move ConnectionTo from Peer to LocalPeer

further shrinking the former's API

router/handshake.go

@@ -75,7 +75,7 @@ func (conn *LocalConnection) handshake(enc *gob.Encoder, dec *gob.Decoder, accep
 			return fmt.Errorf("Found unknown remote name: %s at %s", name, conn.remoteTCPAddr)
 		}
 	}
-	if existingConn, found := conn.local.ConnectionTo(name); found && existingConn.Established() {
+	if existingConn, found := conn.Router.Ourself.ConnectionTo(name); found && existingConn.Established() {
 		return fmt.Errorf("Already have connection to %s at %s", existingConn.Remote(), existingConn.RemoteTCPAddr())
 	}
 	uid, err := strconv.ParseUint(uidStr, 10, 64)

router/local_peer.go

@@ -75,6 +75,13 @@ func (peer *LocalPeer) RelayBroadcast(srcPeer *Peer, df bool, frame []byte, dec
 	}
 }
 
+func (peer *LocalPeer) ConnectionTo(name PeerName) (Connection, bool) {
+	peer.RLock()
+	defer peer.RUnlock()
+	conn, found := peer.connections[name]
+	return conn, found // yes, you really can't inline that. FFS.
+}
+
 func (peer *LocalPeer) ConnectionsTo(names []PeerName) []Connection {
 	conns := make([]Connection, 0, len(names))
 	peer.RLock()

router/peer.go

@@ -48,13 +48,6 @@ func (peer *Peer) Version() uint64 {
 	return peer.version
 }
 
-func (peer *Peer) ConnectionTo(name PeerName) (Connection, bool) {
-	peer.RLock()
-	defer peer.RUnlock()
-	conn, found := peer.connections[name]
-	return conn, found // yes, you really can't inline that. FFS.
-}
-
 func (peer *Peer) Connections() ConnectionSet {
 	connections := make(ConnectionSet)
 	peer.RLock()

router/peers_test.go

@@ -52,7 +52,7 @@ func TestPeersEncoding(t *testing.T) {
 		case 0:
 			from, to := rand.Intn(numNodes), rand.Intn(numNodes)
 			if from != to {
-				if _, found := peer[from].ConnectionTo(peer[to].Name); !found {
+				if _, found := peer[from].connections[peer[to].Name]; !found {
 					ps[from].AddTestConnection(peer[to])
 					conns = append(conns, struct{ from, to int }{from, to})
 					checkApplyUpdate(t, ps[from])

router/routes.go

@@ -231,7 +231,11 @@ func (routes *Routes) calculateBroadcast(establishedAndSymmetric bool) map[PeerN
 				if _, found := reached[remoteName]; found {
 					continue
 				}
-				if remoteConn, found := conn.Remote().ConnectionTo(ourself.Name); !establishedAndSymmetric || (found && remoteConn.Established()) {
+				// conn.Remote() cannot by ourself. Modifying
+				// peer.connections requires a write lock on Peers,
+				// and since we are holding a read lock (due to the
+				// ForEach), access without locking the peer is safe.
+				if remoteConn, found := conn.Remote().connections[ourself.Name]; !establishedAndSymmetric || (found && remoteConn.Established()) {
 					hops = append(hops, remoteName)
 				}
 			}