Question

My goal is to create telnet clients as endpoints per the TCP4ClientEndpoint implementation.

Here’s what Im doing:

class TelnetClient( TelnetProtocol ):
    ...

factory = Factory()
factory.protocol = TelnetClient
point = TCP4ClientEndpoint( reactor, x.x.x.x, 23 )
defer = point.connect( factory )

defer.addCallback( todo )
reactor.run

The TelnetClient class handles authentication, logging in, firing commands, etc.

when I use this approach, I can read some output off of dataReceived, but it’s giberish.

The telnet client functions as expected when it is constructed by a Factory and then reactor.connectTCP(...) is called with the Factory.

What is it that Im doing wrong here?

Thanks!

EDIT 1 connecting TelnetClient to factory.protocol via TelnetProtocol

class TelnetClient( TelnetProtocol ):
    ...

factory = Factory()
factory.protocol = TelnetTransport( TelnetClient )
point = TCP4ClientEndpoint( reactor, x.x.x.x, 23 )
defer = point.connect( factory )

defer.addCallback( todo )
reactor.run

EDIT 2 solved. The final piece was ClientFactory.

class TelnetClient( TelnetProtocol ):
    ...

factory = ClientFactory()
factory.protocol = TelnetTransport( TelnetClient )
point = TCP4ClientEndpoint( reactor, x.x.x.x, 23 )
defer = point.connect( factory )

Solving this problem was two fold.

1. Since we want a telnet client, we need to ensure that the protocol is an instance of TelnetProtocol.

2. The factory must be of ClientFactory. If we look at the source of twisted.internet.endoints, we see that the factory we pass in to the endpoints is wrapped in _WrappingFactory, which is descended from ClientFactory. If this factory we pass in does not have the same attributes as ClientFactory, then the _wrappedFactory will cause AttributeErrors when it attempts to call methods of ClientFactory

Answer 1

You’re correct thatconnectTCP and endpoint.connect are functionally the same (for the most part).

Assuming that TelnetProtocol is twisted.conch.telnet.TelnetProtocol, the problem here is that TelnetProtocol is not really supposed to connect directly to a TCP transport, it’s supposed to connect to a twisted.conch.telnet.TelnetTransport. That “gibberish” in dataReceived that you’re seeing are the actual telnet protocol bytes, which are supposed to be parsed by a twisted.conch.telnet.TelnetTransport (which is itself an IProtocol) in order to call methods like enableLocal and enableRemote on the TelnetTransport.

I would guess that in your connectTCP-based example, you are probably instantiating a TelnetTransport and setting its .protocol attribute to point at a TelnetProtocol.

Basically, make sure that the Factory object that you’re passing in has exactly the same protocol attribute as the ClientFactory you’re using in your connectTCP example.

In the future, also, please include complete, runnable code examples so that we can run them and see what happens rather than guessing :-).