
+      "New York City":{
+        "preferred":true,
+        "latencyMs":31.323811
+      },
+      "San Francisco":{
+        "latencyMs":81.313389
+      }
+    },
+    "clientSupports":{
+      "hairPinning":false,
+      "ipv6":false,
+      "pcp":false,
+      "pmp":false,
+      "udp":true,
+      "upnp":false
+    }
+  }
+}
+```
+
+<a name=device-delete></div>
+
+#### `DELETE /api/v2/device/:deviceID` - deletes the device from its tailnet
+Deletes the provided device from its tailnet. 
+The device must belong to the user's tailnet.
+Deleting shared/external devices is not supported.
+Supply the device of interest in the path using its ID.
+
+
+##### Parameters
+No parameters.
+
+##### Example
+```
+DELETE /api/v2/device/12345
+curl -X DELETE 'https://api.tailscale.com/api/v2/device/12345' \
+  -u "tskey-yourapikey123:" -v
+```
+
+Response
+
+If successful, the response should be empty: 
+```
+< HTTP/1.1 200 OK
+...
+* Connection #0 to host left intact
+* Closing connection 0
+```
+
+If the device is not owned by your tailnet: 
+```
+< HTTP/1.1 501 Not Implemented
+...
+{"message":"cannot delete devices outside of your tailnet"}
+```
+
+
+<a name=device-routes-get></div>
+
+#### `GET /api/v2/device/:deviceID/routes` - fetch subnet routes that are advertised and enabled for a device
+
+Retrieves the list of subnet routes that a device is advertising, as well as those that are enabled for it. Enabled routes are not necessarily advertised (e.g. for pre-enabling), and likewise, advertised routes are not necessarily enabled.
+
+##### Parameters
+
+No parameters.
+
+##### Example
+
+```
+curl 'https://api.tailscale.com/api/v2/device/11055/routes' \
+-u "tskey-yourapikey123:"
+```
+
+Response
+```
+{
+   "advertisedRoutes" : [
+      "10.0.1.0/24",
+      "1.2.0.0/16",
+      "2.0.0.0/24"
+   ],
+   "enabledRoutes" : []
+}
+```
+
+<a name=device-routes-post></div>
+
+#### `POST /api/v2/device/:deviceID/routes` - set the subnet routes that are enabled for a device
+
+Sets which subnet routes are enabled to be routed by a device by replacing the existing list of subnet routes with the supplied parameters. Routes can be enabled without a device advertising them (e.g. for preauth). Returns a list of enabled subnet routes and a list of advertised subnet routes for a device.
+
+##### Parameters
+
+###### POST Body
+`routes` - The new list of enabled subnet routes in JSON.
+```
+{
+  "routes": ["10.0.1.0/24", "1.2.0.0/16", "2.0.0.0/24"]
+}
+```
+
+##### Example
+
+```
+curl 'https://api.tailscale.com/api/v2/device/11055/routes' \
+-u "tskey-yourapikey123:" \
+--data-binary '{"routes": ["10.0.1.0/24", "1.2.0.0/16", "2.0.0.0/24"]}'
+```
+
+Response
+
+```
+{
+   "advertisedRoutes" : [
+      "10.0.1.0/24",
+      "1.2.0.0/16",
+      "2.0.0.0/24"
+   ],
+   "enabledRoutes" : [
+      "10.0.1.0/24",
+      "1.2.0.0/16",
+      "2.0.0.0/24"
+   ]
+}
+```
+
+## Tailnet 
+A tailnet is the name of your Tailscale network. 
+You can find it in the top left corner of the [Admin Panel](https://login.tailscale.com/admin) beside the Tailscale logo.
+
+
+`alice@example.com` belongs to the `example.com` tailnet and would use the following format for API calls:
+
+```
+GET /api/v2/tailnet/example.com/...
+curl https://api.tailscale.com/api/v2/tailnet/example.com/...
+```
+
+
+For solo plans, the tailnet is the email you signed up with.
+So `alice@gmail.com` has the tailnet `alice@gmail.com` since `@gmail.com` is a shared email host.
+Her API calls would have the following format:
+```
+GET /api/v2/tailnet/alice@gmail.com/...
+curl https://api.tailscale.com/api/v2/tailnet/alice@gmail.com/...
+```
+
+Tailnets are a top-level resource. ACL is an example of a resource that is tied to a top-level tailnet.
+
+For more information on Tailscale networks/tailnets, click [here](https://tailscale.com/kb/1064/invite-team-members).
+
+### ACL
+
+<a name=tailnet-acl-get></a>
+
+#### `GET /api/v2/tailnet/:tailnet/acl` - fetch ACL for a tailnet
+
+Retrieves the ACL that is currently set for the given tailnet. Supply the tailnet of interest in the path. This endpoint can send back either the HuJSON of the ACL or a parsed JSON, depending on the `Accept` header.
+
+##### Parameters
+
+###### Headers
+`Accept` - Response is parsed `JSON` if `application/json` is explicitly named, otherwise HuJSON will be returned.
+
+##### Returns
+Returns the ACL HuJSON by default. Returns a parsed JSON of the ACL (sans comments) if the `Accept` type is explicitly set to `application/json`. An `ETag` header is also sent in the response, which can be optionally used in POST requests to avoid missed updates.
+<!-- TODO (chungdaniel): define error types and a set of docs for them -->
+
+##### Example
+
+###### Requesting a HuJSON response:
+```
+GET /api/v2/tailnet/example.com/acl
+curl 'https://api.tailscale.com/api/v2/tailnet/example.com/acl' \
+  -u "tskey-yourapikey123:" \
+  -H "Accept: application/hujson" \
+  -v
+```
+
+Response
+```
+...
+Content-Type: application/hujson
+Etag: "e0b2816b418b3f266309d94426ac7668ab3c1fa87798785bf82f1085cc2f6d9c"
+...
+
+// Example/default ACLs for unrestricted connections.
+{
+    "Tests": [],
+    // Declare static groups of users beyond those in the identity service.
+    "Groups": {
+        "group:example": [
+            "user1@example.com",
+            "user2@example.com"
+        ],
+    },
+    // Declare convenient hostname aliases to use in place of IP addresses.
+    "Hosts": {
+        "example-host-1": "100.100.100.100",
+    },
+    // Access control lists.
+    "ACLs": [
+        // Match absolutely everything. Comment out this section if you want
+        // to define specific ACL restrictions.
+        {
+            "Action": "accept",
+            "Users": [
+                "*"
+            ],
+            "Ports": [
+                "*:*"
+            ]
+        },
+    ]
+}
+```
+
+###### Requesting a JSON response:
+```
+GET /api/v2/tailnet/example.com/acl
+curl 'https://api.tailscale.com/api/v2/tailnet/example.com/acl' \
+  -u "tskey-yourapikey123:" \
+  -H "Accept: application/json" \
+  -v
+```
+
+Response
+```
+...
+Content-Type: application/json
+Etag: "e0b2816b418b3f266309d94426ac7668ab3c1fa87798785bf82f1085cc2f6d9c"
+...
+{
+   "acls" : [
+      {
+         "action" : "accept",
+         "ports" : [
+            "*:*"
+         ],
+         "users" : [
+            "*"
+         ]
+      }
+   ],
+   "groups" : {
+      "group:example" : [
+         "user1@example.com",
+         "user2@example.com"
+      ]
+   },
+   "hosts" : {
+      "example-host-1" : "100.100.100.100"
+   }
+}
+```
+
+<a name=tailnet-acl-post></a>
+
+#### `POST /api/v2/tailnet/:tailnet/acl` - set ACL for a tailnet
+
+Sets the ACL for the given tailnet. HuJSON and JSON are both accepted inputs. An `If-Match` header can be set to avoid missed updates.
+
+Returns error for invalid ACLs.
+Returns error if using an `If-Match` header and the ETag does not match.
+
+##### Parameters
+
+###### Headers
+`If-Match` - A request header. Set this value to the ETag header provided in an `ACL GET` request to avoid missed updates.
+
+`Accept` - Sets the return type of the updated ACL. Response is parsed `JSON` if `application/json` is explicitly named, otherwise HuJSON will be returned.
+
+###### POST Body
+ACL JSON or HuJSON (see https://tailscale.com/kb/1018/acls)
+
+##### Example
+```
+POST /api/v2/tailnet/example.com/acl
+curl 'https://api.tailscale.com/api/v2/tailnet/example.com/acl' \
+  -u "tskey-yourapikey123:" \
+  -H "If-Match: \"e0b2816b418b3f266309d94426ac7668ab3c1fa87798785bf82f1085cc2f6d9c\""
+  --data-binary '// Example/default ACLs for unrestricted connections.
+{
+  // Declare tests to check functionality of ACL rules. User must be a valid user with registered machines.
+  "Tests": [
+    // {"User": "user1@example.com", "Allow": ["example-host-1:22"], "Deny": ["example-host-2:100"]},
+  ],
+  // Declare static groups of users beyond those in the identity service.
+  "Groups": {
+    "group:example": [ "user1@example.com", "user2@example.com" ],
+  },
+  // Declare convenient hostname aliases to use in place of IP addresses.
+  "Hosts": {
+    "example-host-1": "100.100.100.100",
+  },
+  // Access control lists.
+  "ACLs": [
+    // Match absolutely everything. Comment out this section if you want
+    // to define specific ACL restrictions.
+    { "Action": "accept", "Users": ["*"], "Ports": ["*:*"] },
+  ]
+}'
+```
+
+Response
+```
+// Example/default ACLs for unrestricted connections.
+{
+  // Declare tests to check functionality of ACL rules. User must be a valid user with registered machines.
+  "Tests": [
+    // {"User": "user1@example.com", "Allow": ["example-host-1:22"], "Deny": ["example-host-2:100"]},
+  ],
+  // Declare static groups of users beyond those in the identity service.
+  "Groups": {
+    "group:example": [ "user1@example.com", "user2@example.com" ],
+  },
+  // Declare convenient hostname aliases to use in place of IP addresses.
+  "Hosts": {
+    "example-host-1": "100.100.100.100",
+  },
+  // Access control lists.
+  "ACLs": [
+    // Match absolutely everything. Comment out this section if you want
+    // to define specific ACL restrictions.
+    { "Action": "accept", "Users": ["*"], "Ports": ["*:*"] },
+  ]
+}
+```
+
+<a name=tailnet-acl-preview-post></a>
+
+#### `POST /api/v2/tailnet/:tailnet/acl/preview` - preview rule matches on an ACL for a resource
+Determines what rules match for a user on an ACL without saving the ACL to the server.
+
+##### Parameters
+
+###### Query Parameters
+`user` - A user's email. The provided ACL is queried with this user to determine which rules match.
+
+###### POST Body
+ACL JSON or HuJSON (see https://tailscale.com/kb/1018/acls)
+
+##### Example
+```
+POST /api/v2/tailnet/example.com/acl/preiew
+curl 'https://api.tailscale.com/api/v2/tailnet/example.com/acl?user=user1@example.com' \
+  -u "tskey-yourapikey123:" \
+  --data-binary '// Example/default ACLs for unrestricted connections.
+{
+  // Declare tests to check functionality of ACL rules. User must be a valid user with registered machines.
+  "Tests": [
+    // {"User": "user1@example.com", "Allow": ["example-host-1:22"], "Deny": ["example-host-2:100"]},
+  ],
+  // Declare static groups of users beyond those in the identity service.
+  "Groups": {
+    "group:example": [ "user1@example.com", "user2@example.com" ],
+  },
+  // Declare convenient hostname aliases to use in place of IP addresses.
+  "Hosts": {
+    "example-host-1": "100.100.100.100",
+  },
+  // Access control lists.
+  "ACLs": [
+    // Match absolutely everything. Comment out this section if you want
+    // to define specific ACL restrictions.
+    { "Action": "accept", "Users": ["*"], "Ports": ["*:*"] },
+  ]
+}'
+```
+
+Response
+```
+{"matches":[{"users":["*"],"ports":["*:*"],"lineNumber":19}],"user":"user1@example.com"}
+```
+
+<a name=tailnet-devices></a>
+
+### Devices
+
+<a name=tailnet-devices-get></a>
+
+#### <a name="getdevices"></a> `GET /api/v2/tailnet/:tailnet/devices` - list the devices for a tailnet
+Lists the devices in a tailnet. 
+Supply the tailnet of interest in the path.
+Use the `fields` query parameter to explicitly indicate which fields are returned.
+
+
+##### Parameters
+
+###### Query Parameters
+`fields` - Controls which fields will be included in the returned response.
+Currently, supported options are: 
+* `all`: Returns all fields in the response.
+* `default`: return all fields except:
+  * `enabledRoutes`
+  * `advertisedRoutes`
+  * `clientConnectivity` (which contains the following fields: `mappingVariesByDestIP`, `derp`, `endpoints`, `latency`, and `clientSupports`)
+
+Use commas to separate multiple options.
+If more than one option is indicated, then the union is used.
+For example, for `fields=default,all`, all fields are returned.
+If the `fields` parameter is not provided, then the default option is used.
+
+##### Example
+
+```
+GET /api/v2/tailnet/example.com/devices
+curl 'https://api.tailscale.com/api/v2/tailnet/example.com/devices' \
+  -u "tskey-yourapikey123:"
+```
+
+Response 
+```
+{
+  "devices":[
+    {
+      "addresses":[
+        "100.68.203.125"
+      ],
+      "clientVersion":"date.20201107",
+      "os":"macOS",
+      "name":"user1-device.example.com",
+      "created":"2020-11-30T22:20:04Z",
+      "lastSeen":"2020-11-30T17:20:04-05:00",
+      "hostname":"User1-Device",
+      "machineKey":"mkey:user1-node-key",
+      "nodeKey":"nodekey:user1-node-key",
+      "id":"12345",
+      "user":"user1@example.com",
+      "expires":"2021-05-29T22:20:04Z",
+      "keyExpiryDisabled":false,
+      "authorized":false,
+      "isExternal":false,
+      "updateAvailable":false,
+      "blocksIncomingConnections":false,
+    },
+    {
+      "addresses":[
+        "100.111.63.90"
+      ],
+      "clientVersion":"date.20201107",
+      "os":"macOS",
+      "name":"user2-device.example.com",
+      "created":"2020-11-30T22:21:03Z",
+      "lastSeen":"2020-11-30T17:21:03-05:00",
+      "hostname":"User2-Device",
+      "machineKey":"mkey:user2-machine-key",
+      "nodeKey":"nodekey:user2-node-key",
+      "id":"48810",
+      "user":"user2@example.com",
+      "expires":"2021-05-29T22:21:03Z",
+      "keyExpiryDisabled":false,
+      "authorized":false,
+      "isExternal":false,
+      "updateAvailable":false,
+      "blocksIncomingConnections":false,
+    }
+  ]
+}
+```
+
+<a name=tailnet-dns></a>
+
+### DNS
+
+<a name=tailnet-dns-nameservers-get></a>
+
+#### `GET /api/v2/tailnet/:tailnet/dns/nameservers` - list the DNS nameservers for a tailnet
+Lists the DNS nameservers for a tailnet. 
+Supply the tailnet of interest in the path.
+
+##### Parameters
+No parameters.
+
+##### Example 
+
+```
+GET /api/v2/tailnet/example.com/dns/nameservers
+curl 'https://api.tailscale.com/api/v2/tailnet/example.com/dns/nameservers' \
+  -u "tskey-yourapikey123:"
+```
+
+Response 
+```
+{
+  "dns": ["8.8.8.8"],
+}
+```
+
+<a name=tailnet-dns-nameservers-post></a>
+
+#### `POST /api/v2/tailnet/:tailnet/dns/nameservers` - replaces the list of DNS nameservers for a tailnet
+Replaces the list of DNS nameservers for the given tailnet with the list supplied by the user. 
+Supply the tailnet of interest in the path.
+Note that changing the list of DNS nameservers may also affect the status of MagicDNS (if MagicDNS is on).
+
+##### Parameters
+###### POST Body
+`dns` - The new list of DNS nameservers in JSON.
+```
+{
+  "dns":["8.8.8.8"]
+}
+```
+
+##### Returns
+Returns the new list of nameservers and the status of MagicDNS. 
+
+If all nameservers have been removed, MagicDNS will be automatically disabled (until explicitly turned back on by the user).
+
+##### Example
+###### Adding DNS nameservers with the MagicDNS on:
+```
+POST /api/v2/tailnet/example.com/dns/nameservers
+curl -X POST 'https://api.tailscale.com/api/v2/tailnet/example.com/dns/nameservers' \
+  -u "tskey-yourapikey123:" \
+  --data-binary '{"dns": ["8.8.8.8"]}'
+```
+
+Response:
+```
+{
+  "dns":["8.8.8.8"],
+  "magicDNS":true,
+}
+```
+
+###### Removing all DNS nameservers with the MagicDNS on:
+```
+POST /api/v2/tailnet/example.com/dns/nameservers
+curl -X POST 'https://api.tailscale.com/api/v2/tailnet/example.com/dns/nameservers' \
+  -u "tskey-yourapikey123:" \
+  --data-binary '{"dns": []}'
+```
+
+Response:
+```
+{
+  "dns":[],
+  "magicDNS": false,
+}
+```
+
+<a name=tailnet-dns-preferences-get></a>
+
+#### `GET /api/v2/tailnet/:tailnet/dns/preferences` - retrieves the DNS preferences for a tailnet
+Retrieves the DNS preferences that are currently set for the given tailnet.
+Supply the tailnet of interest in the path.
+
+##### Parameters
+No parameters. 
+
+##### Example
+```
+GET /api/v2/tailnet/example.com/dns/preferences
+curl 'https://api.tailscale.com/api/v2/tailnet/example.com/dns/preferences' \
+  -u "tskey-yourapikey123:" 
+```
+
+Response:
+```
+{
+  "magicDNS":false, 
+}
+```
+
+<a name=tailnet-dns-preferences-post></a>
+
+#### `POST /api/v2/tailnet/:tailnet/dns/preferences` - replaces the DNS preferences for a tailnet 
+Replaces the DNS preferences for a tailnet, specifically, the MagicDNS setting.
+Note that MagicDNS is dependent on DNS servers. 
+
+If there is at least one DNS server, then MagicDNS can be enabled. 
+Otherwise, it returns an error.
+Note that removing all nameservers will turn off MagicDNS. 
+To reenable it, nameservers must be added back, and MagicDNS must be explicitly turned on.
+
+##### Parameters
+###### POST Body
+The DNS preferences in JSON. Currently, MagicDNS is the only setting available.
+`magicDNS` -  Automatically registers DNS names for devices in your tailnet.
+```
+{
+  "magicDNS": true
+}
+```
+
+##### Example
+```
+POST /api/v2/tailnet/example.com/dns/preferences
+curl -X POST 'https://api.tailscale.com/api/v2/tailnet/example.com/dns/preferences' \
+  -u "tskey-yourapikey123:" \
+  --data-binary '{"magicDNS": true}'
+```
+
+
+Response:
+
+If there are no DNS servers, it returns an error message:
+```
+{
+  "message":"need at least one nameserver to enable MagicDNS"
+}
+```
+
+If there are DNS servers: 
+```
+{
+  "magicDNS":true,
+}
+```
+
+<a name=tailnet-dns-searchpaths-get></a>
+
+#### `GET /api/v2/tailnet/:tailnet/dns/searchpaths` - retrieves the search paths for a tailnet 
+Retrieves the list of search paths that is currently set for the given tailnet. 
+Supply the tailnet of interest in the path.
+
+
+##### Parameters
+No parameters.
+
+##### Example
+```
+GET /api/v2/tailnet/example.com/dns/searchpaths
+curl 'https://api.tailscale.com/api/v2/tailnet/example.com/dns/searchpaths' \
+  -u "tskey-yourapikey123:" 
+```
+
+Response:
+```
+{
+  "searchPaths": ["user1.example.com"],
+}
+```
+
+<a name=tailnet-dns-searchpaths-post></a>
+
+#### `POST /api/v2/tailnet/:tailnet/dns/searchpaths` - replaces the search paths for a tailnet 
+Replaces the list of searchpaths with the list supplied by the user and returns an error otherwise.
+
+##### Parameters
+
+###### POST Body
+`searchPaths` - A list of searchpaths in JSON.
+```
+{
+  "searchPaths: ["user1.example.com", "user2.example.com"]
+}
+```
+
+##### Example
+```
+POST /api/v2/tailnet/example.com/dns/searchpaths
+curl -X POST 'https://api.tailscale.com/api/v2/tailnet/example.com/dns/searchpaths' \
+  -u "tskey-yourapikey123:" \
+  --data-binary '{"searchPaths": ["user1.example.com", "user2.example.com"]}'
+```
+
+Response:
+```
+{
+  "searchPaths": ["user1.example.com", "user2.example.com"],
+}
+```

cmd/cloner/cloner.go

@@ -140,7 +140,7 @@ func main() {
 		flag.Usage()
 		os.Exit(2)
 	}
-	if err := ioutil.WriteFile(output, out, 0666); err != nil {
+	if err := ioutil.WriteFile(output, out, 0644); err != nil {
 		log.Fatal(err)
 	}
 }

cmd/derper/derper.go

@@ -25,7 +25,6 @@ import (
 	"strings"
 	"time"
 
-	"github.com/tailscale/wireguard-go/wgcfg"
 	"golang.org/x/crypto/acme/autocert"
 	"tailscale.com/atomicfile"
 	"tailscale.com/derp"
@@ -35,6 +34,7 @@ import (
 	"tailscale.com/net/stun"
 	"tailscale.com/tsweb"
 	"tailscale.com/types/key"
+	"tailscale.com/types/wgkey"
 	"tailscale.com/version"
 )
 
@@ -51,7 +51,7 @@ var (
 )
 
 type config struct {
-	PrivateKey wgcfg.PrivateKey
+	PrivateKey wgkey.Private
 }
 
 func loadConfig() config {
@@ -77,8 +77,8 @@ func loadConfig() config {
 	}
 }
 
-func mustNewKey() wgcfg.PrivateKey {
-	key, err := wgcfg.NewPrivateKey()
+func mustNewKey() wgkey.Private {
+	key, err := wgkey.NewPrivate()
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -97,7 +97,7 @@ func writeNewConfig() config {
 	if err != nil {
 		log.Fatal(err)
 	}
-	if err := atomicfile.WriteFile(*configPath, b, 0666); err != nil {
+	if err := atomicfile.WriteFile(*configPath, b, 0600); err != nil {
 		log.Fatal(err)
 	}
 	return cfg

cmd/tailscale/cli/cli.go

@@ -99,7 +99,7 @@ func connect(ctx context.Context) (net.Conn, *ipn.BackendClient, context.Context
 		if runtime.GOOS != "windows" && rootArgs.socket == "" {
 			fatalf("--socket cannot be empty")
 		}
-		fatalf("Failed to connect to connect to tailscaled. (safesocket.Connect: %v)\n", err)
+		fatalf("Failed to connect to tailscaled. (safesocket.Connect: %v)\n", err)
 	}
 	clientToServer := func(b []byte) {
 		ipn.WriteMsg(c, b)

cmd/tailscale/cli/netcheck.go

@@ -17,7 +17,6 @@ import (
 
 	"github.com/peterbourgon/ff/v2/ffcli"
 	"tailscale.com/derp/derpmap"
-	"tailscale.com/net/dnscache"
 	"tailscale.com/net/netcheck"
 	"tailscale.com/tailcfg"
 	"tailscale.com/types/logger"
@@ -44,9 +43,7 @@ var netcheckArgs struct {
 }
 
 func runNetcheck(ctx context.Context, args []string) error {
-	c := &netcheck.Client{
-		DNSCache: dnscache.Get(),
-	}
+	c := &netcheck.Client{}
 	if netcheckArgs.verbose {
 		c.Logf = logger.WithPrefix(log.Printf, "netcheck: ")
 		c.Verbose = true

cmd/tailscale/cli/status.go

@@ -14,6 +14,8 @@ import (
 	"net"
 	"net/http"
 	"os"
+	"sort"
+	"strings"
 	"time"
 
 	"github.com/peterbourgon/ff/v2/ffcli"
@@ -21,6 +23,7 @@ import (
 	"tailscale.com/ipn"
 	"tailscale.com/ipn/ipnstate"
 	"tailscale.com/net/interfaces"
+	"tailscale.com/util/dnsname"
 )
 
 var statusCmd = &ffcli.Command{
@@ -34,6 +37,7 @@ var statusCmd = &ffcli.Command{
 		fs.BoolVar(&statusArgs.web, "web", false, "run webserver with HTML showing status")
 		fs.BoolVar(&statusArgs.active, "active", false, "filter output to only peers with active sessions (not applicable to web mode)")
 		fs.BoolVar(&statusArgs.self, "self", true, "show status of local machine")
+		fs.BoolVar(&statusArgs.peers, "peers", true, "show status of peers")
 		fs.StringVar(&statusArgs.listen, "listen", "127.0.0.1:8384", "listen address; use port 0 for automatic")
 		fs.BoolVar(&statusArgs.browser, "browser", true, "Open a browser in web mode")
 		return fs
@@ -47,6 +51,7 @@ var statusArgs struct {
 	browser bool   // in web mode, whether to open browser
 	active  bool   // in CLI mode, filter output to only peers with active sessions
 	self    bool   // in CLI mode, show status of local machine
+	peers   bool   // in CLI mode, show status of peer machines
 }
 
 func runStatus(ctx context.Context, args []string) error {
@@ -136,30 +141,30 @@ func runStatus(ctx context.Context, args []string) error {
 	f := func(format string, a ...interface{}) { fmt.Fprintf(&buf, format, a...) }
 	printPS := func(ps *ipnstate.PeerStatus) {
 		active := peerActive(ps)
-		f("%s %-7s %-15s %-18s tx=%8d rx=%8d ",
-			ps.PublicKey.ShortString(),
-			ps.OS,
+		f("%-15s %-20s %-12s %-7s ",
 			ps.TailAddr,
-			ps.SimpleHostName(),
-			ps.TxBytes,
-			ps.RxBytes,
+			dnsOrQuoteHostname(st, ps),
+			ownerLogin(st, ps),
+			ps.OS,
 		)
 		relay := ps.Relay
-		if active && relay != "" && ps.CurAddr == "" {
-			relay = "*" + relay + "*"
-		} else {
-			relay = " " + relay
-		}
-		f("%-6s", relay)
-		for i, addr := range ps.Addrs {
-			if i != 0 {
-				f(", ")
-			}
-			if addr == ps.CurAddr {
-				f("*%s*", addr)
+		anyTraffic := ps.TxBytes != 0 || ps.RxBytes != 0
+		if !active {
+			if anyTraffic {
+				f("idle")
 			} else {
-				f("%s", addr)
+				f("-")
 			}
+		} else {
+			f("active; ")
+			if relay != "" && ps.CurAddr == "" {
+				f("relay %q", relay)
+			} else if ps.CurAddr != "" {
+				f("direct %s", ps.CurAddr)
+			}
+		}
+		if anyTraffic {
+			f(", tx %d rx %d", ps.TxBytes, ps.RxBytes)
 		}
 		f("\n")
 	}
@@ -167,13 +172,23 @@ func runStatus(ctx context.Context, args []string) error {
 	if statusArgs.self && st.Self != nil {
 		printPS(st.Self)
 	}
-	for _, peer := range st.Peers() {
-		ps := st.Peer[peer]
-		active := peerActive(ps)
-		if statusArgs.active && !active {
-			continue
+	if statusArgs.peers {
+		var peers []*ipnstate.PeerStatus
+		for _, peer := range st.Peers() {
+			ps := st.Peer[peer]
+			if ps.ShareeNode {
+				continue
+			}
+			peers = append(peers, ps)
+		}
+		sort.Slice(peers, func(i, j int) bool { return sortKey(peers[i]) < sortKey(peers[j]) })
+		for _, ps := range peers {
+			active := peerActive(ps)
+			if statusArgs.active && !active {
+				continue
+			}
+			printPS(ps)
 		}
-		printPS(ps)
 	}
 	os.Stdout.Write(buf.Bytes())
 	return nil
@@ -185,3 +200,37 @@ func runStatus(ctx context.Context, args []string) error {
 func peerActive(ps *ipnstate.PeerStatus) bool {
 	return !ps.LastWrite.IsZero() && time.Since(ps.LastWrite) < 2*time.Minute
 }
+
+func dnsOrQuoteHostname(st *ipnstate.Status, ps *ipnstate.PeerStatus) string {
+	if i := strings.Index(ps.DNSName, "."); i != -1 && dnsname.HasSuffix(ps.DNSName, st.MagicDNSSuffix) {
+		return ps.DNSName[:i]
+	}
+	if ps.DNSName != "" {
+		return strings.TrimRight(ps.DNSName, ".")
+	}
+	return fmt.Sprintf("(%q)", strings.ReplaceAll(ps.SimpleHostName(), " ", "_"))
+}
+
+func sortKey(ps *ipnstate.PeerStatus) string {
+	if ps.DNSName != "" {
+		return ps.DNSName
+	}
+	if ps.HostName != "" {
+		return ps.HostName
+	}
+	return ps.TailAddr
+}
+
+func ownerLogin(st *ipnstate.Status, ps *ipnstate.PeerStatus) string {
+	if ps.UserID.IsZero() {
+		return "-"
+	}
+	u, ok := st.User[ps.UserID]
+	if !ok {
+		return fmt.Sprint(ps.UserID)
+	}
+	if i := strings.Index(u.LoginName, "@"); i != -1 {
+		return u.LoginName[:i+1]
+	}
+	return u.LoginName
+}

cmd/tailscale/cli/up.go

@@ -19,7 +19,6 @@ import (
 	"sync"
 
 	"github.com/peterbourgon/ff/v2/ffcli"
-	"github.com/tailscale/wireguard-go/wgcfg"
 	"inet.af/netaddr"
 	"tailscale.com/ipn"
 	"tailscale.com/tailcfg"
@@ -85,29 +84,6 @@ var upArgs struct {
 	hostname        string
 }
 
-// parseIPOrCIDR parses an IP address or a CIDR prefix. If the input
-// is an IP address, it is returned in CIDR form with a /32 mask for
-// IPv4 or a /128 mask for IPv6.
-func parseIPOrCIDR(s string) (wgcfg.CIDR, bool) {
-	if strings.Contains(s, "/") {
-		ret, err := wgcfg.ParseCIDR(s)
-		if err != nil {
-			return wgcfg.CIDR{}, false
-		}
-		return ret, true
-	}
-
-	ip, ok := wgcfg.ParseIP(s)
-	if !ok {
-		return wgcfg.CIDR{}, false
-	}
-	if ip.Is4() {
-		return wgcfg.CIDR{IP: ip, Mask: 32}, true
-	} else {
-		return wgcfg.CIDR{IP: ip, Mask: 128}, true
-	}
-}
-
 func isBSD(s string) bool {
 	return s == "dragonfly" || s == "freebsd" || s == "netbsd" || s == "openbsd"
 }
@@ -162,19 +138,18 @@ func runUp(ctx context.Context, args []string) error {
 		}
 	}
 
-	var routes []wgcfg.CIDR
+	var routes []netaddr.IPPrefix
 	if upArgs.advertiseRoutes != "" {
 		advroutes := strings.Split(upArgs.advertiseRoutes, ",")
 		for _, s := range advroutes {
-			cidr, ok := parseIPOrCIDR(s)
-			ipp, err := netaddr.ParseIPPrefix(s) // parse it with other pawith both packages
-			if !ok || err != nil {
+			ipp, err := netaddr.ParseIPPrefix(s)
+			if err != nil {
 				fatalf("%q is not a valid IP address or CIDR prefix", s)
 			}
 			if ipp != ipp.Masked() {
 				fatalf("%s has non-address bits set; expected %s", ipp, ipp.Masked())
 			}
-			routes = append(routes, cidr)
+			routes = append(routes, ipp)
 		}
 		checkIPForwarding()
 	}

cmd/tailscale/depaware.txt

@@ -9,11 +9,11 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
    W 💣 github.com/go-ole/go-ole                                     from github.com/go-ole/go-ole/oleutil+
    W 💣 github.com/go-ole/go-ole/oleutil                             from tailscale.com/wgengine/winnet
    L 💣 github.com/godbus/dbus/v5                                    from tailscale.com/wgengine/router/dns
-        github.com/golang/groupcache/lru                             from tailscale.com/wgengine/filter+
-   L    github.com/jsimonetti/rtnetlink                              from tailscale.com/wgengine/monitor
+   L 💣 github.com/jsimonetti/rtnetlink                              from tailscale.com/wgengine/monitor
    L    github.com/jsimonetti/rtnetlink/internal/unix                from github.com/jsimonetti/rtnetlink
    L 💣 github.com/mdlayher/netlink                                  from github.com/jsimonetti/rtnetlink+
    L 💣 github.com/mdlayher/netlink/nlenc                            from github.com/jsimonetti/rtnetlink+
+   L    github.com/mdlayher/sdnotify                                 from tailscale.com/util/systemd
         github.com/peterbourgon/ff/v2                                from github.com/peterbourgon/ff/v2/ffcli
         github.com/peterbourgon/ff/v2/ffcli                          from tailscale.com/cmd/tailscale/cli
      💣 github.com/tailscale/wireguard-go/conn                       from github.com/tailscale/wireguard-go/device+
@@ -24,18 +24,15 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         github.com/tailscale/wireguard-go/ratelimiter                from github.com/tailscale/wireguard-go/device
         github.com/tailscale/wireguard-go/replay                     from github.com/tailscale/wireguard-go/device
         github.com/tailscale/wireguard-go/rwcancel                   from github.com/tailscale/wireguard-go/device+
-        github.com/tailscale/wireguard-go/tai64n                     from github.com/tailscale/wireguard-go/device
+        github.com/tailscale/wireguard-go/tai64n                     from github.com/tailscale/wireguard-go/device+
      💣 github.com/tailscale/wireguard-go/tun                        from github.com/tailscale/wireguard-go/device+
-   W 💣 github.com/tailscale/wireguard-go/tun/wintun                 from github.com/tailscale/wireguard-go/tun
-   W 💣 github.com/tailscale/wireguard-go/tun/wintun/iphlpapi        from github.com/tailscale/wireguard-go/tun/wintun
-   W 💣 github.com/tailscale/wireguard-go/tun/wintun/namespaceapi    from github.com/tailscale/wireguard-go/tun/wintun
-   W 💣 github.com/tailscale/wireguard-go/tun/wintun/nci             from github.com/tailscale/wireguard-go/tun/wintun
-   W 💣 github.com/tailscale/wireguard-go/tun/wintun/registry        from github.com/tailscale/wireguard-go/tun/wintun
-   W 💣 github.com/tailscale/wireguard-go/tun/wintun/setupapi        from github.com/tailscale/wireguard-go/tun/wintun
-        github.com/tailscale/wireguard-go/wgcfg                      from github.com/tailscale/wireguard-go/conn+
+   W 💣 github.com/tailscale/wireguard-go/tun/wintun                 from github.com/tailscale/wireguard-go/tun+
+        github.com/tailscale/wireguard-go/wgcfg                      from github.com/tailscale/wireguard-go/device+
         github.com/tcnksm/go-httpstat                                from tailscale.com/net/netcheck
         github.com/toqueteos/webbrowser                              from tailscale.com/cmd/tailscale/cli
+     💣 go4.org/intern                                               from inet.af/netaddr
      💣 go4.org/mem                                                  from tailscale.com/control/controlclient+
+        go4.org/unsafe/assume-no-moving-gc                           from go4.org/intern
    W 💣 golang.zx2c4.com/wireguard/windows/tunnel/winipcfg           from tailscale.com/net/interfaces+
         inet.af/netaddr                                              from tailscale.com/cmd/tailscale/cli+
         rsc.io/goversion/version                                     from tailscale.com/version
@@ -53,10 +50,12 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         tailscale.com/log/logheap                                    from tailscale.com/control/controlclient
         tailscale.com/logtail/backoff                                from tailscale.com/control/controlclient+
         tailscale.com/metrics                                        from tailscale.com/derp
-        tailscale.com/net/dnscache                                   from tailscale.com/cmd/tailscale/cli+
+        tailscale.com/net/dnscache                                   from tailscale.com/control/controlclient+
+        tailscale.com/net/flowtrack                                  from tailscale.com/wgengine/filter+
      💣 tailscale.com/net/interfaces                                 from tailscale.com/cmd/tailscale/cli+
         tailscale.com/net/netcheck                                   from tailscale.com/cmd/tailscale/cli+
         tailscale.com/net/netns                                      from tailscale.com/control/controlclient+
+        tailscale.com/net/packet                                     from tailscale.com/wgengine+
         tailscale.com/net/stun                                       from tailscale.com/net/netcheck+
         tailscale.com/net/tlsdial                                    from tailscale.com/control/controlclient+
         tailscale.com/net/tsaddr                                     from tailscale.com/ipn+
@@ -66,26 +65,27 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         tailscale.com/safesocket                                     from tailscale.com/cmd/tailscale/cli
      💣 tailscale.com/syncs                                          from tailscale.com/net/interfaces+
         tailscale.com/tailcfg                                        from tailscale.com/cmd/tailscale/cli+
-  DW    tailscale.com/tempfork/osexec                                from tailscale.com/portlist
    W    tailscale.com/tsconst                                        from tailscale.com/net/interfaces
         tailscale.com/types/empty                                    from tailscale.com/control/controlclient+
         tailscale.com/types/key                                      from tailscale.com/cmd/tailscale/cli+
         tailscale.com/types/logger                                   from tailscale.com/cmd/tailscale/cli+
         tailscale.com/types/nettype                                  from tailscale.com/wgengine/magicsock
         tailscale.com/types/opt                                      from tailscale.com/control/controlclient+
-        tailscale.com/types/strbuilder                               from tailscale.com/wgengine/packet
+        tailscale.com/types/strbuilder                               from tailscale.com/net/packet
         tailscale.com/types/structs                                  from tailscale.com/control/controlclient+
-   W    tailscale.com/util/endian                                    from tailscale.com/net/netns
+        tailscale.com/types/wgkey                                    from tailscale.com/control/controlclient+
+        tailscale.com/util/dnsname                                   from tailscale.com/cmd/tailscale/cli+
+  LW    tailscale.com/util/endian                                    from tailscale.com/net/netns+
         tailscale.com/util/lineread                                  from tailscale.com/control/controlclient+
+        tailscale.com/util/systemd                                   from tailscale.com/control/controlclient+
         tailscale.com/version                                        from tailscale.com/cmd/tailscale/cli+
         tailscale.com/version/distro                                 from tailscale.com/cmd/tailscale/cli+
         tailscale.com/wgengine                                       from tailscale.com/ipn
         tailscale.com/wgengine/filter                                from tailscale.com/control/controlclient+
         tailscale.com/wgengine/magicsock                             from tailscale.com/wgengine
      💣 tailscale.com/wgengine/monitor                               from tailscale.com/cmd/tailscale/cli+
-        tailscale.com/wgengine/packet                                from tailscale.com/wgengine+
         tailscale.com/wgengine/router                                from tailscale.com/cmd/tailscale/cli+
-     💣 tailscale.com/wgengine/router/dns                            from tailscale.com/ipn+
+        tailscale.com/wgengine/router/dns                            from tailscale.com/ipn+
         tailscale.com/wgengine/tsdns                                 from tailscale.com/ipn+
         tailscale.com/wgengine/tstun                                 from tailscale.com/wgengine
    W 💣 tailscale.com/wgengine/winnet                                from tailscale.com/wgengine/router
@@ -119,11 +119,11 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         golang.org/x/sys/cpu                                         from golang.org/x/crypto/blake2b+
   LD    golang.org/x/sys/unix                                        from github.com/jsimonetti/rtnetlink/internal/unix+
    W    golang.org/x/sys/windows                                     from github.com/apenwarr/fixconsole+
-   W    golang.org/x/sys/windows/registry                            from github.com/tailscale/wireguard-go/tun/wintun+
+   W    golang.org/x/sys/windows/registry                            from golang.zx2c4.com/wireguard/windows/tunnel/winipcfg+
         golang.org/x/text/secure/bidirule                            from golang.org/x/net/idna
         golang.org/x/text/transform                                  from golang.org/x/text/secure/bidirule+
         golang.org/x/text/unicode/bidi                               from golang.org/x/net/idna+
-        golang.org/x/text/unicode/norm                               from github.com/tailscale/wireguard-go/tun/wintun+
+        golang.org/x/text/unicode/norm                               from golang.org/x/net/idna
         golang.org/x/time/rate                                       from tailscale.com/types/logger+
         bufio                                                        from compress/flate+
         bytes                                                        from bufio+
@@ -171,6 +171,7 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         hash/adler32                                                 from compress/zlib
         hash/crc32                                                   from compress/gzip+
         hash/fnv                                                     from tailscale.com/wgengine/magicsock
+        hash/maphash                                                 from go4.org/mem
         html                                                         from tailscale.com/ipn/ipnstate
         io                                                           from bufio+
         io/ioutil                                                    from crypto/tls+
@@ -197,6 +198,7 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         reflect                                                      from crypto/x509+
         regexp                                                       from github.com/coreos/go-iptables/iptables+
         regexp/syntax                                                from regexp
+        runtime/debug                                                from golang.org/x/sync/singleflight
         runtime/pprof                                                from tailscale.com/log/logheap+
         sort                                                         from compress/flate+
         strconv                                                      from compress/flate+

