Use sync.Pool for obfuscation buffer

internal/multiplex/session.go

@@ -70,6 +70,8 @@ type Session struct {
 	// a pool of heap allocated frame objects so we don't have to allocate a new one each time we receive a frame
 	recvFramePool sync.Pool
 
+	streamObfsBufPool sync.Pool
+
 	// Switchboard manages all connections to remote
 	sb *switchboard
 
@@ -117,6 +119,11 @@ func MakeSession(id uint32, config SessionConfig) *Session {
 	// todo: validation. this must be smaller than StreamSendBufferSize
 	sesh.maxStreamUnitWrite = sesh.MsgOnWireSizeLimit - frameHeaderLength - sesh.Obfuscator.maxOverhead
 
+	sesh.streamObfsBufPool = sync.Pool{New: func() interface{} {
+		b := make([]byte, sesh.StreamSendBufferSize)
+		return &b
+	}}
+
 	sesh.sb = makeSwitchboard(sesh)
 	time.AfterFunc(sesh.InactivityTimeout, sesh.checkTimeout)
 	return sesh
@@ -180,25 +187,20 @@ func (sesh *Session) closeStream(s *Stream, active bool) error {
 	_ = s.getRecvBuf().Close() // recvBuf.Close should not return error
 
 	if active {
-		tmpBuf := make([]byte, 256+frameHeaderLength+sesh.Obfuscator.maxOverhead)
+		tmpBuf := sesh.streamObfsBufPool.Get().(*[]byte)
 
 		// Notify remote that this stream is closed
-		common.CryptoRandRead(tmpBuf[:1])
-		padLen := int(tmpBuf[0]) + 1
-		payload := tmpBuf[frameHeaderLength : padLen+frameHeaderLength]
+		common.CryptoRandRead((*tmpBuf)[:1])
+		padLen := int((*tmpBuf)[0]) + 1
+		payload := (*tmpBuf)[frameHeaderLength : padLen+frameHeaderLength]
 		common.CryptoRandRead(payload)
 
 		// must be holding s.wirtingM on entry
 		s.writingFrame.Closing = closingStream
 		s.writingFrame.Payload = payload
 
-		cipherTextLen, err := sesh.Obfs(&s.writingFrame, tmpBuf, frameHeaderLength)
-		s.writingFrame.Seq++
-		if err != nil {
-			return err
-		}
-
-		_, err = sesh.sb.send(tmpBuf[:cipherTextLen], &s.assignedConnId)
+		err := s.obfuscateAndSend(*tmpBuf, frameHeaderLength)
+		sesh.streamObfsBufPool.Put(tmpBuf)
 		if err != nil {
 			return err
 		}

internal/multiplex/stream.go

@@ -34,11 +34,6 @@ type Stream struct {
 	// atomic
 	closed uint32
 
-	// obfuscation happens in obfsBuf. This buffer is lazily allocated as obfsBuf is only used when data is sent from
-	// the stream (through Write or ReadFrom). Some streams never send data so eager allocation will waste
-	// memory
-	obfsBuf []byte
-
 	// When we want order guarantee (i.e. session.Unordered is false),
 	// we assign each stream a fixed underlying connection.
 	// If the underlying connections the session uses provide ordering guarantee (most likely TCP),
@@ -117,13 +112,14 @@ func (s *Stream) WriteTo(w io.Writer) (int64, error) {
 	return n, nil
 }
 
-func (s *Stream) obfuscateAndSend(payloadOffsetInObfsBuf int) error {
-	cipherTextLen, err := s.session.Obfs(&s.writingFrame, s.obfsBuf, payloadOffsetInObfsBuf)
+func (s *Stream) obfuscateAndSend(buf []byte, payloadOffsetInBuf int) error {
+	cipherTextLen, err := s.session.Obfs(&s.writingFrame, buf, payloadOffsetInBuf)
+	s.writingFrame.Seq++
 	if err != nil {
 		return err
 	}
 
-	_, err = s.session.sb.send(s.obfsBuf[:cipherTextLen], &s.assignedConnId)
+	_, err = s.session.sb.send(buf[:cipherTextLen], &s.assignedConnId)
 	if err != nil {
 		if err == errBrokenSwitchboard {
 			s.session.SetTerminalMsg(err.Error())
@@ -142,9 +138,6 @@ func (s *Stream) Write(in []byte) (n int, err error) {
 		return 0, ErrBrokenStream
 	}
 
-	if s.obfsBuf == nil {
-		s.obfsBuf = make([]byte, s.session.StreamSendBufferSize)
-	}
 	for n < len(in) {
 		var framePayload []byte
 		if len(in)-n <= s.session.maxStreamUnitWrite {
@@ -160,8 +153,9 @@ func (s *Stream) Write(in []byte) (n int, err error) {
 			framePayload = in[n : s.session.maxStreamUnitWrite+n]
 		}
 		s.writingFrame.Payload = framePayload
-		err = s.obfuscateAndSend(0)
-		s.writingFrame.Seq++
+		buf := s.session.streamObfsBufPool.Get().(*[]byte)
+		err = s.obfuscateAndSend(*buf, 0)
+		s.session.streamObfsBufPool.Put(buf)
 		if err != nil {
 			return
 		}
@@ -173,9 +167,6 @@ func (s *Stream) Write(in []byte) (n int, err error) {
 // ReadFrom continuously read data from r and send it off, until either r returns error or nothing has been read
 // for readFromTimeout amount of time
 func (s *Stream) ReadFrom(r io.Reader) (n int64, err error) {
-	if s.obfsBuf == nil {
-		s.obfsBuf = make([]byte, s.session.StreamSendBufferSize)
-	}
 	for {
 		if s.readFromTimeout != 0 {
 			if rder, ok := r.(net.Conn); !ok {
@@ -184,7 +175,8 @@ func (s *Stream) ReadFrom(r io.Reader) (n int64, err error) {
 				rder.SetReadDeadline(time.Now().Add(s.readFromTimeout))
 			}
 		}
-		read, er := r.Read(s.obfsBuf[frameHeaderLength : frameHeaderLength+s.session.maxStreamUnitWrite])
+		buf := s.session.streamObfsBufPool.Get().(*[]byte)
+		read, er := r.Read((*buf)[frameHeaderLength : frameHeaderLength+s.session.maxStreamUnitWrite])
 		if er != nil {
 			return n, er
 		}
@@ -196,10 +188,10 @@ func (s *Stream) ReadFrom(r io.Reader) (n int64, err error) {
 		}
 
 		s.writingM.Lock()
-		s.writingFrame.Payload = s.obfsBuf[frameHeaderLength : frameHeaderLength+read]
-		err = s.obfuscateAndSend(frameHeaderLength)
-		s.writingFrame.Seq++
+		s.writingFrame.Payload = (*buf)[frameHeaderLength : frameHeaderLength+read]
+		err = s.obfuscateAndSend(*buf, frameHeaderLength)
 		s.writingM.Unlock()
+		s.session.streamObfsBufPool.Put(buf)
 
 		if err != nil {
 			return