server: update genNodeAnnouncement to also write new node ann to disk

In this commit, we update the genNodeAnnouncement method to also write
an updated version of the node announcment to disk. Before this commit,
we would update the in memory version, but then never write the new
version to disk. As a result, when connecting to new peers, we would
never propagate the new version of this announcement to the network.

server.go

@@ -1526,32 +1526,59 @@ func (s *server) genNodeAnnouncement(refresh bool,
 	s.mu.Lock()
 	defer s.mu.Unlock()
 
+	// If we don't need to refresh the announcement, then we can return a
+	// copy of our cached version.
 	if !refresh {
 		return *s.currentNodeAnn, nil
 	}
 
+	// Now that we know we need to update our copy, we'll apply all the
+	// function updates that'll mutate the current version of our node
+	// announcement.
 	for _, update := range updates {
 		update(s.currentNodeAnn)
 	}
 
+	// We'll now update the timestamp, ensuring that with each update, the
+	// timestamp monotonically increases.
 	newStamp := uint32(time.Now().Unix())
 	if newStamp <= s.currentNodeAnn.Timestamp {
 		newStamp = s.currentNodeAnn.Timestamp + 1
 	}
-
 	s.currentNodeAnn.Timestamp = newStamp
+
+	// Now that the announce tn is fully updated, we'll generate a new
+	// signature over the announcement to ensure nodes on the network
+	// accepted the new authenticated announcement.
 	sig, err := discovery.SignAnnouncement(
 		s.nodeSigner, s.identityPriv.PubKey(), s.currentNodeAnn,
 	)
 	if err != nil {
 		return lnwire.NodeAnnouncement{}, err
 	}
-
 	s.currentNodeAnn.Signature, err = lnwire.NewSigFromSignature(sig)
 	if err != nil {
 		return lnwire.NodeAnnouncement{}, err
 	}
 
+	// Finally, we'll update the on-disk version of our announcement so it
+	// will eventually propagate to nodes in the network.
+	selfNode := &channeldb.LightningNode{
+		HaveNodeAnnouncement: true,
+		LastUpdate:           time.Unix(int64(s.currentNodeAnn.Timestamp), 0),
+		Addresses:            s.currentNodeAnn.Addresses,
+		Alias:                s.currentNodeAnn.Alias.String(),
+		Features: lnwire.NewFeatureVector(
+			s.currentNodeAnn.Features, lnwire.GlobalFeatures,
+		),
+		Color:        s.currentNodeAnn.RGBColor,
+		AuthSigBytes: sig.Serialize(),
+	}
+	if err := s.chanDB.ChannelGraph().SetSourceNode(selfNode); err != nil {
+		return *s.currentNodeAnn, fmt.Errorf("can't set self node: %v",
+			err)
+	}
+
 	return *s.currentNodeAnn, nil
 }