cmd/tailscaled/depaware.txt

@@ -9,8 +9,8 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
    W 💣 github.com/go-ole/go-ole                                     from github.com/go-ole/go-ole/oleutil+
    W 💣 github.com/go-ole/go-ole/oleutil                             from tailscale.com/wgengine/winnet
    L 💣 github.com/godbus/dbus/v5                                    from tailscale.com/wgengine/router/dns
-        github.com/golang/groupcache/lru                             from tailscale.com/wgengine/filter+
-   L    github.com/jsimonetti/rtnetlink                              from tailscale.com/wgengine/monitor
+        github.com/google/btree                                      from gvisor.dev/gvisor/pkg/tcpip/header+
+   L 💣 github.com/jsimonetti/rtnetlink                              from tailscale.com/wgengine/monitor
    L    github.com/jsimonetti/rtnetlink/internal/unix                from github.com/jsimonetti/rtnetlink
         github.com/klauspost/compress/fse                            from github.com/klauspost/compress/huff0
         github.com/klauspost/compress/huff0                          from github.com/klauspost/compress/zstd
@@ -19,6 +19,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         github.com/klauspost/compress/zstd/internal/xxhash           from github.com/klauspost/compress/zstd
    L 💣 github.com/mdlayher/netlink                                  from github.com/jsimonetti/rtnetlink+
    L 💣 github.com/mdlayher/netlink/nlenc                            from github.com/jsimonetti/rtnetlink+
+   L    github.com/mdlayher/sdnotify                                 from tailscale.com/util/systemd
      💣 github.com/tailscale/wireguard-go/conn                       from github.com/tailscale/wireguard-go/device+
      💣 github.com/tailscale/wireguard-go/device                     from tailscale.com/wgengine+
         github.com/tailscale/wireguard-go/device/tokenbucket         from github.com/tailscale/wireguard-go/device
@@ -27,18 +28,44 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         github.com/tailscale/wireguard-go/ratelimiter                from github.com/tailscale/wireguard-go/device
         github.com/tailscale/wireguard-go/replay                     from github.com/tailscale/wireguard-go/device
         github.com/tailscale/wireguard-go/rwcancel                   from github.com/tailscale/wireguard-go/device+
-        github.com/tailscale/wireguard-go/tai64n                     from github.com/tailscale/wireguard-go/device
+        github.com/tailscale/wireguard-go/tai64n                     from github.com/tailscale/wireguard-go/device+
      💣 github.com/tailscale/wireguard-go/tun                        from github.com/tailscale/wireguard-go/device+
-   W 💣 github.com/tailscale/wireguard-go/tun/wintun                 from github.com/tailscale/wireguard-go/tun
-   W 💣 github.com/tailscale/wireguard-go/tun/wintun/iphlpapi        from github.com/tailscale/wireguard-go/tun/wintun
-   W 💣 github.com/tailscale/wireguard-go/tun/wintun/namespaceapi    from github.com/tailscale/wireguard-go/tun/wintun
-   W 💣 github.com/tailscale/wireguard-go/tun/wintun/nci             from github.com/tailscale/wireguard-go/tun/wintun
-   W 💣 github.com/tailscale/wireguard-go/tun/wintun/registry        from github.com/tailscale/wireguard-go/tun/wintun
-   W 💣 github.com/tailscale/wireguard-go/tun/wintun/setupapi        from github.com/tailscale/wireguard-go/tun/wintun
-        github.com/tailscale/wireguard-go/wgcfg                      from github.com/tailscale/wireguard-go/conn+
+   W 💣 github.com/tailscale/wireguard-go/tun/wintun                 from github.com/tailscale/wireguard-go/tun+
+        github.com/tailscale/wireguard-go/wgcfg                      from github.com/tailscale/wireguard-go/device+
         github.com/tcnksm/go-httpstat                                from tailscale.com/net/netcheck
+     💣 go4.org/intern                                               from inet.af/netaddr
      💣 go4.org/mem                                                  from tailscale.com/control/controlclient+
+        go4.org/unsafe/assume-no-moving-gc                           from go4.org/intern
    W 💣 golang.zx2c4.com/wireguard/windows/tunnel/winipcfg           from tailscale.com/net/interfaces+
+     💣 gvisor.dev/gvisor/pkg/gohacks                                from gvisor.dev/gvisor/pkg/state/wire
+        gvisor.dev/gvisor/pkg/linewriter                             from gvisor.dev/gvisor/pkg/log
+        gvisor.dev/gvisor/pkg/log                                    from gvisor.dev/gvisor/pkg/tcpip/stack+
+        gvisor.dev/gvisor/pkg/rand                                   from gvisor.dev/gvisor/pkg/tcpip/network/hash+
+     💣 gvisor.dev/gvisor/pkg/sleep                                  from gvisor.dev/gvisor/pkg/tcpip/transport/tcp
+     💣 gvisor.dev/gvisor/pkg/state                                  from gvisor.dev/gvisor/pkg/tcpip+
+        gvisor.dev/gvisor/pkg/state/wire                             from gvisor.dev/gvisor/pkg/state
+     💣 gvisor.dev/gvisor/pkg/sync                                   from gvisor.dev/gvisor/pkg/linewriter+
+     💣 gvisor.dev/gvisor/pkg/tcpip                                  from gvisor.dev/gvisor/pkg/tcpip/adapters/gonet+
+        gvisor.dev/gvisor/pkg/tcpip/adapters/gonet                   from tailscale.com/wgengine/netstack
+        gvisor.dev/gvisor/pkg/tcpip/buffer                           from gvisor.dev/gvisor/pkg/tcpip/adapters/gonet+
+        gvisor.dev/gvisor/pkg/tcpip/hash/jenkins                     from gvisor.dev/gvisor/pkg/tcpip/stack+
+        gvisor.dev/gvisor/pkg/tcpip/header                           from gvisor.dev/gvisor/pkg/tcpip/link/channel+
+        gvisor.dev/gvisor/pkg/tcpip/header/parse                     from gvisor.dev/gvisor/pkg/tcpip/network/ipv4+
+        gvisor.dev/gvisor/pkg/tcpip/link/channel                     from tailscale.com/wgengine/netstack
+        gvisor.dev/gvisor/pkg/tcpip/network/fragmentation            from gvisor.dev/gvisor/pkg/tcpip/network/ipv4
+        gvisor.dev/gvisor/pkg/tcpip/network/hash                     from gvisor.dev/gvisor/pkg/tcpip/network/ipv4
+        gvisor.dev/gvisor/pkg/tcpip/network/ip                       from gvisor.dev/gvisor/pkg/tcpip/network/ipv4
+        gvisor.dev/gvisor/pkg/tcpip/network/ipv4                     from tailscale.com/wgengine/netstack
+        gvisor.dev/gvisor/pkg/tcpip/ports                            from gvisor.dev/gvisor/pkg/tcpip/stack+
+        gvisor.dev/gvisor/pkg/tcpip/seqnum                           from gvisor.dev/gvisor/pkg/tcpip/header+
+        gvisor.dev/gvisor/pkg/tcpip/stack                            from gvisor.dev/gvisor/pkg/tcpip/adapters/gonet+
+        gvisor.dev/gvisor/pkg/tcpip/transport/icmp                   from tailscale.com/wgengine/netstack
+        gvisor.dev/gvisor/pkg/tcpip/transport/packet                 from gvisor.dev/gvisor/pkg/tcpip/transport/raw
+        gvisor.dev/gvisor/pkg/tcpip/transport/raw                    from gvisor.dev/gvisor/pkg/tcpip/transport/icmp+
+     💣 gvisor.dev/gvisor/pkg/tcpip/transport/tcp                    from gvisor.dev/gvisor/pkg/tcpip/adapters/gonet+
+        gvisor.dev/gvisor/pkg/tcpip/transport/tcpconntrack           from gvisor.dev/gvisor/pkg/tcpip/stack
+        gvisor.dev/gvisor/pkg/tcpip/transport/udp                    from gvisor.dev/gvisor/pkg/tcpip/adapters/gonet+
+        gvisor.dev/gvisor/pkg/waiter                                 from gvisor.dev/gvisor/pkg/tcpip+
         inet.af/netaddr                                              from tailscale.com/control/controlclient+
         rsc.io/goversion/version                                     from tailscale.com/version
         tailscale.com/atomicfile                                     from tailscale.com/ipn+
@@ -58,11 +85,13 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/logtail/backoff                                from tailscale.com/control/controlclient+
         tailscale.com/logtail/filch                                  from tailscale.com/logpolicy
         tailscale.com/metrics                                        from tailscale.com/derp
-        tailscale.com/net/dnscache                                   from tailscale.com/derp/derphttp+
+        tailscale.com/net/dnscache                                   from tailscale.com/control/controlclient+
+        tailscale.com/net/flowtrack                                  from tailscale.com/wgengine/filter+
      💣 tailscale.com/net/interfaces                                 from tailscale.com/ipn+
         tailscale.com/net/netcheck                                   from tailscale.com/wgengine/magicsock
         tailscale.com/net/netns                                      from tailscale.com/control/controlclient+
      💣 tailscale.com/net/netstat                                    from tailscale.com/ipn/ipnserver
+        tailscale.com/net/packet                                     from tailscale.com/wgengine+
         tailscale.com/net/stun                                       from tailscale.com/net/netcheck+
         tailscale.com/net/tlsdial                                    from tailscale.com/control/controlclient+
         tailscale.com/net/tsaddr                                     from tailscale.com/ipn+
@@ -73,7 +102,6 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/smallzstd                                      from tailscale.com/ipn/ipnserver+
      💣 tailscale.com/syncs                                          from tailscale.com/net/interfaces+
         tailscale.com/tailcfg                                        from tailscale.com/control/controlclient+
-  DW    tailscale.com/tempfork/osexec                                from tailscale.com/portlist
    W    tailscale.com/tsconst                                        from tailscale.com/net/interfaces
         tailscale.com/types/empty                                    from tailscale.com/control/controlclient+
         tailscale.com/types/flagtype                                 from tailscale.com/cmd/tailscaled
@@ -81,22 +109,26 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/types/logger                                   from tailscale.com/cmd/tailscaled+
         tailscale.com/types/nettype                                  from tailscale.com/wgengine/magicsock
         tailscale.com/types/opt                                      from tailscale.com/control/controlclient+
-        tailscale.com/types/strbuilder                               from tailscale.com/wgengine/packet
+        tailscale.com/types/strbuilder                               from tailscale.com/net/packet
         tailscale.com/types/structs                                  from tailscale.com/control/controlclient+
-   W    tailscale.com/util/endian                                    from tailscale.com/net/netns+
+        tailscale.com/types/wgkey                                    from tailscale.com/control/controlclient+
+        tailscale.com/util/dnsname                                   from tailscale.com/control/controlclient+
+  LW    tailscale.com/util/endian                                    from tailscale.com/net/netns+
         tailscale.com/util/lineread                                  from tailscale.com/control/controlclient+
         tailscale.com/util/pidowner                                  from tailscale.com/ipn/ipnserver
+        tailscale.com/util/racebuild                                 from tailscale.com/logpolicy
+        tailscale.com/util/systemd                                   from tailscale.com/control/controlclient+
         tailscale.com/version                                        from tailscale.com/cmd/tailscaled+
         tailscale.com/version/distro                                 from tailscale.com/control/controlclient+
         tailscale.com/wgengine                                       from tailscale.com/cmd/tailscaled+
         tailscale.com/wgengine/filter                                from tailscale.com/control/controlclient+
         tailscale.com/wgengine/magicsock                             from tailscale.com/cmd/tailscaled+
      💣 tailscale.com/wgengine/monitor                               from tailscale.com/wgengine
-        tailscale.com/wgengine/packet                                from tailscale.com/wgengine+
+        tailscale.com/wgengine/netstack                              from tailscale.com/cmd/tailscaled
         tailscale.com/wgengine/router                                from tailscale.com/cmd/tailscaled+
-     💣 tailscale.com/wgengine/router/dns                            from tailscale.com/ipn+
+        tailscale.com/wgengine/router/dns                            from tailscale.com/ipn+
         tailscale.com/wgengine/tsdns                                 from tailscale.com/ipn+
-        tailscale.com/wgengine/tstun                                 from tailscale.com/wgengine
+        tailscale.com/wgengine/tstun                                 from tailscale.com/wgengine+
    W 💣 tailscale.com/wgengine/winnet                                from tailscale.com/wgengine/router
         golang.org/x/crypto/blake2b                                  from golang.org/x/crypto/nacl/box
         golang.org/x/crypto/blake2s                                  from github.com/tailscale/wireguard-go/device+
@@ -110,7 +142,6 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         golang.org/x/crypto/nacl/secretbox                           from golang.org/x/crypto/nacl/box
         golang.org/x/crypto/poly1305                                 from github.com/tailscale/wireguard-go/device+
         golang.org/x/crypto/salsa20/salsa                            from golang.org/x/crypto/nacl/box+
-        golang.org/x/crypto/ssh/terminal                             from tailscale.com/logpolicy
         golang.org/x/net/bpf                                         from github.com/mdlayher/netlink+
         golang.org/x/net/context/ctxhttp                             from golang.org/x/oauth2/internal
         golang.org/x/net/dns/dnsmessage                              from net+
@@ -129,17 +160,19 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         golang.org/x/sys/cpu                                         from golang.org/x/crypto/blake2b+
   LD    golang.org/x/sys/unix                                        from github.com/jsimonetti/rtnetlink/internal/unix+
    W    golang.org/x/sys/windows                                     from github.com/apenwarr/fixconsole+
-   W    golang.org/x/sys/windows/registry                            from github.com/tailscale/wireguard-go/tun/wintun+
+   W    golang.org/x/sys/windows/registry                            from golang.zx2c4.com/wireguard/windows/tunnel/winipcfg+
+        golang.org/x/term                                            from tailscale.com/logpolicy
         golang.org/x/text/secure/bidirule                            from golang.org/x/net/idna
         golang.org/x/text/transform                                  from golang.org/x/text/secure/bidirule+
         golang.org/x/text/unicode/bidi                               from golang.org/x/net/idna+
-        golang.org/x/text/unicode/norm                               from github.com/tailscale/wireguard-go/tun/wintun+
+        golang.org/x/text/unicode/norm                               from golang.org/x/net/idna
         golang.org/x/time/rate                                       from tailscale.com/types/logger+
         bufio                                                        from compress/flate+
         bytes                                                        from bufio+
         compress/flate                                               from compress/gzip+
         compress/gzip                                                from internal/profile+
         compress/zlib                                                from debug/elf+
+        container/heap                                               from gvisor.dev/gvisor/pkg/tcpip/transport/tcp
         container/list                                               from crypto/tls+
         context                                                      from crypto/tls+
         crypto                                                       from crypto/ecdsa+
@@ -181,6 +214,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         hash/adler32                                                 from compress/zlib
         hash/crc32                                                   from compress/gzip+
         hash/fnv                                                     from tailscale.com/wgengine/magicsock
+        hash/maphash                                                 from go4.org/mem
         html                                                         from html/template+
         html/template                                                from net/http/pprof
         io                                                           from bufio+

cmd/tailscaled/tailscaled.go

@@ -33,6 +33,7 @@ import (
 	"tailscale.com/version"
 	"tailscale.com/wgengine"
 	"tailscale.com/wgengine/magicsock"
+	"tailscale.com/wgengine/netstack"
 	"tailscale.com/wgengine/router"
 )
 
@@ -64,6 +65,7 @@ var args struct {
 	port       uint16
 	statepath  string
 	socketpath string
+	verbose    int
 }
 
 func main() {
@@ -76,6 +78,7 @@ func main() {
 	}
 
 	printVersion := false
+	flag.IntVar(&args.verbose, "verbose", 0, "log verbosity level; 0 is default, 1 or higher are increasingly verbose")
 	flag.BoolVar(&args.cleanup, "cleanup", false, "clean up system state and exit")
 	flag.BoolVar(&args.fake, "fake", false, "use userspace fake tunnel+routing instead of kernel TUN interface")
 	flag.StringVar(&args.debug, "debug", "", "listen address ([ip]:port) of optional debug server")
@@ -118,6 +121,7 @@ func run() error {
 	var err error
 
 	pol := logpolicy.New("tailnode.log.tailscale.io")
+	pol.SetVerbosityLevel(args.verbose)
 	defer func() {
 		// Finish uploading logs after closing everything else.
 		ctx, cancel := context.WithTimeout(context.Background(), time.Second)
@@ -144,7 +148,11 @@ func run() error {
 
 	var e wgengine.Engine
 	if args.fake {
-		e, err = wgengine.NewFakeUserspaceEngine(logf, args.port)
+		var impl wgengine.FakeImplFunc
+		if args.tunname == "userspace-networking" {
+			impl = netstack.Impl
+		}
+		e, err = wgengine.NewFakeUserspaceEngine(logf, 0, impl)
 	} else {
 		e, err = wgengine.NewUserspaceEngine(logf, args.tunname, args.port)
 	}

cmd/tailscaled/tailscaled.service

@@ -18,6 +18,24 @@ StateDirectory=tailscale
 StateDirectoryMode=0750
 CacheDirectory=tailscale
 CacheDirectoryMode=0750
+Type=notify
+
+DeviceAllow=/dev/net/tun
+DeviceAllow=/dev/null
+DeviceAllow=/dev/random
+DeviceAllow=/dev/urandom
+DevicePolicy=strict
+LockPersonality=true
+MemoryDenyWriteExecute=true
+PrivateTmp=true
+ProtectClock=true
+ProtectControlGroups=true
+ProtectHome=true
+ProtectKernelTunables=true
+ProtectSystem=strict
+ReadWritePaths=/etc/
+RestrictSUIDSGID=true
+SystemCallArchitectures=native
 
 [Install]
 WantedBy=multi-user.target

control/controlclient/auto.go

@@ -17,13 +17,13 @@ import (
 	"sync"
 	"time"
 
-	"github.com/tailscale/wireguard-go/wgcfg"
 	"golang.org/x/oauth2"
 	"tailscale.com/logtail/backoff"
 	"tailscale.com/tailcfg"
 	"tailscale.com/types/empty"
 	"tailscale.com/types/logger"
 	"tailscale.com/types/structs"
+	"tailscale.com/types/wgkey"
 )
 
 // State is the high-level state of the client. It is used only in
@@ -117,15 +117,16 @@ type Client struct {
 	mu         sync.Mutex   // mutex guards the following fields
 	statusFunc func(Status) // called to update Client status
 
-	paused         bool // whether we should stop making HTTP requests
-	unpauseWaiters []chan struct{}
-	loggedIn       bool       // true if currently logged in
-	loginGoal      *LoginGoal // non-nil if some login activity is desired
-	synced         bool       // true if our netmap is up-to-date
-	hostinfo       *tailcfg.Hostinfo
-	inPollNetMap   bool // true if currently running a PollNetMap
-	inSendStatus   int  // number of sendStatus calls currently in progress
-	state          State
+	paused          bool // whether we should stop making HTTP requests
+	unpauseWaiters  []chan struct{}
+	loggedIn        bool       // true if currently logged in
+	loginGoal       *LoginGoal // non-nil if some login activity is desired
+	synced          bool       // true if our netmap is up-to-date
+	hostinfo        *tailcfg.Hostinfo
+	inPollNetMap    bool // true if currently running a PollNetMap
+	inLiteMapUpdate bool // true if a lite (non-streaming) map request is outstanding
+	inSendStatus    int  // number of sendStatus calls currently in progress
+	state           State
 
 	authCtx    context.Context // context used for auth requests
 	mapCtx     context.Context // context used for netmap requests
@@ -182,7 +183,8 @@ func (c *Client) SetPaused(paused bool) {
 	}
 	c.paused = paused
 	if paused {
-		// Just cancel the map routine. The auth routine isn't expensive.
+		// Only cancel the map routine. (The auth routine isn't expensive
+		// so it's fine to keep it running.)
 		c.cancelMapLocked()
 	} else {
 		for _, ch := range c.unpauseWaiters {
@@ -200,6 +202,50 @@ func (c *Client) Start() {
 	go c.mapRoutine()
 }
 
+// sendNewMapRequest either sends a new OmitPeers, non-streaming map request
+// (to just send Hostinfo/Netinfo/Endpoints info, while keeping an existing
+// streaming response open), or start a new streaming one if necessary.
+//
+// It should be called whenever there's something new to tell the server.
+func (c *Client) sendNewMapRequest() {
+	c.mu.Lock()
+
+	// If we're not already streaming a netmap, or if we're already stuck
+	// in a lite update, then tear down everything and start a new stream
+	// (which starts by sending a new map request)
+	if !c.inPollNetMap || c.inLiteMapUpdate {
+		c.mu.Unlock()
+		c.cancelMapSafely()
+		return
+	}
+
+	// Otherwise, send a lite update that doesn't keep a
+	// long-running stream response.
+	defer c.mu.Unlock()
+	c.inLiteMapUpdate = true
+	ctx, cancel := context.WithTimeout(c.mapCtx, 10*time.Second)
+	go func() {
+		defer cancel()
+		t0 := time.Now()
+		err := c.direct.SendLiteMapUpdate(ctx)
+		d := time.Since(t0).Round(time.Millisecond)
+		c.mu.Lock()
+		c.inLiteMapUpdate = false
+		c.mu.Unlock()
+		if err == nil {
+			c.logf("[v1] successful lite map update in %v", d)
+			return
+		}
+		if ctx.Err() == nil {
+			c.logf("lite map update after %v: %v", d, err)
+		}
+		// Fall back to restarting the long-polling map
+		// request (the old heavy way) if the lite update
+		// failed for any reason.
+		c.cancelMapSafely()
+	}()
+}
+
 func (c *Client) cancelAuth() {
 	c.mu.Lock()
 	if c.authCancel != nil {
@@ -230,7 +276,7 @@ func (c *Client) cancelMapSafely() {
 	c.mu.Lock()
 	defer c.mu.Unlock()
 
-	c.logf("cancelMapSafely: synced=%v", c.synced)
+	c.logf("[v1] cancelMapSafely: synced=%v", c.synced)
 
 	if c.inPollNetMap {
 		// received at least one netmap since the last
@@ -252,12 +298,12 @@ func (c *Client) cancelMapSafely() {
 		// request.
 		select {
 		case c.newMapCh <- struct{}{}:
-			c.logf("cancelMapSafely: wrote to channel")
+			c.logf("[v1] cancelMapSafely: wrote to channel")
 		default:
 			// if channel write failed, then there was already
 			// an outstanding newMapCh request. One is enough,
 			// since it'll always use the latest endpoints.
-			c.logf("cancelMapSafely: channel was full")
+			c.logf("[v1] cancelMapSafely: channel was full")
 		}
 	}
 }
@@ -268,22 +314,24 @@ func (c *Client) authRoutine() {
 
 	for {
 		c.mu.Lock()
-		c.logf("authRoutine: %s", c.state)
-		expiry := c.expiry
 		goal := c.loginGoal
 		ctx := c.authCtx
-		synced := c.synced
+		if goal != nil {
+			c.logf("authRoutine: %s; wantLoggedIn=%v", c.state, goal.wantLoggedIn)
+		} else {
+			c.logf("authRoutine: %s; goal=nil", c.state)
+		}
 		c.mu.Unlock()
 
 		select {
 		case <-c.quit:
-			c.logf("authRoutine: quit")
+			c.logf("[v1] authRoutine: quit")
 			return
 		default:
 		}
 
 		report := func(err error, msg string) {
-			c.logf("%s: %v", msg, err)
+			c.logf("[v1] %s: %v", msg, err)
 			err = fmt.Errorf("%s: %v", msg, err)
 			// don't send status updates for context errors,
 			// since context cancelation is always on purpose.
@@ -293,51 +341,13 @@ func (c *Client) authRoutine() {
 		}
 
 		if goal == nil {
-			// Wait for something interesting to happen
-			var exp <-chan time.Time
-			var expTimer *time.Timer
-			if expiry != nil && !expiry.IsZero() {
-				// if expiry is in the future, don't delay
-				// past that time.
-				// If it's in the past, then it's already
-				// being handled by someone, so no need to
-				// wake ourselves up again.
-				now := c.timeNow()
-				if expiry.Before(now) {
-					delay := expiry.Sub(now)
-					if delay > 5*time.Second {
-						delay = time.Second
-					}
-					expTimer = time.NewTimer(delay)
-					exp = expTimer.C
-				}
-			}
-			select {
-			case <-ctx.Done():
-				if expTimer != nil {
-					expTimer.Stop()
-				}
-				c.logf("authRoutine: context done.")
-			case <-exp:
-				// Unfortunately the key expiry isn't provided
-				// by the control server until mapRequest.
-				// So we have to do some hackery with c.expiry
-				// in here.
-				// TODO(apenwarr): add a key expiry field in RegisterResponse.
-				c.logf("authRoutine: key expiration check.")
-				if synced && expiry != nil && !expiry.IsZero() && expiry.Before(c.timeNow()) {
-					c.logf("Key expired; setting loggedIn=false.")
+			// Wait for user to Login or Logout.
+			<-ctx.Done()
+			c.logf("[v1] authRoutine: context done.")
+			continue
+		}
 
-					c.mu.Lock()
-					c.loginGoal = &LoginGoal{
-						wantLoggedIn: c.loggedIn,
-					}
-					c.loggedIn = false
-					c.expiry = nil
-					c.mu.Unlock()
-				}
-			}
-		} else if !goal.wantLoggedIn {
+		if !goal.wantLoggedIn {
 			err := c.direct.TryLogout(ctx)
 			if err != nil {
 				report(err, "TryLogout")
@@ -469,7 +479,7 @@ func (c *Client) mapRoutine() {
 		}
 
 		report := func(err error, msg string) {
-			c.logf("%s: %v", msg, err)
+			c.logf("[v1] %s: %v", msg, err)
 			err = fmt.Errorf("%s: %v", msg, err)
 			// don't send status updates for context errors,
 			// since context cancelation is always on purpose.
@@ -504,7 +514,7 @@ func (c *Client) mapRoutine() {
 
 				select {
 				case <-c.newMapCh:
-					c.logf("mapRoutine: new map request during PollNetMap. canceling.")
+					c.logf("[v1] mapRoutine: new map request during PollNetMap. canceling.")
 					c.cancelMapLocked()
 
 					// Don't emit this netmap; we're
@@ -526,7 +536,7 @@ func (c *Client) mapRoutine() {
 
 				c.mu.Unlock()
 
-				c.logf("mapRoutine: netmap received: %s", state)
+				c.logf("[v1] mapRoutine: netmap received: %s", state)
 				if stillAuthed {
 					c.sendStatus("mapRoutine-got-netmap", nil, "", nm)
 				}
@@ -580,7 +590,7 @@ func (c *Client) SetHostinfo(hi *tailcfg.Hostinfo) {
 	c.logf("Hostinfo: %v", hi)
 
 	// Send new Hostinfo to server
-	c.cancelMapSafely()
+	c.sendNewMapRequest()
 }
 
 func (c *Client) SetNetInfo(ni *tailcfg.NetInfo) {
@@ -588,13 +598,12 @@ func (c *Client) SetNetInfo(ni *tailcfg.NetInfo) {
 		panic("nil NetInfo")
 	}
 	if !c.direct.SetNetInfo(ni) {
-		c.logf("[unexpected] duplicate NetInfo: %v", ni)
 		return
 	}
 	c.logf("NetInfo: %v", ni)
 
 	// Send new Hostinfo (which includes NetInfo) to server
-	c.cancelMapSafely()
+	c.sendNewMapRequest()
 }
 
 func (c *Client) sendStatus(who string, err error, url string, nm *NetworkMap) {
@@ -607,7 +616,7 @@ func (c *Client) sendStatus(who string, err error, url string, nm *NetworkMap) {
 	c.inSendStatus++
 	c.mu.Unlock()
 
-	c.logf("sendStatus: %s: %v", who, state)
+	c.logf("[v1] sendStatus: %s: %v", who, state)
 
 	var p *Persist
 	var fin *empty.Message
@@ -671,7 +680,7 @@ func (c *Client) Logout() {
 func (c *Client) UpdateEndpoints(localPort uint16, endpoints []string) {
 	changed := c.direct.SetEndpoints(localPort, endpoints)
 	if changed {
-		c.cancelMapSafely()
+		c.sendNewMapRequest()
 	}
 }
 
@@ -700,7 +709,7 @@ func (c *Client) Shutdown() {
 
 // NodePublicKey returns the node public key currently in use. This is
 // used exclusively in tests.
-func (c *Client) TestOnlyNodePublicKey() wgcfg.Key {
+func (c *Client) TestOnlyNodePublicKey() wgkey.Key {
 	priv := c.direct.GetPersist()
 	return priv.PrivateNodeKey.Public()
 }

control/controlclient/controlclient_test.go

@@ -42,6 +42,11 @@ func TestStatusEqual(t *testing.T) {
 			&Status{},
 			false,
 		},
+		{
+			nil,
+			nil,
+			true,
+		},
 		{
 			&Status{},
 			&Status{},

control/controlclient/direct.go

@@ -31,11 +31,11 @@ import (
 	"sync/atomic"
 	"time"
 
-	"github.com/tailscale/wireguard-go/wgcfg"
 	"golang.org/x/crypto/nacl/box"
 	"golang.org/x/oauth2"
 	"inet.af/netaddr"
 	"tailscale.com/log/logheap"
+	"tailscale.com/net/dnscache"
 	"tailscale.com/net/netns"
 	"tailscale.com/net/tlsdial"
 	"tailscale.com/net/tshttpproxy"
@@ -43,7 +43,10 @@ import (
 	"tailscale.com/types/logger"
 	"tailscale.com/types/opt"
 	"tailscale.com/types/structs"
+	"tailscale.com/types/wgkey"
+	"tailscale.com/util/systemd"
 	"tailscale.com/version"
+	"tailscale.com/wgengine/filter"
 )
 
 type Persist struct {
@@ -58,10 +61,10 @@ type Persist struct {
 	// needed. This field should be considered read-only from GUI
 	// frontends. The real value should not be written back in
 	// this field, lest the frontend persist it to disk.
-	LegacyFrontendPrivateMachineKey wgcfg.PrivateKey `json:"PrivateMachineKey"`
+	LegacyFrontendPrivateMachineKey wgkey.Private `json:"PrivateMachineKey"`
 
-	PrivateNodeKey    wgcfg.PrivateKey
-	OldPrivateNodeKey wgcfg.PrivateKey // needed to request key rotation
+	PrivateNodeKey    wgkey.Private
+	OldPrivateNodeKey wgkey.Private // needed to request key rotation
 	Provider          string
 	LoginName         string
 }
@@ -82,7 +85,7 @@ func (p *Persist) Equals(p2 *Persist) bool {
 }
 
 func (p *Persist) Pretty() string {
-	var mk, ok, nk wgcfg.Key
+	var mk, ok, nk wgkey.Key
 	if !p.LegacyFrontendPrivateMachineKey.IsZero() {
 		mk = p.LegacyFrontendPrivateMachineKey.Public()
 	}
@@ -92,7 +95,7 @@ func (p *Persist) Pretty() string {
 	if !p.PrivateNodeKey.IsZero() {
 		nk = p.PrivateNodeKey.Public()
 	}
-	ss := func(k wgcfg.Key) string {
+	ss := func(k wgkey.Key) string {
 		if k.IsZero() {
 			return ""
 		}
@@ -104,22 +107,23 @@ func (p *Persist) Pretty() string {
 
 // Direct is the client that connects to a tailcontrol server for a node.
 type Direct struct {
-	httpc           *http.Client // HTTP client used to talk to tailcontrol
-	serverURL       string       // URL of the tailcontrol server
-	timeNow         func() time.Time
-	lastPrintMap    time.Time
-	newDecompressor func() (Decompressor, error)
-	keepAlive       bool
-	logf            logger.Logf
-	discoPubKey     tailcfg.DiscoKey
-	machinePrivKey  wgcfg.PrivateKey
-	debugFlags      []string
+	httpc                  *http.Client // HTTP client used to talk to tailcontrol
+	serverURL              string       // URL of the tailcontrol server
+	timeNow                func() time.Time
+	lastPrintMap           time.Time
+	newDecompressor        func() (Decompressor, error)
+	keepAlive              bool
+	logf                   logger.Logf
+	discoPubKey            tailcfg.DiscoKey
+	machinePrivKey         wgkey.Private
+	debugFlags             []string
+	keepSharerAndUserSplit bool
 
 	mu           sync.Mutex // mutex guards the following fields
-	serverKey    wgcfg.Key
+	serverKey    wgkey.Key
 	persist      Persist
 	authKey      string
-	tryingNewKey wgcfg.PrivateKey
+	tryingNewKey wgkey.Private
 	expiry       *time.Time
 	// hostinfo is mutated in-place while mu is held.
 	hostinfo      *tailcfg.Hostinfo // always non-nil
@@ -130,7 +134,7 @@ type Direct struct {
 
 type Options struct {
 	Persist           Persist           // initial persistent data
-	MachinePrivateKey wgcfg.PrivateKey  // the machine key to use
+	MachinePrivateKey wgkey.Private     // the machine key to use
 	ServerURL         string            // URL of the tailcontrol server
 	AuthKey           string            // optional node auth key for auto registration
 	TimeNow           func() time.Time  // time.Now implementation used by Client
@@ -141,6 +145,10 @@ type Options struct {
 	Logf              logger.Logf
 	HTTPTestClient    *http.Client // optional HTTP client to use (for tests only)
 	DebugFlags        []string     // debug settings to send to control
+
+	// KeepSharerAndUserSplit controls whether the client
+	// understands Node.Sharer. If false, the Sharer is mapped to the User.
+	KeepSharerAndUserSplit bool
 }
 
 type Decompressor interface {
@@ -172,28 +180,33 @@ func NewDirect(opts Options) (*Direct, error) {
 
 	httpc := opts.HTTPTestClient
 	if httpc == nil {
+		dnsCache := &dnscache.Resolver{
+			Forward:     dnscache.Get().Forward, // use default cache's forwarder
+			UseLastGood: true,
+		}
 		dialer := netns.NewDialer()
 		tr := http.DefaultTransport.(*http.Transport).Clone()
 		tr.Proxy = tshttpproxy.ProxyFromEnvironment
 		tshttpproxy.SetTransportGetProxyConnectHeader(tr)
-		tr.DialContext = dialer.DialContext
+		tr.DialContext = dnscache.Dialer(dialer.DialContext, dnsCache)
 		tr.ForceAttemptHTTP2 = true
 		tr.TLSClientConfig = tlsdial.Config(serverURL.Host, tr.TLSClientConfig)
 		httpc = &http.Client{Transport: tr}
 	}
 
 	c := &Direct{
-		httpc:           httpc,
-		machinePrivKey:  opts.MachinePrivateKey,
-		serverURL:       opts.ServerURL,
-		timeNow:         opts.TimeNow,
-		logf:            opts.Logf,
-		newDecompressor: opts.NewDecompressor,
-		keepAlive:       opts.KeepAlive,
-		persist:         opts.Persist,
-		authKey:         opts.AuthKey,
-		discoPubKey:     opts.DiscoPublicKey,
-		debugFlags:      opts.DebugFlags,
+		httpc:                  httpc,
+		machinePrivKey:         opts.MachinePrivateKey,
+		serverURL:              opts.ServerURL,
+		timeNow:                opts.TimeNow,
+		logf:                   opts.Logf,
+		newDecompressor:        opts.NewDecompressor,
+		keepAlive:              opts.KeepAlive,
+		persist:                opts.Persist,
+		authKey:                opts.AuthKey,
+		discoPubKey:            opts.DiscoPublicKey,
+		debugFlags:             opts.DebugFlags,
+		keepSharerAndUserSplit: opts.KeepSharerAndUserSplit,
 	}
 	if opts.Hostinfo == nil {
 		c.SetHostinfo(NewHostinfo())
@@ -303,6 +316,7 @@ func (c *Direct) doLoginOrRegen(ctx context.Context, t *oauth2.Token, flags Logi
 	if mustregen {
 		_, url, err = c.doLogin(ctx, t, flags, true, url)
 	}
+
 	return url, err
 }
 
@@ -323,6 +337,7 @@ func (c *Direct) doLogin(ctx context.Context, t *oauth2.Token, flags LoginFlags,
 
 	if expired {
 		c.logf("Old key expired -> regen=true")
+		systemd.Status("key expired; run 'tailscale up' to authenticate")
 		regen = true
 	}
 	if (flags & LoginInteractive) != 0 {
@@ -331,7 +346,7 @@ func (c *Direct) doLogin(ctx context.Context, t *oauth2.Token, flags LoginFlags,
 	}
 
 	c.logf("doLogin(regen=%v, hasUrl=%v)", regen, url != "")
-	if serverKey == (wgcfg.Key{}) {
+	if serverKey.IsZero() {
 		var err error
 		serverKey, err = loadServerKey(ctx, c.httpc, c.serverURL)
 		if err != nil {
@@ -343,12 +358,12 @@ func (c *Direct) doLogin(ctx context.Context, t *oauth2.Token, flags LoginFlags,
 		c.mu.Unlock()
 	}
 
-	var oldNodeKey wgcfg.Key
+	var oldNodeKey wgkey.Key
 	if url != "" {
 	} else if regen || persist.PrivateNodeKey.IsZero() {
 		c.logf("Generating a new nodekey.")
 		persist.OldPrivateNodeKey = persist.PrivateNodeKey
-		key, err := wgcfg.NewPrivateKey()
+		key, err := wgkey.NewPrivate()
 		if err != nil {
 			c.logf("login keygen: %v", err)
 			return regen, url, err
@@ -512,6 +527,18 @@ func inTest() bool { return flag.Lookup("test.v") != nil }
 // maxPolls is how many network maps to download; common values are 1
 // or -1 (to keep a long-poll query open to the server).
 func (c *Direct) PollNetMap(ctx context.Context, maxPolls int, cb func(*NetworkMap)) error {
+	return c.sendMapRequest(ctx, maxPolls, cb)
+}
+
+// SendLiteMapUpdate makes a /map request to update the server of our latest state,
+// but does not fetch anything. It returns an error if the server did not return a
+// successful 200 OK response.
+func (c *Direct) SendLiteMapUpdate(ctx context.Context) error {
+	return c.sendMapRequest(ctx, 1, nil)
+}
+
+// cb nil means to omit peers.
+func (c *Direct) sendMapRequest(ctx context.Context, maxPolls int, cb func(*NetworkMap)) error {
 	c.mu.Lock()
 	persist := c.persist
 	serverURL := c.serverURL
@@ -528,15 +555,17 @@ func (c *Direct) PollNetMap(ctx context.Context, maxPolls int, cb func(*NetworkM
 	}
 
 	allowStream := maxPolls != 1
-	c.logf("PollNetMap: stream=%v :%v ep=%v", allowStream, localPort, ep)
+	c.logf("[v1] PollNetMap: stream=%v :%v ep=%v", allowStream, localPort, ep)
 
 	vlogf := logger.Discard
 	if Debug.NetMap {
+		// TODO(bradfitz): update this to use "[v2]" prefix perhaps? but we don't
+		// want to upload it always.
 		vlogf = c.logf
 	}
 
 	request := tailcfg.MapRequest{
-		Version:    5,
+		Version:    tailcfg.CurrentMapRequestVersion,
 		KeepAlive:  c.keepAlive,
 		NodeKey:    tailcfg.NodeKey(persist.PrivateNodeKey.Public()),
 		DiscoKey:   c.discoPubKey,
@@ -544,6 +573,7 @@ func (c *Direct) PollNetMap(ctx context.Context, maxPolls int, cb func(*NetworkM
 		Stream:     allowStream,
 		Hostinfo:   hostinfo,
 		DebugFlags: c.debugFlags,
+		OmitPeers:  cb == nil,
 	}
 	if hostinfo != nil && ipForwardingBroken(hostinfo.RoutableIPs) {
 		old := request.DebugFlags
@@ -596,6 +626,11 @@ func (c *Direct) PollNetMap(ctx context.Context, maxPolls int, cb func(*NetworkM
 	}
 	defer res.Body.Close()
 
+	if cb == nil {
+		io.Copy(ioutil.Discard, res.Body)
+		return nil
+	}
+
 	// If we go more than pollTimeout without hearing from the server,
 	// end the long poll. We should be receiving a keep alive ping
 	// every minute.
@@ -631,6 +666,8 @@ func (c *Direct) PollNetMap(ctx context.Context, maxPolls int, cb func(*NetworkM
 
 	var lastDERPMap *tailcfg.DERPMap
 	var lastUserProfile = map[tailcfg.UserID]tailcfg.UserProfile{}
+	var lastParsedPacketFilter []filter.Match
+	var collectServices bool
 
 	// If allowStream, then the server will use an HTTP long poll to
 	// return incremental results. There is always one response right
@@ -671,7 +708,7 @@ func (c *Direct) PollNetMap(ctx context.Context, maxPolls int, cb func(*NetworkM
 		case timeoutReset <- struct{}{}:
 			vlogf("netmap: sent timer reset")
 		case <-ctx.Done():
-			c.logf("netmap: not resetting timer; context done: %v", ctx.Err())
+			c.logf("[v1] netmap: not resetting timer; context done: %v", ctx.Err())
 			return ctx.Err()
 		}
 		if resp.KeepAlive {
@@ -708,23 +745,40 @@ func (c *Direct) PollNetMap(ctx context.Context, maxPolls int, cb func(*NetworkM
 			resp.Peers = filtered
 		}
 
+		if pf := resp.PacketFilter; pf != nil {
+			lastParsedPacketFilter = c.parsePacketFilter(pf)
+		}
+
+		if v, ok := resp.CollectServices.Get(); ok {
+			collectServices = v
+		}
+
+		// Get latest localPort. This might've changed if
+		// a lite map update occured meanwhile. This only affects
+		// the end-to-end test.
+		// TODO(bradfitz): remove the NetworkMap.LocalPort field entirely.
+		c.mu.Lock()
+		localPort = c.localPort
+		c.mu.Unlock()
+
 		nm := &NetworkMap{
-			NodeKey:      tailcfg.NodeKey(persist.PrivateNodeKey.Public()),
-			PrivateKey:   persist.PrivateNodeKey,
-			MachineKey:   machinePubKey,
-			Expiry:       resp.Node.KeyExpiry,
-			Name:         resp.Node.Name,
-			Addresses:    resp.Node.Addresses,
-			Peers:        resp.Peers,
-			LocalPort:    localPort,
-			User:         resp.Node.User,
-			UserProfiles: make(map[tailcfg.UserID]tailcfg.UserProfile),
-			Domain:       resp.Domain,
-			DNS:          resp.DNSConfig,
-			Hostinfo:     resp.Node.Hostinfo,
-			PacketFilter: c.parsePacketFilter(resp.PacketFilter),
-			DERPMap:      lastDERPMap,
-			Debug:        resp.Debug,
+			NodeKey:         tailcfg.NodeKey(persist.PrivateNodeKey.Public()),
+			PrivateKey:      persist.PrivateNodeKey,
+			MachineKey:      machinePubKey,
+			Expiry:          resp.Node.KeyExpiry,
+			Name:            resp.Node.Name,
+			Addresses:       resp.Node.Addresses,
+			Peers:           resp.Peers,
+			LocalPort:       localPort,
+			User:            resp.Node.User,
+			UserProfiles:    make(map[tailcfg.UserID]tailcfg.UserProfile),
+			Domain:          resp.Domain,
+			DNS:             resp.DNSConfig,
+			Hostinfo:        resp.Node.Hostinfo,
+			PacketFilter:    lastParsedPacketFilter,
+			CollectServices: collectServices,
+			DERPMap:         lastDERPMap,
+			Debug:           resp.Debug,
 		}
 		addUserProfile := func(userID tailcfg.UserID) {
 			if _, dup := nm.UserProfiles[userID]; dup {
@@ -737,6 +791,13 @@ func (c *Direct) PollNetMap(ctx context.Context, maxPolls int, cb func(*NetworkM
 		}
 		addUserProfile(nm.User)
 		for _, peer := range resp.Peers {
+			if !peer.Sharer.IsZero() {
+				if c.keepSharerAndUserSplit {
+					addUserProfile(peer.Sharer)
+				} else {
+					peer.User = peer.Sharer
+				}
+			}
 			addUserProfile(peer.User)
 		}
 		if resp.Node.MachineAuthorized {
@@ -745,7 +806,7 @@ func (c *Direct) PollNetMap(ctx context.Context, maxPolls int, cb func(*NetworkM
 			nm.MachineStatus = tailcfg.MachineUnauthorized
 		}
 		if len(resp.DNS) > 0 {
-			nm.DNS.Nameservers = wgIPToNetaddr(resp.DNS)
+			nm.DNS.Nameservers = resp.DNS
 		}
 		if len(resp.SearchPaths) > 0 {
 			nm.DNS.Domains = resp.SearchPaths
@@ -762,7 +823,7 @@ func (c *Direct) PollNetMap(ctx context.Context, maxPolls int, cb func(*NetworkM
 		now := c.timeNow()
 		if now.Sub(c.lastPrintMap) >= 5*time.Minute {
 			c.lastPrintMap = now
-			c.logf("new network map[%d]:\n%s", i, nm.Concise())
+			c.logf("[v1] new network map[%d]:\n%s", i, nm.Concise())
 		}
 
 		c.mu.Lock()
@@ -777,7 +838,7 @@ func (c *Direct) PollNetMap(ctx context.Context, maxPolls int, cb func(*NetworkM
 	return nil
 }
 
-func decode(res *http.Response, v interface{}, serverKey *wgcfg.Key, mkey *wgcfg.PrivateKey) error {
+func decode(res *http.Response, v interface{}, serverKey *wgkey.Key, mkey *wgkey.Private) error {
 	defer res.Body.Close()
 	msg, err := ioutil.ReadAll(io.LimitReader(res.Body, 1<<20))
 	if err != nil {
@@ -832,7 +893,7 @@ func (c *Direct) decodeMsg(msg []byte, v interface{}) error {
 
 }
 
-func decodeMsg(msg []byte, v interface{}, serverKey *wgcfg.Key, mkey *wgcfg.PrivateKey) error {
+func decodeMsg(msg []byte, v interface{}, serverKey *wgkey.Key, mkey *wgkey.Private) error {
 	decrypted, err := decryptMsg(msg, serverKey, mkey)
 	if err != nil {
 		return err
@@ -846,7 +907,7 @@ func decodeMsg(msg []byte, v interface{}, serverKey *wgcfg.Key, mkey *wgcfg.Priv
 	return nil
 }
 
-func decryptMsg(msg []byte, serverKey *wgcfg.Key, mkey *wgcfg.PrivateKey) ([]byte, error) {
+func decryptMsg(msg []byte, serverKey *wgkey.Key, mkey *wgkey.Private) ([]byte, error) {
 	var nonce [24]byte
 	if len(msg) < len(nonce)+1 {
 		return nil, fmt.Errorf("response missing nonce, len=%d", len(msg))
@@ -862,7 +923,7 @@ func decryptMsg(msg []byte, serverKey *wgcfg.Key, mkey *wgcfg.PrivateKey) ([]byt
 	return decrypted, nil
 }
 
-func encode(v interface{}, serverKey *wgcfg.Key, mkey *wgcfg.PrivateKey) ([]byte, error) {
+func encode(v interface{}, serverKey *wgkey.Key, mkey *wgkey.Private) ([]byte, error) {
 	b, err := json.Marshal(v)
 	if err != nil {
 		return nil, err
@@ -881,42 +942,31 @@ func encode(v interface{}, serverKey *wgcfg.Key, mkey *wgcfg.PrivateKey) ([]byte
 	return msg, nil
 }
 
