ipn/ipnlocal: simplify authURL vs authURLSticky, remove interact field

The previous LocalBackend & CLI 'up' changes improved some stuff, but
might've been too aggressive in some edge cases.

This simplifies the authURL vs authURLSticky distinction and removes
the interact field, which seemed to just just be about duplicate URL
suppression in IPN bus, back from when the IPN bus was a single client
at a time. This moves that suppression to a different spot.

Fixes #12119
Updates #12028
Updates #12042

Change-Id: I1f8800b1e82ccc1c8a0d7abba559e7404ddf41e4
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

ipn/ipnlocal/local.go

@@ -259,10 +259,8 @@ type LocalBackend struct {
 	endpoints        []tailcfg.Endpoint
 	blocked          bool
 	keyExpired       bool
-	authURL          string    // cleared on Notify
+	authURL          string    // non-empty if not Running
-	authURLSticky    string    // not cleared on Notify
 	authURLTime      time.Time // when the authURL was received from the control server
-	interact         bool
 	egg              bool
 	prevIfState      *netmon.State
 	peerAPIServer    *peerAPIServer // or nil
@@ -785,7 +783,7 @@ func (b *LocalBackend) UpdateStatus(sb *ipnstate.StatusBuilder) {
 		s.Version = version.Long()
 		s.TUN = !b.sys.IsNetstack()
 		s.BackendState = b.state.String()
-		s.AuthURL = b.authURLSticky
+		s.AuthURL = b.authURL
 		if prefs := b.pm.CurrentPrefs(); prefs.Valid() && prefs.AutoUpdate().Check {
 			s.ClientVersion = b.lastClientVersion
 		}
@@ -1139,7 +1137,6 @@ func (b *LocalBackend) SetControlClientStatus(c controlclient.Client, st control
 	prefsChanged := false
 	prefs := b.pm.CurrentPrefs().AsStruct()
 	netMap := b.netMap
-	interact := b.interact
 
 	if prefs.ControlURL == "" {
 		// Once we get a message from the control plane, set
@@ -1158,7 +1155,6 @@ func (b *LocalBackend) SetControlClientStatus(c controlclient.Client, st control
 	}
 	if st.URL != "" {
 		b.authURL = st.URL
-		b.authURLSticky = st.URL
 		b.authURLTime = b.clock.Now()
 	}
 	if (wasBlocked || b.seamlessRenewalEnabled()) && st.LoginFinished() {
@@ -1276,10 +1272,8 @@ func (b *LocalBackend) SetControlClientStatus(c controlclient.Client, st control
 	}
 	if st.URL != "" {
 		b.logf("Received auth URL: %.20v...", st.URL)
-		if interact {
 		b.popBrowserAuthNow()
 	}
-	}
 	b.stateMachine()
 	// This is currently (2020-07-28) necessary; conditionally disabling it is fragile!
 	// This is where netmap information gets propagated to router and magicsock.
@@ -2281,8 +2275,8 @@ func (b *LocalBackend) WatchNotifications(ctx context.Context, mask ipn.NotifyWa
 		if mask&ipn.NotifyInitialState != 0 {
 			ini.SessionID = sessionID
 			ini.State = ptr.To(b.state)
-			if b.state == ipn.NeedsLogin && b.authURLSticky != "" {
+			if b.state == ipn.NeedsLogin && b.authURL != "" {
-				ini.BrowseToURL = ptr.To(b.authURLSticky)
+				ini.BrowseToURL = ptr.To(b.authURL)
 			}
 		}
 		if mask&ipn.NotifyInitialPrefs != 0 {
@@ -2336,11 +2330,27 @@ func (b *LocalBackend) WatchNotifications(ctx context.Context, mask ipn.NotifyWa
 	// TODO(marwan-at-work): streaming background logs?
 	defer b.DeleteForegroundSession(sessionID)
 
+	var lastURLPop string // to dup suppress URL popups
 	for {
 		select {
 		case <-ctx.Done():
 			return
 		case n, ok := <-ch:
+			// URLs flow into Notify.BrowseToURL via two means:
+			//    1. From MapResponse.PopBrowserURL, which already says they're dup
+			//       suppressed if identical, and that's done by the controlclient,
+			//       so this added later adds nothing.
+			//
+			//    2. From the controlclient auth routes, on register. This makes sure
+			//       we don't tell clients (mac, windows, android) to pop the same URL
+			//       multiple times.
+			if n != nil && n.BrowseToURL != nil {
+				if v := *n.BrowseToURL; v == lastURLPop {
+					n.BrowseToURL = nil
+				} else {
+					lastURLPop = v
+				}
+			}
 			if !ok || !fn(n) {
 				return
 			}
@@ -2476,8 +2486,6 @@ func (b *LocalBackend) sendFileNotify() {
 func (b *LocalBackend) popBrowserAuthNow() {
 	b.mu.Lock()
 	url := b.authURL
-	b.interact = false
-	b.authURL = "" // but NOT clearing authURLSticky
 	expired := b.keyExpired
 	b.mu.Unlock()
 
