[Twisted-Python] More Conch Questions

[Colin Dunklau]

On Mon, Nov 30, 2020 at 10:21 PM Robert DiFalco <robert.difalco at gmail.com>
wrote:

> Alright, it's a but in twisted. How do I report twisted bugs? Under
> python3 service.name is bytes and not a string.
>
>
> https://github.com/twisted/twisted/blob/trunk/src/twisted/conch/client/direct.py#L86
>

https://twistedmatrix.com/trac/wiki/FrequentlyAskedQuestions#TheresabuginTwisted.WheredoIreportit

If that's the case, that comparison should throw a TypeError. Does it?


>
>
> On Mon, Nov 30, 2020 at 4:00 PM Robert DiFalco <robert.difalco at gmail.com>
> wrote:
>
>> Ok, my solution is to re-write the connect function like this. Any issues
>> with this approach?
>>
>> def connect(options, userAuthObject):
>>     d_connect = Deferred()
>>     d_authorized = Deferred()
>>
>>     factory = SFTPClientFactory(d_connect, options, userAuthObject)
>>
>>     def _connect_failed(*args, **kwargs):
>>         d_authorized.errback(args[0])
>>
>>     def _connected(*args, **kwargs):
>>         # Reset the factory's deferred
>>         factory.d = d_authorized
>>
>>     d_connect.addErrback(_connect_failed).addCallback(_connected)
>>
>>     reactor.connectTCP(options["host"], options["port"], factory)
>>
>>     return d_authorized.addCallback(lambda ignore: factory)
>>
>>
>> On Sun, Nov 29, 2020 at 9:41 AM Robert DiFalco <robert.difalco at gmail.com>
>> wrote:
>>
>>> I'm continuing to wrestle with conch, this time around authentication
>>> and notifying deferred of auth failure.
>>>
>>> It seems like the SSH factory has a deferred to be notified of auth
>>> failures here:
>>>
>>> https://github.com/twisted/twisted/blob/trunk/src/twisted/conch/client/direct.py#L61-L66
>>>
>>> Unfortunately, this deferred is cleared because prior to auth, it
>>> receives this on successful connect:
>>>
>>> https://github.com/twisted/twisted/blob/trunk/src/twisted/conch/client/direct.py#L83-L88
>>>
>>> As you can see this clears the deferred so it is no longer available to
>>> get an errback. This also prevents the SSHClientTransport from getting a
>>> sendDisconnect.
>>>
>>> To try it change the user to something invalid here:
>>> https://gist.github.com/radifalco/5a5cca4bf8d49d5c61113e36f9be7553#file-sftp-py-L328
>>>
>>> This will never get a callback to errback.
>>>
>>> I guess I would have expected this to get the error but it actually
>>> succeeds with None. As a result there is no deferred to get the auth
>>> failure and my app waits forever for a notification.
>>>
>>> There is one ting I *think* I know how to do, add a timeout with a
>>> callback later on the sftpClient deferred. But that seems lame. What I'd
>>> like to do is to get this ConchError as it has the actual reason for the
>>> connection failure.  Thoughts?
>>>
>>>
>>> https://github.com/twisted/twisted/blob/trunk/src/twisted/conch/client/direct.py#L61-L66
>>>
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