cmd/tailscale: add "version" subcommand

Fixes #448

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

cmd/tailscale/cli/cli.go

@@ -31,7 +31,8 @@ func ActLikeCLI() bool {
 		return false
 	}
 	switch os.Args[1] {
-	case "up", "status", "netcheck", "-h", "--help":
+	case "up", "status", "netcheck", "version",
+		"-V", "--version", "-h", "--help":
 		return true
 	}
 	return false
@@ -39,6 +40,10 @@ func ActLikeCLI() bool {
 
 // Run runs the CLI. The args do not include the binary name.
 func Run(args []string) error {
+	if len(args) == 1 && (args[0] == "-V" || args[0] == "--version") {
+		args = []string{"version"}
+	}
+
 	rootfs := flag.NewFlagSet("tailscale", flag.ExitOnError)
 	rootfs.StringVar(&rootArgs.socket, "socket", paths.DefaultTailscaledSocket(), "path to tailscaled's unix socket")
 
@@ -54,6 +59,7 @@ func Run(args []string) error {
 			upCmd,
 			netcheckCmd,
 			statusCmd,
+			versionCmd,
 		},
 		FlagSet: rootfs,
 		Exec:    func(context.Context, []string) error { return flag.ErrHelp },

cmd/tailscale/cli/version.go

@@ -0,0 +1,69 @@
+// 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 cli
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"log"
+
+	"github.com/peterbourgon/ff/v2/ffcli"
+	"tailscale.com/ipn"
+	"tailscale.com/version"
+)
+
+var versionCmd = &ffcli.Command{
+	Name:       "version",
+	ShortUsage: "version [flags]",
+	ShortHelp:  "Print Tailscale version",
+	FlagSet: (func() *flag.FlagSet {
+		fs := flag.NewFlagSet("version", flag.ExitOnError)
+		fs.BoolVar(&versionArgs.daemon, "daemon", true, "also print local node's daemon version")
+		return fs
+	})(),
+	Exec: runVersion,
+}
+
+var versionArgs struct {
+	daemon bool // also check local node's daemon version
+}
+
+func runVersion(ctx context.Context, args []string) error {
+	if len(args) > 0 {
+		log.Fatalf("too many non-flag arguments: %q", args)
+	}
+	if !versionArgs.daemon {
+		fmt.Println(version.LONG)
+		return nil
+	}
+	fmt.Printf("Client: %s\n", version.LONG)
+
+	c, bc, ctx, cancel := connect(ctx)
+	defer cancel()
+
+	bc.AllowVersionSkew = true
+
+	done := make(chan struct{})
+
+	bc.SetNotifyCallback(func(n ipn.Notify) {
+		if n.ErrMessage != nil {
+			log.Fatal(*n.ErrMessage)
+		}
+		if n.Status != nil {
+			fmt.Printf("Daemon: %s\n", n.Version)
+			close(done)
+		}
+	})
+	go pump(ctx, bc, c)
+
+	bc.RequestStatus()
+	select {
+	case <-done:
+		return nil
+	case <-ctx.Done():
+		return ctx.Err()
+	}
+}