TUN-2955: Fix connection and goroutine leaks when tunnel conection is terminated on error. Only unregister tunnels that had connected successfully. Close edge connection used to unregister the tunnel. Use buffered channels for error channels where receiver may quit early on context cancellation.

carrier/carrier.go

@@ -79,7 +79,11 @@ func Serve(remoteConn Connection, listener net.Listener, shutdownC <-chan struct
 		for {
 			conn, err := listener.Accept()
 			if err != nil {
-				errChan <- err
+				// don't block if parent goroutine quit early
+				select {
+				case errChan <- err:
+				default:
+				}
 				return
 			}
 			go serveConnection(remoteConn, conn, options)

h2mux/h2mux.go

@@ -206,9 +206,9 @@ func Handshake(
 		initialStreamWindow:     m.config.DefaultWindowSize,
 		streamWindowMax:         m.config.MaxWindowSize,
 		streamWriteBufferMaxLen: m.config.StreamWriteBufferMaxLen,
-		r:                       m.r,
-		metricsUpdater:          m.muxMetricsUpdater,
-		bytesRead:               inBoundCounter,
+		r:              m.r,
+		metricsUpdater: m.muxMetricsUpdater,
+		bytesRead:      inBoundCounter,
 	}
 	m.muxWriter = &MuxWriter{
 		f:               m.f,
@@ -327,7 +327,11 @@ func (m *Muxer) Serve(ctx context.Context) error {
 			m.explicitShutdown.Fuse(false)
 			m.r.Close()
 			m.abort()
-			ch <- err
+			// don't block if parent goroutine quit early
+			select {
+			case ch <- err:
+			default:
+			}
 		}()
 		select {
 		case err := <-ch:
@@ -344,7 +348,11 @@ func (m *Muxer) Serve(ctx context.Context) error {
 			m.explicitShutdown.Fuse(false)
 			m.w.Close()
 			m.abort()
-			ch <- err
+			// don't block if parent goroutine quit early
+			select {
+			case ch <- err:
+			default:
+			}
 		}()
 		select {
 		case err := <-ch:
@@ -358,7 +366,11 @@ func (m *Muxer) Serve(ctx context.Context) error {
 		ch := make(chan error)
 		go func() {
 			err := m.muxMetricsUpdater.run(m.config.Logger)
-			ch <- err
+			// don't block if parent goroutine quit early
+			select {
+			case ch <- err:
+			default:
+			}
 		}()
 		select {
 		case err := <-ch:

origin/tunnel.go

@@ -322,7 +322,10 @@ func ServeTunnel(
 			select {
 			case <-serveCtx.Done():
 				// UnregisterTunnel blocks until the RPC call returns
-				err := UnregisterTunnel(handler.muxer, config.GracePeriod, config.TransportLogger)
+				var err error
+				if connectedFuse.Value() {
+					err = UnregisterTunnel(handler.muxer, config.GracePeriod, config.TransportLogger)
+				}
 				handler.muxer.Shutdown()
 				return err
 			case <-updateMetricsTickC:
@@ -519,6 +522,8 @@ func UnregisterTunnel(muxer *h2mux.Muxer, gracePeriod time.Duration, logger *log
 		// RPC stream open error
 		return err
 	}
+	defer tunnelServer.Close()
+
 	// gracePeriod is encoded in int64 using capnproto
 	return tunnelServer.UnregisterTunnel(ctx, gracePeriod.Nanoseconds())
 }

tunnelrpc/pogs/tunnelrpc.go

@@ -521,6 +521,7 @@ type TunnelServer_PogsClient struct {
 }
 
 func (c TunnelServer_PogsClient) Close() error {
+	c.Client.Close()
 	return c.Conn.Close()
 }
 

watcher/file.go

@@ -30,7 +30,11 @@ func (f *File) Add(filepath string) error {
 
 // Shutdown stop the file watching run loop
 func (f *File) Shutdown() {
-	f.shutdown <- struct{}{}
+	// don't block if Start quit early
+	select {
+	case f.shutdown <- struct{}{}:
+	default:
+	}
 }
 
 // Start is a runloop to watch for files changes from the file paths added from Add()