[Twisted-Python] problem enhancing conch sample

[Henning.Ramm at mediapro-gmbh.de]

Hello again!

Last time I had the same problem with a telnet client; I dropped the code to start again with the conch ssh sample. I'm trying to find a way to execute more than one command, but I seem to mistunderstand something fundamental, at least the server closes the connection always after the first command.

This is my code, derived closely (and a bit simplified) from the example:

#!/usr/bin/env python
from twisted.conch.ssh import transport, userauth, connection, common, keys, channel
from twisted.internet import defer, protocol, reactor
from twisted.python import log
import struct, sys, getpass, os

USER = 'me'  # replace this with a valid username
PASS = 'mypass' # password
HOST = 'localhost' # and a valid host

class SimpleTransport(transport.SSHClientTransport):
    def verifyHostKey(self, hostKey, fingerprint):
        # print 'host key fingerprint: %s' % fingerprint
        return defer.succeed(1)

    def connectionSecure(self):
        self.requestService(
            SimpleUserAuth(USER,
                SimpleConnection()))

class SimpleUserAuth(userauth.SSHUserAuthClient):
    def getPassword(self):
        return defer.succeed(PASS)

    def getGenericAnswers(self, name, instruction, questions):
        print name
        print instruction
        answers = []
        for prompt, echo in questions:
            if echo:
                answer = raw_input(prompt)
            else:
                answer = getpass.getpass(prompt)
            answers.append(answer)
        return defer.succeed(answers)

    def getPublicKey(self):
	  return None

    def getPrivateKey(self):
	  return None

class SimpleConnection(connection.SSHConnection):
    def serviceStarted(self):
        self.openChannel(CatChannel(2**16, 2**15, self))

class CatChannel(channel.SSHChannel):
    name = 'session'
    cmd = 'pwd'
    commands = ['pwd','cd /','ls -al','exit']
    pointer = 0

    def openFailed(self, reason):
        print 'echo failed', reason

    def channelOpen(self, ignoredData):
        self.data = ''
        reactor.callLater(0, self.sendNextRequest)

    def sendNextRequest(self):
        cmd = self.commands[self.pointer]
        print cmd
        d = self.conn.sendRequest(self, 'exec', common.NS(cmd), wantReply = 1)
        d.addCallback(self._cbRequest)
        d.addErrback(log.msg)

    def _cbRequest(self, ignored):
        self.write('hello conch\n') # any sense?
        self.pointer += 1
        if self.commands[self.pointer] == 'exit':
            self.conn.sendEOF(self)
        else:
            reactor.callLater(0, self.sendNextRequest)

    def dataReceived(self, data):
        self.data += data

    def closed(self):
        print 'got data: %s' % repr(self.data)
        self.loseConnection()
        reactor.stop()

def twisted_logger(logdict):
    text = " ".join([str(m) for m in logdict["message"]])
    prompt = '.>'
    if logdict['isError'] or 'error' in text.lower():
        prompt = "!>"
    print prompt, text

log.addObserver(twisted_logger)
protocol.ClientCreator(reactor, SimpleTransport).connectTCP(HOST, 22)
reactor.run()



Sorry if you already tried to help me last time, seems like I didn't get it...

Best regards,
Henning Hraban Ramm
Südkurier Medienhaus / MediaPro
Support/Admin/Development Dept.