VERSION.txt: this is v1.14.4

Signed-off-by: Denton Gentry <dgentry@tailscale.com>

Dockerfile

@@ -61,6 +61,6 @@ RUN go install -tags=xversion -ldflags="\
       -X tailscale.com/version.GitCommit=$VERSION_GIT_HASH" \
       -v ./cmd/...
 
-FROM alpine:3.11
+FROM alpine:3.14
 RUN apk add --no-cache ca-certificates iptables iproute2
 COPY --from=build-env /go/bin/* /usr/local/bin/

Makefile

@@ -18,7 +18,10 @@ buildwindows:
 build386:
 	GOOS=linux GOARCH=386 go install tailscale.com/cmd/tailscale tailscale.com/cmd/tailscaled
 
-check: staticcheck vet depaware buildwindows build386
+buildlinuxarm:
+	GOOS=linux GOARCH=arm go install tailscale.com/cmd/tailscale tailscale.com/cmd/tailscaled
+
+check: staticcheck vet depaware buildwindows build386 buildlinuxarm
 
 staticcheck:
 	go run honnef.co/go/tools/cmd/staticcheck -- $$(go list ./... | grep -v tempfork)

VERSION.txt

@@ -1 +1 @@
-1.13.0
+1.14.4

api.md

@@ -18,6 +18,7 @@ Currently based on {some authentication method}. Visit the [admin panel](https:/
     - [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
+	- [POST tailnet ACL validate](#tailnet-acl-validate-post): run validation tests against the tailnet's existing ACL
   - [Devices](#tailnet-devices)
     - [GET tailnet devices](#tailnet-devices-get)
   - [DNS](#tailnet-dns)
@@ -510,6 +511,50 @@ Response:
 {"matches":[{"users":["*"],"ports":["*:*"],"lineNumber":19}],"user":"user1@example.com"}
 ```
 
+<a name=tailnet-acl-validate-post></a>
+
+#### `POST /api/v2/tailnet/:tailnet/acl/validate` - run validation tests against the tailnet's active ACL
+
+Runs the provided ACL tests against the tailnet's existing ACL. This endpoint does not modify the ACL in any way.
+
+##### Parameters
+
+###### POST Body
+
+The POST body should be a JSON formatted array of ACL Tests.
+
+See https://tailscale.com/kb/1018/acls for more information on the format of ACL tests.
+
+##### Example
+```
+POST /api/v2/tailnet/example.com/acl/validate
+curl 'https://api.tailscale.com/api/v2/tailnet/example.com/acl/validate' \
+  -u "tskey-yourapikey123:" \
+  --data-binary '
+{
+  [
+    {"User": "user1@example.com", "Allow": ["example-host-1:22"], "Deny": ["example-host-2:100"]}
+  ]
+}'
+```
+
+Response:
+If all the tests pass, the response will be empty, with an http status code of 200.
+
+Failed test error response:
+A 400 http status code and the errors in the response body.  
+```
+{
+  "message":"test(s) failed",
+  "data":[
+           {
+             "user":"user1@example.com",
+             "errors":["address \"2.2.2.2:22\": want: Drop, got: Accept"]
+           }
+         ]
+}
+```
+
 <a name=tailnet-devices></a>
 
 ### Devices

client/tailscale/tailscale.go

@@ -8,6 +8,7 @@ package tailscale
 import (
 	"bytes"
 	"context"
+	"crypto/tls"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -16,15 +17,19 @@ import (
 	"net"
 	"net/http"
 	"net/url"
+	"os"
 	"strconv"
 	"strings"
+	"time"
 
+	"go4.org/mem"
 	"tailscale.com/client/tailscale/apitype"
 	"tailscale.com/ipn"
 	"tailscale.com/ipn/ipnstate"
 	"tailscale.com/paths"
 	"tailscale.com/safesocket"
 	"tailscale.com/tailcfg"
+	"tailscale.com/version"
 )
 
 // TailscaledSocket is the tailscaled Unix socket.
@@ -91,6 +96,9 @@ func send(ctx context.Context, method, path string, wantStatus int, body io.Read
 		return nil, err
 	}
 	defer res.Body.Close()
+	if server := res.Header.Get("Tailscale-Version"); server != version.Long {
+		fmt.Fprintf(os.Stderr, "Warning: client version %q != tailscaled server version %q\n", version.Long, server)
+	}
 	slurp, err := ioutil.ReadAll(res.Body)
 	if err != nil {
 		return nil, err
@@ -293,3 +301,69 @@ func CurrentDERPMap(ctx context.Context) (*tailcfg.DERPMap, error) {
 	}
 	return &derpMap, nil
 }
+
+// CertPair returns a cert and private key for the provided DNS domain.
+//
+// It returns a cached certificate from disk if it's still valid.
+func CertPair(ctx context.Context, domain string) (certPEM, keyPEM []byte, err error) {
+	res, err := send(ctx, "GET", "/localapi/v0/cert/"+domain+"?type=pair", 200, nil)
+	if err != nil {
+		return nil, nil, err
+	}
+	// with ?type=pair, the response PEM is first the one private
+	// key PEM block, then the cert PEM blocks.
+	i := mem.Index(mem.B(res), mem.S("--\n--"))
+	if i == -1 {
+		return nil, nil, fmt.Errorf("unexpected output: no delimiter")
+	}
+	i += len("--\n")
+	keyPEM, certPEM = res[:i], res[i:]
+	if mem.Contains(mem.B(certPEM), mem.S(" PRIVATE KEY-----")) {
+		return nil, nil, fmt.Errorf("unexpected output: key in cert")
+	}
+	return certPEM, keyPEM, nil
+}
+
+// GetCertificate fetches a TLS certificate for the TLS ClientHello in hi.
+//
+// It returns a cached certificate from disk if it's still valid.
+//
+// It's the right signature to use as the value of
+// tls.Config.GetCertificate.
+func GetCertificate(hi *tls.ClientHelloInfo) (*tls.Certificate, error) {
+	if hi == nil || hi.ServerName == "" {
+		return nil, errors.New("no SNI ServerName")
+	}
+	ctx, cancel := context.WithTimeout(context.Background(), time.Minute)
+	defer cancel()
+
+	name := hi.ServerName
+	if !strings.Contains(name, ".") {
+		if v, ok := ExpandSNIName(ctx, name); ok {
+			name = v
+		}
+	}
+	certPEM, keyPEM, err := CertPair(ctx, name)
+	if err != nil {
+		return nil, err
+	}
+	cert, err := tls.X509KeyPair(certPEM, keyPEM)
+	if err != nil {
+		return nil, err
+	}
+	return &cert, nil
+}
+
+// ExpandSNIName expands bare label name into the the most likely actual TLS cert name.
+func ExpandSNIName(ctx context.Context, name string) (fqdn string, ok bool) {
+	st, err := StatusWithoutPeers(ctx)
+	if err != nil {
+		return "", false
+	}
+	for _, d := range st.CertDomains {
+		if len(d) > len(name)+1 && strings.HasPrefix(d, name) && d[len(name)] == '.' {
+			return d, true
+		}
+	}
+	return "", false
+}

cmd/microproxy/microproxy.go

@@ -1,173 +0,0 @@
-// 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.
-
-// microproxy proxies incoming HTTPS connections to another
-// destination. Instead of managing its own TLS certificates, it
-// borrows issued certificates and keys from an autocert directory.
-package main
-
-import (
-	"crypto/tls"
-	"encoding/json"
-	"flag"
-	"fmt"
-	"io"
-	"io/ioutil"
-	"log"
-	"net/http"
-	"net/http/httputil"
-	"net/url"
-	"path/filepath"
-	"strings"
-	"sync"
-	"time"
-
-	"tailscale.com/logpolicy"
-	"tailscale.com/tsweb"
-)
-
-var (
-	addr          = flag.String("addr", ":4430", "server address")
-	certdir       = flag.String("certdir", "", "directory to borrow LetsEncrypt certificates from")
-	hostname      = flag.String("hostname", "", "hostname to serve")
-	logCollection = flag.String("logcollection", "", "If non-empty, logtail collection to log to")
-	nodeExporter  = flag.String("node-exporter", "http://localhost:9100", "URL of the local prometheus node exporter")
-	goVarsURL     = flag.String("go-vars-url", "http://localhost:8383/debug/vars", "URL of a local Go server's /debug/vars endpoint")
-	insecure      = flag.Bool("insecure", false, "serve over http, for development")
-)
-
-func main() {
-	flag.Parse()
-
-	if *logCollection != "" {
-		logpolicy.New(*logCollection)
-	}
-
-	ne, err := url.Parse(*nodeExporter)
-	if err != nil {
-		log.Fatalf("Couldn't parse URL %q: %v", *nodeExporter, err)
-	}
-	proxy := httputil.NewSingleHostReverseProxy(ne)
-	proxy.FlushInterval = time.Second
-
-	if _, err = url.Parse(*goVarsURL); err != nil {
-		log.Fatalf("Couldn't parse URL %q: %v", *goVarsURL, err)
-	}
-
-	mux := http.NewServeMux()
-	tsweb.Debugger(mux) // registers /debug/*
-	mux.Handle("/metrics", tsweb.Protected(proxy))
-	mux.Handle("/varz", tsweb.Protected(tsweb.StdHandler(&goVarsHandler{*goVarsURL}, tsweb.HandlerOptions{
-		Quiet200s: true,
-		Logf:      log.Printf,
-	})))
-
-	ch := &certHolder{
-		hostname: *hostname,
-		path:     filepath.Join(*certdir, *hostname),
-	}
-
-	httpsrv := &http.Server{
-		Addr:    *addr,
-		Handler: mux,
-	}
-
-	if !*insecure {
-		httpsrv.TLSConfig = &tls.Config{GetCertificate: ch.GetCertificate}
-		err = httpsrv.ListenAndServeTLS("", "")
-	} else {
-		err = httpsrv.ListenAndServe()
-	}
-	if err != nil && err != http.ErrServerClosed {
-		log.Fatal(err)
-	}
-}
-
-type goVarsHandler struct {
-	url string
-}
-
-func promPrint(w io.Writer, prefix string, obj map[string]interface{}) {
-	for k, i := range obj {
-		if prefix != "" {
-			k = prefix + "_" + k
-		}
-		switch v := i.(type) {
-		case map[string]interface{}:
-			promPrint(w, k, v)
-		case float64:
-			const saveConfigReject = "control_save_config_rejected_"
-			const saveConfig = "control_save_config_"
-			switch {
-			case strings.HasPrefix(k, saveConfigReject):
-				fmt.Fprintf(w, "control_save_config_rejected{reason=%q} %f\n", k[len(saveConfigReject):], v)
-			case strings.HasPrefix(k, saveConfig):
-				fmt.Fprintf(w, "control_save_config{reason=%q} %f\n", k[len(saveConfig):], v)
-			default:
-				fmt.Fprintf(w, "%s %f\n", k, v)
-			}
-		default:
-			fmt.Fprintf(w, "# Skipping key %q, unhandled type %T\n", k, v)
-		}
-	}
-}
-
-func (h *goVarsHandler) ServeHTTPReturn(w http.ResponseWriter, r *http.Request) error {
-	resp, err := http.Get(h.url)
-	if err != nil {
-		return tsweb.Error(http.StatusInternalServerError, "fetch failed", err)
-	}
-	defer resp.Body.Close()
-	var mon map[string]interface{}
-	if err := json.NewDecoder(resp.Body).Decode(&mon); err != nil {
-		return tsweb.Error(http.StatusInternalServerError, "fetch failed", err)
-	}
-
-	w.WriteHeader(http.StatusOK)
-	promPrint(w, "", mon)
-	return nil
-}
-
-// certHolder loads and caches a TLS certificate from disk, reloading
-// it every hour.
-type certHolder struct {
-	hostname string // only hostname allowed in SNI
-	path     string // path of certificate+key combined PEM file
-
-	mu     sync.Mutex
-	cert   *tls.Certificate // cached parsed cert+key
-	loaded time.Time
-}
-
-func (c *certHolder) GetCertificate(ch *tls.ClientHelloInfo) (*tls.Certificate, error) {
-	if ch.ServerName != c.hostname {
-		return nil, fmt.Errorf("wrong client SNI %q", ch.ServerName)
-	}
-	c.mu.Lock()
-	defer c.mu.Unlock()
-	if time.Since(c.loaded) > time.Hour {
-		if err := c.loadLocked(); err != nil {
-			log.Printf("Reloading cert %q: %v", c.path, err)
-			// continue anyway, we might be able to serve off the stale cert.
-		}
-	}
-	return c.cert, nil
-}
-
-// load reloads the TLS certificate and key from disk. Caller must
-// hold mu.
-func (c *certHolder) loadLocked() error {
-	bs, err := ioutil.ReadFile(c.path)
-	if err != nil {
-		return fmt.Errorf("reading %q: %v", c.path, err)
-	}
-	cert, err := tls.X509KeyPair(bs, bs)
-	if err != nil {
-		return fmt.Errorf("parsing %q: %v", c.path, err)
-	}
-
-	c.cert = &cert
-	c.loaded = time.Now()
-	return nil
-}

cmd/tailscale/cli/cert.go

@@ -0,0 +1,107 @@
+// 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 cli
+
+import (
+	"bytes"
+	"context"
+	"crypto/tls"
+	"flag"
+	"fmt"
+	"log"
+	"net/http"
+	"os"
+	"strings"
+
+	"github.com/peterbourgon/ff/v2/ffcli"
+	"tailscale.com/atomicfile"
+	"tailscale.com/client/tailscale"
+)
+
+var certCmd = &ffcli.Command{
+	Name:       "cert",
+	Exec:       runCert,
+	ShortHelp:  "get TLS certs",
+	ShortUsage: "cert [flags] <domain>",
+	FlagSet: (func() *flag.FlagSet {
+		fs := flag.NewFlagSet("cert", flag.ExitOnError)
+		fs.StringVar(&certArgs.certFile, "cert-file", "", "output cert file; defaults to DOMAIN.crt")
+		fs.StringVar(&certArgs.keyFile, "key-file", "", "output cert file; defaults to DOMAIN.key")
+		fs.BoolVar(&certArgs.serve, "serve-demo", false, "if true, serve on port :443 using the cert as a demo, instead of writing out the files to disk")
+		return fs
+	})(),
+}
+
+var certArgs struct {
+	certFile string
+	keyFile  string
+	serve    bool
+}
+
+func runCert(ctx context.Context, args []string) error {
+	if certArgs.serve {
+		s := &http.Server{
+			TLSConfig: &tls.Config{
+				GetCertificate: tailscale.GetCertificate,
+			},
+			Handler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				if r.TLS != nil && !strings.Contains(r.Host, ".") && r.Method == "GET" {
+					if v, ok := tailscale.ExpandSNIName(r.Context(), r.Host); ok {
+						http.Redirect(w, r, "https://"+v+r.URL.Path, http.StatusTemporaryRedirect)
+						return
+					}
+				}
+				fmt.Fprintf(w, "<h1>Hello from Tailscale</h1>It works.")
+			}),
+		}
+		log.Printf("running TLS server on :443 ...")
+		return s.ListenAndServeTLS("", "")
+	}
+
+	if len(args) != 1 {
+		return fmt.Errorf("Usage: tailscale cert [flags] <domain>")
+	}
+	domain := args[0]
+
+	if certArgs.certFile == "" {
+		certArgs.certFile = domain + ".crt"
+	}
+	if certArgs.keyFile == "" {
+		certArgs.keyFile = domain + ".key"
+	}
+	certPEM, keyPEM, err := tailscale.CertPair(ctx, domain)
+	if err != nil {
+		return err
+	}
+	certChanged, err := writeIfChanged(certArgs.certFile, certPEM, 0644)
+	if err != nil {
+		return err
+	}
+	if certChanged {
+		fmt.Printf("Wrote public cert to %v\n", certArgs.certFile)
+	} else {
+		fmt.Printf("Public cert unchanged at %v\n", certArgs.certFile)
+	}
+	keyChanged, err := writeIfChanged(certArgs.keyFile, keyPEM, 0600)
+	if err != nil {
+		return err
+	}
+	if keyChanged {
+		fmt.Printf("Wrote private key to %v\n", certArgs.keyFile)
+	} else {
+		fmt.Printf("Private key unchanged at %v\n", certArgs.keyFile)
+	}
+	return nil
+}
+
+func writeIfChanged(filename string, contents []byte, mode os.FileMode) (changed bool, err error) {
+	if old, err := os.ReadFile(filename); err == nil && bytes.Equal(contents, old) {
+		return false, nil
+	}
+	if err := atomicfile.WriteFile(filename, contents, mode); err != nil {
+		return false, err
+	}
+	return true, nil
+}

cmd/tailscale/cli/cli.go

@@ -107,6 +107,7 @@ change in the future.
 			webCmd,
 			fileCmd,
 			bugReportCmd,
+			certCmd,
 		},
 		FlagSet:   rootfs,
 		Exec:      func(context.Context, []string) error { return flag.ErrHelp },

cmd/tailscale/cli/up.go

@@ -478,6 +478,13 @@ func runUp(ctx context.Context, args []string) error {
 		}
 	}
 
+	// This whole 'up' mechanism is too complicated and results in
+	// hairy stuff like this select. We're ultimately waiting for
+	// 'startingOrRunning' to be done, but even in the case where
+	// it succeeds, other parts may shut down concurrently so we
+	// need to prioritize reads from 'startingOrRunning' if it's
+	// readable; its send does happen before the pump mechanism
+	// shuts down. (Issue 2333)
 	select {
 	case <-startingOrRunning:
 		return nil
@@ -489,6 +496,11 @@ func runUp(ctx context.Context, args []string) error {
 		}
 		return pumpCtx.Err()
 	case err := <-pumpErr:
+		select {
+		case <-startingOrRunning:
+			return nil
+		default:
+		}
 		return err
 	}
 }

cmd/tailscale/depaware.txt

@@ -4,7 +4,7 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
    W    github.com/alexbrainman/sspi/internal/common                 from github.com/alexbrainman/sspi/negotiate
    W 💣 github.com/alexbrainman/sspi/negotiate                       from tailscale.com/net/tshttpproxy
         github.com/kballard/go-shellquote                            from tailscale.com/cmd/tailscale/cli
-     💣 github.com/mitchellh/go-ps                                   from tailscale.com/cmd/tailscale/cli
+     💣 github.com/mitchellh/go-ps                                   from tailscale.com/cmd/tailscale/cli+
         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/goupnp                                  from github.com/tailscale/goupnp/dcps/internetgateway2+
@@ -20,8 +20,7 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         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
-        tailscale.com/atomicfile                                     from tailscale.com/ipn
+        tailscale.com/atomicfile                                     from tailscale.com/ipn+
         tailscale.com/client/tailscale                               from tailscale.com/cmd/tailscale/cli+
         tailscale.com/client/tailscale/apitype                       from tailscale.com/client/tailscale+
         tailscale.com/cmd/tailscale/cli                              from tailscale.com/cmd/tailscale
@@ -44,9 +43,9 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         tailscale.com/net/tlsdial                                    from tailscale.com/derp/derphttp
         tailscale.com/net/tsaddr                                     from tailscale.com/net/interfaces+
      💣 tailscale.com/net/tshttpproxy                                from tailscale.com/derp/derphttp+
-        tailscale.com/paths                                          from tailscale.com/cmd/tailscale/cli+
+     💣 tailscale.com/paths                                          from tailscale.com/cmd/tailscale/cli+
         tailscale.com/safesocket                                     from tailscale.com/cmd/tailscale/cli+
-        tailscale.com/syncs                                          from tailscale.com/net/interfaces+
+     💣 tailscale.com/syncs                                          from tailscale.com/net/interfaces+
         tailscale.com/tailcfg                                        from tailscale.com/cmd/tailscale/cli+
    W    tailscale.com/tsconst                                        from tailscale.com/net/interfaces
      💣 tailscale.com/tstime/mono                                    from tailscale.com/tstime/rate
@@ -101,9 +100,8 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         golang.org/x/time/rate                                       from tailscale.com/cmd/tailscale/cli+
         bufio                                                        from compress/flate+
         bytes                                                        from bufio+
-        compress/flate                                               from compress/gzip+
+        compress/flate                                               from compress/gzip
         compress/gzip                                                from net/http
-        compress/zlib                                                from debug/elf+
         container/list                                               from crypto/tls+
         context                                                      from crypto/tls+
         crypto                                                       from crypto/ecdsa+
@@ -126,10 +124,6 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         crypto/tls                                                   from github.com/tcnksm/go-httpstat+
         crypto/x509                                                  from crypto/tls+
         crypto/x509/pkix                                             from crypto/x509+
-        debug/dwarf                                                  from debug/elf+
-        debug/elf                                                    from rsc.io/goversion/version
-        debug/macho                                                  from rsc.io/goversion/version
-        debug/pe                                                     from rsc.io/goversion/version
         embed                                                        from tailscale.com/cmd/tailscale/cli
         encoding                                                     from encoding/json+
         encoding/asn1                                                from crypto/x509+
@@ -143,8 +137,7 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         expvar                                                       from tailscale.com/derp+
         flag                                                         from github.com/peterbourgon/ff/v2+
         fmt                                                          from compress/flate+
-        hash                                                         from compress/zlib+
-        hash/adler32                                                 from compress/zlib
+        hash                                                         from crypto+
         hash/crc32                                                   from compress/gzip+
         hash/maphash                                                 from go4.org/mem
         html                                                         from tailscale.com/ipn/ipnstate+
@@ -171,10 +164,10 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         os/exec                                                      from github.com/toqueteos/webbrowser+
         os/signal                                                    from tailscale.com/cmd/tailscale/cli
         os/user                                                      from tailscale.com/util/groupmember
-        path                                                         from debug/dwarf+
+        path                                                         from html/template+
         path/filepath                                                from crypto/x509+
         reflect                                                      from crypto/x509+
-        regexp                                                       from rsc.io/goversion/version+
+        regexp                                                       from github.com/tailscale/goupnp/httpu+
         regexp/syntax                                                from regexp
         runtime/debug                                                from golang.org/x/sync/singleflight
         sort                                                         from compress/flate+

cmd/tailscaled/depaware.txt

@@ -25,6 +25,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
    L 💣 github.com/mdlayher/netlink/nlenc                            from github.com/mdlayher/netlink+
    L    github.com/mdlayher/sdnotify                                 from tailscale.com/util/systemd
    L 💣 github.com/mdlayher/socket                                   from github.com/mdlayher/netlink
+     💣 github.com/mitchellh/go-ps                                   from tailscale.com/safesocket
    W    github.com/pkg/errors                                        from github.com/tailscale/certstore
    W 💣 github.com/tailscale/certstore                               from tailscale.com/control/controlclient
         github.com/tailscale/goupnp                                  from github.com/tailscale/goupnp/dcps/internetgateway2+
@@ -87,7 +88,6 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         inet.af/netstack/waiter                                      from inet.af/netstack/tcpip+
         inet.af/peercred                                             from tailscale.com/ipn/ipnserver
    W 💣 inet.af/wf                                                   from tailscale.com/wf
-        rsc.io/goversion/version                                     from tailscale.com/version
         tailscale.com/atomicfile                                     from tailscale.com/ipn+
         tailscale.com/client/tailscale                               from tailscale.com/derp
         tailscale.com/client/tailscale/apitype                       from tailscale.com/ipn/ipnlocal+
@@ -128,12 +128,12 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/net/tlsdial                                    from tailscale.com/control/controlclient+
         tailscale.com/net/tsaddr                                     from tailscale.com/ipn/ipnlocal+
      💣 tailscale.com/net/tshttpproxy                                from tailscale.com/control/controlclient+
-     💣 tailscale.com/net/tstun                                      from tailscale.com/cmd/tailscaled+
-        tailscale.com/paths                                          from tailscale.com/cmd/tailscaled+
+        tailscale.com/net/tstun                                      from tailscale.com/cmd/tailscaled+
+     💣 tailscale.com/paths                                          from tailscale.com/cmd/tailscaled+
         tailscale.com/portlist                                       from tailscale.com/ipn/ipnlocal
         tailscale.com/safesocket                                     from tailscale.com/ipn/ipnserver+
         tailscale.com/smallzstd                                      from tailscale.com/ipn/ipnserver+
-        tailscale.com/syncs                                          from tailscale.com/net/interfaces+
+     💣 tailscale.com/syncs                                          from tailscale.com/net/interfaces+
         tailscale.com/tailcfg                                        from tailscale.com/control/controlclient+
    W    tailscale.com/tsconst                                        from tailscale.com/net/interfaces
         tailscale.com/tstime                                         from tailscale.com/wgengine/magicsock
@@ -158,7 +158,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/util/dnsname                                   from tailscale.com/ipn/ipnstate+
   LW    tailscale.com/util/endian                                    from tailscale.com/net/netns+
         tailscale.com/util/groupmember                               from tailscale.com/ipn/ipnserver
-        tailscale.com/util/lineread                                  from tailscale.com/control/controlclient+
+        tailscale.com/util/lineread                                  from tailscale.com/hostinfo+
         tailscale.com/util/osshare                                   from tailscale.com/cmd/tailscaled+
         tailscale.com/util/pidowner                                  from tailscale.com/ipn/ipnserver
         tailscale.com/util/racebuild                                 from tailscale.com/logpolicy
@@ -166,7 +166,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/util/uniq                                      from tailscale.com/wgengine/magicsock
         tailscale.com/util/winutil                                   from tailscale.com/logpolicy+
         tailscale.com/version                                        from tailscale.com/cmd/tailscaled+
-        tailscale.com/version/distro                                 from tailscale.com/control/controlclient+
+        tailscale.com/version/distro                                 from tailscale.com/cmd/tailscaled+
    W    tailscale.com/wf                                             from tailscale.com/cmd/tailscaled
         tailscale.com/wgengine                                       from tailscale.com/cmd/tailscaled+
         tailscale.com/wgengine/filter                                from tailscale.com/control/controlclient+
@@ -178,6 +178,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/wgengine/wgcfg/nmcfg                           from tailscale.com/ipn/ipnlocal
         tailscale.com/wgengine/wglog                                 from tailscale.com/wgengine
    W 💣 tailscale.com/wgengine/winnet                                from tailscale.com/wgengine/router
+        golang.org/x/crypto/acme                                     from tailscale.com/ipn/localapi
         golang.org/x/crypto/blake2b                                  from golang.org/x/crypto/nacl/box
         golang.org/x/crypto/blake2s                                  from golang.zx2c4.com/wireguard/device+
         golang.org/x/crypto/chacha20                                 from golang.org/x/crypto/chacha20poly1305
@@ -216,9 +217,8 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         golang.org/x/time/rate                                       from inet.af/netstack/tcpip/stack+
         bufio                                                        from compress/flate+
         bytes                                                        from bufio+
-        compress/flate                                               from compress/gzip+
+        compress/flate                                               from compress/gzip
         compress/gzip                                                from internal/profile+
-        compress/zlib                                                from debug/elf+
         container/heap                                               from inet.af/netstack/tcpip/transport/tcp
         container/list                                               from crypto/tls+
         context                                                      from crypto/tls+
@@ -242,10 +242,6 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         crypto/tls                                                   from github.com/tcnksm/go-httpstat+
         crypto/x509                                                  from crypto/tls+
         crypto/x509/pkix                                             from crypto/x509+
-        debug/dwarf                                                  from debug/elf+
-        debug/elf                                                    from rsc.io/goversion/version
-        debug/macho                                                  from rsc.io/goversion/version
-        debug/pe                                                     from rsc.io/goversion/version
         embed                                                        from tailscale.com/net/dns+
         encoding                                                     from encoding/json+
         encoding/asn1                                                from crypto/x509+
@@ -259,8 +255,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         expvar                                                       from tailscale.com/derp+
         flag                                                         from tailscale.com/cmd/tailscaled+
         fmt                                                          from compress/flate+
-        hash                                                         from compress/zlib+
-        hash/adler32                                                 from compress/zlib
+        hash                                                         from crypto+
         hash/crc32                                                   from compress/gzip+
         hash/fnv                                                     from tailscale.com/wgengine/magicsock+
         hash/maphash                                                 from go4.org/mem
@@ -288,7 +283,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         os/exec                                                      from github.com/coreos/go-iptables/iptables+
         os/signal                                                    from tailscale.com/cmd/tailscaled+
         os/user                                                      from github.com/godbus/dbus/v5+
-        path                                                         from debug/dwarf+
+        path                                                         from github.com/godbus/dbus/v5+
         path/filepath                                                from crypto/x509+
         reflect                                                      from crypto/x509+
         regexp                                                       from github.com/coreos/go-iptables/iptables+

cmd/tailscaled/tailscaled.go

@@ -163,6 +163,34 @@ func main() {
 	}
 }
 
+func trySynologyMigration(p string) error {
+	if runtime.GOOS != "linux" || distro.Get() != distro.Synology {
+		return nil
+	}
+
+	fi, err := os.Stat(p)
+	if err == nil && fi.Size() > 0 || !os.IsNotExist(err) {
+		return err
+	}
+	// File is empty or doesn't exist, try reading from the old path.
