[Twisted-Python] More Conch Questions

[Robert DiFalco]

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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