safesocket: simplify API.

On unix, we want to provide a full path to the desired unix socket.

On windows, currently we want to provide a TCP port, but someday
we'll also provide a "path-ish" object for a named pipe.

For now, simplify the API down to exactly a path and a TCP port.

Signed-off-by: David Anderson <dave@natulte.net>

cmd/tailscale/tailscale.go

@@ -52,6 +52,7 @@ func main() {
 		log.Printf("fixConsoleOutput: %v\n", err)
 	}
 
+	socket := getopt.StringLong("socket", 0, "/run/tailscale/tailscaled.sock", "path of tailscaled's unix socket")
 	server := getopt.StringLong("server", 's', "https://login.tailscale.com", "URL to tailcontrol server")
 	nuroutes := getopt.BoolLong("no-single-routes", 'N', "disallow (non-subnet) routes to single nodes")
 	routeall := getopt.BoolLong("remote-routes", 'R', "accept routes advertised by remote nodes")
@@ -84,7 +85,7 @@ func main() {
 		AdvertiseRoutes:  adv,
 	}
 
-	c, err := safesocket.Connect("", "Tailscale", "tailscaled", 41112)
+	c, err := safesocket.Connect(*socket, 0)
 	if err != nil {
 		log.Fatalf("safesocket.Connect: %v\n", err)
 	}

cmd/tailscaled/tailscaled.go

@@ -38,6 +38,7 @@ func main() {
 	tunname := getopt.StringLong("tun", 0, "ts0", "tunnel interface name")
 	listenport := getopt.Uint16Long("port", 'p', magicsock.DefaultPort, "WireGuard port (0=autoselect)")
 	statepath := getopt.StringLong("state", 0, "", "Path of state file")
+	socketpath := getopt.StringLong("socket", 's', "/run/tailscale/tailscaled.sock", "Path of the service unix socket")
 
 	logf := wgengine.RusagePrefixLog(log.Printf)
 
@@ -56,6 +57,10 @@ func main() {
 		log.Fatalf("--state is required")
 	}
 
+	if *socketpath == "" {
+		log.Fatalf("--socket is required")
+	}
+
 	if *debug != "" {
 		go runDebugServer(*debug)
 	}
@@ -72,6 +77,7 @@ func main() {
 	e = wgengine.NewWatchdog(e)
 
 	opts := ipnserver.Options{
+		SocketPath:         *socketpath,
 		StatePath:          *statepath,
 		AutostartStateKey:  globalStateKey,
 		SurviveDisconnects: true,

ipn/ipnserver/server.go

@@ -39,6 +39,12 @@
 
 // Options is the configuration of the Tailscale node agent.
 type Options struct {
+	// SocketPath, on unix systems, is the unix socket path to listen
+	// on for frontend connections.
+	SocketPath string
+	// Port, on windows, is the localhost TCP port to listen on for
+	// frontend connections.
+	Port int
 	// StatePath is the path to the stored agent state.
 	StatePath string
 	// AutostartStateKey, if non-empty, immediately starts the agent
@@ -72,7 +78,7 @@ func pump(logf logger.Logf, ctx context.Context, bs *ipn.BackendServer, s net.Co
 func Run(rctx context.Context, logf logger.Logf, logid string, opts Options, e wgengine.Engine) error {
 	bo := backoff.Backoff{Name: "ipnserver"}
 
-	listen, _, err := safesocket.Listen("", "Tailscale", "tailscaled", 41112)
+	listen, _, err := safesocket.Listen(opts.SocketPath, uint16(opts.Port))
 	if err != nil {
 		return fmt.Errorf("safesocket.Listen: %v", err)
 	}

safesocket/basic_test.go

@@ -10,7 +10,7 @@
 )
 
 func TestBasics(t *testing.T) {
-	l, port, err := Listen("COOKIE", "Tailscale", "test", 0)
+	l, port, err := Listen("test", 0)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -42,7 +42,7 @@ func TestBasics(t *testing.T) {
 	}()
 