+
+	const oldPath = "/var/packages/Tailscale/etc/tailscaled.state"
+	if _, err := os.Stat(oldPath); err != nil {
+		if os.IsNotExist(err) {
+			return nil
+		}
+		return err
+	}
+
+	if err := os.Chown(oldPath, os.Getuid(), os.Getgid()); err != nil {
+		return err
+	}
+	if err := os.Rename(oldPath, p); err != nil {
+		return err
+	}
+	return nil
+}
+
 func ipnServerOpts() (o ipnserver.Options) {
 	// Allow changing the OS-specific IPN behavior for tests
 	// so we can e.g. test Windows-specific behaviors on Linux.
@@ -225,6 +253,9 @@ func run() error {
 	if args.statepath == "" {
 		log.Fatalf("--state is required")
 	}
+	if err := trySynologyMigration(args.statepath); err != nil {
+		log.Printf("error in synology migration: %v", err)
+	}
 
 	var debugMux *http.ServeMux
 	if args.debug != "" {
@@ -335,9 +366,9 @@ func shouldWrapNetstack() bool {
 		return true
 	}
 	switch runtime.GOOS {
-	case "windows", "darwin":
+	case "windows", "darwin", "freebsd":
 		// Enable on Windows and tailscaled-on-macOS (this doesn't
-		// affect the GUI clients).
+		// affect the GUI clients), and on FreeBSD.
 		return true
 	}
 	return false

cmd/testcontrol/testcontrol.go

@@ -0,0 +1,98 @@
+// 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.
+
+// Program testcontrol runs a simple test control server.
+package main
+
+import (
+	"flag"
+	"log"
+	"net/http"
+	"testing"
+
+	"tailscale.com/tstest/integration"
+	"tailscale.com/tstest/integration/testcontrol"
+	"tailscale.com/types/logger"
+)
+
+var (
+	flagNFake = flag.Int("nfake", 0, "number of fake nodes to add to network")
+)
+
+func main() {
+	flag.Parse()
+
+	var t fakeTB
+	derpMap := integration.RunDERPAndSTUN(t, logger.Discard, "127.0.0.1")
+
+	control := &testcontrol.Server{
+		DERPMap:         derpMap,
+		ExplicitBaseURL: "http://127.0.0.1:9911",
+	}
+	for i := 0; i < *flagNFake; i++ {
+		control.AddFakeNode()
+	}
+	mux := http.NewServeMux()
+	mux.Handle("/", control)
+	addr := "127.0.0.1:9911"
+	log.Printf("listening on %s", addr)
+	err := http.ListenAndServe(addr, mux)
+	log.Fatal(err)
+}
+
+type fakeTB struct {
+	*testing.T
+}
+
+func (t fakeTB) Cleanup(_ func()) {}
+func (t fakeTB) Error(args ...interface{}) {
+	t.Fatal(args...)
+}
+func (t fakeTB) Errorf(format string, args ...interface{}) {
+	t.Fatalf(format, args...)
+}
+func (t fakeTB) Fail() {
+	t.Fatal("failed")
+}
+func (t fakeTB) FailNow() {
+	t.Fatal("failed")
+}
+func (t fakeTB) Failed() bool {
+	return false
+}
+func (t fakeTB) Fatal(args ...interface{}) {
+	log.Fatal(args...)
+}
+func (t fakeTB) Fatalf(format string, args ...interface{}) {
+	log.Fatalf(format, args...)
+}
+func (t fakeTB) Helper() {}
+func (t fakeTB) Log(args ...interface{}) {
+	log.Print(args...)
+}
+func (t fakeTB) Logf(format string, args ...interface{}) {
+	log.Printf(format, args...)
+}
+func (t fakeTB) Name() string {
+	return "faketest"
+}
+func (t fakeTB) Setenv(key string, value string) {
+	panic("not implemented")
+}
+func (t fakeTB) Skip(args ...interface{}) {
+	t.Fatal("skipped")
+}
+func (t fakeTB) SkipNow() {
+	t.Fatal("skipnow")
+}
+func (t fakeTB) Skipf(format string, args ...interface{}) {
+	t.Logf(format, args...)
+	t.Fatal("skipped")
+}
+func (t fakeTB) Skipped() bool {
+	return false
+}
+func (t fakeTB) TempDir() string {
+	panic("not implemented")
+}

control/controlclient/controlclient_test.go

@@ -75,10 +75,3 @@ func TestStatusEqual(t *testing.T) {
 		}
 	}
 }
-
-func TestOSVersion(t *testing.T) {
-	if osVersion == nil {
-		t.Skip("not available for OS")
-	}
-	t.Logf("Got: %#q", osVersion())
-}

control/controlclient/direct.go

@@ -20,7 +20,6 @@ import (
 	"net/url"
 	"os"
 	"os/exec"
-	"path/filepath"
 	"reflect"
 	"runtime"
 	"strconv"
@@ -33,6 +32,7 @@ import (
 	"inet.af/netaddr"
 	"tailscale.com/control/controlknobs"
 	"tailscale.com/health"
+	"tailscale.com/hostinfo"
 	"tailscale.com/ipn/ipnstate"
 	"tailscale.com/log/logheap"
 	"tailscale.com/net/dnscache"
@@ -47,9 +47,7 @@ import (
 	"tailscale.com/types/opt"
 	"tailscale.com/types/persist"
 	"tailscale.com/types/wgkey"
-	"tailscale.com/util/dnsname"
 	"tailscale.com/util/systemd"
-	"tailscale.com/version"
 	"tailscale.com/wgengine/monitor"
 )
 
@@ -184,53 +182,13 @@ func NewDirect(opts Options) (*Direct, error) {
 		pinger:                 opts.Pinger,
 	}
 	if opts.Hostinfo == nil {
-		c.SetHostinfo(NewHostinfo())
+		c.SetHostinfo(hostinfo.New())
 	} else {
 		c.SetHostinfo(opts.Hostinfo)
 	}
 	return c, nil
 }
 
-var osVersion func() string // non-nil on some platforms
-
-func NewHostinfo() *tailcfg.Hostinfo {
-	hostname, _ := os.Hostname()
-	hostname = dnsname.FirstLabel(hostname)
-	var osv string
-	if osVersion != nil {
-		osv = osVersion()
-	}
-	return &tailcfg.Hostinfo{
-		IPNVersion: version.Long,
-		Hostname:   hostname,
-		OS:         version.OS(),
-		OSVersion:  osv,
-		Package:    packageType(),
-		GoArch:     runtime.GOARCH,
-	}
-}
-
-func packageType() string {
-	switch runtime.GOOS {
-	case "windows":
-		if _, err := os.Stat(`C:\ProgramData\chocolatey\lib\tailscale`); err == nil {
-			return "choco"
-		}
-	case "darwin":
-		// Using tailscaled or IPNExtension?
-		exe, _ := os.Executable()
-		return filepath.Base(exe)
-	case "linux":
-		// Report whether this is in a snap.
-		// See https://snapcraft.io/docs/environment-variables
-		// We just look at two somewhat arbitrarily.
-		if os.Getenv("SNAP_NAME") != "" && os.Getenv("SNAP") != "" {
-			return "snap"
-		}
-	}
-	return ""
-}
-
 // SetHostinfo clones the provided Hostinfo and remembers it for the
 // next update. It reports whether the Hostinfo has changed.
 func (c *Direct) SetHostinfo(hi *tailcfg.Hostinfo) bool {
@@ -872,15 +830,14 @@ func (c *Direct) sendMapRequest(ctx context.Context, maxPolls int, cb func(*netm
 		nm.LocalPort = c.localPort
 		c.mu.Unlock()
 
-		// Printing the netmap can be extremely verbose, but is very
-		// handy for debugging. Let's limit how often we do it.
-		// Code elsewhere prints netmap diffs every time, so this
-		// occasional full dump, plus incremental diffs, should do
-		// the job.
+		// Occasionally print the netmap header.
+		// This is handy for debugging, and our logs processing
+		// pipeline depends on it. (TODO: Remove this dependency.)
+		// Code elsewhere prints netmap diffs every time they are received.
 		now := c.timeNow()
 		if now.Sub(c.lastPrintMap) >= 5*time.Minute {
 			c.lastPrintMap = now
-			c.logf("[v1] new network map[%d]:\n%s", i, nm.Concise())
+			c.logf("[v1] new network map[%d]:\n%s", i, nm.VeryConcise())
 		}
 
 		c.mu.Lock()
@@ -1303,3 +1260,59 @@ func (c *Direct) SetDNS(ctx context.Context, req *tailcfg.SetDNSRequest) error {
 
 	return nil
 }
+
+// tsmpPing sends a Ping to pr.IP, and sends an http request back to pr.URL
+// with ping response data.
+func tsmpPing(logf logger.Logf, c *http.Client, pr *tailcfg.PingRequest, pinger Pinger) error {
+	var err error
+	if pr.URL == "" {
+		return errors.New("invalid PingRequest with no URL")
+	}
+	if pr.IP.IsZero() {
+		return errors.New("PingRequest without IP")
+	}
+	if !strings.Contains(pr.Types, "TSMP") {
+		return fmt.Errorf("PingRequest with no TSMP in Types, got %q", pr.Types)
+	}
+
+	now := time.Now()
+	pinger.Ping(pr.IP, true, func(res *ipnstate.PingResult) {
+		// Currently does not check for error since we just return if it fails.
+		err = postPingResult(now, logf, c, pr, res)
+	})
+	return err
+}
+
+func postPingResult(now time.Time, logf logger.Logf, c *http.Client, pr *tailcfg.PingRequest, res *ipnstate.PingResult) error {
+	if res.Err != "" {
+		return errors.New(res.Err)
+	}
+	duration := time.Since(now)
+	if pr.Log {
+		logf("TSMP ping to %v completed in %v seconds. pinger.Ping took %v seconds", pr.IP, res.LatencySeconds, duration.Seconds())
+	}
+	ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
+	defer cancel()
+
+	jsonPingRes, err := json.Marshal(res)
+	if err != nil {
+		return err
+	}
+	// Send the results of the Ping, back to control URL.
+	req, err := http.NewRequestWithContext(ctx, "POST", pr.URL, bytes.NewBuffer(jsonPingRes))
+	if err != nil {
+		return fmt.Errorf("http.NewRequestWithContext(%q): %w", pr.URL, err)
+	}
+	if pr.Log {
+		logf("tsmpPing: sending ping results to %v ...", pr.URL)
+	}
+	t0 := time.Now()
+	_, err = c.Do(req)
+	d := time.Since(t0).Round(time.Millisecond)
+	if err != nil {
+		return fmt.Errorf("tsmpPing error: %w to %v (after %v)", err, pr.URL, d)
+	} else if pr.Log {
+		logf("tsmpPing complete to %v (after %v)", pr.URL, d)
+	}
+	return nil
+}

control/controlclient/direct_test.go

@@ -6,15 +6,20 @@ package controlclient
 
 import (
 	"encoding/json"
+	"net/http"
+	"net/http/httptest"
 	"testing"
+	"time"
 
 	"inet.af/netaddr"
+	"tailscale.com/hostinfo"
+	"tailscale.com/ipn/ipnstate"
 	"tailscale.com/tailcfg"
 	"tailscale.com/types/wgkey"
 )
 
 func TestNewDirect(t *testing.T) {
-	hi := NewHostinfo()
+	hi := hostinfo.New()
 	ni := tailcfg.NetInfo{LinkType: "wired"}
 	hi.NetInfo = &ni
 
@@ -56,7 +61,7 @@ func TestNewDirect(t *testing.T) {
 	if changed {
 		t.Errorf("c.SetHostinfo(hi) want false got %v", changed)
 	}
-	hi = NewHostinfo()
+	hi = hostinfo.New()
 	hi.Hostname = "different host name"
 	changed = c.SetHostinfo(hi)
 	if !changed {
@@ -92,14 +97,55 @@ func fakeEndpoints(ports ...uint16) (ret []tailcfg.Endpoint) {
 	return
 }
 
-func TestNewHostinfo(t *testing.T) {
-	hi := NewHostinfo()
-	if hi == nil {
-		t.Fatal("no Hostinfo")
+func TestTsmpPing(t *testing.T) {
+	hi := hostinfo.New()
+	ni := tailcfg.NetInfo{LinkType: "wired"}
+	hi.NetInfo = &ni
+
+	key, err := wgkey.NewPrivate()
+	if err != nil {
+		t.Error(err)
 	}
-	j, err := json.MarshalIndent(hi, "  ", "")
+	opts := Options{
+		ServerURL: "https://example.com",
+		Hostinfo:  hi,
+		GetMachinePrivateKey: func() (wgkey.Private, error) {
+			return key, nil
+		},
+	}
+
+	c, err := NewDirect(opts)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	pingRes := &ipnstate.PingResult{
+		IP:       "123.456.7890",
+		Err:      "",
+		NodeName: "testnode",
+	}
+
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		defer r.Body.Close()
+		body := new(ipnstate.PingResult)
+		if err := json.NewDecoder(r.Body).Decode(body); err != nil {
+			t.Fatal(err)
+		}
+		if pingRes.IP != body.IP {
+			t.Fatalf("PingResult did not have the correct IP : got %v, expected : %v", body.IP, pingRes.IP)
+		}
+		w.WriteHeader(200)
+	}))
+	defer ts.Close()
+
+	now := time.Now()
+
+	pr := &tailcfg.PingRequest{
+		URL: ts.URL,
+	}
+
+	err = postPingResult(now, t.Logf, c.httpc, pr, pingRes)
 	if err != nil {
 		t.Fatal(err)
 	}
-	t.Logf("Got: %s", j)
 }

derp/derp_server.go

@@ -1275,7 +1275,7 @@ func (s *Server) AddPacketForwarder(dst key.Public, fwd PacketForwarder) {
 			return
 		}
 		if m, ok := prev.(multiForwarder); ok {
-			if _, ok := m[fwd]; !ok {
+			if _, ok := m[fwd]; ok {
 				// Duplicate registration of same forwarder in set; ignore.
 				return
 			}

derp/derp_test.go

@@ -712,6 +712,7 @@ func TestForwarderRegistration(t *testing.T) {
 	// Adding a dup for a user.
 	wantCounter(&s.multiForwarderCreated, 0)
 	s.AddPacketForwarder(u1, testFwd(100))
+	s.AddPacketForwarder(u1, testFwd(100)) // dup to trigger dup path
 	want(map[key.Public]PacketForwarder{
 		u1: multiForwarder{
 			testFwd(1):   1,

go.mod

@@ -40,7 +40,7 @@ require (
 	golang.org/x/crypto v0.0.0-20210616213533-5ff15b29337e
 	golang.org/x/net v0.0.0-20210614182718-04defd469f4e
 	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c
-	golang.org/x/sys v0.0.0-20210616094352-59db8d763f22
+	golang.org/x/sys v0.0.0-20210817190340-bfb29a6856f2
 	golang.org/x/term v0.0.0-20210503060354-a79de5458b56
 	golang.org/x/time v0.0.0-20210611083556-38a9dc6acbc6
 	golang.org/x/tools v0.1.2
@@ -51,5 +51,4 @@ require (
 	inet.af/netstack v0.0.0-20210622165351-29b14ebc044e
 	inet.af/peercred v0.0.0-20210318190834-4259e17bb763
 	inet.af/wf v0.0.0-20210516214145-a5343001b756
-	rsc.io/goversion v1.2.0
 )

go.sum

@@ -810,8 +810,9 @@ golang.org/x/sys v0.0.0-20210423082822-04245dca01da/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20210510120138-977fb7262007/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20210525143221-35b2ab0089ea/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.0.0-20210616094352-59db8d763f22 h1:RqytpXGR1iVNX7psjB3ff8y7sNFinVFvkx1c8SjBkio=
 golang.org/x/sys v0.0.0-20210616094352-59db8d763f22/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20210817190340-bfb29a6856f2 h1:c8PlLMqBbOHoqtjteWm5/kbe6rNY2pbRfbIMVnepueo=
+golang.org/x/sys v0.0.0-20210817190340-bfb29a6856f2/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/term v0.0.0-20201117132131-f5c789dd3221/go.mod h1:Nr5EML6q2oocZ2LXRh80K7BxOlk5/8JxuGnuhpl+muw=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210503060354-a79de5458b56 h1:b8jxX3zqjpqb2LklXPzKSGJhzyxCOZSz8ncv8Nv+y7w=
@@ -987,5 +988,3 @@ mvdan.cc/lint v0.0.0-20170908181259-adc824a0674b/go.mod h1:2odslEg/xrtNQqCYg2/jC
 mvdan.cc/unparam v0.0.0-20200501210554-b37ab49443f7 h1:kAREL6MPwpsk1/PQPFD3Eg7WAQR5mPTWZJaBiG5LDbY=
 mvdan.cc/unparam v0.0.0-20200501210554-b37ab49443f7/go.mod h1:HGC5lll35J70Y5v7vCGb9oLhHoScFwkHDJm/05RdSTc=
 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=

hostinfo/hostinfo.go

@@ -4,20 +4,64 @@
 
 // Package hostinfo answers questions about the host environment that Tailscale is
 // running on.
-//
-// TODO(bradfitz): move more of control/controlclient/hostinfo_* into this package.
 package hostinfo
 
 import (
 	"io"
 	"os"
+	"path/filepath"
 	"runtime"
 	"sync/atomic"
 
 	"go4.org/mem"
+	"tailscale.com/tailcfg"
+	"tailscale.com/util/dnsname"
 	"tailscale.com/util/lineread"
+	"tailscale.com/version"
 )
 
+var osVersion func() string // non-nil on some platforms
+
+// New returns a partially populated Hostinfo for the current host.
+func New() *tailcfg.Hostinfo {
+	hostname, _ := os.Hostname()
+	hostname = dnsname.FirstLabel(hostname)
+	var osv string
+	if osVersion != nil {
+		osv = osVersion()
+	}
+	return &tailcfg.Hostinfo{
+		IPNVersion:  version.Long,
+		Hostname:    hostname,
+		OS:          version.OS(),
+		OSVersion:   osv,
+		Package:     packageType(),
+		GoArch:      runtime.GOARCH,
+		DeviceModel: deviceModel(),
+	}
+}
+
+func packageType() string {
+	switch runtime.GOOS {
+	case "windows":
+		if _, err := os.Stat(`C:\ProgramData\chocolatey\lib\tailscale`); err == nil {
+			return "choco"
+		}
+	case "darwin":
+		// Using tailscaled or IPNExtension?
+		exe, _ := os.Executable()
+		return filepath.Base(exe)
+	case "linux":
+		// Report whether this is in a snap.
+		// See https://snapcraft.io/docs/environment-variables
+		// We just look at two somewhat arbitrarily.
+		if os.Getenv("SNAP_NAME") != "" && os.Getenv("SNAP") != "" {
+			return "snap"
+		}
+	}
+	return ""
+}
+
 // EnvType represents a known environment type.
 // The empty string, the default, means unknown.
 type EnvType string
@@ -28,6 +72,7 @@ const (
 	Heroku          = EnvType("hr")
 	AzureAppService = EnvType("az")
 	AWSFargate      = EnvType("fg")
+	FlyDotIo        = EnvType("fly")
 )
 
 var envType atomic.Value // of EnvType
@@ -41,6 +86,16 @@ func GetEnvType() EnvType {
 	return e
 }
 
+var deviceModelAtomic atomic.Value // of string
+
+// SetDeviceModel sets the device model for use in Hostinfo updates.
+func SetDeviceModel(model string) { deviceModelAtomic.Store(model) }
+
+func deviceModel() string {
+	s, _ := deviceModelAtomic.Load().(string)
+	return s
+}
+
 func getEnvType() EnvType {
 	if inKnative() {
 		return KNative
@@ -57,11 +112,14 @@ func getEnvType() EnvType {
 	if inAWSFargate() {
 		return AWSFargate
 	}
+	if inFlyDotIo() {
+		return FlyDotIo
+	}
 	return ""
 }
 
-// InContainer reports whether we're running in a container.
-func InContainer() bool {
+// inContainer reports whether we're running in a container.
+func inContainer() bool {
 	if runtime.GOOS != "linux" {
 		return false
 	}
@@ -126,3 +184,10 @@ func inAWSFargate() bool {
 	}
 	return false
 }
+
+func inFlyDotIo() bool {
+	if os.Getenv("FLY_APP_NAME") != "" && os.Getenv("FLY_REGION") != "" {
+		return true
+	}
+	return false
+}

hostinfo/hostinfo_linux.go

@@ -5,22 +5,28 @@
 //go:build linux && !android
 // +build linux,!android
 
-package controlclient
+package hostinfo
 
 import (
 	"bytes"
 	"fmt"
 	"io/ioutil"
+	"os"
 	"strings"
 	"syscall"
 
-	"tailscale.com/hostinfo"
 	"tailscale.com/util/lineread"
 	"tailscale.com/version/distro"
 )
 
 func init() {
 	osVersion = osVersionLinux
+
+	if v, _ := os.ReadFile("/sys/firmware/devicetree/base/model"); len(v) > 0 {
+		// Look up "Raspberry Pi 4 Model B Rev 1.2",
+		// etc. Usually set on ARM SBCs.
+		SetDeviceModel(strings.Trim(string(v), "\x00\r\n\t "))
+	}
 }
 
 func osVersionLinux() string {
@@ -55,10 +61,10 @@ func osVersionLinux() string {
 		}
 		attrBuf.WriteByte(byte(b))
 	}
-	if hostinfo.InContainer() {
+	if inContainer() {
 		attrBuf.WriteString("; container")
 	}
-	if env := hostinfo.GetEnvType(); env != "" {
+	if env := GetEnvType(); env != "" {
 		fmt.Fprintf(&attrBuf, "; env=%s", env)
 	}
 	attr := attrBuf.String()

hostinfo/hostinfo_test.go

@@ -0,0 +1,29 @@
+// 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 hostinfo
+
+import (
+	"encoding/json"
+	"testing"
+)
+
+func TestNew(t *testing.T) {
+	hi := New()
+	if hi == nil {
+		t.Fatal("no Hostinfo")
+	}
+	j, err := json.MarshalIndent(hi, "  ", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Logf("Got: %s", j)
+}
+
+func TestOSVersion(t *testing.T) {
+	if osVersion == nil {
+		t.Skip("not available for OS")
+	}
+	t.Logf("Got: %#q", osVersion())
+}

hostinfo/hostinfo_windows.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package controlclient
+package hostinfo
 
 import (
 	"os/exec"

ipn/ipnlocal/local.go

@@ -29,6 +29,7 @@ import (
 	"tailscale.com/client/tailscale/apitype"
 	"tailscale.com/control/controlclient"
 	"tailscale.com/health"
+	"tailscale.com/hostinfo"
 	"tailscale.com/ipn"
 	"tailscale.com/ipn/ipnstate"
 	"tailscale.com/ipn/policy"
@@ -730,7 +731,7 @@ func (b *LocalBackend) Start(opts ipn.Options) error {
 		return nil
 	}
 
-	hostinfo := controlclient.NewHostinfo()
+	hostinfo := hostinfo.New()
 	hostinfo.BackendLogID = b.backendLogID
 	hostinfo.FrontendLogID = opts.FrontendLogID
 
@@ -783,8 +784,6 @@ func (b *LocalBackend) Start(opts ipn.Options) error {
 
 	b.inServerMode = b.prefs.ForceDaemon
 	b.serverURL = b.prefs.ControlURLOrDefault()
-	hostinfo.RoutableIPs = append(hostinfo.RoutableIPs, b.prefs.AdvertiseRoutes...)
-	hostinfo.RequestTags = append(hostinfo.RequestTags, b.prefs.AdvertiseTags...)
 	if b.inServerMode || runtime.GOOS == "windows" {
 		b.logf("Start: serverMode=%v", b.inServerMode)
 	}
@@ -851,6 +850,7 @@ func (b *LocalBackend) Start(opts ipn.Options) error {
 		DiscoPublicKey:       discoPublic,
 		DebugFlags:           debugFlags,
 		LinkMonitor:          b.e.GetLinkMonitor(),
+		Pinger:               b.e,
 
 		// Don't warn about broken Linux IP forwading when
 		// netstack is being used.
@@ -961,7 +961,7 @@ func (b *LocalBackend) updateFilter(netMap *netmap.NetworkMap, prefs *ipn.Prefs)
 		b.logf("netmap packet filter: (shields up)")
 		b.e.SetFilter(filter.NewShieldsUpFilter(localNets, logNets, oldFilter, b.logf))
 	} else {
-		b.logf("netmap packet filter: %v", packetFilter)
+		b.logf("netmap packet filter: %v filters", len(packetFilter))
 		b.e.SetFilter(filter.New(packetFilter, localNets, logNets, oldFilter, b.logf))
 	}
 }
@@ -1579,7 +1579,6 @@ func (b *LocalBackend) setPrefsLockedOnEntry(caller string, newp *ipn.Prefs) {
 
 	oldHi := b.hostinfo
 	newHi := oldHi.Clone()
-	newHi.RoutableIPs = append([]netaddr.IPPrefix(nil), b.prefs.AdvertiseRoutes...)
 	applyPrefsToHostinfo(newHi, newp)
 	b.hostinfo = newHi
 	hostInfoChanged := !oldHi.Equal(newHi)
@@ -1838,6 +1837,17 @@ func (b *LocalBackend) authReconfig() {
 			if err != nil {
 				b.logf("[unexpected] non-FQDN route suffix %q", suffix)
 			}
+
+			// Create map entry even if len(resolvers) == 0; Issue 2706.
+			// This lets the control plane send ExtraRecords for which we
+			// can authoritatively answer "name not exists" for when the
+			// control plane also sends this explicit but empty route
+			// making it as something we handle.
+			//
+			// While we're already populating it, might as well size the
+			// slice appropriately.
+			dcfg.Routes[fqdn] = make([]netaddr.IPPort, 0, len(resolvers))
+
 			for _, resolver := range resolvers {
 				res, err := parseResolver(resolver)
 				if err != nil {
@@ -2217,6 +2227,8 @@ func applyPrefsToHostinfo(hi *tailcfg.Hostinfo, prefs *ipn.Prefs) {
 	if m := prefs.DeviceModel; m != "" {
 		hi.DeviceModel = m
 	}
+	hi.RoutableIPs = append(prefs.AdvertiseRoutes[:0:0], prefs.AdvertiseRoutes...)
