fix: chrome requests hanging over port-forward (#4588)

agent/agent.go

@@ -879,12 +879,22 @@ func (r *reconnectingPTY) Close() {
 // after one or both of them are done writing. If the context is canceled, both
 // of the connections will be closed.
 func Bicopy(ctx context.Context, c1, c2 io.ReadWriteCloser) {
-	defer c1.Close()
-	defer c2.Close()
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	defer func() {
+		_ = c1.Close()
+		_ = c2.Close()
+	}()
 
 	var wg sync.WaitGroup
 	copyFunc := func(dst io.WriteCloser, src io.Reader) {
-		defer wg.Done()
+		defer func() {
+			wg.Done()
+			// If one side of the copy fails, ensure the other one exits as
+			// well.
+			cancel()
+		}()
 		_, _ = io.Copy(dst, src)
 	}
 

cli/portforward.go

@@ -138,8 +138,7 @@ func portForward() *cobra.Command {
 				case <-ctx.Done():
 					closeErr = ctx.Err()
 				case <-sigs:
-					_, _ = fmt.Fprintln(cmd.OutOrStderr(), "Received signal, closing all listeners and active connections")
-					closeErr = xerrors.New("signal received")
+					_, _ = fmt.Fprintln(cmd.OutOrStderr(), "\nReceived signal, closing all listeners and active connections")
 				}
 
 				cancel()
@@ -213,7 +212,11 @@ func listenAndPortForward(ctx context.Context, cmd *cobra.Command, conn *codersd
 		for {
 			netConn, err := l.Accept()
 			if err != nil {
-				_, _ = fmt.Fprintf(cmd.OutOrStderr(), "Error accepting connection from '%v://%v': %+v\n", spec.listenNetwork, spec.listenAddress, err)
+				// Silently ignore net.ErrClosed errors.
+				if xerrors.Is(err, net.ErrClosed) {
+					return
+				}
+				_, _ = fmt.Fprintf(cmd.OutOrStderr(), "Error accepting connection from '%v://%v': %v\n", spec.listenNetwork, spec.listenAddress, err)
 				_, _ = fmt.Fprintln(cmd.OutOrStderr(), "Killing listener")
 				return
 			}