Refactor: new Shadowsocks validator (#629)

* Refactor: new Shadowsocks validator

* Fix NoneCliper cannot work

* Feat: refine the size of drain

* fix: fix validator after merge 'main'

* fix: UDP user logic

* style: refine code style

proxy/shadowsocks/server.go

@@ -115,10 +115,6 @@ func (s *Server) handleUDPPayload(ctx context.Context, conn stat.Connection, dis
 		panic("no inbound metadata")
 	}
 
-	if s.validator.Count() == 1 {
-		inbound.User, _ = s.validator.GetOnlyUser()
-	}
-
 	var dest *net.Destination
 
 	reader := buf.NewPacketReader(conn)