+	hi.RequestTags = append(prefs.AdvertiseTags[:0:0], prefs.AdvertiseTags...)
 	hi.ShieldsUp = prefs.ShieldsUp
 }
 

ipn/ipnlocal/peerapi_macios_ext.go

@@ -2,8 +2,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build (darwin && ts_macext) || (ios && ts_macext)
-// +build darwin,ts_macext ios,ts_macext
+//go:build ts_macext && (darwin || ios)
+// +build ts_macext
+// +build darwin ios
 
 package ipnlocal
 

ipn/ipnserver/server.go

@@ -20,6 +20,7 @@ import (
 	"os/exec"
 	"os/signal"
 	"os/user"
+	"path/filepath"
 	"runtime"
 	"strconv"
 	"strings"
@@ -37,6 +38,7 @@ import (
 	"tailscale.com/log/filelogger"
 	"tailscale.com/logtail/backoff"
 	"tailscale.com/net/netstat"
+	"tailscale.com/paths"
 	"tailscale.com/safesocket"
 	"tailscale.com/smallzstd"
 	"tailscale.com/types/logger"
@@ -581,6 +583,28 @@ func (s *server) writeToClients(n ipn.Notify) {
 	}
 }
 
+// tryWindowsAppDataMigration attempts to copy the Windows state file
+// from its old location to the new location. (Issue 2856)
+//
+// Tailscale 1.14 and before stored state under %LocalAppData%
+// (usually "C:\WINDOWS\system32\config\systemprofile\AppData\Local"
+// when tailscaled.exe is running as a non-user system service).
+// However it is frequently cleared for almost any reason: Windows
+// updates, System Restore, even various System Cleaner utilities.
+//
+// Returns a string of the path to use for the state file.
+// This will be a fallback %LocalAppData% path if migration fails,
+// a %ProgramData% path otherwise.
+func tryWindowsAppDataMigration(logf logger.Logf, path string) string {
+	if path != paths.DefaultTailscaledStateFile() {
+		// If they're specifying a non-default path, just trust that they know
+		// what they are doing.
+		return path
+	}
+	oldFile := filepath.Join(os.Getenv("LocalAppData"), "Tailscale", "server-state.conf")
+	return paths.TryConfigFileMigration(logf, oldFile, path)
+}
+
 // Run runs a Tailscale backend service.
 // The getEngine func is called repeatedly, once per connection, until it returns an engine successfully.
 func Run(ctx context.Context, logf logger.Logf, logid string, getEngine func() (wgengine.Engine, error), opts Options) error {
@@ -613,14 +637,18 @@ func Run(ctx context.Context, logf logger.Logf, logid string, getEngine func() (
 
 	var store ipn.StateStore
 	if opts.StatePath != "" {
-		store, err = ipn.NewFileStore(opts.StatePath)
+		path := opts.StatePath
+		if runtime.GOOS == "windows" {
+			path = tryWindowsAppDataMigration(logf, path)
+		}
+		store, err = ipn.NewFileStore(path)
 		if err != nil {
-			return fmt.Errorf("ipn.NewFileStore(%q): %v", opts.StatePath, err)
+			return fmt.Errorf("ipn.NewFileStore(%q): %v", path, err)
 		}
 		if opts.AutostartStateKey == "" {
 			autoStartKey, err := store.ReadState(ipn.ServerModeStartKey)
 			if err != nil && err != ipn.ErrStateNotExist {
-				return fmt.Errorf("calling ReadState on %s: %w", opts.StatePath, err)
+				return fmt.Errorf("calling ReadState on %s: %w", path, err)
 			}
 			key := string(autoStartKey)
 			if strings.HasPrefix(key, "user-") {

ipn/localapi/cert.go

@@ -0,0 +1,450 @@
+// 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.
+
+//go:build !ios && !android
+// +build !ios,!android
+
+package localapi
+
+import (
+	"bytes"
+	"context"
+	"crypto"
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/tls"
+	"crypto/x509"
+	"crypto/x509/pkix"
+	"encoding/json"
+	"encoding/pem"
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
+	"net"
+	"net/http"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	"golang.org/x/crypto/acme"
+	"tailscale.com/ipn/ipnstate"
+	"tailscale.com/paths"
+	"tailscale.com/types/logger"
+)
+
+// Process-wide cache. (A new *Handler is created per connection,
+// effectively per request)
+var (
+	// acmeMu guards all ACME operations, so concurrent requests
+	// for certs don't slam ACME. The first will go through and
+	// populate the on-disk cache and the rest should use that.
+	acmeMu sync.Mutex
+
+	renewMu        sync.Mutex // lock order: don't hold acmeMu and renewMu at the same time
+	lastRenewCheck = map[string]time.Time{}
+)
+
+func (h *Handler) certDir() (string, error) {
+	base := paths.DefaultTailscaledStateFile()
+	if base == "" {
+		return "", errors.New("no default DefaultTailscaledStateFile")
+	}
+	full := filepath.Join(filepath.Dir(base), "certs")
+	if err := os.MkdirAll(full, 0700); err != nil {
+		return "", err
+	}
+	return full, nil
+}
+
+var acmeDebug, _ = strconv.ParseBool(os.Getenv("TS_DEBUG_ACME"))
+
+func (h *Handler) serveCert(w http.ResponseWriter, r *http.Request) {
+	if !h.PermitWrite {
+		http.Error(w, "cert access denied", http.StatusForbidden)
+		return
+	}
+	dir, err := h.certDir()
+	if err != nil {
+		h.logf("certDir: %v", err)
+		http.Error(w, "failed to get cert dir", 500)
+		return
+	}
+
+	domain := strings.TrimPrefix(r.URL.Path, "/localapi/v0/cert/")
+	if domain == r.URL.Path {
+		http.Error(w, "internal handler config wired wrong", 500)
+		return
+	}
+
+	now := time.Now()
+	logf := logger.WithPrefix(h.logf, fmt.Sprintf("cert(%q): ", domain))
+	traceACME := func(v interface{}) {
+		if !acmeDebug {
+			return
+		}
+		j, _ := json.MarshalIndent(v, "", "\t")
+		log.Printf("acme %T: %s", v, j)
+	}
+
+	if pair, ok := h.getCertPEMCached(dir, domain, now); ok {
+		future := now.AddDate(0, 0, 14)
+		if h.shouldStartDomainRenewal(dir, domain, future) {
+			logf("starting async renewal")
+			// Start renewal in the background.
+			go h.getCertPEM(context.Background(), logf, traceACME, dir, domain, future)
+		}
+		serveKeyPair(w, r, pair)
+		return
+	}
+
+	pair, err := h.getCertPEM(r.Context(), logf, traceACME, dir, domain, now)
+	if err != nil {
+		logf("getCertPEM: %v", err)
+		http.Error(w, fmt.Sprint(err), 500)
+		return
+	}
+	serveKeyPair(w, r, pair)
+}
+
+func (h *Handler) shouldStartDomainRenewal(dir, domain string, future time.Time) bool {
+	renewMu.Lock()
+	defer renewMu.Unlock()
+	now := time.Now()
+	if last, ok := lastRenewCheck[domain]; ok && now.Sub(last) < time.Minute {
+		// We checked very recently. Don't bother reparsing &
+		// validating the x509 cert.
+		return false
+	}
+	lastRenewCheck[domain] = now
+	_, ok := h.getCertPEMCached(dir, domain, future)
+	return !ok
+}
+
+func serveKeyPair(w http.ResponseWriter, r *http.Request, p *keyPair) {
+	w.Header().Set("Content-Type", "text/plain")
+	switch r.URL.Query().Get("type") {
+	case "", "crt", "cert":
+		w.Write(p.certPEM)
+	case "key":
+		w.Write(p.keyPEM)
+	case "pair":
+		w.Write(p.keyPEM)
+		w.Write(p.certPEM)
+	default:
+		http.Error(w, `invalid type; want "cert" (default), "key", or "pair"`, 400)
+	}
+}
+
+type keyPair struct {
+	certPEM []byte
+	keyPEM  []byte
+	cached  bool
+}
+
+func keyFile(dir, domain string) string  { return filepath.Join(dir, domain+".key") }
+func certFile(dir, domain string) string { return filepath.Join(dir, domain+".crt") }
+
+// getCertPEMCached returns a non-nil keyPair and true if a cached
+// keypair for domain exists on disk in dir that is valid at the
+// provided now time.
+func (h *Handler) getCertPEMCached(dir, domain string, now time.Time) (p *keyPair, ok bool) {
+	if keyPEM, err := os.ReadFile(keyFile(dir, domain)); err == nil {
+		certPEM, _ := os.ReadFile(certFile(dir, domain))
+		if validCertPEM(domain, keyPEM, certPEM, now) {
+			return &keyPair{certPEM: certPEM, keyPEM: keyPEM, cached: true}, true
+		}
+	}
+	return nil, false
+}
+
+func (h *Handler) getCertPEM(ctx context.Context, logf logger.Logf, traceACME func(interface{}), dir, domain string, now time.Time) (*keyPair, error) {
+	acmeMu.Lock()
+	defer acmeMu.Unlock()
+
+	if p, ok := h.getCertPEMCached(dir, domain, now); ok {
+		return p, nil
+	}
+
+	key, err := acmeKey(dir)
+	if err != nil {
+		return nil, fmt.Errorf("acmeKey: %w", err)
+	}
+	ac := &acme.Client{Key: key}
+
+	a, err := ac.GetReg(ctx, "" /* pre-RFC param */)
+	switch {
+	case err == nil:
+		// Great, already registered.
+		logf("already had ACME account.")
+	case err == acme.ErrNoAccount:
+		a, err = ac.Register(ctx, new(acme.Account), acme.AcceptTOS)
+		if err == acme.ErrAccountAlreadyExists {
+			// Potential race. Double check.
+			a, err = ac.GetReg(ctx, "" /* pre-RFC param */)
+		}
+		if err != nil {
+			return nil, fmt.Errorf("acme.Register: %w", err)
+		}
+		logf("registered ACME account.")
+		traceACME(a)
+	default:
+		return nil, fmt.Errorf("acme.GetReg: %w", err)
+
+	}
+	if a.Status != acme.StatusValid {
+		return nil, fmt.Errorf("unexpected ACME account status %q", a.Status)
+	}
+
+	// Before hitting LetsEncrypt, see if this is a domain that Tailscale will do DNS challenges for.
+	st := h.b.StatusWithoutPeers()
+	if err := checkCertDomain(st, domain); err != nil {
+		return nil, err
+	}
+
+	order, err := ac.AuthorizeOrder(ctx, []acme.AuthzID{{Type: "dns", Value: domain}})
+	if err != nil {
+		return nil, err
+	}
+	traceACME(order)
+
+	for _, aurl := range order.AuthzURLs {
+		az, err := ac.GetAuthorization(ctx, aurl)
+		if err != nil {
+			return nil, err
+		}
+		traceACME(az)
+		for _, ch := range az.Challenges {
+			if ch.Type == "dns-01" {
+				rec, err := ac.DNS01ChallengeRecord(ch.Token)
+				if err != nil {
+					return nil, err
+				}
+				key := "_acme-challenge." + domain
+
+				var resolver net.Resolver
+				var ok bool
+				txts, _ := resolver.LookupTXT(ctx, key)
+				for _, txt := range txts {
+					if txt == rec {
+						ok = true
+						logf("TXT record already existed")
+						break
+					}
+				}
+				if !ok {
+					err = h.b.SetDNS(ctx, key, rec)
+					if err != nil {
+						return nil, fmt.Errorf("SetDNS %q => %q: %w", key, rec, err)
+					}
+					logf("did SetDNS")
+				}
+
+				chal, err := ac.Accept(ctx, ch)
+				if err != nil {
+					return nil, fmt.Errorf("Accept: %v", err)
+				}
+				traceACME(chal)
+				break
+			}
+		}
+	}
+
+	wait0 := time.Now()
+	orderURI := order.URI
+	for {
+		order, err = ac.WaitOrder(ctx, orderURI)
+		if err == nil {
+			break
+		}
+		if oe, ok := err.(*acme.OrderError); ok && oe.Status == acme.StatusInvalid {
+			if time.Since(wait0) > 2*time.Minute {
+				return nil, errors.New("timeout waiting for order to not be invalid")
+			}
+			log.Printf("order invalid; waiting...")
+			select {
+			case <-time.After(5 * time.Second):
+				continue
+			case <-ctx.Done():
+				return nil, ctx.Err()
+			}
+		}
+		return nil, fmt.Errorf("WaitOrder: %v", err)
+	}
+	traceACME(order)
+
+	certPrivKey, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	if err != nil {
+		return nil, err
+	}
+	var privPEM bytes.Buffer
+	if err := encodeECDSAKey(&privPEM, certPrivKey); err != nil {
+		return nil, err
+	}
+	if err := ioutil.WriteFile(keyFile(dir, domain), privPEM.Bytes(), 0600); err != nil {
+		return nil, err
+	}
+
+	csr, err := certRequest(certPrivKey, domain, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	der, _, err := ac.CreateOrderCert(ctx, order.FinalizeURL, csr, true)
+	if err != nil {
+		return nil, fmt.Errorf("CreateOrder: %v", err)
+	}
+
+	var certPEM bytes.Buffer
+	for _, b := range der {
+		pb := &pem.Block{Type: "CERTIFICATE", Bytes: b}
+		if err := pem.Encode(&certPEM, pb); err != nil {
+			return nil, err
+		}
+	}
+	if err := ioutil.WriteFile(certFile(dir, domain), certPEM.Bytes(), 0644); err != nil {
+		return nil, err
+	}
+
+	return &keyPair{certPEM: certPEM.Bytes(), keyPEM: privPEM.Bytes()}, nil
+}
+
+// certRequest generates a CSR for the given common name cn and optional SANs.
+func certRequest(key crypto.Signer, cn string, ext []pkix.Extension, san ...string) ([]byte, error) {
+	req := &x509.CertificateRequest{
+		Subject:         pkix.Name{CommonName: cn},
+		DNSNames:        san,
+		ExtraExtensions: ext,
+	}
+	return x509.CreateCertificateRequest(rand.Reader, req, key)
+}
+
+func encodeECDSAKey(w io.Writer, key *ecdsa.PrivateKey) error {
+	b, err := x509.MarshalECPrivateKey(key)
+	if err != nil {
+		return err
+	}
+	pb := &pem.Block{Type: "EC PRIVATE KEY", Bytes: b}
+	return pem.Encode(w, pb)
+}
+
+// parsePrivateKey is a copy of x/crypto/acme's parsePrivateKey.
+//
+// Attempt to parse the given private key DER block. OpenSSL 0.9.8 generates
+// PKCS#1 private keys by default, while OpenSSL 1.0.0 generates PKCS#8 keys.
+// OpenSSL ecparam generates SEC1 EC private keys for ECDSA. We try all three.
+//
+// Inspired by parsePrivateKey in crypto/tls/tls.go.
+func parsePrivateKey(der []byte) (crypto.Signer, error) {
+	if key, err := x509.ParsePKCS1PrivateKey(der); err == nil {
+		return key, nil
+	}
+	if key, err := x509.ParsePKCS8PrivateKey(der); err == nil {
+		switch key := key.(type) {
+		case *rsa.PrivateKey:
+			return key, nil
+		case *ecdsa.PrivateKey:
+			return key, nil
+		default:
+			return nil, errors.New("acme/autocert: unknown private key type in PKCS#8 wrapping")
+		}
+	}
+	if key, err := x509.ParseECPrivateKey(der); err == nil {
+		return key, nil
+	}
+
+	return nil, errors.New("acme/autocert: failed to parse private key")
+}
+
+func acmeKey(dir string) (crypto.Signer, error) {
+	pemName := filepath.Join(dir, "acme-account.key.pem")
+	if v, err := ioutil.ReadFile(pemName); err == nil {
+		priv, _ := pem.Decode(v)
+		if priv == nil || !strings.Contains(priv.Type, "PRIVATE") {
+			return nil, errors.New("acme/autocert: invalid account key found in cache")
+		}
+		return parsePrivateKey(priv.Bytes)
+	}
+
+	privKey, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	if err != nil {
+		return nil, err
+	}
+	var pemBuf bytes.Buffer
+	if err := encodeECDSAKey(&pemBuf, privKey); err != nil {
+		return nil, err
+	}
+	if err := ioutil.WriteFile(pemName, pemBuf.Bytes(), 0600); err != nil {
+		return nil, err
+	}
+	return privKey, nil
+}
+
+func validCertPEM(domain string, keyPEM, certPEM []byte, now time.Time) bool {
+	if len(keyPEM) == 0 || len(certPEM) == 0 {
+		return false
+	}
+	tlsCert, err := tls.X509KeyPair(certPEM, keyPEM)
+	if err != nil {
+		return false
+	}
+	var leaf *x509.Certificate
+	intermediates := x509.NewCertPool()
+	for i, certDER := range tlsCert.Certificate {
+		cert, err := x509.ParseCertificate(certDER)
+		if err != nil {
+			return false
+		}
+		if i == 0 {
+			leaf = cert
+		} else {
+			intermediates.AddCert(cert)
+		}
+	}
+	if leaf == nil {
+		return false
+	}
+	_, err = leaf.Verify(x509.VerifyOptions{
+		DNSName:       domain,
+		CurrentTime:   now,
+		Intermediates: intermediates,
+	})
+	return err == nil
+}
+
+func checkCertDomain(st *ipnstate.Status, domain string) error {
+	if domain == "" {
+		return errors.New("missing domain name")
+	}
+	for _, d := range st.CertDomains {
+		if d == domain {
+			return nil
+		}
+	}
+	// Transitional way while server doesn't yet populate CertDomains: also permit the client
+	// attempting Self.DNSName.
+	okay := st.CertDomains[:len(st.CertDomains):len(st.CertDomains)]
+	if st.Self != nil {
+		if v := strings.Trim(st.Self.DNSName, "."); v != "" {
+			if v == domain {
+				return nil
+			}
+			okay = append(okay, v)
+		}
+	}
+	switch len(okay) {
+	case 0:
+		return errors.New("your Tailscale account does not support getting TLS certs")
+	case 1:
+		return fmt.Errorf("invalid domain %q; only %q is permitted", domain, okay[0])
+	default:
+		return fmt.Errorf("invalid domain %q; must be one of %q", domain, okay)
+	}
+}

ipn/localapi/disabled_stubs.go

@@ -0,0 +1,17 @@
+// 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.
+
+//go:build ios || android
+// +build ios android
+
+package localapi
+
+import (
+	"net/http"
+	"runtime"
+)
+
+func (h *Handler) serveCert(w http.ResponseWriter, r *http.Request) {
+	http.Error(w, "disabled on "+runtime.GOOS, http.StatusNotFound)
+}

ipn/localapi/localapi.go

@@ -30,6 +30,7 @@ import (
 	"tailscale.com/ipn/ipnstate"
 	"tailscale.com/tailcfg"
 	"tailscale.com/types/logger"
+	"tailscale.com/version"
 )
 
 func randHex(n int) string {
@@ -64,6 +65,7 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "server has no local backend", http.StatusInternalServerError)
 		return
 	}
+	w.Header().Set("Tailscale-Version", version.Long)
 	if h.RequiredPassword != "" {
 		_, pass, ok := r.BasicAuth()
 		if !ok {
@@ -83,6 +85,10 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		h.serveFilePut(w, r)
 		return
 	}
+	if strings.HasPrefix(r.URL.Path, "/localapi/v0/cert/") {
+		h.serveCert(w, r)
+		return
+	}
 	switch r.URL.Path {
 	case "/localapi/v0/whois":
 		h.serveWhoIs(w, r)

ipn/store.go

@@ -16,6 +16,7 @@ import (
 	"sync"
 
 	"tailscale.com/atomicfile"
+	"tailscale.com/paths"
 )
 
 // ErrStateNotExist is returned by StateStore.ReadState when the
@@ -97,6 +98,11 @@ func (s *FileStore) String() string { return fmt.Sprintf("FileStore(%q)", s.path
 
 // NewFileStore returns a new file store that persists to path.
 func NewFileStore(path string) (*FileStore, error) {
+	// We unconditionally call this to ensure that our perms are correct
+	if err := paths.MkStateDir(filepath.Dir(path)); err != nil {
+		return nil, fmt.Errorf("creating state directory: %w", err)
+	}
+
 	bs, err := ioutil.ReadFile(path)
 
 	// Treat an empty file as a missing file.
@@ -110,7 +116,6 @@ func NewFileStore(path string) (*FileStore, error) {
 		if os.IsNotExist(err) {
 			// Write out an initial file, to verify that we can write
 			// to the path.
-			os.MkdirAll(filepath.Dir(path), 0755) // best effort
 			if err = atomicfile.WriteFile(path, []byte("{}"), 0600); err != nil {
 				return nil, err
 			}

log/filelogger/log.go

@@ -36,7 +36,7 @@ func New(fileBasePrefix, logID string, logf logger.Logf) logger.Logf {
 	if logf == nil {
 		panic("nil logf")
 	}
-	dir := filepath.Join(os.Getenv("LocalAppData"), "Tailscale", "Logs")
+	dir := filepath.Join(os.Getenv("ProgramData"), "Tailscale", "Logs")
 
 	if err := os.MkdirAll(dir, 0700); err != nil {
 		log.Printf("failed to create local log directory; not writing logs to disk: %v", err)

logpolicy/logpolicy.go

@@ -135,12 +135,33 @@ func logsDir(logf logger.Logf) string {
 		}
 	}
 
-	// STATE_DIRECTORY is set by systemd 240+ but we support older
-	// systems-d. For example, Ubuntu 18.04 (Bionic Beaver) is 237.
-	systemdStateDir := os.Getenv("STATE_DIRECTORY")
-	if systemdStateDir != "" {
-		logf("logpolicy: using $STATE_DIRECTORY, %q", systemdStateDir)
-		return systemdStateDir
+	switch runtime.GOOS {
+	case "windows":
+		if version.CmdName() == "tailscaled" {
+			// In the common case, when tailscaled is run as the Local System (as a service),
+			// we want to use %ProgramData% (C:\ProgramData\Tailscale), aside the
+			// system state config with the machine key, etc. But if that directory's
+			// not accessible, then it's probably because the user is running tailscaled
+			// as a regular user (perhaps in userspace-networking/SOCK5 mode) and we should
+			// just use the %LocalAppData% instead. In a user context, %LocalAppData% isn't
+			// subject to random deletions from Windows system updates.
+			dir := filepath.Join(os.Getenv("ProgramData"), "Tailscale")
+			if winProgramDataAccessible(dir) {
+				logf("logpolicy: using dir %v", dir)
+				return dir
+			}
+		}
+		dir := filepath.Join(os.Getenv("LocalAppData"), "Tailscale")
+		logf("logpolicy: using LocalAppData dir %v", dir)
+		return dir
+	case "linux":
+		// STATE_DIRECTORY is set by systemd 240+ but we support older
+		// systems-d. For example, Ubuntu 18.04 (Bionic Beaver) is 237.
+		systemdStateDir := os.Getenv("STATE_DIRECTORY")
+		if systemdStateDir != "" {
+			logf("logpolicy: using $STATE_DIRECTORY, %q", systemdStateDir)
+			return systemdStateDir
+		}
 	}
 
 	// Default to e.g. /var/lib/tailscale or /var/db/tailscale on Unix.
@@ -191,6 +212,23 @@ func redirectStderrToLogPanics() bool {
 	return runningUnderSystemd() || os.Getenv("TS_PLEASE_PANIC") != ""
 }
 
+// winProgramDataAccessible reports whether the directory (assumed to
+// be a Windows %ProgramData% directory) is accessible to the current
+// process. It's created if needed.
+func winProgramDataAccessible(dir string) bool {
+	if err := os.MkdirAll(dir, 0700); err != nil {
+		// TODO: windows ACLs
+		return false
+	}
+	// The C:\ProgramData\Tailscale directory should be locked down
+	// by with ACLs to only be readable by the local system so a
+	// regular user shouldn't be able to do this operation:
+	if _, err := os.ReadDir(dir); err != nil {
+		return false
+	}
+	return true
+}
+
 // tryFixLogStateLocation is a temporary fixup for
 // https://github.com/tailscale/tailscale/issues/247 . We accidentally
 // wrote logging state files to /, and then later to $CACHE_DIRECTORY
@@ -372,14 +410,44 @@ func New(collection string) *Policy {
 
 	cfgPath := filepath.Join(dir, fmt.Sprintf("%s.log.conf", cmdName))
 
-	// The Windows service previously ran as tailscale-ipn.exe, so
-	// let's keep using that log base name if it exists.
-	if runtime.GOOS == "windows" && cmdName == "tailscaled" {
-		const oldCmdName = "tailscale-ipn"
-		oldPath := filepath.Join(dir, oldCmdName+".log.conf")
-		if fi, err := os.Stat(oldPath); err == nil && fi.Mode().IsRegular() {
-			cfgPath = oldPath
-			cmdName = oldCmdName
+	if runtime.GOOS == "windows" {
+		switch cmdName {
+		case "tailscaled":
+			// Tailscale 1.14 and before stored state under %LocalAppData%
+			// (usually "C:\WINDOWS\system32\config\systemprofile\AppData\Local"
+			// when tailscaled.exe is running as a non-user system service).
+			// However it is frequently cleared for almost any reason: Windows
+			// updates, System Restore, even various System Cleaner utilities.
+			//
+			// The Windows service previously ran as tailscale-ipn.exe, so
+			// machines which ran very old versions might still have their
+			// log conf named %LocalAppData%\tailscale-ipn.log.conf
+			//
+			// Machines which started using Tailscale more recently will have
+			// %LocalAppData%\tailscaled.log.conf
+			//
+			// Attempt to migrate the log conf to C:\ProgramData\Tailscale
+			oldDir := filepath.Join(os.Getenv("LocalAppData"), "Tailscale")
+
+			oldPath := filepath.Join(oldDir, "tailscaled.log.conf")
+			if fi, err := os.Stat(oldPath); err != nil || !fi.Mode().IsRegular() {
+				// *Only* if tailscaled.log.conf does not exist,
+				// check for tailscale-ipn.log.conf
+				oldPathOldCmd := filepath.Join(oldDir, "tailscale-ipn.log.conf")
+				if fi, err := os.Stat(oldPathOldCmd); err == nil && fi.Mode().IsRegular() {
+					oldPath = oldPathOldCmd
+				}
+			}
+
+			cfgPath = paths.TryConfigFileMigration(earlyLogf, oldPath, cfgPath)
+		case "tailscale-ipn":
+			for _, oldBase := range []string{"wg64.log.conf", "wg32.log.conf"} {
+				oldConf := filepath.Join(dir, oldBase)
+				if fi, err := os.Stat(oldConf); err == nil && fi.Mode().IsRegular() {
+					cfgPath = paths.TryConfigFileMigration(earlyLogf, oldConf, cfgPath)
+					break
+				}
+			}
 		}
 	}
 

logtail/filch/filch.go

@@ -30,6 +30,15 @@ type Filch struct {
 	alt       *os.File
 	altscan   *bufio.Scanner
 	recovered int64
+	// buf is an initial buffer for altscan.
+	// As of August 2021, 99.96% of all log lines
+	// are below 4096 bytes in length.
