blob: f97873b1b23ee1346362a1107888009681f912db [file] [log] [blame]
# Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
import logging, os
from autotest_lib.client.common_lib import error, utils
# Flag file used to tell backchannel script it's okay to run.
BACKCHANNEL_FILE = '/mnt/stateful_partition/etc/enable_backchannel_network'
class Backchannel(object):
"""Wrap backchannel in a context manager so it can be used with with.
Example usage:
with backchannel.Backchannel():
The backchannel will be torn down whether or not 'block' throws.
def __init__(self, *args, **kwargs):
self.args = args
self.kwargs = kwargs
self.interface = None
def __enter__(self):
self.setup(*self.args, **self.kwargs)
return self
def __exit__(self, exception, value, traceback):
return False
def setup(self, create_ssh_routes=True):
"""Enables the backchannel interface.
create_ssh_routes: If true set up routes so that all
existing SSH sessions will remain open.
True if the backchannel is already set up, or was
set up by this call, otherwise False.
# If the backchannel interface is already up there's nothing
# for us to do.
if is_network_iface_running('eth_test'):
return True
# Retrieve the gateway for the default route.
line = utils.system_output(
"route -n | awk '/^ { print $2, $8 }'").split('\n')[0]
gateway, self.interface = line.strip().split(' ')
# Retrieve list of open ssh sessions so we can reopen
# routes afterward.
if create_ssh_routes:
out = utils.system_output(
"netstat -tanp | grep :22 | "
"grep ESTABLISHED | awk '{print $5}'")
# Extract IP from IP:PORT listing. Uses set to remove
# duplicates.
open_ssh = list(set(item.strip().split(':')[0] for item in
out.split('\n') if item.strip()))
backchannel('setup %s' % self.interface)
# Create routes so existing SSH sessions will stay open.
if create_ssh_routes:
for ip in open_ssh:
# Add route using the pre-backchannel gateway.
backchannel('reach %s %s' % (ip, gateway))
except Exception, e:
return False
# Remove backchannel file flag so system reverts to normal
# on reboot.
if os.path.isfile(BACKCHANNEL_FILE):
return True
def teardown(self):
if self.interface:
backchannel('teardown %s' % self.interface)
def backchannel(args):
utils.system('/usr/local/lib/flimflam/test/backchannel %s' % args)
def is_network_iface_running(name):
out = utils.system_output('ifconfig %s' % name)
except error.CmdError, e:
return False
return out.find('RUNNING') >= 0