swallow write error in mux

app/proxyman/mux/mux.go

@@ -175,22 +175,10 @@ func (m *Client) Dispatch(ctx context.Context, outboundRay ray.OutboundRay) bool
 }
 
 func drain(reader *Reader) error {
-	data, err := reader.Read()
-	if err != nil {
-		return err
-	}
-	data.Release()
+	buf.Copy(signal.BackgroundTimer(), reader, buf.Discard)
 	return nil
 }
 
-func pipe(reader *Reader, writer buf.Writer) error {
-	data, err := reader.Read()
-	if err != nil {
-		return err
-	}
-	return writer.Write(data)
-}
-
 func (m *Client) handleStatueKeepAlive(meta *FrameMetadata, reader *Reader) error {
 	if meta.Option.Has(OptionData) {
 		return drain(reader)
@@ -211,7 +199,7 @@ func (m *Client) handleStatusKeep(meta *FrameMetadata, reader *Reader) error {
 	}
 
 	if s, found := m.sessionManager.Get(meta.SessionID); found {
-		return pipe(reader, s.output)
+		return buf.Copy(signal.BackgroundTimer(), reader, s.output, buf.IgnoreWriterError())
 	}
 	return drain(reader)
 }
@@ -335,7 +323,7 @@ func (w *ServerWorker) handleStatusNew(ctx context.Context, meta *FrameMetadata,
 	w.sessionManager.Add(s)
 	go handle(ctx, s, w.outboundRay.OutboundOutput())
 	if meta.Option.Has(OptionData) {
-		return pipe(reader, s.output)
+		return buf.Copy(signal.BackgroundTimer(), reader, s.output, buf.IgnoreWriterError())
 	}
 	return nil
 }
@@ -345,7 +333,7 @@ func (w *ServerWorker) handleStatusKeep(meta *FrameMetadata, reader *Reader) err
 		return nil
 	}
 	if s, found := w.sessionManager.Get(meta.SessionID); found {
-		return pipe(reader, s.output)
+		return buf.Copy(signal.BackgroundTimer(), reader, s.output, buf.IgnoreWriterError())
 	}
 	return drain(reader)
 }

app/proxyman/mux/reader.go

@@ -8,18 +8,22 @@ import (
 )
 
 type Reader struct {
-	reader io.Reader
-	buffer *buf.Buffer
+	reader   io.Reader
+	buffer   *buf.Buffer
+	leftOver int
 }
 
 func NewReader(reader buf.Reader) *Reader {
 	return &Reader{
-		reader: buf.ToBytesReader(reader),
-		buffer: buf.NewLocal(1024),
+		reader:   buf.ToBytesReader(reader),
+		buffer:   buf.NewLocal(1024),
+		leftOver: -1,
 	}
 }
 
 func (r *Reader) ReadMetadata() (*FrameMetadata, error) {
+	r.leftOver = -1
+
 	b := r.buffer
 	b.Clear()
 
@@ -37,25 +41,43 @@ func (r *Reader) ReadMetadata() (*FrameMetadata, error) {
 	return ReadFrameFrom(b.Bytes())
 }
 
-func (r *Reader) Read() (buf.MultiBuffer, error) {
+func (r *Reader) readSize() error {
 	if err := r.buffer.Reset(buf.ReadFullFrom(r.reader, 2)); err != nil {
-		return nil, err
+		return err
+	}
+	r.leftOver = int(serial.BytesToUint16(r.buffer.Bytes()))
+	return nil
+}
+
+func (r *Reader) Read() (buf.MultiBuffer, error) {
+	if r.leftOver == 0 {
+		r.leftOver = -1
+		return nil, io.EOF
+	}
+	if r.leftOver == -1 {
+		if err := r.readSize(); err != nil {
+			return nil, err
+		}
 	}
 
-	dataLen := int(serial.BytesToUint16(r.buffer.Bytes()))
 	mb := buf.NewMultiBuffer()
-	for dataLen > 0 {
+	for r.leftOver > 0 {
 		readLen := buf.Size
-		if dataLen < readLen {
-			readLen = dataLen
+		if r.leftOver < readLen {
+			readLen = r.leftOver
 		}
 		b := buf.New()
-		if err := b.AppendSupplier(buf.ReadFullFrom(r.reader, readLen)); err != nil {
+		if err := b.AppendSupplier(func(bb []byte) (int, error) {
+			return r.reader.Read(bb[:readLen])
+		}); err != nil {
 			mb.Release()
 			return nil, err
 		}
-		dataLen -= readLen
+		r.leftOver -= b.Len()
 		mb.Append(b)
+		if b.Len() < readLen {
+			break
+		}
 	}
 
 	return mb, nil

common/buf/io.go

@@ -47,13 +47,40 @@ func ReadAtLeastFrom(reader io.Reader, size int) Supplier {
 	}
 }
 
-func copyInternal(timer signal.ActivityTimer, reader Reader, writer Writer) error {
+type copyHandler struct {
+	onReadError  func(error) error
+	onData       func()
+	onWriteError func(error) error
+}
+
+type CopyOption func(*copyHandler)
+
+func IgnoreReaderError() CopyOption {
+	return func(handler *copyHandler) {
+		handler.onReadError = func(err error) error {
+			return nil
+		}
+	}
+}
+
+func IgnoreWriterError() CopyOption {
+	return func(handler *copyHandler) {
+		handler.onWriteError = func(err error) error {
+			return nil
+		}
+	}
+}
+
+func copyInternal(timer signal.ActivityTimer, reader Reader, writer Writer, handler copyHandler) error {
 	for {
 		buffer, err := reader.Read()
 		if err != nil {
-			return err
+			if err = handler.onReadError(err); err != nil {
+				return err
+			}
 		}
 
+		handler.onData()
 		timer.Update()
 
 		if buffer.IsEmpty() {
@@ -62,16 +89,22 @@ func copyInternal(timer signal.ActivityTimer, reader Reader, writer Writer) erro
 		}
 
 		if err := writer.Write(buffer); err != nil {
-			buffer.Release()
-			return err
+			if err = handler.onWriteError(err); err != nil {
+				buffer.Release()
+				return err
+			}
 		}
 	}
 }
 
 // Copy dumps all payload from reader to writer or stops when an error occurs.
 // ActivityTimer gets updated as soon as there is a payload.
-func Copy(timer signal.ActivityTimer, reader Reader, writer Writer) error {
-	err := copyInternal(timer, reader, writer)
+func Copy(timer signal.ActivityTimer, reader Reader, writer Writer, options ...CopyOption) error {
+	handler := copyHandler{}
+	for _, option := range options {
+		option(&handler)
+	}
+	err := copyInternal(timer, reader, writer, handler)
 	if err != nil && errors.Cause(err) != io.EOF {
 		return err
 	}

common/buf/writer.go

@@ -106,3 +106,14 @@ func (w *bytesToBufferWriter) ReadFrom(reader io.Reader) (int64, error) {
 	}
 	return totalBytes, nil
 }
+
+type noOpWriter struct{}
+
+func (noOpWriter) Write(b MultiBuffer) error {
+	b.Release()
+	return nil
+}
+
+var (
+	Discard Writer = noOpWriter{}
+)