Rename variables for clarity

internal/multiplex/stream.go

@@ -13,11 +13,18 @@ import (
 
 var ErrBrokenStream = errors.New("broken stream")
 
+// Stream implements net.Conn. It represents an optionally-ordered, full-duplex, self-contained connection.
+// If the session it belongs to runs in ordered mode, it provides ordering guarantee regardless of the underlying
+// connection used.
+// If the underlying connections the session uses are reliable, Stream is reliable. If they are not, Stream does not
+// guarantee reliability.
 type Stream struct {
 	id uint32
 
 	session *Session
 
+	// a buffer (implemented as an asynchronous buffered pipe) to put data we've received from recvFrame but hasn't
+	// been read by the consumer through Read or WriteTo
 	recvBuf recvBuffer
 
 	nextSendSeq uint64
@@ -34,13 +41,15 @@ type Stream struct {
 	// obfuscation happens in this buffer
 	obfsBuf []byte
 
-	// we assign each stream a fixed underlying TCP connection to utilise order guarantee provided by TCP itself
-	// so that frameSorter should have few to none ooo frames to deal with
-	// overall the streams in a session should be uniformly distributed across all connections
+	// 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),
+	// recvBuffer (implemented by streamBuffer under ordered mode) will not receive out-of-order packets
+	// so it won't have to use its priority queue to sort it.
 	// This is not used in unordered connection mode
 	assignedConnId uint32
 
-	rfTimeout time.Duration
+	readFromTimeout time.Duration
 }
 
 func makeStream(sesh *Session, id uint32) *Stream {
@@ -91,6 +100,7 @@ func (s *Stream) Read(buf []byte) (n int, err error) {
 	return
 }
 
+// WriteTo continuously write data Stream has received into the writer w.
 func (s *Stream) WriteTo(w io.Writer) (int64, error) {
 	// will keep writing until the underlying buffer is closed
 	n, err := s.recvBuf.WriteTo(w)
@@ -101,9 +111,9 @@ func (s *Stream) WriteTo(w io.Writer) (int64, error) {
 	return n, nil
 }
 
-func (s *Stream) sendFrame(f *Frame, framePayloadOffset int) error {
+func (s *Stream) obfuscateAndSend(f *Frame, payloadOffsetInObfsBuf int) error {
 	var cipherTextLen int
-	cipherTextLen, err := s.session.Obfs(f, s.obfsBuf, framePayloadOffset)
+	cipherTextLen, err := s.session.Obfs(f, s.obfsBuf, payloadOffsetInObfsBuf)
 	if err != nil {
 		return err
 	}
@@ -134,9 +144,12 @@ func (s *Stream) Write(in []byte) (n int, err error) {
 	for n < len(in) {
 		var framePayload []byte
 		if len(in)-n <= s.session.maxStreamUnitWrite {
+			// if we can fit remaining data of in into one frame
 			framePayload = in[n:]
 		} else {
-			if s.session.Unordered { // no splitting
+			// if we have to split
+			if s.session.Unordered {
+				// but we are not allowed to
 				err = io.ErrShortBuffer
 				return
 			}
@@ -149,7 +162,7 @@ func (s *Stream) Write(in []byte) (n int, err error) {
 			Payload:  framePayload,
 		}
 		s.nextSendSeq++
-		err = s.sendFrame(f, 0)
+		err = s.obfuscateAndSend(f, 0)
 		if err != nil {
 			return
 		}
@@ -158,16 +171,18 @@ func (s *Stream) Write(in []byte) (n int, err error) {
 	return
 }
 
+// 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.rfTimeout != 0 {
+		if s.readFromTimeout != 0 {
 			if rder, ok := r.(net.Conn); !ok {
 				log.Warn("ReadFrom timeout is set but reader doesn't implement SetReadDeadline")
 			} else {
-				rder.SetReadDeadline(time.Now().Add(s.rfTimeout))
+				rder.SetReadDeadline(time.Now().Add(s.readFromTimeout))
 			}
 		}
 		read, er := r.Read(s.obfsBuf[HEADER_LEN : HEADER_LEN+s.session.maxStreamUnitWrite])
@@ -186,7 +201,7 @@ func (s *Stream) ReadFrom(r io.Reader) (n int64, err error) {
 			Payload:  s.obfsBuf[HEADER_LEN : HEADER_LEN+read],
 		}
 		s.nextSendSeq++
-		err = s.sendFrame(f, HEADER_LEN)
+		err = s.obfuscateAndSend(f, HEADER_LEN)
 		s.writingM.Unlock()
 
 		if err != nil {
@@ -211,14 +226,14 @@ func (s *Stream) Close() error {
 func (s *Stream) LocalAddr() net.Addr  { return s.session.addrs.Load().([]net.Addr)[0] }
 func (s *Stream) RemoteAddr() net.Addr { return s.session.addrs.Load().([]net.Addr)[1] }
 
-// TODO: implement the following
 func (s *Stream) SetWriteToTimeout(d time.Duration)  { s.recvBuf.SetWriteToTimeout(d) }
 func (s *Stream) SetReadDeadline(t time.Time) error  { s.recvBuf.SetReadDeadline(t); return nil }
-func (s *Stream) SetReadFromTimeout(d time.Duration) { s.rfTimeout = d }
+func (s *Stream) SetReadFromTimeout(d time.Duration) { s.readFromTimeout = d }
+
+var errNotImplemented = errors.New("Not implemented")
 
 // the following functions are purely for implementing net.Conn interface.
 // they are not used
-var errNotImplemented = errors.New("Not implemented")
-
+// TODO: implement the following
 func (s *Stream) SetDeadline(t time.Time) error      { return errNotImplemented }
 func (s *Stream) SetWriteDeadline(t time.Time) error { return errNotImplemented }

internal/multiplex/switchboard.go

@@ -64,7 +64,7 @@ func (sb *switchboard) addConn(conn net.Conn) {
 	go sb.deplex(connId, conn)
 }
 
-// a pointer to connId is passed here so that the switchboard can reassign it
+// a pointer to connId is passed here so that the switchboard can reassign it if that connId isn't usable
 func (sb *switchboard) send(data []byte, connId *uint32) (n int, err error) {
 	writeAndRegUsage := func(conn net.Conn, d []byte) (int, error) {
 		n, err = conn.Write(d)