feat: introduce a new robust approach to handle tproxy udp. (#389)

listener/sing/sing.go

@@ -166,3 +166,11 @@ func (c *packet) Drop() {
 func (c *packet) InAddr() net.Addr {
 	return c.lAddr
 }
+
+func (c *packet) SetNatTable(natTable C.NatTable) {
+	// no need
+}
+
+func (c *packet) SetUdpInChan(in chan<- C.PacketAdapter) {
+	// no need
+}