feat: add node websocket signaling relay

pkg/api/server.go

@@ -39,6 +39,7 @@ type Server struct {
 	server         *http.Server
 	nodeConnMu     sync.Mutex
 	nodeConnIDs    map[string]string
+	nodeSockets    map[string]*nodeSocketConn
 	gatewayVersion string
 	webuiVersion   string
 	configPath     string
@@ -75,9 +76,16 @@ func NewServer(host string, port int, token string, mgr *nodes.Manager) *Server
 		token:       strings.TrimSpace(token),
 		mgr:         mgr,
 		nodeConnIDs: map[string]string{},
+		nodeSockets: map[string]*nodeSocketConn{},
 	}
 }
 
+type nodeSocketConn struct {
+	connID string
+	conn   *websocket.Conn
+	mu     sync.Mutex
+}
+
 func (s *Server) SetConfigPath(path string)    { s.configPath = strings.TrimSpace(path) }
 func (s *Server) SetWorkspacePath(path string) { s.workspacePath = strings.TrimSpace(path) }
 func (s *Server) SetLogFilePath(path string)   { s.logFilePath = strings.TrimSpace(path) }
@@ -110,6 +118,21 @@ func (s *Server) rememberNodeConnection(nodeID, connID string) {
 	s.nodeConnIDs[nodeID] = connID
 }
 
+func (s *Server) bindNodeSocket(nodeID, connID string, conn *websocket.Conn) {
+	nodeID = strings.TrimSpace(nodeID)
+	connID = strings.TrimSpace(connID)
+	if nodeID == "" || connID == "" || conn == nil {
+		return
+	}
+	s.nodeConnMu.Lock()
+	prev := s.nodeSockets[nodeID]
+	s.nodeSockets[nodeID] = &nodeSocketConn{connID: connID, conn: conn}
+	s.nodeConnMu.Unlock()
+	if prev != nil && prev.connID != connID {
+		_ = prev.conn.Close()
+	}
+}
+
 func (s *Server) releaseNodeConnection(nodeID, connID string) bool {
 	nodeID = strings.TrimSpace(nodeID)
 	connID = strings.TrimSpace(connID)
@@ -122,9 +145,33 @@ func (s *Server) releaseNodeConnection(nodeID, connID string) bool {
 		return false
 	}
 	delete(s.nodeConnIDs, nodeID)
+	if sock := s.nodeSockets[nodeID]; sock != nil && sock.connID == connID {
+		delete(s.nodeSockets, nodeID)
+	}
 	return true
 }
 
+func (s *Server) getNodeSocket(nodeID string) *nodeSocketConn {
+	nodeID = strings.TrimSpace(nodeID)
+	if nodeID == "" {
+		return nil
+	}
+	s.nodeConnMu.Lock()
+	defer s.nodeConnMu.Unlock()
+	return s.nodeSockets[nodeID]
+}
+
+func (s *Server) sendNodeSocketMessage(nodeID string, msg nodes.WireMessage) error {
+	sock := s.getNodeSocket(nodeID)
+	if sock == nil || sock.conn == nil {
+		return fmt.Errorf("node %s not connected", strings.TrimSpace(nodeID))
+	}
+	sock.mu.Lock()
+	defer sock.mu.Unlock()
+	_ = sock.conn.SetWriteDeadline(time.Now().Add(10 * time.Second))
+	return sock.conn.WriteJSON(msg)
+}
+
 func (s *Server) Start(ctx context.Context) error {
 	if s.mgr == nil {
 		return nil
@@ -275,6 +322,7 @@ func (s *Server) handleNodeConnect(w http.ResponseWriter, r *http.Request) {
 			s.mgr.Upsert(*msg.Node)
 			connectedID = strings.TrimSpace(msg.Node.ID)
 			s.rememberNodeConnection(connectedID, connID)
+			s.bindNodeSocket(connectedID, connID, conn)
 			if err := writeAck(nodes.WireAck{OK: true, Type: "registered", ID: connectedID}); err != nil {
 				return
 			}
@@ -291,10 +339,12 @@ func (s *Server) handleNodeConnect(w http.ResponseWriter, r *http.Request) {
 				s.mgr.Upsert(*msg.Node)
 				connectedID = strings.TrimSpace(msg.Node.ID)
 				s.rememberNodeConnection(connectedID, connID)
+				s.bindNodeSocket(connectedID, connID, conn)
 			} else if n, ok := s.mgr.Get(id); ok {
 				s.mgr.Upsert(n)
 				connectedID = id
 				s.rememberNodeConnection(connectedID, connID)
+				s.bindNodeSocket(connectedID, connID, conn)
 			} else {
 				_ = writeAck(nodes.WireAck{OK: false, Type: "heartbeat", ID: id, Error: "node not found"})
 				continue
@@ -302,6 +352,30 @@ func (s *Server) handleNodeConnect(w http.ResponseWriter, r *http.Request) {
 			if err := writeAck(nodes.WireAck{OK: true, Type: "heartbeat", ID: connectedID}); err != nil {
 				return
 			}
+		case "signal_offer", "signal_answer", "signal_candidate":
+			if strings.TrimSpace(connectedID) == "" {
+				if err := writeAck(nodes.WireAck{OK: false, Type: msg.Type, Error: "node not registered"}); err != nil {
+					return
+				}
+				continue
+			}
+			targetID := strings.TrimSpace(msg.To)
+			if targetID == "" {
+				if err := writeAck(nodes.WireAck{OK: false, Type: msg.Type, ID: msg.ID, Error: "target node required"}); err != nil {
+					return
+				}
+				continue
+			}
+			msg.From = connectedID
+			if err := s.sendNodeSocketMessage(targetID, msg); err != nil {
+				if err := writeAck(nodes.WireAck{OK: false, Type: msg.Type, ID: msg.ID, Error: err.Error()}); err != nil {
+					return
+				}
+				continue
+			}
+			if err := writeAck(nodes.WireAck{OK: true, Type: "relayed", ID: msg.ID}); err != nil {
+				return
+			}
 		default:
 			if err := writeAck(nodes.WireAck{OK: false, Type: msg.Type, ID: msg.ID, Error: "unsupported message type"}); err != nil {
 				return