+	// Since this cutoff is arbitrary, instead of using 4096,
+	// we subtract off the size of the rest of the struct
+	// so that the whole struct takes 4096 bytes
+	// (less on 32 bit platforms).
+	// This reduces allocation waste.
+	buf [4096 - 48]byte
 }
 
 // TryReadline implements the logtail.Buffer interface.
@@ -53,6 +62,7 @@ func (f *Filch) TryReadLine() ([]byte, error) {
 		return nil, err
 	}
 	f.altscan = bufio.NewScanner(f.alt)
+	f.altscan.Buffer(f.buf[:], bufio.MaxScanTokenSize)
 	f.altscan.Split(splitLines)
 	return f.scan()
 }
@@ -188,6 +198,7 @@ func New(filePrefix string, opts Options) (f *Filch, err error) {
 	}
 	if f.recovered > 0 {
 		f.altscan = bufio.NewScanner(f.alt)
+		f.altscan.Buffer(f.buf[:], bufio.MaxScanTokenSize)
 		f.altscan.Split(splitLines)
 	}
 

logtail/filch/filch_test.go

@@ -12,6 +12,7 @@ import (
 	"strings"
 	"testing"
 	"unicode"
+	"unsafe"
 )
 
 type filchTest struct {
@@ -169,3 +170,10 @@ func TestFilchStderr(t *testing.T) {
 		t.Errorf("unexpected write to fake stderr: %s", b)
 	}
 }
+
+func TestSizeOf(t *testing.T) {
+	s := unsafe.Sizeof(Filch{})
+	if s > 4096 {
+		t.Fatalf("Filch{} has size %d on %v, decrease size of buf field", s, runtime.GOARCH)
+	}
+}

logtail/logtail.go

@@ -200,9 +200,11 @@ func (l *Logger) drainBlock() (shuttingDown bool) {
 }
 
 // drainPending drains and encodes a batch of logs from the buffer for upload.
+// It uses scratch as its initial buffer.
 // If no logs are available, drainPending blocks until logs are available.
-func (l *Logger) drainPending() (res []byte) {
-	buf := new(bytes.Buffer)
+func (l *Logger) drainPending(scratch []byte) (res []byte) {
+	buf := bytes.NewBuffer(scratch[:0])
+	buf.WriteByte('[')
 	entries := 0
 
 	var batchDone bool
@@ -242,28 +244,15 @@ func (l *Logger) drainPending() (res []byte) {
 			b = l.encodeText(b, true)
 		}
 
-		switch {
-		case entries == 0:
-			buf.Write(b)
-		case entries == 1:
-			buf2 := new(bytes.Buffer)
-			buf2.WriteByte('[')
-			buf2.Write(buf.Bytes())
-			buf2.WriteByte(',')
-			buf2.Write(b)
-			buf.Reset()
-			buf.Write(buf2.Bytes())
-		default:
+		if entries > 0 {
 			buf.WriteByte(',')
-			buf.Write(b)
 		}
+		buf.Write(b)
 		entries++
 	}
 
-	if entries > 1 {
-		buf.WriteByte(']')
-	}
-	if buf.Len() == 0 {
+	buf.WriteByte(']')
+	if buf.Len() <= len("[]") {
 		return nil
 	}
 	return buf.Bytes()
@@ -273,8 +262,9 @@ func (l *Logger) drainPending() (res []byte) {
 func (l *Logger) uploading(ctx context.Context) {
 	defer close(l.shutdownDone)
 
+	scratch := make([]byte, 4096) // reusable buffer to write into
 	for {
-		body := l.drainPending()
+		body := l.drainPending(scratch)
 		origlen := -1 // sentinel value: uncompressed
 		// Don't attempt to compress tiny bodies; not worth the CPU cycles.
 		if l.zstdEncoder != nil && len(body) > 256 {

logtail/logtail_test.go

@@ -117,12 +117,7 @@ func TestEncodeAndUploadMessages(t *testing.T) {
 		io.WriteString(l, tt.log)
 		body := <-ts.uploaded
 
-		data := make(map[string]interface{})
-		err := json.Unmarshal(body, &data)
-		if err != nil {
-			t.Error(err)
-		}
-
+		data := unmarshalOne(t, body)
 		got := data["text"]
 		if got != tt.want {
 			t.Errorf("%s: got %q; want %q", tt.name, got.(string), tt.want)
@@ -154,11 +149,7 @@ func TestEncodeSpecialCases(t *testing.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)
-	}
+	data := unmarshalOne(t, body)
 	errorHasLogtail, ok := data["error_has_logtail"]
 	if ok {
 		if errorHasLogtail != "LOGTAIL" {
@@ -186,11 +177,7 @@ func TestEncodeSpecialCases(t *testing.T) {
 	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)
-	}
+	data = unmarshalOne(t, body)
 	_, ok = data["logtail"]
 	if ok {
 		t.Errorf("skipClientTime: unexpected logtail map present: %v", data)
@@ -204,11 +191,7 @@ func TestEncodeSpecialCases(t *testing.T) {
 	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)
-	}
+	data = unmarshalOne(t, body)
 	text, ok := data["text"]
 	if !ok {
 		t.Errorf("lowMem: no text %v", data)
@@ -219,7 +202,7 @@ func TestEncodeSpecialCases(t *testing.T) {
 
 	// -------------------------------------------------------------------------
 
-	err = l.Shutdown(context.Background())
+	err := l.Shutdown(context.Background())
 	if err != nil {
 		t.Error(err)
 	}
@@ -326,3 +309,16 @@ func TestPublicIDUnmarshalText(t *testing.T) {
 		t.Errorf("allocs = %v; want 0", n)
 	}
 }
+
+func unmarshalOne(t *testing.T, body []byte) map[string]interface{} {
+	t.Helper()
+	var entries []map[string]interface{}
+	err := json.Unmarshal(body, &entries)
+	if err != nil {
+		t.Error(err)
+	}
+	if len(entries) != 1 {
+		t.Fatalf("expected one entry, got %d", len(entries))
+	}
+	return entries[0]
+}

net/dns/direct.go

@@ -216,7 +216,8 @@ func (m directManager) restoreBackup() error {
 	if err != nil {
 		return err
 	}
-	if _, err := m.fs.Stat(resolvConf); err != nil && !os.IsNotExist(err) {
+	_, err = m.fs.Stat(resolvConf)
+	if err != nil && !os.IsNotExist(err) {
 		return err
 	}
 	resolvConfExists := !os.IsNotExist(err)
@@ -259,7 +260,7 @@ func (m directManager) SetDNS(config OSConfig) error {
 	// try to manage DNS through resolved when it's around, but as a
 	// best-effort fallback if we messed up the detection, try to
 	// restart resolved to make the system configuration consistent.
-	if isResolvedRunning() {
+	if isResolvedRunning() && !runningAsGUIDesktopUser() {
 		exec.Command("systemctl", "restart", "systemd-resolved.service").Run()
 	}
 
@@ -319,7 +320,7 @@ func (m directManager) Close() error {
 		return err
 	}
 
-	if isResolvedRunning() {
+	if isResolvedRunning() && !runningAsGUIDesktopUser() {
 		exec.Command("systemctl", "restart", "systemd-resolved.service").Run() // Best-effort.
 	}
 
@@ -385,3 +386,12 @@ func (fs directFS) ReadFile(name string) ([]byte, error) {
 func (fs directFS) WriteFile(name string, contents []byte, perm os.FileMode) error {
 	return ioutil.WriteFile(fs.path(name), contents, perm)
 }
+
+// runningAsGUIDesktopUser reports whether it seems that this code is
+// being run as a regular user on a Linux desktop. This is a quick
+// hack to fix Issue 2672 where PolicyKit pops up a GUI dialog asking
+// to proceed we do a best effort attempt to restart
+// systemd-resolved.service. There's surely a better way.
+func runningAsGUIDesktopUser() bool {
+	return os.Getuid() != 0 && os.Getenv("DISPLAY") != ""
+}

net/dns/resolver/forwarder.go

@@ -10,7 +10,6 @@ import (
 	"encoding/binary"
 	"errors"
 	"fmt"
-	"hash/crc32"
 	"io"
 	"io/ioutil"
 	"math/rand"
@@ -65,44 +64,13 @@ func getTxID(packet []byte) txid {
 	}
 
 	dnsid := binary.BigEndian.Uint16(packet[0:2])
-	qcount := binary.BigEndian.Uint16(packet[4:6])
-	if qcount == 0 {
-		return txid(dnsid)
-	}
-
-	offset := headerBytes
-	for i := uint16(0); i < qcount; i++ {
-		// Note: this relies on the fact that names are not compressed in questions,
-		// so they are guaranteed to end with a NUL byte.
-		//
-		// Justification:
-		// RFC 1035 doesn't seem to explicitly prohibit compressing names in questions,
-		// but this is exceedingly unlikely to be done in practice. A DNS request
-		// with multiple questions is ill-defined (which questions do the header flags apply to?)
-		// and a single question would have to contain a pointer to an *answer*,
-		// which would be excessively smart, pointless (an answer can just as well refer to the question)
-		// and perhaps even prohibited: a draft RFC (draft-ietf-dnsind-local-compression-05) states:
-		//
-		// > It is important that these pointers always point backwards.
-		//
-		// This is said in summarizing RFC 1035, although that phrase does not appear in the original RFC.
-		// Additionally, (https://cr.yp.to/djbdns/notes.html) states:
-		//
-		// > The precise rule is that a name can be compressed if it is a response owner name,
-		// > the name in NS data, the name in CNAME data, the name in PTR data, the name in MX data,
-		// > or one of the names in SOA data.
-		namebytes := bytes.IndexByte(packet[offset:], 0)
-		// ... | name | NUL | type | class
-		//        ??     1      2      2
-		offset = offset + namebytes + 5
-		if len(packet) < offset {
-			// Corrupt packet; don't crash.
-			return txid(dnsid)
-		}
-	}
-
-	hash := crc32.ChecksumIEEE(packet[headerBytes:offset])
-	return (txid(hash) << 32) | txid(dnsid)
+	// Previously, we hashed the question and combined it with the original txid
+	// which was useful when concurrent queries were multiplexed on a single
+	// local source port. We encountered some situations where the DNS server
+	// canonicalizes the question in the response (uppercase converted to
+	// lowercase in this case), which resulted in responses that we couldn't
+	// match to the original request due to hash mismatches.
+	return txid(dnsid)
 }
 
 // clampEDNSSize attempts to limit the maximum EDNS response size. This is not

net/dns/resolver/macios_ext.go

@@ -2,8 +2,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build (darwin && ts_macext) || (ios && ts_macext)
-// +build darwin,ts_macext ios,ts_macext
+//go:build ts_macext && (darwin || ios)
+// +build ts_macext
+// +build darwin ios
 
 package resolver
 

net/dns/resolver/tsdns_server_test.go

@@ -6,6 +6,7 @@ package resolver
 
 import (
 	"fmt"
+	"strings"
 	"testing"
 
 	"github.com/miekg/dns"
@@ -66,6 +67,58 @@ func resolveToIP(ipv4, ipv6 netaddr.IP, ns string) dns.HandlerFunc {
 	}
 }
 
+// resolveToIPLowercase returns a handler function which canonicalizes responses
+// by lowercasing the question and answer names, and responds
+// to queries of type A it receives with an A record containing ipv4,
+// to queries of type AAAA with an AAAA record containing ipv6,
+// to queries of type NS with an NS record containg name.
+func resolveToIPLowercase(ipv4, ipv6 netaddr.IP, ns string) dns.HandlerFunc {
+	return func(w dns.ResponseWriter, req *dns.Msg) {
+		m := new(dns.Msg)
+		m.SetReply(req)
+
+		if len(req.Question) != 1 {
+			panic("not a single-question request")
+		}
+		m.Question[0].Name = strings.ToLower(m.Question[0].Name)
+		question := req.Question[0]
+
+		var ans dns.RR
+		switch question.Qtype {
+		case dns.TypeA:
+			ans = &dns.A{
+				Hdr: dns.RR_Header{
+					Name:   question.Name,
+					Rrtype: dns.TypeA,
+					Class:  dns.ClassINET,
+				},
+				A: ipv4.IPAddr().IP,
+			}
+		case dns.TypeAAAA:
+			ans = &dns.AAAA{
+				Hdr: dns.RR_Header{
+					Name:   question.Name,
+					Rrtype: dns.TypeAAAA,
+					Class:  dns.ClassINET,
+				},
+				AAAA: ipv6.IPAddr().IP,
+			}
+		case dns.TypeNS:
+			ans = &dns.NS{
+				Hdr: dns.RR_Header{
+					Name:   question.Name,
+					Rrtype: dns.TypeNS,
+					Class:  dns.ClassINET,
+				},
+				Ns: ns,
+			}
+		}
+
+		m.Answer = append(m.Answer, ans)
+		w.WriteMsg(m)
+	}
+}
+
 // resolveToTXT returns a handler function which responds to queries of type TXT
 // it receives with the strings in txts.
 func resolveToTXT(txts []string, ednsMaxSize uint16) dns.HandlerFunc {

net/dns/resolver/tsdns_test.go

@@ -440,6 +440,8 @@ func TestDelegate(t *testing.T) {
 	records := []interface{}{
 		"test.site.",
 		resolveToIP(testipv4, testipv6, "dns.test.site."),
+		"LCtesT.SiTe.",
+		resolveToIPLowercase(testipv4, testipv6, "dns.test.site."),
 		"nxdomain.site.", resolveToNXDOMAIN,
 		"small.txt.", resolveToTXT(smallTXT, noEdns),
 		"smalledns.txt.", resolveToTXT(smallTXT, 512),
@@ -485,6 +487,21 @@ func TestDelegate(t *testing.T) {
 			dnspacket("test.site.", dns.TypeNS, noEdns),
 			dnsResponse{name: "dns.test.site.", rcode: dns.RCodeSuccess},
 		},
+		{
+			"ipv4",
+			dnspacket("LCtesT.SiTe.", dns.TypeA, noEdns),
+			dnsResponse{ip: testipv4, rcode: dns.RCodeSuccess},
+		},
+		{
+			"ipv6",
+			dnspacket("LCtesT.SiTe.", dns.TypeAAAA, noEdns),
+			dnsResponse{ip: testipv6, rcode: dns.RCodeSuccess},
+		},
+		{
+			"ns",
+			dnspacket("LCtesT.SiTe.", dns.TypeNS, noEdns),
+			dnsResponse{name: "dns.test.site.", rcode: dns.RCodeSuccess},
+		},
 		{
 			"nxdomain",
 			dnspacket("nxdomain.site.", dns.TypeA, noEdns),

net/dnsfallback/dns-fallback-servers.json

@@ -49,6 +49,34 @@
 				}
 			]
 		},
+		"12": {
+			"RegionID": 12,
+			"RegionCode": "r12",
+			"RegionName": "r12",
+			"Nodes": [
+				{
+					"Name": "12a",
+					"RegionID": 12,
+					"HostName": "derp12.tailscale.com",
+					"IPv4": "216.128.144.130",
+					"IPv6": "2001:19f0:5c01:289:5400:3ff:fe8d:cb5e"
+				},
+				{
+					"Name": "12b",
+					"RegionID": 12,
+					"HostName": "derp12b.tailscale.com",
+					"IPv4": "45.63.71.144",
+					"IPv6": "2001:19f0:5c01:48a:5400:3ff:fe8d:cb5f"
+				},
+				{
+					"Name": "12c",
+					"RegionID": 12,
+					"HostName": "derp12c.tailscale.com",
+					"IPv4": "149.28.119.105",
+					"IPv6": "2001:19f0:5c01:2cb:5400:3ff:fe8d:cb60"
+				}
+			]
+		},
 		"2": {
 			"RegionID": 2,
 			"RegionCode": "r2",
@@ -193,6 +221,20 @@
 					"HostName": "derp9.tailscale.com",
 					"IPv4": "207.148.3.137",
 					"IPv6": "2001:19f0:6401:1d9c:5400:2ff:feef:bb82"
+				},
+				{
+					"Name": "9b",
+					"RegionID": 9,
+					"HostName": "derp9b.tailscale.com",
+					"IPv4": "144.202.67.195",
+					"IPv6": "2001:19f0:6401:eb5:5400:3ff:fe8d:6d9b"
+				},
+				{
+					"Name": "9c",
+					"RegionID": 9,
+					"HostName": "derp9c.tailscale.com",
+					"IPv4": "155.138.243.219",
+					"IPv6": "2001:19f0:6401:fe7:5400:3ff:fe8d:6d9c"
 				}
 			]
 		}

net/interfaces/interfaces_windows.go

@@ -112,22 +112,36 @@ func NonTailscaleMTUs() (map[winipcfg.LUID]uint32, error) {
 	return mtus, err
 }
 
+func notTailscaleInterface(iface *winipcfg.IPAdapterAddresses) bool {
+	// TODO(bradfitz): do this without the Description method's
+	// utf16-to-string allocation. But at least we only do it for
+	// the virtual interfaces, for which there won't be many.
+	return !(iface.IfType == winipcfg.IfTypePropVirtual &&
+		iface.Description() == tsconst.WintunInterfaceDesc)
+}
+
 // NonTailscaleInterfaces returns a map of interface LUID to interface
 // for all interfaces except Tailscale tunnels.
 func NonTailscaleInterfaces() (map[winipcfg.LUID]*winipcfg.IPAdapterAddresses, error) {
-	ifs, err := winipcfg.GetAdaptersAddresses(windows.AF_UNSPEC, winipcfg.GAAFlagIncludeAllInterfaces)
+	return getInterfaces(windows.AF_UNSPEC, winipcfg.GAAFlagIncludeAllInterfaces, notTailscaleInterface)
+}
+
+// getInterfaces returns a map of interfaces keyed by their LUID for
+// all interfaces matching the provided match predicate.
+//
+// The family (AF_UNSPEC, AF_INET, or AF_INET6) and flags are passed
+// to winipcfg.GetAdaptersAddresses.
+func getInterfaces(family winipcfg.AddressFamily, flags winipcfg.GAAFlags, match func(*winipcfg.IPAdapterAddresses) bool) (map[winipcfg.LUID]*winipcfg.IPAdapterAddresses, error) {
+	ifs, err := winipcfg.GetAdaptersAddresses(family, flags)
 	if err != nil {
 		return nil, err
 	}
-
 	ret := map[winipcfg.LUID]*winipcfg.IPAdapterAddresses{}
 	for _, iface := range ifs {
-		if iface.Description() == tsconst.WintunInterfaceDesc {
-			continue
+		if match(iface) {
+			ret[iface.LUID] = iface
 		}
-		ret[iface.LUID] = iface
 	}
-
 	return ret, nil
 }
 
@@ -135,8 +149,26 @@ func NonTailscaleInterfaces() (map[winipcfg.LUID]*winipcfg.IPAdapterAddresses, e
 // default route for the given address family.
 //
 // It returns (nil, nil) if no interface is found.
+//
+// The family must be one of AF_INET or AF_INET6.
 func GetWindowsDefault(family winipcfg.AddressFamily) (*winipcfg.IPAdapterAddresses, error) {
-	ifs, err := NonTailscaleInterfaces()
+	ifs, err := getInterfaces(family, winipcfg.GAAFlagIncludeAllInterfaces, func(iface *winipcfg.IPAdapterAddresses) bool {
+		switch iface.IfType {
+		case winipcfg.IfTypeSoftwareLoopback:
+			return false
+		}
+		switch family {
+		case windows.AF_INET:
+			if iface.Flags&winipcfg.IPAAFlagIpv4Enabled == 0 {
+				return false
+			}
+		case windows.AF_INET6:
+			if iface.Flags&winipcfg.IPAAFlagIpv6Enabled == 0 {
+				return false
+			}
+		}
+		return iface.OperStatus == winipcfg.IfOperStatusUp && notTailscaleInterface(iface)
+	})
 	if err != nil {
 		return nil, err
 	}
@@ -149,12 +181,31 @@ func GetWindowsDefault(family winipcfg.AddressFamily) (*winipcfg.IPAdapterAddres
 	bestMetric := ^uint32(0)
 	var bestIface *winipcfg.IPAdapterAddresses
 	for _, route := range routes {
-		iface := ifs[route.InterfaceLUID]
-		if route.DestinationPrefix.PrefixLength != 0 || iface == nil {
+		if route.DestinationPrefix.PrefixLength != 0 {
+			// Not a default route.
 			continue
 		}
-		if iface.OperStatus == winipcfg.IfOperStatusUp && route.Metric < bestMetric {
-			bestMetric = route.Metric
+		iface := ifs[route.InterfaceLUID]
+		if iface == nil {
+			continue
+		}
+
+		// Microsoft docs say:
+		//
+		// "The actual route metric used to compute the route
+		// preferences for IPv4 is the summation of the route
+		// metric offset specified in the Metric member of the
+		// MIB_IPFORWARD_ROW2 structure and the interface
+		// metric specified in this member for IPv4"
+		metric := route.Metric
+		switch family {
+		case windows.AF_INET:
+			metric += iface.Ipv4Metric
+		case windows.AF_INET6:
+			metric += iface.Ipv6Metric
+		}
+		if metric < bestMetric {
+			bestMetric = metric
 			bestIface = iface
 		}
 	}
@@ -163,6 +214,9 @@ func GetWindowsDefault(family winipcfg.AddressFamily) (*winipcfg.IPAdapterAddres
 }
 
 func DefaultRouteInterface() (string, error) {
+	// We always return the IPv4 default route.
+	// TODO(bradfitz): adjust API if/when anything cares. They could in theory differ, though,
+	// in which case we might send traffic to the wrong interface.
 	iface, err := GetWindowsDefault(windows.AF_INET)
 	if err != nil {
 		return "", err

net/portmapper/igd_test.go

@@ -11,8 +11,11 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"sync"
+	"testing"
 
 	"inet.af/netaddr"
+	"tailscale.com/syncs"
+	"tailscale.com/types/logger"
 )
 
 // TestIGD is an IGD (Intenet Gateway Device) for testing. It supports fake
@@ -21,15 +24,26 @@ type TestIGD struct {
 	upnpConn net.PacketConn // for UPnP discovery
 	pxpConn  net.PacketConn // for NAT-PMP and/or PCP
 	ts       *httptest.Server
+	logf     logger.Logf
+	closed   syncs.AtomicBool
+
+	// do* will log which packets are sent, but will not reply to unexpected packets.
 
 	doPMP  bool
 	doPCP  bool
-	doUPnP bool // TODO: more options for 3 flavors of UPnP services
+	doUPnP bool
 
 	mu       sync.Mutex // guards below
 	counters igdCounters
 }
 
+// TestIGDOptions are options
+type TestIGDOptions struct {
+	PMP  bool
+	PCP  bool
+	UPnP bool // TODO: more options for 3 flavors of UPnP services
+}
+
 type igdCounters struct {
 	numUPnPDiscoRecv     int32
 	numUPnPOtherUDPRecv  int32
@@ -38,21 +52,28 @@ type igdCounters struct {
 	numPMPDiscoRecv      int32
 	numPCPRecv           int32
 	numPCPDiscoRecv      int32
+	numPCPMapRecv        int32
+	numPCPOtherRecv      int32
 	numPMPPublicAddrRecv int32
 	numPMPBogusRecv      int32
+
+	numFailedWrites  int32
+	invalidPCPMapPkt int32
 }
 
-func NewTestIGD() (*TestIGD, error) {
+func NewTestIGD(logf logger.Logf, t TestIGDOptions) (*TestIGD, error) {
 	d := &TestIGD{
-		doPMP:  true,
-		doPCP:  true,
-		doUPnP: true,
+		logf:   logf,
+		doPMP:  t.PMP,
+		doPCP:  t.PCP,
+		doUPnP: t.UPnP,
 	}
 	var err error
-	if d.upnpConn, err = net.ListenPacket("udp", "127.0.0.1:1900"); err != nil {
+	if d.upnpConn, err = testListenUDP(); err != nil {
 		return nil, err
 	}
-	if d.pxpConn, err = net.ListenPacket("udp", "127.0.0.1:5351"); err != nil {
+	if d.pxpConn, err = testListenUDP(); err != nil {
+		d.upnpConn.Close()
 		return nil, err
 	}
 	d.ts = httptest.NewServer(http.HandlerFunc(d.serveUPnPHTTP))
@@ -61,7 +82,24 @@ func NewTestIGD() (*TestIGD, error) {
 	return d, nil
 }
 
+func testListenUDP() (net.PacketConn, error) {
+	return net.ListenPacket("udp4", "127.0.0.1:0")
+}
+
+func (d *TestIGD) TestPxPPort() uint16 {
+	return uint16(d.pxpConn.LocalAddr().(*net.UDPAddr).Port)
+}
+
+func (d *TestIGD) TestUPnPPort() uint16 {
+	return uint16(d.upnpConn.LocalAddr().(*net.UDPAddr).Port)
+}
+
+func testIPAndGateway() (gw, ip netaddr.IP, ok bool) {
+	return netaddr.IPv4(127, 0, 0, 1), netaddr.IPv4(1, 2, 3, 4), true
+}
+
 func (d *TestIGD) Close() error {
+	d.closed.Set(true)
 	d.ts.Close()
 	d.upnpConn.Close()
 	d.pxpConn.Close()
@@ -89,13 +127,21 @@ func (d *TestIGD) serveUPnPDiscovery() {
 	for {
 		n, src, err := d.upnpConn.ReadFrom(buf)
 		if err != nil {
+			if !d.closed.Get() {
+				d.logf("serveUPnP failed: %v", err)
+			}
 			return
 		}
 		pkt := buf[:n]
 		if bytes.Equal(pkt, uPnPPacket) { // a super lazy "parse"
 			d.inc(&d.counters.numUPnPDiscoRecv)
 			resPkt := []byte(fmt.Sprintf("HTTP/1.1 200 OK\r\nCACHE-CONTROL: max-age=120\r\nST: urn:schemas-upnp-org:device:InternetGatewayDevice:1\r\nUSN: uuid:bee7052b-49e8-3597-b545-55a1e38ac11::urn:schemas-upnp-org:device:InternetGatewayDevice:1\r\nEXT:\r\nSERVER: Tailscale-Test/1.0 UPnP/1.1 MiniUPnPd/2.2.1\r\nLOCATION: %s\r\nOPT: \"http://schemas.upnp.org/upnp/1/0/\"; ns=01\r\n01-NLS: 1627958564\r\nBOOTID.UPNP.ORG: 1627958564\r\nCONFIGID.UPNP.ORG: 1337\r\n\r\n", d.ts.URL+"/rootDesc.xml"))
-			d.upnpConn.WriteTo(resPkt, src)
+			if d.doUPnP {
+				_, err = d.upnpConn.WriteTo(resPkt, src)
+				if err != nil {
+					d.inc(&d.counters.numFailedWrites)
+				}
+			}
 		} else {
 			d.inc(&d.counters.numUPnPOtherUDPRecv)
 		}
@@ -108,6 +154,9 @@ func (d *TestIGD) servePxP() {
 	for {
 		n, a, err := d.pxpConn.ReadFrom(buf)
 		if err != nil {
+			if !d.closed.Get() {
+				d.logf("servePxP failed: %v", err)
+			}
 			return
 		}
 		ua := a.(*net.UDPAddr)
@@ -151,5 +200,55 @@ func (d *TestIGD) handlePMPQuery(pkt []byte, src netaddr.IPPort) {
 
 func (d *TestIGD) handlePCPQuery(pkt []byte, src netaddr.IPPort) {
 	d.inc(&d.counters.numPCPRecv)
-	// TODO
+	if len(pkt) < 24 {
+		return
+	}
+	op := pkt[1]
+	pktSrcBytes := [16]byte{}
+	copy(pktSrcBytes[:], pkt[8:24])
+	pktSrc := netaddr.IPFrom16(pktSrcBytes)
+	if pktSrc != src.IP() {
+		// TODO this error isn't fatal but should be rejected by server.