-func loadServerKey(ctx context.Context, httpc *http.Client, serverURL string) (wgcfg.Key, error) {
+func loadServerKey(ctx context.Context, httpc *http.Client, serverURL string) (wgkey.Key, error) {
 	req, err := http.NewRequest("GET", serverURL+"/key", nil)
 	if err != nil {
-		return wgcfg.Key{}, fmt.Errorf("create control key request: %v", err)
+		return wgkey.Key{}, fmt.Errorf("create control key request: %v", err)
 	}
 	req = req.WithContext(ctx)
 	res, err := httpc.Do(req)
 	if err != nil {
-		return wgcfg.Key{}, fmt.Errorf("fetch control key: %v", err)
+		return wgkey.Key{}, fmt.Errorf("fetch control key: %v", err)
 	}
 	defer res.Body.Close()
 	b, err := ioutil.ReadAll(io.LimitReader(res.Body, 1<<16))
 	if err != nil {
-		return wgcfg.Key{}, fmt.Errorf("fetch control key response: %v", err)
+		return wgkey.Key{}, fmt.Errorf("fetch control key response: %v", err)
 	}
 	if res.StatusCode != 200 {
-		return wgcfg.Key{}, fmt.Errorf("fetch control key: %d: %s", res.StatusCode, string(b))
+		return wgkey.Key{}, fmt.Errorf("fetch control key: %d: %s", res.StatusCode, string(b))
 	}
-	key, err := wgcfg.ParseHexKey(string(b))
+	key, err := wgkey.ParseHex(string(b))
 	if err != nil {
-		return wgcfg.Key{}, fmt.Errorf("fetch control key: %v", err)
+		return wgkey.Key{}, fmt.Errorf("fetch control key: %v", err)
 	}
 	return key, nil
 }
 
-func wgIPToNetaddr(ips []wgcfg.IP) (ret []netaddr.IP) {
-	for _, ip := range ips {
-		nip, ok := netaddr.FromStdIP(ip.IP())
-		if !ok {
-			panic(fmt.Sprintf("conversion of %s from wgcfg to netaddr IP failed", ip))
-		}
-		ret = append(ret, nip.Unmap())
-	}
-	return ret
-}
-
 // Debug contains temporary internal-only debug knobs.
 // They're unexported to not draw attention to them.
 var Debug = initDebug()
@@ -1075,11 +1125,12 @@ func TrimWGConfig() opt.Bool {
 // and will definitely not work for the routes provided.
 //
 // It should not return false positives.
-func ipForwardingBroken(routes []wgcfg.CIDR) bool {
+func ipForwardingBroken(routes []netaddr.IPPrefix) bool {
 	if len(routes) == 0 {
 		// Nothing to route, so no need to warn.
 		return false
 	}
+
 	if runtime.GOOS != "linux" {
 		// We only do subnet routing on Linux for now.
 		// It might work on darwin/macOS when building from source, so
@@ -1087,17 +1138,57 @@ func ipForwardingBroken(routes []wgcfg.CIDR) bool {
 		// already in the admin panel.
 		return false
 	}
-	out, err := ioutil.ReadFile("/proc/sys/net/ipv4/ip_forward")
-	if err != nil {
-		// Try another way.
-		out, err = exec.Command("sysctl", "-n", "net.ipv4.ip_forward").Output()
+
+	v4Routes, v6Routes := false, false
+	for _, r := range routes {
+		if r.IP.Is4() {
+			v4Routes = true
+		} else {
+			v6Routes = true
+		}
 	}
-	if err != nil {
-		// Oh well, we tried. This is just for debugging.
-		// We don't want false positives.
-		// TODO: maybe we want a different warning for inability to check?
-		return false
+
+	if v4Routes {
+		out, err := ioutil.ReadFile("/proc/sys/net/ipv4/ip_forward")
+		if err != nil {
+			// Try another way.
+			out, err = exec.Command("sysctl", "-n", "net.ipv4.ip_forward").Output()
+		}
+		if err != nil {
+			// Oh well, we tried. This is just for debugging.
+			// We don't want false positives.
+			// TODO: maybe we want a different warning for inability to check?
+			return false
+		}
+		if strings.TrimSpace(string(out)) == "0" {
+			return true
+		}
 	}
-	return strings.TrimSpace(string(out)) == "0"
-	// TODO: also check IPv6 if 'routes' contains any IPv6 routes
+	if v6Routes {
+		// Note: you might be wondering why we check only the state of
+		// conf.all.forwarding, rather than per-interface forwarding
+		// configuration. According to kernel documentation, it seems
+		// that to actually forward packets, you need to enable
+		// forwarding globally, and the per-interface forwarding
+		// setting only alters other things such as how router
+		// advertisements are handled. The kernel itself warns that
+		// enabling forwarding per-interface and not globally will
+		// probably not work, so I feel okay calling those configs
+		// broken until we have proof otherwise.
+		out, err := ioutil.ReadFile("/proc/sys/net/ipv6/conf/all/forwarding")
+		if err != nil {
+			out, err = exec.Command("sysctl", "-n", "net.ipv6.conf.all.forwarding").Output()
+		}
+		if err != nil {
+			// Oh well, we tried. This is just for debugging.
+			// We don't want false positives.
+			// TODO: maybe we want a different warning for inability to check?
+			return false
+		}
+		if strings.TrimSpace(string(out)) == "0" {
+			return true
+		}
+	}
+
+	return false
 }

control/controlclient/direct_test.go

@@ -11,6 +11,7 @@ import (
 	"testing"
 
 	"tailscale.com/tailcfg"
+	"tailscale.com/types/wgkey"
 )
 
 func TestUndeltaPeers(t *testing.T) {
@@ -91,3 +92,67 @@ func formatNodes(nodes []*tailcfg.Node) string {
 	}
 	return sb.String()
 }
+
+func TestNewDirect(t *testing.T) {
+	hi := NewHostinfo()
+	ni := tailcfg.NetInfo{LinkType: "wired"}
+	hi.NetInfo = &ni
+
+	key, err := wgkey.NewPrivate()
+	if err != nil {
+		t.Error(err)
+	}
+	opts := Options{ServerURL: "https://example.com", MachinePrivateKey: key, Hostinfo: hi}
+	c, err := NewDirect(opts)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if c.serverURL != opts.ServerURL {
+		t.Errorf("c.serverURL got %v want %v", c.serverURL, opts.ServerURL)
+	}
+
+	if !hi.Equal(c.hostinfo) {
+		t.Errorf("c.hostinfo got %v want %v", c.hostinfo, hi)
+	}
+
+	changed := c.SetNetInfo(&ni)
+	if changed {
+		t.Errorf("c.SetNetInfo(ni) want false got %v", changed)
+	}
+	ni = tailcfg.NetInfo{LinkType: "wifi"}
+	changed = c.SetNetInfo(&ni)
+	if !changed {
+		t.Errorf("c.SetNetInfo(ni) want true got %v", changed)
+	}
+
+	changed = c.SetHostinfo(hi)
+	if changed {
+		t.Errorf("c.SetHostinfo(hi) want false got %v", changed)
+	}
+	hi = NewHostinfo()
+	hi.Hostname = "different host name"
+	changed = c.SetHostinfo(hi)
+	if !changed {
+		t.Errorf("c.SetHostinfo(hi) want true got %v", changed)
+	}
+
+	endpoints := []string{"1", "2", "3"}
+	changed = c.newEndpoints(12, endpoints)
+	if !changed {
+		t.Errorf("c.newEndpoints(12) want true got %v", changed)
+	}
+	changed = c.newEndpoints(12, endpoints)
+	if changed {
+		t.Errorf("c.newEndpoints(12) want false got %v", changed)
+	}
+	changed = c.newEndpoints(13, endpoints)
+	if !changed {
+		t.Errorf("c.newEndpoints(13) want true got %v", changed)
+	}
+	endpoints = []string{"4", "5", "6"}
+	changed = c.newEndpoints(13, endpoints)
+	if !changed {
+		t.Errorf("c.newEndpoints(13) want true got %v", changed)
+	}
+}

control/controlclient/filter.go

@@ -9,9 +9,9 @@ import (
 	"tailscale.com/wgengine/filter"
 )
 
-// Parse a backward-compatible FilterRule used by control's wire format,
-// producing the most current filter.Matches format.
-func (c *Direct) parsePacketFilter(pf []tailcfg.FilterRule) filter.Matches {
+// Parse a backward-compatible FilterRule used by control's wire
+// format, producing the most current filter format.
+func (c *Direct) parsePacketFilter(pf []tailcfg.FilterRule) []filter.Match {
 	mm, err := filter.MatchesFromFilterRules(pf)
 	if err != nil {
 		c.logf("parsePacketFilter: %s\n", err)

control/controlclient/hostinfo_linux.go

@@ -73,7 +73,7 @@ func osVersionLinux() string {
 			return fmt.Sprintf("%s%s", bytes.TrimSpace(cr), attr)
 		}
 		fallthrough
-	case "fedora", "rhel", "alpine":
+	case "fedora", "rhel", "alpine", "nixos":
 		// Their PRETTY_NAME is fine as-is for all versions I tested.
 		fallthrough
 	default:

control/controlclient/netmap.go

@@ -14,8 +14,11 @@ import (
 	"time"
 
 	"github.com/tailscale/wireguard-go/wgcfg"
+	"inet.af/netaddr"
 	"tailscale.com/tailcfg"
 	"tailscale.com/types/logger"
+	"tailscale.com/types/wgkey"
+	"tailscale.com/util/dnsname"
 	"tailscale.com/wgengine/filter"
 )
 
@@ -23,18 +26,24 @@ type NetworkMap struct {
 	// Core networking
 
 	NodeKey    tailcfg.NodeKey
-	PrivateKey wgcfg.PrivateKey
+	PrivateKey wgkey.Private
 	Expiry     time.Time
 	// Name is the DNS name assigned to this node.
 	Name          string
-	Addresses     []wgcfg.CIDR
+	Addresses     []netaddr.IPPrefix
 	LocalPort     uint16 // used for debugging
 	MachineStatus tailcfg.MachineStatus
 	MachineKey    tailcfg.MachineKey
 	Peers         []*tailcfg.Node // sorted by Node.ID
 	DNS           tailcfg.DNSConfig
 	Hostinfo      tailcfg.Hostinfo
-	PacketFilter  filter.Matches
+	PacketFilter  []filter.Match
+
+	// CollectServices reports whether this node's Tailnet has
+	// requested that info about services be included in HostInfo.
+	// If set, Hostinfo.ShieldsUp blocks services collection; that
+	// takes precedence over this field.
+	CollectServices bool
 
 	// DERPMap is the last DERP server map received. It's reused
 	// between updates and should not be modified.
@@ -54,7 +63,30 @@ type NetworkMap struct {
 	// TODO(crawshaw): Capabilities []tailcfg.Capability
 }
 
-func (nm NetworkMap) String() string {
+// MagicDNSSuffix returns the domain's MagicDNS suffix, or empty if none.
+// If non-empty, it will neither start nor end with a period.
+func (nm *NetworkMap) MagicDNSSuffix() string {
+	searchPathUsedAsDNSSuffix := func(suffix string) bool {
+		if dnsname.HasSuffix(nm.Name, suffix) {
+			return true
+		}
+		for _, p := range nm.Peers {
+			if dnsname.HasSuffix(p.Name, suffix) {
+				return true
+			}
+		}
+		return false
+	}
+
+	for _, d := range nm.DNS.Domains {
+		if searchPathUsedAsDNSSuffix(d) {
+			return strings.Trim(d, ".")
+		}
+	}
+	return ""
+}
+
+func (nm *NetworkMap) String() string {
 	return nm.Concise()
 }
 
@@ -240,7 +272,7 @@ const EndpointDiscoSuffix = ".disco.tailscale:12345"
 func (nm *NetworkMap) WGCfg(logf logger.Logf, flags WGConfigFlags) (*wgcfg.Config, error) {
 	cfg := &wgcfg.Config{
 		Name:       "tailscale",
-		PrivateKey: nm.PrivateKey,
+		PrivateKey: wgcfg.PrivateKey(nm.PrivateKey),
 		Addresses:  nm.Addresses,
 		ListenPort: nm.LocalPort,
 		Peers:      make([]wgcfg.Peer, 0, len(nm.Peers)),
@@ -266,7 +298,7 @@ func (nm *NetworkMap) WGCfg(logf logger.Logf, flags WGConfigFlags) (*wgcfg.Confi
 			if err := appendEndpoint(cpeer, fmt.Sprintf("%x%s", peer.DiscoKey[:], EndpointDiscoSuffix)); err != nil {
 				return nil, err
 			}
-			cpeer.Endpoints = []wgcfg.Endpoint{{Host: fmt.Sprintf("%x.disco.tailscale", peer.DiscoKey[:]), Port: 12345}}
+			cpeer.Endpoints = fmt.Sprintf("%x.disco.tailscale:12345", peer.DiscoKey[:])
 		} else {
 			if err := appendEndpoint(cpeer, peer.DERP); err != nil {
 				return nil, err
@@ -278,14 +310,14 @@ func (nm *NetworkMap) WGCfg(logf logger.Logf, flags WGConfigFlags) (*wgcfg.Confi
 			}
 		}
 		for _, allowedIP := range peer.AllowedIPs {
-			if allowedIP.Mask == 0 {
+			if allowedIP.Bits == 0 {
 				if (flags & AllowDefaultRoute) == 0 {
-					logf("wgcfg: %v skipping default route", peer.Key.ShortString())
+					logf("[v1] wgcfg: %v skipping default route", peer.Key.ShortString())
 					continue
 				}
 			} else if cidrIsSubnet(peer, allowedIP) {
 				if (flags & AllowSubnetRoutes) == 0 {
-					logf("wgcfg: %v skipping subnet route", peer.Key.ShortString())
+					logf("[v1] wgcfg: %v skipping subnet route", peer.Key.ShortString())
 					continue
 				}
 			}
@@ -298,17 +330,11 @@ func (nm *NetworkMap) WGCfg(logf logger.Logf, flags WGConfigFlags) (*wgcfg.Confi
 
 // cidrIsSubnet reports whether cidr is a non-default-route subnet
 // exported by node that is not one of its own self addresses.
-func cidrIsSubnet(node *tailcfg.Node, cidr wgcfg.CIDR) bool {
-	if cidr.Mask == 0 {
+func cidrIsSubnet(node *tailcfg.Node, cidr netaddr.IPPrefix) bool {
+	if cidr.Bits == 0 {
 		return false
 	}
-	if cidr.Mask < 32 {
-		// Fast path for IPv4, to avoid loop below.
-		//
-		// TODO: if cidr.IP is an IPv6 address, we could do "< 128"
-		// to avoid the range over node.Addresses. Or we could
-		// just remove this fast path and unconditionally do the range
-		// loop.
+	if !cidr.IsSingleIP() {
 		return true
 	}
 	for _, selfCIDR := range node.Addresses {
@@ -323,15 +349,18 @@ func appendEndpoint(peer *wgcfg.Peer, epStr string) error {
 	if epStr == "" {
 		return nil
 	}
-	host, port, err := net.SplitHostPort(epStr)
+	_, port, err := net.SplitHostPort(epStr)
 	if err != nil {
 		return fmt.Errorf("malformed endpoint %q for peer %v", epStr, peer.PublicKey.ShortString())
 	}
-	port16, err := strconv.ParseUint(port, 10, 16)
+	_, err = strconv.ParseUint(port, 10, 16)
 	if err != nil {
 		return fmt.Errorf("invalid port in endpoint %q for peer %v", epStr, peer.PublicKey.ShortString())
 	}
-	peer.Endpoints = append(peer.Endpoints, wgcfg.Endpoint{Host: host, Port: uint16(port16)})
+	if peer.Endpoints != "" {
+		peer.Endpoints += ","
+	}
+	peer.Endpoints += epStr
 	return nil
 }
 
@@ -351,7 +380,7 @@ func eqStringsIgnoreNil(a, b []string) bool {
 
 // eqCIDRsIgnoreNil reports whether a and b have the same length and
 // contents, but ignore whether a or b are nil.
-func eqCIDRsIgnoreNil(a, b []wgcfg.CIDR) bool {
+func eqCIDRsIgnoreNil(a, b []netaddr.IPPrefix) bool {
 	if len(a) != len(b) {
 		return false
 	}

control/controlclient/netmap_test.go

@@ -6,9 +6,10 @@ package controlclient
 
 import (
 	"encoding/hex"
+	"encoding/json"
 	"testing"
 
-	"github.com/tailscale/wireguard-go/wgcfg"
+	"inet.af/netaddr"
 	"tailscale.com/tailcfg"
 )
 
@@ -250,7 +251,7 @@ func TestConciseDiffFrom(t *testing.T) {
 						DERP:       "127.3.3.40:2",
 						Endpoints:  []string{"192.168.0.100:41641", "1.1.1.1:41641"},
 						DiscoKey:   testDiscoKey("f00f00f00f"),
-						AllowedIPs: []wgcfg.CIDR{{IP: wgcfg.IPv4(100, 102, 103, 104), Mask: 32}},
+						AllowedIPs: []netaddr.IPPrefix{{IP: netaddr.IPv4(100, 102, 103, 104), Bits: 32}},
 					},
 				},
 			},
@@ -263,7 +264,7 @@ func TestConciseDiffFrom(t *testing.T) {
 						DERP:       "127.3.3.40:2",
 						Endpoints:  []string{"192.168.0.100:41641", "1.1.1.1:41641"},
 						DiscoKey:   testDiscoKey("ba4ba4ba4b"),
-						AllowedIPs: []wgcfg.CIDR{{IP: wgcfg.IPv4(100, 102, 103, 104), Mask: 32}},
+						AllowedIPs: []netaddr.IPPrefix{{IP: netaddr.IPv4(100, 102, 103, 104), Bits: 32}},
 					},
 				},
 			},
@@ -282,3 +283,15 @@ func TestConciseDiffFrom(t *testing.T) {
 		})
 	}
 }
+
+func TestNewHostinfo(t *testing.T) {
+	hi := NewHostinfo()
+	if hi == nil {
+		t.Fatal("no Hostinfo")
+	}
+	j, err := json.MarshalIndent(hi, "  ", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Logf("Got: %s", j)
+}

control/controlclient/persist_test.go

@@ -8,7 +8,7 @@ import (
 	"reflect"
 	"testing"
 
-	"github.com/tailscale/wireguard-go/wgcfg"
+	"tailscale.com/types/wgkey"
 )
 
 func TestPersistEqual(t *testing.T) {
@@ -18,8 +18,8 @@ func TestPersistEqual(t *testing.T) {
 			have, persistHandles)
 	}
 
-	newPrivate := func() wgcfg.PrivateKey {
-		k, err := wgcfg.NewPrivateKey()
+	newPrivate := func() wgkey.Private {
+		k, err := wgkey.NewPrivate()
 		if err != nil {
 			panic(err)
 		}

derp/derphttp/derphttp_client.go

@@ -358,7 +358,7 @@ func (c *Client) dialURL(ctx context.Context) (net.Conn, error) {
 	dialer := netns.NewDialer()
 
 	if c.DNSCache != nil {
-		ip, err := c.DNSCache.LookupIP(ctx, host)
+		ip, _, err := c.DNSCache.LookupIP(ctx, host)
 		if err == nil {
 			hostOrIP = ip.String()
 		}

go.mod

@@ -1,6 +1,6 @@
 module tailscale.com
 
-go 1.14
+go 1.15
 
 require (
 	github.com/alexbrainman/sspi v0.0.0-20180613141037-e580b900e9f5
@@ -12,30 +12,33 @@ require (
 	github.com/go-multierror/multierror v1.0.2
 	github.com/go-ole/go-ole v1.2.4
 	github.com/godbus/dbus/v5 v5.0.3
-	github.com/golang/groupcache v0.0.0-20200121045136-8c9f03a8e57e
-	github.com/google/go-cmp v0.4.0
+	github.com/golang/protobuf v1.4.2 // indirect
+	github.com/google/go-cmp v0.5.4
 	github.com/goreleaser/nfpm v1.1.10
-	github.com/jsimonetti/rtnetlink v0.0.0-20200117123717-f846d4f6c1f4
+	github.com/jsimonetti/rtnetlink v0.0.0-20201216134343-bde56ed16391
 	github.com/klauspost/compress v1.10.10
-	github.com/kr/pty v1.1.1
-	github.com/mdlayher/netlink v1.1.0
+	github.com/kr/pty v1.1.4-0.20190131011033-7dc38fb350b1
+	github.com/mdlayher/netlink v1.2.0
+	github.com/mdlayher/sdnotify v0.0.0-20200625151349-e4a4f32afc4a
 	github.com/miekg/dns v1.1.30
 	github.com/pborman/getopt v0.0.0-20190409184431-ee0cd42419d3
 	github.com/peterbourgon/ff/v2 v2.0.0
-	github.com/tailscale/depaware v0.0.0-20201003033024-5d95aab075be
-	github.com/tailscale/wireguard-go v0.0.0-20201021041318-a6168fd06b3f
+	github.com/tailscale/depaware v0.0.0-20201214215404-77d1e9757027
+	github.com/tailscale/wireguard-go v0.0.0-20210116013233-4cd297ed5a7d
 	github.com/tcnksm/go-httpstat v0.2.0
 	github.com/toqueteos/webbrowser v1.2.0
-	go4.org/mem v0.0.0-20200706164138-185c595c3ecc
-	golang.org/x/crypto v0.0.0-20200709230013-948cd5f35899
-	golang.org/x/net v0.0.0-20200822124328-c89045814202
+	go4.org/mem v0.0.0-20201119185036-c04c5a6ff174
+	golang.org/x/crypto v0.0.0-20201124201722-c8d3bf9c5392
+	golang.org/x/net v0.0.0-20201216054612-986b41b23924
 	golang.org/x/oauth2 v0.0.0-20200107190931-bf48bf16ab8d
-	golang.org/x/sync v0.0.0-20200625203802-6e8e738ad208
-	golang.org/x/sys v0.0.0-20200812155832-6a926be9bd1d
+	golang.org/x/sync v0.0.0-20201020160332-67f06af15bc9
+	golang.org/x/sys v0.0.0-20201218084310-7d0127a74742
+	golang.org/x/term v0.0.0-20201207232118-ee85cb95a76b
 	golang.org/x/time v0.0.0-20191024005414-555d28b269f0
-	golang.org/x/tools v0.0.0-20201002184944-ecd9fd270d5d
-	golang.zx2c4.com/wireguard/windows v0.1.2-0.20201004085714-dd60d0447f81
-	honnef.co/go/tools v0.0.1-2020.1.4
-	inet.af/netaddr v0.0.0-20200810144936-56928fe48a98
+	golang.org/x/tools v0.0.0-20201211185031-d93e913c1a58
+	golang.zx2c4.com/wireguard/windows v0.1.2-0.20201113162609-9b85be97fdf8
+	gvisor.dev/gvisor v0.0.0-20210111185822-3ff3110fcdd6
+	honnef.co/go/tools v0.1.0
+	inet.af/netaddr v0.0.0-20210105212526-648fbc18a69d
 	rsc.io/goversion v1.2.0
 )

go.sum

@@ -1,8 +1,34 @@
+bazil.org/fuse v0.0.0-20160811212531-371fbbdaa898/go.mod h1:Xbm+BRKSBEpa4q4hTSxohYNQpsxXPbPry4JJWOB3LB8=
+cloud.google.com/go v0.26.0/go.mod h1:aQUYkXzVsufM+DwF1aE+0xfcU+56JwCaLick0ClmMTw=
 cloud.google.com/go v0.34.0/go.mod h1:aQUYkXzVsufM+DwF1aE+0xfcU+56JwCaLick0ClmMTw=
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+k8s.io/utils v0.0.0-20190801114015-581e00157fb1/go.mod h1:sZAwmy6armz5eXlNoLmJcl4F1QuKu7sr+mFQ0byX7Ew=
+rsc.io/binaryregexp v0.2.0/go.mod h1:qTv7/COck+e2FymRvadv62gMdZztPaShugOCi3I+8D8=
 rsc.io/goversion v1.2.0 h1:SPn+NLTiAG7w30IRK/DKp1BjvpWabYgxlLp/+kx5J8w=
 rsc.io/goversion v1.2.0/go.mod h1:Eih9y/uIBS3ulggl7KNJ09xGSLcuNaLgmvvqa07sgfo=
+sigs.k8s.io/structured-merge-diff v0.0.0-20190525122527-15d366b2352e/go.mod h1:wWxsB5ozmmv/SG7nM11ayaAW51xMvak/t1r0CSlcokI=
+sigs.k8s.io/yaml v1.1.0/go.mod h1:UJmg0vDUVViEyp3mgSv9WPwZCDxu4rQW1olrI1uml+o=

internal/deepprint/deepprint_test.go

@@ -37,16 +37,11 @@ func getVal() []interface{} {
 	return []interface{}{
 		&wgcfg.Config{
 			Name:       "foo",
-			Addresses:  []wgcfg.CIDR{{Mask: 5, IP: wgcfg.IP{Addr: [16]byte{3: 3}}}},
+			Addresses:  []netaddr.IPPrefix{{Bits: 5, IP: netaddr.IPFrom16([16]byte{3: 3})}},
 			ListenPort: 5,
 			Peers: []wgcfg.Peer{
 				{
-					Endpoints: []wgcfg.Endpoint{
-						{
-							Host: "foo",
-							Port: 5,
-						},
-					},
+					Endpoints: "foo:5",
 				},
 			},
 		},

ipn/handle.go

@@ -8,8 +8,8 @@ import (
 	"sync"
 	"time"
 
-	"github.com/tailscale/wireguard-go/wgcfg"
 	"golang.org/x/oauth2"
+	"inet.af/netaddr"
 	"tailscale.com/control/controlclient"
 	"tailscale.com/types/logger"
 )
@@ -118,7 +118,7 @@ func (h *Handle) EngineStatus() EngineStatus {
 	return h.engineStatusCache
 }
 
-func (h *Handle) LocalAddrs() []wgcfg.CIDR {
+func (h *Handle) LocalAddrs() []netaddr.IPPrefix {
 	h.mu.Lock()
 	defer h.mu.Unlock()
 
@@ -126,7 +126,7 @@ func (h *Handle) LocalAddrs() []wgcfg.CIDR {
 	if nm != nil {
 		return nm.Addresses
 	}
-	return []wgcfg.CIDR{}
+	return []netaddr.IPPrefix{}
 }
 
 func (h *Handle) NetMap() *controlclient.NetworkMap {

ipn/ipnserver/conn_linux.go

@@ -0,0 +1,49 @@
+// Copyright (c) 2021 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build linux
+
+package ipnserver
+
+import (
+	"net"
+
+	"golang.org/x/sys/unix"
+	"tailscale.com/types/logger"
+)
+
+func isReadonlyConn(c net.Conn, logf logger.Logf) (ro bool) {
+	ro = true // conservative default for naked returns below
+	uc, ok := c.(*net.UnixConn)
+	if !ok {
+		logf("unexpected connection type %T", c)
+		return
+	}
+	raw, err := uc.SyscallConn()
+	if err != nil {
+		logf("SyscallConn: %v", err)
+		return
+	}
+
+	var cred *unix.Ucred
+	cerr := raw.Control(func(fd uintptr) {
+		cred, err = unix.GetsockoptUcred(int(fd),
+			unix.SOL_SOCKET,
+			unix.SO_PEERCRED)
+	})
+	if cerr != nil {
+		logf("raw.Control: %v", err)
+		return
+	}
+	if err != nil {
+		logf("raw.Control: %v", err)
+		return
+	}
+	if cred.Uid == 0 {
+		// root is not read-only.
+		return false
+	}
+	logf("non-root connection from %v (read-only)", cred.Uid)
+	return true
+}

ipn/ipnserver/conn_no_ucred.go

@@ -0,0 +1,27 @@
+// Copyright (c) 2021 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !linux
+
+package ipnserver
+
+import (
+	"net"
+
+	"tailscale.com/types/logger"
+)
+
+func isReadonlyConn(c net.Conn, logf logger.Logf) bool {
+	// Windows doesn't need/use this mechanism, at least yet. It
+	// has a different last-user-wins auth model.
+
+	// And on Darwin, we're not using it yet, as the Darwin
+	// tailscaled port isn't yet done, and unix.Ucred and
+	// unix.GetsockoptUcred aren't in x/sys/unix.
+
+	// TODO(bradfitz): OpenBSD and FreeBSD should implement this too.
+	// But their x/sys/unix package is different than Linux, so
+	// I didn't include it for now.
+	return false
+}

ipn/ipnserver/server.go

@@ -34,6 +34,7 @@ import (
 	"tailscale.com/smallzstd"
 	"tailscale.com/types/logger"
 	"tailscale.com/util/pidowner"
+	"tailscale.com/util/systemd"
 	"tailscale.com/version"
 	"tailscale.com/wgengine"
 )
@@ -265,18 +266,24 @@ func (s *server) serveConn(ctx context.Context, c net.Conn, logf logger.Logf) {
 	}
 
 	defer s.removeAndCloseConn(c)
-	logf("incoming control connection")
+	logf("[v1] incoming control connection")
+
+	if isReadonlyConn(c, logf) {
+		ctx = ipn.ReadonlyContextOf(ctx)
+	}
 
 	for ctx.Err() == nil {
 		msg, err := ipn.ReadMsg(br)
 		if err != nil {
-			if ctx.Err() == nil {
+			if errors.Is(err, io.EOF) {
+				logf("[v1] ReadMsg: %v", err)
+			} else if ctx.Err() == nil {
 				logf("ReadMsg: %v", err)
 			}
 			return
 		}
 		s.bsMu.Lock()
-		if err := s.bs.GotCommandMsg(msg); err != nil {
+		if err := s.bs.GotCommandMsg(ctx, msg); err != nil {
 			logf("GotCommandMsg: %v", err)
 		}
 		gotQuit := s.bs.GotQuit
@@ -352,7 +359,7 @@ func (s *server) addConn(c net.Conn, isHTTP bool) (ci connIdentity, err error) {
 		if doReset {
 			s.logf("identity changed; resetting server")
 			s.bsMu.Lock()
-			s.bs.Reset()
+			s.bs.Reset(context.TODO())
 			s.bsMu.Unlock()
 		}
 	}()
@@ -404,7 +411,7 @@ func (s *server) removeAndCloseConn(c net.Conn) {
 		} else {
 			s.logf("client disconnected; stopping server")
 			s.bsMu.Lock()
-			s.bs.Reset()
+			s.bs.Reset(context.TODO())
 			s.bsMu.Unlock()
 		}
 	}
@@ -578,7 +585,7 @@ func Run(ctx context.Context, logf logger.Logf, logid string, getEngine func() (
 	server.bs = ipn.NewBackendServer(logf, b, server.writeToClients)
 
 	if opts.AutostartStateKey != "" {
-		server.bs.GotCommand(&ipn.Command{
+		server.bs.GotCommand(context.TODO(), &ipn.Command{
 			Version: version.Long,
 			Start: &ipn.StartArgs{
 				Opts: ipn.Options{
@@ -589,6 +596,7 @@ func Run(ctx context.Context, logf logger.Logf, logid string, getEngine func() (
 		})
 	}
 
+	systemd.Ready()
 	for i := 1; ctx.Err() == nil; i++ {
 		var c net.Conn
 		var err error
@@ -724,6 +732,10 @@ func BabysitProc(ctx context.Context, args []string, logf logger.Logf) {
 		// pipe. We'll make a new one when we restart the subproc.
 		wStdin.Close()
 
+		if os.Getenv("TS_DEBUG_RESTART_CRASHED") == "0" {
+			log.Fatalf("Process ended.")
+		}
+
 		if time.Since(startTime) < 60*time.Second {
 			bo.BackOff(ctx, fmt.Errorf("subproc early exit: %v", err))
 		} else {

ipn/ipnserver/server_test.go

@@ -56,7 +56,7 @@ func TestRunMultipleAccepts(t *testing.T) {
 		}
 	}
 
-	eng, err := wgengine.NewFakeUserspaceEngine(logf, 0)
+	eng, err := wgengine.NewFakeUserspaceEngine(logf, 0, nil)
 	if err != nil {
 		t.Fatal(err)
 	}

ipn/ipnstate/ipnstate.go

@@ -25,9 +25,10 @@ import (
 
 // Status represents the entire state of the IPN network.
 type Status struct {
-	BackendState string
-	TailscaleIPs []netaddr.IP // Tailscale IP(s) assigned to this node
-	Self         *PeerStatus
+	BackendState   string
+	TailscaleIPs   []netaddr.IP // Tailscale IP(s) assigned to this node
+	Self           *PeerStatus
+	MagicDNSSuffix string // e.g. "userfoo.tailscale.net" (no surrounding dots)
 
 	Peer map[key.Public]*PeerStatus
 	User map[tailcfg.UserID]tailcfg.UserProfile
@@ -64,6 +65,12 @@ type PeerStatus struct {
 	LastHandshake time.Time // with local wireguard
 	KeepAlive     bool
 
+	// ShareeNode indicates this node exists in the netmap because
+	// it's owned by a shared-to user and that node might connect
+	// to us. These nodes should be hidden by "tailscale status"
+	// etc by default.
+	ShareeNode bool `json:",omitempty"`
+
 	// InNetworkMap means that this peer was seen in our latest network map.
 	// In theory, all of InNetworkMap and InMagicSock and InEngine should all be true.
 	InNetworkMap bool
@@ -97,6 +104,12 @@ func (sb *StatusBuilder) SetBackendState(v string) {
 	sb.st.BackendState = v
 }
 
+func (sb *StatusBuilder) SetMagicDNSSuffix(v string) {
+	sb.mu.Lock()
+	defer sb.mu.Unlock()
+	sb.st.MagicDNSSuffix = v
+}
+
 func (sb *StatusBuilder) Status() *Status {
 	sb.mu.Lock()
 	defer sb.mu.Unlock()
@@ -218,6 +231,9 @@ func (sb *StatusBuilder) AddPeer(peer key.Public, st *PeerStatus) {
 	if st.KeepAlive {
 		e.KeepAlive = true
 	}
+	if st.ShareeNode {
+		e.ShareeNode = true
+	}
 }
 
 type StatusUpdater interface {

ipn/local.go

@@ -29,6 +29,8 @@ import (
 	"tailscale.com/types/empty"
 	"tailscale.com/types/key"
 	"tailscale.com/types/logger"
+	"tailscale.com/types/wgkey"
+	"tailscale.com/util/systemd"
 	"tailscale.com/version"
 	"tailscale.com/wgengine"
 	"tailscale.com/wgengine/filter"
@@ -82,7 +84,7 @@ type LocalBackend struct {
 	userID         string   // current controlling user ID (for Windows, primarily)
 	prefs          *Prefs
 	inServerMode   bool
-	machinePrivKey wgcfg.PrivateKey
+	machinePrivKey wgkey.Private
 	state          State
 	// hostinfo is mutated in-place while mu is held.
 	hostinfo *tailcfg.Hostinfo
@@ -199,6 +201,7 @@ func (b *LocalBackend) UpdateStatus(sb *ipnstate.StatusBuilder) {
 	// TODO: hostinfo, and its networkinfo
 	// TODO: EngineStatus copy (and deprecate it?)
 	if b.netMap != nil {
+		sb.SetMagicDNSSuffix(b.netMap.MagicDNSSuffix())
 		for id, up := range b.netMap.UserProfiles {
 			sb.AddUser(id, up)
 		}
@@ -208,8 +211,14 @@ func (b *LocalBackend) UpdateStatus(sb *ipnstate.StatusBuilder) {
 				lastSeen = *p.LastSeen
 			}
 			var tailAddr string
-			if len(p.Addresses) > 0 {
-				tailAddr = strings.TrimSuffix(p.Addresses[0].String(), "/32")
+			for _, addr := range p.Addresses {
+				// The peer struct currently only allows a single
+				// Tailscale IP address. For compatibility with the
+				// old display, make sure it's the IPv4 address.
+				if addr.IP.Is4() && addr.IsSingleIP() && tsaddr.IsTailscaleIP(addr.IP) {
+					tailAddr = addr.IP.String()
+					break
+				}
 			}
 			sb.AddPeer(key.Public(p.Key), &ipnstate.PeerStatus{
 				InNetworkMap: true,
@@ -221,6 +230,7 @@ func (b *LocalBackend) UpdateStatus(sb *ipnstate.StatusBuilder) {
 				KeepAlive:    p.KeepAlive,
 				Created:      p.Created,
 				LastSeen:     lastSeen,
+				ShareeNode:   p.Hostinfo.ShareeNode,
 			})
 		}
 	}
@@ -243,7 +253,11 @@ func (b *LocalBackend) setClientStatus(st controlclient.Status) {
 	// The following do not depend on any data for which we need to lock b.
 	if st.Err != "" {
 		// TODO(crawshaw): display in the UI.
-		b.logf("Received error: %v", st.Err)
+		if st.Err == "EOF" {
+			b.logf("[v1] Received error: EOF")
+		} else {
+			b.logf("Received error: %v", st.Err)
+		}
 		return
 	}
 	if st.LoginFinished != nil {
@@ -307,7 +321,7 @@ func (b *LocalBackend) setClientStatus(st controlclient.Status) {
 		if netMap != nil {
 			diff := st.NetMap.ConciseDiffFrom(netMap)
 			if strings.TrimSpace(diff) == "" {
-				b.logf("netmap diff: (none)")
+				b.logf("[v1] netmap diff: (none)")
 			} else {
 				b.logf("netmap diff:\n%v", diff)
 			}
@@ -338,7 +352,7 @@ func (b *LocalBackend) setClientStatus(st controlclient.Status) {
 // This updates the endpoints both in the backend and in the control client.
 func (b *LocalBackend) setWgengineStatus(s *wgengine.Status, err error) {
 	if err != nil {
-		b.logf("wgengine status error: %#v", err)
+		b.logf("wgengine status error: %v", err)
 		return
 	}
 	if s == nil {
@@ -522,9 +536,9 @@ func (b *LocalBackend) updateFilter(netMap *controlclient.NetworkMap, prefs *Pre
 	// quite hard to debug, so save yourself the trouble.
 	var (
 		haveNetmap   = netMap != nil
-		addrs        []wgcfg.CIDR
-		packetFilter filter.Matches
-		advRoutes    []wgcfg.CIDR
+		addrs        []netaddr.IPPrefix
+		packetFilter []filter.Match
+		advRoutes    []netaddr.IPPrefix
 		shieldsUp    = prefs == nil || prefs.ShieldsUp // Be conservative when not ready
 	)
 	if haveNetmap {
@@ -546,12 +560,11 @@ func (b *LocalBackend) updateFilter(netMap *controlclient.NetworkMap, prefs *Pre
 		return
 	}
 
-	localNets := wgCIDRsToFilter(netMap.Addresses, advRoutes)
+	localNets := unmapIPPrefixes(netMap.Addresses, advRoutes)
 
 	if shieldsUp {
 		b.logf("netmap packet filter: (shields up)")
-		var prevFilter *filter.Filter // don't reuse old filter state
-		b.e.SetFilter(filter.New(filter.Matches{}, localNets, prevFilter, b.logf))
+		b.e.SetFilter(filter.NewShieldsUpFilter(b.logf))
 	} else {
 		b.logf("netmap packet filter: %v", packetFilter)
 		b.e.SetFilter(filter.New(packetFilter, localNets, b.e.GetFilter(), b.logf))
@@ -560,7 +573,7 @@ func (b *LocalBackend) updateFilter(netMap *controlclient.NetworkMap, prefs *Pre
 
 // dnsCIDRsEqual determines whether two CIDR lists are equal
 // for DNS map construction purposes (that is, only the first entry counts).
-func dnsCIDRsEqual(newAddr, oldAddr []wgcfg.CIDR) bool {
+func dnsCIDRsEqual(newAddr, oldAddr []netaddr.IPPrefix) bool {
 	if len(newAddr) != len(oldAddr) {
 		return false
 	}
@@ -614,11 +627,11 @@ func (b *LocalBackend) updateDNSMap(netMap *controlclient.NetworkMap) {
 	}
 
 	nameToIP := make(map[string]netaddr.IP)
-	set := func(name string, addrs []wgcfg.CIDR) {
+	set := func(name string, addrs []netaddr.IPPrefix) {
 		if len(addrs) == 0 || name == "" {
 			return
 		}
-		nameToIP[name] = netaddr.IPFrom16(addrs[0].IP.Addr)
+		nameToIP[name] = addrs[0].IP
 	}
 
 	for _, peer := range netMap.Peers {
@@ -626,7 +639,7 @@ func (b *LocalBackend) updateDNSMap(netMap *controlclient.NetworkMap) {
 	}
 	set(netMap.Name, netMap.Addresses)
 
-	dnsMap := tsdns.NewMap(nameToIP, domainsForProxying(netMap))
+	dnsMap := tsdns.NewMap(nameToIP, magicDNSRootDomains(netMap))
 	// map diff will be logged in tsdns.Resolver.SetMap.
 	b.e.SetDNSMap(dnsMap)
 }
@@ -725,7 +738,7 @@ func (b *LocalBackend) initMachineKeyLocked() (err error) {
 		return nil
 	}
 
-	var legacyMachineKey wgcfg.PrivateKey
+	var legacyMachineKey wgkey.Private
 	if b.prefs.Persist != nil {
 		legacyMachineKey = b.prefs.Persist.LegacyFrontendPrivateMachineKey
 	}
@@ -760,7 +773,7 @@ func (b *LocalBackend) initMachineKeyLocked() (err error) {
 	} else {
 		b.logf("generating new machine key")
 		var err error
-		b.machinePrivKey, err = wgcfg.NewPrivateKey()
+		b.machinePrivKey, err = wgkey.NewPrivate()
 		if err != nil {
 			return fmt.Errorf("initializing new machine key: %w", err)
 		}
@@ -995,22 +1008,24 @@ func (b *LocalBackend) parseWgStatusLocked(s *wgengine.Status) (ret EngineStatus
 
 	// [GRINDER STATS LINES] - please don't remove (used for log parsing)
 	if peerStats.Len() > 0 {
-		b.keyLogf("peer keys: %s", strings.TrimSpace(peerKeys.String()))
-		b.statsLogf("v%v peers: %v", version.Long, strings.TrimSpace(peerStats.String()))
+		b.keyLogf("[v1] peer keys: %s", strings.TrimSpace(peerKeys.String()))
+		b.statsLogf("[v1] v%v peers: %v", version.Long, strings.TrimSpace(peerStats.String()))
 	}
 	return ret
 }
 
-// shieldsAreUp returns whether user preferences currently request
-// "shields up" mode, which disallows all inbound connections.
-func (b *LocalBackend) shieldsAreUp() bool {
+// shouldUploadServices reports whether this node should include services
+// in Hostinfo. When the user preferences currently request "shields up"
+// mode, all inbound connections are refused, so services are not reported.
+// Otherwise, shouldUploadServices respects NetMap.CollectServices.
+func (b *LocalBackend) shouldUploadServices() bool {
 	b.mu.Lock()
 	defer b.mu.Unlock()
 
-	if b.prefs == nil {
-		return true // default to safest setting
+	if b.prefs == nil || b.netMap == nil {
+		return false // default to safest setting
 	}
-	return b.prefs.ShieldsUp
+	return !b.prefs.ShieldsUp && b.netMap.CollectServices
 }
 
 func (b *LocalBackend) SetCurrentUserID(uid string) {
@@ -1052,7 +1067,7 @@ func (b *LocalBackend) SetPrefs(newp *Prefs) {
 
 	oldHi := b.hostinfo
 	newHi := oldHi.Clone()
-	newHi.RoutableIPs = append([]wgcfg.CIDR(nil), b.prefs.AdvertiseRoutes...)
+	newHi.RoutableIPs = append([]netaddr.IPPrefix(nil), b.prefs.AdvertiseRoutes...)
 	applyPrefsToHostinfo(newHi, newp)
 	b.hostinfo = newHi
 	hostInfoChanged := !oldHi.Equal(newHi)
@@ -1110,9 +1125,7 @@ func (b *LocalBackend) SetPrefs(newp *Prefs) {
 // painstakingly constructing it in twelvety other places.
 func (b *LocalBackend) doSetHostinfoFilterServices(hi *tailcfg.Hostinfo) {
 	hi2 := *hi
-	if b.shieldsAreUp() {
-		// No local services are available, since ShieldsUp will block
-		// them all.
+	if !b.shouldUploadServices() {
 		hi2.Services = []tailcfg.Service{}
 	}
 
