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import os
import socket
import subprocess as ssubprocess
from sshuttle.helpers import log, debug1, Fatal, family_to_string
def nonfatal(func, *args):
try:
func(*args)
except Fatal as e:
log('error: %s\n' % e)
def ipt_chain_exists(family, table, name):
if family == socket.AF_INET6:
cmd = 'ip6tables'
elif family == socket.AF_INET:
cmd = 'iptables'
else:
raise Exception('Unsupported family "%s"' % family_to_string(family))
argv = [cmd, '-t', table, '-nL']
env = {
'PATH': os.environ['PATH'],
'LC_ALL': "C",
}
try:
output = ssubprocess.check_output(argv, env=env)
for line in output.decode('ASCII').split('\n'):
if line.startswith('Chain %s ' % name):
return True
except ssubprocess.CalledProcessError as e:
raise Fatal('%r returned %d' % (argv, e.returncode))
def ipt(family, table, *args):
if family == socket.AF_INET6:
argv = ['ip6tables', '-t', table] + list(args)
elif family == socket.AF_INET:
argv = ['iptables', '-t', table] + list(args)
else:
raise Exception('Unsupported family "%s"' % family_to_string(family))
debug1('>> %s\n' % ' '.join(argv))
env = {
'PATH': os.environ['PATH'],
'LC_ALL': "C",
}
rv = ssubprocess.call(argv, env=env)
if rv:
raise Fatal('%r returned %d' % (argv, rv))
def nft(family, table, action, *args):
if family in (socket.AF_INET, socket.AF_INET6):
argv = ['nft', action, 'inet', table] + list(args)
else:
raise Exception('Unsupported family "%s"' % family_to_string(family))
debug1('>> %s\n' % ' '.join(argv))
env = {
'PATH': os.environ['PATH'],
'LC_ALL': "C",
}
rv = ssubprocess.call(argv, env=env)
if rv:
raise Fatal('%r returned %d' % (argv, rv))
_no_ttl_module = False
def ipt_ttl(family, *args):
global _no_ttl_module
if not _no_ttl_module:
# we avoid infinite loops by generating server-side connections
# with ttl 42. This makes the client side not recapture those
# connections, in case client == server.
try:
argsplus = list(args) + ['-m', 'ttl', '!', '--ttl', '42']
ipt(family, *argsplus)
except Fatal:
ipt(family, *args)
# we only get here if the non-ttl attempt succeeds
log('sshuttle: warning: your iptables is missing '
'the ttl module.\n')
_no_ttl_module = True
else:
ipt(family, *args)
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