control/controlclient, types/netmap: start plumbing delta netmap updates

Currently only the top four most popular changes: endpoints, DERP
home, online, and LastSeen.

Updates #1909

Change-Id: I03152da176b2b95232b56acabfb55dcdfaa16b79
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

ipn/ipnlocal/local.go

@@ -203,9 +203,8 @@ type LocalBackend struct {
 	capFileSharing bool // whether netMap contains the file sharing capability
 	capTailnetLock bool // whether netMap contains the tailnet lock capability
 	// hostinfo is mutated in-place while mu is held.
-	hostinfo *tailcfg.Hostinfo
-	// netMap is not mutated in-place once set.
-	netMap           *netmap.NetworkMap
+	hostinfo         *tailcfg.Hostinfo
+	netMap           *netmap.NetworkMap     // not mutated in place once set (except for Peers slice)
 	nmExpiryTimer    tstime.TimerController // for updating netMap on node expiry; can be nil
 	nodeByAddr       map[netip.Addr]tailcfg.NodeView
 	activeLogin      string // last logged LoginName from netMap
@@ -1121,6 +1120,56 @@ func (b *LocalBackend) SetControlClientStatus(c controlclient.Client, st control
 	b.authReconfig()
 }
 
+var _ controlclient.NetmapDeltaUpdater = (*LocalBackend)(nil)
+
+// UpdateNetmapDelta implements controlclient.NetmapDeltaUpdater.
+func (b *LocalBackend) UpdateNetmapDelta(muts []netmap.NodeMutation) (handled bool) {
+	mc, err := b.magicConn()
+	if err != nil {
+		panic(err) // shouldn't happen
+	}
+	if !mc.UpdateNetmapDelta(muts) {
+		return false
+	}
+
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	return b.updateNetmapDeltaLocked(muts)
+}
+
+func (b *LocalBackend) updateNetmapDeltaLocked(muts []netmap.NodeMutation) (handled bool) {
+	if b.netMap == nil {
+		return false
+	}
+	peers := b.netMap.Peers
+
+	for _, m := range muts {
+		// LocalBackend only cares about some types of mutations.
+		// (magicsock cares about different ones.)
+		switch m.(type) {
+		case netmap.NodeMutationOnline, netmap.NodeMutationLastSeen:
+		default:
+			continue
+		}
+
+		nodeID := m.NodeIDBeingMutated()
+		idx := b.netMap.PeerIndexByNodeID(nodeID)
+		if idx == -1 {
+			continue
+		}
+		mut := peers[idx].AsStruct()
+
+		switch m := m.(type) {
+		case netmap.NodeMutationOnline:
+			mut.Online = ptr.To(m.Online)
+		case netmap.NodeMutationLastSeen:
+			mut.LastSeen = ptr.To(m.LastSeen)
+		}
+		peers[idx] = mut.View()
+	}
+	return true
+}
+
 // setExitNodeID updates prefs to reference an exit node by ID, rather
 // than by IP. It returns whether prefs was mutated.
 func setExitNodeID(prefs *ipn.Prefs, nm *netmap.NetworkMap) (prefsChanged bool) {

ipn/ipnlocal/local_test.go

@@ -26,6 +26,7 @@ import (
 	"tailscale.com/types/logger"
 	"tailscale.com/types/logid"
 	"tailscale.com/types/netmap"
+	"tailscale.com/types/ptr"
 	"tailscale.com/util/set"
 	"tailscale.com/wgengine"
 	"tailscale.com/wgengine/filter"
@@ -879,3 +880,75 @@ func TestWatchNotificationsCallbacks(t *testing.T) {
 		t.Fatalf("unexpected number of watchers in new LocalBackend, want: 0 got: %v", len(b.notifyWatchers))
 	}
 }
+
+// tests LocalBackend.updateNetmapDeltaLocked
+func TestUpdateNetmapDelta(t *testing.T) {
+	var b LocalBackend
+	if b.updateNetmapDeltaLocked(nil) {
+		t.Errorf("updateNetmapDeltaLocked() = true, want false with nil netmap")
+	}
+
+	b.netMap = &netmap.NetworkMap{}
+	for i := 0; i < 5; i++ {
+		b.netMap.Peers = append(b.netMap.Peers, (&tailcfg.Node{ID: (tailcfg.NodeID(i) + 1)}).View())
+	}
+
+	someTime := time.Unix(123, 0)
+	muts, ok := netmap.MutationsFromMapResponse(&tailcfg.MapResponse{
+		PeersChangedPatch: []*tailcfg.PeerChange{
+			{
+				NodeID:     1,
+				DERPRegion: 1,
+			},
+			{
+				NodeID: 2,
+				Online: ptr.To(true),
+			},
+			{
+				NodeID: 3,
+				Online: ptr.To(false),
+			},
+			{
+				NodeID:   4,
+				LastSeen: ptr.To(someTime),
+			},
+		},
+	}, someTime)
+	if !ok {
+		t.Fatal("netmap.MutationsFromMapResponse failed")
+	}
+
+	if !b.updateNetmapDeltaLocked(muts) {
+		t.Fatalf("updateNetmapDeltaLocked() = false, want true with new netmap")
+	}
+
+	wants := []*tailcfg.Node{
+		{
+			ID:   1,
+			DERP: "", // unmodified by the delta
+		},
+		{
+			ID:     2,
+			Online: ptr.To(true),
+		},
+		{
+			ID:     3,
+			Online: ptr.To(false),
+		},
+		{
+			ID:       4,
+			LastSeen: ptr.To(someTime),
+		},
+	}
+	for _, want := range wants {
+		idx := b.netMap.PeerIndexByNodeID(want.ID)
+		if idx == -1 {
+			t.Errorf("ID %v not found in netmap", want.ID)
+			continue
+		}
+		got := b.netMap.Peers[idx].AsStruct()
+		if !reflect.DeepEqual(got, want) {
+			t.Errorf("netmap.Peer %v wrong.\n got: %v\nwant: %v", want.ID, logger.AsJSON(got), logger.AsJSON(want))
+		}
+	}
+}