+		// Since it's a test it's difficult to get them the same though.
+		d.logf("mismatch of packet source and source IP: got %v, expected %v", pktSrc, src.IP())
+	}
+	switch op {
+	case pcpOpAnnounce:
+		d.inc(&d.counters.numPCPDiscoRecv)
+		if !d.doPCP {
+			return
+		}
+		resp := buildPCPDiscoResponse(pkt)
+		if _, err := d.pxpConn.WriteTo(resp, src.UDPAddr()); err != nil {
+			d.inc(&d.counters.numFailedWrites)
+		}
+	case pcpOpMap:
+		if len(pkt) < 60 {
+			d.logf("got too short packet for pcp op map: %v", pkt)
+			d.inc(&d.counters.invalidPCPMapPkt)
+			return
+		}
+		d.inc(&d.counters.numPCPMapRecv)
+		if !d.doPCP {
+			return
+		}
+		resp := buildPCPMapResponse(pkt)
+		d.pxpConn.WriteTo(resp, src.UDPAddr())
+	default:
+		// unknown op code, ignore it for now.
+		d.inc(&d.counters.numPCPOtherRecv)
+		return
+	}
+}
+
+func newTestClient(t *testing.T, igd *TestIGD) *Client {
+	var c *Client
+	c = NewClient(t.Logf, func() {
+		t.Logf("port map changed")
+		t.Logf("have mapping: %v", c.HaveMapping())
+	})
+	c.testPxPPort = igd.TestPxPPort()
+	c.testUPnPPort = igd.TestUPnPPort()
+	c.SetGatewayLookupFunc(testIPAndGateway)
+	return c
 }

net/portmapper/pcp.go

@@ -12,7 +12,6 @@ import (
 	"time"
 
 	"inet.af/netaddr"
-	"tailscale.com/net/netns"
 )
 
 // References:
@@ -22,8 +21,8 @@ import (
 
 // PCP constants
 const (
-	pcpVersion = 2
-	pcpPort    = 5351
+	pcpVersion     = 2
+	pcpDefaultPort = 5351
 
 	pcpMapLifetimeSec = 7200 // TODO does the RFC recommend anything? This is taken from PMP.
 
@@ -39,7 +38,8 @@ const (
 )
 
 type pcpMapping struct {
-	gw       netaddr.IP
+	c        *Client
+	gw       netaddr.IPPort
 	internal netaddr.IPPort
 	external netaddr.IPPort
 
@@ -54,13 +54,13 @@ func (p *pcpMapping) GoodUntil() time.Time     { return p.goodUntil }
 func (p *pcpMapping) RenewAfter() time.Time    { return p.renewAfter }
 func (p *pcpMapping) External() netaddr.IPPort { return p.external }
 func (p *pcpMapping) Release(ctx context.Context) {
-	uc, err := netns.Listener().ListenPacket(ctx, "udp4", ":0")
+	uc, err := p.c.listenPacket(ctx, "udp4", ":0")
 	if err != nil {
 		return
 	}
 	defer uc.Close()
 	pkt := buildPCPRequestMappingPacket(p.internal.IP(), p.internal.Port(), p.external.Port(), 0, p.external.IP())
-	uc.WriteTo(pkt, netaddr.IPPortFrom(p.gw, pcpPort).UDPAddr())
+	uc.WriteTo(pkt, p.gw.UDPAddr())
 }
 
 // buildPCPRequestMappingPacket generates a PCP packet with a MAP opcode.
@@ -95,6 +95,8 @@ func buildPCPRequestMappingPacket(
 	return pkt
 }
 
+// parsePCPMapResponse parses resp into a partially populated pcpMapping.
+// In particular, its Client is not populated.
 func parsePCPMapResponse(resp []byte) (*pcpMapping, error) {
 	if len(resp) < 60 {
 		return nil, fmt.Errorf("Does not appear to be PCP MAP response")

net/portmapper/pcp_test.go

@@ -5,6 +5,7 @@
 package portmapper
 
 import (
+	"encoding/binary"
 	"testing"
 
 	"inet.af/netaddr"
@@ -25,3 +26,37 @@ func TestParsePCPMapResponse(t *testing.T) {
 		t.Errorf("mismatched external address, got: %v, want: %v", mapping.external, expectedAddr)
 	}
 }
+
+const (
+	serverResponseBit = 1 << 7
+	fakeLifetimeSec   = 1<<31 - 1
+)
+
+func buildPCPDiscoResponse(req []byte) []byte {
+	out := make([]byte, 24)
+	out[0] = pcpVersion
+	out[1] = req[1] | serverResponseBit
+	out[3] = 0
+	// Do not put an epoch time in 8:12, when we start using it, tests that use it should fail.
+	return out
+}
+
+func buildPCPMapResponse(req []byte) []byte {
+	out := make([]byte, 24+36)
+	out[0] = pcpVersion
+	out[1] = req[1] | serverResponseBit
+	out[3] = 0
+	binary.BigEndian.PutUint32(out[4:8], 1<<30)
+	// Do not put an epoch time in 8:12, when we start using it, tests that use it should fail.
+	mapResp := out[24:]
+	mapReq := req[24:]
+	// copy nonce, protocol and internal port
+	copy(mapResp[:13], mapReq[:13])
+	copy(mapResp[16:18], mapReq[16:18])
+	// assign external port
+	binary.BigEndian.PutUint16(mapResp[18:20], 4242)
+	assignedIP := netaddr.IPv4(127, 0, 0, 1)
+	assignedIP16 := assignedIP.As16()
+	copy(mapResp[20:36], assignedIP16[:])
+	return out
+}

net/portmapper/portmapper.go

@@ -14,6 +14,7 @@ import (
 	"io"
 	"net"
 	"net/http"
+	"os"
 	"sync"
 	"time"
 
@@ -55,6 +56,8 @@ type Client struct {
 	logf         logger.Logf
 	ipAndGateway func() (gw, ip netaddr.IP, ok bool)
 	onChange     func() // or nil
+	testPxPPort  uint16 // if non-zero, pxpPort to use for tests
+	testUPnPPort uint16 // if non-zero, uPnPPort to use for tests
 
 	mu sync.Mutex // guards following, and all fields thereof
 
@@ -113,7 +116,8 @@ func (c *Client) HaveMapping() bool {
 //
 // All fields are immutable once created.
 type pmpMapping struct {
-	gw         netaddr.IP
+	c          *Client
+	gw         netaddr.IPPort
 	external   netaddr.IPPort
 	internal   netaddr.IPPort
 	renewAfter time.Time // the time at which we want to renew the mapping
@@ -132,13 +136,13 @@ func (p *pmpMapping) External() netaddr.IPPort { return p.external }
 
 // Release does a best effort fire-and-forget release of the PMP mapping m.
 func (m *pmpMapping) Release(ctx context.Context) {
-	uc, err := netns.Listener().ListenPacket(ctx, "udp4", ":0")
+	uc, err := m.c.listenPacket(ctx, "udp4", ":0")
 	if err != nil {
 		return
 	}
 	defer uc.Close()
 	pkt := buildPMPRequestMappingPacket(m.internal.Port(), m.external.Port(), pmpMapLifetimeDelete)
-	uc.WriteTo(pkt, netaddr.IPPortFrom(m.gw, pmpPort).UDPAddr())
+	uc.WriteTo(pkt, m.gw.UDPAddr())
 }
 
 // NewClient returns a new portmapping client.
@@ -213,6 +217,44 @@ func (c *Client) gatewayAndSelfIP() (gw, myIP netaddr.IP, ok bool) {
 	return
 }
 
+// pxpPort returns the NAT-PMP and PCP port number.
+// It returns 5351, except for in tests where it varies by run.
+func (c *Client) pxpPort() uint16 {
+	if c.testPxPPort != 0 {
+		return c.testPxPPort
+	}
+	return pmpDefaultPort
+}
+
+// upnpPort returns the UPnP discovery port number.
+// It returns 1900, except for in tests where it varies by run.
+func (c *Client) upnpPort() uint16 {
+	if c.testUPnPPort != 0 {
+		return c.testUPnPPort
+	}
+	return upnpDefaultPort
+}
+
+func (c *Client) listenPacket(ctx context.Context, network, addr string) (net.PacketConn, error) {
+	// When running under testing conditions, we bind the IGD server
+	// to localhost, and may be running in an environment where our
+	// netns code would decide that binding the portmapper client
+	// socket to the default route interface is the correct way to
+	// ensure connectivity. This can result in us trying to send
+	// packets for 127.0.0.1 out the machine's LAN interface, which
+	// obviously gets dropped on the floor.
+	//
+	// So, under those testing conditions, do _not_ use netns to
+	// create listening sockets. Such sockets are vulnerable to
+	// routing loops, but it's tests that don't set up routing loops,
+	// so we don't care.
+	if c.testPxPPort != 0 || c.testUPnPPort != 0 || os.Getenv("GITHUB_ACTIONS") == "true" {
+		var lc net.ListenConfig
+		return lc.ListenPacket(ctx, network, addr)
+	}
+	return netns.Listener().ListenPacket(ctx, network, addr)
+}
+
 func (c *Client) invalidateMappingsLocked(releaseOld bool) {
 	if c.mapping != nil {
 		if releaseOld {
@@ -399,7 +441,8 @@ func (c *Client) createOrGetMapping(ctx context.Context) (external netaddr.IPPor
 	// PCP returns all the information necessary for a mapping in a single packet, so we can
 	// construct it upon receiving that packet.
 	m := &pmpMapping{
-		gw:       gw,
+		c:        c,
+		gw:       netaddr.IPPortFrom(gw, c.pxpPort()),
 		internal: internalAddr,
 	}
 	if haveRecentPMP {
@@ -415,7 +458,7 @@ func (c *Client) createOrGetMapping(ctx context.Context) (external netaddr.IPPor
 	}
 	c.mu.Unlock()
 
-	uc, err := netns.Listener().ListenPacket(ctx, "udp4", ":0")
+	uc, err := c.listenPacket(ctx, "udp4", ":0")
 	if err != nil {
 		return netaddr.IPPort{}, err
 	}
@@ -424,7 +467,7 @@ func (c *Client) createOrGetMapping(ctx context.Context) (external netaddr.IPPor
 	uc.SetReadDeadline(time.Now().Add(portMapServiceTimeout))
 	defer closeCloserOnContextDone(ctx, uc)()
 
-	pxpAddr := netaddr.IPPortFrom(gw, pmpPort)
+	pxpAddr := netaddr.IPPortFrom(gw, c.pxpPort())
 	pxpAddru := pxpAddr.UDPAddr()
 
 	preferPCP := !DisablePCP && (DisablePMP || (!haveRecentPMP && haveRecentPCP))
@@ -499,8 +542,9 @@ func (c *Client) createOrGetMapping(ctx context.Context) (external netaddr.IPPor
 					// PCP should only have a single packet response
 					return netaddr.IPPort{}, NoMappingError{ErrNoPortMappingServices}
 				}
+				pcpMapping.c = c
 				pcpMapping.internal = m.internal
-				pcpMapping.gw = gw
+				pcpMapping.gw = netaddr.IPPortFrom(gw, c.pxpPort())
 				c.mu.Lock()
 				defer c.mu.Unlock()
 				c.mapping = pcpMapping
@@ -524,7 +568,7 @@ type pmpResultCode uint16
 
 // NAT-PMP constants.
 const (
-	pmpPort              = 5351
+	pmpDefaultPort       = 5351
 	pmpMapLifetimeSec    = 7200 // RFC recommended 2 hour map duration
 	pmpMapLifetimeDelete = 0    // 0 second lifetime deletes
 
@@ -622,7 +666,7 @@ func (c *Client) Probe(ctx context.Context) (res ProbeResult, err error) {
 		}
 	}()
 
-	uc, err := netns.Listener().ListenPacket(context.Background(), "udp4", ":0")
+	uc, err := c.listenPacket(context.Background(), "udp4", ":0")
 	if err != nil {
 		c.logf("ProbePCP: %v", err)
 		return res, err
@@ -632,9 +676,8 @@ func (c *Client) Probe(ctx context.Context) (res ProbeResult, err error) {
 	defer cancel()
 	defer closeCloserOnContextDone(ctx, uc)()
 
-	pcpAddr := netaddr.IPPortFrom(gw, pcpPort).UDPAddr()
-	pmpAddr := netaddr.IPPortFrom(gw, pmpPort).UDPAddr()
-	upnpAddr := netaddr.IPPortFrom(gw, upnpPort).UDPAddr()
+	pxpAddr := netaddr.IPPortFrom(gw, c.pxpPort()).UDPAddr()
+	upnpAddr := netaddr.IPPortFrom(gw, c.upnpPort()).UDPAddr()
 
 	// Don't send probes to services that we recently learned (for
 	// the same gw/myIP) are available. See
@@ -642,12 +685,12 @@ func (c *Client) Probe(ctx context.Context) (res ProbeResult, err error) {
 	if c.sawPMPRecently() {
 		res.PMP = true
 	} else if !DisablePMP {
-		uc.WriteTo(pmpReqExternalAddrPacket, pmpAddr)
+		uc.WriteTo(pmpReqExternalAddrPacket, pxpAddr)
 	}
 	if c.sawPCPRecently() {
 		res.PCP = true
 	} else if !DisablePCP {
-		uc.WriteTo(pcpAnnounceRequest(myIP), pcpAddr)
+		uc.WriteTo(pcpAnnounceRequest(myIP), pxpAddr)
 	}
 	if c.sawUPnPRecently() {
 		res.UPnP = true
@@ -669,9 +712,9 @@ func (c *Client) Probe(ctx context.Context) (res ProbeResult, err error) {
 			}
 			return res, err
 		}
-		port := addr.(*net.UDPAddr).Port
+		port := uint16(addr.(*net.UDPAddr).Port)
 		switch port {
-		case upnpPort:
+		case c.upnpPort():
 			if mem.Contains(mem.B(buf[:n]), mem.S(":InternetGatewayDevice:")) {
 				meta, err := parseUPnPDiscoResponse(buf[:n])
 				if err != nil {
@@ -683,10 +726,13 @@ func (c *Client) Probe(ctx context.Context) (res ProbeResult, err error) {
 				res.UPnP = true
 				c.mu.Lock()
 				c.uPnPSawTime = time.Now()
-				c.uPnPMeta = meta
+				if c.uPnPMeta != meta {
+					c.logf("UPnP meta changed: %+v", meta)
+					c.uPnPMeta = meta
+				}
 				c.mu.Unlock()
 			}
-		case pcpPort: // same as pmpPort
+		case c.pxpPort(): // same value for PMP and PCP
 			if pres, ok := parsePCPResponse(buf[:n]); ok {
 				if pres.OpCode == pcpOpReply|pcpOpAnnounce {
 					pcpHeard = true
@@ -729,7 +775,7 @@ func (c *Client) Probe(ctx context.Context) (res ProbeResult, err error) {
 var pmpReqExternalAddrPacket = []byte{pmpVersion, pmpOpMapPublicAddr} // 0, 0
 
 const (
-	upnpPort = 1900 // for UDP discovery only; TCP port discovered later
+	upnpDefaultPort = 1900 // for UDP discovery only; TCP port discovered later
 )
 
 // uPnPPacket is the UPnP UDP discovery packet's request body.

net/portmapper/portmapper_test.go

@@ -7,12 +7,10 @@ package portmapper
 import (
 	"context"
 	"os"
+	"reflect"
 	"strconv"
 	"testing"
 	"time"
-
-	"inet.af/netaddr"
-	"tailscale.com/types/logger"
 )
 
 func TestCreateOrGetMapping(t *testing.T) {
@@ -60,28 +58,68 @@ func TestClientProbeThenMap(t *testing.T) {
 }
 
 func TestProbeIntegration(t *testing.T) {
-	igd, err := NewTestIGD()
+	igd, err := NewTestIGD(t.Logf, TestIGDOptions{PMP: true, PCP: true, UPnP: true})
 	if err != nil {
 		t.Fatal(err)
 	}
 	defer igd.Close()
 
-	logf := t.Logf
-	var c *Client
-	c = NewClient(logger.WithPrefix(logf, "portmapper: "), func() {
-		logf("portmapping changed.")
-		logf("have mapping: %v", c.HaveMapping())
-	})
-
-	c.SetGatewayLookupFunc(func() (gw, self netaddr.IP, ok bool) {
-		return netaddr.IPv4(127, 0, 0, 1), netaddr.IPv4(1, 2, 3, 4), true
-	})
+	c := newTestClient(t, igd)
+	t.Logf("Listening on pxp=%v, upnp=%v", c.testPxPPort, c.testUPnPPort)
+	defer c.Close()
 
 	res, err := c.Probe(context.Background())
 	if err != nil {
 		t.Fatalf("Probe: %v", err)
 	}
+	if !res.UPnP {
+		t.Errorf("didn't detect UPnP")
+	}
+	st := igd.stats()
+	want := igdCounters{
+		numUPnPDiscoRecv:     1,
+		numPMPRecv:           1,
+		numPCPRecv:           1,
+		numPCPDiscoRecv:      1,
+		numPMPPublicAddrRecv: 1,
+	}
+	if !reflect.DeepEqual(st, want) {
+		t.Errorf("unexpected stats:\n got: %+v\nwant: %+v", st, want)
+	}
+
 	t.Logf("Probe: %+v", res)
-	t.Logf("IGD stats: %+v", igd.stats())
+	t.Logf("IGD stats: %+v", st)
 	// TODO(bradfitz): finish
 }
+
+func TestPCPIntegration(t *testing.T) {
+	igd, err := NewTestIGD(t.Logf, TestIGDOptions{PMP: false, PCP: true, UPnP: false})
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer igd.Close()
+
+	c := newTestClient(t, igd)
+	defer c.Close()
+	res, err := c.Probe(context.Background())
+	if err != nil {
+		t.Fatalf("probe failed: %v", err)
+	}
+	if res.UPnP || res.PMP {
+		t.Errorf("probe unexpectedly saw upnp or pmp: %+v", res)
+	}
+	if !res.PCP {
+		t.Fatalf("probe did not see pcp: %+v", res)
+	}
+
+	external, err := c.createOrGetMapping(context.Background())
+	if err != nil {
+		t.Fatalf("failed to get mapping: %v", err)
+	}
+	if external.IsZero() {
+		t.Errorf("got zero IP, expected non-zero")
+	}
+	if c.mapping == nil {
+		t.Errorf("got nil mapping after successful createOrGetMapping")
+	}
+}

net/portmapper/upnp.go

@@ -311,6 +311,11 @@ func (c *Client) getUPnPPortMapping(
 
 type uPnPDiscoResponse struct {
 	Location string
+	// Server describes what version the UPnP is, such as MiniUPnPd/2.x.x
+	Server string
+	// USN is the serial number of the device, which also contains
+	// what kind of UPnP service is being offered, i.e. InternetGatewayDevice:2
+	USN string
 }
 
 // parseUPnPDiscoResponse parses a UPnP HTTP-over-UDP discovery response.
@@ -321,5 +326,7 @@ func parseUPnPDiscoResponse(body []byte) (uPnPDiscoResponse, error) {
 		return r, err
 	}
 	r.Location = res.Header.Get("Location")
+	r.Server = res.Header.Get("Server")
+	r.USN = res.Header.Get("Usn")
 	return r, nil
 }

net/portmapper/upnp_test.go

@@ -43,9 +43,13 @@ func TestParseUPnPDiscoResponse(t *testing.T) {
 	}{
 		{"google", googleWifiUPnPDisco, uPnPDiscoResponse{
 			Location: "http://192.168.86.1:5000/rootDesc.xml",
+			Server:   "Linux/5.4.0-1034-gcp UPnP/1.1 MiniUPnPd/1.9",
+			USN:      "uuid:a9708184-a6c0-413a-bbac-11bcf7e30ece::urn:schemas-upnp-org:device:InternetGatewayDevice:2",
 		}},
 		{"pfsense", pfSenseUPnPDisco, uPnPDiscoResponse{
 			Location: "http://192.168.1.1:2189/rootDesc.xml",
+			Server:   "FreeBSD/12.2-STABLE UPnP/1.1 MiniUPnPd/2.2.1",
+			USN:      "uuid:bee7052b-49e8-3597-b545-55a1e38ac11::urn:schemas-upnp-org:device:InternetGatewayDevice:1",
 		}},
 	}
 	for _, tt := range tests {

net/tstun/tap_linux.go

@@ -9,10 +9,9 @@ import (
 	"net"
 	"os"
 	"os/exec"
-	"syscall"
-	"unsafe"
 
 	"github.com/insomniacslk/dhcp/dhcpv4"
+	"golang.org/x/sys/unix"
 	"golang.zx2c4.com/wireguard/tun"
 	"inet.af/netaddr"
 	"inet.af/netstack/tcpip"
@@ -32,25 +31,30 @@ var ourMAC = net.HardwareAddr{0x30, 0x2D, 0x66, 0xEC, 0x7A, 0x93}
 
 func init() { createTAP = createTAPLinux }
 
-func createTAPLinux(tapName, bridgeName string) (dev tun.Device, err error) {
-	fd, err := syscall.Open("/dev/net/tun", syscall.O_RDWR, 0)
+func createTAPLinux(tapName, bridgeName string) (tun.Device, error) {
+	fd, err := unix.Open("/dev/net/tun", unix.O_RDWR, 0)
 	if err != nil {
 		return nil, err
 	}
-	var ifr struct {
-		name  [16]byte
-		flags uint16
-		_     [22]byte
+
+	dev, err := openDevice(fd, tapName, bridgeName)
+	if err != nil {
+		unix.Close(fd)
+		return nil, err
 	}
-	copy(ifr.name[:], tapName)
-	ifr.flags = syscall.IFF_TAP | syscall.IFF_NO_PI
-	_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, uintptr(fd), syscall.TUNSETIFF, uintptr(unsafe.Pointer(&ifr)))
-	if errno != 0 {
-		syscall.Close(fd)
-		return nil, errno
+
+	return dev, nil
+}
+
+func openDevice(fd int, tapName, bridgeName string) (tun.Device, error) {
+	ifr, err := unix.NewIfreq(tapName)
+	if err != nil {
+		return nil, err
 	}
-	if err = syscall.SetNonblock(fd, true); err != nil {
-		syscall.Close(fd)
+
+	// Flags are stored as a uint16 in the ifreq union.
+	ifr.SetUint16(unix.IFF_TAP | unix.IFF_NO_PI)
+	if err := unix.IoctlIfreq(fd, unix.TUNSETIFF, ifr); err != nil {
 		return nil, err
 	}
 
@@ -62,11 +66,13 @@ func createTAPLinux(tapName, bridgeName string) (dev tun.Device, err error) {
 			return nil, err
 		}
 	}
-	dev, _, err = tun.CreateUnmonitoredTUNFromFD(fd) // TODO: MTU
+
+	// Also sets non-blocking I/O on fd when creating tun.Device.
+	dev, _, err := tun.CreateUnmonitoredTUNFromFD(fd) // TODO: MTU
 	if err != nil {
-		syscall.Close(fd)
 		return nil, err
 	}
+
 	return dev, nil
 }
 

net/tstun/tun.go

@@ -7,10 +7,8 @@
 package tstun
 
 import (
-	"bytes"
 	"errors"
 	"os"
-	"os/exec"
 	"runtime"
 	"strconv"
 	"strings"
@@ -18,7 +16,6 @@ import (
 
 	"golang.zx2c4.com/wireguard/tun"
 	"tailscale.com/types/logger"
-	"tailscale.com/version/distro"
 )
 
 // tunMTU is the MTU we set on tailscale's TUN interface. wireguard-go
@@ -78,90 +75,18 @@ func New(logf logger.Logf, tunName string) (tun.Device, string, error) {
 	return dev, name, nil
 }
 
+// tunDiagnoseFailure, if non-nil, does OS-specific diagnostics of why
+// TUN failed to work.
+var tunDiagnoseFailure func(tunName string, logf logger.Logf)
+
 // Diagnose tries to explain a tuntap device creation failure.
 // It pokes around the system and logs some diagnostic info that might
 // help debug why tun creation failed. Because device creation has
 // already failed and the program's about to end, log a lot.
 func Diagnose(logf logger.Logf, tunName string) {
-	switch runtime.GOOS {
-	case "linux":
-		diagnoseLinuxTUNFailure(tunName, logf)
-	case "darwin":
-		diagnoseDarwinTUNFailure(tunName, logf)
-	default:
+	if tunDiagnoseFailure != nil {
+		tunDiagnoseFailure(tunName, logf)
+	} else {
 		logf("no TUN failure diagnostics for OS %q", runtime.GOOS)
 	}
 }
-
-func diagnoseDarwinTUNFailure(tunName string, logf logger.Logf) {
-	if os.Getuid() != 0 {
-		logf("failed to create TUN device as non-root user; use 'sudo tailscaled', or run under launchd with 'sudo tailscaled install-system-daemon'")
-	}
-	if tunName != "utun" {
-		logf("failed to create TUN device %q; try using tun device \"utun\" instead for automatic selection", tunName)
-	}
-}
-
-func diagnoseLinuxTUNFailure(tunName string, logf logger.Logf) {
-	kernel, err := exec.Command("uname", "-r").Output()
-	kernel = bytes.TrimSpace(kernel)
-	if err != nil {
-		logf("no TUN, and failed to look up kernel version: %v", err)
-		return
-	}
-	logf("Linux kernel version: %s", kernel)
-
-	modprobeOut, err := exec.Command("/sbin/modprobe", "tun").CombinedOutput()
-	if err == nil {
-		logf("'modprobe tun' successful")
-		// Either tun is currently loaded, or it's statically
-		// compiled into the kernel (which modprobe checks
-		// with /lib/modules/$(uname -r)/modules.builtin)
-		//
-		// So if there's a problem at this point, it's
-		// probably because /dev/net/tun doesn't exist.
-		const dev = "/dev/net/tun"
-		if fi, err := os.Stat(dev); err != nil {
-			logf("tun module loaded in kernel, but %s does not exist", dev)
-		} else {
-			logf("%s: %v", dev, fi.Mode())
-		}
-
-		// We failed to find why it failed. Just let our
-		// caller report the error it got from wireguard-go.