@@ -1196,20 +1209,14 @@ func (b *LocalBackend) authReconfig() {
 
 	// If CorpDNS is false, rcfg.DNS remains the zero value.
 	if uc.CorpDNS {
-		domains := nm.DNS.Domains
 		proxied := nm.DNS.Proxied
-		if proxied {
-			if len(nm.DNS.Nameservers) == 0 {
-				b.logf("[unexpected] dns proxied but no nameservers")
-				proxied = false
-			} else {
-				// Domains for proxying should come first to avoid leaking queries.
-				domains = append(domainsForProxying(nm), domains...)
-			}
+		if proxied && len(nm.DNS.Nameservers) == 0 {
+			b.logf("[unexpected] dns proxied but no nameservers")
+			proxied = false
 		}
 		rcfg.DNS = dns.Config{
 			Nameservers: nm.DNS.Nameservers,
-			Domains:     domains,
+			Domains:     nm.DNS.Domains,
 			PerDomain:   nm.DNS.PerDomain,
 			Proxied:     proxied,
 		}
@@ -1219,56 +1226,29 @@ func (b *LocalBackend) authReconfig() {
 	if err == wgengine.ErrNoChanges {
 		return
 	}
-	b.logf("authReconfig: ra=%v dns=%v 0x%02x: %v", uc.RouteAll, uc.CorpDNS, flags, err)
+	b.logf("[v1] authReconfig: ra=%v dns=%v 0x%02x: %v", uc.RouteAll, uc.CorpDNS, flags, err)
 }
 
-// domainsForProxying produces a list of search domains for proxied DNS.
-func domainsForProxying(nm *controlclient.NetworkMap) []string {
-	var domains []string
-	if idx := strings.IndexByte(nm.Name, '.'); idx != -1 {
-		domains = append(domains, nm.Name[idx+1:])
+// magicDNSRootDomains returns the subset of nm.DNS.Domains that are the search domains for MagicDNS.
+// Each entry has a trailing period.
+func magicDNSRootDomains(nm *controlclient.NetworkMap) []string {
+	if v := nm.MagicDNSSuffix(); v != "" {
+		return []string{strings.Trim(v, ".") + "."}
 	}
-	for _, peer := range nm.Peers {
-		idx := strings.IndexByte(peer.Name, '.')
-		if idx == -1 {
-			continue
-		}
-		domain := peer.Name[idx+1:]
-		seen := false
-		// In theory this makes the function O(n^2) worst case,
-		// but in practice we expect domains to contain very few elements
-		// (only one until invitations are introduced).
-		for _, seenDomain := range domains {
-			if domain == seenDomain {
-				seen = true
-			}
-		}
-		if !seen {
-			domains = append(domains, domain)
-		}
-	}
-	return domains
+	return nil
 }
 
 // routerConfig produces a router.Config from a wireguard config and IPN prefs.
 func routerConfig(cfg *wgcfg.Config, prefs *Prefs) *router.Config {
-	var addrs []wgcfg.CIDR
-	for _, addr := range cfg.Addresses {
-		addrs = append(addrs, wgcfg.CIDR{
-			IP:   addr.IP,
-			Mask: 32,
-		})
-	}
-
 	rs := &router.Config{
-		LocalAddrs:       wgCIDRToNetaddr(addrs),
-		SubnetRoutes:     wgCIDRToNetaddr(prefs.AdvertiseRoutes),
+		LocalAddrs:       unmapIPPrefixes(cfg.Addresses),
+		SubnetRoutes:     unmapIPPrefixes(prefs.AdvertiseRoutes),
 		SNATSubnetRoutes: !prefs.NoSNAT,
 		NetfilterMode:    prefs.NetfilterMode,
 	}
 
 	for _, peer := range cfg.Peers {
-		rs.Routes = append(rs.Routes, wgCIDRToNetaddr(peer.AllowedIPs)...)
+		rs.Routes = append(rs.Routes, unmapIPPrefixes(peer.AllowedIPs)...)
 	}
 
 	rs.Routes = append(rs.Routes, netaddr.IPPrefix{
@@ -1279,35 +1259,15 @@ func routerConfig(cfg *wgcfg.Config, prefs *Prefs) *router.Config {
 	return rs
 }
 
-// wgCIDRsToFilter converts lists of wgcfg.CIDR into a single list of
-// filter.Net.
-func wgCIDRsToFilter(cidrLists ...[]wgcfg.CIDR) (ret []filter.Net) {
-	for _, cidrs := range cidrLists {
-		for _, cidr := range cidrs {
-			if !cidr.IP.Is4() {
-				continue
-			}
-			ret = append(ret, filter.Net{
-				IP:   filter.NewIP(cidr.IP.IP()),
-				Mask: filter.Netmask(int(cidr.Mask)),
-			})
+func unmapIPPrefixes(ippsList ...[]netaddr.IPPrefix) (ret []netaddr.IPPrefix) {
+	for _, ipps := range ippsList {
+		for _, ipp := range ipps {
+			ret = append(ret, netaddr.IPPrefix{IP: ipp.IP.Unmap(), Bits: ipp.Bits})
 		}
 	}
 	return ret
 }
 
-func wgCIDRToNetaddr(cidrs []wgcfg.CIDR) (ret []netaddr.IPPrefix) {
-	for _, cidr := range cidrs {
-		ncidr, ok := netaddr.FromStdIPNet(cidr.IPNet())
-		if !ok {
-			panic(fmt.Sprintf("conversion of %s from wgcfg to netaddr IPNet failed", cidr))
-		}
-		ncidr.IP = ncidr.IP.Unmap()
-		ret = append(ret, ncidr)
-	}
-	return ret
-}
-
 func applyPrefsToHostinfo(hi *tailcfg.Hostinfo, prefs *Prefs) {
 	if h := prefs.Hostname; h != "" {
 		hi.Hostname = h
@@ -1318,6 +1278,7 @@ func applyPrefsToHostinfo(hi *tailcfg.Hostinfo, prefs *Prefs) {
 	if m := prefs.DeviceModel; m != "" {
 		hi.DeviceModel = m
 	}
+	hi.ShieldsUp = prefs.ShieldsUp
 }
 
 // enterState transitions the backend into newState, updating internal
@@ -1335,6 +1296,8 @@ func (b *LocalBackend) enterState(newState State) {
 	notify := b.notify
 	bc := b.c
 	networkUp := b.prevIfState.AnyInterfaceUp()
+	activeLogin := b.activeLogin
+	authURL := b.authURL
 	b.mu.Unlock()
 
 	if state == newState {
@@ -1352,6 +1315,7 @@ func (b *LocalBackend) enterState(newState State) {
 
 	switch newState {
 	case NeedsLogin:
+		systemd.Status("Needs login: %s", authURL)
 		b.blockEngineUpdates(true)
 		fallthrough
 	case Stopped:
@@ -1359,12 +1323,20 @@ func (b *LocalBackend) enterState(newState State) {
 		if err != nil {
 			b.logf("Reconfig(down): %v", err)
 		}
+
+		if authURL == "" {
+			systemd.Status("Stopped; run 'tailscale up' to log in")
+		}
 	case Starting, NeedsMachineAuth:
 		b.authReconfig()
 		// Needed so that UpdateEndpoints can run
 		b.e.RequestStatus()
 	case Running:
-		break
+		var addrs []string
+		for _, addr := range b.netMap.Addresses {
+			addrs = append(addrs, addr.IP.String())
+		}
+		systemd.Status("Connected; %s; %s", activeLogin, strings.Join(addrs, " "))
 	default:
 		b.logf("[unexpected] unknown newState %#v", newState)
 	}
@@ -1563,8 +1535,8 @@ func (b *LocalBackend) TestOnlyPublicKeys() (machineKey tailcfg.MachineKey, node
 // 1.0.x.  But eventually we want to stop sending the machine key to
 // clients. We can't do that until 1.0.x is no longer supported.
 func temporarilySetMachineKeyInPersist() bool {
-	//lint:ignore S1008 for comments
-	if runtime.GOOS == "darwin" || runtime.GOOS == "android" {
+	switch runtime.GOOS {
+	case "darwin", "ios", "android":
 		// iOS, macOS, Android users can't downgrade anyway.
 		return false
 	}

ipn/local_test.go

@@ -0,0 +1,119 @@
+// Copyright (c) 2021 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ipn
+
+import (
+	"inet.af/netaddr"
+	"tailscale.com/control/controlclient"
+	"tailscale.com/tailcfg"
+	"testing"
+)
+
+func TestNetworkMapCompare(t *testing.T) {
+	prefix1, err := netaddr.ParseIPPrefix("192.168.0.0/24")
+	if err != nil {
+		t.Fatal(err)
+	}
+	node1 := &tailcfg.Node{Addresses: []netaddr.IPPrefix{prefix1}}
+
+	prefix2, err := netaddr.ParseIPPrefix("10.0.0.0/8")
+	if err != nil {
+		t.Fatal(err)
+	}
+	node2 := &tailcfg.Node{Addresses: []netaddr.IPPrefix{prefix2}}
+
+	tests := []struct {
+		name string
+		a, b *controlclient.NetworkMap
+		want bool
+	}{
+		{
+			"both nil",
+			nil,
+			nil,
+			true,
+		},
+		{
+			"b nil",
+			&controlclient.NetworkMap{},
+			nil,
+			false,
+		},
+		{
+			"a nil",
+			nil,
+			&controlclient.NetworkMap{},
+			false,
+		},
+		{
+			"both default",
+			&controlclient.NetworkMap{},
+			&controlclient.NetworkMap{},
+			true,
+		},
+		{
+			"names identical",
+			&controlclient.NetworkMap{Name: "map1"},
+			&controlclient.NetworkMap{Name: "map1"},
+			true,
+		},
+		{
+			"names differ",
+			&controlclient.NetworkMap{Name: "map1"},
+			&controlclient.NetworkMap{Name: "map2"},
+			false,
+		},
+		{
+			"Peers identical",
+			&controlclient.NetworkMap{Peers: []*tailcfg.Node{}},
+			&controlclient.NetworkMap{Peers: []*tailcfg.Node{}},
+			true,
+		},
+		{
+			"Peer list length",
+			// length of Peers list differs
+			&controlclient.NetworkMap{Peers: []*tailcfg.Node{{}}},
+			&controlclient.NetworkMap{Peers: []*tailcfg.Node{}},
+			false,
+		},
+		{
+			"Node names identical",
+			&controlclient.NetworkMap{Peers: []*tailcfg.Node{&tailcfg.Node{Name: "A"}}},
+			&controlclient.NetworkMap{Peers: []*tailcfg.Node{&tailcfg.Node{Name: "A"}}},
+			true,
+		},
+		{
+			"Node names differ",
+			&controlclient.NetworkMap{Peers: []*tailcfg.Node{&tailcfg.Node{Name: "A"}}},
+			&controlclient.NetworkMap{Peers: []*tailcfg.Node{&tailcfg.Node{Name: "B"}}},
+			false,
+		},
+		{
+			"Node lists identical",
+			&controlclient.NetworkMap{Peers: []*tailcfg.Node{node1, node1}},
+			&controlclient.NetworkMap{Peers: []*tailcfg.Node{node1, node1}},
+			true,
+		},
+		{
+			"Node lists differ",
+			&controlclient.NetworkMap{Peers: []*tailcfg.Node{node1, node1}},
+			&controlclient.NetworkMap{Peers: []*tailcfg.Node{node1, node2}},
+			false,
+		},
+		{
+			"Node Users differ",
+			// User field is not checked.
+			&controlclient.NetworkMap{Peers: []*tailcfg.Node{&tailcfg.Node{User: 0}}},
+			&controlclient.NetworkMap{Peers: []*tailcfg.Node{&tailcfg.Node{User: 1}}},
+			true,
+		},
+	}
+	for _, tt := range tests {
+		got := dnsMapsEqual(tt.a, tt.b)
+		if got != tt.want {
+			t.Errorf("%s: Equal = %v; want %v", tt.name, got, tt.want)
+		}
+	}
+}

ipn/loglines_test.go

@@ -23,9 +23,10 @@ import (
 func TestLocalLogLines(t *testing.T) {
 	logListen := tstest.NewLogLineTracker(t.Logf, []string{
 		"SetPrefs: %v",
-		"peer keys: %s",
-		"v%v peers: %v",
+		"[v1] peer keys: %s",
+		"[v1] v%v peers: %v",
 	})
+	defer logListen.Close()
 
 	logid := func(hex byte) logtail.PublicID {
 		var ret logtail.PublicID
@@ -40,7 +41,7 @@ func TestLocalLogLines(t *testing.T) {
 	store := &MemoryStore{
 		cache: make(map[StateKey][]byte),
 	}
-	e, err := wgengine.NewFakeUserspaceEngine(logListen.Logf, 0)
+	e, err := wgengine.NewFakeUserspaceEngine(logListen.Logf, 0, nil)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -71,7 +72,7 @@ func TestLocalLogLines(t *testing.T) {
 	prefs.Persist = persist
 	lb.SetPrefs(prefs)
 
-	t.Run("after_prefs", testWantRemain("peer keys: %s", "v%v peers: %v"))
+	t.Run("after_prefs", testWantRemain("[v1] peer keys: %s", "[v1] v%v peers: %v"))
 
 	// log peers, peer keys
 	status := &wgengine.Status{

ipn/message.go

@@ -6,6 +6,7 @@ package ipn
 
 import (
 	"bytes"
+	"context"
 	"encoding/binary"
 	"encoding/json"
 	"errors"
@@ -20,6 +21,24 @@ import (
 	"tailscale.com/version"
 )
 
+type readOnlyContextKey struct{}
+
+// IsReadonlyContext reports whether ctx is a read-only context, as currently used
+// by Unix non-root users running the "tailscale" CLI command. They can run "status",
+// but not much else.
+func IsReadonlyContext(ctx context.Context) bool {
+	return ctx.Value(readOnlyContextKey{}) != nil
+}
+
+// ReadonlyContextOf returns ctx wrapped with a context value that
+// will make IsReadonlyContext reports true.
+func ReadonlyContextOf(ctx context.Context) context.Context {
+	if IsReadonlyContext(ctx) {
+		return ctx
+	}
+	return context.WithValue(ctx, readOnlyContextKey{}, readOnlyContextKey{})
+}
+
 var jsonEscapedZero = []byte(`\u0000`)
 
 type NoArgs struct{}
@@ -111,7 +130,7 @@ func (bs *BackendServer) SendInUseOtherUserErrorMessage(msg string) {
 
 // GotCommandMsg parses the incoming message b as a JSON Command and
 // calls GotCommand with it.
-func (bs *BackendServer) GotCommandMsg(b []byte) error {
+func (bs *BackendServer) GotCommandMsg(ctx context.Context, b []byte) error {
 	cmd := &Command{}
 	if len(b) == 0 {
 		return nil
@@ -119,15 +138,15 @@ func (bs *BackendServer) GotCommandMsg(b []byte) error {
 	if err := json.Unmarshal(b, cmd); err != nil {
 		return err
 	}
-	return bs.GotCommand(cmd)
+	return bs.GotCommand(ctx, cmd)
 }
 
-func (bs *BackendServer) GotFakeCommand(cmd *Command) error {
+func (bs *BackendServer) GotFakeCommand(ctx context.Context, cmd *Command) error {
 	cmd.Version = version.Long
-	return bs.GotCommand(cmd)
+	return bs.GotCommand(ctx, cmd)
 }
 
-func (bs *BackendServer) GotCommand(cmd *Command) error {
+func (bs *BackendServer) GotCommand(ctx context.Context, cmd *Command) error {
 	if cmd.Version != version.Long && !cmd.AllowVersionSkew {
 		vs := fmt.Sprintf("GotCommand: Version mismatch! frontend=%#v backend=%#v",
 			cmd.Version, version.Long)
@@ -141,12 +160,33 @@ func (bs *BackendServer) GotCommand(cmd *Command) error {
 		})
 		return nil
 	}
+
+	// TODO(bradfitz): finish plumbing context down to all the methods below;
+	// currently we just check for read-only contexts in this method and
+	// then never use contexts again.
+
+	// Actions permitted with a read-only context:
+	if c := cmd.RequestEngineStatus; c != nil {
+		bs.b.RequestEngineStatus()
+		return nil
+	} else if c := cmd.RequestStatus; c != nil {
+		bs.b.RequestStatus()
+		return nil
+	} else if c := cmd.Ping; c != nil {
+		bs.b.Ping(c.IP)
+		return nil
+	}
+
+	if IsReadonlyContext(ctx) {
+		msg := "permission denied"
+		bs.send(Notify{ErrMessage: &msg})
+		return nil
+	}
+
 	if cmd.Quit != nil {
 		bs.GotQuit = true
 		return errors.New("Quit command received")
-	}
-
-	if c := cmd.Start; c != nil {
+	} else if c := cmd.Start; c != nil {
 		opts := c.Opts
 		opts.Notify = bs.send
 		return bs.b.Start(opts)
@@ -165,27 +205,17 @@ func (bs *BackendServer) GotCommand(cmd *Command) error {
 	} else if c := cmd.SetWantRunning; c != nil {
 		bs.b.SetWantRunning(*c)
 		return nil
-	} else if c := cmd.RequestEngineStatus; c != nil {
-		bs.b.RequestEngineStatus()
-		return nil
-	} else if c := cmd.RequestStatus; c != nil {
-		bs.b.RequestStatus()
-		return nil
 	} else if c := cmd.FakeExpireAfter; c != nil {
 		bs.b.FakeExpireAfter(c.Duration)
 		return nil
-	} else if c := cmd.Ping; c != nil {
-		bs.b.Ping(c.IP)
-		return nil
-	} else {
-		return fmt.Errorf("BackendServer.Do: no command specified")
 	}
+	return fmt.Errorf("BackendServer.Do: no command specified")
 }
 
-func (bs *BackendServer) Reset() error {
+func (bs *BackendServer) Reset(ctx context.Context) error {
 	// Tell the backend we got a Logout command, which will cause it
 	// to forget all its authentication information.
-	return bs.GotFakeCommand(&Command{Logout: &NoArgs{}})
+	return bs.GotFakeCommand(ctx, &Command{Logout: &NoArgs{}})
 }
 
 type BackendClient struct {

ipn/message_test.go

@@ -6,6 +6,7 @@ package ipn
 
 import (
 	"bytes"
+	"context"
 	"testing"
 	"time"
 
@@ -81,7 +82,7 @@ func TestClientServer(t *testing.T) {
 		serverToClientCh <- append([]byte{}, b...)
 	}
 	clientToServer := func(b []byte) {
-		bs.GotCommandMsg(b)
+		bs.GotCommandMsg(context.TODO(), b)
 	}
 	slogf := func(fmt string, args ...interface{}) {
 		t.Logf("s: "+fmt, args...)

ipn/prefs.go

@@ -5,6 +5,7 @@
 package ipn
 
 import (
+	"bytes"
 	"encoding/json"
 	"fmt"
 	"io/ioutil"
@@ -14,7 +15,7 @@ import (
 	"runtime"
 	"strings"
 
-	"github.com/tailscale/wireguard-go/wgcfg"
+	"inet.af/netaddr"
 	"tailscale.com/atomicfile"
 	"tailscale.com/control/controlclient"
 	"tailscale.com/wgengine/router"
@@ -54,7 +55,7 @@ type Prefs struct {
 	// ShieldsUp indicates whether to block all incoming connections,
 	// regardless of the control-provided packet filter. If false, we
 	// use the packet filter as provided. If true, we block incoming
-	// connections.
+	// connections. This overrides tailcfg.Hostinfo's ShieldsUp.
 	ShieldsUp bool
 
 	// AdvertiseTags specifies groups that this node wants to join, for
@@ -99,7 +100,7 @@ type Prefs struct {
 	// AdvertiseRoutes specifies CIDR prefixes to advertise into the
 	// Tailscale network as reachable through the current
 	// node.
-	AdvertiseRoutes []wgcfg.CIDR
+	AdvertiseRoutes []netaddr.IPPrefix
 
 	// NoSNAT specifies whether to source NAT traffic going to
 	// destinations in AdvertiseRoutes. The default is to apply source
@@ -205,12 +206,12 @@ func (p *Prefs) Equals(p2 *Prefs) bool {
 		p.Persist.Equals(p2.Persist)
 }
 
-func compareIPNets(a, b []wgcfg.CIDR) bool {
+func compareIPNets(a, b []netaddr.IPPrefix) bool {
 	if len(a) != len(b) {
 		return false
 	}
 	for i := range a {
-		if !a[i].IP.Equal(b[i].IP) || a[i].Mask != b[i].Mask {
+		if a[i] != b[i] {
 			return false
 		}
 	}
@@ -276,6 +277,14 @@ func LoadPrefs(filename string) (*Prefs, error) {
 	if err != nil {
 		return nil, fmt.Errorf("LoadPrefs open: %w", err) // err includes path
 	}
+	if bytes.Contains(data, jsonEscapedZero) {
+		// Tailscale 1.2.0 - 1.2.8 on Windows had a memory corruption bug
+		// in the backend process that ended up sending NULL bytes over JSON
+		// to the frontend which wrote them out to JSON files on disk.
+		// So if we see one, treat is as corrupt and the user will need
+		// to log in again. (better than crashing)
+		return nil, os.ErrNotExist
+	}
 	p, err := PrefsFromBytes(data, false)
 	if err != nil {
 		return nil, fmt.Errorf("LoadPrefs(%q) decode: %w", filename, err)
@@ -287,7 +296,7 @@ func SavePrefs(filename string, p *Prefs) {
 	log.Printf("Saving prefs %v %v\n", filename, p.Pretty())
 	data := p.ToBytes()
 	os.MkdirAll(filepath.Dir(filename), 0700)
-	if err := atomicfile.WriteFile(filename, data, 0666); err != nil {
+	if err := atomicfile.WriteFile(filename, data, 0600); err != nil {
 		log.Printf("SavePrefs: %v\n", err)
 	}
 }

ipn/prefs_clone.go

@@ -7,7 +7,7 @@
 package ipn
 
 import (
-	"github.com/tailscale/wireguard-go/wgcfg"
+	"inet.af/netaddr"
 	"tailscale.com/control/controlclient"
 	"tailscale.com/wgengine/router"
 )
@@ -44,7 +44,7 @@ var _PrefsNeedsRegeneration = Prefs(struct {
 	DeviceModel      string
 	NotepadURLs      bool
 	ForceDaemon      bool
-	AdvertiseRoutes  []wgcfg.CIDR
+	AdvertiseRoutes  []netaddr.IPPrefix
 	NoSNAT           bool
 	NetfilterMode    router.NetfilterMode
 	Persist          *controlclient.Persist

ipn/prefs_test.go

@@ -7,14 +7,16 @@ package ipn
 import (
 	"errors"
 	"fmt"
+	"io/ioutil"
 	"os"
 	"reflect"
 	"testing"
 	"time"
 
-	"github.com/tailscale/wireguard-go/wgcfg"
+	"inet.af/netaddr"
 	"tailscale.com/control/controlclient"
 	"tailscale.com/tstest"
+	"tailscale.com/types/wgkey"
 	"tailscale.com/wgengine/router"
 )
 
@@ -34,9 +36,9 @@ func TestPrefsEqual(t *testing.T) {
 			have, prefsHandles)
 	}
 
-	nets := func(strs ...string) (ns []wgcfg.CIDR) {
+	nets := func(strs ...string) (ns []netaddr.IPPrefix) {
 		for _, s := range strs {
-			n, err := wgcfg.ParseCIDR(s)
+			n, err := netaddr.ParseIPPrefix(s)
 			if err != nil {
 				panic(err)
 			}
@@ -165,12 +167,12 @@ func TestPrefsEqual(t *testing.T) {
 
 		{
 			&Prefs{AdvertiseRoutes: nil},
-			&Prefs{AdvertiseRoutes: []wgcfg.CIDR{}},
+			&Prefs{AdvertiseRoutes: []netaddr.IPPrefix{}},
 			true,
 		},
 		{
-			&Prefs{AdvertiseRoutes: []wgcfg.CIDR{}},
-			&Prefs{AdvertiseRoutes: []wgcfg.CIDR{}},
+			&Prefs{AdvertiseRoutes: []netaddr.IPPrefix{}},
+			&Prefs{AdvertiseRoutes: []netaddr.IPPrefix{}},
 			true,
 		},
 		{
@@ -346,7 +348,7 @@ func TestPrefsPretty(t *testing.T) {
 		{
 			Prefs{
 				Persist: &controlclient.Persist{
-					PrivateNodeKey: wgcfg.PrivateKey{1: 1},
+					PrivateNodeKey: wgkey.Private{1: 1},
 				},
 			},
 			"linux",
@@ -371,3 +373,25 @@ func TestLoadPrefsNotExist(t *testing.T) {
 	}
 	t.Fatalf("unexpected prefs=%#v, err=%v", p, err)
 }
+
+// TestLoadPrefsFileWithZeroInIt verifies that LoadPrefs hanldes corrupted input files.
+// See issue #954 for details.
+func TestLoadPrefsFileWithZeroInIt(t *testing.T) {
+	f, err := ioutil.TempFile("", "TestLoadPrefsFileWithZeroInIt")
+	if err != nil {
+		t.Fatal(err)
+	}
+	path := f.Name()
+	if _, err := f.Write(jsonEscapedZero); err != nil {
+		t.Fatal(err)
+	}
+	f.Close()
+	defer os.Remove(path)
+
+	p, err := LoadPrefs(path)
+	if errors.Is(err, os.ErrNotExist) {
+		// expected.
+		return
+	}
+	t.Fatalf("unexpected prefs=%#v, err=%v", p, err)
+}

ipn/store.go

@@ -24,7 +24,7 @@ var ErrStateNotExist = errors.New("no state with given ID")
 
 const (
 	// MachineKeyStateKey is the key under which we store the machine key,
-	// in its wgcfg.PrivateKey.MarshalText representation.
+	// in its wgkey.Private.MarshalText representation.
 	MachineKeyStateKey = StateKey("_machinekey")
 
 	// GlobalDaemonStateKey is the ipn.StateKey that tailscaled

logpolicy/logpolicy.go

@@ -25,7 +25,7 @@ import (
 	"strings"
 	"time"
 
-	"golang.org/x/crypto/ssh/terminal"
+	"golang.org/x/term"
 	"tailscale.com/atomicfile"
 	"tailscale.com/logtail"
 	"tailscale.com/logtail/filch"
@@ -35,6 +35,7 @@ import (
 	"tailscale.com/paths"
 	"tailscale.com/smallzstd"
 	"tailscale.com/types/logger"
+	"tailscale.com/util/racebuild"
 	"tailscale.com/version"
 )
 
@@ -48,7 +49,7 @@ type Config struct {
 // Policy is a logger and its public ID.
 type Policy struct {
 	// Logtail is the logger.
-	Logtail logtail.Logger
+	Logtail *logtail.Logger
 	// PublicID is the logger's instance identifier.
 	PublicID logtail.PublicID
 }
@@ -310,7 +311,7 @@ func tryFixLogStateLocation(dir, cmdname string) {
 // given collection name.
 func New(collection string) *Policy {
 	var lflags int
-	if terminal.IsTerminal(2) || runtime.GOOS == "windows" {
+	if term.IsTerminal(2) || runtime.GOOS == "windows" {
 		lflags = 0
 	} else {
 		lflags = log.LstdFlags
@@ -390,13 +391,13 @@ func New(collection string) *Policy {
 	if filchBuf != nil {
 		c.Buffer = filchBuf
 	}
-	lw := logtail.Log(c, log.Printf)
+	lw := logtail.NewLogger(c, log.Printf)
 	log.SetFlags(0) // other logflags are set on console, not here
 	log.SetOutput(lw)
 
 	log.Printf("Program starting: v%v, Go %v: %#v",
 		version.Long,
-		strings.TrimPrefix(runtime.Version(), "go"),
+		goVersion(),
 		os.Args)
 	log.Printf("LogID: %v", newc.PublicID)
 	if filchErr != nil {
@@ -412,6 +413,15 @@ func New(collection string) *Policy {
 	}
 }
 
+// SetVerbosityLevel controls the verbosity level that should be
+// written to stderr. 0 is the default (not verbose). Levels 1 or higher
+// are increasingly verbose.
+//
+// It should not be changed concurrently with log writes.
+func (p *Policy) SetVerbosityLevel(level int) {
+	p.Logtail.SetVerbosityLevel(level)
+}
+
 // Close immediately shuts down the logger.
 func (p *Policy) Close() {
 	ctx, cancel := context.WithCancel(context.Background())
@@ -479,3 +489,11 @@ func newLogtailTransport(host string) *http.Transport {
 
 	return tr
 }
+
+func goVersion() string {
+	v := strings.TrimPrefix(runtime.Version(), "go")
+	if racebuild.On {
+		return v + "-race"
+	}
+	return v
+}

logtail/example/logtail/logtail.go

@@ -31,7 +31,7 @@ func main() {
 		log.Fatalf("logtail: bad -privateid: %v", err)
 	}
 
-	logger := logtail.Log(logtail.Config{
+	logger := logtail.NewLogger(logtail.Config{
 		Collection: *collection,
 		PrivateID:  id,
 	}, log.Printf)

logtail/filch/filch.go

@@ -131,11 +131,11 @@ func New(filePrefix string, opts Options) (f *Filch, err error) {
 	path1 := filePrefix + ".log1.txt"
 	path2 := filePrefix + ".log2.txt"
 
-	f1, err = os.OpenFile(path1, os.O_CREATE|os.O_RDWR, 0666)
+	f1, err = os.OpenFile(path1, os.O_CREATE|os.O_RDWR, 0600)
 	if err != nil {
 		return nil, err
 	}
-	f2, err = os.OpenFile(path2, os.O_CREATE|os.O_RDWR, 0666)
+	f2, err = os.OpenFile(path2, os.O_CREATE|os.O_RDWR, 0600)
 	if err != nil {
 		return nil, err
 	}

logtail/logtail.go

@@ -14,6 +14,7 @@ import (
 	"io/ioutil"
 	"net/http"
 	"os"
+	"strconv"
 	"time"
 
 	"tailscale.com/logtail/backoff"
@@ -24,34 +25,6 @@ import (
 // Config.BaseURL isn't provided.
 const DefaultHost = "log.tailscale.io"
 
-type Logger interface {
-	// Write logs an encoded JSON blob.
-	//
-	// If the []byte passed to Write is not an encoded JSON blob,
-	// then contents is fit into a JSON blob and written.
-	//
-	// This is intended as an interface for the stdlib "log" package.
-	Write([]byte) (int, error)
-
-	// Flush uploads all logs to the server.
-	// It blocks until complete or there is an unrecoverable error.
-	Flush() error
-
-	// Shutdown gracefully shuts down the logger while completing any
-	// remaining uploads.
-	//
-	// It will block, continuing to try and upload unless the passed
-	// context object interrupts it by being done.
-	// If the shutdown is interrupted, an error is returned.
-	Shutdown(context.Context) error
-
-	// Close shuts down this logger object, the background log uploader
-	// process, and any associated goroutines.
-	//
-	// DEPRECATED: use Shutdown
-	Close()
-}
-
 type Encoder interface {
 	EncodeAll(src, dst []byte) []byte
 	Close() error
@@ -66,15 +39,16 @@ type Config struct {
 	LowMemory      bool             // if true, logtail minimizes memory use
 	TimeNow        func() time.Time // if set, subsitutes uses of time.Now
 	Stderr         io.Writer        // if set, logs are sent here instead of os.Stderr
+	StderrLevel    int              // max verbosity level to write to stderr; 0 means the non-verbose messages only
 	Buffer         Buffer           // temp storage, if nil a MemoryBuffer
 	NewZstdEncoder func() Encoder   // if set, used to compress logs for transmission
 
-	// DrainLogs, if non-nil, disables autmatic uploading of new logs,
+	// DrainLogs, if non-nil, disables automatic uploading of new logs,
 	// so that logs are only uploaded when a token is sent to DrainLogs.
 	DrainLogs <-chan struct{}
 }
 
-func Log(cfg Config, logf tslogger.Logf) Logger {
+func NewLogger(cfg Config, logf tslogger.Logf) *Logger {
 	if cfg.BaseURL == "" {
 		cfg.BaseURL = "https://" + DefaultHost
 	}
@@ -94,8 +68,9 @@ func Log(cfg Config, logf tslogger.Logf) Logger {
 		}
 		cfg.Buffer = NewMemoryBuffer(pendingSize)
 	}
-	l := &logger{
+	l := &Logger{
 		stderr:         cfg.Stderr,
+		stderrLevel:    cfg.StderrLevel,
 		httpc:          cfg.HTTPC,
 		url:            cfg.BaseURL + "/c/" + cfg.Collection + "/" + cfg.PrivateID.String(),
 		lowMem:         cfg.LowMemory,
@@ -122,8 +97,11 @@ func Log(cfg Config, logf tslogger.Logf) Logger {
 	return l
 }
 
-type logger struct {
+// Logger writes logs, splitting them as configured between local
+// logging facilities and uploading to a log server.
+type Logger struct {
 	stderr         io.Writer
+	stderrLevel    int
 	httpc          *http.Client
 	url            string
 	lowMem         bool
@@ -141,7 +119,22 @@ type logger struct {
 	shutdownDone  chan struct{} // closd when shutdown complete
 }
 
-func (l *logger) Shutdown(ctx context.Context) error {
+// SetVerbosityLevel controls the verbosity level that should be
+// written to stderr. 0 is the default (not verbose). Levels 1 or higher
+// are increasingly verbose.
+//
+// It should not be changed concurrently with log writes.
+func (l *Logger) SetVerbosityLevel(level int) {
+	l.stderrLevel = level
+}
+
+// Shutdown gracefully shuts down the logger while completing any
+// remaining uploads.
+//
+// It will block, continuing to try and upload unless the passed
+// context object interrupts it by being done.
+// If the shutdown is interrupted, an error is returned.
+func (l *Logger) Shutdown(ctx context.Context) error {
 	done := make(chan struct{})
 	go func() {
 		select {
@@ -163,7 +156,11 @@ func (l *logger) Shutdown(ctx context.Context) error {
 	return nil
 }
 
-func (l *logger) Close() {
+// Close shuts down this logger object, the background log uploader
+// process, and any associated goroutines.
+//
+// Deprecated: use Shutdown
+func (l *Logger) Close() {
 	l.Shutdown(context.Background())
 }
 
@@ -174,7 +171,7 @@ func (l *logger) Close() {
 //
 // If the caller provides a DrainLogs channel, then unblock-drain-on-Write
 // is disabled, and it is up to the caller to trigger unblock the drain.
-func (l *logger) drainBlock() (shuttingDown bool) {
+func (l *Logger) drainBlock() (shuttingDown bool) {
 	if l.drainLogs == nil {
 		select {
 		case <-l.shutdownStart:
@@ -193,7 +190,7 @@ func (l *logger) drainBlock() (shuttingDown bool) {
 
 // drainPending drains and encodes a batch of logs from the buffer for upload.
 // If no logs are available, drainPending blocks until logs are available.
-func (l *logger) drainPending() (res []byte) {
+func (l *Logger) drainPending() (res []byte) {
 	buf := new(bytes.Buffer)
 	entries := 0
 
@@ -254,13 +251,22 @@ func (l *logger) drainPending() (res []byte) {
 }
 
 // This is the goroutine that repeatedly uploads logs in the background.
-func (l *logger) uploading(ctx context.Context) {
+func (l *Logger) uploading(ctx context.Context) {
 	defer close(l.shutdownDone)
 
 	for {
 		body := l.drainPending()
-		if l.zstdEncoder != nil {
-			body = l.zstdEncoder.EncodeAll(body, nil)
+		origlen := -1 // sentinel value: uncompressed
+		// Don't attempt to compress tiny bodies; not worth the CPU cycles.
+		if l.zstdEncoder != nil && len(body) > 256 {
+			zbody := l.zstdEncoder.EncodeAll(body, nil)
+			// Only send it compressed if the bandwidth savings are sufficient.
+			// Just the extra headers associated with enabling compression
+			// are 50 bytes by themselves.
+			if len(body)-len(zbody) > 64 {
+				origlen = len(body)
+				body = zbody
+			}
 		}
 
 		for len(body) > 0 {
@@ -269,7 +275,7 @@ func (l *logger) uploading(ctx context.Context) {
 				return
 			default:
 			}
-			uploaded, err := l.upload(ctx, body)
+			uploaded, err := l.upload(ctx, body, origlen)
 			if err != nil {
 				fmt.Fprintf(l.stderr, "logtail: upload: %v\n", err)
 			}
@@ -287,7 +293,10 @@ func (l *logger) uploading(ctx context.Context) {
 	}
 }
 
-func (l *logger) upload(ctx context.Context, body []byte) (uploaded bool, err error) {
+// upload uploads body to the log server.
+// origlen indicates the pre-compression body length.
+// origlen of -1 indicates that the body is not compressed.
+func (l *Logger) upload(ctx context.Context, body []byte, origlen int) (uploaded bool, err error) {
 	req, err := http.NewRequest("POST", l.url, bytes.NewReader(body))
 	if err != nil {
 		// I know of no conditions under which this could fail.
@@ -295,8 +304,9 @@ func (l *logger) upload(ctx context.Context, body []byte) (uploaded bool, err er
 		// TODO record logs to disk
 		panic("logtail: cannot build http request: " + err.Error())
 	}
-	if l.zstdEncoder != nil {
+	if origlen != -1 {
 		req.Header.Add("Content-Encoding", "zstd")
+		req.Header.Add("Orig-Content-Length", strconv.Itoa(origlen))
 	}
 	req.Header["User-Agent"] = nil // not worth writing one; save some bytes
 
@@ -306,7 +316,7 @@ func (l *logger) upload(ctx context.Context, body []byte) (uploaded bool, err er
 	req = req.WithContext(ctx)
 
 	compressedNote := "not-compressed"
-	if l.zstdEncoder != nil {
+	if origlen != -1 {
 		compressedNote = "compressed"
 	}
 
@@ -333,11 +343,13 @@ func (l *logger) upload(ctx context.Context, body []byte) (uploaded bool, err er
 	return true, nil
 }
 
-func (l *logger) Flush() error {
+// Flush uploads all logs to the server.
+// It blocks until complete or there is an unrecoverable error.
+func (l *Logger) Flush() error {
 	return nil
 }
 
-func (l *logger) send(jsonBlob []byte) (int, error) {
+func (l *Logger) send(jsonBlob []byte) (int, error) {
 	n, err := l.buffer.Write(jsonBlob)
 	if l.drainLogs == nil {
 		select {
@@ -350,7 +362,7 @@ func (l *logger) send(jsonBlob []byte) (int, error) {
 
 // TODO: instead of allocating, this should probably just append
 // directly into the output log buffer.
-func (l *logger) encodeText(buf []byte, skipClientTime bool) []byte {
+func (l *Logger) encodeText(buf []byte, skipClientTime bool) []byte {
 	now := l.timeNow()
 
 	// Factor in JSON encoding overhead to try to only do one alloc
@@ -406,7 +418,7 @@ func (l *logger) encodeText(buf []byte, skipClientTime bool) []byte {
 	return b
 }
 
-func (l *logger) encode(buf []byte) []byte {
+func (l *Logger) encode(buf []byte) []byte {
 	if buf[0] != '{' {
 		return l.encodeText(buf, l.skipClientTime) // text fast-path
 	}
@@ -447,11 +459,18 @@ func (l *logger) encode(buf []byte) []byte {
 	return b
 }
 
-func (l *logger) Write(buf []byte) (int, error) {
+// Write logs an encoded JSON blob.
+//
+// If the []byte passed to Write is not an encoded JSON blob,
+// then contents is fit into a JSON blob and written.
+//
+// This is intended as an interface for the stdlib "log" package.
+func (l *Logger) Write(buf []byte) (int, error) {
 	if len(buf) == 0 {
 		return 0, nil
 	}
-	if l.stderr != nil && l.stderr != ioutil.Discard {
+	level, buf := parseAndRemoveLogLevel(buf)
+	if l.stderr != nil && l.stderr != ioutil.Discard && level <= l.stderrLevel {
 		if buf[len(buf)-1] == '\n' {
 			l.stderr.Write(buf)
 		} else {
@@ -465,3 +484,23 @@ func (l *logger) Write(buf []byte) (int, error) {
 	_, err := l.send(b)
 	return len(buf), err
 }
+
+var (
+	openBracketV = []byte("[v")
+	v1           = []byte("[v1] ")
+	v2           = []byte("[v2] ")
+)
+
+// level 0 is normal (or unknown) level; 1+ are increasingly verbose
+func parseAndRemoveLogLevel(buf []byte) (level int, cleanBuf []byte) {
+	if len(buf) == 0 || buf[0] == '{' || !bytes.Contains(buf, openBracketV) {
+		return 0, buf
+	}
+	if bytes.Contains(buf, v1) {
+		return 1, bytes.ReplaceAll(buf, v1, nil)
+	}
+	if bytes.Contains(buf, v2) {
+		return 2, bytes.ReplaceAll(buf, v2, nil)
+	}
+	return 0, buf
+}

logtail/logtail_test.go

@@ -6,6 +6,12 @@ package logtail
 
 import (
 	"context"
+	"encoding/json"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"net/http/httptest"
+	"strings"
 	"testing"
 	"time"
 )
@@ -14,16 +20,215 @@ func TestFastShutdown(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	cancel()
 
