A variety of fixes to try combat the multicast issue

tunnel/default.go

@@ -502,22 +502,26 @@ func (t *tun) listen(link *link) {
 			// TODO: handle the close message
 			// maybe report io.EOF or kill the link
 
-			// close the link entirely
+			// if there is no channel then we close the link
+			// as its a signal from the other side to close the connection
 			if len(channel) == 0 {
 				log.Debugf("Tunnel link %s received close message", link.Remote())
 				return
 			}
 
-			// the entire listener was closed so remove it from the mapping
+			// the entire listener was closed by the remote side so we need to
+			// remove the channel mapping for it. should we also close sessions?
 			if sessionId == "listener" {
 				link.delChannel(channel)
 				continue
 			}
 
+			// assuming there's a channel and session
 			// try get the dialing socket
-			_, exists := t.getSession(channel, sessionId)
-			if exists {
-				// delete and continue
+			s, exists := t.getSession(channel, sessionId)
+			if exists && s.mode == Unicast && !loopback {
+				// only delete this if its unicast
+				// but not if its a loopback conn
 				t.delSession(channel, sessionId)
 				continue
 			}
@@ -673,6 +677,7 @@ func (t *tun) listen(link *link) {
 			typ:      mtype,
 			channel:  channel,
 			session:  sessionId,
+			mode:     s.mode,
 			data:     tmsg,
 			link:     link.id,
 			loopback: loopback,
@@ -703,7 +708,7 @@ func (t *tun) discover(link *link) {
 					"Micro-Tunnel-Id": t.id,
 				},
 			}); err != nil {
-				log.Debugf("Tunnel failed to send discover to link %s: %v", link.id, err)
+				log.Debugf("Tunnel failed to send discover to link %s: %v", link.Remote(), err)
 			}
 		case <-link.closed:
 			return

tunnel/listener.go

@@ -88,7 +88,7 @@ func (t *tunListener) process() {
 					// the link the message was received on
 					link: m.link,
 					// set the connection mode
-					mode: t.session.mode,
+					mode: m.mode,
 					// close chan
 					closed: make(chan bool),
 					// recv called by the acceptor

tunnel/session.go

@@ -413,11 +413,6 @@ func (s *session) Close() error {
 	default:
 		close(s.closed)
 
-		// don't broadcast the close for multicast
-		if s.mode != Unicast {
-			return nil
-		}
-
 		// append to backlog
 		msg := s.newMessage("close")
 		// no error response on close