-		return
-	}
-	logf("is CONFIG_TUN enabled in your kernel? `modprobe tun` failed with: %s", modprobeOut)
-
-	switch distro.Get() {
-	case distro.Debian:
-		dpkgOut, err := exec.Command("dpkg", "-S", "kernel/drivers/net/tun.ko").CombinedOutput()
-		if len(bytes.TrimSpace(dpkgOut)) == 0 || err != nil {
-			logf("tun module not loaded nor found on disk")
-			return
-		}
-		if !bytes.Contains(dpkgOut, kernel) {
-			logf("kernel/drivers/net/tun.ko found on disk, but not for current kernel; are you in middle of a system update and haven't rebooted? found: %s", dpkgOut)
-		}
-	case distro.Arch:
-		findOut, err := exec.Command("find", "/lib/modules/", "-path", "*/net/tun.ko*").CombinedOutput()
-		if len(bytes.TrimSpace(findOut)) == 0 || err != nil {
-			logf("tun module not loaded nor found on disk")
-			return
-		}
-		if !bytes.Contains(findOut, kernel) {
-			logf("kernel/drivers/net/tun.ko found on disk, but not for current kernel; are you in middle of a system update and haven't rebooted? found: %s", findOut)
-		}
-	case distro.OpenWrt:
-		out, err := exec.Command("opkg", "list-installed").CombinedOutput()
-		if err != nil {
-			logf("error querying OpenWrt installed packages: %s", out)
-			return
-		}
-		for _, pkg := range []string{"kmod-tun", "ca-bundle"} {
-			if !bytes.Contains(out, []byte(pkg+" - ")) {
-				logf("Missing required package %s; run: opkg install %s", pkg, pkg)
-			}
-		}
-	}
-}

net/tstun/tun_linux.go

@@ -0,0 +1,96 @@
+// 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 tstun
+
+import (
+	"bytes"
+	"os"
+	"os/exec"
+	"strings"
+	"syscall"
+
+	"tailscale.com/types/logger"
+	"tailscale.com/version/distro"
+)
+
+func init() {
+	tunDiagnoseFailure = diagnoseLinuxTUNFailure
+}
+
+func diagnoseLinuxTUNFailure(tunName string, logf logger.Logf) {
+	var un syscall.Utsname
+	err := syscall.Uname(&un)
+	if err != nil {
+		logf("no TUN, and failed to look up kernel version: %v", err)
+		return
+	}
+	kernel := utsReleaseField(&un)
+	logf("Linux kernel version: %s", kernel)
+
+	modprobeOut, err := exec.Command("/sbin/modprobe", "tun").CombinedOutput()
+	if err == nil {
+		logf("'modprobe tun' successful")
+		// Either tun is currently loaded, or it's statically
+		// compiled into the kernel (which modprobe checks
+		// with /lib/modules/$(uname -r)/modules.builtin)
+		//
+		// So if there's a problem at this point, it's
+		// probably because /dev/net/tun doesn't exist.
+		const dev = "/dev/net/tun"
+		if fi, err := os.Stat(dev); err != nil {
+			logf("tun module loaded in kernel, but %s does not exist", dev)
+		} else {
+			logf("%s: %v", dev, fi.Mode())
+		}
+
+		// We failed to find why it failed. Just let our
+		// caller report the error it got from wireguard-go.
+		return
+	}
+	logf("is CONFIG_TUN enabled in your kernel? `modprobe tun` failed with: %s", modprobeOut)
+
+	switch distro.Get() {
+	case distro.Debian:
+		dpkgOut, err := exec.Command("dpkg", "-S", "kernel/drivers/net/tun.ko").CombinedOutput()
+		if len(bytes.TrimSpace(dpkgOut)) == 0 || err != nil {
+			logf("tun module not loaded nor found on disk")
+			return
+		}
+		if !bytes.Contains(dpkgOut, []byte(kernel)) {
+			logf("kernel/drivers/net/tun.ko found on disk, but not for current kernel; are you in middle of a system update and haven't rebooted? found: %s", dpkgOut)
+		}
+	case distro.Arch:
+		findOut, err := exec.Command("find", "/lib/modules/", "-path", "*/net/tun.ko*").CombinedOutput()
+		if len(bytes.TrimSpace(findOut)) == 0 || err != nil {
+			logf("tun module not loaded nor found on disk")
+			return
+		}
+		if !bytes.Contains(findOut, []byte(kernel)) {
+			logf("kernel/drivers/net/tun.ko found on disk, but not for current kernel; are you in middle of a system update and haven't rebooted? found: %s", findOut)
+		}
+	case distro.OpenWrt:
+		out, err := exec.Command("opkg", "list-installed").CombinedOutput()
+		if err != nil {
+			logf("error querying OpenWrt installed packages: %s", out)
+			return
+		}
+		for _, pkg := range []string{"kmod-tun", "ca-bundle"} {
+			if !bytes.Contains(out, []byte(pkg+" - ")) {
+				logf("Missing required package %s; run: opkg install %s", pkg, pkg)
+			}
+		}
+	}
+}
+
+func utsReleaseField(u *syscall.Utsname) string {
+	var sb strings.Builder
+	for _, v := range u.Release {
+		if v == 0 {
+			break
+		}
+		sb.WriteByte(byte(v))
+	}
+	return strings.TrimSpace(sb.String())
+}

net/tstun/tun_macos.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.
+
+//go:build darwin && !ios
+// +build darwin,!ios
+
+package tstun
+
+import (
+	"os"
+
+	"tailscale.com/types/logger"
+)
+
+func init() {
+	tunDiagnoseFailure = diagnoseDarwinTUNFailure
+}
+
+func diagnoseDarwinTUNFailure(tunName string, logf logger.Logf) {
+	if os.Getuid() != 0 {
+		logf("failed to create TUN device as non-root user; use 'sudo tailscaled', or run under launchd with 'sudo tailscaled install-system-daemon'")
+	}
+	if tunName != "utun" {
+		logf("failed to create TUN device %q; try using tun device \"utun\" instead for automatic selection", tunName)
+	}
+}

paths/migrate.go

@@ -0,0 +1,59 @@
+// 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 paths
+
+import (
+	"os"
+	"path/filepath"
+
+	"tailscale.com/types/logger"
+)
+
+// TryConfigFileMigration carefully copies the contents of oldFile to
+// newFile, returning the path which should be used to read the config.
+// - if newFile already exists, don't modify it just return its path
+// - if neither oldFile nor newFile exist, return newFile for a fresh
+//   default config to be written to.
+// - if oldFile exists but copying to newFile fails, return oldFile so
+//   there will at least be some config to work with.
+func TryConfigFileMigration(logf logger.Logf, oldFile, newFile string) string {
+	_, err := os.Stat(newFile)
+	if err == nil {
+		// Common case for a system which has already been migrated.
+		return newFile
+	}
+	if !os.IsNotExist(err) {
+		logf("TryConfigFileMigration failed; new file: %v", err)
+		return newFile
+	}
+
+	contents, err := os.ReadFile(oldFile)
+	if err != nil {
+		// Common case for a new user.
+		return newFile
+	}
+
+	if err = MkStateDir(filepath.Dir(newFile)); err != nil {
+		logf("TryConfigFileMigration failed; MkStateDir: %v", err)
+		return oldFile
+	}
+
+	err = os.WriteFile(newFile, contents, 0600)
+	if err != nil {
+		removeErr := os.Remove(newFile)
+		if removeErr != nil {
+			logf("TryConfigFileMigration failed; write newFile no cleanup: %v, remove err: %v",
+				err, removeErr)
+			return oldFile
+		}
+		logf("TryConfigFileMigration failed; write newFile: %v", err)
+		return oldFile
+	}
+
+	logf("TryConfigFileMigration: successfully migrated: from %v to %v",
+		oldFile, newFile)
+
+	return newFile
+}

paths/paths.go

@@ -55,7 +55,18 @@ func DefaultTailscaledStateFile() string {
 		return f()
 	}
 	if runtime.GOOS == "windows" {
-		return filepath.Join(os.Getenv("LocalAppData"), "Tailscale", "server-state.conf")
+		return filepath.Join(os.Getenv("ProgramData"), "Tailscale", "server-state.conf")
 	}
 	return ""
 }
+
+// MkStateDir ensures that dirPath, the daemon's configurtaion directory
+// containing machine keys etc, both exists and has the correct permissions.
+// We want it to only be accessible to the user the daemon is running under.
+func MkStateDir(dirPath string) error {
+	if err := os.MkdirAll(dirPath, 0700); err != nil {
+		return err
+	}
+
+	return ensureStateDirPerms(dirPath)
+}

paths/paths_unix.go

@@ -61,3 +61,11 @@ func xdgDataHome() string {
 	}
 	return filepath.Join(os.Getenv("HOME"), ".local/share")
 }
+
+func ensureStateDirPerms(dirPath string) error {
+	if filepath.Base(dirPath) != "tailscale" {
+		return nil
+	}
+
+	return os.Chmod(dirPath, 0700)
+}

paths/paths_windows.go

@@ -0,0 +1,150 @@
+// 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 paths
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"unsafe"
+
+	"golang.org/x/sys/windows"
+)
+
+func getTokenInfo(token windows.Token, infoClass uint32) ([]byte, error) {
+	var desiredLen uint32
+	err := windows.GetTokenInformation(token, infoClass, nil, 0, &desiredLen)
+	if err != nil && err != windows.ERROR_INSUFFICIENT_BUFFER {
+		return nil, err
+	}
+
+	buf := make([]byte, desiredLen)
+	actualLen := desiredLen
+	err = windows.GetTokenInformation(token, infoClass, &buf[0], desiredLen, &actualLen)
+	return buf, err
+}
+
+func getTokenUserInfo(token windows.Token) (*windows.Tokenuser, error) {
+	buf, err := getTokenInfo(token, windows.TokenUser)
+	if err != nil {
+		return nil, err
+	}
+
+	return (*windows.Tokenuser)(unsafe.Pointer(&buf[0])), nil
+}
+
+func getTokenPrimaryGroupInfo(token windows.Token) (*windows.Tokenprimarygroup, error) {
+	buf, err := getTokenInfo(token, windows.TokenPrimaryGroup)
+	if err != nil {
+		return nil, err
+	}
+
+	return (*windows.Tokenprimarygroup)(unsafe.Pointer(&buf[0])), nil
+}
+
+type userSids struct {
+	User         *windows.SID
+	PrimaryGroup *windows.SID
+}
+
+func getCurrentUserSids() (*userSids, error) {
+	token, err := windows.OpenCurrentProcessToken()
+	if err != nil {
+		return nil, err
+	}
+	defer token.Close()
+
+	userInfo, err := getTokenUserInfo(token)
+	if err != nil {
+		return nil, err
+	}
+
+	primaryGroup, err := getTokenPrimaryGroupInfo(token)
+	if err != nil {
+		return nil, err
+	}
+
+	return &userSids{userInfo.User.Sid, primaryGroup.PrimaryGroup}, nil
+}
+
+// ensureStateDirPerms applies a restrictive ACL to the directory specified by dirPath.
+// It sets the following security attributes on the directory:
+// Owner: The user for the current process;
+// Primary Group: The primary group for the current process;
+// DACL: Full control to the current user and to the Administrators group.
+//       (We include Administrators so that admin users may still access logs;
+//        granting access exclusively to LocalSystem would require admins to use
+//        special tools to access the Log directory)
+// Inheritance: The directory does not inherit the ACL from its parent.
+//              However, any directories and/or files created within this
+//              directory *do* inherit the ACL that we are setting.
+func ensureStateDirPerms(dirPath string) error {
+	fi, err := os.Stat(dirPath)
+	if err != nil {
+		return err
+	}
+	if !fi.IsDir() {
+		return os.ErrInvalid
+	}
+	if strings.ToLower(filepath.Base(dirPath)) != "tailscale" {
+		return nil
+	}
+
+	// We need the info for our current user as SIDs
+	sids, err := getCurrentUserSids()
+	if err != nil {
+		return err
+	}
+
+	// We also need the SID for the Administrators group so that admins may
+	// easily access logs.
+	adminGroupSid, err := windows.CreateWellKnownSid(windows.WinBuiltinAdministratorsSid)
+	if err != nil {
+		return err
+	}
+
+	// Munge the SIDs into the format required by EXPLICIT_ACCESS.
+	userTrustee := windows.TRUSTEE{nil, windows.NO_MULTIPLE_TRUSTEE,
+		windows.TRUSTEE_IS_SID, windows.TRUSTEE_IS_USER,
+		windows.TrusteeValueFromSID(sids.User)}
+
+	adminTrustee := windows.TRUSTEE{nil, windows.NO_MULTIPLE_TRUSTEE,
+		windows.TRUSTEE_IS_SID, windows.TRUSTEE_IS_WELL_KNOWN_GROUP,
+		windows.TrusteeValueFromSID(adminGroupSid)}
+
+	// We declare our access rights via this array of EXPLICIT_ACCESS structures.
+	// We set full access to our user and to Administrators.
+	// We configure the DACL such that any files or directories created within
+	// dirPath will also inherit this DACL.
+	explicitAccess := []windows.EXPLICIT_ACCESS{
+		windows.EXPLICIT_ACCESS{
+			windows.GENERIC_ALL,
+			windows.SET_ACCESS,
+			windows.SUB_CONTAINERS_AND_OBJECTS_INHERIT,
+			userTrustee,
+		},
+		windows.EXPLICIT_ACCESS{
+			windows.GENERIC_ALL,
+			windows.SET_ACCESS,
+			windows.SUB_CONTAINERS_AND_OBJECTS_INHERIT,
+			adminTrustee,
+		},
+	}
+
+	dacl, err := windows.ACLFromEntries(explicitAccess, nil)
+	if err != nil {
+		return err
+	}
+
+	// We now reset the file's owner, primary group, and DACL.
+	// We also must pass PROTECTED_DACL_SECURITY_INFORMATION so that our new ACL
+	// does not inherit any ACL entries from the parent directory.
+	const flags = windows.OWNER_SECURITY_INFORMATION |
+		windows.GROUP_SECURITY_INFORMATION |
+		windows.DACL_SECURITY_INFORMATION |
+		windows.PROTECTED_DACL_SECURITY_INFORMATION
+	return windows.SetNamedSecurityInfo(dirPath, windows.SE_FILE_OBJECT, flags,
+		sids.User, sids.PrimaryGroup, dacl, nil)
+}

portlist/netstat.go

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build (go1.16 && !ios) || (!go1.16 && !darwin) || (!go1.16 && !arm64)
-// +build go1.16,!ios !go1.16,!darwin !go1.16,!arm64
+//go:build !ios
+// +build !ios
 
 package portlist
 

portlist/netstat_exec.go

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build (windows || freebsd || openbsd || (darwin && go1.16) || (darwin && !go1.16 && !arm64)) && !ios
-// +build windows freebsd openbsd darwin,go1.16 darwin,!go1.16,!arm64
+//go:build (windows || freebsd || openbsd || darwin) && !ios
+// +build windows freebsd openbsd darwin
 // +build !ios
 
 package portlist

portlist/portlist_ios.go

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build (go1.16 && ios) || (!go1.16 && darwin && !amd64)
-// +build go1.16,ios !go1.16,darwin,!amd64
+//go:build ios
+// +build ios
 
 package portlist
 

portlist/portlist_macos.go

@@ -2,9 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build ((darwin && amd64 && !go1.16) || (darwin && go1.16)) && !ios
-// +build darwin,amd64,!go1.16 darwin,go1.16
-// +build !ios
+//go:build darwin && !ios
+// +build darwin,!ios
 
 package portlist
 

safesocket/safesocket.go

@@ -10,6 +10,7 @@ import (
 	"errors"
 	"net"
 	"runtime"
+	"time"
 )
 
 type closeable interface {
@@ -29,9 +30,39 @@ func ConnCloseWrite(c net.Conn) error {
 	return c.(closeable).CloseWrite()
 }
 
+var processStartTime = time.Now()
+var tailscaledProcExists = func() bool { return false } // set by safesocket_ps.go
+
+// tailscaledStillStarting reports whether tailscaled is probably
+// still starting up. That is, it reports whether the caller should
+// keep retrying to connect.
+func tailscaledStillStarting() bool {
+	d := time.Since(processStartTime)
+	if d < 2*time.Second {
+		// Without even checking the process table, assume
+		// that for the first two seconds that tailscaled is
+		// probably still starting.  That is, assume they're
+		// running "tailscaled & tailscale up ...." and make
+		// the tailscale client block for a bit for tailscaled
+		// to start accepting on the socket.
+		return true
+	}
+	if d > 5*time.Second {
+		return false
+	}
+	return tailscaledProcExists()
+}
+
 // Connect connects to either path (on Unix) or the provided localhost port (on Windows).
 func Connect(path string, port uint16) (net.Conn, error) {
-	return connect(path, port)
+	for {
+		c, err := connect(path, port)
+		if err != nil && tailscaledStillStarting() {
+			time.Sleep(250 * time.Millisecond)
+			continue
+		}
+		return c, err
+	}
 }
 
 // Listen returns a listener either on Unix socket path (on Unix), or

safesocket/safesocket_ps.go

@@ -0,0 +1,37 @@
+// 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.
+
+//go:build linux || windows || darwin || freebsd
+// +build linux windows darwin freebsd
+
+package safesocket
+
+import (
+	"strings"
+
+	ps "github.com/mitchellh/go-ps"
+)
+
+func init() {
+	tailscaledProcExists = func() bool {
+		procs, err := ps.Processes()
+		if err != nil {
+			return false
+		}
+		for _, proc := range procs {
+			name := proc.Executable()
+			const tailscaled = "tailscaled"
+			if len(name) < len(tailscaled) {
+				continue
+			}
+			// Do case insensitive comparison for Windows,
+			// notably, and ignore any ".exe" suffix.
+			if strings.EqualFold(name[:len(tailscaled)], tailscaled) {
+				return true
+			}
+		}
+		return false
+
+	}
+}

syncs/locked.go

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build go1.13 && !go1.16
-// +build go1.13,!go1.16
+//go:build go1.13 && !go1.18
+// +build go1.13,!go1.18
 
 // This file makes assumptions about the inner workings of sync.Mutex and sync.RWMutex.
 // This includes not just their memory layout but their invariants and functionality.

syncs/locked_test.go

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build go1.13 && !go1.16
-// +build go1.13,!go1.16
+//go:build go1.13 && !go1.18
+// +build go1.13,!go1.18
 
 package syncs
 

tailcfg/tailcfg.go

@@ -46,7 +46,8 @@ import (
 //    20: 2021-06-11: MapResponse.LastSeen used even less (https://github.com/tailscale/tailscale/issues/2107)
 //    21: 2021-06-15: added MapResponse.DNSConfig.CertDomains
 //    22: 2021-06-16: added MapResponse.DNSConfig.ExtraRecords
-const CurrentMapRequestVersion = 22
+//    23: 2021-08-25: DNSConfig.Routes values may be empty (for ExtraRecords support in 1.14.1+)
+const CurrentMapRequestVersion = 23
 
 type StableID string
 
@@ -407,7 +408,7 @@ type Hostinfo struct {
 	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")
 	Package       string             `json:",omitempty"` // Tailscale package to disambiguate ("choco", "appstore", etc; "" for unknown)
-	DeviceModel   string             `json:",omitempty"` // mobile phone model ("Pixel 3a", "iPhone 11 Pro")
+	DeviceModel   string             `json:",omitempty"` // mobile phone model ("Pixel 3a", "iPhone12,3")
 	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
@@ -837,12 +838,19 @@ var FilterAllowAll = []FilterRule{
 type DNSConfig struct {
 	// Resolvers are the DNS resolvers to use, in order of preference.
 	Resolvers []dnstype.Resolver `json:",omitempty"`
+
 	// Routes maps DNS name suffixes to a set of DNS resolvers to
 	// use. It is used to implement "split DNS" and other advanced DNS
 	// routing overlays.
-	// Map keys must be fully-qualified DNS name suffixes, with a
-	// trailing dot but no leading dot.
+	//
+	// Map keys are fully-qualified DNS name suffixes; they may
+	// optionally contain a trailing dot but no leading dot.
+	//
+	// If the value is an empty slice, that means the suffix should still
+	// be handled by Tailscale's built-in resolver (100.100.100.100), such
+	// as for the purpose of handling ExtraRecords.
 	Routes map[string][]dnstype.Resolver `json:",omitempty"`
+
 	// FallbackResolvers is like Resolvers, but is only used if a
 	// split DNS configuration is requested in a configuration that
 	// doesn't work yet without explicit default resolvers.
@@ -897,19 +905,30 @@ type DNSRecord struct {
 	Value string
 }
 
-// PingRequest is a request to send an HTTP request to prove the
+// PingRequest with no IP and Types is a request to send an HTTP request to prove the
 // long-polling client is still connected.
+// PingRequest with Types and IP, will send a ping to the IP and send a
+// POST request to the URL to prove that the ping succeeded.
 type PingRequest struct {
 	// URL is the URL to send a HEAD request to.
 	// It will be a unique URL each time. No auth headers are necessary.
 	//
 	// If the client sees multiple PingRequests with the same URL,
 	// subsequent ones should be ignored.
+	// If Types and IP are defined, then URL is the URL to send a POST request to.
 	URL string
 
 	// Log is whether to log about this ping in the success case.
 	// For failure cases, the client will log regardless.
 	Log bool `json:",omitempty"`
+
+	// Types is the types of ping that is initiated. Can be TSMP, ICMP or disco.
+	// Types will be comma separated, such as TSMP,disco.
+	Types string
+
+	// IP is the ping target.
+	// It is used in TSMP pings, if IP is invalid or empty then do a HEAD request to the URL.
+	IP netaddr.IP
 }
 
 type MapResponse struct {

tsnet/tsnet.go

@@ -177,11 +177,12 @@ func (s *Server) start() error {
 	err = lb.Start(ipn.Options{
 		StateKey:    ipn.GlobalDaemonStateKey,
 		UpdatePrefs: prefs,
+		AuthKey:     os.Getenv("TS_AUTHKEY"),
 	})
 	if err != nil {
 		return fmt.Errorf("starting backend: %w", err)
 	}
-	if os.Getenv("TS_LOGIN") == "1" {
+	if os.Getenv("TS_LOGIN") == "1" || os.Getenv("TS_AUTHKEY") != "" {
 		s.lb.StartLoginInteractive()
 	}
 	return nil

tstest/integration/testcontrol/testcontrol.go

@@ -31,6 +31,7 @@ import (
 	"tailscale.com/net/tsaddr"
 	"tailscale.com/smallzstd"
 	"tailscale.com/tailcfg"
+	"tailscale.com/types/key"
 	"tailscale.com/types/logger"
 	"tailscale.com/types/wgkey"
 )
@@ -269,6 +270,33 @@ func (s *Server) nodeLocked(nodeKey tailcfg.NodeKey) *tailcfg.Node {
 	return s.nodes[nodeKey].Clone()
 }
 
+// AddFakeNode injects a fake node into the server.
+func (s *Server) AddFakeNode() {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if s.nodes == nil {
+		s.nodes = make(map[tailcfg.NodeKey]*tailcfg.Node)
+	}
+	nk := tailcfg.NodeKey(key.NewPrivate().Public())
+	mk := tailcfg.MachineKey(key.NewPrivate().Public())
+	dk := tailcfg.DiscoKey(key.NewPrivate().Public())
+	id := int64(binary.LittleEndian.Uint64(nk[:]))
+	ip := netaddr.IPv4(nk[0], nk[1], nk[2], nk[3])
+	addr := netaddr.IPPrefixFrom(ip, 32)
+	s.nodes[nk] = &tailcfg.Node{
+		ID:                tailcfg.NodeID(id),
+		StableID:          tailcfg.StableNodeID(fmt.Sprintf("TESTCTRL%08x", id)),
+		User:              tailcfg.UserID(id),
+		Machine:           mk,
+		Key:               nk,
+		MachineAuthorized: true,
+		DiscoKey:          dk,
+		Addresses:         []netaddr.IPPrefix{addr},
+		AllowedIPs:        []netaddr.IPPrefix{addr},
+	}
+	// TODO: send updates to other (non-fake?) nodes
+}
+
 func (s *Server) AllNodes() (nodes []*tailcfg.Node) {
 	s.mu.Lock()
 	defer s.mu.Unlock()
@@ -661,6 +689,9 @@ func (s *Server) MapResponse(req *tailcfg.MapRequest) (res *tailcfg.MapResponse,
 			res.Peers = append(res.Peers, p)
 		}
 	}
+	sort.Slice(res.Peers, func(i, j int) bool {
+		return res.Peers[i].ID < res.Peers[j].ID
+	})
 
 	v4Prefix := netaddr.IPPrefixFrom(netaddr.IPv4(100, 64, uint8(tailcfg.NodeID(user.ID)>>8), uint8(tailcfg.NodeID(user.ID))), 32)
 	v6Prefix := netaddr.IPPrefixFrom(tsaddr.Tailscale4To6(v4Prefix.IP()), 128)

tstime/rate/rate_test.go

@@ -182,15 +182,18 @@ func TestLongRunningQPS(t *testing.T) {
 		wg.Done()
 	}
 
+	// This will still offer ~500 requests per second,
+	// but won't consume outrageous amount of CPU.
 	start := time.Now()
 	end := start.Add(5 * time.Second)
-	for time.Now().Before(end) {
+	ticker := time.NewTicker(2 * time.Millisecond)
+	defer ticker.Stop()
+	for now := range ticker.C {
+		if now.After(end) {
+			break
+		}
 		wg.Add(1)
 		go f()
-
-		// This will still offer ~500 requests per second, but won't consume
-		// outrageous amount of CPU.
-		time.Sleep(2 * time.Millisecond)
 	}
 	wg.Wait()
 	elapsed := time.Since(start)
@@ -201,7 +204,7 @@ func TestLongRunningQPS(t *testing.T) {
 		t.Errorf("numOK = %d, want %d (ideal %f)", numOK, want, ideal)
 	}
 	// We should get very close to the number of requests allowed.
-	if want := int32(0.999 * ideal); numOK < want {
+	if want := int32(0.995 * ideal); numOK < want {
 		t.Errorf("numOK = %d, want %d (ideal %f)", numOK, want, ideal)
 	}
 }

tsweb/tsweb.go

@@ -19,6 +19,7 @@ import (
 	_ "net/http/pprof"
 	"os"
 	"path/filepath"
+	"reflect"
 	"runtime"
 	"strings"
 	"time"
@@ -27,9 +28,12 @@ import (
 	"tailscale.com/metrics"
 	"tailscale.com/net/tsaddr"
 	"tailscale.com/types/logger"
+	"tailscale.com/version"
 )
 
 func init() {
+	expvar.Publish("process_start_unix_time", expvar.Func(func() interface{} { return timeStart.Unix() }))
+	expvar.Publish("version", expvar.Func(func() interface{} { return version.Long }))
 	expvar.Publish("counter_uptime_sec", expvar.Func(func() interface{} { return int64(Uptime().Seconds()) }))
 	expvar.Publish("gauge_goroutines", expvar.Func(func() interface{} { return runtime.NumGoroutine() }))
 }
@@ -342,6 +346,141 @@ func Error(code int, msg string, err error) HTTPError {
 	return HTTPError{Code: code, Msg: msg, Err: err}
 }
 
+// WritePrometheusExpvar writes kv to w in Prometheus metrics format.
+//
+// See VarzHandler for conventions. This is exported primarily for
+// people to test their varz.