-	l := Log(Config{
-		BaseURL: "http://localhost:1234",
+	testServ := httptest.NewServer(http.HandlerFunc(
+		func(w http.ResponseWriter, r *http.Request) {}))
+	defer testServ.Close()
+
+	l := NewLogger(Config{
+		BaseURL: testServ.URL,
 	}, t.Logf)
-	l.Shutdown(ctx)
+	err := l.Shutdown(ctx)
+	if err != nil {
+		t.Error(err)
+	}
+}
+
+// maximum number of times a test will call l.Write()
+const logLines = 3
+
+type LogtailTestServer struct {
+	srv      *httptest.Server // Log server
+	uploaded chan []byte
+}
+
+func NewLogtailTestHarness(t *testing.T) (*LogtailTestServer, *Logger) {
+	ts := LogtailTestServer{}
+
+	// max channel backlog = 1 "started" + #logLines x "log line" + 1 "closed"
+	ts.uploaded = make(chan []byte, 2+logLines)
+
+	ts.srv = httptest.NewServer(http.HandlerFunc(
+		func(w http.ResponseWriter, r *http.Request) {
+			body, err := ioutil.ReadAll(r.Body)
+			if err != nil {
+				t.Error("failed to read HTTP request")
+			}
+			ts.uploaded <- body
+		}))
+
+	t.Cleanup(ts.srv.Close)
+
+	l := NewLogger(Config{BaseURL: ts.srv.URL}, t.Logf)
+
+	// There is always an initial "logtail started" message
+	body := <-ts.uploaded
+	if !strings.Contains(string(body), "started") {
+		t.Errorf("unknown start logging statement: %q", string(body))
+	}
+
+	return &ts, l
+}
+
+func TestDrainPendingMessages(t *testing.T) {
+	ts, l := NewLogtailTestHarness(t)
+
+	for i := 0; i < logLines; i++ {
+		l.Write([]byte("log line"))
+	}
+
+	// all of the "log line" messages usually arrive at once, but poll if needed.
+	body := ""
+	for i := 0; i <= logLines; i++ {
+		body += string(<-ts.uploaded)
+		count := strings.Count(body, "log line")
+		if count == logLines {
+			break
+		}
+		// if we never find count == logLines, the test will eventually time out.
+	}
+
+	err := l.Shutdown(context.Background())
+	if err != nil {
+		t.Error(err)
+	}
+}
+
+func TestEncodeAndUploadMessages(t *testing.T) {
+	ts, l := NewLogtailTestHarness(t)
+
+	tests := []struct {
+		name string
+		log  string
+		want string
+	}{
+		{
+			"plain text",
+			"log line",
+			"log line",
+		},
+		{
+			"simple JSON",
+			`{"text": "log line"}`,
+			"log line",
+		},
+	}
+
+	for _, tt := range tests {
+		io.WriteString(l, tt.log)
+		body := <-ts.uploaded
+
+		data := make(map[string]interface{})
+		err := json.Unmarshal(body, &data)
+		if err != nil {
+			t.Error(err)
+		}
+
+		got := data["text"]
+		if got != tt.want {
+			t.Errorf("%s: got %q; want %q", tt.name, got.(string), tt.want)
+		}
+
+		ltail, ok := data["logtail"]
+		if ok {
+			logtailmap := ltail.(map[string]interface{})
+			_, ok = logtailmap["client_time"]
+			if !ok {
+				t.Errorf("%s: no client_time present", tt.name)
+			}
+		} else {
+			t.Errorf("%s: no logtail map present", tt.name)
+		}
+	}
+
+	err := l.Shutdown(context.Background())
+	if err != nil {
+		t.Error(err)
+	}
+}
+
+func TestEncodeSpecialCases(t *testing.T) {
+	ts, l := NewLogtailTestHarness(t)
+
+	// -------------------------------------------------------------------------
+
+	// JSON log message already contains a logtail field.
+	io.WriteString(l, `{"logtail": "LOGTAIL", "text": "text"}`)
+	body := <-ts.uploaded
+	data := make(map[string]interface{})
+	err := json.Unmarshal(body, &data)
+	if err != nil {
+		t.Error(err)
+	}
+	errorHasLogtail, ok := data["error_has_logtail"]
+	if ok {
+		if errorHasLogtail != "LOGTAIL" {
+			t.Errorf("error_has_logtail: got:%q; want:%q",
+				errorHasLogtail, "LOGTAIL")
+		}
+	} else {
+		t.Errorf("no error_has_logtail field: %v", data)
+	}
+
+	// -------------------------------------------------------------------------
+
+	// special characters
+	io.WriteString(l, "\b\f\n\r\t"+`"\`)
+	bodytext := string(<-ts.uploaded)
+	// json.Unmarshal would unescape the characters, we have to look at the encoded text
+	escaped := strings.Contains(bodytext, `\b\f\n\r\t\"\`)
+	if !escaped {
+		t.Errorf("special characters got %s", bodytext)
+	}
+
+	// -------------------------------------------------------------------------
+
+	// skipClientTime to omit the logtail metadata
+	l.skipClientTime = true
+	io.WriteString(l, "text")
+	body = <-ts.uploaded
+	data = make(map[string]interface{})
+	err = json.Unmarshal(body, &data)
+	if err != nil {
+		t.Error(err)
+	}
+	_, ok = data["logtail"]
+	if ok {
+		t.Errorf("skipClientTime: unexpected logtail map present: %v", data)
+	}
+
+	// -------------------------------------------------------------------------
+
+	// lowMem + long string
+	l.skipClientTime = false
+	l.lowMem = true
+	longStr := strings.Repeat("0", 512)
+	io.WriteString(l, longStr)
+	body = <-ts.uploaded
+	data = make(map[string]interface{})
+	err = json.Unmarshal(body, &data)
+	if err != nil {
+		t.Error(err)
+	}
+	text, ok := data["text"]
+	if !ok {
+		t.Errorf("lowMem: no text %v", data)
+	}
+	if n := len(text.(string)); n > 300 {
+		t.Errorf("lowMem: got %d chars; want <300 chars", n)
+	}
+
+	// -------------------------------------------------------------------------
+
+	err = l.Shutdown(context.Background())
+	if err != nil {
+		t.Error(err)
+	}
 }
 
 var sink []byte
 
 func TestLoggerEncodeTextAllocs(t *testing.T) {
-	lg := &logger{timeNow: time.Now}
+	lg := &Logger{timeNow: time.Now}
 	inBuf := []byte("some text to encode")
 	n := testing.AllocsPerRun(1000, func() {
 		sink = lg.encodeText(inBuf, false)
@@ -34,7 +239,7 @@ func TestLoggerEncodeTextAllocs(t *testing.T) {
 }
 
 func TestLoggerWriteLength(t *testing.T) {
-	lg := &logger{
+	lg := &Logger{
 		timeNow: time.Now,
 		buffer:  NewMemoryBuffer(1024),
 	}
@@ -47,3 +252,54 @@ func TestLoggerWriteLength(t *testing.T) {
 		t.Errorf("logger.Write wrote %d bytes, expected %d", n, len(inBuf))
 	}
 }
+
+func TestParseAndRemoveLogLevel(t *testing.T) {
+	tests := []struct {
+		log       string
+		wantLevel int
+		wantLog   string
+	}{
+		{
+			"no level",
+			0,
+			"no level",
+		},
+		{
+			"[v1] level 1",
+			1,
+			"level 1",
+		},
+		{
+			"level 1 [v1] ",
+			1,
+			"level 1 ",
+		},
+		{
+			"[v2] level 2",
+			2,
+			"level 2",
+		},
+		{
+			"level [v2] 2",
+			2,
+			"level 2",
+		},
+		{
+			"[v3] no level 3",
+			0,
+			"[v3] no level 3",
+		},
+	}
+
+	for _, tt := range tests {
+		gotLevel, gotLog := parseAndRemoveLogLevel([]byte(tt.log))
+		if gotLevel != tt.wantLevel {
+			t.Errorf("parseAndRemoveLogLevel(%q): got:%d; want %d",
+				tt.log, gotLevel, tt.wantLevel)
+		}
+		if string(gotLog) != tt.wantLog {
+			t.Errorf("parseAndRemoveLogLevel(%q): got:%q; want %q",
+				tt.log, gotLog, tt.wantLog)
+		}
+	}
+}

net/dnscache/dnscache.go

@@ -9,8 +9,11 @@ package dnscache
 import (
 	"context"
 	"fmt"
+	"log"
 	"net"
+	"os"
 	"runtime"
+	"strconv"
 	"sync"
 	"time"
 
@@ -25,7 +28,7 @@ func preferGoResolver() bool {
 	// There does not appear to be a local resolver running
 	// on iOS, and NetworkExtension is good at isolating DNS.
 	// So do not use the Go resolver on macOS/iOS.
-	if runtime.GOOS == "darwin" {
+	if runtime.GOOS == "darwin" || runtime.GOOS == "ios" {
 		return false
 	}
 
@@ -42,8 +45,6 @@ func preferGoResolver() bool {
 // Get returns a caching Resolver singleton.
 func Get() *Resolver { return single }
 
-const fixedTTL = 10 * time.Minute
-
 // Resolver is a minimal DNS caching resolver.
 //
 // The TTL is always fixed for now. It's not intended for general use.
@@ -54,6 +55,15 @@ type Resolver struct {
 	// If nil, net.DefaultResolver is used.
 	Forward *net.Resolver
 
+	// TTL is how long to keep entries cached
+	//
+	// If zero, a default (currently 10 minutes) is used.
+	TTL time.Duration
+
+	// UseLastGood controls whether a cached entry older than TTL is used
+	// if a refresh fails.
+	UseLastGood bool
+
 	sf singleflight.Group
 
 	mu      sync.Mutex
@@ -61,7 +71,8 @@ type Resolver struct {
 }
 
 type ipCacheEntry struct {
-	ip      net.IP
+	ip      net.IP // either v4 or v6
+	ip6     net.IP // nil if no v4 or no v6
 	expires time.Time
 }
 
@@ -72,74 +83,160 @@ func (r *Resolver) fwd() *net.Resolver {
 	return net.DefaultResolver
 }
 
-// LookupIP returns the first IPv4 address found, otherwise the first IPv6 address.
-func (r *Resolver) LookupIP(ctx context.Context, host string) (net.IP, error) {
+func (r *Resolver) ttl() time.Duration {
+	if r.TTL > 0 {
+		return r.TTL
+	}
+	return 10 * time.Minute
+}
+
+var debug, _ = strconv.ParseBool(os.Getenv("TS_DEBUG_DNS_CACHE"))
+
+// LookupIP returns the host's primary IP address (either IPv4 or
+// IPv6, but preferring IPv4) and optionally its IPv6 address, if
+// there is both IPv4 and IPv6.
+//
+// If err is nil, ip will be non-nil. The v6 address may be nil even
+// with a nil error.
+func (r *Resolver) LookupIP(ctx context.Context, host string) (ip, v6 net.IP, err error) {
 	if ip := net.ParseIP(host); ip != nil {
 		if ip4 := ip.To4(); ip4 != nil {
-			return ip4, nil
+			return ip4, nil, nil
 		}
-		return ip, nil
+		if debug {
+			log.Printf("dnscache: %q is an IP", host)
+		}
+		return ip, nil, nil
 	}
 
-	if ip, ok := r.lookupIPCache(host); ok {
-		return ip, nil
+	if ip, ip6, ok := r.lookupIPCache(host); ok {
+		if debug {
+			log.Printf("dnscache: %q = %v (cached)", host, ip)
+		}
+		return ip, ip6, nil
 	}
 
+	type ipPair struct {
+		ip, ip6 net.IP
+	}
 	ch := r.sf.DoChan(host, func() (interface{}, error) {
-		ip, err := r.lookupIP(host)
+		ip, ip6, err := r.lookupIP(host)
 		if err != nil {
 			return nil, err
 		}
-		return ip, nil
+		return ipPair{ip, ip6}, nil
 	})
 	select {
 	case res := <-ch:
 		if res.Err != nil {
-			return nil, res.Err
+			if r.UseLastGood {
+				if ip, ip6, ok := r.lookupIPCacheExpired(host); ok {
+					if debug {
+						log.Printf("dnscache: %q using %v after error", host, ip)
+					}
+					return ip, ip6, nil
+				}
+			}
+			if debug {
+				log.Printf("dnscache: error resolving %q: %v", host, res.Err)
+			}
+			return nil, nil, res.Err
 		}
-		return res.Val.(net.IP), nil
+		pair := res.Val.(ipPair)
+		return pair.ip, pair.ip6, nil
 	case <-ctx.Done():
-		return nil, ctx.Err()
+		if debug {
+			log.Printf("dnscache: context done while resolving %q: %v", host, ctx.Err())
+		}
+		return nil, nil, ctx.Err()
 	}
 }
 
-func (r *Resolver) lookupIPCache(host string) (ip net.IP, ok bool) {
+func (r *Resolver) lookupIPCache(host string) (ip, ip6 net.IP, ok bool) {
 	r.mu.Lock()
 	defer r.mu.Unlock()
 	if ent, ok := r.ipCache[host]; ok && ent.expires.After(time.Now()) {
-		return ent.ip, true
+		return ent.ip, ent.ip6, true
 	}
-	return nil, false
+	return nil, nil, false
 }
 
-func (r *Resolver) lookupIP(host string) (net.IP, error) {
-	if ip, ok := r.lookupIPCache(host); ok {
-		return ip, nil
+func (r *Resolver) lookupIPCacheExpired(host string) (ip, ip6 net.IP, ok bool) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	if ent, ok := r.ipCache[host]; ok {
+		return ent.ip, ent.ip6, true
+	}
+	return nil, nil, false
+}
+
+func (r *Resolver) lookupTimeoutForHost(host string) time.Duration {
+	if r.UseLastGood {
+		if _, _, ok := r.lookupIPCacheExpired(host); ok {
+			// If we have some previous good value for this host,
+			// don't give this DNS lookup much time. If we're in a
+			// situation where the user's DNS server is unreachable
+			// (e.g. their corp DNS server is behind a subnet router
+			// that can't come up due to Tailscale needing to
+			// connect to itself), then we want to fail fast and let
+			// our caller (who set UseLastGood) fall back to using
+			// the last-known-good IP address.
+			return 3 * time.Second
+		}
+	}
+	return 10 * time.Second
+}
+
+func (r *Resolver) lookupIP(host string) (ip, ip6 net.IP, err error) {
+	if ip, ip6, ok := r.lookupIPCache(host); ok {
+		if debug {
+			log.Printf("dnscache: %q found in cache as %v", host, ip)
+		}
+		return ip, ip6, nil
 	}
 
-	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	ctx, cancel := context.WithTimeout(context.Background(), r.lookupTimeoutForHost(host))
 	defer cancel()
 	ips, err := r.fwd().LookupIPAddr(ctx, host)
 	if err != nil {
-		return nil, err
+		return nil, nil, err
 	}
 	if len(ips) == 0 {
-		return nil, fmt.Errorf("no IPs for %q found", host)
+		return nil, nil, fmt.Errorf("no IPs for %q found", host)
 	}
 
+	have4 := false
 	for _, ipa := range ips {
 		if ip4 := ipa.IP.To4(); ip4 != nil {
-			return r.addIPCache(host, ip4, fixedTTL), nil
+			if !have4 {
+				ip6 = ip
+				ip = ip4
+				have4 = true
+			}
+		} else {
+			if have4 {
+				ip6 = ipa.IP
+			} else {
+				ip = ipa.IP
+			}
 		}
 	}
-	return r.addIPCache(host, ips[0].IP, fixedTTL), nil
+	r.addIPCache(host, ip, ip6, r.ttl())
+	return ip, ip6, nil
 }
 
-func (r *Resolver) addIPCache(host string, ip net.IP, d time.Duration) net.IP {
+func (r *Resolver) addIPCache(host string, ip, ip6 net.IP, d time.Duration) {
 	if isPrivateIP(ip) {
 		// Don't cache obviously wrong entries from captive portals.
 		// TODO: use DoH or DoT for the forwarding resolver?
-		return ip
+		if debug {
+			log.Printf("dnscache: %q resolved to private IP %v; using but not caching", host, ip)
+		}
+		return
+	}
+
+	if debug {
+		log.Printf("dnscache: %q resolved to IP %v; caching", host, ip)
 	}
 
 	r.mu.Lock()
@@ -147,8 +244,7 @@ func (r *Resolver) addIPCache(host string, ip net.IP, d time.Duration) net.IP {
 	if r.ipCache == nil {
 		r.ipCache = make(map[string]ipCacheEntry)
 	}
-	r.ipCache[host] = ipCacheEntry{ip: ip, expires: time.Now().Add(d)}
-	return ip
+	r.ipCache[host] = ipCacheEntry{ip: ip, ip6: ip6, expires: time.Now().Add(d)}
 }
 
 func mustCIDR(s string) *net.IPNet {
@@ -168,3 +264,39 @@ var (
 	private2 = mustCIDR("172.16.0.0/12")
 	private3 = mustCIDR("192.168.0.0/16")
 )
+
+type DialContextFunc func(ctx context.Context, network, address string) (net.Conn, error)
+
+// Dialer returns a wrapped DialContext func that uses the provided dnsCache.
+func Dialer(fwd DialContextFunc, dnsCache *Resolver) DialContextFunc {
+	return func(ctx context.Context, network, address string) (net.Conn, error) {
+		host, port, err := net.SplitHostPort(address)
+		if err != nil {
+			// Bogus. But just let the real dialer return an error rather than
+			// inventing a similar one.
+			return fwd(ctx, network, address)
+		}
+		ip, ip6, err := dnsCache.LookupIP(ctx, host)
+		if err != nil {
+			return nil, fmt.Errorf("failed to resolve %q: %w", host, err)
+		}
+		dst := net.JoinHostPort(ip.String(), port)
+		if debug {
+			log.Printf("dnscache: dialing %s, %s for %s", network, dst, address)
+		}
+		c, err := fwd(ctx, network, dst)
+		if err == nil || ctx.Err() != nil || ip6 == nil {
+			return c, err
+		}
+		// Fall back to trying IPv6.
+		// TODO(bradfitz): this is a primarily for IPv6-only
+		// hosts; it's not supposed to be a real Happy
+		// Eyeballs implementation. We should use the net
+		// package's implementation of that by plumbing this
+		// dnscache impl into net.Dialer.Resolver.Dial and
+		// unmarshal/marshal DNS queries/responses to the net
+		// package. This works for v6-only hosts for now.
+		dst = net.JoinHostPort(ip6.String(), port)
+		return fwd(ctx, network, dst)
+	}
+}

net/flowtrack/flowtrack.go

@@ -0,0 +1,104 @@
+// Copyright (c) 2021 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+//
+// Original implementation (from same author) from which this was derived was:
+// https://github.com/golang/groupcache/blob/5b532d6fd5efaf7fa130d4e859a2fde0fc3a9e1b/lru/lru.go
+// ... which was Apache licensed:
+// https://github.com/golang/groupcache/blob/master/LICENSE
+
+// Package flowtrack contains types for tracking TCP/UDP flows by 4-tuples.
+package flowtrack
+
+import (
+	"container/list"
+	"fmt"
+
+	"inet.af/netaddr"
+)
+
+// Tuple is a 4-tuple of source and destination IP and port.
+type Tuple struct {
+	Src netaddr.IPPort
+	Dst netaddr.IPPort
+}
+
+func (t Tuple) String() string {
+	return fmt.Sprintf("(%v => %v)", t.Src, t.Dst)
+}
+
+// Cache is an LRU cache keyed by Tuple.
+//
+// The zero value is valid to use.
+//
+// It is not safe for concurrent access.
+type Cache struct {
+	// MaxEntries is the maximum number of cache entries before
+	// an item is evicted. Zero means no limit.
+	MaxEntries int
+
+	ll *list.List
+	m  map[Tuple]*list.Element // of *entry
+}
+
+// entry is the container/list element type.
+type entry struct {
+	key   Tuple
+	value interface{}
+}
+
+// Add adds a value to the cache, set or updating its assoicated
+// value.
+//
+// If MaxEntries is non-zero and the length of the cache is greater
+// after any addition, the least recently used value is evicted.
+func (c *Cache) Add(key Tuple, value interface{}) {
+	if c.m == nil {
+		c.m = make(map[Tuple]*list.Element)
+		c.ll = list.New()
+	}
+	if ee, ok := c.m[key]; ok {
+		c.ll.MoveToFront(ee)
+		ee.Value.(*entry).value = value
+		return
+	}
+	ele := c.ll.PushFront(&entry{key, value})
+	c.m[key] = ele
+	if c.MaxEntries != 0 && c.Len() > c.MaxEntries {
+		c.RemoveOldest()
+	}
+}
+
+// Get looks up a key's value from the cache, also reporting
+// whether it was present.
+func (c *Cache) Get(key Tuple) (value interface{}, ok bool) {
+	if ele, hit := c.m[key]; hit {
+		c.ll.MoveToFront(ele)
+		return ele.Value.(*entry).value, true
+	}
+	return nil, false
+}
+
+// Remove removes the provided key from the cache if it was present.
+func (c *Cache) Remove(key Tuple) {
+	if ele, hit := c.m[key]; hit {
+		c.removeElement(ele)
+	}
+}
+
+// RemoveOldest removes the oldest item from the cache, if any.
+func (c *Cache) RemoveOldest() {
+	if c.ll != nil {
+		if ele := c.ll.Back(); ele != nil {
+			c.removeElement(ele)
+		}
+	}
+}
+
+func (c *Cache) removeElement(e *list.Element) {
+	c.ll.Remove(e)
+	delete(c.m, e.Value.(*entry).key)
+}
+
+// Len returns the number of items in the cache.
+func (c *Cache) Len() int { return len(c.m) }

net/flowtrack/flowtrack_test.go

@@ -0,0 +1,82 @@
+// Copyright (c) 2021 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flowtrack
+
+import (
+	"testing"
+
+	"inet.af/netaddr"
+)
+
+func TestCache(t *testing.T) {
+	c := &Cache{MaxEntries: 2}
+
+	k1 := Tuple{Src: netaddr.MustParseIPPort("1.1.1.1:1"), Dst: netaddr.MustParseIPPort("1.1.1.1:1")}
+	k2 := Tuple{Src: netaddr.MustParseIPPort("1.1.1.1:1"), Dst: netaddr.MustParseIPPort("2.2.2.2:2")}
+	k3 := Tuple{Src: netaddr.MustParseIPPort("1.1.1.1:1"), Dst: netaddr.MustParseIPPort("3.3.3.3:3")}
+	k4 := Tuple{Src: netaddr.MustParseIPPort("1.1.1.1:1"), Dst: netaddr.MustParseIPPort("4.4.4.4:4")}
+
+	wantLen := func(want int) {
+		t.Helper()
+		if got := c.Len(); got != want {
+			t.Fatalf("Len = %d; want %d", got, want)
+		}
+	}
+	wantVal := func(key Tuple, want interface{}) {
+		t.Helper()
+		got, ok := c.Get(key)
+		if !ok {
+			t.Fatalf("Get(%q) failed; want value %v", key, want)
+		}
+		if got != want {
+			t.Fatalf("Get(%q) = %v; want %v", key, got, want)
+		}
+	}
+	wantMissing := func(key Tuple) {
+		t.Helper()
+		if got, ok := c.Get(key); ok {
+			t.Fatalf("Get(%q) = %v; want absent from cache", key, got)
+		}
+	}
+
+	wantLen(0)
+	c.RemoveOldest() // shouldn't panic
+	c.Remove(k4)     // shouldn't panic
+
+	c.Add(k1, 1)
+	wantLen(1)
+	c.Add(k2, 2)
+	wantLen(2)
+	c.Add(k3, 3)
+	wantLen(2) // hit the max
+
+	wantMissing(k1)
+	c.Remove(k1)
+	wantLen(2) // no change; k1 should've been the deleted one per LRU
+
+	wantVal(k3, 3)
+
+	wantVal(k2, 2)
+	c.Remove(k2)
+	wantLen(1)
+	wantMissing(k2)
+
+	c.Add(k3, 30)
+	wantVal(k3, 30)
+	wantLen(1)
+
+	allocs := int(testing.AllocsPerRun(1000, func() {
+		got, ok := c.Get(k3)
+		if !ok {
+			t.Fatal("missing k3")
+		}
+		if got != 30 {
+			t.Fatalf("got = %d; want 30", got)
+		}
+	}))
+	if allocs != 0 {
+		t.Errorf("allocs = %v; want 0", allocs)
+	}
+}

net/interfaces/interfaces.go

@@ -94,11 +94,6 @@ func LocalAddresses() (regular, loopback []string, err error) {
 				if !ok {
 					continue
 				}
-				if ip.Is6() {
-					// TODO(crawshaw): IPv6 support.
-					// Easy to do here, but we need good endpoint ordering logic.
-					continue
-				}
 				// TODO(apenwarr): don't special case cgNAT.
 				// In the general wireguard case, it might
 				// very well be something we can route to

net/interfaces/interfaces_darwin.go

@@ -5,6 +5,7 @@
 package interfaces
 
 import (
+	"errors"
 	"os/exec"
 
 	"go4.org/mem"
@@ -62,8 +63,12 @@ func likelyHomeRouterIPDarwinExec() (ret netaddr.IP, ok bool) {
 		ip, err := netaddr.ParseIP(string(mem.Append(nil, ipm)))
 		if err == nil && isPrivateIP(ip) {
 			ret = ip
+			// We've found what we're looking for.
+			return errStopReadingNetstatTable
 		}
 		return nil
 	})
 	return ret, !ret.IsZero()
 }
+
+var errStopReadingNetstatTable = errors.New("found private gateway")

net/netcheck/netcheck.go

@@ -28,7 +28,6 @@ import (
 	"go4.org/mem"
 	"inet.af/netaddr"
 	"tailscale.com/derp/derphttp"
-	"tailscale.com/net/dnscache"
 	"tailscale.com/net/interfaces"
 	"tailscale.com/net/netns"
 	"tailscale.com/net/stun"
@@ -134,10 +133,6 @@ func cloneDurationMap(m map[int]time.Duration) map[int]time.Duration {
 
 // Client generates a netcheck Report.
 type Client struct {
-	// DNSCache optionally specifies a DNSCache to use.
-	// If nil, a DNS cache is not used.
-	DNSCache *dnscache.Resolver
-
 	// Verbose enables verbose logging.
 	Verbose bool
 
@@ -697,7 +692,7 @@ func (rs *reportState) probePortMapServices() {
 	port1900 := netaddr.IPPort{IP: gw, Port: 1900}.UDPAddr()
 	port5351 := netaddr.IPPort{IP: gw, Port: 5351}.UDPAddr()
 
-	rs.c.logf("probePortMapServices: me %v -> gw %v", myIP, gw)
+	rs.c.logf("[v1] probePortMapServices: me %v -> gw %v", myIP, gw)
 
 	// Create a UDP4 socket used just for querying for UPnP, NAT-PMP, and PCP.
 	uc, err := netns.Listener().ListenPacket(context.Background(), "udp4", ":0")
@@ -715,6 +710,7 @@ func (rs *reportState) probePortMapServices() {
 	uc.WriteTo(pcpPacket(myIP, tempPort, false), port5351)
 
 	res := make([]byte, 1500)
+	sentPCPDelete := false
 	for {
 		n, addr, err := uc.ReadFrom(res)
 		if err != nil {
@@ -732,11 +728,14 @@ func (rs *reportState) probePortMapServices() {
 			if n == 60 && res[0] == 0x02 { // right length and version 2
 				rs.setOptBool(&rs.report.PCP, true)
 
-				// And now delete the mapping.
-				// (PCP is the only protocol of the three that requires
-				// we cause a side effect to detect whether it's present,
-				// so we need to redo that side effect now.)
-				uc.WriteTo(pcpPacket(myIP, tempPort, true), port5351)
+				if !sentPCPDelete {
+					sentPCPDelete = true
+					// And now delete the mapping.
+					// (PCP is the only protocol of the three that requires
+					// we cause a side effect to detect whether it's present,
+					// so we need to redo that side effect now.)
+					uc.WriteTo(pcpPacket(myIP, tempPort, true), port5351)
+				}
 			}
 		}
 	}
@@ -752,6 +751,7 @@ var uPnPPacket = []byte("M-SEARCH * HTTP/1.1\r\n" +
 
 var v4unspec, _ = netaddr.ParseIP("0.0.0.0")
 
+// pcpPacket generates a PCP packet with a MAP opcode.
 func pcpPacket(myIP netaddr.IP, mapToLocalPort int, delete bool) []byte {
 	const udpProtoNumber = 17
 	lifetimeSeconds := uint32(1)
@@ -759,17 +759,24 @@ func pcpPacket(myIP netaddr.IP, mapToLocalPort int, delete bool) []byte {
 		lifetimeSeconds = 0
 	}
 	const opMap = 1
+
+	// 24 byte header + 36 byte map opcode
 	pkt := make([]byte, (32+32+128)/8+(96+8+24+16+16+128)/8)
+
+	// The header (https://tools.ietf.org/html/rfc6887#section-7.1)
 	pkt[0] = 2 // version
 	pkt[1] = opMap
 	binary.BigEndian.PutUint32(pkt[4:8], lifetimeSeconds)
 	myIP16 := myIP.As16()
 	copy(pkt[8:], myIP16[:])
-	rand.Read(pkt[24 : 24+12])
-	pkt[36] = udpProtoNumber
-	binary.BigEndian.PutUint16(pkt[40:], uint16(mapToLocalPort))
+
+	// The map opcode body (https://tools.ietf.org/html/rfc6887#section-11.1)
+	mapOp := pkt[24:]
+	rand.Read(mapOp[:12]) // 96 bit mappping nonce
+	mapOp[12] = udpProtoNumber
+	binary.BigEndian.PutUint16(mapOp[16:], uint16(mapToLocalPort))
 	v4unspec16 := v4unspec.As16()
-	copy(pkt[40:], v4unspec16[:])
+	copy(mapOp[20:], v4unspec16[:])
 	return pkt
 }
 
@@ -835,7 +842,7 @@ func (c *Client) GetReport(ctx context.Context, dm *tailcfg.DERPMap) (*Report, e
 
 	ifState, err := interfaces.GetState()
 	if err != nil {
-		c.logf("interfaces: %v", err)
+		c.logf("[v1] interfaces: %v", err)
 		return nil, err
 	}
 
@@ -944,7 +951,7 @@ func (c *Client) GetReport(ctx context.Context, dm *tailcfg.DERPMap) (*Report, e
 			go func(reg *tailcfg.DERPRegion) {
 				defer wg.Done()
 				if d, ip, err := c.measureHTTPSLatency(ctx, reg); err != nil {
-					c.logf("netcheck: measuring HTTPS latency of %v (%d): %v", reg.RegionCode, reg.RegionID, err)
+					c.logf("[v1] netcheck: measuring HTTPS latency of %v (%d): %v", reg.RegionCode, reg.RegionID, err)
 				} else {
 					rs.mu.Lock()
 					rs.report.RegionLatency[reg.RegionID] = d
@@ -1038,7 +1045,7 @@ func (c *Client) measureHTTPSLatency(ctx context.Context, reg *tailcfg.DERPRegio
 }
 
 func (c *Client) logConciseReport(r *Report, dm *tailcfg.DERPMap) {
-	c.logf("%v", logger.ArgWriter(func(w *bufio.Writer) {
+	c.logf("[v1] report: %v", logger.ArgWriter(func(w *bufio.Writer) {
 		fmt.Fprintf(w, "udp=%v", r.UDP)
 		if !r.IPv4 {
 			fmt.Fprintf(w, " v4=%v", r.IPv4)
@@ -1095,6 +1102,10 @@ func (c *Client) addReportHistoryAndSetPreferredDERP(r *Report) {
 	c.mu.Lock()
 	defer c.mu.Unlock()
 
+	var prevDERP int
+	if c.last != nil {
+		prevDERP = c.last.PreferredDERP
+	}
 	if c.prev == nil {
 		c.prev = map[time.Time]*Report{}
 	}
@@ -1112,9 +1123,9 @@ func (c *Client) addReportHistoryAndSetPreferredDERP(r *Report) {
 			delete(c.prev, t)
 			continue
 		}
-		for hp, d := range pr.RegionLatency {
-			if bd, ok := bestRecent[hp]; !ok || d < bd {
-				bestRecent[hp] = d
+		for regionID, d := range pr.RegionLatency {
+			if bd, ok := bestRecent[regionID]; !ok || d < bd {
+				bestRecent[regionID] = d
 			}
 		}
 	}
@@ -1122,13 +1133,27 @@ func (c *Client) addReportHistoryAndSetPreferredDERP(r *Report) {
 	// Then, pick which currently-alive DERP server from the
 	// current report has the best latency over the past maxAge.
 	var bestAny time.Duration
-	for hp := range r.RegionLatency {
-		best := bestRecent[hp]
+	var oldRegionCurLatency time.Duration
+	for regionID, d := range r.RegionLatency {
+		if regionID == prevDERP {
+			oldRegionCurLatency = d
+		}
+		best := bestRecent[regionID]
 		if r.PreferredDERP == 0 || best < bestAny {
 			bestAny = best
-			r.PreferredDERP = hp
+			r.PreferredDERP = regionID
 		}
 	}
+
+	// If we're changing our preferred DERP but the old one's still
+	// accessible and the new one's not much better, just stick with
+	// where we are.
+	if prevDERP != 0 &&
+		r.PreferredDERP != prevDERP &&
+		oldRegionCurLatency != 0 &&
+		bestAny > oldRegionCurLatency/3*2 {
+		r.PreferredDERP = prevDERP
+	}
 }
 
 func updateLatency(m map[int]time.Duration, regionID int, d time.Duration) {

net/netcheck/netcheck_test.go

@@ -195,6 +195,24 @@ func TestAddReportHistoryAndSetPreferredDERP(t *testing.T) {
 			wantPrevLen: 1, // t=[0123]s all gone. (too old, older than 10 min)
 			wantDERP:    3, // only option
 		},
+		{
+			name: "preferred_derp_hysteresis_no_switch",
+			steps: []step{
+				{0 * time.Second, report("d1", 4, "d2", 5)},
+				{1 * time.Second, report("d1", 4, "d2", 3)},
+			},
+			wantPrevLen: 2,
+			wantDERP:    1, // 2 didn't get fast enough
+		},
+		{
+			name: "preferred_derp_hysteresis_do_switch",
+			steps: []step{
+				{0 * time.Second, report("d1", 4, "d2", 5)},
+				{1 * time.Second, report("d1", 4, "d2", 1)},
+			},
+			wantPrevLen: 2,
+			wantDERP:    2, // 2 got fast enough
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -554,9 +572,47 @@ func TestLogConciseReport(t *testing.T) {
 			var buf bytes.Buffer
 			c := &Client{Logf: func(f string, a ...interface{}) { fmt.Fprintf(&buf, f, a...) }}
 			c.logConciseReport(tt.r, dm)
-			if got := buf.String(); got != tt.want {
+			if got := strings.TrimPrefix(buf.String(), "[v1] report: "); got != tt.want {
 				t.Errorf("unexpected result.\n got: %#q\nwant: %#q\n", got, tt.want)
 			}
 		})
 	}
 }
+
+func TestSortRegions(t *testing.T) {
+	unsortedMap := &tailcfg.DERPMap{
+		Regions: map[int]*tailcfg.DERPRegion{},
+	}
+	for rid := 1; rid <= 5; rid++ {
+		var nodes []*tailcfg.DERPNode
+		nodes = append(nodes, &tailcfg.DERPNode{
+			Name:     fmt.Sprintf("%da", rid),
+			RegionID: rid,
+			HostName: fmt.Sprintf("derp%d-1", rid),
+			IPv4:     fmt.Sprintf("%d.0.0.1", rid),
+			IPv6:     fmt.Sprintf("%d::1", rid),
+		})
+		unsortedMap.Regions[rid] = &tailcfg.DERPRegion{
+			RegionID: rid,
+			Nodes:    nodes,
+		}
+	}
+	report := newReport()
+	report.RegionLatency[1] = time.Second * time.Duration(5)
+	report.RegionLatency[2] = time.Second * time.Duration(3)
+	report.RegionLatency[3] = time.Second * time.Duration(6)
+	report.RegionLatency[4] = time.Second * time.Duration(0)
+	report.RegionLatency[5] = time.Second * time.Duration(2)
+	sortedMap := sortRegions(unsortedMap, report)
+
+	// Sorting by latency this should result in rid: 5, 2, 1, 3
+	// rid 4 with latency 0 should be at the end
+	want := []int{5, 2, 1, 3, 4}
+	got := make([]int, len(sortedMap))
+	for i, r := range sortedMap {
+		got[i] = r.RegionID
+	}
+	if !reflect.DeepEqual(got, want) {
+		t.Errorf("got %v; want %v", got, want)
+	}
+}

net/netstat/netstat_windows.go

@@ -93,7 +93,7 @@ func (t *Table) addEntries(fam int) error {
 	}
 	buf = buf[:size]
 
-	numEntries := *(*uint32)(unsafe.Pointer(&buf[0]))
+	numEntries := endian.Native.Uint32(buf[:4])
 	buf = buf[4:]
 
 	var recSize int

net/nettest/pipe.go

@@ -60,7 +60,7 @@ func (p *Pipe) Read(b []byte) (n int, err error) {
 	for {
 		p.mu.Lock()
 		closed := p.closed
-		timedout := !p.readTimeout.IsZero() && time.Now().After(p.readTimeout)
+		timedout := !p.readTimeout.IsZero() && !time.Now().Before(p.readTimeout)
 		blocked := p.blocked
 		if !closed && !timedout && len(p.buf) > 0 {
 			n2 := copy(b, p.buf)
@@ -99,7 +99,7 @@ func (p *Pipe) Write(b []byte) (n int, err error) {
 	for {
 		p.mu.Lock()
 		closed := p.closed
-		timedout := !p.writeTimeout.IsZero() && time.Now().After(p.writeTimeout)
+		timedout := !p.writeTimeout.IsZero() && !time.Now().Before(p.writeTimeout)
 		blocked := p.blocked
 		if !closed && !timedout {
 			n2 := len(b)

net/nettest/pipe_test.go

@@ -35,7 +35,7 @@ func TestPipeTimeout(t *testing.T) {
 		p := NewPipe("p1", 1<<16)
 		p.SetWriteDeadline(time.Now().Add(-1 * time.Second))
 		n, err := p.Write([]byte{'h'})
-		if err == nil || !errors.Is(err, ErrWriteTimeout) || !errors.Is(err, ErrTimeout) {
+		if !errors.Is(err, ErrWriteTimeout) || !errors.Is(err, ErrTimeout) {
 			t.Errorf("missing write timeout got err: %v", err)
 		}
 		if n != 0 {
@@ -49,7 +49,7 @@ func TestPipeTimeout(t *testing.T) {
 		p.SetReadDeadline(time.Now().Add(-1 * time.Second))
 		b := make([]byte, 1)
 		n, err := p.Read(b)
-		if err == nil || !errors.Is(err, ErrReadTimeout) || !errors.Is(err, ErrTimeout) {
+		if !errors.Is(err, ErrReadTimeout) || !errors.Is(err, ErrTimeout) {
 			t.Errorf("missing read timeout got err: %v", err)
 		}
 		if n != 0 {
@@ -65,7 +65,7 @@ func TestPipeTimeout(t *testing.T) {
 		if err := p.Block(); err != nil {
 			t.Fatal(err)
 		}
-		if _, err := p.Write([]byte{'h'}); err == nil || !errors.Is(err, ErrWriteTimeout) {
+		if _, err := p.Write([]byte{'h'}); !errors.Is(err, ErrWriteTimeout) {
 			t.Fatalf("want write timeout got: %v", err)
 		}
 	})
@@ -80,11 +80,10 @@ func TestPipeTimeout(t *testing.T) {
 		if err := p.Block(); err != nil {
 			t.Fatal(err)
 		}
-		if _, err := p.Read(b); err == nil || !errors.Is(err, ErrReadTimeout) {
+		if _, err := p.Read(b); !errors.Is(err, ErrReadTimeout) {
 			t.Fatalf("want read timeout got: %v", err)
 		}
 	})
-
 }
 
 func TestLimit(t *testing.T) {
@@ -117,4 +116,8 @@ func TestLimit(t *testing.T) {
 	} else if n != 1 {
 		t.Errorf("Read(%q): n=%d want 1", string(b), n)
 	}
+
+	if err := <-errCh; err != nil {
+		t.Error(err)
+	}
 }

net/packet/doc.go

@@ -0,0 +1,16 @@
+// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package packet contains packet parsing and marshaling utilities.
+//
+// Parsed provides allocation-free minimal packet header decoding, for
+// use in packet filtering. The other types in the package are for
+// constructing and marshaling packets into []bytes.
+//
+// To support allocation-free parsing, this package defines IPv4 and
+// IPv6 address types. You should prefer to use netaddr's types,
+// except where you absolutely need allocation-free IP handling
+// (i.e. in the tunnel datapath) and are willing to implement all
+// codepaths and data structures twice, once per IP family.
+package packet

net/packet/header.go

@@ -16,27 +16,31 @@ const tcpHeaderLength = 20
 const maxPacketLength = math.MaxUint16
 
 var (
+	// errSmallBuffer is returned when Marshal receives a buffer
+	// too small to contain the header to marshal.
 	errSmallBuffer = errors.New("buffer too small")
+	// errLargePacket is returned when Marshal receives a payload
+	// larger than the maximum representable size in header
+	// fields.
 	errLargePacket = errors.New("packet too large")
 )
 
-// Header is a packet header capable of marshaling itself into a byte buffer.
+// Header is a packet header capable of marshaling itself into a byte
+// buffer.
 type Header interface {
-	// Len returns the length of the header after marshaling.
+	// Len returns the length of the marshaled packet.
 	Len() int
-	// Marshal serializes the header into buf in wire format.
-	// It clobbers the header region, which is the first h.Length() bytes of buf.
-	// It explicitly initializes every byte of the header region,
-	// so pre-zeroing it on reuse is not required. It does not allocate memory.
-	// It fails if and only if len(buf) < Length().
+	// Marshal serializes the header into buf, which must be at
+	// least Len() bytes long. Implementations of Marshal assume
+	// that bytes after the first Len() are payload bytes for the
+	// purpose of computing length and checksum fields. Marshal
+	// implementations must not allocate memory.
 	Marshal(buf []byte) error
-	// ToResponse transforms the header into one for a response packet.
-	// For instance, this swaps the source and destination IPs.
-	ToResponse()
 }
 
