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>

wgengine/magicsock/endpoint.go

@@ -29,6 +29,7 @@ import (
 	"tailscale.com/tstime/mono"
 	"tailscale.com/types/key"
 	"tailscale.com/types/logger"
+	"tailscale.com/types/views"
 	"tailscale.com/util/mak"
 	"tailscale.com/util/ringbuffer"
 )
@@ -805,20 +806,38 @@ func (de *endpoint) updateFromNode(n tailcfg.NodeView, heartbeatDisabled bool) {
 		de.derpAddr = newDerp
 	}
 
+	de.setEndpointsLocked(addrPortsFromStringsView{n.Endpoints()})
+}
+
+// addrPortsFromStringsView converts a view of AddrPort strings
+// to a view-like thing of netip.AddrPort.
+// TODO(bradfitz): change the type of tailcfg.Node.Endpoint.
+type addrPortsFromStringsView struct {
+	views.Slice[string]
+}
+
+func (a addrPortsFromStringsView) At(i int) netip.AddrPort {
+	ap, _ := netip.ParseAddrPort(a.Slice.At(i))
+	return ap // or the zero value on error
+}
+
+func (de *endpoint) setEndpointsLocked(eps interface {
+	LenIter() []struct{}
+	At(i int) netip.AddrPort
+}) {
 	for _, st := range de.endpointState {
 		st.index = indexSentinelDeleted // assume deleted until updated in next loop
 	}
 
 	var newIpps []netip.AddrPort
-	for i := range n.Endpoints().LenIter() {
-		epStr := n.Endpoints().At(i)
+	for i := range eps.LenIter() {
 		if i > math.MaxInt16 {
 			// Seems unlikely.
-			continue
+			break
 		}
-		ipp, err := netip.ParseAddrPort(epStr)
-		if err != nil {
-			de.c.logf("magicsock: bogus netmap endpoint %q", epStr)
+		ipp := eps.At(i)
+		if !ipp.IsValid() {
+			de.c.logf("magicsock: bogus netmap endpoint from %v", eps)
 			continue
 		}
 		if st, ok := de.endpointState[ipp]; ok {
@@ -1214,3 +1233,9 @@ func (de *endpoint) resetLocked() {
 func (de *endpoint) numStopAndReset() int64 {
 	return atomic.LoadInt64(&de.numStopAndResetAtomic)
 }
+
+func (de *endpoint) setDERPHome(regionID uint16) {
+	de.mu.Lock()
+	defer de.mu.Unlock()
+	de.derpAddr = netip.AddrPortFrom(tailcfg.DerpMagicIPAddr, uint16(regionID))
+}

wgengine/magicsock/magicsock.go

@@ -2588,6 +2588,29 @@ func simpleDur(d time.Duration) time.Duration {
 	return d.Round(time.Minute)
 }
 
+// UpdateNetmapDelta implements controlclient.NetmapDeltaUpdater.
+func (c *Conn) UpdateNetmapDelta(muts []netmap.NodeMutation) (handled bool) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	for _, m := range muts {
+		nodeID := m.NodeIDBeingMutated()
+		ep, ok := c.peerMap.endpointForNodeID(nodeID)
+		if !ok {
+			continue
+		}
+		switch m := m.(type) {
+		case netmap.NodeMutationDERPHome:
+			ep.setDERPHome(uint16(m.DERPRegion))
+		case netmap.NodeMutationEndpoints:
+			ep.mu.Lock()
+			ep.setEndpointsLocked(views.SliceOf(m.Endpoints))
+			ep.mu.Unlock()
+		}
+	}
+	return true
+}
+
 // UpdateStatus implements the interface nede by ipnstate.StatusBuilder.
 //
 // This method adds in the magicsock-specific information only. Most