cmd/tailscale/cli: add basic 'down' subcommand

RELNOTE=yes

cmd/tailscale/cli/cli.go

@@ -31,7 +31,7 @@ func ActLikeCLI() bool {
 		return false
 	}
 	switch os.Args[1] {
-	case "up", "status", "netcheck", "ping", "version",
+	case "up", "down", "status", "netcheck", "ping", "version",
 		"debug",
 		"-V", "--version", "-h", "--help":
 		return true
@@ -58,6 +58,7 @@ func Run(args []string) error {
 `),
 		Subcommands: []*ffcli.Command{
 			upCmd,
+			downCmd,
 			netcheckCmd,
 			statusCmd,
 			pingCmd,

cmd/tailscale/cli/down.go

@@ -0,0 +1,67 @@
+// 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"
+	"log"
+	"time"
+
+	"github.com/peterbourgon/ff/v2/ffcli"
+	"tailscale.com/ipn"
+)
+
+var downCmd = &ffcli.Command{
+	Name:       "down",
+	ShortUsage: "down",
+	ShortHelp:  "Disconnect from Tailscale",
+
+	Exec: runDown,
+}
+
+func runDown(ctx context.Context, args []string) error {
+	if len(args) > 0 {
+		log.Fatalf("too many non-flag arguments: %q", args)
+	}
+
+	c, bc, ctx, cancel := connect(ctx)
+	defer cancel()
+
+	timer := time.AfterFunc(5*time.Second, func() {
+		log.Fatalf("timeout running stop")
+	})
+	defer timer.Stop()
+
+	bc.SetNotifyCallback(func(n ipn.Notify) {
+		if n.ErrMessage != nil {
+			log.Fatal(*n.ErrMessage)
+		}
+		if n.Status != nil {
+			cur := n.Status.BackendState
+			switch cur {
+			case "Stopped":
+				log.Printf("already stopped")
+				cancel()
+			default:
+				log.Printf("was in state %q", cur)
+			}
+			return
+		}
+		if n.State != nil {
+			log.Printf("now in state %q", *n.State)
+			if *n.State == ipn.Stopped {
+				cancel()
+			}
+			return
+		}
+		log.Printf("Notify: %#v", n)
+	})
+
+	bc.RequestStatus()
+	bc.SetWantRunning(false)
+	pump(ctx, bc, c)
+
+	return nil
+}

ipn/backend.go

@@ -144,6 +144,9 @@ type Backend interface {
 	// WantRunning. This may cause the wireguard engine to
 	// reconfigure or stop.
 	SetPrefs(*Prefs)
+	// SetWantRunning is like SetPrefs but sets only the
+	// WantRunning field.
+	SetWantRunning(wantRunning bool)
 	// RequestEngineStatus polls for an update from the wireguard
 	// engine. Only needed if you want to display byte
 	// counts. Connection events are emitted automatically without

ipn/fake_test.go

@@ -79,6 +79,10 @@ func (b *FakeBackend) SetPrefs(new *Prefs) {
 	}
 }
 
+func (b *FakeBackend) SetWantRunning(v bool) {
+	b.SetPrefs(&Prefs{WantRunning: v})
+}
+
 func (b *FakeBackend) RequestEngineStatus() {
 	b.notify(Notify{Engine: &EngineStatus{}})
 }

ipn/ipnstate/ipnstate.go

@@ -90,6 +90,12 @@ type StatusBuilder struct {
 	st     Status
 }
 
+func (sb *StatusBuilder) SetBackendState(v string) {
+	sb.mu.Lock()
+	defer sb.mu.Unlock()
+	sb.st.BackendState = v
+}
+
 func (sb *StatusBuilder) Status() *Status {
 	sb.mu.Lock()
 	defer sb.mu.Unlock()

ipn/local.go

@@ -144,6 +144,8 @@ func (b *LocalBackend) UpdateStatus(sb *ipnstate.StatusBuilder) {
 	b.mu.Lock()
 	defer b.mu.Unlock()
 
+	sb.SetBackendState(b.state.String())
+
 	// TODO: hostinfo, and its networkinfo
 	// TODO: EngineStatus copy (and deprecate it?)
 	if b.netMap != nil {
@@ -796,6 +798,18 @@ func (b *LocalBackend) shieldsAreUp() bool {
 	return b.prefs.ShieldsUp
 }
 
+func (b *LocalBackend) SetWantRunning(wantRunning bool) {
+	b.mu.Lock()
+	new := b.prefs.Clone()
+	b.mu.Unlock()
+	if new.WantRunning == wantRunning {
+		return
+	}
+	new.WantRunning = wantRunning
+	b.logf("SetWantRunning: %v", wantRunning)
+	b.SetPrefs(new)
+}
+
 // SetPrefs saves new user preferences and propagates them throughout
 // the system. Implements Backend.
 func (b *LocalBackend) SetPrefs(new *Prefs) {

ipn/message.go

@@ -57,6 +57,7 @@ type Command struct {
 	Login                 *oauth2.Token
 	Logout                *NoArgs
 	SetPrefs              *SetPrefsArgs
+	SetWantRunning        *bool
 	RequestEngineStatus   *NoArgs
 	RequestStatus         *NoArgs
 	FakeExpireAfter       *FakeExpireAfterArgs
@@ -144,6 +145,9 @@ func (bs *BackendServer) GotCommand(cmd *Command) error {
 	} else if c := cmd.SetPrefs; c != nil {
 		bs.b.SetPrefs(c.New)
 		return nil
+	} else if c := cmd.SetWantRunning; c != nil {
+		bs.b.SetWantRunning(*c)
+		return nil
 	} else if c := cmd.RequestEngineStatus; c != nil {
 		bs.b.RequestEngineStatus()
 		return nil
@@ -266,6 +270,10 @@ func (bc *BackendClient) Ping(ip string) {
 	bc.send(Command{Ping: &PingArgs{IP: ip}})
 }
 
+func (bc *BackendClient) SetWantRunning(v bool) {
+	bc.send(Command{SetWantRunning: &v})
+}
+
 // MaxMessageSize is the maximum message size, in bytes.
 const MaxMessageSize = 10 << 20