pass metadata along with stream creation command

session.go

@@ -80,7 +80,7 @@ func newSession(config *Config, conn io.ReadWriteCloser, client bool) *Session {
 }
 
 // OpenStream is used to create a new stream
-func (s *Session) OpenStream() (*Stream, error) {
+func (s *Session) OpenStream(metadata ...byte) (*Stream, error) {
 	if s.IsClosed() {
 		return nil, errors.New(errBrokenPipe)
 	}
@@ -101,9 +101,11 @@ func (s *Session) OpenStream() (*Stream, error) {
 	}
 	s.nextStreamIDLock.Unlock()
 
-	stream := newStream(sid, s.config.MaxFrameSize, s)
+	stream := newStream(sid, metadata, s.config.MaxFrameSize, s)
 
-	if _, err := s.writeFrame(newFrame(cmdSYN, sid)); err != nil {
+	frame := newFrame(cmdSYN, sid)
+	frame.data = metadata
+	if _, err := s.writeFrame(frame); err != nil {
 		return nil, errors.Wrap(err, "writeFrame")
 	}
 
@@ -247,7 +249,7 @@ func (s *Session) recvLoop() {
 			case cmdSYN:
 				s.streamLock.Lock()
 				if _, ok := s.streams[f.sid]; !ok {
-					stream := newStream(f.sid, s.config.MaxFrameSize, s)
+					stream := newStream(f.sid, f.data, s.config.MaxFrameSize, s)
 					s.streams[f.sid] = stream
 					select {
 					case s.chAccepts <- stream:

session_test.go

@@ -1,6 +1,7 @@
 package smux
 
 import (
+	"bytes"
 	crand "crypto/rand"
 	"encoding/binary"
 	"fmt"
@@ -16,7 +17,7 @@ import (
 // setupServer starts new server listening on a random localhost port and
 // returns address of the server, function to stop the server, new client
 // connection to this server or an error.
-func setupServer(tb testing.TB) (addr string, stopfunc func(), client net.Conn, err error) {
+func setupServer(tb testing.TB, metadata ...byte) (addr string, stopfunc func(), client net.Conn, err error) {
 	ln, err := net.Listen("tcp", "localhost:0")
 	if err != nil {
 		return "", nil, nil, err
@@ -27,7 +28,7 @@ func setupServer(tb testing.TB) (addr string, stopfunc func(), client net.Conn,
 			tb.Error(err)
 			return
 		}
-		go handleConnection(conn)
+		go handleConnection(tb, conn, metadata...)
 	}()
 	addr = ln.Addr().String()
 	conn, err := net.Dial("tcp", addr)
@@ -38,10 +39,13 @@ func setupServer(tb testing.TB) (addr string, stopfunc func(), client net.Conn,
 	return ln.Addr().String(), func() { ln.Close() }, conn, nil
 }
 
-func handleConnection(conn net.Conn) {
+func handleConnection(tb testing.TB, conn net.Conn, metadata ...byte) {
 	session, _ := Server(conn, nil)
 	for {
 		if stream, err := session.AcceptStream(); err == nil {
+			if !bytes.Equal(metadata, stream.Metadata()) {
+				tb.Fatal("metadata mimatch")
+			}
 			go func(s io.ReadWriteCloser) {
 				buf := make([]byte, 65536)
 				for {
@@ -58,6 +62,18 @@ func handleConnection(conn net.Conn) {
 	}
 }
 
+func TestMetadata(t *testing.T) {
+	metadata := []byte("hello, world")
+	_, stop, cli, err := setupServer(t, metadata...)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer stop()
+	session, _ := Client(cli, nil)
+	session.OpenStream(metadata...)
+	session.Close()
+}
+
 func TestEcho(t *testing.T) {
 	_, stop, cli, err := setupServer(t)
 	if err != nil {

stream.go

@@ -14,6 +14,7 @@ import (
 // Stream implements net.Conn
 type Stream struct {
 	id            uint32
+	metadata      []byte
 	rstflag       int32
 	sess          *Session
 	buffer        bytes.Buffer
@@ -27,9 +28,10 @@ type Stream struct {
 }
 
 // newStream initiates a Stream struct
-func newStream(id uint32, frameSize int, sess *Session) *Stream {
+func newStream(id uint32, metadata []byte, frameSize int, sess *Session) *Stream {
 	s := new(Stream)
 	s.id = id
+	s.metadata = metadata
 	s.chReadEvent = make(chan struct{}, 1)
 	s.frameSize = frameSize
 	s.sess = sess
@@ -42,6 +44,11 @@ func (s *Stream) ID() uint32 {
 	return s.id
 }
 
+// Metadata returns stream metadata which was provided when opening stream.
+func (s *Stream) Metadata() []byte {
+	return s.metadata
+}
+
 // Read implements net.Conn
 func (s *Stream) Read(b []byte) (n int, err error) {
 	if len(b) == 0 {