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# Copyright (C) 2012 Yipit, Inc <coders@yipit.com>
#
# This file is part of paramiko.
#
# Paramiko is free software; you can redistribute it and/or modify it under the
# terms of the GNU Lesser General Public License as published by the Free
# Software Foundation; either version 2.1 of the License, or (at your option)
# any later version.
#
# Paramiko is distrubuted in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
# A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with Paramiko; if not, write to the Free Software Foundation, Inc.,
# 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
"""
L{ProxyCommand}.
"""
import os
from shlex import split as shlsplit
import signal
from subprocess import Popen, PIPE
from paramiko.ssh_exception import ProxyCommandFailure
class ProxyCommand(object):
"""
Wraps a subprocess running ProxyCommand-driven programs.
This class implements a the socket-like interface needed by the
L{Transport} and L{Packetizer} classes. Using this class instead of a
regular socket makes it possible to talk with a Popen'd command that will
proxy traffic between the client and a server hosted in another machine.
"""
def __init__(self, command_line):
"""
Create a new CommandProxy instance. The instance created by this
class can be passed as an argument to the L{Transport} class.
@param command_line: the command that should be executed and
used as the proxy.
@type command_line: str
"""
self.cmd = shlsplit(command_line)
self.process = Popen(self.cmd, stdin=PIPE, stdout=PIPE, stderr=PIPE)
def send(self, content):
"""
Write the content received from the SSH client to the standard
input of the forked command.
@param content: string to be sent to the forked command
@type content: str
"""
try:
self.process.stdin.write(content)
except IOError, e:
# There was a problem with the child process. It probably
# died and we can't proceed. The best option here is to
# raise an exception informing the user that the informed
# ProxyCommand is not working.
raise BadProxyCommand(' '.join(self.cmd), e.strerror)
return len(content)
def recv(self, size):
"""
Read from the standard output of the forked program.
@param size: how many chars should be read
@type size: int
@return: the length of the read content
@rtype: int
"""
try:
return os.read(self.process.stdout.fileno(), size)
except IOError, e:
raise BadProxyCommand(' '.join(self.cmd), e.strerror)
def close(self):
os.kill(self.process.pid, signal.SIGTERM)
def settimeout(self, timeout):
# Timeouts are meaningless for this implementation, but are part of the
# spec, so must be present.
pass
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