Sorry I have not been able to find a better title, please see the
attached example which may be more descriptive.
Here is what it does:
* set up an SSH connection
* open a TCP forwarding channel through this connection
* do something through the tunnel that will trigger an errback (in the
example, try to do an XMLRPC call with no one listening on the
tunnel's end)
This scenario gives me the following traceback (tested with Twisted
8.1.0 and 8.2.0):
-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-
File
"/usr/lib/python2.5/site-packages/Twisted-8.2.0-py2.5-linux-i686.egg/twisted/python/log.py",
line 84, in callWithLogger
return callWithContext({"system": lp}, func, *args, **kw)
File
"/usr/lib/python2.5/site-packages/Twisted-8.2.0-py2.5-linux-i686.egg/twisted/python/log.py",
line 69, in callWithContext
return context.call({ILogContext: newCtx}, func, *args, **kw)
File
"/usr/lib/python2.5/site-packages/Twisted-8.2.0-py2.5-linux-i686.egg/twisted/python/context.py",
line 59, in callWithContext
return self.currentContext().callWithContext(ctx, func, *args, **kw)
File
"/usr/lib/python2.5/site-packages/Twisted-8.2.0-py2.5-linux-i686.egg/twisted/python/context.py",
line 37, in callWithContext
return func(*args,**kw)
File
"/usr/lib/python2.5/site-packages/Twisted-8.2.0-py2.5-linux-i686.egg/twisted/internet/selectreactor.py",
line 156, in _doReadOrWrite
self._disconnectSelectable(selectable, why, method=="doRead")
File
"/usr/lib/python2.5/site-packages/Twisted-8.2.0-py2.5-linux-i686.egg/twisted/internet/posixbase.py",
line 193, in _disconnectSelectable
selectable.connectionLost(f)
File
"/usr/lib/python2.5/site-packages/Twisted-8.2.0-py2.5-linux-i686.egg/twisted/internet/tcp.py",
line 520, in connectionLost
protocol.connectionLost(reason)
File
"/usr/lib/python2.5/site-packages/Twisted-8.2.0-py2.5-linux-i686.egg/twisted/conch/ssh/forwarding.py",
line 129, in connectionLost
self.channel.loseConnection()
File
"/usr/lib/python2.5/site-packages/Twisted-8.2.0-py2.5-linux-i686.egg/twisted/conch/ssh/channel.py",
line 253, in loseConnection
self.conn.sendClose(self)
File
"/usr/lib/python2.5/site-packages/Twisted-8.2.0-py2.5-linux-i686.egg/twisted/conch/ssh/connection.py",
line 491, in sendClose
self.channelsToRemoteChannel[channel]))
exceptions.KeyError:
<twisted.conch.ssh.forwarding.SSHListenClientForwardingChannel instance
at 0x972048c>
-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-
It works well in the other cases, i.e.:
* the errback is triggered but the tunnel is not used (comment line 57,
uncomment line 59)
* the errback is not triggered (start the XMLRPC server by uncommenting
line 100), using the tunnel or not
You get the error only when the tunnel is used AND the errback is triggered.
To run the example execute it with an user name that can login using ssh
on your host, e.g. 'python test.py someuser' and enter its password.
Cheers,
Luper
#!/usr/bin/env python
import sys
from getpass import getpass
from twisted.python import log
from twisted.conch.ssh import connection, transport, userauth, keys, \
forwarding, channel
from twisted.conch.ssh.common import NS
from twisted.internet import defer, protocol, reactor
from twisted.web import server, xmlrpc
from twisted.web.xmlrpc import Proxy
conn = None
def connect(user, host, port=22):
return reactor.connectTCP(host, port, Factory(user, Transport))
class Factory(protocol.ClientFactory):
def __init__(self, user, protocol):
self.user = user
self.protocol = protocol
def buildProtocol(self, addr):
p = self.protocol(self.user)
p.factory = self
return p
class Transport(transport.SSHClientTransport):
def __init__(self, user):
self.user = user
def verifyHostKey(self, pubkey, fingerprint):
return defer.succeed(1)
def connectionSecure(self):
self.requestService(UserAuth(self.user, Connection()))
class UserAuth(userauth.SSHUserAuthClient):
def getPassword(self, prompt=None):
return defer.succeed(getpass("password: "))
class Connection(connection.SSHConnection):
def __init__(self, *args, **kwargs):
connection.SSHConnection.__init__(self, *args, **kwargs)
self.forwarding_sockets = []
def serviceStarted(self):
# Create a tunnel from 12345 to 54321
self.forward_port(12345, 54321)
# Do something through the tunnel
p = Proxy('http://localhost:12345/') # passing through the tunnel,
# triggers the KeyError
#p = Proxy('http://localhost:54321/') # not using the tunnel, works
print "ping...",
d = p.callRemote("ping")
def stop_ok(response):
print response
conn.disconnect()
reactor.stop()
def stop_error(error):
print "error", error
conn.disconnect()
reactor.stop()
d.addCallback(stop_ok)
d.addErrback(stop_error)
def serviceStopped(self):
# Stop forwarding sockets
for socket in self.forwarding_sockets:
socket.stopListening()
def forward_port(self, local_port, remote_port):
print "forwarding %d => %d" % (local_port, remote_port)
socket = reactor.listenTCP(local_port,
forwarding.SSHListenForwardingFactory(self,
("localhost", remote_port),
forwarding.SSHListenClientForwardingChannel))
self.forwarding_sockets.append(socket)
class DummyServer(xmlrpc.XMLRPC):
def xmlrpc_ping(self):
return "pong"
if __name__ == "__main__":
if len(sys.argv) != 2:
print "usage: test.py user"
sys.exit(1)
#log.startLogging(sys.stdout)
# If the server is not running, stop_error() errback is triggered and we
# have the KeyError when passing through the tunnel
#reactor.listenTCP(54321, server.Site(DummyServer()))
conn = connect(sys.argv[1], "localhost")
reactor.run()
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