+func WritePrometheusExpvar(w io.Writer, kv expvar.KeyValue) {
+	writePromExpVar(w, "", kv)
+}
+
+func writePromExpVar(w io.Writer, prefix string, kv expvar.KeyValue) {
+	key := kv.Key
+	var typ string
+	var label string
+	switch {
+	case strings.HasPrefix(kv.Key, "gauge_"):
+		typ = "gauge"
+		key = strings.TrimPrefix(kv.Key, "gauge_")
+
+	case strings.HasPrefix(kv.Key, "counter_"):
+		typ = "counter"
+		key = strings.TrimPrefix(kv.Key, "counter_")
+	}
+	if strings.HasPrefix(key, "labelmap_") {
+		key = strings.TrimPrefix(key, "labelmap_")
+		if i := strings.Index(key, "_"); i != -1 {
+			label, key = key[:i], key[i+1:]
+		}
+	}
+	name := prefix + key
+
+	switch v := kv.Value.(type) {
+	case *expvar.Int:
+		if typ == "" {
+			typ = "counter"
+		}
+		fmt.Fprintf(w, "# TYPE %s %s\n%s %v\n", name, typ, name, v.Value())
+		return
+	case *metrics.Set:
+		v.Do(func(kv expvar.KeyValue) {
+			writePromExpVar(w, name+"_", kv)
+		})
+		return
+	case PrometheusMetricsReflectRooter:
+		root := v.PrometheusMetricsReflectRoot()
+		rv := reflect.ValueOf(root)
+		if rv.Type().Kind() == reflect.Ptr {
+			if rv.IsNil() {
+				return
+			}
+			rv = rv.Elem()
+		}
+		if rv.Type().Kind() != reflect.Struct {
+			fmt.Fprintf(w, "# skipping expvar %q; unknown root type\n", name)
+			return
+		}
+		foreachExportedStructField(rv, func(fieldOrJSONName, metricType string, rv reflect.Value) {
+			mname := name + "_" + fieldOrJSONName
+			switch rv.Kind() {
+			case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+				fmt.Fprintf(w, "# TYPE %s %s\n%s %v\n", mname, metricType, mname, rv.Int())
+			case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+				fmt.Fprintf(w, "# TYPE %s %s\n%s %v\n", mname, metricType, mname, rv.Uint())
+			case reflect.Float32, reflect.Float64:
+				fmt.Fprintf(w, "# TYPE %s %s\n%s %v\n", mname, metricType, mname, rv.Float())
+			case reflect.Struct:
+				if rv.CanAddr() {
+					// Slight optimization, not copying big structs if they're addressable:
+					writePromExpVar(w, name+"_", expvar.KeyValue{Key: fieldOrJSONName, Value: expVarPromStructRoot{rv.Addr().Interface()}})
+				} else {
+					writePromExpVar(w, name+"_", expvar.KeyValue{Key: fieldOrJSONName, Value: expVarPromStructRoot{rv.Interface()}})
+				}
+			}
+			return
+		})
+		return
+	}
+
+	if typ == "" {
+		var funcRet string
+		if f, ok := kv.Value.(expvar.Func); ok {
+			v := f()
+			if ms, ok := v.(runtime.MemStats); ok && name == "memstats" {
+				writeMemstats(w, &ms)
+				return
+			}
+			switch v := v.(type) {
+			case int, int8, int16, int32, int64, uint, uint8, uint16, uint32, uint64, uintptr, float32, float64:
+				fmt.Fprintf(w, "%s %v\n", name, v)
+				return
+			}
+			funcRet = fmt.Sprintf(" returning %T", v)
+		}
+		switch kv.Value.(type) {
+		default:
+			fmt.Fprintf(w, "# skipping expvar %q (Go type %T%s) with undeclared Prometheus type\n", name, kv.Value, funcRet)
+			return
+		case *metrics.LabelMap, *expvar.Map:
+			// Permit typeless LabelMap and expvar.Map for
+			// compatibility with old expvar-registered
+			// metrics.LabelMap.
+		}
+	}
+
+	switch v := kv.Value.(type) {
+	case expvar.Func:
+		val := v()
+		switch val.(type) {
+		case float64, int64, int:
+			fmt.Fprintf(w, "# TYPE %s %s\n%s %v\n", name, typ, name, val)
+		default:
+			fmt.Fprintf(w, "# skipping expvar func %q returning unknown type %T\n", name, val)
+		}
+
+	case *metrics.LabelMap:
+		if typ != "" {
+			fmt.Fprintf(w, "# TYPE %s %s\n", name, typ)
+		}
+		// IntMap uses expvar.Map on the inside, which presorts
+		// keys. The output ordering is deterministic.
+		v.Do(func(kv expvar.KeyValue) {
+			fmt.Fprintf(w, "%s{%s=%q} %v\n", name, v.Label, kv.Key, kv.Value)
+		})
+	case *expvar.Map:
+		if label != "" && typ != "" {
+			fmt.Fprintf(w, "# TYPE %s %s\n", name, typ)
+			v.Do(func(kv expvar.KeyValue) {
+				fmt.Fprintf(w, "%s{%s=%q} %v\n", name, label, kv.Key, kv.Value)
+			})
+		} else {
+			v.Do(func(kv expvar.KeyValue) {
+				fmt.Fprintf(w, "%s_%s %v\n", name, kv.Key, kv.Value)
+			})
+		}
+	}
+}
+
 // VarzHandler is an HTTP handler to write expvar values into the
 // prometheus export format:
 //
@@ -361,74 +500,23 @@ func Error(code int, msg string, err error) HTTPError {
 // This will evolve over time, or perhaps be replaced.
 func VarzHandler(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Content-Type", "text/plain; version=0.0.4")
-
-	var dump func(prefix string, kv expvar.KeyValue)
-	dump = func(prefix string, kv expvar.KeyValue) {
-		name := prefix + kv.Key
-
-		var typ string
-		switch {
-		case strings.HasPrefix(kv.Key, "gauge_"):
-			typ = "gauge"
-			name = prefix + strings.TrimPrefix(kv.Key, "gauge_")
-
-		case strings.HasPrefix(kv.Key, "counter_"):
-			typ = "counter"
-			name = prefix + strings.TrimPrefix(kv.Key, "counter_")
-		}
-
-		switch v := kv.Value.(type) {
-		case *expvar.Int:
-			if typ == "" {
-				typ = "counter"
-			}
-			fmt.Fprintf(w, "# TYPE %s %s\n%s %v\n", name, typ, name, v.Value())
-			return
-		case *metrics.Set:
-			v.Do(func(kv expvar.KeyValue) {
-				dump(name+"_", kv)
-			})
-			return
-		}
-
-		if typ == "" {
-			var funcRet string
-			if f, ok := kv.Value.(expvar.Func); ok {
-				v := f()
-				if ms, ok := v.(runtime.MemStats); ok && name == "memstats" {
-					writeMemstats(w, &ms)
-					return
-				}
-				funcRet = fmt.Sprintf(" returning %T", v)
-			}
-			fmt.Fprintf(w, "# skipping expvar %q (Go type %T%s) with undeclared Prometheus type\n", name, kv.Value, funcRet)
-			return
-		}
-
-		switch v := kv.Value.(type) {
-		case expvar.Func:
-			val := v()
-			switch val.(type) {
-			case float64, int64, int:
-				fmt.Fprintf(w, "# TYPE %s %s\n%s %v\n", name, typ, name, val)
-			default:
-				fmt.Fprintf(w, "# skipping expvar func %q returning unknown type %T\n", name, val)
-			}
-
-		case *metrics.LabelMap:
-			fmt.Fprintf(w, "# TYPE %s %s\n", name, typ)
-			// IntMap uses expvar.Map on the inside, which presorts
-			// keys. The output ordering is deterministic.
-			v.Do(func(kv expvar.KeyValue) {
-				fmt.Fprintf(w, "%s{%s=%q} %v\n", name, v.Label, kv.Key, kv.Value)
-			})
-		}
-	}
-	expvar.Do(func(kv expvar.KeyValue) {
-		dump("", kv)
+	expvarDo(func(kv expvar.KeyValue) {
+		writePromExpVar(w, "", kv)
 	})
 }
 
+// PrometheusMetricsReflectRooter is an optional interface that expvar.Var implementations
+// can implement to indicate that they should be walked recursively with reflect to find
+// sets of fields to export.
+type PrometheusMetricsReflectRooter interface {
+	expvar.Var
+
+	// PrometheusMetricsReflectRoot returns the struct or struct pointer to walk.
+	PrometheusMetricsReflectRoot() interface{}
+}
+
+var expvarDo = expvar.Do // pulled out for tests
+
 func writeMemstats(w io.Writer, ms *runtime.MemStats) {
 	out := func(name, typ string, v uint64, help string) {
 		if help != "" {
@@ -445,3 +533,42 @@ func writeMemstats(w io.Writer, ms *runtime.MemStats) {
 	c("frees", ms.Frees, "cumulative count of heap objects freed")
 	c("num_gc", uint64(ms.NumGC), "number of completed GC cycles")
 }
+
+func foreachExportedStructField(rv reflect.Value, f func(fieldOrJSONName, metricType string, rv reflect.Value)) {
+	t := rv.Type()
+	for i, n := 0, t.NumField(); i < n; i++ {
+		sf := t.Field(i)
+		name := sf.Name
+		if v := sf.Tag.Get("json"); v != "" {
+			if i := strings.Index(v, ","); i != -1 {
+				v = v[:i]
+			}
+			if v == "-" {
+				// Skip it, regardless of its metrictype.
+				continue
+			}
+			if v != "" {
+				name = v
+			}
+		}
+		metricType := sf.Tag.Get("metrictype")
+		if metricType != "" || sf.Type.Kind() == reflect.Struct {
+			f(name, metricType, rv.Field(i))
+		} else if sf.Type.Kind() == reflect.Ptr && sf.Type.Elem().Kind() == reflect.Struct {
+			fv := rv.Field(i)
+			if !fv.IsNil() {
+				f(name, metricType, fv.Elem())
+			}
+		}
+	}
+}
+
+type expVarPromStructRoot struct{ v interface{} }
+
+func (r expVarPromStructRoot) PrometheusMetricsReflectRoot() interface{} { return r.v }
+func (r expVarPromStructRoot) String() string                            { panic("unused") }
+
+var (
+	_ PrometheusMetricsReflectRooter = expVarPromStructRoot{}
+	_ expvar.Var                     = expVarPromStructRoot{}
+)

tsweb/tsweb_test.go

@@ -8,13 +8,16 @@ import (
 	"bufio"
 	"context"
 	"errors"
+	"expvar"
 	"net"
 	"net/http"
 	"net/http/httptest"
+	"strings"
 	"testing"
 	"time"
 
 	"github.com/google/go-cmp/cmp"
+	"tailscale.com/metrics"
 	"tailscale.com/tstest"
 )
 
@@ -300,3 +303,234 @@ func BenchmarkLog(b *testing.B) {
 		h.ServeHTTP(rw, req)
 	}
 }
+
+func TestVarzHandler(t *testing.T) {
+	t.Run("globals_log", func(t *testing.T) {
+		rec := httptest.NewRecorder()
+		VarzHandler(rec, httptest.NewRequest("GET", "/", nil))
+		t.Logf("Got: %s", rec.Body.Bytes())
+	})
+
+	tests := []struct {
+		name string
+		k    string // key name
+		v    expvar.Var
+		want string
+	}{
+		{
+			"int",
+			"foo",
+			new(expvar.Int),
+			"# TYPE foo counter\nfoo 0\n",
+		},
+		{
+			"int_with_type_counter",
+			"counter_foo",
+			new(expvar.Int),
+			"# TYPE foo counter\nfoo 0\n",
+		},
+		{
+			"int_with_type_gauge",
+			"gauge_foo",
+			new(expvar.Int),
+			"# TYPE foo gauge\nfoo 0\n",
+		},
+		{
+			"metrics_set",
+			"s",
+			&metrics.Set{
+				Map: *(func() *expvar.Map {
+					m := new(expvar.Map)
+					m.Init()
+					m.Add("foo", 1)
+					m.Add("bar", 2)
+					return m
+				})(),
+			},
+			"# TYPE s_bar counter\ns_bar 2\n# TYPE s_foo counter\ns_foo 1\n",
+		},
+		{
+			"metrics_set_TODO_gauge_type",
+			"gauge_s", // TODO(bradfitz): arguably a bug; should pass down type
+			&metrics.Set{
+				Map: *(func() *expvar.Map {
+					m := new(expvar.Map)
+					m.Init()
+					m.Add("foo", 1)
+					m.Add("bar", 2)
+					return m
+				})(),
+			},
+			"# TYPE s_bar counter\ns_bar 2\n# TYPE s_foo counter\ns_foo 1\n",
+		},
+		{
+			"expvar_map_untyped",
+			"api_status_code",
+			func() *expvar.Map {
+				m := new(expvar.Map)
+				m.Init()
+				m.Add("2xx", 100)
+				m.Add("5xx", 2)
+				return m
+			}(),
+			"api_status_code_2xx 100\napi_status_code_5xx 2\n",
+		},
+		{
+			"func_float64",
+			"counter_x",
+			expvar.Func(func() interface{} { return float64(1.2) }),
+			"# TYPE x counter\nx 1.2\n",
+		},
+		{
+			"func_float64_gauge",
+			"gauge_x",
+			expvar.Func(func() interface{} { return float64(1.2) }),
+			"# TYPE x gauge\nx 1.2\n",
+		},
+		{
+			"func_float64_untyped",
+			"x",
+			expvar.Func(func() interface{} { return float64(1.2) }),
+			"x 1.2\n",
+		},
+		{
+			"metrics_label_map",
+			"counter_m",
+			&metrics.LabelMap{
+				Label: "label",
+				Map: *(func() *expvar.Map {
+					m := new(expvar.Map)
+					m.Init()
+					m.Add("foo", 1)
+					m.Add("bar", 2)
+					return m
+				})(),
+			},
+			"# TYPE m counter\nm{label=\"bar\"} 2\nm{label=\"foo\"} 1\n",
+		},
+		{
+			"metrics_label_map_untyped",
+			"control_save_config",
+			(func() *metrics.LabelMap {
+				m := &metrics.LabelMap{Label: "reason"}
+				m.Add("new", 1)
+				m.Add("updated", 1)
+				m.Add("fun", 1)
+				return m
+			})(),
+			"control_save_config{reason=\"fun\"} 1\ncontrol_save_config{reason=\"new\"} 1\ncontrol_save_config{reason=\"updated\"} 1\n",
+		},
+		{
+			"expvar_label_map",
+			"counter_labelmap_keyname_m",
+			func() *expvar.Map {
+				m := new(expvar.Map)
+				m.Init()
+				m.Add("foo", 1)
+				m.Add("bar", 2)
+				return m
+			}(),
+			"# TYPE m counter\nm{keyname=\"bar\"} 2\nm{keyname=\"foo\"} 1\n",
+		},
+		{
+			"struct_reflect",
+			"foo",
+			someExpVarWithJSONAndPromTypes(),
+			strings.TrimSpace(`
+# TYPE foo_nestvalue_foo gauge
+foo_nestvalue_foo 1
+# TYPE foo_nestvalue_bar counter
+foo_nestvalue_bar 2
+# TYPE foo_nestptr_foo gauge
+foo_nestptr_foo 10
+# TYPE foo_nestptr_bar counter
+foo_nestptr_bar 20
+# TYPE foo_curX gauge
+foo_curX 3
+# TYPE foo_totalY counter
+foo_totalY 4
+# TYPE foo_curTemp gauge
+foo_curTemp 20.6
+# TYPE foo_AnInt8 counter
+foo_AnInt8 127
+# TYPE foo_AUint16 counter
+foo_AUint16 65535
+`) + "\n",
+		},
+		{
+			"struct_reflect_nil_root",
+			"foo",
+			expvarAdapter{(*SomeStats)(nil)},
+			"",
+		},
+		{
+			"func_returning_int",
+			"num_goroutines",
+			expvar.Func(func() interface{} { return 123 }),
+			"num_goroutines 123\n",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			defer func() { expvarDo = expvar.Do }()
+			expvarDo = func(f func(expvar.KeyValue)) {
+				f(expvar.KeyValue{Key: tt.k, Value: tt.v})
+			}
+			rec := httptest.NewRecorder()
+			VarzHandler(rec, httptest.NewRequest("GET", "/", nil))
+			if got := rec.Body.Bytes(); string(got) != tt.want {
+				t.Errorf("mismatch\n got: %q\n%s\nwant: %q\n%s\n", got, got, tt.want, tt.want)
+			}
+		})
+	}
+}
+
+type SomeNested struct {
+	FooG int64 `json:"foo" metrictype:"gauge"`
+	BarC int64 `json:"bar" metrictype:"counter"`
+	Omit int   `json:"-" metrictype:"counter"`
+}
+
+type SomeStats struct {
+	Nested       SomeNested  `json:"nestvalue"`
+	NestedPtr    *SomeNested `json:"nestptr"`
+	NestedNilPtr *SomeNested `json:"nestnilptr"`
+	CurX         int         `json:"curX" metrictype:"gauge"`
+	NoMetricType int         `json:"noMetric" metrictype:""`
+	TotalY       int64       `json:"totalY,omitempty" metrictype:"counter"`
+	CurTemp      float64     `json:"curTemp" metrictype:"gauge"`
+	AnInt8       int8        `metrictype:"counter"`
+	AUint16      uint16      `metrictype:"counter"`
+}
+
+// someExpVarWithJSONAndPromTypes returns an expvar.Var that
+// implements PrometheusMetricsReflectRooter for TestVarzHandler.
+func someExpVarWithJSONAndPromTypes() expvar.Var {
+	st := &SomeStats{
+		Nested: SomeNested{
+			FooG: 1,
+			BarC: 2,
+			Omit: 3,
+		},
+		NestedPtr: &SomeNested{
+			FooG: 10,
+			BarC: 20,
+		},
+		CurX:    3,
+		TotalY:  4,
+		CurTemp: 20.6,
+		AnInt8:  127,
+		AUint16: 65535,
+	}
+	return expvarAdapter{st}
+}
+
+type expvarAdapter struct {
+	st *SomeStats
+}
+
+func (expvarAdapter) String() string { return "{}" } // expvar JSON; unused in test
+
+func (a expvarAdapter) PrometheusMetricsReflectRoot() interface{} {
+	return a.st
+}

types/netmap/netmap.go

@@ -87,6 +87,12 @@ func (nm *NetworkMap) Concise() string {
 	return buf.String()
 }
 
+func (nm *NetworkMap) VeryConcise() string {
+	buf := new(strings.Builder)
+	nm.printConciseHeader(buf)
+	return buf.String()
+}
+
 // printConciseHeader prints a concise header line representing nm to buf.
 //
 // If this function is changed to access different fields of nm, keep
@@ -132,7 +138,7 @@ func (a *NetworkMap) equalConciseHeader(b *NetworkMap) bool {
 	return (a.Debug == nil && b.Debug == nil) || reflect.DeepEqual(a.Debug, b.Debug)
 }
 
-// printPeerConcise appends to buf a line repsenting the peer p.
+// printPeerConcise appends to buf a line representing the peer p.
 //
 // If this function is changed to access different fields of p, keep
 // in nodeConciseEqual in sync.

util/deephash/deephash_test.go

@@ -8,9 +8,11 @@ import (
 	"archive/tar"
 	"bufio"
 	"bytes"
+	"crypto/sha256"
 	"fmt"
 	"math"
 	"reflect"
+	"runtime"
 	"testing"
 
 	"inet.af/netaddr"
@@ -332,15 +334,32 @@ func TestArrayAllocs(t *testing.T) {
 	if version.IsRace() {
 		t.Skip("skipping test under race detector")
 	}
+
+	// In theory, there should be no allocations. However, escape analysis on
+	// certain architectures fails to detect that certain cases do not escape.
+	// This discrepency currently affects sha256.digest.Sum.
+	// Measure the number of allocations in sha256 to ensure that Hash does
+	// not allocate on top of its usage of sha256.
+	// See https://golang.org/issue/48055.
+	var b []byte
+	h := sha256.New()
+	want := int(testing.AllocsPerRun(1000, func() {
+		b = h.Sum(b[:0])
+	}))
+	switch runtime.GOARCH {
+	case "amd64", "arm64":
+		want = 0 // ensure no allocations on popular architectures
+	}
+
 	type T struct {
 		X [32]byte
 	}
 	x := &T{X: [32]byte{1: 1, 2: 2, 3: 3, 4: 4}}
-	n := int(testing.AllocsPerRun(1000, func() {
+	got := int(testing.AllocsPerRun(1000, func() {
 		sink = Hash(x)
 	}))
-	if n > 0 {
-		t.Errorf("allocs = %v; want 0", n)
+	if got > want {
+		t.Errorf("allocs = %v; want %v", got, want)
 	}
 }
 

version/cmdname.go

@@ -2,18 +2,20 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build (go1.16 && !ios) || (!go1.16 && !darwin) || (!go1.16 && !arm64)
-// +build go1.16,!ios !go1.16,!darwin !go1.16,!arm64
+//go:build !ios
+// +build !ios
 
 package version
 
 import (
+	"bytes"
+	"encoding/hex"
+	"errors"
+	"io"
 	"os"
 	"path"
 	"path/filepath"
 	"strings"
-
-	"rsc.io/goversion/version"
 )
 
 // CmdName returns either the base name of the current binary
@@ -30,13 +32,13 @@ func CmdName() string {
 	fallbackName := filepath.Base(strings.TrimSuffix(strings.ToLower(e), ".exe"))
 
 	var ret string
-	v, err := version.ReadExe(e)
+	info, err := findModuleInfo(e)
 	if err != nil {
 		return fallbackName
 	}
 	// v is like:
 	// "path\ttailscale.com/cmd/tailscale\nmod\ttailscale.com\t(devel)\t\ndep\tgithub.com/apenwarr/fixconsole\tv0.0.0-20191012055117-5a9f6489cc29\th1:muXWUcay7DDy1/hEQWrYlBy+g0EuwT70sBHg65SeUc4=\ndep\tgithub....
-	for _, line := range strings.Split(v.ModuleInfo, "\n") {
+	for _, line := range strings.Split(info, "\n") {
 		if strings.HasPrefix(line, "path\t") {
 			goPkg := strings.TrimPrefix(line, "path\t") // like "tailscale.com/cmd/tailscale"
 			ret = path.Base(goPkg)                      // goPkg is always forward slashes; use path, not filepath
@@ -48,3 +50,84 @@ func CmdName() string {
 	}
 	return ret
 }
+
+// findModuleInfo returns the Go module info from the executable file.
+func findModuleInfo(file string) (s string, err error) {
+	f, err := os.Open(file)
+	if err != nil {
+		return "", err
+	}
+	defer f.Close()
+	// Scan through f until we find infoStart.
+	buf := make([]byte, 65536)
+	start, err := findOffset(f, buf, infoStart)
+	if err != nil {
+		return "", err
+	}
+	start += int64(len(infoStart))
+	// Seek to the end of infoStart and scan for infoEnd.
+	_, err = f.Seek(start, io.SeekStart)
+	if err != nil {
+		return "", err
+	}
+	end, err := findOffset(f, buf, infoEnd)
+	if err != nil {
+		return "", err
+	}
+	length := end - start
+	// As of Aug 2021, tailscaled's mod info was about 2k.
+	if length > int64(len(buf)) {
+		return "", errors.New("mod info too large")
+	}
+	// We have located modinfo. Read it into buf.
+	buf = buf[:length]
+	_, err = f.Seek(start, io.SeekStart)
+	if err != nil {
+		return "", err
+	}
+	_, err = io.ReadFull(f, buf)
+	if err != nil {
+		return "", err
+	}
+	return string(buf), nil
+}
+
+// findOffset finds the absolute offset of needle in f,
+// starting at f's current read position,
+// using temporary buffer buf.
+func findOffset(f *os.File, buf, needle []byte) (int64, error) {
+	for {
+		// Fill buf and look within it.
+		n, err := f.Read(buf)
+		if err != nil {
+			return -1, err
+		}
+		i := bytes.Index(buf[:n], needle)
+		if i < 0 {
+			// Not found. Rewind a little bit in case we happened to end halfway through needle.
+			rewind, err := f.Seek(int64(-len(needle)), io.SeekCurrent)
+			if err != nil {
+				return -1, err
+			}
+			// If we're at EOF and rewound exactly len(needle) bytes, return io.EOF.
+			_, err = f.ReadAt(buf[:1], rewind+int64(len(needle)))
+			if err == io.EOF {
+				return -1, err
+			}
+			continue
+		}
+		// Found! Figure out exactly where.
+		cur, err := f.Seek(0, io.SeekCurrent)
+		if err != nil {
+			return -1, err
+		}
+		return cur - int64(n) + int64(i), nil
+	}
+}
+
+// These constants are taken from rsc.io/goversion.
+
+var (
+	infoStart, _ = hex.DecodeString("3077af0c9274080241e1c107e6d618e6")
+	infoEnd, _   = hex.DecodeString("f932433186182072008242104116d8f2")
+)

version/cmdname_ios.go

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build (go1.16 && ios) || (!go1.16 && darwin && arm64)
-// +build go1.16,ios !go1.16,darwin,arm64
+//go:build ios
+// +build ios
 
 package version
 

version/modinfo_test.go

@@ -0,0 +1,29 @@
+// 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 version
+
+import (
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestFindModuleInfo(t *testing.T) {
+	dir := t.TempDir()
+	name := filepath.Join(dir, "tailscaled-version-test")
+	out, err := exec.Command("go", "build", "-o", name, "tailscale.com/cmd/tailscaled").CombinedOutput()
+	if err != nil {
+		t.Fatalf("failed to build tailscaled: %v\n%s", err, out)
+	}
+	modinfo, err := findModuleInfo(name)
+	if err != nil {
+		t.Fatal(err)
+	}
+	prefix := "path\ttailscale.com/cmd/tailscaled\nmod\ttailscale.com"
+	if !strings.HasPrefix(modinfo, prefix) {
+		t.Errorf("unexpected modinfo contents %q", modinfo)
+	}
+}

version/version.go

@@ -8,7 +8,7 @@ package version
 // Long is a full version number for this build, of the form
 // "x.y.z-commithash", or "date.yyyymmdd" if no actual version was
 // provided.
-var Long = "date.20210727"
+var Long = "date.20210823"
 
 // Short is a short version number for this build, of the form
 // "x.y.z", or "date.yyyymmdd" if no actual version was provided.

wgengine/magicsock/debugknobs.go

@@ -0,0 +1,53 @@
+// 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.
+
+//go:build !ios
+// +build !ios
+
+package magicsock
+
+import (
+	"os"
+	"strconv"
+)
+
+// Various debugging and experimental tweakables, set by environment
+// variable.
+var (
+	// logPacketDests prints the known addresses for a peer every time
+	// they change, in the legacy (non-discovery) endpoint code only.
+	logPacketDests, _ = strconv.ParseBool(os.Getenv("TS_DEBUG_LOG_PACKET_DESTS"))
+	// debugDisco prints verbose logs of active discovery events as
+	// they happen.
+	debugDisco, _ = strconv.ParseBool(os.Getenv("TS_DEBUG_DISCO"))
+	// debugOmitLocalAddresses removes all local interface addresses
+	// from magicsock's discovered local endpoints. Used in some tests.
+	debugOmitLocalAddresses, _ = strconv.ParseBool(os.Getenv("TS_DEBUG_OMIT_LOCAL_ADDRS"))
+	// debugUseDerpRoute temporarily (2020-03-22) controls whether DERP
+	// reverse routing is enabled (Issue 150). It will become always true
+	// later.
+	debugUseDerpRouteEnv = os.Getenv("TS_DEBUG_ENABLE_DERP_ROUTE")
+	debugUseDerpRoute, _ = strconv.ParseBool(debugUseDerpRouteEnv)
+	// logDerpVerbose logs all received DERP packets, including their
+	// full payload.
+	logDerpVerbose, _ = strconv.ParseBool(os.Getenv("TS_DEBUG_DERP"))
+	// debugReSTUNStopOnIdle unconditionally enables the "shut down
+	// STUN if magicsock is idle" behavior that normally only triggers
+	// on mobile devices, lowers the shutdown interval, and logs more
+	// verbosely about idle measurements.
+	debugReSTUNStopOnIdle, _ = strconv.ParseBool(os.Getenv("TS_DEBUG_RESTUN_STOP_ON_IDLE"))
+	// debugAlwaysDERP disables the use of UDP, forcing all peer communication over DERP.
+	debugAlwaysDERP, _ = strconv.ParseBool(os.Getenv("TS_DEBUG_ALWAYS_USE_DERP"))
+)
+
+// inTest reports whether the running program is a test that set the
+// IN_TS_TEST environment variable.
