Fix WireGuard client bind

transport/wireguard/client_bind.go

@@ -88,8 +88,7 @@ func (c *ClientBind) connect() (*wireConn, error) {
 func (c *ClientBind) Open(port uint16) (fns []conn.ReceiveFunc, actualPort uint16, err error) {
 	select {
 	case <-c.done:
-		err = net.ErrClosed
-		return
+		c.done = make(chan struct{})
 	default:
 	}
 	return []conn.ReceiveFunc{c.receive}, 0, nil
@@ -165,7 +164,7 @@ func (c *ClientBind) Send(bufs [][]byte, ep conn.Endpoint) error {
 			}
 			copy(b[1:4], reserved[:])
 		}
-		_, err = udpConn.WriteTo(b, M.SocksaddrFromNetIP(destination))
+		_, err = udpConn.WriteToUDPAddrPort(b, destination)
 		if err != nil {
 			udpConn.Close()
 			return err
@@ -192,10 +191,18 @@ func (c *ClientBind) SetReservedForEndpoint(destination netip.AddrPort, reserved
 
 type wireConn struct {
 	net.PacketConn
+	conn   net.Conn
 	access sync.Mutex
 	done   chan struct{}
 }
 
+func (w *wireConn) WriteToUDPAddrPort(b []byte, addr netip.AddrPort) (int, error) {
+	if w.conn != nil {
+		return w.conn.Write(b)
+	}
+	return w.PacketConn.WriteTo(b, M.SocksaddrFromNetIP(addr).UDPAddr())
+}
+
 func (w *wireConn) Close() error {
 	w.access.Lock()
 	defer w.access.Unlock()