server: update persistent peer addrs from announcements

In this commit, a subscription is made to topology updates. For any
NodeAnnouncements received for our peristent peers, we store their newly
advertised addresses. If at the time of receiving these new addresses
there are any existing connection requests, these are updated to reflect
the newly advertised addresses.

lntest/itest/lnd_network_test.go

@@ -221,10 +221,10 @@ func testReconnectAfterIPChange(net *lntest.NetworkHarness, t *harnessTest) {
 		[]string{fmt.Sprintf("127.0.0.1:%d", dave.Cfg.P2PPort)},
 	)
 
-	// assert that Dave and Charlie do not reconnect after Dave changes
-	// his P2P address to one not listed in Dave's original advertised list
-	// of addresses. This is a bug that will be fixed in a follow-up commit.
-	assertNotConnected(t, dave, charlie)
+	// assert that Dave and Charlie do reconnect after Dave changes his P2P
+	// address to one not listed in Dave's original advertised list of
+	// addresses.
+	assertConnected(t, dave, charlie)
 }
 
 // assertTimeoutError asserts that a connection timeout error is raised. A

server.go

@@ -309,6 +309,89 @@ type server struct {
 	wg sync.WaitGroup
 }
 
+// updatePersistentPeerAddrs subscribes to topology changes and stores
+// advertised addresses for any NodeAnnouncements from our persisted peers.
+func (s *server) updatePersistentPeerAddrs() error {
+	graphSub, err := s.chanRouter.SubscribeTopology()
+	if err != nil {
+		return err
+	}
+
+	s.wg.Add(1)
+	go func() {
+		defer func() {
+			graphSub.Cancel()
+			s.wg.Done()
+		}()
+
+		for {
+			select {
+
+			case <-s.quit:
+				return
+
+			case topChange, ok := <-graphSub.TopologyChanges:
+				// If the router is shutting down, then we will
+				// as well.
+				if !ok {
+					return
+				}
+
+				for _, update := range topChange.NodeUpdates {
+					pubKeyStr := string(
+						update.IdentityKey.
+							SerializeCompressed(),
+					)
+
+					// We only care about updates from
+					// our persistentPeers.
+					s.mu.RLock()
+					_, ok := s.persistentPeers[pubKeyStr]
+					s.mu.RUnlock()
+					if !ok {
+						continue
+					}
+
+					addrs := make([]*lnwire.NetAddress, 0,
+						len(update.Addresses))
+
+					for _, addr := range update.Addresses {
+						addrs = append(addrs,
+							&lnwire.NetAddress{
+								IdentityKey: update.IdentityKey,
+								Address:     addr,
+								ChainNet:    s.cfg.ActiveNetParams.Net,
+							},
+						)
+					}
+
+					s.mu.Lock()
+
+					// Update the stored addresses for this
+					// to peer to reflect the new set.
+					s.persistentPeerAddrs[pubKeyStr] = addrs
+
+					// If there are no outstanding
+					// connection requests for this peer
+					// then our work is done since we are
+					// not currently trying to connect to
+					// them.
+					if len(s.persistentConnReqs[pubKeyStr]) == 0 {
+						s.mu.Unlock()
+						continue
+					}
+
+					s.mu.Unlock()
+
+					s.connectToPersistentPeer(pubKeyStr)
+				}
+			}
+		}
+	}()
+
+	return nil
+}
+
 // parseAddr parses an address from its string format to a net.Addr.
 func parseAddr(address string, netCfg tor.Net) (net.Addr, error) {
 	var (
@@ -1742,6 +1825,13 @@ func (s *server) Start() error {
 			return nil
 		})
 
+		// Subscribe to NodeAnnouncements that advertise new addresses
+		// our persistent peers.
+		if err := s.updatePersistentPeerAddrs(); err != nil {
+			startErr = err
+			return
+		}
+
 		// With all the relevant sub-systems started, we'll now attempt
 		// to establish persistent connections to our direct channel
 		// collaborators within the network. Before doing so however,