extendable protocol

Signed-off-by: He Xian <[email protected]>

v3/handler.go

@@ -51,16 +51,21 @@ func (h *TLSHandler) Serve(ctx context.Context, conn net.Conn) {
 	} else {
 		slog.Warningf("%q <= %v: connection is not encrypted", h.t.tag, conn.RemoteAddr())
 	}
+	req, err := proto.RecvRequest(conn)
+	if err != nil {
+		slog.Errorf("%q <= %v: %s", h.t.tag, conn.RemoteAddr(), formats.Error(err))
+		return
+	}
 	t := h.t
-	req := &proto.ServerHello{
+	rsp := &proto.ServerMsg{
 		Type:    proto.Type,
+		Msg:     proto.MsgHello,
 		Service: c.RemoteService,
 	}
 	if t.c.RemoteService != "" {
-		req.Service = t.c.RemoteService
+		rsp.Service = t.c.RemoteService
 	}
-	rsp, err := proto.Server(conn, req)
-	if err != nil {
+	if err := proto.SendResponse(conn, rsp); err != nil {
 		slog.Errorf("%q <= %v: %s", h.t.tag, conn.RemoteAddr(), formats.Error(err))
 		return
 	}
@@ -71,11 +76,11 @@ func (h *TLSHandler) Serve(ctx context.Context, conn net.Conn) {
 		return
 	}
 	h.s.stats.authorized.Add(1)
-	if rsp.Service != "" {
-		if tun := h.s.findTunnel(rsp.Service); tun != nil {
+	if req.Service != "" {
+		if tun := h.s.findTunnel(req.Service); tun != nil {
 			t = tun
 		} else {
-			slog.Infof("%q <= %v: unknown service %q", t.tag, conn.RemoteAddr(), req.Service)
+			slog.Infof("%q <= %v: unknown service %q", t.tag, conn.RemoteAddr(), rsp.Service)
 		}
 	}
 	t.addMux(mux, false)

v3/proto/proto.go

@@ -11,14 +11,20 @@ import (
 
 const Type = "application/x-tlswrapper; version=3"
 
-type ClientHello struct {
+const (
+	MsgHello = iota
+)
+
+type ClientMsg struct {
 	Type    string `json:"type"`
-	Service string `json:"service"`
+	Msg     int    `json:"msgid"`
+	Service string `json:"service,omitempty"`
 }
 
-type ServerHello struct {
+type ServerMsg struct {
 	Type    string `json:"type"`
-	Service string `json:"service"`
+	Msg     int    `json:"msgid"`
+	Service string `json:"service,omitempty"`
 }
 
 var (
@@ -57,11 +63,11 @@ func recvmsg(conn net.Conn, msg interface{}) error {
 	return nil
 }
 
-func Client(conn net.Conn, req *ClientHello) (*ServerHello, error) {
+func Roundtrip(conn net.Conn, req *ClientMsg) (*ServerMsg, error) {
 	if err := sendmsg(conn, req); err != nil {
 		return nil, err
 	}
-	rsp := &ServerHello{}
+	rsp := &ServerMsg{}
 	if err := recvmsg(conn, rsp); err != nil {
 		return nil, err
 	}
@@ -71,16 +77,17 @@ func Client(conn net.Conn, req *ClientHello) (*ServerHello, error) {
 	return rsp, nil
 }
 
-func Server(conn net.Conn, rsp *ServerHello) (*ClientHello, error) {
-	req := &ClientHello{}
+func RecvRequest(conn net.Conn) (*ClientMsg, error) {
+	req := &ClientMsg{}
 	if err := recvmsg(conn, req); err != nil {
 		return nil, err
 	}
 	if req.Type != Type {
 		return nil, ErrUnsupportedProtocol
 	}
-	if err := sendmsg(conn, rsp); err != nil {
-		return nil, err
-	}
 	return req, nil
 }
+
+func SendResponse(conn net.Conn, rsp *ServerMsg) error {
+	return sendmsg(conn, rsp)
+}

v3/tunnel.go

@@ -262,14 +262,15 @@ func (t *Tunnel) dial(ctx context.Context) (*yamux.Session, error) {
 	} else {
 		slog.Warningf("%q => %v: connection is not encrypted", t.tag, conn.RemoteAddr())
 	}
-	req := &proto.ClientHello{
+	req := &proto.ClientMsg{
 		Type:    proto.Type,
+		Msg:     proto.MsgHello,
 		Service: c.RemoteService,
 	}
 	if t.c.RemoteService != "" {
 		req.Service = t.c.RemoteService
 	}
-	rsp, err := proto.Client(conn, req)
+	rsp, err := proto.Roundtrip(conn, req)
 	if err != nil {
 		return nil, err
 	}