add tunnel handler and connector

connector/relay/conn.go

@@ -209,3 +209,16 @@ func (c *bindUDPConn) RemoteAddr() net.Addr {
 func (c *bindUDPConn) Metadata() mdata.Metadata {
 	return c.md
 }
+
+type bindAddr struct {
+	network string
+	addr    string
+}
+
+func (p *bindAddr) Network() string {
+	return p.network
+}
+
+func (p *bindAddr) String() string {
+	return p.addr
+}