-// Generate generates a new packet with the given header and payload.
-// Unlike Header.Marshal, this does allocate memory.
+// Generate generates a new packet with the given Header and
+// payload. This function allocates memory, see Header.Marshal for an
+// allocation-free option.
 func Generate(h Header, payload []byte) []byte {
 	hlen := h.Len()
 	buf := make([]byte, hlen+len(payload))

net/packet/icmp4.go

@@ -0,0 +1,90 @@
+// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package packet
+
+import "encoding/binary"
+
+// icmp4HeaderLength is the size of the ICMPv4 packet header, not
+// including the outer IP layer or the variable "response data"
+// trailer.
+const icmp4HeaderLength = 4
+
+// ICMP4Type is an ICMPv4 type, as specified in
+// https://www.iana.org/assignments/icmp-parameters/icmp-parameters.xhtml
+type ICMP4Type uint8
+
+const (
+	ICMP4EchoReply    ICMP4Type = 0x00
+	ICMP4EchoRequest  ICMP4Type = 0x08
+	ICMP4Unreachable  ICMP4Type = 0x03
+	ICMP4TimeExceeded ICMP4Type = 0x0b
+)
+
+func (t ICMP4Type) String() string {
+	switch t {
+	case ICMP4EchoReply:
+		return "EchoReply"
+	case ICMP4EchoRequest:
+		return "EchoRequest"
+	case ICMP4Unreachable:
+		return "Unreachable"
+	case ICMP4TimeExceeded:
+		return "TimeExceeded"
+	default:
+		return "Unknown"
+	}
+}
+
+// ICMP4Code is an ICMPv4 code, as specified in
+// https://www.iana.org/assignments/icmp-parameters/icmp-parameters.xhtml
+type ICMP4Code uint8
+
+const (
+	ICMP4NoCode ICMP4Code = 0
+)
+
+// ICMP4Header is an IPv4+ICMPv4 header.
+type ICMP4Header struct {
+	IP4Header
+	Type ICMP4Type
+	Code ICMP4Code
+}
+
+// Len implements Header.
+func (h ICMP4Header) Len() int {
+	return h.IP4Header.Len() + icmp4HeaderLength
+}
+
+// Marshal implements Header.
+func (h ICMP4Header) Marshal(buf []byte) error {
+	if len(buf) < h.Len() {
+		return errSmallBuffer
+	}
+	if len(buf) > maxPacketLength {
+		return errLargePacket
+	}
+	// The caller does not need to set this.
+	h.IPProto = ICMPv4
+
+	buf[20] = uint8(h.Type)
+	buf[21] = uint8(h.Code)
+
+	h.IP4Header.Marshal(buf)
+
+	binary.BigEndian.PutUint16(buf[22:24], ip4Checksum(buf))
+
+	return nil
+}
+
+// ToResponse implements Header. TODO: it doesn't implement it
+// correctly, instead it statically generates an ICMP Echo Reply
+// packet.
+func (h *ICMP4Header) ToResponse() {
+	// TODO: this doesn't implement ToResponse correctly, as it
+	// assumes the ICMP request type.
+	h.Type = ICMP4EchoReply
+	h.Code = ICMP4NoCode
+	h.IP4Header.ToResponse()
+}

net/packet/icmp6.go

@@ -0,0 +1,44 @@
+// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package packet
+
+// icmp6HeaderLength is the size of the ICMPv6 packet header, not
+// including the outer IP layer or the variable "response data"
+// trailer.
+const icmp6HeaderLength = 4
+
+// ICMP6Type is an ICMPv6 type, as specified in
+// https://www.iana.org/assignments/icmpv6-parameters/icmpv6-parameters.xhtml
+type ICMP6Type uint8
+
+const (
+	ICMP6Unreachable  ICMP6Type = 1
+	ICMP6TimeExceeded ICMP6Type = 3
+	ICMP6EchoRequest  ICMP6Type = 128
+	ICMP6EchoReply    ICMP6Type = 129
+)
+
+func (t ICMP6Type) String() string {
+	switch t {
+	case ICMP6Unreachable:
+		return "Unreachable"
+	case ICMP6TimeExceeded:
+		return "TimeExceeded"
+	case ICMP6EchoRequest:
+		return "EchoRequest"
+	case ICMP6EchoReply:
+		return "EchoReply"
+	default:
+		return "Unknown"
+	}
+}
+
+// ICMP6Code is an ICMPv6 code, as specified in
+// https://www.iana.org/assignments/icmpv6-parameters/icmpv6-parameters.xhtml
+type ICMP6Code uint8
+
+const (
+	ICMP6NoCode ICMP6Code = 0
+)

net/packet/ip.go

@@ -0,0 +1,66 @@
+// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package packet
+
+// IPProto is an IP subprotocol as defined by the IANA protocol
+// numbers list
+// (https://www.iana.org/assignments/protocol-numbers/protocol-numbers.xhtml),
+// or the special values Unknown or Fragment.
+type IPProto uint8
+
+const (
+	// Unknown represents an unknown or unsupported protocol; it's
+	// deliberately the zero value. Strictly speaking the zero
+	// value is IPv6 hop-by-hop extensions, but we don't support
+	// those, so this is still technically correct.
+	Unknown IPProto = 0x00
+
+	// Values from the IANA registry.
+	ICMPv4 IPProto = 0x01
+	IGMP   IPProto = 0x02
+	ICMPv6 IPProto = 0x3a
+	TCP    IPProto = 0x06
+	UDP    IPProto = 0x11
+
+	// TSMP is the Tailscale Message Protocol (our ICMP-ish
+	// thing), an IP protocol used only between Tailscale nodes
+	// (still encrypted by WireGuard) that communicates why things
+	// failed, etc.
+	//
+	// Proto number 99 is reserved for "any private encryption
+	// scheme". We never accept these from the host OS stack nor
+	// send them to the host network stack. It's only used between
+	// nodes.
+	TSMP IPProto = 99
+
+	// Fragment represents any non-first IP fragment, for which we
+	// don't have the sub-protocol header (and therefore can't
+	// figure out what the sub-protocol is).
+	//
+	// 0xFF is reserved in the IANA registry, so we steal it for
+	// internal use.
+	Fragment IPProto = 0xFF
+)
+
+func (p IPProto) String() string {
+	switch p {
+	case Fragment:
+		return "Frag"
+	case ICMPv4:
+		return "ICMPv4"
+	case IGMP:
+		return "IGMP"
+	case ICMPv6:
+		return "ICMPv6"
+	case UDP:
+		return "UDP"
+	case TCP:
+		return "TCP"
+	case TSMP:
+		return "TSMP"
+	default:
+		return "Unknown"
+	}
+}

net/packet/ip4.go

@@ -0,0 +1,116 @@
+// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package packet
+
+import (
+	"encoding/binary"
+	"errors"
+
+	"inet.af/netaddr"
+)
+
+// ip4HeaderLength is the length of an IPv4 header with no IP options.
+const ip4HeaderLength = 20
+
+// IP4Header represents an IPv4 packet header.
+type IP4Header struct {
+	IPProto IPProto
+	IPID    uint16
+	Src     netaddr.IP
+	Dst     netaddr.IP
+}
+
+// Len implements Header.
+func (h IP4Header) Len() int {
+	return ip4HeaderLength
+}
+
+var errWrongFamily = errors.New("wrong address family for src/dst IP")
+
+// Marshal implements Header.
+func (h IP4Header) Marshal(buf []byte) error {
+	if len(buf) < h.Len() {
+		return errSmallBuffer
+	}
+	if len(buf) > maxPacketLength {
+		return errLargePacket
+	}
+	if !h.Src.Is4() || !h.Dst.Is4() {
+		return errWrongFamily
+	}
+
+	buf[0] = 0x40 | (byte(h.Len() >> 2))                   // IPv4 + IHL
+	buf[1] = 0x00                                          // DSCP + ECN
+	binary.BigEndian.PutUint16(buf[2:4], uint16(len(buf))) // Total length
+	binary.BigEndian.PutUint16(buf[4:6], h.IPID)           // ID
+	binary.BigEndian.PutUint16(buf[6:8], 0)                // Flags + fragment offset
+	buf[8] = 64                                            // TTL
+	buf[9] = uint8(h.IPProto)                              // Inner protocol
+	// Blank checksum. This is necessary even though we overwrite
+	// it later, because the checksum computation runs over these
+	// bytes and expects them to be zero.
+	binary.BigEndian.PutUint16(buf[10:12], 0)
+	src := h.Src.As4()
+	dst := h.Dst.As4()
+	copy(buf[12:16], src[:])
+	copy(buf[16:20], dst[:])
+
+	binary.BigEndian.PutUint16(buf[10:12], ip4Checksum(buf[0:20])) // Checksum
+
+	return nil
+}
+
+// ToResponse implements Header.
+func (h *IP4Header) ToResponse() {
+	h.Src, h.Dst = h.Dst, h.Src
+	// Flip the bits in the IPID. If incoming IPIDs are distinct, so are these.
+	h.IPID = ^h.IPID
+}
+
+// ip4Checksum computes an IPv4 checksum, as specified in
+// https://tools.ietf.org/html/rfc1071
+func ip4Checksum(b []byte) uint16 {
+	var ac uint32
+	i := 0
+	n := len(b)
+	for n >= 2 {
+		ac += uint32(binary.BigEndian.Uint16(b[i : i+2]))
+		n -= 2
+		i += 2
+	}
+	if n == 1 {
+		ac += uint32(b[i]) << 8
+	}
+	for (ac >> 16) > 0 {
+		ac = (ac >> 16) + (ac & 0xffff)
+	}
+	return uint16(^ac)
+}
+
+// ip4PseudoHeaderOffset is the number of bytes by which the IPv4 UDP
+// pseudo-header is smaller than the real IPv4 header.
+const ip4PseudoHeaderOffset = 8
+
+// marshalPseudo serializes h into buf in the "pseudo-header" form
+// required when calculating UDP checksums. The pseudo-header starts
+// at buf[ip4PseudoHeaderOffset] so as to abut the following UDP
+// header, while leaving enough space in buf for a full IPv4 header.
+func (h IP4Header) marshalPseudo(buf []byte) error {
+	if len(buf) < h.Len() {
+		return errSmallBuffer
+	}
+	if len(buf) > maxPacketLength {
+		return errLargePacket
+	}
+
+	length := len(buf) - h.Len()
+	src, dst := h.Src.As4(), h.Dst.As4()
+	copy(buf[8:12], src[:])
+	copy(buf[12:16], dst[:])
+	buf[16] = 0x0
+	buf[17] = uint8(h.IPProto)
+	binary.BigEndian.PutUint16(buf[18:20], uint16(length))
+	return nil
+}

net/packet/ip6.go

@@ -0,0 +1,76 @@
+// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package packet
+
+import (
+	"encoding/binary"
+
+	"inet.af/netaddr"
+)
+
+// ip6HeaderLength is the length of an IPv6 header with no IP options.
+const ip6HeaderLength = 40
+
+// IP6Header represents an IPv6 packet header.
+type IP6Header struct {
+	IPProto IPProto
+	IPID    uint32 // only lower 20 bits used
+	Src     netaddr.IP
+	Dst     netaddr.IP
+}
+
+// Len implements Header.
+func (h IP6Header) Len() int {
+	return ip6HeaderLength
+}
+
+// Marshal implements Header.
+func (h IP6Header) Marshal(buf []byte) error {
+	if len(buf) < h.Len() {
+		return errSmallBuffer
+	}
+	if len(buf) > maxPacketLength {
+		return errLargePacket
+	}
+
+	binary.BigEndian.PutUint32(buf[:4], h.IPID&0x000FFFFF)
+	buf[0] = 0x60
+	binary.BigEndian.PutUint16(buf[4:6], uint16(len(buf)-ip6HeaderLength)) // Total length
+	buf[6] = uint8(h.IPProto)                                              // Inner protocol
+	buf[7] = 64                                                            // TTL
+	src, dst := h.Src.As16(), h.Dst.As16()
+	copy(buf[8:24], src[:])
+	copy(buf[24:40], dst[:])
+
+	return nil
+}
+
+// ToResponse implements Header.
+func (h *IP6Header) ToResponse() {
+	h.Src, h.Dst = h.Dst, h.Src
+	// Flip the bits in the IPID. If incoming IPIDs are distinct, so are these.
+	h.IPID = (^h.IPID) & 0x000FFFFF
+}
+
+// marshalPseudo serializes h into buf in the "pseudo-header" form
+// required when calculating UDP checksums.
+func (h IP6Header) marshalPseudo(buf []byte) error {
+	if len(buf) < h.Len() {
+		return errSmallBuffer
+	}
+	if len(buf) > maxPacketLength {
+		return errLargePacket
+	}
+
+	src, dst := h.Src.As16(), h.Dst.As16()
+	copy(buf[:16], src[:])
+	copy(buf[16:32], dst[:])
+	binary.BigEndian.PutUint32(buf[32:36], uint32(len(buf)-h.Len()))
+	buf[36] = 0
+	buf[37] = 0
+	buf[38] = 0
+	buf[39] = 17 // NextProto
+	return nil
+}

net/packet/packet.go

@@ -0,0 +1,435 @@
+// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package packet
+
+import (
+	"encoding/binary"
+	"fmt"
+	"net"
+	"strings"
+
+	"inet.af/netaddr"
+	"tailscale.com/types/strbuilder"
+)
+
+// RFC1858: prevent overlapping fragment attacks.
+const minFrag = 60 + 20 // max IPv4 header + basic TCP header
+
+type TCPFlag uint8
+
+const (
+	TCPFin    TCPFlag = 0x01
+	TCPSyn    TCPFlag = 0x02
+	TCPRst    TCPFlag = 0x04
+	TCPPsh    TCPFlag = 0x08
+	TCPAck    TCPFlag = 0x10
+	TCPSynAck TCPFlag = TCPSyn | TCPAck
+)
+
+// Parsed is a minimal decoding of a packet suitable for use in filters.
+type Parsed struct {
+	// b is the byte buffer that this decodes.
+	b []byte
+	// subofs is the offset of IP subprotocol.
+	subofs int
+	// dataofs is the offset of IP subprotocol payload.
+	dataofs int
+	// length is the total length of the packet.
+	// This is not the same as len(b) because b can have trailing zeros.
+	length int
+
+	// IPVersion is the IP protocol version of the packet (4 or
+	// 6), or 0 if the packet doesn't look like IPv4 or IPv6.
+	IPVersion uint8
+	// IPProto is the IP subprotocol (UDP, TCP, etc.). Valid iff IPVersion != 0.
+	IPProto IPProto
+	// SrcIP4 is the source address. Family matches IPVersion. Port is
+	// valid iff IPProto == TCP || IPProto == UDP.
+	Src netaddr.IPPort
+	// DstIP4 is the destination address. Family matches IPVersion.
+	Dst netaddr.IPPort
+	// TCPFlags is the packet's TCP flag bigs. Valid iff IPProto == TCP.
+	TCPFlags TCPFlag
+}
+
+func (p *Parsed) String() string {
+	if p.IPVersion != 4 && p.IPVersion != 6 {
+		return "Unknown{???}"
+	}
+
+	sb := strbuilder.Get()
+	sb.WriteString(p.IPProto.String())
+	sb.WriteByte('{')
+	writeIPPort(sb, p.Src)
+	sb.WriteString(" > ")
+	writeIPPort(sb, p.Dst)
+	sb.WriteByte('}')
+	return sb.String()
+}
+
+// writeIPPort writes ipp.String() into sb, with fewer allocations.
+//
+// TODO: make netaddr more efficient in this area, and retire this func.
+func writeIPPort(sb *strbuilder.Builder, ipp netaddr.IPPort) {
+	if ipp.IP.Is4() {
+		raw := ipp.IP.As4()
+		sb.WriteUint(uint64(raw[0]))
+		sb.WriteByte('.')
+		sb.WriteUint(uint64(raw[1]))
+		sb.WriteByte('.')
+		sb.WriteUint(uint64(raw[2]))
+		sb.WriteByte('.')
+		sb.WriteUint(uint64(raw[3]))
+		sb.WriteByte(':')
+	} else {
+		sb.WriteByte('[')
+		sb.WriteString(ipp.IP.String()) // TODO: faster?
+		sb.WriteString("]:")
+	}
+	sb.WriteUint(uint64(ipp.Port))
+}
+
+// Decode extracts data from the packet in b into q.
+// It performs extremely simple packet decoding for basic IPv4 packet types.
+// It extracts only the subprotocol id, IP addresses, and (if any) ports,
+// and shouldn't need any memory allocation.
+func (q *Parsed) Decode(b []byte) {
+	q.b = b
+
+	if len(b) < 1 {
+		q.IPVersion = 0
+		q.IPProto = Unknown
+		return
+	}
+
+	q.IPVersion = b[0] >> 4
+	switch q.IPVersion {
+	case 4:
+		q.decode4(b)
+	case 6:
+		q.decode6(b)
+	default:
+		q.IPVersion = 0
+		q.IPProto = Unknown
+	}
+}
+
+func (q *Parsed) decode4(b []byte) {
+	if len(b) < ip4HeaderLength {
+		q.IPVersion = 0
+		q.IPProto = Unknown
+		return
+	}
+
+	// Check that it's IPv4.
+	q.IPProto = IPProto(b[9])
+	q.length = int(binary.BigEndian.Uint16(b[2:4]))
+	if len(b) < q.length {
+		// Packet was cut off before full IPv4 length.
+		q.IPProto = Unknown
+		return
+	}
+
+	// If it's valid IPv4, then the IP addresses are valid
+	q.Src.IP = netaddr.IPv4(b[12], b[13], b[14], b[15])
+	q.Dst.IP = netaddr.IPv4(b[16], b[17], b[18], b[19])
+
+	q.subofs = int((b[0] & 0x0F) << 2)
+	if q.subofs > q.length {
+		// next-proto starts beyond end of packet.
+		q.IPProto = Unknown
+		return
+	}
+	sub := b[q.subofs:]
+	sub = sub[:len(sub):len(sub)] // help the compiler do bounds check elimination
+
+	// We don't care much about IP fragmentation, except insofar as it's
+	// used for firewall bypass attacks. The trick is make the first
+	// fragment of a TCP or UDP packet so short that it doesn't fit
+	// the TCP or UDP header, so we can't read the port, in hope that
+	// it'll sneak past. Then subsequent fragments fill it in, but we're
+	// missing the first part of the header, so we can't read that either.
+	//
+	// A "perfectly correct" implementation would have to reassemble
+	// fragments before deciding what to do. But the truth is there's
+	// zero reason to send such a short first fragment, so we can treat
+	// it as Unknown. We can also treat any subsequent fragment that starts
+	// at such a low offset as Unknown.
+	fragFlags := binary.BigEndian.Uint16(b[6:8])
+	moreFrags := (fragFlags & 0x20) != 0
+	fragOfs := fragFlags & 0x1FFF
+	if fragOfs == 0 {
+		// This is the first fragment
+		if moreFrags && len(sub) < minFrag {
+			// Suspiciously short first fragment, dump it.
+			q.IPProto = Unknown
+			return
+		}
+		// otherwise, this is either non-fragmented (the usual case)
+		// or a big enough initial fragment that we can read the
+		// whole subprotocol header.
+		switch q.IPProto {
+		case ICMPv4:
+			if len(sub) < icmp4HeaderLength {
+				q.IPProto = Unknown
+				return
+			}
+			q.Src.Port = 0
+			q.Dst.Port = 0
+			q.dataofs = q.subofs + icmp4HeaderLength
+			return
+		case IGMP:
+			// Keep IPProto, but don't parse anything else
+			// out.
+			return
+		case TCP:
+			if len(sub) < tcpHeaderLength {
+				q.IPProto = Unknown
+				return
+			}
+			q.Src.Port = binary.BigEndian.Uint16(sub[0:2])
+			q.Dst.Port = binary.BigEndian.Uint16(sub[2:4])
+			q.TCPFlags = TCPFlag(sub[13]) & 0x3F
+			headerLength := (sub[12] & 0xF0) >> 2
+			q.dataofs = q.subofs + int(headerLength)
+			return
+		case UDP:
+			if len(sub) < udpHeaderLength {
+				q.IPProto = Unknown
+				return
+			}
+			q.Src.Port = binary.BigEndian.Uint16(sub[0:2])
+			q.Dst.Port = binary.BigEndian.Uint16(sub[2:4])
+			q.dataofs = q.subofs + udpHeaderLength
+			return
+		case TSMP:
+			// Inter-tailscale messages.
+			q.dataofs = q.subofs
+			return
+		default:
+			q.IPProto = Unknown
+			return
+		}
+	} else {
+		// This is a fragment other than the first one.
+		if fragOfs < minFrag {
+			// First frag was suspiciously short, so we can't
+			// trust the followup either.
+			q.IPProto = Unknown
+			return
+		}
+		// otherwise, we have to permit the fragment to slide through.
+		// Second and later fragments don't have sub-headers.
+		// Ideally, we would drop fragments that we can't identify,
+		// but that would require statefulness. Anyway, receivers'
+		// kernels know to drop fragments where the initial fragment
+		// doesn't arrive.
+		q.IPProto = Fragment
+		return
+	}
+}
+
+func (q *Parsed) decode6(b []byte) {
+	if len(b) < ip6HeaderLength {
+		q.IPVersion = 0
+		q.IPProto = Unknown
+		return
+	}
+
+	q.IPProto = IPProto(b[6])
+	q.length = int(binary.BigEndian.Uint16(b[4:6])) + ip6HeaderLength
+	if len(b) < q.length {
+		// Packet was cut off before the full IPv6 length.
+		q.IPProto = Unknown
+		return
+	}
+
+	// okay to ignore `ok` here, because IPs pulled from packets are
+	// always well-formed stdlib IPs.
+	q.Src.IP, _ = netaddr.FromStdIP(net.IP(b[8:24]))
+	q.Dst.IP, _ = netaddr.FromStdIP(net.IP(b[24:40]))
+
+	// We don't support any IPv6 extension headers. Don't try to
+	// be clever. Therefore, the IP subprotocol always starts at
+	// byte 40.
+	//
+	// Note that this means we don't support fragmentation in
+	// IPv6. This is fine, because IPv6 strongly mandates that you
+	// should not fragment, which makes fragmentation on the open
+	// internet extremely uncommon.
+	//
+	// This also means we don't support IPSec headers (AH/ESP), or
+	// IPv6 jumbo frames. Those will get marked Unknown and
+	// dropped.
+	q.subofs = 40
+	sub := b[q.subofs:]
+	sub = sub[:len(sub):len(sub)] // help the compiler do bounds check elimination
+
+	switch q.IPProto {
+	case ICMPv6:
+		if len(sub) < icmp6HeaderLength {
+			q.IPProto = Unknown
+			return
+		}
+		q.Src.Port = 0
+		q.Dst.Port = 0
+		q.dataofs = q.subofs + icmp6HeaderLength
+	case TCP:
+		if len(sub) < tcpHeaderLength {
+			q.IPProto = Unknown
+			return
+		}
+		q.Src.Port = binary.BigEndian.Uint16(sub[0:2])
+		q.Dst.Port = binary.BigEndian.Uint16(sub[2:4])
+		q.TCPFlags = TCPFlag(sub[13]) & 0x3F
+		headerLength := (sub[12] & 0xF0) >> 2
+		q.dataofs = q.subofs + int(headerLength)
+		return
+	case UDP:
+		if len(sub) < udpHeaderLength {
+			q.IPProto = Unknown
+			return
+		}
+		q.Src.Port = binary.BigEndian.Uint16(sub[0:2])
+		q.Dst.Port = binary.BigEndian.Uint16(sub[2:4])
+		q.dataofs = q.subofs + udpHeaderLength
+	case TSMP:
+		// Inter-tailscale messages.
+		q.dataofs = q.subofs
+		return
+	default:
+		q.IPProto = Unknown
+		return
+	}
+}
+
+func (q *Parsed) IP4Header() IP4Header {
+	if q.IPVersion != 4 {
+		panic("IP4Header called on non-IPv4 Parsed")
+	}
+	ipid := binary.BigEndian.Uint16(q.b[4:6])
+	return IP4Header{
+		IPID:    ipid,
+		IPProto: q.IPProto,
+		Src:     q.Src.IP,
+		Dst:     q.Dst.IP,
+	}
+}
+
+func (q *Parsed) ICMP4Header() ICMP4Header {
+	if q.IPVersion != 4 {
+		panic("IP4Header called on non-IPv4 Parsed")
+	}
+	return ICMP4Header{
+		IP4Header: q.IP4Header(),
+		Type:      ICMP4Type(q.b[q.subofs+0]),
+		Code:      ICMP4Code(q.b[q.subofs+1]),
+	}
+}
+
+func (q *Parsed) UDP4Header() UDP4Header {
+	if q.IPVersion != 4 {
+		panic("IP4Header called on non-IPv4 Parsed")
+	}
+	return UDP4Header{
+		IP4Header: q.IP4Header(),
+		SrcPort:   q.Src.Port,
+		DstPort:   q.Dst.Port,
+	}
+}
+
+// Buffer returns the entire packet buffer.
+// This is a read-only view; that is, q retains the ownership of the buffer.
+func (q *Parsed) Buffer() []byte {
+	return q.b
+}
+
+// Payload returns the payload of the IP subprotocol section.
+// This is a read-only view; that is, q retains the ownership of the buffer.
+func (q *Parsed) Payload() []byte {
+	return q.b[q.dataofs:q.length]
+}
+
+// IsTCPSyn reports whether q is a TCP SYN packet
+// (i.e. the first packet in a new connection).
+func (q *Parsed) IsTCPSyn() bool {
+	return (q.TCPFlags & TCPSynAck) == TCPSyn
+}
+
+// IsError reports whether q is an ICMP "Error" packet.
+func (q *Parsed) IsError() bool {
+	switch q.IPProto {
+	case ICMPv4:
+		if len(q.b) < q.subofs+8 {
+			return false
+		}
+		t := ICMP4Type(q.b[q.subofs])
+		return t == ICMP4Unreachable || t == ICMP4TimeExceeded
+	case ICMPv6:
+		if len(q.b) < q.subofs+8 {
+			return false
+		}
+		t := ICMP6Type(q.b[q.subofs])
+		return t == ICMP6Unreachable || t == ICMP6TimeExceeded
+	default:
+		return false
+	}
+}
+
+// IsEchoRequest reports whether q is an ICMP Echo Request.
+func (q *Parsed) IsEchoRequest() bool {
+	switch q.IPProto {
+	case ICMPv4:
+		return len(q.b) >= q.subofs+8 && ICMP4Type(q.b[q.subofs]) == ICMP4EchoRequest && ICMP4Code(q.b[q.subofs+1]) == ICMP4NoCode
+	case ICMPv6:
+		return len(q.b) >= q.subofs+8 && ICMP6Type(q.b[q.subofs]) == ICMP6EchoRequest && ICMP6Code(q.b[q.subofs+1]) == ICMP6NoCode
+	default:
+		return false
+	}
+}
+
+// IsEchoRequest reports whether q is an IPv4 ICMP Echo Response.
+func (q *Parsed) IsEchoResponse() bool {
+	switch q.IPProto {
+	case ICMPv4:
+		return len(q.b) >= q.subofs+8 && ICMP4Type(q.b[q.subofs]) == ICMP4EchoReply && ICMP4Code(q.b[q.subofs+1]) == ICMP4NoCode
+	case ICMPv6:
+		return len(q.b) >= q.subofs+8 && ICMP6Type(q.b[q.subofs]) == ICMP6EchoReply && ICMP6Code(q.b[q.subofs+1]) == ICMP6NoCode
+	default:
+		return false
+	}
+}
+
+func Hexdump(b []byte) string {
+	out := new(strings.Builder)
+	for i := 0; i < len(b); i += 16 {
+		if i > 0 {
+			fmt.Fprintf(out, "\n")
+		}
+		fmt.Fprintf(out, "  %04x  ", i)
+		j := 0
+		for ; j < 16 && i+j < len(b); j++ {
+			if j == 8 {
+				fmt.Fprintf(out, " ")
+			}
+			fmt.Fprintf(out, "%02x ", b[i+j])
+		}
+		for ; j < 16; j++ {
+			if j == 8 {
+				fmt.Fprintf(out, " ")
+			}
+			fmt.Fprintf(out, "   ")
+		}
+		fmt.Fprintf(out, " ")
+		for j = 0; j < 16 && i+j < len(b); j++ {
+			if b[i+j] >= 32 && b[i+j] < 128 {
+				fmt.Fprintf(out, "%c", b[i+j])
+			} else {
+				fmt.Fprintf(out, ".")
+			}
+		}
+	}
+	return out.String()
+}

net/packet/packet_test.go

@@ -0,0 +1,486 @@
+// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package packet
+
+import (
+	"bytes"
+	"reflect"
+	"testing"
+
+	"inet.af/netaddr"
+)
+
+func mustIPPort(s string) netaddr.IPPort {
+	ipp, err := netaddr.ParseIPPort(s)
+	if err != nil {
+		panic(err)
+	}
+	return ipp
+}
+
+var icmp4RequestBuffer = []byte{
+	// IP header up to checksum
+	0x45, 0x00, 0x00, 0x27, 0xde, 0xad, 0x00, 0x00, 0x40, 0x01, 0x8c, 0x15,
+	// source ip
+	0x01, 0x02, 0x03, 0x04,
+	// destination ip
+	0x05, 0x06, 0x07, 0x08,
+	// ICMP header
+	0x08, 0x00, 0x7d, 0x22,
+	// "request_payload"
+	0x72, 0x65, 0x71, 0x75, 0x65, 0x73, 0x74, 0x5f, 0x70, 0x61, 0x79, 0x6c, 0x6f, 0x61, 0x64,
+}
+
+var icmp4RequestDecode = Parsed{
+	b:       icmp4RequestBuffer,
+	subofs:  20,
+	dataofs: 24,
+	length:  len(icmp4RequestBuffer),
+
+	IPVersion: 4,
+	IPProto:   ICMPv4,
+	Src:       mustIPPort("1.2.3.4:0"),
+	Dst:       mustIPPort("5.6.7.8:0"),
+}
+
+var icmp4ReplyBuffer = []byte{
+	0x45, 0x00, 0x00, 0x25, 0x21, 0x52, 0x00, 0x00, 0x40, 0x01, 0x49, 0x73,
+	// source ip
+	0x05, 0x06, 0x07, 0x08,
+	// destination ip
+	0x01, 0x02, 0x03, 0x04,
+	// ICMP header
+	0x00, 0x00, 0xe6, 0x9e,
+	// "reply_payload"
+	0x72, 0x65, 0x70, 0x6c, 0x79, 0x5f, 0x70, 0x61, 0x79, 0x6c, 0x6f, 0x61, 0x64,
+}
+
+var icmp4ReplyDecode = Parsed{
+	b:       icmp4ReplyBuffer,
+	subofs:  20,
+	dataofs: 24,
+	length:  len(icmp4ReplyBuffer),
+
+	IPVersion: 4,
+	IPProto:   ICMPv4,
+	Src:       mustIPPort("1.2.3.4:0"),
+	Dst:       mustIPPort("5.6.7.8:0"),
+}
+
+// ICMPv6 Router Solicitation
+var icmp6PacketBuffer = []byte{
+	0x60, 0x00, 0x00, 0x00, 0x00, 0x08, 0x3a, 0xff,
+	0xfe, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	0xfb, 0x57, 0x1d, 0xea, 0x9c, 0x39, 0x8f, 0xb7,
+	0xff, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02,
+	0x85, 0x00, 0x38, 0x04, 0x00, 0x00, 0x00, 0x00,
+}
+
+var icmp6PacketDecode = Parsed{
+	b:         icmp6PacketBuffer,
+	subofs:    40,
+	dataofs:   44,
+	length:    len(icmp6PacketBuffer),
+	IPVersion: 6,
+	IPProto:   ICMPv6,
+	Src:       mustIPPort("[fe80::fb57:1dea:9c39:8fb7]:0"),
+	Dst:       mustIPPort("[ff02::2]:0"),
+}
+
+// This is a malformed IPv4 packet.
+// Namely, the string "tcp_payload" follows the first byte of the IPv4 header.
+var unknownPacketBuffer = []byte{
+	0x45, 0x74, 0x63, 0x70, 0x5f, 0x70, 0x61, 0x79, 0x6c, 0x6f, 0x61, 0x64,
+}
+
+var unknownPacketDecode = Parsed{
+	b:         unknownPacketBuffer,
+	IPVersion: 0,
+	IPProto:   Unknown,
+}
+
+var tcp4PacketBuffer = []byte{
+	// IP header up to checksum
+	0x45, 0x00, 0x00, 0x37, 0xde, 0xad, 0x00, 0x00, 0x40, 0x06, 0x49, 0x5f,
+	// source ip
+	0x01, 0x02, 0x03, 0x04,
+	// destination ip
+	0x05, 0x06, 0x07, 0x08,
+	// TCP header with SYN, ACK set
+	0x00, 0x7b, 0x02, 0x37, 0x00, 0x00, 0x12, 0x34, 0x00, 0x00, 0x00, 0x00,
+	0x50, 0x12, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00,
+	// "request_payload"
+	0x72, 0x65, 0x71, 0x75, 0x65, 0x73, 0x74, 0x5f, 0x70, 0x61, 0x79, 0x6c, 0x6f, 0x61, 0x64,
+}
+
+var tcp4PacketDecode = Parsed{
+	b:       tcp4PacketBuffer,
+	subofs:  20,
+	dataofs: 40,
+	length:  len(tcp4PacketBuffer),
+
+	IPVersion: 4,
+	IPProto:   TCP,
+	Src:       mustIPPort("1.2.3.4:123"),
+	Dst:       mustIPPort("5.6.7.8:567"),
+	TCPFlags:  TCPSynAck,
+}
+
+var tcp6RequestBuffer = []byte{
+	// IPv6 header up to hop limit
+	0x60, 0x06, 0xef, 0xcc, 0x00, 0x28, 0x06, 0x40,
+	// Src addr
+	0x20, 0x01, 0x05, 0x59, 0xbc, 0x13, 0x54, 0x00, 0x17, 0x49, 0x46, 0x28, 0x39, 0x34, 0x0e, 0x1b,
+	// Dst addr
+	0x26, 0x07, 0xf8, 0xb0, 0x40, 0x0a, 0x08, 0x09, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x20, 0x0e,
+	// TCP SYN segment, no payload
+	0xa4, 0x60, 0x00, 0x50, 0xf3, 0x82, 0xa1, 0x25, 0x00, 0x00, 0x00, 0x00, 0xa0, 0x02, 0xfd, 0x20,
+	0xb1, 0xc6, 0x00, 0x00, 0x02, 0x04, 0x05, 0xa0, 0x04, 0x02, 0x08, 0x0a, 0xca, 0x76, 0xa6, 0x8e,
+	0x00, 0x00, 0x00, 0x00, 0x01, 0x03, 0x03, 0x07,
+}
+
+var tcp6RequestDecode = Parsed{
+	b:       tcp6RequestBuffer,
+	subofs:  40,
+	dataofs: len(tcp6RequestBuffer),
+	length:  len(tcp6RequestBuffer),
+
+	IPVersion: 6,
+	IPProto:   TCP,
+	Src:       mustIPPort("[2001:559:bc13:5400:1749:4628:3934:e1b]:42080"),
+	Dst:       mustIPPort("[2607:f8b0:400a:809::200e]:80"),
+	TCPFlags:  TCPSyn,
+}
+
+var udp4RequestBuffer = []byte{
+	// IP header up to checksum
+	0x45, 0x00, 0x00, 0x2b, 0xde, 0xad, 0x00, 0x00, 0x40, 0x11, 0x8c, 0x01,
+	// source ip
+	0x01, 0x02, 0x03, 0x04,
+	// destination ip
+	0x05, 0x06, 0x07, 0x08,
+	// UDP header
+	0x00, 0x7b, 0x02, 0x37, 0x00, 0x17, 0x72, 0x1d,
+	// "request_payload"
+	0x72, 0x65, 0x71, 0x75, 0x65, 0x73, 0x74, 0x5f, 0x70, 0x61, 0x79, 0x6c, 0x6f, 0x61, 0x64,
+}
+
+var udp4RequestDecode = Parsed{
+	b:       udp4RequestBuffer,
+	subofs:  20,
+	dataofs: 28,
+	length:  len(udp4RequestBuffer),
+
+	IPVersion: 4,
+	IPProto:   UDP,
+	Src:       mustIPPort("1.2.3.4:123"),
+	Dst:       mustIPPort("5.6.7.8:567"),
+}
+
+var invalid4RequestBuffer = []byte{
+	// IP header up to checksum. IHL field points beyond end of packet.
+	0x4a, 0x00, 0x00, 0x14, 0xde, 0xad, 0x00, 0x00, 0x40, 0x11, 0x8c, 0x01,
+	// source ip
+	0x01, 0x02, 0x03, 0x04,
+	// destination ip
+	0x05, 0x06, 0x07, 0x08,
+}
+
+// Regression check for the IHL field pointing beyond the end of the
+// packet.
+var invalid4RequestDecode = Parsed{
+	b:      invalid4RequestBuffer,
+	subofs: 40,
+	length: len(invalid4RequestBuffer),
+
+	IPVersion: 4,
+	IPProto:   Unknown,
+	Src:       mustIPPort("1.2.3.4:0"),
+	Dst:       mustIPPort("5.6.7.8:0"),
+}
+
+var udp6RequestBuffer = []byte{
+	// IPv6 header up to hop limit
+	0x60, 0x0e, 0xc9, 0x67, 0x00, 0x29, 0x11, 0x40,
+	// Src addr
+	0x20, 0x01, 0x05, 0x59, 0xbc, 0x13, 0x54, 0x00, 0x17, 0x49, 0x46, 0x28, 0x39, 0x34, 0x0e, 0x1b,
+	// Dst addr
+	0x26, 0x07, 0xf8, 0xb0, 0x40, 0x0a, 0x08, 0x09, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x20, 0x0e,
+	// UDP header
+	0xd4, 0x04, 0x01, 0xbb, 0x00, 0x29, 0x96, 0x84,
+	// Payload
+	0x5c, 0x06, 0xae, 0x85, 0x02, 0xf5, 0xdb, 0x90, 0xe0, 0xe0, 0x93, 0xed, 0x9a, 0xd9, 0x92, 0x69, 0xbe, 0x36, 0x8a, 0x7d, 0xd7, 0xce, 0xd0, 0x8a, 0xf2, 0x51, 0x95, 0xff, 0xb6, 0x92, 0x70, 0x10, 0xd7,
+}
+
+var udp6RequestDecode = Parsed{
+	b:       udp6RequestBuffer,
+	subofs:  40,
+	dataofs: 48,
+	length:  len(udp6RequestBuffer),
+
+	IPVersion: 6,
+	IPProto:   UDP,
+	Src:       mustIPPort("[2001:559:bc13:5400:1749:4628:3934:e1b]:54276"),
+	Dst:       mustIPPort("[2607:f8b0:400a:809::200e]:443"),
+}
+
+var udp4ReplyBuffer = []byte{
+	// IP header up to checksum
+	0x45, 0x00, 0x00, 0x29, 0x21, 0x52, 0x00, 0x00, 0x40, 0x11, 0x49, 0x5f,
+	// source ip
+	0x05, 0x06, 0x07, 0x08,
+	// destination ip
+	0x01, 0x02, 0x03, 0x04,
+	// UDP header
+	0x02, 0x37, 0x00, 0x7b, 0x00, 0x15, 0xd3, 0x9d,
+	// "reply_payload"
+	0x72, 0x65, 0x70, 0x6c, 0x79, 0x5f, 0x70, 0x61, 0x79, 0x6c, 0x6f, 0x61, 0x64,
+}
+
+var udp4ReplyDecode = Parsed{
+	b:       udp4ReplyBuffer,
+	subofs:  20,
+	dataofs: 28,
+	length:  len(udp4ReplyBuffer),
+
+	IPProto: UDP,
+	Src:     mustIPPort("1.2.3.4:567"),
+	Dst:     mustIPPort("5.6.7.8:123"),
+}
+
+var igmpPacketBuffer = []byte{
+	// IP header up to checksum
+	0x46, 0xc0, 0x00, 0x20, 0x00, 0x00, 0x40, 0x00, 0x01, 0x02, 0x41, 0x22,
+	// source IP
+	0xc0, 0xa8, 0x01, 0x52,
+	// destination IP
+	0xe0, 0x00, 0x00, 0xfb,
+	// IGMP Membership Report
+	0x94, 0x04, 0x00, 0x00, 0x16, 0x00, 0x09, 0x04, 0xe0, 0x00, 0x00, 0xfb,
+	//0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+}
+
+var igmpPacketDecode = Parsed{
+	b:      igmpPacketBuffer,
+	subofs: 24,
+	length: len(igmpPacketBuffer),
+
+	IPVersion: 4,
+	IPProto:   IGMP,
+	Src:       mustIPPort("192.168.1.82:0"),
+	Dst:       mustIPPort("224.0.0.251:0"),
+}
+
+var ipv4TSMPBuffer = []byte{
+	// IPv4 header:
+	0x45, 0x00,
+	0x00, 0x1b, // 20 + 7 bytes total
+	0x00, 0x00, // ID
+	0x00, 0x00, // Fragment
+	0x40, // TTL
+	byte(TSMP),
+	0x5f, 0xc3, // header checksum (wrong here)
+	// source IP:
+	0x64, 0x5e, 0x0c, 0x0e,
+	// dest IP:
+	0x64, 0x4a, 0x46, 0x03,
+	byte(TSMPTypeRejectedConn),
+	byte(TCP),
+	byte(RejectedDueToACLs),
+	0x00, 123, // src port
+	0x00, 80, // dst port
+}
+
+var ipv4TSMPDecode = Parsed{
+	b:         ipv4TSMPBuffer,
+	subofs:    20,
+	dataofs:   20,
+	length:    27,
+	IPVersion: 4,
+	IPProto:   TSMP,
+	Src:       mustIPPort("100.94.12.14:0"),
+	Dst:       mustIPPort("100.74.70.3:0"),
+}
+
+func TestParsedString(t *testing.T) {
+	tests := []struct {
+		name    string
+		qdecode Parsed
+		want    string
+	}{
+		{"tcp4", tcp4PacketDecode, "TCP{1.2.3.4:123 > 5.6.7.8:567}"},
+		{"tcp6", tcp6RequestDecode, "TCP{[2001:559:bc13:5400:1749:4628:3934:e1b]:42080 > [2607:f8b0:400a:809::200e]:80}"},
+		{"udp4", udp4RequestDecode, "UDP{1.2.3.4:123 > 5.6.7.8:567}"},
+		{"udp6", udp6RequestDecode, "UDP{[2001:559:bc13:5400:1749:4628:3934:e1b]:54276 > [2607:f8b0:400a:809::200e]:443}"},
+		{"icmp4", icmp4RequestDecode, "ICMPv4{1.2.3.4:0 > 5.6.7.8:0}"},
+		{"icmp6", icmp6PacketDecode, "ICMPv6{[fe80::fb57:1dea:9c39:8fb7]:0 > [ff02::2]:0}"},
+		{"igmp", igmpPacketDecode, "IGMP{192.168.1.82:0 > 224.0.0.251:0}"},
+		{"unknown", unknownPacketDecode, "Unknown{???}"},
+		{"ipv4_tsmp", ipv4TSMPDecode, "TSMP{100.94.12.14:0 > 100.74.70.3:0}"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := tt.qdecode.String()
+			if got != tt.want {
+				t.Errorf("got %q; want %q", got, tt.want)
+			}
+		})
+	}
+
+	var sink string
+	allocs := testing.AllocsPerRun(1000, func() {
+		sink = tests[0].qdecode.String()
+	})
+	_ = sink
+	if allocs != 1 {
+		t.Errorf("allocs = %v; want 1", allocs)
+	}
+}
+
+func TestDecode(t *testing.T) {
+	tests := []struct {
+		name string
+		buf  []byte
+		want Parsed
+	}{
+		{"icmp4", icmp4RequestBuffer, icmp4RequestDecode},
+		{"icmp6", icmp6PacketBuffer, icmp6PacketDecode},
+		{"tcp4", tcp4PacketBuffer, tcp4PacketDecode},
+		{"tcp6", tcp6RequestBuffer, tcp6RequestDecode},
+		{"udp4", udp4RequestBuffer, udp4RequestDecode},
+		{"udp6", udp6RequestBuffer, udp6RequestDecode},
+		{"igmp", igmpPacketBuffer, igmpPacketDecode},
+		{"unknown", unknownPacketBuffer, unknownPacketDecode},
+		{"invalid4", invalid4RequestBuffer, invalid4RequestDecode},
+		{"ipv4_tsmp", ipv4TSMPBuffer, ipv4TSMPDecode},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var got Parsed
+			got.Decode(tt.buf)
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("mismatch\n got: %s %#v\nwant: %s %#v", got.String(), got, tt.want.String(), tt.want)
+			}
+		})
+	}
+
+	allocs := testing.AllocsPerRun(1000, func() {
+		var got Parsed
+		got.Decode(tests[0].buf)
+	})
+	if allocs != 0 {
+		t.Errorf("allocs = %v; want 0", allocs)
+	}
+}
+
+func BenchmarkDecode(b *testing.B) {
+	benches := []struct {
+		name string
+		buf  []byte
+	}{
+		{"tcp4", tcp4PacketBuffer},
+		{"tcp6", tcp6RequestBuffer},
+		{"udp4", udp4RequestBuffer},
+		{"udp6", udp6RequestBuffer},
+		{"icmp4", icmp4RequestBuffer},
+		{"icmp6", icmp6PacketBuffer},
+		{"igmp", igmpPacketBuffer},
+		{"unknown", unknownPacketBuffer},
+	}
+
+	for _, bench := range benches {
+		b.Run(bench.name, func(b *testing.B) {
+			b.ReportAllocs()
+			for i := 0; i < b.N; i++ {
+				var p Parsed
+				p.Decode(bench.buf)
+			}
+		})
+	}
+}
+
+func TestMarshalRequest(t *testing.T) {
+	// Too small to hold our packets, but only barely.
+	var small [20]byte
+	var large [64]byte
+
+	icmpHeader := icmp4RequestDecode.ICMP4Header()
+	udpHeader := udp4RequestDecode.UDP4Header()
+	tests := []struct {
+		name   string
+		header Header
+		want   []byte
+	}{
+		{"icmp", &icmpHeader, icmp4RequestBuffer},
+		{"udp", &udpHeader, udp4RequestBuffer},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			err := tt.header.Marshal(small[:])
+			if err != errSmallBuffer {
+				t.Errorf("got err: nil; want: %s", errSmallBuffer)
+			}
+
+			dataOffset := tt.header.Len()
+			dataLength := copy(large[dataOffset:], []byte("request_payload"))
+			end := dataOffset + dataLength
+			err = tt.header.Marshal(large[:end])
+
+			if err != nil {
+				t.Errorf("got err: %s; want nil", err)
+			}
+
+			if !bytes.Equal(large[:end], tt.want) {
+				t.Errorf("got %x; want %x", large[:end], tt.want)
+			}
+		})
+	}
+}
+
+func TestMarshalResponse(t *testing.T) {
+	var buf [64]byte
+
+	icmpHeader := icmp4RequestDecode.ICMP4Header()
+	udpHeader := udp4RequestDecode.UDP4Header()
+
+	type HeaderToResponser interface {
+		Header
+		// ToResponse transforms the header into one for a response packet.
+		// For instance, this swaps the source and destination IPs.
+		ToResponse()
+	}
+
+	tests := []struct {
+		name   string
+		header HeaderToResponser
+		want   []byte
+	}{
+		{"icmp", &icmpHeader, icmp4ReplyBuffer},
+		{"udp", &udpHeader, udp4ReplyBuffer},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			tt.header.ToResponse()
+
+			dataOffset := tt.header.Len()
+			dataLength := copy(buf[dataOffset:], []byte("reply_payload"))
+			end := dataOffset + dataLength
+			err := tt.header.Marshal(buf[:end])
+
+			if err != nil {
+				t.Errorf("got err: %s; want nil", err)
+			}
+
+			if !bytes.Equal(buf[:end], tt.want) {
+				t.Errorf("got %x; want %x", buf[:end], tt.want)
+			}
+		})
+	}
+}

