LocalConnection shouldn't have to know about remote UDP address

...and generally know less about how overlays establish connectivity.

router/connection.go

@@ -190,16 +190,11 @@ func (conn *LocalConnection) run(actionChan <-chan ConnectionAction, finished ch
 
 	conn.Log("connection ready; using protocol version", conn.version)
 
-	var remoteAddr *net.UDPAddr
-	if conn.outbound {
-		tcpAddr := conn.TCPConn.RemoteAddr().(*net.TCPAddr)
-		remoteAddr = &net.UDPAddr{IP: tcpAddr.IP, Port: tcpAddr.Port, Zone: tcpAddr.Zone}
-	}
-
 	params := ForwarderParams{
 		RemotePeer:         conn.remote,
-		LocalIP:            conn.TCPConn.LocalAddr().(*net.TCPAddr).IP,
-		RemoteAddr:         remoteAddr,
+		LocalAddr:          conn.TCPConn.LocalAddr().(*net.TCPAddr),
+		RemoteAddr:         conn.TCPConn.RemoteAddr().(*net.TCPAddr),
+		Outbound:           conn.outbound,
 		ConnUID:            conn.uid,
 		Crypto:             conn.forwarderCrypto(),
 		SendControlMessage: conn.sendOverlayControlMessage,

router/fastdp.go

@@ -523,15 +523,16 @@ func (fastdp fastDatapathOverlay) MakeForwarder(params ForwarderParams) (Overlay
 	}
 
 	vxlanVportID := fastdp.mainVxlanVportID
-	remoteAddr := params.RemoteAddr
-	if remoteAddr != nil {
+	var remoteAddr *net.UDPAddr
+
+	if params.Outbound {
+		remoteAddr = makeUDPAddr(params.RemoteAddr)
 		// The provided address contains the main weave port
 		// number to connect to.  We need to derive the vxlan
 		// port number from that.
-		vxlanRemoteAddr := *params.RemoteAddr
+		vxlanRemoteAddr := *remoteAddr
 		vxlanRemoteAddr.Port++
 		remoteAddr = &vxlanRemoteAddr
-
 		var err error
 		vxlanVportID, err = fastdp.getVxlanVportID(remoteAddr.Port)
 		if err != nil {
@@ -539,7 +540,7 @@ func (fastdp fastDatapathOverlay) MakeForwarder(params ForwarderParams) (Overlay
 		}
 	}
 
-	localIP, err := ipv4Bytes(params.LocalIP)
+	localIP, err := ipv4Bytes(params.LocalAddr.IP)
 	if err != nil {
 		return nil, err
 	}

router/overlay.go

@@ -29,15 +29,19 @@ type Overlay interface {
 type ForwarderParams struct {
 	RemotePeer *Peer
 
-	// The local IP address to use for sending.  Derived from the
-	// local address of the corresponding TCP socket, so may
-	// differ for different forwarders.
-	LocalIP net.IP
+	// The local address of the corresponding TCP connection. Used to
+	// derive the local IP address for sending. May differ for
+	// different forwarders.
+	LocalAddr *net.TCPAddr
 
-	// The remote address to send to.  nil if unknown, i.e. an
-	// incoming connection, in which case the Overlay needs to
-	// discover it (e.g. from incoming datagrams).
-	RemoteAddr *net.UDPAddr
+	// The remote address of the corresponding TCP connection. Used to
+	// determine the address to send to, but only if the TCP
+	// connection is outbound. Otherwise the Overlay needs to discover
+	// it (e.g. from incoming datagrams).
+	RemoteAddr *net.TCPAddr
+
+	// Is the corresponding TCP connection outbound?
+	Outbound bool
 
 	// Unique identifier for this connection
 	ConnUID uint64

router/sleeve.go

@@ -365,6 +365,11 @@ func (sleeve *SleeveOverlay) MakeForwarder(params ForwarderParams) (OverlayForwa
 	confirmedChan := make(chan struct{})
 	finishedChan := make(chan struct{})
 
+	var remoteAddr *net.UDPAddr
+	if params.Outbound {
+		remoteAddr = makeUDPAddr(params.RemoteAddr)
+	}
+
 	fwd := &sleeveForwarder{
 		sleeve:           sleeve,
 		remotePeer:       params.RemotePeer,
@@ -379,13 +384,13 @@ func (sleeve *SleeveOverlay) MakeForwarder(params ForwarderParams) (OverlayForwa
 		finishedChan:     finishedChan,
 		establishedChan:  make(chan struct{}),
 		errorChan:        make(chan error, 1),
-		remoteAddr:       params.RemoteAddr,
+		remoteAddr:       remoteAddr,
 		mtu:              DefaultMTU,
 		crypto:           crypto,
 		maxPayload:       DefaultMTU - UDPOverhead,
 		overheadDF: UDPOverhead + crypto.EncDF.PacketOverhead() +
 			crypto.EncDF.FrameOverhead() + EthernetOverhead,
-		senderDF: newUDPSenderDF(params.LocalIP, sleeve.localPort),
+		senderDF: newUDPSenderDF(params.LocalAddr.IP, sleeve.localPort),
 	}
 
 	go fwd.run(aggChan, aggDFChan, specialChan, controlMsgChan,

router/utils.go

@@ -104,6 +104,10 @@ func intmac(key uint64) (r net.HardwareAddr) {
 	return
 }
 
+func makeUDPAddr(addr *net.TCPAddr) *net.UDPAddr {
+	return &net.UDPAddr{IP: addr.IP, Port: addr.Port, Zone: addr.Zone}
+}
+
 type ListOfPeers []*Peer
 
 func (lop ListOfPeers) Len() int {