Scapy：如何匹配查询和答案

Question

我正在Scapy中实现一个协议，这是我迄今为止所做的（详细信息省略）：

class Protocol - #Defines some common headers
    def guess_payload_class:
        return ProtocolAction1

class ProtocolAction1 - #Defines some action to be done by the protocol.


class ProtocolAnswer - #Defines some common headers
    def guess_payload_class:
        return ProtocolAction1Anser

class ProtocolAction1Answer - #Defines the answer when Action1 has been done.

bind_layers(UDP, Protocol, dport=port)
bind_layers(UDP, ProtocolAnswer, sport=port)

但是，当我执行sr(IP()/UDP()/Protocol()/ProtocolAction1())时，我永远无法得到答案（尽管服务器发送了它）。我的目的是获得IP()/UDP()/ProtocolAnswer()/ProtocolAction1Answer()。我做错了什么，我该如何解决？