net/packet/tsmp.go

@@ -0,0 +1,140 @@
+// Copyright (c) 2021 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// TSMP is our ICMP-like "Tailscale Message Protocol" for signaling
+// Tailscale-specific messages between nodes. It uses IP protocol 99
+// (reserved for "any private encryption scheme") within
+// Wireguard's normal encryption between peers and never hits the host
+// network stack.
+
+package packet
+
+import (
+	"encoding/binary"
+	"errors"
+	"fmt"
+
+	"inet.af/netaddr"
+	"tailscale.com/net/flowtrack"
+)
+
+// TailscaleRejectedHeader is a TSMP message that says that one
+// Tailscale node has rejected the connection from another. Unlike a
+// TCP RST, this includes a reason.
+//
+// On the wire, after the IP header, it's currently 7 bytes:
+//     * '!'
+//     * IPProto byte (IANA protocol number: TCP or UDP)
+//     * 'A' or 'S' (RejectedDueToACLs, RejectedDueToShieldsUp)
+//     * srcPort big endian uint16
+//     * dstPort big endian uint16
+//
+// In the future it might also accept 16 byte IP flow src/dst IPs
+// after the header, if they're different than the IP-level ones.
+type TailscaleRejectedHeader struct {
+	IPSrc  netaddr.IP            // IPv4 or IPv6 header's src IP
+	IPDst  netaddr.IP            // IPv4 or IPv6 header's dst IP
+	Src    netaddr.IPPort        // rejected flow's src
+	Dst    netaddr.IPPort        // rejected flow's dst
+	Proto  IPProto               // proto that was rejected (TCP or UDP)
+	Reason TailscaleRejectReason // why the connection was rejected
+}
+
+func (rh TailscaleRejectedHeader) Flow() flowtrack.Tuple {
+	return flowtrack.Tuple{Src: rh.Src, Dst: rh.Dst}
+}
+
+func (rh TailscaleRejectedHeader) String() string {
+	return fmt.Sprintf("TSMP-reject-flow{%s %s > %s}: %s", rh.Proto, rh.Src, rh.Dst, rh.Reason)
+}
+
+type TSMPType uint8
+
+const (
+	TSMPTypeRejectedConn TSMPType = '!'
+)
+
+type TailscaleRejectReason byte
+
+const (
+	RejectedDueToACLs      TailscaleRejectReason = 'A'
+	RejectedDueToShieldsUp TailscaleRejectReason = 'S'
+)
+
+func (r TailscaleRejectReason) String() string {
+	switch r {
+	case RejectedDueToACLs:
+		return "acl"
+	case RejectedDueToShieldsUp:
+		return "shields"
+	}
+	return fmt.Sprintf("0x%02x", byte(r))
+}
+
+func (h TailscaleRejectedHeader) Len() int {
+	var ipHeaderLen int
+	if h.IPSrc.Is4() {
+		ipHeaderLen = ip4HeaderLength
+	} else if h.IPSrc.Is6() {
+		ipHeaderLen = ip6HeaderLength
+	}
+	return ipHeaderLen +
+		1 + // TSMPType byte
+		1 + // IPProto byte
+		1 + // TailscaleRejectReason byte
+		2*2 // 2 uint16 ports
+}
+
+func (h TailscaleRejectedHeader) Marshal(buf []byte) error {
+	if len(buf) < h.Len() {
+		return errSmallBuffer
+	}
+	if len(buf) > maxPacketLength {
+		return errLargePacket
+	}
+	if h.Src.IP.Is4() {
+		iph := IP4Header{
+			IPProto: TSMP,
+			Src:     h.IPSrc,
+			Dst:     h.IPDst,
+		}
+		iph.Marshal(buf)
+		buf = buf[ip4HeaderLength:]
+	} else if h.Src.IP.Is6() {
+		iph := IP6Header{
+			IPProto: TSMP,
+			Src:     h.IPSrc,
+			Dst:     h.IPDst,
+		}
+		iph.Marshal(buf)
+		buf = buf[ip6HeaderLength:]
+	} else {
+		return errors.New("bogus src IP")
+	}
+	buf[0] = byte(TSMPTypeRejectedConn)
+	buf[1] = byte(h.Proto)
+	buf[2] = byte(h.Reason)
+	binary.BigEndian.PutUint16(buf[3:5], h.Src.Port)
+	binary.BigEndian.PutUint16(buf[5:7], h.Dst.Port)
+	return nil
+}
+
+// AsTailscaleRejectedHeader parses pp as an incoming rejection
+// connection TSMP message.
+//
+// ok reports whether pp was a valid TSMP rejection packet.
+func (pp *Parsed) AsTailscaleRejectedHeader() (h TailscaleRejectedHeader, ok bool) {
+	p := pp.Payload()
+	if len(p) < 7 || p[0] != byte(TSMPTypeRejectedConn) {
+		return
+	}
+	return TailscaleRejectedHeader{
+		Proto:  IPProto(p[1]),
+		Reason: TailscaleRejectReason(p[2]),
+		IPSrc:  pp.Src.IP,
+		IPDst:  pp.Dst.IP,
+		Src:    netaddr.IPPort{IP: pp.Dst.IP, Port: binary.BigEndian.Uint16(p[3:5])},
+		Dst:    netaddr.IPPort{IP: pp.Src.IP, Port: binary.BigEndian.Uint16(p[5:7])},
+	}, true
+}

net/packet/tsmp_test.go

@@ -0,0 +1,63 @@
+// Copyright (c) 2021 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package packet
+
+import (
+	"testing"
+
+	"inet.af/netaddr"
+)
+
+func TestTailscaleRejectedHeader(t *testing.T) {
+	tests := []struct {
+		h       TailscaleRejectedHeader
+		wantStr string
+	}{
+		{
+			h: TailscaleRejectedHeader{
+				IPSrc:  netaddr.MustParseIP("5.5.5.5"),
+				IPDst:  netaddr.MustParseIP("1.2.3.4"),
+				Src:    netaddr.MustParseIPPort("1.2.3.4:567"),
+				Dst:    netaddr.MustParseIPPort("5.5.5.5:443"),
+				Proto:  TCP,
+				Reason: RejectedDueToACLs,
+			},
+			wantStr: "TSMP-reject-flow{TCP 1.2.3.4:567 > 5.5.5.5:443}: acl",
+		},
+		{
+			h: TailscaleRejectedHeader{
+				IPSrc:  netaddr.MustParseIP("2::2"),
+				IPDst:  netaddr.MustParseIP("1::1"),
+				Src:    netaddr.MustParseIPPort("[1::1]:567"),
+				Dst:    netaddr.MustParseIPPort("[2::2]:443"),
+				Proto:  UDP,
+				Reason: RejectedDueToShieldsUp,
+			},
+			wantStr: "TSMP-reject-flow{UDP [1::1]:567 > [2::2]:443}: shields",
+		},
+	}
+	for i, tt := range tests {
+		gotStr := tt.h.String()
+		if gotStr != tt.wantStr {
+			t.Errorf("%v. String = %q; want %q", i, gotStr, tt.wantStr)
+			continue
+		}
+		pkt := make([]byte, tt.h.Len())
+		tt.h.Marshal(pkt)
+
+		var p Parsed
+		p.Decode(pkt)
+		t.Logf("Parsed: %+v", p)
+		t.Logf("Parsed: %s", p.String())
+		back, ok := p.AsTailscaleRejectedHeader()
+		if !ok {
+			t.Errorf("%v. %q (%02x) didn't parse back", i, gotStr, pkt)
+			continue
+		}
+		if back != tt.h {
+			t.Errorf("%v. %q parsed back as %q", i, tt.h, back)
+		}
+	}
+}

net/packet/udp4.go

@@ -0,0 +1,55 @@
+// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package packet
+
+import "encoding/binary"
+
+// udpHeaderLength is the size of the UDP packet header, not including
+// the outer IP header.
+const udpHeaderLength = 8
+
+// UDP4Header is an IPv4+UDP header.
+type UDP4Header struct {
+	IP4Header
+	SrcPort uint16
+	DstPort uint16
+}
+
+// Len implements Header.
+func (h UDP4Header) Len() int {
+	return h.IP4Header.Len() + udpHeaderLength
+}
+
+// Marshal implements Header.
+func (h UDP4Header) Marshal(buf []byte) error {
+	if len(buf) < h.Len() {
+		return errSmallBuffer
+	}
+	if len(buf) > maxPacketLength {
+		return errLargePacket
+	}
+	// The caller does not need to set this.
+	h.IPProto = UDP
+
+	length := len(buf) - h.IP4Header.Len()
+	binary.BigEndian.PutUint16(buf[20:22], h.SrcPort)
+	binary.BigEndian.PutUint16(buf[22:24], h.DstPort)
+	binary.BigEndian.PutUint16(buf[24:26], uint16(length))
+	binary.BigEndian.PutUint16(buf[26:28], 0) // blank checksum
+
+	// UDP checksum with IP pseudo header.
+	h.IP4Header.marshalPseudo(buf)
+	binary.BigEndian.PutUint16(buf[26:28], ip4Checksum(buf[ip4PseudoHeaderOffset:]))
+
+	h.IP4Header.Marshal(buf)
+
+	return nil
+}
+
+// ToResponse implements Header.
+func (h *UDP4Header) ToResponse() {
+	h.SrcPort, h.DstPort = h.DstPort, h.SrcPort
+	h.IP4Header.ToResponse()
+}

net/packet/udp6.go

@@ -0,0 +1,51 @@
+// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package packet
+
+import "encoding/binary"
+
+// UDP6Header is an IPv6+UDP header.
+type UDP6Header struct {
+	IP6Header
+	SrcPort uint16
+	DstPort uint16
+}
+
+// Len implements Header.
+func (h UDP6Header) Len() int {
+	return h.IP6Header.Len() + udpHeaderLength
+}
+
+// Marshal implements Header.
+func (h UDP6Header) Marshal(buf []byte) error {
+	if len(buf) < h.Len() {
+		return errSmallBuffer
+	}
+	if len(buf) > maxPacketLength {
+		return errLargePacket
+	}
+	// The caller does not need to set this.
+	h.IPProto = UDP
+
+	length := len(buf) - h.IP6Header.Len()
+	binary.BigEndian.PutUint16(buf[40:42], h.SrcPort)
+	binary.BigEndian.PutUint16(buf[42:44], h.DstPort)
+	binary.BigEndian.PutUint16(buf[44:46], uint16(length))
+	binary.BigEndian.PutUint16(buf[46:48], 0) // blank checksum
+
+	// UDP checksum with IP pseudo header.
+	h.IP6Header.marshalPseudo(buf)
+	binary.BigEndian.PutUint16(buf[46:48], ip4Checksum(buf[:]))
+
+	h.IP6Header.Marshal(buf)
+
+	return nil
+}
+
+// ToResponse implements Header.
+func (h *UDP6Header) ToResponse() {
+	h.SrcPort, h.DstPort = h.DstPort, h.SrcPort
+	h.IP6Header.ToResponse()
+}

net/tsaddr/tsaddr_test.go

@@ -4,7 +4,32 @@
 
 package tsaddr
 
-import "testing"
+import (
+	"testing"
+
+	"inet.af/netaddr"
+)
+
+func TestInCrostiniRange(t *testing.T) {
+	tests := []struct {
+		ip   netaddr.IP
+		want bool
+	}{
+		{netaddr.IPv4(192, 168, 0, 1), false},
+		{netaddr.IPv4(100, 101, 102, 103), false},
+		{netaddr.IPv4(100, 115, 92, 0), true},
+		{netaddr.IPv4(100, 115, 92, 5), true},
+		{netaddr.IPv4(100, 115, 92, 255), true},
+		{netaddr.IPv4(100, 115, 93, 40), true},
+		{netaddr.IPv4(100, 115, 94, 1), false},
+	}
+
+	for _, test := range tests {
+		if got := ChromeOSVMRange().Contains(test.ip); got != test.want {
+			t.Errorf("inCrostiniRange(%q) = %v, want %v", test.ip, got, test.want)
+		}
+	}
+}
 
 func TestChromeOSVMRange(t *testing.T) {
 	if got, want := ChromeOSVMRange().String(), "100.115.92.0/23"; got != want {

portlist/netstat_exec.go

@@ -8,9 +8,8 @@ package portlist
 
 import (
 	"fmt"
+	"os/exec"
 	"strings"
-
-	exec "tailscale.com/tempfork/osexec"
 )
 
 var osHideWindow func(*exec.Cmd) // non-nil on Windows; see portlist_windows.go

portlist/poller.go

@@ -7,7 +7,6 @@ package portlist
 import (
 	"context"
 	"errors"
-	"runtime"
 	"time"
 
 	"tailscale.com/version"
@@ -34,7 +33,7 @@ type Poller struct {
 // NewPoller returns a new portlist Poller. It returns an error
 // if the portlist couldn't be obtained.
 func NewPoller() (*Poller, error) {
-	if runtime.GOOS == "darwin" && version.IsMobile() {
+	if version.OS() == "iOS" {
 		return nil, errors.New("not available on iOS")
 	}
 	p := &Poller{

portlist/portlist_macos.go

@@ -12,11 +12,10 @@ import (
 	"fmt"
 	"log"
 	"os"
+	"os/exec"
 	"strings"
 	"sync/atomic"
 	"time"
-
-	exec "tailscale.com/tempfork/osexec"
 )
 
 // We have to run netstat, which is a bit expensive, so don't do it too often.

portlist/portlist_test.go

@@ -47,6 +47,153 @@ func TestIgnoreLocallyBoundPorts(t *testing.T) {
 	}
 }
 
+func TestLessThan(t *testing.T) {
+	tests := []struct {
+		name string
+		a, b Port
+		want bool
+	}{
+		{
+			"Port a < b",
+			Port{Proto: "tcp", Port: 100, Process: "proc1", inode: "inode1"},
+			Port{Proto: "tcp", Port: 101, Process: "proc1", inode: "inode1"},
+			true,
+		},
+		{
+			"Port a > b",
+			Port{Proto: "tcp", Port: 101, Process: "proc1", inode: "inode1"},
+			Port{Proto: "tcp", Port: 100, Process: "proc1", inode: "inode1"},
+			false,
+		},
+		{
+			"Proto a < b",
+			Port{Proto: "tcp", Port: 100, Process: "proc1", inode: "inode1"},
+			Port{Proto: "udp", Port: 100, Process: "proc1", inode: "inode1"},
+			true,
+		},
+		{
+			"Proto a < b",
+			Port{Proto: "udp", Port: 100, Process: "proc1", inode: "inode1"},
+			Port{Proto: "tcp", Port: 100, Process: "proc1", inode: "inode1"},
+			false,
+		},
+		{
+			"inode a < b",
+			Port{Proto: "tcp", Port: 100, Process: "proc1", inode: "inode1"},
+			Port{Proto: "tcp", Port: 100, Process: "proc1", inode: "inode2"},
+			true,
+		},
+		{
+			"inode a > b",
+			Port{Proto: "tcp", Port: 100, Process: "proc2", inode: "inode2"},
+			Port{Proto: "tcp", Port: 100, Process: "proc1", inode: "inode1"},
+			false,
+		},
+		{
+			"Process a < b",
+			Port{Proto: "tcp", Port: 100, Process: "proc1", inode: "inode1"},
+			Port{Proto: "tcp", Port: 100, Process: "proc2", inode: "inode1"},
+			true,
+		},
+		{
+			"Process a > b",
+			Port{Proto: "tcp", Port: 100, Process: "proc2", inode: "inode1"},
+			Port{Proto: "tcp", Port: 100, Process: "proc1", inode: "inode1"},
+			false,
+		},
+		{
+			"Port evaluated first",
+			Port{Proto: "udp", Port: 100, Process: "proc2", inode: "inode2"},
+			Port{Proto: "tcp", Port: 101, Process: "proc1", inode: "inode1"},
+			true,
+		},
+		{
+			"Proto evaluated second",
+			Port{Proto: "tcp", Port: 100, Process: "proc2", inode: "inode2"},
+			Port{Proto: "udp", Port: 100, Process: "proc1", inode: "inode1"},
+			true,
+		},
+		{
+			"inode evaluated third",
+			Port{Proto: "tcp", Port: 100, Process: "proc2", inode: "inode1"},
+			Port{Proto: "tcp", Port: 100, Process: "proc1", inode: "inode2"},
+			true,
+		},
+		{
+			"Process evaluated fourth",
+			Port{Proto: "tcp", Port: 100, Process: "proc1", inode: "inode1"},
+			Port{Proto: "tcp", Port: 100, Process: "proc2", inode: "inode1"},
+			true,
+		},
+		{
+			"equal",
+			Port{Proto: "tcp", Port: 100, Process: "proc1", inode: "inode1"},
+			Port{Proto: "tcp", Port: 100, Process: "proc1", inode: "inode1"},
+			false,
+		},
+	}
+
+	for _, tt := range tests {
+		got := tt.a.lessThan(&tt.b)
+		if got != tt.want {
+			t.Errorf("%s: Equal = %v; want %v", tt.name, got, tt.want)
+		}
+	}
+}
+
+func TestSameInodes(t *testing.T) {
+	port1 := Port{Proto: "tcp", Port: 100, Process: "proc", inode: "inode1"}
+	port2 := Port{Proto: "tcp", Port: 100, Process: "proc", inode: "inode1"}
+	portProto := Port{Proto: "udp", Port: 100, Process: "proc", inode: "inode1"}
+	portPort := Port{Proto: "tcp", Port: 101, Process: "proc", inode: "inode1"}
+	portInode := Port{Proto: "tcp", Port: 100, Process: "proc", inode: "inode2"}
+	portProcess := Port{Proto: "tcp", Port: 100, Process: "other", inode: "inode1"}
+
+	tests := []struct {
+		name string
+		a, b List
+		want bool
+	}{
+		{
+			"identical",
+			List{port1, port1},
+			List{port2, port2},
+			true,
+		},
+		{
+			"proto differs",
+			List{port1, port1},
+			List{port2, portProto},
+			false,
+		},
+		{
+			"port differs",
+			List{port1, port1},
+			List{port2, portPort},
+			false,
+		},
+		{
+			"inode differs",
+			List{port1, port1},
+			List{port2, portInode},
+			false,
+		},
+		{
+			// SameInodes does not check the Process field
+			"Process differs",
+			List{port1, port1},
+			List{port2, portProcess},
+			true,
+		},
+	}
+	for _, tt := range tests {
+		got := tt.a.SameInodes(tt.b)
+		if got != tt.want {
+			t.Errorf("%s: Equal = %v; want %v", tt.name, got, tt.want)
+		}
+	}
+}
+
 func BenchmarkGetList(b *testing.B) {
 	b.ReportAllocs()
 	for i := 0; i < b.N; i++ {

portlist/portlist_windows.go

@@ -5,11 +5,11 @@
 package portlist
 
 import (
+	"os/exec"
 	"syscall"
 	"time"
 
 	"golang.org/x/sys/windows"
-	exec "tailscale.com/tempfork/osexec"
 )
 
 // Forking on Windows is insanely expensive, so don't do it too often.

safesocket/unixsocket.go

@@ -64,10 +64,33 @@ func listen(path string, port uint16) (ln net.Listener, _ uint16, err error) {
 	if err != nil {
 		return nil, 0, err
 	}
-	os.Chmod(path, 0666)
+	os.Chmod(path, socketPermissionsForOS())
 	return pipe, 0, err
 }
 
+// socketPermissionsForOS returns the permissions to use for the
+// tailscaled.sock.
+func socketPermissionsForOS() os.FileMode {
+	if runtime.GOOS == "linux" {
+		// On Linux, the ipn/ipnserver package looks at the Unix peer creds
+		// and only permits read-only actions from non-root users, so we want
+		// this opened up wider.
+		//
+		// TODO(bradfitz): unify this all one in place probably, moving some
+		// of ipnserver (which does much of the "safe" bits) here. Maybe
+		// instead of net.Listener, we should return a type that returns
+		// an identity in addition to a net.Conn? (returning a wrapped net.Conn
+		// would surprise downstream callers probably)
+		//
+		// TODO(bradfitz): if OpenBSD and FreeBSD do the equivalent peercreds
+		// stuff that's in ipn/ipnserver/conn_ucred.go, they should also
+		// return 0666 here.
+		return 0666
+	}
+	// Otherwise, root only.
+	return 0600
+}
+
 // connectMacOSAppSandbox connects to the Tailscale Network Extension,
 // which is necessarily running within the macOS App Sandbox.  Our
 // little dance to connect a regular user binary to the sandboxed

scripts/check_license_headers.sh

@@ -10,7 +10,7 @@
 check_file() {
     got=$1
 
-    for year in `seq 2019 2020`; do
+    for year in `seq 2019 2021`; do
         want=$(cat <<EOF
 // Copyright (c) $year Tailscale Inc & AUTHORS All rights reserved.
 // Use of this source code is governed by a BSD-style

shell.nix

@@ -0,0 +1,24 @@
+# This is a shell.nix file used to describe the environment that tailscale needs
+# for development. This includes a lot of the basic tools that you need in order
+# to get started. We hope this file will be useful for users of Nix on macOS or
+# Linux.
+#
+# For more information about this and why this file is useful, see here:
+# https://nixos.org/guides/nix-pills/developing-with-nix-shell.html
+#
+# Also look into direnv: https://direnv.net/, this can make it so that you can
+# automatically get your environment set up when you change folders into the
+# project.
+{ pkgs ? import <nixpkgs> {} }:
+
+pkgs.mkShell {
+  # This specifies the tools that are needed for people to get started with
+  # development. These tools include:
+  #  - The Go compiler toolchain (and all additional tooling with it)
+  #  - goimports, a robust formatting tool for Go source code
+  #  - gopls, the language server for Go to increase editor integration
+  #  - git, the version control program (used in some scripts)
+  buildInputs = with pkgs; [
+    go goimports gopls git
+  ];
+}

syncs/syncs.go

@@ -33,7 +33,7 @@ func NewWaitGroupChan() *WaitGroupChan {
 }
 
 // DoneChan returns a channel that's closed on completion.
-func (c *WaitGroupChan) DoneChan() <-chan struct{} { return c.done }
+func (wg *WaitGroupChan) DoneChan() <-chan struct{} { return wg.done }
 
 // Add adds delta, which may be negative, to the WaitGroupChan
 // counter. If the counter becomes zero, all goroutines blocked on
@@ -46,10 +46,10 @@ func (c *WaitGroupChan) DoneChan() <-chan struct{} { return c.done }
 // than zero, may happen at any time. Typically this means the calls
 // to Add should execute before the statement creating the goroutine
 // or other event to be waited for.
-func (c *WaitGroupChan) Add(delta int) {
-	n := atomic.AddInt64(&c.n, int64(delta))
+func (wg *WaitGroupChan) Add(delta int) {
+	n := atomic.AddInt64(&wg.n, int64(delta))
 	if n == 0 {
-		close(c.done)
+		close(wg.done)
 	}
 }
 

tailcfg/tailcfg.go

@@ -14,7 +14,6 @@ import (
 	"strings"
 	"time"
 
-	"github.com/tailscale/wireguard-go/wgcfg"
 	"go4.org/mem"
 	"golang.org/x/oauth2"
 	"inet.af/netaddr"
@@ -23,6 +22,18 @@ import (
 	"tailscale.com/types/structs"
 )
 
+// CurrentMapRequestVersion is the current MapRequest.Version value.
+//
+// History of versions:
+//     3: implicit compression, keep-alives
+//     4: opt-in keep-alives via KeepAlive field, opt-in compression via Compress
+//     5: 2020-10-19, implies IncludeIPv6, delta Peers/UserProfiles, supports MagicDNS
+//     6: 2020-12-07: means MapResponse.PacketFilter nil means unchanged
+//     7: 2020-12-15: FilterRule.SrcIPs accepts CIDRs+ranges, doesn't warn about 0.0.0.0/::
+//     8: 2020-12-19: client can receive IPv6 addresses and routes if beta enabled server-side
+//     9: 2020-12-30: client doesn't auto-add implicit search domains from peers; only DNSConfig.Domains
+const CurrentMapRequestVersion = 9
+
 type ID int64
 
 type UserID ID
@@ -112,8 +123,6 @@ type User struct {
 	Logins        []LoginID
 	Roles         []RoleID
 	Created       time.Time
-
-	// Note: be sure to update Clone when adding new fields
 }
 
 type Login struct {
@@ -138,27 +147,32 @@ type UserProfile struct {
 }
 
 type Node struct {
-	ID         NodeID
-	Name       string // DNS
-	User       UserID
+	ID   NodeID
+	Name string // DNS
+
+	// User is the user who created the node. If ACL tags are in
+	// use for the node then it doesn't reflect the ACL identity
+	// that the node is running as.
+	User UserID
+
+	// Sharer, if non-zero, is the user who shared this node, if different than User.
+	Sharer UserID `json:",omitempty"`
+
 	Key        NodeKey
 	KeyExpiry  time.Time
 	Machine    MachineKey
 	DiscoKey   DiscoKey
-	Addresses  []wgcfg.CIDR // IP addresses of this Node directly
-	AllowedIPs []wgcfg.CIDR // range of IP addresses to route to this node
-	Endpoints  []string     `json:",omitempty"` // IP+port (public via STUN, and local LANs)
-	DERP       string       `json:",omitempty"` // DERP-in-IP:port ("127.3.3.40:N") endpoint
+	Addresses  []netaddr.IPPrefix // IP addresses of this Node directly
+	AllowedIPs []netaddr.IPPrefix // range of IP addresses to route to this node
+	Endpoints  []string           `json:",omitempty"` // IP+port (public via STUN, and local LANs)
+	DERP       string             `json:",omitempty"` // DERP-in-IP:port ("127.3.3.40:N") endpoint
 	Hostinfo   Hostinfo
 	Created    time.Time
 	LastSeen   *time.Time `json:",omitempty"`
 
-	KeepAlive bool // open and keep open a connection to this peer
+	KeepAlive bool `json:",omitempty"` // open and keep open a connection to this peer
 
-	MachineAuthorized bool // TODO(crawshaw): replace with MachineStatus
-
-	// NOTE: any new fields containing pointers in this type
-	//       require changes to Node.Clone.
+	MachineAuthorized bool `json:",omitempty"` // TODO(crawshaw): replace with MachineStatus
 }
 
 type MachineStatus int
@@ -218,7 +232,7 @@ func isAlpha(b byte) bool {
 	return (b >= 'A' && b <= 'Z') || (b >= 'a' && b <= 'z')
 }
 
-// CheckTag valids whether a given string can be used as an ACL tag.
+// CheckTag validates tag for use as an ACL tag.
 // For now we allow only ascii alphanumeric tags, and they need to start
 // with a letter. No unicode shenanigans allowed, and we reserve punctuation
 // marks other than '-' for a possible future URI scheme.
@@ -248,6 +262,19 @@ func CheckTag(tag string) error {
 	return nil
 }
 
+// CheckRequestTags checks that all of h.RequestTags are valid.
+func (h *Hostinfo) CheckRequestTags() error {
+	if h == nil {
+		return nil
+	}
+	for _, tag := range h.RequestTags {
+		if err := CheckTag(tag); err != nil {
+			return fmt.Errorf("tag(%#v): %w", tag, err)
+		}
+	}
+	return nil
+}
+
 type ServiceProto string
 
 const (
@@ -262,9 +289,6 @@ type Service struct {
 	Description string       `json:",omitempty"` // text description of service
 	// TODO(apenwarr): allow advertising services on subnet IPs?
 	// TODO(apenwarr): add "tags" here for each service?
-
-	// NOTE: any new fields containing pointers in this type
-	//       require changes to Hostinfo.Clone.
 }
 
 // Hostinfo contains a summary of a Tailscale host.
@@ -274,21 +298,23 @@ type Service struct {
 type Hostinfo struct {
 	// TODO(crawshaw): mark all these fields ",omitempty" when all the
 	// iOS apps are updated with the latest swift version of this struct.
-	IPNVersion    string       // version of this code
-	FrontendLogID string       `json:",omitempty"` // logtail ID of frontend instance
-	BackendLogID  string       `json:",omitempty"` // logtail ID of backend instance
-	OS            string       // operating system the client runs on (a version.OS value)
-	OSVersion     string       `json:",omitempty"` // operating system version, with optional distro prefix ("Debian 10.4", "Windows 10 Pro 10.0.19041")
-	DeviceModel   string       `json:",omitempty"` // mobile phone model ("Pixel 3a", "iPhone 11 Pro")
-	Hostname      string       // name of the host the client runs on
-	GoArch        string       `json:",omitempty"` // the host's GOARCH value (of the running binary)
-	RoutableIPs   []wgcfg.CIDR `json:",omitempty"` // set of IP ranges this client can route
-	RequestTags   []string     `json:",omitempty"` // set of ACL tags this node wants to claim
-	Services      []Service    `json:",omitempty"` // services advertised by this machine
-	NetInfo       *NetInfo     `json:",omitempty"`
+	IPNVersion    string             `json:",omitempty"` // version of this code
+	FrontendLogID string             `json:",omitempty"` // logtail ID of frontend instance
+	BackendLogID  string             `json:",omitempty"` // logtail ID of backend instance
+	OS            string             // operating system the client runs on (a version.OS value)
+	OSVersion     string             `json:",omitempty"` // operating system version, with optional distro prefix ("Debian 10.4", "Windows 10 Pro 10.0.19041")
+	DeviceModel   string             `json:",omitempty"` // mobile phone model ("Pixel 3a", "iPhone 11 Pro")
+	Hostname      string             // name of the host the client runs on
+	ShieldsUp     bool               `json:",omitempty"` // indicates whether the host is blocking incoming connections
+	ShareeNode    bool               `json:",omitempty"` // indicates this node exists in netmap because it's owned by a shared-to user
+	GoArch        string             `json:",omitempty"` // the host's GOARCH value (of the running binary)
+	RoutableIPs   []netaddr.IPPrefix `json:",omitempty"` // set of IP ranges this client can route
+	RequestTags   []string           `json:",omitempty"` // set of ACL tags this node wants to claim
+	Services      []Service          `json:",omitempty"` // services advertised by this machine
+	NetInfo       *NetInfo           `json:",omitempty"`
 
 	// NOTE: any new fields containing pointers in this type
-	//       require changes to Hostinfo.Clone and Hostinfo.Equal.
+	//       require changes to Hostinfo.Equal.
 }
 
 // NetInfo contains information about the host's network state.
@@ -340,7 +366,7 @@ type NetInfo struct {
 	// the control plane.
 	DERPLatency map[string]float64 `json:",omitempty"`
 
-	// Update Clone and BasicallyEqual when adding fields.
+	// Update BasicallyEqual when adding fields.
 }
 
 func (ni *NetInfo) String() string {
@@ -465,11 +491,9 @@ type MapRequest struct {
 	// we want to signal to the control server that we're capable of something
 	// different.
 	//
-	// History of versions:
-	//     3: implicit compression, keep-alives
-	//     4: opt-in keep-alives via KeepAlive field, opt-in compression via Compress
-	//     5: 2020-10-19, implies IncludeIPv6, DeltaPeers/DeltaUserProfiles, supports MagicDNS
-	Version     int
+	// For current values and history, see CurrentMapRequestVersion above.
+	Version int
+
 	Compress    string // "zstd" or "" (no compression)
 	KeepAlive   bool   // whether server should send keep-alives back to us
 	NodeKey     NodeKey
@@ -491,6 +515,10 @@ type MapRequest struct {
 	// OmitPeers is whether the client is okay with the Peers list
 	// being omitted in the response. (For example, a client on
 	// start up using ReadOnly to get the DERP map.)
+	//
+	// If OmitPeers is true, Stream is false, and ReadOnly is false,
+	// then the server will let clients update their endpoints without
+	// breaking existing long-polling (Stream == true) connections.
 	OmitPeers bool `json:",omitempty"`
 
 	// DebugFlags is a list of strings specifying debugging and
@@ -503,8 +531,8 @@ type MapRequest struct {
 	// Current DebugFlags values are:
 	//     * "warn-ip-forwarding-off": client is trying to be a subnet
 	//       router but their IP forwarding is broken.
-	//     * "v6-overlay": IPv6 development flag to have control send
-	//       v6 node addrs
+	//     * "minimize-netmap": have control minimize the netmap, removing
+	//       peers that are unreachable per ACLS.
 	DebugFlags []string `json:",omitempty"`
 }
 
@@ -516,11 +544,11 @@ type PortRange struct {
 
 var PortRangeAny = PortRange{0, 65535}
 
-// NetPortRange represents a single subnet:portrange.
+// NetPortRange represents a range of ports that's allowed for one or more IPs.
 type NetPortRange struct {
 	_     structs.Incomparable
-	IP    string // "*" means all
-	Bits  *int   // backward compatibility: if missing, means "all" bits
+	IP    string // IP, CIDR, Range, or "*" (same formats as FilterRule.SrcIPs)
+	Bits  *int   // deprecated; the old way to turn IP into a CIDR
 	Ports PortRange
 }
 
@@ -531,19 +559,26 @@ type NetPortRange struct {
 // allowed if a source IP is mathces of those CIDRs.
 type FilterRule struct {
 	// SrcIPs are the source IPs/networks to match.
-	// The special value "*" means to match all.
+	//
+	// It may take the following forms:
+	//     * an IP address (IPv4 or IPv6)
+	//     * the string "*" to match everything (both IPv4 & IPv6)
+	//     * a CIDR (e.g. "192.168.0.0/16")
+	//     * a range of two IPs, inclusive, separated by hyphen ("2eff::1-2eff::0800")
 	SrcIPs []string
 
-	// SrcBits values correspond to the SrcIPs above.
+	// SrcBits is deprecated; it's the old way to specify a CIDR
+	// prior to MapRequest.Version 7. Its values correspond to the
+	// SrcIPs above.
 	//
-	// If present at the same index, it changes the SrcIP above to
-	// be a network with /n CIDR bits. If the slice is nil or
-	// insufficiently long, the default value (for an IPv4
-	// address) for a position is 32, as if the SrcIPs above were
-	// a /32 mask. For a "*" SrcIPs value, the corresponding
-	// SrcBits value is ignored.
-	// TODO: for IPv6, clarify default bits length.
-	SrcBits []int
+	// If an entry of SrcBits is present for the same index as a
+	// SrcIPs entry, it changes the SrcIP above to be a network
+	// with /n CIDR bits. If the slice is nil or insufficiently
+	// long, the default value (for an IPv4 address) for a
+	// position is 32, as if the SrcIPs above were a /32 mask. For
+	// a "*" SrcIPs value, the corresponding SrcBits value is
+	// ignored.
+	SrcBits []int `json:",omitempty"`
 
 	// DstPorts are the port ranges to allow once a source IP
 	// matches (is in the CIDR described by SrcIPs & SrcBits).
@@ -587,14 +622,15 @@ type MapResponse struct {
 
 	// Peers, if non-empty, is the complete list of peers.
 	// It will be set in the first MapResponse for a long-polled request/response.
-	// Subsequent responses will be delta-encoded if DeltaPeers was set in the request.
+	// Subsequent responses will be delta-encoded if MapRequest.Version >= 5 and server
+	// chooses, in which case Peers will be nil or zero length.
 	// If Peers is non-empty, PeersChanged and PeersRemoved should
 	// be ignored (and should be empty).
 	// Peers is always returned sorted by Node.ID.
 	Peers []*Node `json:",omitempty"`
 	// PeersChanged are the Nodes (identified by their ID) that
 	// have changed or been added since the past update on the
-	// HTTP response. It's only set if MapRequest.DeltaPeers was true.
+	// HTTP response. It's not used by the server if MapRequest.Version < 5.
 	// PeersChanged is always returned sorted by Node.ID.
 	PeersChanged []*Node `json:",omitempty"`
 	// PeersRemoved are the NodeIDs that are no longer in the peer list.
@@ -603,18 +639,47 @@ type MapResponse struct {
 	// DNS is the same as DNSConfig.Nameservers.
 	//
 	// TODO(dmytro): should be sent in DNSConfig.Nameservers once clients have updated.
-	DNS []wgcfg.IP `json:",omitempty"`
-	// SearchPaths are the same as DNSConfig.Domains.
-	//
-	// TODO(dmytro): should be sent in DNSConfig.Domains once clients have updated.
-	SearchPaths []string  `json:",omitempty"`
-	DNSConfig   DNSConfig `json:",omitempty"`
+	DNS []netaddr.IP `json:",omitempty"`
 
-	// ACLs
-	Domain       string
+	// SearchPaths is the old way to specify DNS search
+	// domains. Clients should use these values if set, but the
+	// server will omit this field for clients with
+	// MapRequest.Version >= 9. Clients should prefer to use
+	// DNSConfig.Domains instead.
+	SearchPaths []string `json:",omitempty"`
+
+	// DNSConfig contains the DNS settings for the client to use.
+	//
+	// TODO(bradfitz): make this a pointer and conditionally sent
+	// only if changed, like DERPMap, PacketFilter, etc. It's
+	// small, though.
+	DNSConfig DNSConfig `json:",omitempty"`
+
+	// Domain is the name of the network that this node is
+	// in. It's either of the form "example.com" (for user
+	// foo@example.com, for multi-user networks) or
+	// "foo@gmail.com" (for siloed users on shared email
+	// providers). Its exact form should not be depended on; new
+	// forms are coming later.
+	Domain string
+
+	// CollectServices reports whether this node's Tailnet has
+	// requested that info about services be included in HostInfo.
+	// If unset, the most recent non-empty MapResponse value in
+	// the HTTP response stream is used.
+	CollectServices opt.Bool `json:",omitempty"`
+
+	// PacketFilter are the firewall rules.
+	//
+	// For MapRequest.Version >= 6, a nil value means the most
+	// previously streamed non-nil MapResponse.PacketFilter within
+	// the same HTTP response. A non-nil but empty list always means
+	// no PacketFilter (that is, to block everything).
 	PacketFilter []FilterRule
-	UserProfiles []UserProfile // as of 1.1.541: may be new or updated user profiles only
+
+	UserProfiles []UserProfile // as of 1.1.541 (mapver 5): may be new or updated user profiles only
 	Roles        []Role        // deprecated; clients should not rely on Roles
+
 	// TODO: Groups       []Group
 	// TODO: Capabilities []Capability
 
@@ -716,6 +781,7 @@ func (n *Node) Equal(n2 *Node) bool {
 		n.ID == n2.ID &&
 		n.Name == n2.Name &&
 		n.User == n2.User &&
+		n.Sharer == n2.Sharer &&
 		n.Key == n2.Key &&
 		n.KeyExpiry.Equal(n2.KeyExpiry) &&
 		n.Machine == n2.Machine &&
@@ -742,7 +808,7 @@ func eqStrings(a, b []string) bool {
 	return true
 }
 
-func eqCIDRs(a, b []wgcfg.CIDR) bool {
+func eqCIDRs(a, b []netaddr.IPPrefix) bool {
 	if len(a) != len(b) || ((a == nil) != (b == nil)) {
 		return false
 	}

tailcfg/tailcfg_clone.go

@@ -7,7 +7,6 @@
 package tailcfg
 
 import (
-	"github.com/tailscale/wireguard-go/wgcfg"
 	"inet.af/netaddr"
 	"tailscale.com/types/opt"
 	"tailscale.com/types/structs"
@@ -65,12 +64,13 @@ var _NodeNeedsRegeneration = Node(struct {
 	ID                NodeID
 	Name              string
 	User              UserID
+	Sharer            UserID
 	Key               NodeKey
 	KeyExpiry         time.Time
 	Machine           MachineKey
 	DiscoKey          DiscoKey
-	Addresses         []wgcfg.CIDR
-	AllowedIPs        []wgcfg.CIDR
+	Addresses         []netaddr.IPPrefix
+	AllowedIPs        []netaddr.IPPrefix
 	Endpoints         []string
 	DERP              string
 	Hostinfo          Hostinfo
@@ -105,8 +105,10 @@ var _HostinfoNeedsRegeneration = Hostinfo(struct {
 	OSVersion     string
 	DeviceModel   string
 	Hostname      string
+	ShieldsUp     bool
+	ShareeNode    bool
 	GoArch        string
-	RoutableIPs   []wgcfg.CIDR
+	RoutableIPs   []netaddr.IPPrefix
 	RequestTags   []string
 	Services      []Service
 	NetInfo       *NetInfo

tailcfg/tailcfg_test.go

@@ -11,7 +11,8 @@ import (
 	"testing"
 	"time"
 
-	"github.com/tailscale/wireguard-go/wgcfg"
+	"inet.af/netaddr"
+	"tailscale.com/types/wgkey"
 )
 
 func fieldsOf(t reflect.Type) (fields []string) {
@@ -23,18 +24,21 @@ func fieldsOf(t reflect.Type) (fields []string) {
 
 func TestHostinfoEqual(t *testing.T) {
 	hiHandles := []string{
-		"IPNVersion", "FrontendLogID", "BackendLogID", "OS", "OSVersion",
-		"DeviceModel", "Hostname", "GoArch", "RoutableIPs", "RequestTags", "Services",
-		"NetInfo",
+		"IPNVersion", "FrontendLogID", "BackendLogID",
+		"OS", "OSVersion", "DeviceModel", "Hostname",
+		"ShieldsUp", "ShareeNode",
+		"GoArch",
+		"RoutableIPs", "RequestTags",
+		"Services", "NetInfo",
 	}
 	if have := fieldsOf(reflect.TypeOf(Hostinfo{})); !reflect.DeepEqual(have, hiHandles) {
 		t.Errorf("Hostinfo.Equal check might be out of sync\nfields: %q\nhandled: %q\n",
 			have, hiHandles)
 	}
 
-	nets := func(strs ...string) (ns []wgcfg.CIDR) {
+	nets := func(strs ...string) (ns []netaddr.IPPrefix) {
 		for _, s := range strs {
-			n, err := wgcfg.ParseCIDR(s)
+			n, err := netaddr.ParseIPPrefix(s)
 			if err != nil {
 				panic(err)
 			}
@@ -169,6 +173,11 @@ func TestHostinfoEqual(t *testing.T) {
 			&Hostinfo{Services: []Service{Service{Proto: TCP, Port: 1234, Description: "foo"}}},
 			true,
 		},
+		{
+			&Hostinfo{ShareeNode: true},
+			&Hostinfo{},
+			false,
+		},
 	}
 	for i, tt := range tests {
 		got := tt.a.Equal(tt.b)
@@ -179,15 +188,20 @@ func TestHostinfoEqual(t *testing.T) {
 }
 
 func TestNodeEqual(t *testing.T) {
-	nodeHandles := []string{"ID", "Name", "User", "Key", "KeyExpiry", "Machine", "DiscoKey", "Addresses", "AllowedIPs", "Endpoints", "DERP", "Hostinfo", "Created", "LastSeen", "KeepAlive", "MachineAuthorized"}
+	nodeHandles := []string{
+		"ID", "Name", "User", "Sharer",
+		"Key", "KeyExpiry", "Machine", "DiscoKey",
+		"Addresses", "AllowedIPs", "Endpoints", "DERP", "Hostinfo",
+		"Created", "LastSeen", "KeepAlive", "MachineAuthorized",
+	}
 	if have := fieldsOf(reflect.TypeOf(Node{})); !reflect.DeepEqual(have, nodeHandles) {
 		t.Errorf("Node.Equal check might be out of sync\nfields: %q\nhandled: %q\n",
 			have, nodeHandles)
 	}
 