 	go func() {
-		c, err := Connect("COOKIE", "Tailscale", "test", port)
+		c, err := Connect("test", port)
 		if err != nil {
 			errs <- err
 			return

safesocket/pipe_windows.go

@@ -24,9 +24,8 @@ func ConnCloseWrite(c net.Conn) error {
 }
 
 // TODO(apenwarr): handle magic cookie auth
-func Connect(cookie, vendor, name string, port uint16) (net.Conn, error) {
-	p := path(vendor, name, port)
-	pipe, err := net.Dial("tcp", p)
+func Connect(path string, port uint16) (net.Conn, error) {
+	pipe, err := net.Dial("tcp", fmt.Sprintf("127.0.0.1:%d", port))
 	if err != nil {
 		return nil, err
 	}
@@ -46,12 +45,11 @@ func setFlags(network, address string, c syscall.RawConn) error {
 //   just always using a TCP session on a fixed port on localhost. As a
 //   result, on Windows we ignore the vendor and name strings.
 // TODO(apenwarr): handle magic cookie auth
-func Listen(cookie, vendor, name string, port uint16) (net.Listener, uint16, error) {
+func Listen(path string, port uint16) (net.Listener, uint16, error) {
 	lc := net.ListenConfig{
 		Control: setFlags,
 	}
-	p := path(vendor, name, port)
-	pipe, err := lc.Listen(context.Background(), "tcp", p)
+	pipe, err := lc.Listen(context.Background(), "tcp", fmt.Sprintf("127.0.0.1:%d", port))
 	if err != nil {
 		return nil, 0, err
 	}

safesocket/unixsocket.go

@@ -12,10 +12,6 @@
 	"os"
 )
 
-func path(vendor, name string) string {
-	return fmt.Sprintf("%s-%s.sock", vendor, name)
-}
-
 func ConnCloseRead(c net.Conn) error {
 	return c.(*net.UnixConn).CloseRead()
 }
@@ -25,8 +21,8 @@ func ConnCloseWrite(c net.Conn) error {
 }
 
 // TODO(apenwarr): handle magic cookie auth
-func Connect(cookie, vendor, name string, port uint16) (net.Conn, error) {
-	pipe, err := net.Dial("unix", path(vendor, name))
+func Connect(path string, port uint16) (net.Conn, error) {
+	pipe, err := net.Dial("unix", path)
 	if err != nil {
 		return nil, err
 	}
@@ -34,7 +30,7 @@ func Connect(cookie, vendor, name string, port uint16) (net.Conn, error) {
 }
 
 // TODO(apenwarr): handle magic cookie auth
-func Listen(cookie, vendor, name string, port uint16) (net.Listener, uint16, error) {
+func Listen(path string, port uint16) (net.Listener, uint16, error) {
 	// Unix sockets hang around in the filesystem even after nobody
 	// is listening on them. (Which is really unfortunate but long-
 	// entrenched semantics.) Try connecting first; if it works, then
@@ -45,17 +41,16 @@ func Listen(cookie, vendor, name string, port uint16) (net.Listener, uint16, err
 	// "proper" daemon usually uses a dance involving pidfiles to first
 	// ensure that no other instances of itself are running, but that's
 	// beyond the scope of our simple socket library.
-	p := path(vendor, name)
-	c, err := net.Dial("unix", p)
+	c, err := net.Dial("unix", path)
 	if err == nil {
 		c.Close()
-		return nil, 0, fmt.Errorf("%v: address already in use", p)
+		return nil, 0, fmt.Errorf("%v: address already in use", path)
 	}
-	_ = os.Remove(p)
-	pipe, err := net.Listen("unix", p)
+	_ = os.Remove(path)
+	pipe, err := net.Listen("unix", path)
 	if err != nil {
 		return nil, 0, err
 	}
-	os.Chmod(p, 0666)
+	os.Chmod(path, 0666)
 	return pipe, 0, err
 }