使用Twisted记录SMTP连接

Logging SMTP connections with Twisted(使用Twisted记录SMTP连接)

问题描述

这里是Python新手。我正在使用Twisted和twisted.mail.smtp编写一个SMTP服务器。我想记录传入的连接，并可能在有太多并发连接时将其转储。基本上，我希望在建立新连接时在以下位置调用ConsoleMessageDelivery.ConnectionMade()方法：

class ConsoleMessageDelivery:
    implements(smtp.IMessageDelivery)

    def connectionMade(self):
        # This never gets called

    def receivedHeader(self, helo, origin, recipients):
        myHostname, clientIP = helo
        headerValue = "by %s from %s with ESMTP ; %s" % (myHostname, clientIP, smtp.rfc822date())
        # email.Header.Header used for automatic wrapping of long lines
        return "Received: %s" % Header(headerValue)

    def validateFrom(self, helo, origin):
        # All addresses are accepted
        return origin

    def validateTo(self, user):
        if user.dest.local == "console":
            return lambda: ConsoleMessage()
        raise smtp.SMTPBadRcpt(user)

class ConsoleMessage:
    implements(smtp.IMessage)

    def __init__(self):
        self.lines = []

    def lineReceived(self, line):
        self.lines.append(line)

    def eomReceived(self):
        return defer.succeed(None)

    def connectionLost(self):
        # There was an error, throw away the stored lines
        self.lines = None

class ConsoleSMTPFactory(smtp.SMTPFactory):
    protocol = smtp.ESMTP

    def __init__(self, *a, **kw):
        smtp.SMTPFactory.__init__(self, *a, **kw)
        self.delivery = ConsoleMessageDelivery()

    def buildProtocol(self, addr):
        p = smtp.SMTPFactory.buildProtocol(self, addr)
        p.delivery = self.delivery
        return p

推荐答案

connectionMade是twisted.internet.interfaces.IProtocol的一部分，不是twisted.mail.smtp.IMessageDelivery的一部分。邮件服务器实现中没有任何代码关心消息传递实现上的connectionMade方法。

将每个连接逻辑放在工厂中更好。具体地说，解决这一问题的一个好方法是使用工厂包装器，将有关连接限制和日志记录的逻辑与有关服务SMTP连接的逻辑隔离。

from twisted.protocols.policies import LimitConnectionsByPeer
...
factory = ConsoleSMTPFactory()
wrapper = LimitConnectionsByPeer(ConsoleSMTPFactory(...))
reactor.listenTCP(465, wrapper)

from twisted.protocols.policies import WrappingFactory

class DenyFactory(WrappingFactory):
    def buildProtocol(self, clientAddress):
        if clientAddress.host == '1.3.3.7':
            # Reject it
            return None
         # Accept everything else
         return WrappingFactory.buildProtocol(self, clientAddress)

from twisted.protocols.policies import LimitConnectionsByPeer
...
factory = ConsoleSMTPFactory()
wrapper = LimitConnectionsByPeer(DenyFactory(ConsoleSMTPFactory(...)))
reactor.listenTCP(465, wrapper)