-	newPublicKey := func(t *testing.T) wgcfg.Key {
+	newPublicKey := func(t *testing.T) wgkey.Key {
 		t.Helper()
-		k, err := wgcfg.NewPrivateKey()
+		k, err := wgkey.NewPrivate()
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -256,23 +270,23 @@ func TestNodeEqual(t *testing.T) {
 			true,
 		},
 		{
-			&Node{Addresses: []wgcfg.CIDR{}},
+			&Node{Addresses: []netaddr.IPPrefix{}},
 			&Node{Addresses: nil},
 			false,
 		},
 		{
-			&Node{Addresses: []wgcfg.CIDR{}},
-			&Node{Addresses: []wgcfg.CIDR{}},
+			&Node{Addresses: []netaddr.IPPrefix{}},
+			&Node{Addresses: []netaddr.IPPrefix{}},
 			true,
 		},
 		{
-			&Node{AllowedIPs: []wgcfg.CIDR{}},
+			&Node{AllowedIPs: []netaddr.IPPrefix{}},
 			&Node{AllowedIPs: nil},
 			false,
 		},
 		{
-			&Node{Addresses: []wgcfg.CIDR{}},
-			&Node{Addresses: []wgcfg.CIDR{}},
+			&Node{Addresses: []netaddr.IPPrefix{}},
+			&Node{Addresses: []netaddr.IPPrefix{}},
 			true,
 		},
 		{
@@ -421,8 +435,8 @@ func TestCloneNode(t *testing.T) {
 	}{
 		{"nil_fields", &Node{}},
 		{"zero_fields", &Node{
-			Addresses:  make([]wgcfg.CIDR, 0),
-			AllowedIPs: make([]wgcfg.CIDR, 0),
+			Addresses:  make([]netaddr.IPPrefix, 0),
+			AllowedIPs: make([]netaddr.IPPrefix, 0),
 			Endpoints:  make([]string, 0),
 		}},
 	}

tempfork/osexec/README.md

@@ -1,47 +0,0 @@
-This is a temporary fork of Go 1.13's os/exec package,
-to work around https://github.com/golang/go/issues/36644.
-
-The main modification (outside of removing some tests that require
-internal-only packages to run) is:
-
-```
-commit 3c66be240f1ee1f1b5f03bed79eb0d9f8c08965a
-Author: Avery Pennarun <apenwarr@gmail.com>
-Date:   Sun Jan 19 03:17:30 2020 -0500
-
-Cmd.Wait(): handle EINTR return code from os.Process.Wait().
-
-This is probably not actually the correct fix; most likely
-os.Process.Wait() itself should be fixed to retry on EINTR so that it
-never leaks out of that function. But if we're going to patch a
-particular module, it's safer to patch a higher-level one like os/exec
-rather than the os module itself.
-
-diff --git a/exec.go b/exec.go
-index 17ef003e..5375e673 100644
---- a/exec.go
-+++ b/exec.go
-@@ -498,7 +498,21 @@ func (c *Cmd) Wait() error {
-        }
-                c.finished = true
-
--       state, err := c.Process.Wait()
-+       var err error
-+       var state *os.ProcessState
-+       for {
-+               state, err = c.Process.Wait()
-+               if err != nil {
-+                       xe, ok := err.(*os.SyscallError)
-+                       if ok {
-+                               if xe.Unwrap() == syscall.EINTR {
-+                                       // temporary error, retry wait syscall
-+                                       continue
-+                               }
-+                       }
-+               }
-+               break
-+       }
-        if c.waitDone != nil {
-                        close(c.waitDone)
-                                }
-```

tempfork/osexec/bench_test.go

@@ -1,23 +0,0 @@
-// Copyright 2019 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package exec
-
-import (
-	"testing"
-)
-
-func BenchmarkExecHostname(b *testing.B) {
-	b.ReportAllocs()
-	path, err := LookPath("hostname")
-	if err != nil {
-		b.Fatalf("could not find hostname: %v", err)
-	}
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
-		if err := Command(path).Run(); err != nil {
-			b.Fatalf("hostname: %v", err)
-		}
-	}
-}

tempfork/osexec/env_test.go

@@ -1,39 +0,0 @@
-// Copyright 2017 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package exec
-
-import (
-	"reflect"
-	"testing"
-)
-
-func TestDedupEnv(t *testing.T) {
-	tests := []struct {
-		noCase bool
-		in     []string
-		want   []string
-	}{
-		{
-			noCase: true,
-			in:     []string{"k1=v1", "k2=v2", "K1=v3"},
-			want:   []string{"K1=v3", "k2=v2"},
-		},
-		{
-			noCase: false,
-			in:     []string{"k1=v1", "K1=V2", "k1=v3"},
-			want:   []string{"k1=v3", "K1=V2"},
-		},
-		{
-			in:   []string{"=a", "=b", "foo", "bar"},
-			want: []string{"=b", "foo", "bar"},
-		},
-	}
-	for _, tt := range tests {
-		got := dedupEnvCase(tt.noCase, tt.in)
-		if !reflect.DeepEqual(got, tt.want) {
-			t.Errorf("Dedup(%v, %q) = %q; want %q", tt.noCase, tt.in, got, tt.want)
-		}
-	}
-}

tempfork/osexec/example_test.go

@@ -1,156 +0,0 @@
-// Copyright 2012 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package exec_test
-
-import (
-	"bytes"
-	"context"
-	"encoding/json"
-	"fmt"
-	"io"
-	"io/ioutil"
-	"log"
-	"os"
-	"os/exec"
-	"strings"
-	"time"
-)
-
-func ExampleLookPath() {
-	path, err := exec.LookPath("fortune")
-	if err != nil {
-		log.Fatal("installing fortune is in your future")
-	}
-	fmt.Printf("fortune is available at %s\n", path)
-}
-
-func ExampleCommand() {
-	cmd := exec.Command("tr", "a-z", "A-Z")
-	cmd.Stdin = strings.NewReader("some input")
-	var out bytes.Buffer
-	cmd.Stdout = &out
-	err := cmd.Run()
-	if err != nil {
-		log.Fatal(err)
-	}
-	fmt.Printf("in all caps: %q\n", out.String())
-}
-
-func ExampleCommand_environment() {
-	cmd := exec.Command("prog")
-	cmd.Env = append(os.Environ(),
-		"FOO=duplicate_value", // ignored
-		"FOO=actual_value",    // this value is used
-	)
-	if err := cmd.Run(); err != nil {
-		log.Fatal(err)
-	}
-}
-
-func ExampleCmd_Output() {
-	out, err := exec.Command("date").Output()
-	if err != nil {
-		log.Fatal(err)
-	}
-	fmt.Printf("The date is %s\n", out)
-}
-
-func ExampleCmd_Run() {
-	cmd := exec.Command("sleep", "1")
-	log.Printf("Running command and waiting for it to finish...")
-	err := cmd.Run()
-	log.Printf("Command finished with error: %v", err)
-}
-
-func ExampleCmd_Start() {
-	cmd := exec.Command("sleep", "5")
-	err := cmd.Start()
-	if err != nil {
-		log.Fatal(err)
-	}
-	log.Printf("Waiting for command to finish...")
-	err = cmd.Wait()
-	log.Printf("Command finished with error: %v", err)
-}
-
-func ExampleCmd_StdoutPipe() {
-	cmd := exec.Command("echo", "-n", `{"Name": "Bob", "Age": 32}`)
-	stdout, err := cmd.StdoutPipe()
-	if err != nil {
-		log.Fatal(err)
-	}
-	if err := cmd.Start(); err != nil {
-		log.Fatal(err)
-	}
-	var person struct {
-		Name string
-		Age  int
-	}
-	if err := json.NewDecoder(stdout).Decode(&person); err != nil {
-		log.Fatal(err)
-	}
-	if err := cmd.Wait(); err != nil {
-		log.Fatal(err)
-	}
-	fmt.Printf("%s is %d years old\n", person.Name, person.Age)
-}
-
-func ExampleCmd_StdinPipe() {
-	cmd := exec.Command("cat")
-	stdin, err := cmd.StdinPipe()
-	if err != nil {
-		log.Fatal(err)
-	}
-
-	go func() {
-		defer stdin.Close()
-		io.WriteString(stdin, "values written to stdin are passed to cmd's standard input")
-	}()
-
-	out, err := cmd.CombinedOutput()
-	if err != nil {
-		log.Fatal(err)
-	}
-
-	fmt.Printf("%s\n", out)
-}
-
-func ExampleCmd_StderrPipe() {
-	cmd := exec.Command("sh", "-c", "echo stdout; echo 1>&2 stderr")
-	stderr, err := cmd.StderrPipe()
-	if err != nil {
-		log.Fatal(err)
-	}
-
-	if err := cmd.Start(); err != nil {
-		log.Fatal(err)
-	}
-
-	slurp, _ := ioutil.ReadAll(stderr)
-	fmt.Printf("%s\n", slurp)
-
-	if err := cmd.Wait(); err != nil {
-		log.Fatal(err)
-	}
-}
-
-func ExampleCmd_CombinedOutput() {
-	cmd := exec.Command("sh", "-c", "echo stdout; echo 1>&2 stderr")
-	stdoutStderr, err := cmd.CombinedOutput()
-	if err != nil {
-		log.Fatal(err)
-	}
-	fmt.Printf("%s\n", stdoutStderr)
-}
-
-func ExampleCommandContext() {
-	ctx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)
-	defer cancel()
-
-	if err := exec.CommandContext(ctx, "sleep", "5").Run(); err != nil {
-		// This will fail after 100 milliseconds. The 5 second sleep
-		// will be interrupted.
-	}
-}

tempfork/osexec/exec.go

@@ -1,797 +0,0 @@
-// Copyright 2009 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// Package exec runs external commands. It wraps os.StartProcess to make it
-// easier to remap stdin and stdout, connect I/O with pipes, and do other
-// adjustments.
-//
-// Unlike the "system" library call from C and other languages, the
-// os/exec package intentionally does not invoke the system shell and
-// does not expand any glob patterns or handle other expansions,
-// pipelines, or redirections typically done by shells. The package
-// behaves more like C's "exec" family of functions. To expand glob
-// patterns, either call the shell directly, taking care to escape any
-// dangerous input, or use the path/filepath package's Glob function.
-// To expand environment variables, use package os's ExpandEnv.
-//
-// Note that the examples in this package assume a Unix system.
-// They may not run on Windows, and they do not run in the Go Playground
-// used by golang.org and godoc.org.
-package exec
-
-import (
-	"bytes"
-	"context"
-	"errors"
-	"io"
-	"os"
-	"path/filepath"
-	"runtime"
-	"strconv"
-	"strings"
-	"sync"
-	"syscall"
-)
-
-// Error is returned by LookPath when it fails to classify a file as an
-// executable.
-type Error struct {
-	// Name is the file name for which the error occurred.
-	Name string
-	// Err is the underlying error.
-	Err error
-}
-
-func (e *Error) Error() string {
-	return "exec: " + strconv.Quote(e.Name) + ": " + e.Err.Error()
-}
-
-func (e *Error) Unwrap() error { return e.Err }
-
-// Cmd represents an external command being prepared or run.
-//
-// A Cmd cannot be reused after calling its Run, Output or CombinedOutput
-// methods.
-type Cmd struct {
-	// Path is the path of the command to run.
-	//
-	// This is the only field that must be set to a non-zero
-	// value. If Path is relative, it is evaluated relative
-	// to Dir.
-	Path string
-
-	// Args holds command line arguments, including the command as Args[0].
-	// If the Args field is empty or nil, Run uses {Path}.
-	//
-	// In typical use, both Path and Args are set by calling Command.
-	Args []string
-
-	// Env specifies the environment of the process.
-	// Each entry is of the form "key=value".
-	// If Env is nil, the new process uses the current process's
-	// environment.
-	// If Env contains duplicate environment keys, only the last
-	// value in the slice for each duplicate key is used.
-	// As a special case on Windows, SYSTEMROOT is always added if
-	// missing and not explicitly set to the empty string.
-	Env []string
-
-	// Dir specifies the working directory of the command.
-	// If Dir is the empty string, Run runs the command in the
-	// calling process's current directory.
-	Dir string
-
-	// Stdin specifies the process's standard input.
-	//
-	// If Stdin is nil, the process reads from the null device (os.DevNull).
-	//
-	// If Stdin is an *os.File, the process's standard input is connected
-	// directly to that file.
-	//
-	// Otherwise, during the execution of the command a separate
-	// goroutine reads from Stdin and delivers that data to the command
-	// over a pipe. In this case, Wait does not complete until the goroutine
-	// stops copying, either because it has reached the end of Stdin
-	// (EOF or a read error) or because writing to the pipe returned an error.
-	Stdin io.Reader
-
-	// Stdout and Stderr specify the process's standard output and error.
-	//
-	// If either is nil, Run connects the corresponding file descriptor
-	// to the null device (os.DevNull).
-	//
-	// If either is an *os.File, the corresponding output from the process
-	// is connected directly to that file.
-	//
-	// Otherwise, during the execution of the command a separate goroutine
-	// reads from the process over a pipe and delivers that data to the
-	// corresponding Writer. In this case, Wait does not complete until the
-	// goroutine reaches EOF or encounters an error.
-	//
-	// If Stdout and Stderr are the same writer, and have a type that can
-	// be compared with ==, at most one goroutine at a time will call Write.
-	Stdout io.Writer
-	Stderr io.Writer
-
-	// ExtraFiles specifies additional open files to be inherited by the
-	// new process. It does not include standard input, standard output, or
-	// standard error. If non-nil, entry i becomes file descriptor 3+i.
-	//
-	// ExtraFiles is not supported on Windows.
-	ExtraFiles []*os.File
-
-	// SysProcAttr holds optional, operating system-specific attributes.
-	// Run passes it to os.StartProcess as the os.ProcAttr's Sys field.
-	SysProcAttr *syscall.SysProcAttr
-
-	// Process is the underlying process, once started.
-	Process *os.Process
-
-	// ProcessState contains information about an exited process,
-	// available after a call to Wait or Run.
-	ProcessState *os.ProcessState
-
-	ctx             context.Context // nil means none
-	lookPathErr     error           // LookPath error, if any.
-	finished        bool            // when Wait was called
-	childFiles      []*os.File
-	closeAfterStart []io.Closer
-	closeAfterWait  []io.Closer
-	goroutine       []func() error
-	errch           chan error // one send per goroutine
-	waitDone        chan struct{}
-}
-
-// Command returns the Cmd struct to execute the named program with
-// the given arguments.
-//
-// It sets only the Path and Args in the returned structure.
-//
-// If name contains no path separators, Command uses LookPath to
-// resolve name to a complete path if possible. Otherwise it uses name
-// directly as Path.
-//
-// The returned Cmd's Args field is constructed from the command name
-// followed by the elements of arg, so arg should not include the
-// command name itself. For example, Command("echo", "hello").
-// Args[0] is always name, not the possibly resolved Path.
-//
-// On Windows, processes receive the whole command line as a single string
-// and do their own parsing. Command combines and quotes Args into a command
-// line string with an algorithm compatible with applications using
-// CommandLineToArgvW (which is the most common way). Notable exceptions are
-// msiexec.exe and cmd.exe (and thus, all batch files), which have a different
-// unquoting algorithm. In these or other similar cases, you can do the
-// quoting yourself and provide the full command line in SysProcAttr.CmdLine,
-// leaving Args empty.
-func Command(name string, arg ...string) *Cmd {
-	cmd := &Cmd{
-		Path: name,
-		Args: append([]string{name}, arg...),
-	}
-	if filepath.Base(name) == name {
-		if lp, err := LookPath(name); err != nil {
-			cmd.lookPathErr = err
-		} else {
-			cmd.Path = lp
-		}
-	}
-	return cmd
-}
-
-// CommandContext is like Command but includes a context.
-//
-// The provided context is used to kill the process (by calling
-// os.Process.Kill) if the context becomes done before the command
-// completes on its own.
-func CommandContext(ctx context.Context, name string, arg ...string) *Cmd {
-	if ctx == nil {
-		panic("nil Context")
-	}
-	cmd := Command(name, arg...)
-	cmd.ctx = ctx
-	return cmd
-}
-
-// String returns a human-readable description of c.
-// It is intended only for debugging.
-// In particular, it is not suitable for use as input to a shell.
-// The output of String may vary across Go releases.
-func (c *Cmd) String() string {
-	if c.lookPathErr != nil {
-		// failed to resolve path; report the original requested path (plus args)
-		return strings.Join(c.Args, " ")
-	}
-	// report the exact executable path (plus args)
-	b := new(strings.Builder)
-	b.WriteString(c.Path)
-	for _, a := range c.Args[1:] {
-		b.WriteByte(' ')
-		b.WriteString(a)
-	}
-	return b.String()
-}
-
-// interfaceEqual protects against panics from doing equality tests on
-// two interfaces with non-comparable underlying types.
-func interfaceEqual(a, b interface{}) bool {
-	defer func() {
-		recover()
-	}()
-	return a == b
-}
-
-func (c *Cmd) envv() []string {
-	if c.Env != nil {
-		return c.Env
-	}
-	return os.Environ()
-}
-
-func (c *Cmd) argv() []string {
-	if len(c.Args) > 0 {
-		return c.Args
-	}
-	return []string{c.Path}
-}
-
-// skipStdinCopyError optionally specifies a function which reports
-// whether the provided stdin copy error should be ignored.
-// It is non-nil everywhere but Plan 9, which lacks EPIPE. See exec_posix.go.
-var skipStdinCopyError func(error) bool
-
-func (c *Cmd) stdin() (f *os.File, err error) {
-	if c.Stdin == nil {
-		f, err = os.Open(os.DevNull)
-		if err != nil {
-			return
-		}
-		c.closeAfterStart = append(c.closeAfterStart, f)
-		return
-	}
-
-	if f, ok := c.Stdin.(*os.File); ok {
-		return f, nil
-	}
-
-	pr, pw, err := os.Pipe()
-	if err != nil {
-		return
-	}
-
-	c.closeAfterStart = append(c.closeAfterStart, pr)
-	c.closeAfterWait = append(c.closeAfterWait, pw)
-	c.goroutine = append(c.goroutine, func() error {
-		_, err := io.Copy(pw, c.Stdin)
-		if skip := skipStdinCopyError; skip != nil && skip(err) {
-			err = nil
-		}
-		if err1 := pw.Close(); err == nil {
-			err = err1
-		}
-		return err
-	})
-	return pr, nil
-}
-
-func (c *Cmd) stdout() (f *os.File, err error) {
-	return c.writerDescriptor(c.Stdout)
-}
-
-func (c *Cmd) stderr() (f *os.File, err error) {
-	if c.Stderr != nil && interfaceEqual(c.Stderr, c.Stdout) {
-		return c.childFiles[1], nil
-	}
-	return c.writerDescriptor(c.Stderr)
-}
-
-func (c *Cmd) writerDescriptor(w io.Writer) (f *os.File, err error) {
-	if w == nil {
-		f, err = os.OpenFile(os.DevNull, os.O_WRONLY, 0)
-		if err != nil {
-			return
-		}
-		c.closeAfterStart = append(c.closeAfterStart, f)
-		return
-	}
-
-	if f, ok := w.(*os.File); ok {
-		return f, nil
-	}
-
-	pr, pw, err := os.Pipe()
-	if err != nil {
-		return
-	}
-
-	c.closeAfterStart = append(c.closeAfterStart, pw)
-	c.closeAfterWait = append(c.closeAfterWait, pr)
-	c.goroutine = append(c.goroutine, func() error {
-		_, err := io.Copy(w, pr)
-		pr.Close() // in case io.Copy stopped due to write error
-		return err
-	})
-	return pw, nil
-}
-
-func (c *Cmd) closeDescriptors(closers []io.Closer) {
-	for _, fd := range closers {
-		fd.Close()
-	}
-}
-
-// Run starts the specified command and waits for it to complete.
-//
-// The returned error is nil if the command runs, has no problems
-// copying stdin, stdout, and stderr, and exits with a zero exit
-// status.
-//
-// If the command starts but does not complete successfully, the error is of
-// type *ExitError. Other error types may be returned for other situations.
-//
-// If the calling goroutine has locked the operating system thread
-// with runtime.LockOSThread and modified any inheritable OS-level
-// thread state (for example, Linux or Plan 9 name spaces), the new
-// process will inherit the caller's thread state.
-func (c *Cmd) Run() error {
-	if err := c.Start(); err != nil {
-		return err
-	}
-	return c.Wait()
-}
-
-// lookExtensions finds windows executable by its dir and path.
-// It uses LookPath to try appropriate extensions.
-// lookExtensions does not search PATH, instead it converts `prog` into `.\prog`.
-func lookExtensions(path, dir string) (string, error) {
-	if filepath.Base(path) == path {
-		path = filepath.Join(".", path)
-	}
-	if dir == "" {
-		return LookPath(path)
-	}
-	if filepath.VolumeName(path) != "" {
-		return LookPath(path)
-	}
-	if len(path) > 1 && os.IsPathSeparator(path[0]) {
-		return LookPath(path)
-	}
-	dirandpath := filepath.Join(dir, path)
-	// We assume that LookPath will only add file extension.
-	lp, err := LookPath(dirandpath)
-	if err != nil {
-		return "", err
-	}
-	ext := strings.TrimPrefix(lp, dirandpath)
-	return path + ext, nil
-}
-
-// Start starts the specified command but does not wait for it to complete.
-//
-// The Wait method will return the exit code and release associated resources
-// once the command exits.
-func (c *Cmd) Start() error {
-	if c.lookPathErr != nil {
-		c.closeDescriptors(c.closeAfterStart)
-		c.closeDescriptors(c.closeAfterWait)
-		return c.lookPathErr
-	}
-	if runtime.GOOS == "windows" {
-		lp, err := lookExtensions(c.Path, c.Dir)
-		if err != nil {
-			c.closeDescriptors(c.closeAfterStart)
-			c.closeDescriptors(c.closeAfterWait)
-			return err
-		}
-		c.Path = lp
-	}
-	if c.Process != nil {
-		return errors.New("exec: already started")
-	}
-	if c.ctx != nil {
-		select {
-		case <-c.ctx.Done():
-			c.closeDescriptors(c.closeAfterStart)
-			c.closeDescriptors(c.closeAfterWait)
-			return c.ctx.Err()
-		default:
-		}
-	}
-
-	c.childFiles = make([]*os.File, 0, 3+len(c.ExtraFiles))
-	type F func(*Cmd) (*os.File, error)
-	for _, setupFd := range []F{(*Cmd).stdin, (*Cmd).stdout, (*Cmd).stderr} {
-		fd, err := setupFd(c)
-		if err != nil {
-			c.closeDescriptors(c.closeAfterStart)
-			c.closeDescriptors(c.closeAfterWait)
-			return err
-		}
-		c.childFiles = append(c.childFiles, fd)
-	}
-	c.childFiles = append(c.childFiles, c.ExtraFiles...)
-
-	var err error
-	c.Process, err = os.StartProcess(c.Path, c.argv(), &os.ProcAttr{
-		Dir:   c.Dir,
-		Files: c.childFiles,
-		Env:   addCriticalEnv(dedupEnv(c.envv())),
-		Sys:   c.SysProcAttr,
-	})
-	if err != nil {
-		c.closeDescriptors(c.closeAfterStart)
-		c.closeDescriptors(c.closeAfterWait)
-		return err
-	}
-
-	c.closeDescriptors(c.closeAfterStart)
-
-	// Don't allocate the channel unless there are goroutines to fire.
-	if len(c.goroutine) > 0 {
-		c.errch = make(chan error, len(c.goroutine))
-		for _, fn := range c.goroutine {
-			go func(fn func() error) {
-				c.errch <- fn()
-			}(fn)
-		}
-	}
-
-	if c.ctx != nil {
-		c.waitDone = make(chan struct{})
-		go func() {
-			select {
-			case <-c.ctx.Done():
-				c.Process.Kill()
-			case <-c.waitDone:
-			}
-		}()
-	}
-
-	return nil
-}
-
-// An ExitError reports an unsuccessful exit by a command.
-type ExitError struct {
-	*os.ProcessState
-
-	// Stderr holds a subset of the standard error output from the
-	// Cmd.Output method if standard error was not otherwise being
-	// collected.
-	//
-	// If the error output is long, Stderr may contain only a prefix
-	// and suffix of the output, with the middle replaced with
-	// text about the number of omitted bytes.
-	//
-	// Stderr is provided for debugging, for inclusion in error messages.
-	// Users with other needs should redirect Cmd.Stderr as needed.
-	Stderr []byte
-}
-
-func (e *ExitError) Error() string {
-	return e.ProcessState.String()
-}
-
-// Wait waits for the command to exit and waits for any copying to
-// stdin or copying from stdout or stderr to complete.
-//
-// The command must have been started by Start.
-//
-// The returned error is nil if the command runs, has no problems
-// copying stdin, stdout, and stderr, and exits with a zero exit
-// status.
-//
-// If the command fails to run or doesn't complete successfully, the
-// error is of type *ExitError. Other error types may be
-// returned for I/O problems.
-//
-// If any of c.Stdin, c.Stdout or c.Stderr are not an *os.File, Wait also waits
-// for the respective I/O loop copying to or from the process to complete.
-//
-// Wait releases any resources associated with the Cmd.
-func (c *Cmd) Wait() error {
-	if c.Process == nil {
-		return errors.New("exec: not started")
-	}
-	if c.finished {
-		return errors.New("exec: Wait was already called")
-	}
-	c.finished = true
-
-	var err error
-	var state *os.ProcessState
-	for {
-		state, err = c.Process.Wait()
-		if err != nil {
-			xe, ok := err.(*os.SyscallError)
-			if ok {
-				if xe.Unwrap() == syscall.EINTR {
-					// temporary error, retry wait syscall
-					continue
-				}
-			}
-		}
-		break
-	}
-	if c.waitDone != nil {
-		close(c.waitDone)
-	}
-	c.ProcessState = state
-
-	var copyError error
-	for range c.goroutine {
-		if err := <-c.errch; err != nil && copyError == nil {
-			copyError = err
-		}
-	}
-
-	c.closeDescriptors(c.closeAfterWait)
-
-	if err != nil {
-		return err
-	} else if !state.Success() {
-		return &ExitError{ProcessState: state}
-	}
-
-	return copyError
-}
-
-// Output runs the command and returns its standard output.
-// Any returned error will usually be of type *ExitError.
-// If c.Stderr was nil, Output populates ExitError.Stderr.
-func (c *Cmd) Output() ([]byte, error) {
-	if c.Stdout != nil {
-		return nil, errors.New("exec: Stdout already set")
-	}
-	var stdout bytes.Buffer
-	c.Stdout = &stdout
-
-	captureErr := c.Stderr == nil
-	if captureErr {
-		c.Stderr = &prefixSuffixSaver{N: 32 << 10}
-	}
-
-	err := c.Run()
-	if err != nil && captureErr {
-		if ee, ok := err.(*ExitError); ok {
-			ee.Stderr = c.Stderr.(*prefixSuffixSaver).Bytes()
-		}
-	}
-	return stdout.Bytes(), err
-}
-
-// CombinedOutput runs the command and returns its combined standard
-// output and standard error.
-func (c *Cmd) CombinedOutput() ([]byte, error) {
-	if c.Stdout != nil {
-		return nil, errors.New("exec: Stdout already set")
-	}
-	if c.Stderr != nil {
-		return nil, errors.New("exec: Stderr already set")
-	}
-	var b bytes.Buffer
-	c.Stdout = &b
-	c.Stderr = &b
-	err := c.Run()
-	return b.Bytes(), err
-}
-
-// StdinPipe returns a pipe that will be connected to the command's
-// standard input when the command starts.
-// The pipe will be closed automatically after Wait sees the command exit.
-// A caller need only call Close to force the pipe to close sooner.
-// For example, if the command being run will not exit until standard input
-// is closed, the caller must close the pipe.
-func (c *Cmd) StdinPipe() (io.WriteCloser, error) {
-	if c.Stdin != nil {
-		return nil, errors.New("exec: Stdin already set")
-	}
-	if c.Process != nil {
-		return nil, errors.New("exec: StdinPipe after process started")
-	}
-	pr, pw, err := os.Pipe()
-	if err != nil {
-		return nil, err
-	}
-	c.Stdin = pr
-	c.closeAfterStart = append(c.closeAfterStart, pr)
-	wc := &closeOnce{File: pw}
-	c.closeAfterWait = append(c.closeAfterWait, wc)
-	return wc, nil
-}
-
-type closeOnce struct {
-	*os.File
-
-	once sync.Once
-	err  error
-}
-
-func (c *closeOnce) Close() error {
-	c.once.Do(c.close)
-	return c.err
-}
-
-func (c *closeOnce) close() {
-	c.err = c.File.Close()
-}
-
-// StdoutPipe returns a pipe that will be connected to the command's
-// standard output when the command starts.
-//
-// Wait will close the pipe after seeing the command exit, so most callers
-// need not close the pipe themselves; however, an implication is that
-// it is incorrect to call Wait before all reads from the pipe have completed.
-// For the same reason, it is incorrect to call Run when using StdoutPipe.
-// See the example for idiomatic usage.
-func (c *Cmd) StdoutPipe() (io.ReadCloser, error) {
-	if c.Stdout != nil {
-		return nil, errors.New("exec: Stdout already set")
-	}
-	if c.Process != nil {
-		return nil, errors.New("exec: StdoutPipe after process started")
-	}
-	pr, pw, err := os.Pipe()
-	if err != nil {
-		return nil, err
-	}
-	c.Stdout = pw
-	c.closeAfterStart = append(c.closeAfterStart, pw)
-	c.closeAfterWait = append(c.closeAfterWait, pr)
-	return pr, nil
-}
-
-// StderrPipe returns a pipe that will be connected to the command's
-// standard error when the command starts.
-//
-// Wait will close the pipe after seeing the command exit, so most callers
-// need not close the pipe themselves; however, an implication is that
-// it is incorrect to call Wait before all reads from the pipe have completed.
-// For the same reason, it is incorrect to use Run when using StderrPipe.
-// See the StdoutPipe example for idiomatic usage.
-func (c *Cmd) StderrPipe() (io.ReadCloser, error) {
-	if c.Stderr != nil {
-		return nil, errors.New("exec: Stderr already set")
-	}
-	if c.Process != nil {
-		return nil, errors.New("exec: StderrPipe after process started")
-	}
-	pr, pw, err := os.Pipe()
-	if err != nil {
-		return nil, err
-	}
-	c.Stderr = pw
-	c.closeAfterStart = append(c.closeAfterStart, pw)
-	c.closeAfterWait = append(c.closeAfterWait, pr)
-	return pr, nil
-}
-
-// prefixSuffixSaver is an io.Writer which retains the first N bytes
-// and the last N bytes written to it. The Bytes() methods reconstructs
-// it with a pretty error message.
-type prefixSuffixSaver struct {
-	N         int // max size of prefix or suffix
-	prefix    []byte
-	suffix    []byte // ring buffer once len(suffix) == N
-	suffixOff int    // offset to write into suffix
-	skipped   int64
-
-	// TODO(bradfitz): we could keep one large []byte and use part of it for
-	// the prefix, reserve space for the '... Omitting N bytes ...' message,
-	// then the ring buffer suffix, and just rearrange the ring buffer
-	// suffix when Bytes() is called, but it doesn't seem worth it for
-	// now just for error messages. It's only ~64KB anyway.
-}
-
-func (w *prefixSuffixSaver) Write(p []byte) (n int, err error) {
-	lenp := len(p)
-	p = w.fill(&w.prefix, p)
-
-	// Only keep the last w.N bytes of suffix data.
-	if overage := len(p) - w.N; overage > 0 {
-		p = p[overage:]
-		w.skipped += int64(overage)
-	}
-	p = w.fill(&w.suffix, p)
-
-	// w.suffix is full now if p is non-empty. Overwrite it in a circle.
-	for len(p) > 0 { // 0, 1, or 2 iterations.
-		n := copy(w.suffix[w.suffixOff:], p)
-		p = p[n:]
-		w.skipped += int64(n)
-		w.suffixOff += n
-		if w.suffixOff == w.N {
-			w.suffixOff = 0
-		}
-	}
-	return lenp, nil
-}
-
-// fill appends up to len(p) bytes of p to *dst, such that *dst does not
-// grow larger than w.N. It returns the un-appended suffix of p.
-func (w *prefixSuffixSaver) fill(dst *[]byte, p []byte) (pRemain []byte) {
-	if remain := w.N - len(*dst); remain > 0 {
-		add := minInt(len(p), remain)
-		*dst = append(*dst, p[:add]...)
-		p = p[add:]
-	}
-	return p
-}
-
-func (w *prefixSuffixSaver) Bytes() []byte {
-	if w.suffix == nil {
-		return w.prefix
-	}
-	if w.skipped == 0 {
-		return append(w.prefix, w.suffix...)
-	}
-	var buf bytes.Buffer
-	buf.Grow(len(w.prefix) + len(w.suffix) + 50)
-	buf.Write(w.prefix)
-	buf.WriteString("\n... omitting ")
-	buf.WriteString(strconv.FormatInt(w.skipped, 10))
-	buf.WriteString(" bytes ...\n")
-	buf.Write(w.suffix[w.suffixOff:])
-	buf.Write(w.suffix[:w.suffixOff])
-	return buf.Bytes()
-}
-
-func minInt(a, b int) int {
-	if a < b {
-		return a
-	}
-	return b
-}
-
-// dedupEnv returns a copy of env with any duplicates removed, in favor of
-// later values.
-// Items not of the normal environment "key=value" form are preserved unchanged.
-func dedupEnv(env []string) []string {
-	return dedupEnvCase(runtime.GOOS == "windows", env)
-}
-
-// dedupEnvCase is dedupEnv with a case option for testing.
-// If caseInsensitive is true, the case of keys is ignored.
-func dedupEnvCase(caseInsensitive bool, env []string) []string {
-	out := make([]string, 0, len(env))
-	saw := make(map[string]int, len(env)) // key => index into out
-	for _, kv := range env {
-		eq := strings.Index(kv, "=")
-		if eq < 0 {
-			out = append(out, kv)
-			continue
-		}
-		k := kv[:eq]
-		if caseInsensitive {
-			k = strings.ToLower(k)
-		}
-		if dupIdx, isDup := saw[k]; isDup {
-			out[dupIdx] = kv
-			continue
-		}
-		saw[k] = len(out)
-		out = append(out, kv)
-	}
-	return out
-}
-
-// addCriticalEnv adds any critical environment variables that are required
-// (or at least almost always required) on the operating system.
-// Currently this is only used for Windows.
-func addCriticalEnv(env []string) []string {
-	if runtime.GOOS != "windows" {
-		return env
-	}
-	for _, kv := range env {
-		eq := strings.Index(kv, "=")
-		if eq < 0 {
-			continue
-		}
-		k := kv[:eq]
-		if strings.EqualFold(k, "SYSTEMROOT") {
-			// We already have it.
-			return env
-		}
-	}
-	return append(env, "SYSTEMROOT="+os.Getenv("SYSTEMROOT"))
-}

tempfork/osexec/exec_unix.go

@@ -1,24 +0,0 @@
-// Copyright 2015 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// +build !plan9,!windows
-
-package exec
-
-import (
-	"os"
-	"syscall"
-)
-
-func init() {
-	skipStdinCopyError = func(err error) bool {
-		// Ignore EPIPE errors copying to stdin if the program
-		// completed successfully otherwise.
-		// See Issue 9173.
-		pe, ok := err.(*os.PathError)
-		return ok &&
-			pe.Op == "write" && pe.Path == "|1" &&
-			pe.Err == syscall.EPIPE
-	}
-}

tempfork/osexec/exec_windows.go

@@ -1,23 +0,0 @@
-// Copyright 2017 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package exec
-
-import (
-	"os"
-	"syscall"
-)
-
-func init() {
-	skipStdinCopyError = func(err error) bool {
-		// Ignore ERROR_BROKEN_PIPE and ERROR_NO_DATA errors copying
-		// to stdin if the program completed successfully otherwise.
-		// See Issue 20445.
-		const _ERROR_NO_DATA = syscall.Errno(0xe8)
-		pe, ok := err.(*os.PathError)
-		return ok &&
-			pe.Op == "write" && pe.Path == "|1" &&
-			(pe.Err == syscall.ERROR_BROKEN_PIPE || pe.Err == _ERROR_NO_DATA)
-	}
-}

tempfork/osexec/internal_test.go

@@ -1,61 +0,0 @@
-// Copyright 2015 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package exec
-
-import (
-	"io"
-	"testing"
-)
-
-func TestPrefixSuffixSaver(t *testing.T) {
-	tests := []struct {
-		N      int
-		writes []string
-		want   string
-	}{
-		{
-			N:      2,
-			writes: nil,
-			want:   "",
-		},
-		{
-			N:      2,
-			writes: []string{"a"},
-			want:   "a",
-		},
-		{
-			N:      2,
-			writes: []string{"abc", "d"},
-			want:   "abcd",
-		},
-		{
-			N:      2,
-			writes: []string{"abc", "d", "e"},
-			want:   "ab\n... omitting 1 bytes ...\nde",
-		},
-		{
-			N:      2,
-			writes: []string{"ab______________________yz"},
-			want:   "ab\n... omitting 22 bytes ...\nyz",
-		},
-		{
-			N:      2,
-			writes: []string{"ab_______________________y", "z"},
-			want:   "ab\n... omitting 23 bytes ...\nyz",
-		},
-	}
-	for i, tt := range tests {
-		w := &prefixSuffixSaver{N: tt.N}
-		for _, s := range tt.writes {
-			n, err := io.WriteString(w, s)
-			if err != nil || n != len(s) {
-				t.Errorf("%d. WriteString(%q) = %v, %v; want %v, %v", i, s, n, err, len(s), nil)
-			}
-		}
-		if got := string(w.Bytes()); got != tt.want {
-			t.Errorf("%d. Bytes = %q; want %q", i, got, tt.want)
-		}
-	}
-}

tempfork/osexec/lp_js.go

@@ -1,23 +0,0 @@
-// Copyright 2018 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// +build js,wasm
-
-package exec
-
-import (
-	"errors"
-)
-
-// ErrNotFound is the error resulting if a path search failed to find an executable file.
-var ErrNotFound = errors.New("executable file not found in $PATH")
-
-// LookPath searches for an executable named file in the
-// directories named by the PATH environment variable.
-// If file contains a slash, it is tried directly and the PATH is not consulted.
-// The result may be an absolute path or a path relative to the current directory.
-func LookPath(file string) (string, error) {
-	// Wasm can not execute processes, so act as if there are no executables at all.
-	return "", &Error{file, ErrNotFound}
-}

tempfork/osexec/lp_plan9.go

@@ -1,55 +0,0 @@
-// Copyright 2011 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package exec
-
-import (
-	"errors"
-	"os"
-	"path/filepath"
-	"strings"
-)
-
-// ErrNotFound is the error resulting if a path search failed to find an executable file.
-var ErrNotFound = errors.New("executable file not found in $path")
-
-func findExecutable(file string) error {
-	d, err := os.Stat(file)
-	if err != nil {
-		return err
-	}
-	if m := d.Mode(); !m.IsDir() && m&0111 != 0 {
-		return nil
-	}
-	return os.ErrPermission
-}
-
-// LookPath searches for an executable named file in the
-// directories named by the path environment variable.
-// If file begins with "/", "#", "./", or "../", it is tried
-// directly and the path is not consulted.
-// The result may be an absolute path or a path relative to the current directory.
-func LookPath(file string) (string, error) {
-	// skip the path lookup for these prefixes
-	skip := []string{"/", "#", "./", "../"}
-
-	for _, p := range skip {
-		if strings.HasPrefix(file, p) {
-			err := findExecutable(file)
-			if err == nil {
-				return file, nil
-			}
-			return "", &Error{file, err}
-		}
-	}
-
-	path := os.Getenv("path")
-	for _, dir := range filepath.SplitList(path) {
-		path := filepath.Join(dir, file)
-		if err := findExecutable(path); err == nil {
-			return path, nil
-		}
-	}
-	return "", &Error{file, ErrNotFound}
-}

tempfork/osexec/lp_test.go

@@ -1,33 +0,0 @@
-// Copyright 2011 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package exec
-
-import (
-	"testing"
-)
-
-var nonExistentPaths = []string{
-	"some-non-existent-path",
-	"non-existent-path/slashed",
-}
-
-func TestLookPathNotFound(t *testing.T) {
-	for _, name := range nonExistentPaths {
-		path, err := LookPath(name)
-		if err == nil {
-			t.Fatalf("LookPath found %q in $PATH", name)
-		}
-		if path != "" {
-			t.Fatalf("LookPath path == %q when err != nil", path)
-		}
-		perr, ok := err.(*Error)
-		if !ok {
-			t.Fatal("LookPath error is not an exec.Error")
-		}
-		if perr.Name != name {
-			t.Fatalf("want Error name %q, got %q", name, perr.Name)
-		}
-	}
-}

tempfork/osexec/lp_unix.go

@@ -1,58 +0,0 @@
-// Copyright 2010 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// +build aix darwin dragonfly freebsd linux nacl netbsd openbsd solaris
-
-package exec
-
-import (
-	"errors"
-	"os"
-	"path/filepath"
-	"strings"
-)
-
-// ErrNotFound is the error resulting if a path search failed to find an executable file.
-var ErrNotFound = errors.New("executable file not found in $PATH")
-
-func findExecutable(file string) error {
-	d, err := os.Stat(file)
-	if err != nil {
-		return err
-	}
-	if m := d.Mode(); !m.IsDir() && m&0111 != 0 {
-		return nil
-	}
-	return os.ErrPermission
-}
-
-// LookPath searches for an executable named file in the
-// directories named by the PATH environment variable.
-// If file contains a slash, it is tried directly and the PATH is not consulted.
-// The result may be an absolute path or a path relative to the current directory.
-func LookPath(file string) (string, error) {
-	// NOTE(rsc): I wish we could use the Plan 9 behavior here
-	// (only bypass the path if file begins with / or ./ or ../)
-	// but that would not match all the Unix shells.
-
-	if strings.Contains(file, "/") {
-		err := findExecutable(file)
-		if err == nil {
-			return file, nil
-		}
-		return "", &Error{file, err}
-	}
-	path := os.Getenv("PATH")
-	for _, dir := range filepath.SplitList(path) {
-		if dir == "" {
-			// Unix shell semantics: path element "" means "."
-			dir = "."
-		}
-		path := filepath.Join(dir, file)
-		if err := findExecutable(path); err == nil {
-			return path, nil
-		}
-	}
-	return "", &Error{file, ErrNotFound}
-}

tempfork/osexec/lp_unix_test.go

@@ -1,50 +0,0 @@
-// Copyright 2013 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// +build aix darwin dragonfly freebsd linux netbsd openbsd solaris
-
-package exec
-
-import (
-	"os"
-	"testing"
-)
-
-func TestLookPathUnixEmptyPath(t *testing.T) {
-	tmp := t.TempDir()
-	wd, err := os.Getwd()
-	if err != nil {
-		t.Fatal("Getwd failed: ", err)
-	}
-	err = os.Chdir(tmp)
-	if err != nil {
-		t.Fatal("Chdir failed: ", err)
-	}
-	defer os.Chdir(wd)
-
-	f, err := os.OpenFile("exec_me", os.O_CREATE|os.O_EXCL, 0700)
-	if err != nil {
-		t.Fatal("OpenFile failed: ", err)
-	}
-	err = f.Close()
-	if err != nil {
-		t.Fatal("Close failed: ", err)
-	}
-
-	pathenv := os.Getenv("PATH")
-	defer os.Setenv("PATH", pathenv)
-
-	err = os.Setenv("PATH", "")
-	if err != nil {
-		t.Fatal("Setenv failed: ", err)
-	}
-
-	path, err := LookPath("exec_me")
-	if err == nil {
-		t.Fatal("LookPath found exec_me in empty $PATH")
-	}
-	if path != "" {
-		t.Fatalf("LookPath path == %q when err != nil", path)
-	}
-}

tempfork/osexec/lp_windows.go

@@ -1,93 +0,0 @@
-// Copyright 2010 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package exec
-
-import (
-	"errors"
-	"os"
-	"path/filepath"
-	"strings"
-)
-
-// ErrNotFound is the error resulting if a path search failed to find an executable file.
-var ErrNotFound = errors.New("executable file not found in %PATH%")
-
-func chkStat(file string) error {
-	d, err := os.Stat(file)
-	if err != nil {
-		return err
-	}
-	if d.IsDir() {
-		return os.ErrPermission
-	}
-	return nil
-}
-
-func hasExt(file string) bool {
-	i := strings.LastIndex(file, ".")
-	if i < 0 {
-		return false
-	}
-	return strings.LastIndexAny(file, `:\/`) < i
-}
-
-func findExecutable(file string, exts []string) (string, error) {
-	if len(exts) == 0 {
-		return file, chkStat(file)
-	}
-	if hasExt(file) {
-		if chkStat(file) == nil {
-			return file, nil
-		}
-	}
-	for _, e := range exts {
-		if f := file + e; chkStat(f) == nil {
-			return f, nil
-		}
-	}
-	return "", os.ErrNotExist
-}
-
-// LookPath searches for an executable named file in the
-// directories named by the PATH environment variable.
-// If file contains a slash, it is tried directly and the PATH is not consulted.
-// LookPath also uses PATHEXT environment variable to match
-// a suitable candidate.
-// The result may be an absolute path or a path relative to the current directory.
-func LookPath(file string) (string, error) {
-	var exts []string
-	x := os.Getenv(`PATHEXT`)
-	if x != "" {
-		for _, e := range strings.Split(strings.ToLower(x), `;`) {
-			if e == "" {
-				continue
-			}
-			if e[0] != '.' {
-				e = "." + e
-			}
-			exts = append(exts, e)
-		}
-	} else {
-		exts = []string{".com", ".exe", ".bat", ".cmd"}
-	}
-
-	if strings.ContainsAny(file, `:\/`) {
-		if f, err := findExecutable(file, exts); err == nil {
-			return f, nil
-		} else {
-			return "", &Error{file, err}
-		}
-	}
-	if f, err := findExecutable(filepath.Join(".", file), exts); err == nil {
-		return f, nil
-	}
-	path := os.Getenv("path")
-	for _, dir := range filepath.SplitList(path) {
-		if f, err := findExecutable(filepath.Join(dir, file), exts); err == nil {
-			return f, nil
-		}
-	}
-	return "", &Error{file, ErrNotFound}
-}

tempfork/pprof/pprof.go

@@ -44,11 +44,12 @@ func AddHandlers(mux *http.ServeMux) {
 func Cmdline(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("X-Content-Type-Options", "nosniff")
 	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
-	fmt.Fprintf(w, strings.Join(os.Args, "\x00"))
+	fmt.Fprint(w, strings.Join(os.Args, "\x00"))
 }
 
 func sleep(w http.ResponseWriter, d time.Duration) {
 	var clientGone <-chan bool
+	//lint:ignore SA1019 CloseNotifier is deprecated but it functions and this is a temporary fork
 	if cn, ok := w.(http.CloseNotifier); ok {
 		clientGone = cn.CloseNotify()
 	}