使用MSN协议运行twisted.words示例的异常

Question

我正在从位于这里的Twisted文档运行twisted.words MSN协议示例：example.py

然而，当我运行这个示例脚本时，我得到了这个UnhandledError异常：

2012-05-12 15:39:51-0300 [-] Log opened.
2012-05-12 15:39:51-0300 [-] Starting factory <twisted.internet.protocol.ClientFactory instance at  0x8c6c18c>
2012-05-12 15:39:52-0300 [Dispatch,client] Starting factory <twisted.words.protocols.msn.NotificationFactory instance at 0x8c6c2cc>
2012-05-12 15:39:52-0300 [Dispatch,client] Stopping factory <twisted.internet.protocol.ClientFactory instance at 0x8c6c18c>
2012-05-12 15:39:53-0300 [Notification,client] Starting factory <twisted.internet.protocol.ClientFactory instance at 0x8c710ec>
2012-05-12 15:39:53-0300 [Notification,client] Unhandled Error
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/twisted/python/log.py", line 84, in callWithLogger
    return callWithContext({"system": lp}, func, *args, **kw)
  File "/usr/lib/python2.7/dist-packages/twisted/python/log.py", line 69, in callWithContext
    return context.call({ILogContext: newCtx}, func, *args, **kw)
  File "/usr/lib/python2.7/dist-packages/twisted/python/context.py", line 118, in callWithContext
    return self.currentContext().callWithContext(ctx, func, *args, **kw)
  File "/usr/lib/python2.7/dist-packages/twisted/python/context.py", line 81, in callWithContext
    return func(*args,**kw)
--- <exception caught here> ---
  File "/usr/lib/python2.7/dist-packages/twisted/internet/selectreactor.py", line 146, in _doReadOrWrite
    why = getattr(selectable, method)()
  File "/usr/lib/python2.7/dist-packages/twisted/internet/tcp.py", line 460, in doRead
    rval = self.protocol.dataReceived(data)
  File "/usr/lib/python2.7/dist-packages/twisted/protocols/basic.py", line 564, in dataReceived
    why = self.lineReceived(line)
  File "/usr/lib/python2.7/dist-packages/twisted/words/protocols/msn.py", line 670, in lineReceived
    handler(params.split())
  File "/usr/lib/python2.7/dist-packages/twisted/words/protocols/msn.py", line 848, in handle_USR
    authData=params[3])
  File "/usr/lib/python2.7/dist-packages/twisted/internet/defer.py", line 108, in execute
    return succeed(result)
  File "/usr/lib/python2.7/dist-packages/twisted/internet/defer.py", line 71, in succeed
    d.callback(result)
  File "/usr/lib/python2.7/dist-packages/twisted/internet/defer.py", line 360, in callback
    assert not isinstance(result, Deferred)
exceptions.AssertionError: 

2012-05-12 15:39:53-0300 [Notification,client] Stopping factory <twisted.words.protocols.msn.NotificationFactory instance at 0x8c6c2cc>
2012-05-12 15:39:55-0300 [PassportNexus,client] Starting factory <twisted.internet.protocol.ClientFactory instance at 0x8d014cc>
2012-05-12 15:39:55-0300 [PassportNexus,client] Stopping factory <twisted.internet.protocol.ClientFactory instance at 0x8c710ec>
2012-05-12 15:39:56-0300 [PassportLogin,client] Stopping factory <twisted.internet.protocol.ClientFactory instance at 0x8d014cc>

• Python 2.7.2+
• 扭曲11.0.0
• pyOpenSSL 0.12

Answer 1

我以前从未使用过t.w.protocols.msn协议，但在我看来，在Twisted的msn.py on 第846项中有一个bug。下面是所讨论的功能：

def handle_USR(self, params):
    if len(params) != 4 and len(params) != 6:
        raise MSNProtocolError, "Invalid Number of Parameters for USR"

    mechanism = params[1]
    if mechanism == "OK":
        self.loggedIn(params[2], unquote(params[3]), int(params[4]))
    elif params[2].upper() == "S":
        # we need to obtain auth from a passport server
        f = self.factory
        d = execute(                                                   # <------- here
            _login, f.userHandle, f.password, f.passportServer,
            authData=params[3])
        d.addCallback(self._passportLogin)
        d.addErrback(self._passportError)

defer.execute与msn._login及其参数一起被调用，但是msn._login应该返回一个延迟推断。将defer.execute与可能返回延迟的函数一起使用是不合适的，因为它将立即包装到另一个通过defer.succeed推断的Deferreds中，并且Deferreds无法将其他Deferreds作为结果保存。

那里的execute调用应该使用defer.maybeDeferred。如果您将maybeDeferred添加到文件顶部的twisted.internet.defer导入中，并将此execute调用更改为maybeDeferred调用，那么它将开始工作(或者至少由于不同的bug :)而开始失败。