feat: implement initial client-server tunnel with WebSocket, custom protocol, and comprehensive proxy handling.

internal/server/tunnel/websocket.go

@@ -0,0 +1,146 @@
+package tunnel
+
+import (
+	"io"
+	"log"
+	"net"
+	"net/http"
+	"time"
+
+	"github.com/gorilla/websocket"
+	"github.com/gotunnel/pkg/protocol"
+	"github.com/gotunnel/pkg/relay"
+)
+
+var upgrader = websocket.Upgrader{
+	CheckOrigin: func(r *http.Request) bool {
+		return true // 允许所有跨域请求
+	},
+}
+
+// WSConnAdapter 适配器：将 websocket.Conn 适配为 io.ReadWriter
+type WSConnAdapter struct {
+	conn *websocket.Conn
+	// 读缓冲
+	reader io.Reader
+}
+
+func NewWSConnAdapter(conn *websocket.Conn) *WSConnAdapter {
+	return &WSConnAdapter{
+		conn: conn,
+	}
+}
+
+func (a *WSConnAdapter) Read(p []byte) (n int, err error) {
+	if a.reader == nil {
+		messageType, reader, err := a.conn.NextReader()
+		if err != nil {
+			return 0, err
+		}
+		if messageType != websocket.BinaryMessage && messageType != websocket.TextMessage {
+			// 忽略非数据消息
+			return 0, nil
+		}
+		a.reader = reader
+	}
+	n, err = a.reader.Read(p)
+	if err == io.EOF {
+		a.reader = nil
+		err = nil // 当前消息读完，不代表连接断开
+		// 如果读到了0字节，尝试读下一个消息，避免因为返回 (0, nil) 导致调用方以为无数据空转
+		if n == 0 {
+			return a.Read(p)
+		}
+	}
+	return n, err
+}
+
+func (a *WSConnAdapter) Write(p []byte) (n int, err error) {
+	err = a.conn.WriteMessage(websocket.BinaryMessage, p)
+	if err != nil {
+		return 0, err
+	}
+	return len(p), nil
+}
+
+func (a *WSConnAdapter) Close() error {
+	return a.conn.Close()
+}
+
+func (a *WSConnAdapter) LocalAddr() net.Addr {
+	return a.conn.LocalAddr()
+}
+
+func (a *WSConnAdapter) RemoteAddr() net.Addr {
+	return a.conn.RemoteAddr()
+}
+
+func (a *WSConnAdapter) SetDeadline(t time.Time) error {
+	if err := a.conn.SetReadDeadline(t); err != nil {
+		return err
+	}
+	return a.conn.SetWriteDeadline(t)
+}
+
+func (a *WSConnAdapter) SetReadDeadline(t time.Time) error {
+	return a.conn.SetReadDeadline(t)
+}
+
+func (a *WSConnAdapter) SetWriteDeadline(t time.Time) error {
+	return a.conn.SetWriteDeadline(t)
+}
+
+// acceptWebsocketConns 接受 Websocket 连接
+func (s *Server) acceptWebsocketConns(cs *ClientSession, ln net.Listener, rule protocol.ProxyRule) {
+	mux := http.NewServeMux()
+	mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		wsConn, err := upgrader.Upgrade(w, r, nil)
+		if err != nil {
+			log.Printf("[Server] Websocket upgrade error: %v", err)
+			return
+		}
+
+		conn := NewWSConnAdapter(wsConn)
+		// 这里的 conn 并没有实现 net.Conn 接口的全部方法 (LocalAddr, RemoteAddr 等)，
+		// Relay 函数如果需要 net.Conn，可能需要更完整的适配器。
+		// 查看 relay.Relay 签名：func Relay(c1, c2 io.ReadWriteCloser)
+		// 假设 relay.Relay 接受 io.ReadWriteCloser。
+
+		go s.handleWebsocketProxyConn(cs, conn, rule)
+	})
+
+	server := &http.Server{
+		Handler:      mux,
+		ReadTimeout:  10 * time.Second,
+		WriteTimeout: 10 * time.Second,
+	}
+
+	// 这里不需要协程，因为 startProxyListeners 中已经是 go s.acceptWebsocketConns(...) 调用了？
+	// 不，startProxyListeners 中 iterate rules。如果是 acceptWebsocketConns，应该是在那里 go。
+	// 检查 caller 逻辑。
+
+	if err := server.Serve(ln); err != nil && err != http.ErrServerClosed {
+		log.Printf("[Server] Websocket server error: %v", err)
+	}
+}
+
+// handleWebsocketProxyConn 处理 Websocket 代理连接
+func (s *Server) handleWebsocketProxyConn(cs *ClientSession, conn net.Conn, rule protocol.ProxyRule) {
+	defer conn.Close()
+
+	stream, err := cs.Session.Open()
+	if err != nil {
+		log.Printf("[Server] Open stream error: %v", err)
+		return
+	}
+	defer stream.Close()
+
+	// 发送新代理连接请求，告知客户端连接到哪里
+	req := protocol.NewProxyRequest{RemotePort: rule.RemotePort}
+	msg, _ := protocol.NewMessage(protocol.MsgTypeNewProxy, req)
+	if err := protocol.WriteMessage(stream, msg); err != nil {
+		return
+	}
+
+	relay.Relay(conn, stream)
+}