+//
+// Unlike the other debug tweakables above, this one needs to be
+// checked every time at runtime, because tests set this after program
+// startup.
+func inTest() bool {
+	inTest, _ := strconv.ParseBool(os.Getenv("IN_TS_TEST"))
+	return inTest
+}

wgengine/magicsock/debugknobs_ios.go

@@ -0,0 +1,20 @@
+// 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 magicsock
+
+// All knobs are disabled on iOS.
+// Further, they're const, so the toolchain can produce smaller binaries.
+const (
+	logPacketDests          = false
+	debugDisco              = false
+	debugOmitLocalAddresses = false
+	debugUseDerpRouteEnv    = ""
+	debugUseDerpRoute       = false
+	logDerpVerbose          = false
+	debugReSTUNStopOnIdle   = false
+	debugAlwaysDERP         = false
+)
+
+func inTest() bool { return false }

wgengine/magicsock/magicsock.go

@@ -59,35 +59,6 @@ import (
 	"tailscale.com/wgengine/wgcfg"
 )
 
-// Various debugging and experimental tweakables, set by environment
-// variable.
-var (
-	// logPacketDests prints the known addresses for a peer every time
-	// they change, in the legacy (non-discovery) endpoint code only.
-	logPacketDests, _ = strconv.ParseBool(os.Getenv("TS_DEBUG_LOG_PACKET_DESTS"))
-	// debugDisco prints verbose logs of active discovery events as
-	// they happen.
-	debugDisco, _ = strconv.ParseBool(os.Getenv("TS_DEBUG_DISCO"))
-	// debugOmitLocalAddresses removes all local interface addresses
-	// from magicsock's discovered local endpoints. Used in some tests.
-	debugOmitLocalAddresses, _ = strconv.ParseBool(os.Getenv("TS_DEBUG_OMIT_LOCAL_ADDRS"))
-	// debugUseDerpRoute temporarily (2020-03-22) controls whether DERP
-	// reverse routing is enabled (Issue 150). It will become always true
-	// later.
-	debugUseDerpRouteEnv = os.Getenv("TS_DEBUG_ENABLE_DERP_ROUTE")
-	debugUseDerpRoute, _ = strconv.ParseBool(debugUseDerpRouteEnv)
-	// logDerpVerbose logs all received DERP packets, including their
-	// full payload.
-	logDerpVerbose, _ = strconv.ParseBool(os.Getenv("TS_DEBUG_DERP"))
-	// debugReSTUNStopOnIdle unconditionally enables the "shut down
-	// STUN if magicsock is idle" behavior that normally only triggers
-	// on mobile devices, lowers the shutdown interval, and logs more
-	// verbosely about idle measurements.
-	debugReSTUNStopOnIdle, _ = strconv.ParseBool(os.Getenv("TS_DEBUG_RESTUN_STOP_ON_IDLE"))
-	// debugAlwaysDERP disables the use of UDP, forcing all peer communication over DERP.
-	debugAlwaysDERP, _ = strconv.ParseBool(os.Getenv("TS_DEBUG_ALWAYS_USE_DERP"))
-)
-
 // useDerpRoute reports whether magicsock should enable the DERP
 // return path optimization (Issue 150).
 func useDerpRoute() bool {
@@ -101,17 +72,6 @@ func useDerpRoute() bool {
 	return false
 }
 
-// inTest reports whether the running program is a test that set the
-// IN_TS_TEST environment variable.
-//
-// Unlike the other debug tweakables above, this one needs to be
-// checked every time at runtime, because tests set this after program
-// startup.
-func inTest() bool {
-	inTest, _ := strconv.ParseBool(os.Getenv("IN_TS_TEST"))
-	return inTest
-}
-
 // A Conn routes UDP packets and actively manages a list of its endpoints.
 // It implements wireguard/conn.Bind.
 type Conn struct {
@@ -893,11 +853,17 @@ func (c *Conn) populateCLIPingResponseLocked(res *ipnstate.PingResult, latency t
 	}
 	regionID := int(ep.Port())
 	res.DERPRegionID = regionID
-	if c.derpMap != nil {
-		if dr, ok := c.derpMap.Regions[regionID]; ok {
-			res.DERPRegionCode = dr.RegionCode
-		}
+	res.DERPRegionCode = c.derpRegionCodeLocked(regionID)
+}
+
+func (c *Conn) derpRegionCodeLocked(regionID int) string {
+	if c.derpMap == nil {
+		return ""
 	}
+	if dr, ok := c.derpMap.Regions[regionID]; ok {
+		return dr.RegionCode
+	}
+	return ""
 }
 
 // DiscoPublicKey returns the discovery public key.
@@ -2800,13 +2766,14 @@ func (c *Conn) ParseEndpoint(endpointStr string) (conn.Endpoint, error) {
 	}
 	pk := key.Public(endpoints.PublicKey)
 	discoKey := endpoints.DiscoKey
-	c.logf("magicsock: ParseEndpoint: key=%s: disco=%s ipps=%s", pk.ShortString(), discoKey.ShortString(), derpStr(endpoints.IPPorts.String()))
 
 	c.mu.Lock()
 	defer c.mu.Unlock()
 	if discoKey.IsZero() {
+		c.logf("magicsock: ParseEndpoint: key=%s: disco=%s legacy=%s", pk.ShortString(), discoKey.ShortString(), derpStr(endpoints.IPPorts.String()))
 		return c.createLegacyEndpointLocked(pk, endpoints.IPPorts, endpointStr)
 	}
+
 	de := &discoEndpoint{
 		c:             c,
 		publicKey:     tailcfg.NodeKey(pk),        // peer public key (for WireGuard + DERP)
@@ -2817,7 +2784,35 @@ func (c *Conn) ParseEndpoint(endpointStr string) (conn.Endpoint, error) {
 		endpointState: map[netaddr.IPPort]*endpointState{},
 	}
 	de.initFakeUDPAddr()
-	de.updateFromNode(c.nodeOfDisco[de.discoKey])
+	n := c.nodeOfDisco[de.discoKey]
+	de.updateFromNode(n)
+	c.logf("magicsock: ParseEndpoint: key=%s: disco=%s; %v", pk.ShortString(), discoKey.ShortString(), logger.ArgWriter(func(w *bufio.Writer) {
+		if n == nil {
+			w.WriteString("nil node")
+			return
+		}
+		const derpPrefix = "127.3.3.40:"
+		if strings.HasPrefix(n.DERP, derpPrefix) {
+			ipp, _ := netaddr.ParseIPPort(n.DERP)
+			regionID := int(ipp.Port())
+			code := c.derpRegionCodeLocked(regionID)
+			if code != "" {
+				code = "(" + code + ")"
+			}
+			fmt.Fprintf(w, "derp=%v%s ", regionID, code)
+		}
+
+		for _, a := range n.AllowedIPs {
+			if a.IsSingleIP() {
+				fmt.Fprintf(w, "aip=%v ", a.IP())
+			} else {
+				fmt.Fprintf(w, "aip=%v ", a)
+			}
+		}
+		for _, ep := range n.Endpoints {
+			fmt.Fprintf(w, "ep=%v ", ep)
+		}
+	}))
 	c.endpointOfDisco[de.discoKey] = de
 	return de, nil
 }

wgengine/netstack/netstack.go

@@ -468,19 +468,37 @@ func (ns *Impl) injectInbound(p *packet.Parsed, t *tstun.Wrapper) filter.Respons
 	return filter.DropSilently
 }
 
+func netaddrIPFromNetstackIP(s tcpip.Address) netaddr.IP {
+	switch len(s) {
+	case 4:
+		return netaddr.IPv4(s[0], s[1], s[2], s[3])
+	case 16:
+		var a [16]byte
+		copy(a[:], s)
+		return netaddr.IPFrom16(a)
+	}
+	return netaddr.IP{}
+}
+
 func (ns *Impl) acceptTCP(r *tcp.ForwarderRequest) {
 	reqDetails := r.ID()
 	if debugNetstack {
 		ns.logf("[v2] TCP ForwarderRequest: %s", stringifyTEI(reqDetails))
 	}
-	dialAddr := reqDetails.LocalAddress
-	dialNetAddr, _ := netaddr.FromStdIP(net.IP(dialAddr))
-	isTailscaleIP := tsaddr.IsTailscaleIP(dialNetAddr)
+	clientRemoteIP := netaddrIPFromNetstackIP(reqDetails.RemoteAddress)
+	if !clientRemoteIP.IsValid() {
+		ns.logf("invalid RemoteAddress in TCP ForwarderRequest: %s", stringifyTEI(reqDetails))
+		r.Complete(true)
+		return
+	}
+
+	dialIP := netaddrIPFromNetstackIP(reqDetails.LocalAddress)
+	isTailscaleIP := tsaddr.IsTailscaleIP(dialIP)
 	defer func() {
 		if !isTailscaleIP {
 			// if this is a subnet IP, we added this in before the TCP handshake
 			// so netstack is happy TCP-handshaking as a subnet IP
-			ns.removeSubnetAddress(dialNetAddr)
+			ns.removeSubnetAddress(dialIP)
 		}
 	}()
 	var wq waiter.Queue
@@ -490,21 +508,31 @@ func (ns *Impl) acceptTCP(r *tcp.ForwarderRequest) {
 		return
 	}
 	r.Complete(false)
+
+	// Asynchronously start the TCP handshake. Note that the
+	// gonet.TCPConn methods c.RemoteAddr() and c.LocalAddr() will
+	// return nil until the handshake actually completes. But we
+	// have the remote address in reqDetails instead, so we don't
+	// use RemoteAddr. The byte copies in both directions in
+	// forwardTCP will block until the TCP handshake is complete.
 	c := gonet.NewTCPConn(&wq, ep)
+
 	if ns.ForwardTCPIn != nil {
 		ns.ForwardTCPIn(c, reqDetails.LocalPort)
 		return
 	}
 	if isTailscaleIP {
-		dialAddr = tcpip.Address(net.ParseIP("127.0.0.1")).To4()
+		dialIP = netaddr.IPv4(127, 0, 0, 1)
 	}
-	ns.forwardTCP(c, &wq, dialAddr, reqDetails.LocalPort)
+	dialAddr := netaddr.IPPortFrom(dialIP, uint16(reqDetails.LocalPort))
+	ns.forwardTCP(c, clientRemoteIP, &wq, dialAddr)
 }
 
-func (ns *Impl) forwardTCP(client *gonet.TCPConn, wq *waiter.Queue, dialAddr tcpip.Address, dialPort uint16) {
+func (ns *Impl) forwardTCP(client *gonet.TCPConn, clientRemoteIP netaddr.IP, wq *waiter.Queue, dialAddr netaddr.IPPort) {
 	defer client.Close()
-	dialAddrStr := net.JoinHostPort(dialAddr.String(), strconv.Itoa(int(dialPort)))
+	dialAddrStr := dialAddr.String()
 	ns.logf("[v2] netstack: forwarding incoming connection to %s", dialAddrStr)
+
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 	waitEntry, notifyCh := waiter.NewChannelEntry(nil)
@@ -530,7 +558,6 @@ func (ns *Impl) forwardTCP(client *gonet.TCPConn, wq *waiter.Queue, dialAddr tcp
 	defer server.Close()
 	backendLocalAddr := server.LocalAddr().(*net.TCPAddr)
 	backendLocalIPPort, _ := netaddr.FromStdAddr(backendLocalAddr.IP, backendLocalAddr.Port, backendLocalAddr.Zone)
-	clientRemoteIP, _ := netaddr.FromStdIP(client.RemoteAddr().(*net.TCPAddr).IP)
 	ns.e.RegisterIPPortIdentity(backendLocalIPPort, clientRemoteIP)
 	defer ns.e.UnregisterIPPortIdentity(backendLocalIPPort)
 	connClosed := make(chan error, 2)

wgengine/router/router_linux.go

@@ -155,7 +155,11 @@ func newUserspaceRouter(logf logger.Logf, tunDev tun.Device, linkMon *monitor.Mo
 		}
 	}
 
-	return newUserspaceRouterAdvanced(logf, tunname, linkMon, ipt4, ipt6, osCommandRunner{}, supportsV6, supportsV6NAT)
+	cmd := osCommandRunner{
+		ambientCapNetAdmin: distro.Get() == distro.Synology,
+	}
+
+	return newUserspaceRouterAdvanced(logf, tunname, linkMon, ipt4, ipt6, cmd, supportsV6, supportsV6NAT)
 }
 
 func newUserspaceRouterAdvanced(logf logger.Logf, tunname string, linkMon *monitor.Mon, netfilter4, netfilter6 netfilterRunner, cmd commandRunner, supportsV6, supportsV6NAT bool) (Router, error) {

wgengine/router/runner.go

@@ -13,6 +13,9 @@ import (
 	"os/exec"
 	"strconv"
 	"strings"
+	"syscall"
+
+	"golang.org/x/sys/unix"
 )
 
 // commandRunner abstracts helpers to run OS commands. It exists
@@ -23,7 +26,16 @@ type commandRunner interface {
 	output(...string) ([]byte, error)
 }
 
-type osCommandRunner struct{}
+type osCommandRunner struct {
+	// ambientCapNetAdmin determines whether commands are executed with
+	// CAP_NET_ADMIN.
+	// CAP_NET_ADMIN is required when running as non-root and executing cmds
+	// like `ip rule`. Even if our process has the capability, we need to
+	// explicitly grant it to the new process.
+	// We specifically need this for Synology DSM7 where tailscaled no longer
+	// runs as root.
+	ambientCapNetAdmin bool
+}
 
 // errCode extracts and returns the process exit code from err, or
 // zero if err is nil.
@@ -55,7 +67,13 @@ func (o osCommandRunner) output(args ...string) ([]byte, error) {
 		return nil, errors.New("cmd: no argv[0]")
 	}
 
-	out, err := exec.Command(args[0], args[1:]...).CombinedOutput()
+	cmd := exec.Command(args[0], args[1:]...)
+	if o.ambientCapNetAdmin {
+		cmd.SysProcAttr = &syscall.SysProcAttr{
+			AmbientCaps: []uintptr{unix.CAP_NET_ADMIN},
+		}
+	}
+	out, err := cmd.CombinedOutput()
 	if err != nil {
 		return nil, fmt.Errorf("running %q failed: %w\n%s", strings.Join(args, " "), err, out)
 	}

wgengine/userspace.go

@@ -84,6 +84,7 @@ type userspaceEngine struct {
 	wgLogger          *wglog.Logger //a wireguard-go logging wrapper
 	reqCh             chan struct{}
 	waitCh            chan struct{} // chan is closed when first Close call completes; contrast with closing bool
+	magicConnStarted  chan struct{} // chan is closed after magicConn.Start
 	timeNow           func() mono.Time
 	tundev            *tstun.Wrapper
 	wgdev             *device.Device
@@ -108,6 +109,7 @@ type userspaceEngine struct {
 
 	wgLock              sync.Mutex // serializes all wgdev operations; see lock order comment below
 	lastCfgFull         wgcfg.Config
+	lastNMinPeers       int
 	lastRouterSig       deephash.Sum // of router.Config
 	lastEngineSigFull   deephash.Sum // of full wireguard config
 	lastEngineSigTrim   deephash.Sum // of trimmed wireguard config
@@ -248,13 +250,14 @@ func NewUserspaceEngine(logf logger.Logf, conf Config) (_ Engine, reterr error)
 	closePool.add(tsTUNDev)
 
 	e := &userspaceEngine{
-		timeNow:        mono.Now,
-		logf:           logf,
-		reqCh:          make(chan struct{}, 1),
-		waitCh:         make(chan struct{}),
-		tundev:         tsTUNDev,
-		router:         conf.Router,
-		confListenPort: conf.ListenPort,
+		timeNow:          mono.Now,
+		logf:             logf,
+		reqCh:            make(chan struct{}, 1),
+		waitCh:           make(chan struct{}),
+		tundev:           tsTUNDev,
+		router:           conf.Router,
+		confListenPort:   conf.ListenPort,
+		magicConnStarted: make(chan struct{}),
 	}
 	e.isLocalAddr.Store(tsaddr.NewContainsIPFunc(nil))
 	e.isDNSIPOverTailscale.Store(tsaddr.NewContainsIPFunc(nil))
@@ -370,7 +373,7 @@ func NewUserspaceEngine(logf logger.Logf, conf Config) (_ Engine, reterr error)
 
 	// It's a little pointless to apply no-op settings here (they
 	// should already be empty?), but it at least exercises the
-	// router implementation early on the machine.
+	// router implementation early on.
 	e.logf("Clearing router settings...")
 	if err := e.router.Set(nil); err != nil {
 		return nil, err
@@ -379,6 +382,7 @@ func NewUserspaceEngine(logf logger.Logf, conf Config) (_ Engine, reterr error)
 	e.linkMon.Start()
 	e.logf("Starting magicsock...")
 	e.magicConn.Start()
+	close(e.magicConnStarted)
 
 	go e.pollResolver()
 
@@ -606,7 +610,7 @@ func (e *userspaceEngine) maybeReconfigWireguardLocked(discoChanged map[key.Publ
 	// based on the full config. Prune off all the peers
 	// and only add the active ones back.
 	min := full
-	min.Peers = nil
+	min.Peers = make([]wgcfg.Peer, 0, e.lastNMinPeers)
 
 	// We'll only keep a peer around if it's been active in
 	// the past 5 minutes. That's more than WireGuard's key
@@ -650,6 +654,7 @@ func (e *userspaceEngine) maybeReconfigWireguardLocked(discoChanged map[key.Publ
 			trimmedDisco[dk] = true
 		}
 	}
+	e.lastNMinPeers = len(min.Peers)
 
 	if !deephash.Update(&e.lastEngineSigTrim, &min, trimmedDisco, trackDisco, trackIPs) {
 		// No changes
@@ -921,8 +926,8 @@ func (e *userspaceEngine) getStatus() (*Status, error) {
 		errc <- err
 	}()
 
-	pp := make(map[wgkey.Key]*ipnstate.PeerStatusLite)
-	p := &ipnstate.PeerStatusLite{}
+	pp := make(map[wgkey.Key]ipnstate.PeerStatusLite)
+	var p ipnstate.PeerStatusLite
 
 	var hst1, hst2, n int64
 
@@ -954,11 +959,10 @@ func (e *userspaceEngine) getStatus() (*Status, error) {
 			if err != nil {
 				return nil, fmt.Errorf("IpcGetOperation: invalid key in line %q", line)
 			}
-			p = &ipnstate.PeerStatusLite{}
-			pp[wgkey.Key(pk)] = p
-
-			key := tailcfg.NodeKey(pk)
-			p.NodeKey = key
+			if !p.NodeKey.IsZero() {
+				pp[wgkey.Key(p.NodeKey)] = p
+			}
+			p = ipnstate.PeerStatusLite{NodeKey: tailcfg.NodeKey(pk)}
 		case "rx_bytes":
 			n, err = mem.ParseInt(v, 10, 64)
 			p.RxBytes = n
@@ -986,6 +990,9 @@ func (e *userspaceEngine) getStatus() (*Status, error) {
 			} // else leave at time.IsZero()
 		}
 	}
+	if !p.NodeKey.IsZero() {
+		pp[wgkey.Key(p.NodeKey)] = p
+	}
 	if err := <-errc; err != nil {
 		return nil, fmt.Errorf("IpcGetOperation: %v", err)
 	}
@@ -993,10 +1000,19 @@ func (e *userspaceEngine) getStatus() (*Status, error) {
 	e.mu.Lock()
 	defer e.mu.Unlock()
 
-	var peers []ipnstate.PeerStatusLite
+	// Do two passes, one to calculate size and the other to populate.
+	// This code is sensitive to allocations.
+	npeers := 0
+	for _, pk := range e.peerSequence {
+		if _, ok := pp[pk]; ok { // ignore idle ones not in wireguard-go's config
+			npeers++
+		}
+	}
+
+	peers := make([]ipnstate.PeerStatusLite, 0, npeers)
 	for _, pk := range e.peerSequence {
 		if p, ok := pp[pk]; ok { // ignore idle ones not in wireguard-go's config
-			peers = append(peers, *p)
+			peers = append(peers, p)
 		}
 	}
 
@@ -1079,6 +1095,10 @@ func (e *userspaceEngine) LinkChange(_ bool) {
 }
 
 func (e *userspaceEngine) linkChange(changed bool, cur *interfaces.State) {
+	// Issue 2733: wait for e.magicConn to be started; there's two tiny
+	// windows at startup where this callback can be run before Start
+	<-e.magicConnStarted
+
 	up := cur.AnyInterfaceUp()
 	if !up {
 		e.logf("LinkChange: all links down; pausing: %v", cur)

words/scales.txt

@@ -0,0 +1,158 @@
+lizard
+crocodile
+snake
+dragon
+catfish
+bass
+salmon
+tuna
+hammerhead
+eel
+carp
+trout
+mahi
+snapper
+bluegill
+sole
+cod
+triceratops
+edmontosaurus
+saurolophus
+liberty
+justice
+pangolin
+turtle
+tortoise
+alligator
+butterfly
+iguana
+pineapplefish
+anaconda
+puffin
+cardassian
+cloud
+nominal
+ordinal
+interval
+ratio
+vernier
+lime
+scala
+boa
+cobra
+richter
+kelvin
+celsius
+decibel
+beaufort
+mohs
+pauling
+python
+mamba
+alkaline
+climb
+moth
+eagle
+woodpecker
+morpho
+tautara
+anoles
+theopods
+owl
+frog
+lionfish
+morray
+clownfish
+ostrich
+stork
+egret
+map
+grue
+tiyanki
+broadnose
+basking
+goblin
+porbeagle
+chuckwalla
+tawny
+bramble
+kitefin
+agamas
+komodo
+bull
+monitor
+chameleon
+tegus
+gecko
+micro
+gray
+allosaurus
+glyptodon
+basilisk
+cordylus
+tegu
+sailfin
+mountain
+dinosaur
+goanna
+herring
+minnow
+perch
+coho
+lake
+arctic
+pumpkinseed
+salamander
+mudpuppy
+gopher
+chickadee
+toad
+shark
+roach
+tyrannosaurus
+velociraptor
+
+# Musical scales
+acoustic
+alpha
+altered
+augmented
+bebop
+beta
+blues
+bushi
+byzantine
+chromatic
+delta
+diatonic
+diminished
+dominant
+dorian
+enigmatic
+freygish
+gamma
+harmonic
+heptatonic
+hexatonic
+hirajoshi
+in
+insen
+istrian
+iwato
+jazz
+locrian
+major
+minor
+mixolydian
+musical
+octatonic
+pentatonic
+phrygian
+pierce
+prometheus
+pythagorean
+symmetric
+tet
+tone
+tritone
+yo

words/tails.txt

@@ -0,0 +1,211 @@
+orca
+shark
+capybara
+fox
+turtle
+fish
+dolphin
+armadillo
+hedgehog
+dhole
+dog
+cat
+jaguar
+cheetah
+leopard
+cougar
+lion
+tapir
+anteater
+monkey
+snake
+scorpion
+jerboa
+opossum
+stingray
+colobus
+euplectes
+jay
+finch
+hawk
+beaver
+mouse
+moose
+alligator
+salamander
+tadpole
+astrapia
+pug
+greyhound
+foxhound
+bushbaby
+aardvark
+aardwolf
+pangolin
+porcupine
+genet
+springhare
+kangaroo
+koala
+ostrich
+dingo
+platypus
+camel
+horse
+echidna
+wombat
+crocodile
+whale
+narwhal
+humpback
+marmoset
+tucuxi
+beluga
+porpoise
+sparrow
+pigeon
+owl
+hummingbird
+robin
+starling
+manakin
+warbler
+penguin
+snowfinch
+broadbill
+thrush
+bishop
+swallow
+bittern
+caracara
+manx
+possum
+lemur
+deer
+peacock
+ratfish
+vulture
+rat
+takaya
+skunk
+tuxedo
+turkey
+elephant
+civet
+ainu
+husky
+akita
+alpaca
+spaniel
+terrier
+hare
+auroch
+axolotl
+bandicoot
+beagle
+beago
+collie
+tiger
+liger
+rhino
+bobcat
+corgi
+dachshund
+giraffe
+bonobo
+cetacean
+bear
+hyena
+burmese
+caracal
+goat
+chameleon
+chihuahua
+chimp
+cow
+cuscus
+pinscher
+dunker
+mau
+ermine
+feist
+spitz
+squirrel
+gerbil
+hampster
+panda
+gibbon
+flyingfox
+jackal
+macaque
+kinkajou
+lynx
+manatee
+mole
+ocelot
+otter
+panther
+pig
+prairiedog
+puma
+hippo
+quokka
+quoll
+bunny
+raccoon
+tamarin
+reindeer
+hyrax
+saiga
+sable
+serval
+spanador
+springbok
+tuatara
+dropbear
+vaquita
+wallaby
+walrus
+weasel
+wolf
+zebra
+zonkey
+donkey
+mule
+zebu
+cuttlefish
+unicorn
+meerkat
+jackalope
+heron
+fawn
+warthog
+drake
+badger
+zapus
+yak
+werewolf
+tahr
+fossa
+xerus
+centaur
+raptor
+long
+sheep
+quetzal
+wildebeest
+motmot
+coati
+drongo
+boston
+myth
+saga
+fable
+folk
+fairy
+hound
+risk
+coin
+tyrannosaurus
+velociraptor
+siren

words/words.go

@@ -0,0 +1,59 @@
+// 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 words contains accessors for some nice words.
+package words
+
+import (
+	"bytes"
+	_ "embed"
+	"strings"
+	"sync"
+)
+
+//go:embed tails.txt
+var tailsTxt []byte
+
+//go:embed scales.txt
+var scalesTxt []byte
+
+var (
+	once          sync.Once
+	tails, scales []string
+)
+
+// Tails returns words about tails.
+func Tails() []string {
+	once.Do(initWords)
+	return tails
+}
+
+// Scales returns words about scales.
+func Scales() []string {
+	once.Do(initWords)
+	return scales
+}
+
+func initWords() {
+	tails = parseWords(tailsTxt)
+	scales = parseWords(scalesTxt)
+}
+
+func parseWords(txt []byte) []string {
+	n := bytes.Count(txt, []byte{'\n'})
+	ret := make([]string, 0, n)
+	for len(txt) > 0 {
+		word := txt
+		i := bytes.IndexByte(txt, '\n')
+		if i != -1 {
+			word, txt = word[:i], txt[i+1:]
+		} else {
+			txt = nil
+		}
+		if word := strings.TrimSpace(string(word)); word != "" && word[0] != '#' {
+			ret = append(ret, word)
+		}
+	}
+	return ret
+}

words/words_test.go

@@ -0,0 +1,39 @@
+// 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 words
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestWords(t *testing.T) {
+	test := func(t *testing.T, words []string) {
+		t.Helper()
+		if len(words) == 0 {
+			t.Error("no words")
+		}
+		seen := map[string]bool{}
+		for _, w := range words {
+			if seen[w] {
+				t.Errorf("dup word %q", w)
+			}
+			seen[w] = true
+			if w == "" || strings.IndexFunc(w, nonASCIILower) != -1 {
+				t.Errorf("malformed word %q", w)
+			}
+		}
+	}
+	t.Run("tails", func(t *testing.T) { test(t, Tails()) })
+	t.Run("scales", func(t *testing.T) { test(t, Scales()) })
+	t.Logf("%v tails * %v scales = %v beautiful combinations", len(Tails()), len(Scales()), len(Tails())*len(Scales()))
+}
+
+func nonASCIILower(r rune) bool {
+	if 'a' <= r && r <= 'z' {
+		return false
+	}
+	return true
+}