@@ -2805,7 +2813,6 @@ func (b *LocalBackend) StartLoginInteractive(ctx context.Context) error {
 	if b.cc == nil {
 		panic("LocalBackend.assertClient: b.cc == nil")
 	}
-	b.interact = true
 	url := b.authURL
 	timeSinceAuthURLCreated := b.clock.Since(b.authURLTime)
 	cc := b.cc
@@ -4347,7 +4354,6 @@ func (b *LocalBackend) enterStateLockedOnEntry(newState ipn.State, unlock unlock
 	authURL := b.authURL
 	if newState == ipn.Running {
 		b.authURL = ""
-		b.authURLSticky = ""
 		b.authURLTime = time.Time{}
 	} else if oldState == ipn.Running {
 		// Transitioning away from running.
@@ -4607,7 +4613,6 @@ func (b *LocalBackend) resetControlClientLocked() controlclient.Client {
 	}
 
 	b.authURL = ""
-	b.authURLSticky = ""
 
 	// When we clear the control client, stop any outstanding netmap expiry
 	// timer; synthesizing a new netmap while we don't have a control
@@ -4653,7 +4658,6 @@ func (b *LocalBackend) ResetForClientDisconnect() {
 	}
 	b.keyExpired = false
 	b.authURL = ""
-	b.authURLSticky = ""
 	b.authURLTime = time.Time{}
 	b.activeLogin = ""
 	b.resetDialPlan()

ipn/ipnlocal/state_test.go

@@ -329,7 +329,7 @@ func TestStateMachine(t *testing.T) {
 			(n.Prefs != nil && n.Prefs.Valid()) ||
 			n.BrowseToURL != nil ||
 			n.LoginFinished != nil {
-			logf("%v\n\n", n)
+			logf("%+v\n\n", n)
 			notifies.put(n)
 		} else {
 			logf("(ignored) %v\n\n", n)
@@ -406,7 +406,7 @@ func TestStateMachine(t *testing.T) {
 	// the user needs to visit a login URL.
 	t.Logf("\n\nLogin (url response)")
 
-	notifies.expect(2)
+	notifies.expect(3)
 	b.EditPrefs(&ipn.MaskedPrefs{
 		ControlURLSet: true,
 		Prefs: ipn.Prefs{
@@ -421,12 +421,15 @@ func TestStateMachine(t *testing.T) {
 		// ...but backend eats that notification, because the user
 		// didn't explicitly request interactive login yet, and
 		// we're already in NeedsLogin state.
-		nn := notifies.drain(2)
+		nn := notifies.drain(3)
 
 		c.Assert(nn[1].Prefs, qt.IsNotNil)
 		c.Assert(nn[1].Prefs.LoggedOut(), qt.IsTrue)
 		c.Assert(nn[1].Prefs.WantRunning(), qt.IsFalse)
 		c.Assert(ipn.NeedsLogin, qt.Equals, b.State())
+		c.Assert(nn[2].BrowseToURL, qt.IsNotNil)
+		c.Assert(url1, qt.Equals, *nn[2].BrowseToURL)
+		c.Assert(ipn.NeedsLogin, qt.Equals, b.State())
 	}
 
 	// Now we'll try an interactive login.
@@ -434,13 +437,10 @@ func TestStateMachine(t *testing.T) {
 	// ask control to do anything. Instead backend will emit an event
 	// indicating that the UI should browse to the given URL.
 	t.Logf("\n\nLogin (interactive)")
-	notifies.expect(1)
+	notifies.expect(0)
 	b.StartLoginInteractive(context.Background())
 	{
-		nn := notifies.drain(1)
 		cc.assertCalls()
-		c.Assert(nn[0].BrowseToURL, qt.IsNotNil)
-		c.Assert(url1, qt.Equals, *nn[0].BrowseToURL)
 		c.Assert(ipn.NeedsLogin, qt.Equals, b.State())
 	}
 
@@ -453,9 +453,8 @@ func TestStateMachine(t *testing.T) {
 	notifies.expect(0)
 	b.StartLoginInteractive(context.Background())
 	{
-		notifies.drain(0)
 		// backend asks control for another login sequence
-		cc.assertCalls("Login")
+		cc.assertCalls()
 		c.Assert(ipn.NeedsLogin, qt.Equals, b.State())
 	}