fix a regression that mux doesn't handle passive connection. fixes #1061

app/proxyman/mux/mux.go

@@ -144,6 +144,19 @@ func (m *Client) monitor() {
 	}
 }
 
+func copyFirstPayload(reader *pipe.Reader, writer *Writer) error {
+	data, err := reader.ReadMultiBufferWithTimeout(time.Millisecond * 200)
+	if err == buf.ErrReadTimeout {
+		return writer.writeMetaOnly()
+	}
+
+	if err != nil {
+		return err
+	}
+
+	return writer.WriteMultiBuffer(data)
+}
+
 func fetchInput(ctx context.Context, s *Session, output buf.Writer) {
 	dest, _ := proxy.TargetFromContext(ctx)
 	transferType := protocol.TransferTypeStream
@@ -153,14 +166,22 @@ func fetchInput(ctx context.Context, s *Session, output buf.Writer) {
 	s.transferType = transferType
 	writer := NewWriter(s.ID, dest, output, transferType)
 	defer s.Close()
+	defer writer.Close()
 
 	newError("dispatching request to ", dest).WithContext(ctx).WriteToLog()
+	if pReader, ok := s.input.(*pipe.Reader); ok {
+		if err := copyFirstPayload(pReader, writer); err != nil {
+			newError("failed to fetch first payload").Base(err).WithContext(ctx).WriteToLog()
+			writer.hasError = true
+			return
+		}
+	}
+
 	if err := buf.Copy(s.input, writer); err != nil {
 		newError("failed to fetch all input").Base(err).WithContext(ctx).WriteToLog()
 		writer.hasError = true
+		return
 	}
-
-	writer.Close()
 }
 
 func (m *Client) Dispatch(ctx context.Context, link *core.Link) bool {