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# -*- coding: utf-8 -*-
#
# python-netfilter - Python modules for manipulating netfilter rules
# Copyright (C) 2007-2012 Bolloré Telecom
# Copyright (C) 2013-2016 Jeremy Lainé
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
import os
import re
import subprocess
import netfilter.parser
class IptablesError(Exception):
def __init__(self, command, message):
self.command = command
self.message = message
def __str__(self):
return "command: %s\nmessage: %s" % (self.command, self.message)
class Table:
"""The Table class represents a netfilter table (IPv4 or IPv6).
"""
__iptables_wait_option = None
def __init__(self, name, auto_commit = True, ipv6 = False):
"""Constructs a new netfilter Table.
If auto_commit is true, commands are executed immediately,
otherwise they are buffered and you need to call the commit()
method to execute them.
If ipv6 is true then ip6tables and ip6tables-save are used
instead of iptables and iptables-save.
"""
self.auto_commit = auto_commit
self.__name = name
self.__buffer = []
if ipv6:
self.__iptables = 'ip6tables'
self.__iptables_save = 'ip6tables-save'
else:
self.__iptables = 'iptables'
self.__iptables_save = 'iptables-save'
def create_chain(self, chainname):
"""Creates the specified user-defined chain.
"""
self.__run_iptables(['-N', chainname])
def delete_chain(self, chainname=None):
"""Attempts to delete the specified user-defined chain (all the
chains in the table if none is given).
"""
args = ['-X']
if chainname: args.append(chainname)
self.__run_iptables(args)
def flush_chain(self, chainname=None):
"""Flushes the specified chain (all the chains in the table if
none is given). This is equivalent to deleting all the rules
one by one.
"""
args = ['-F']
if chainname: args.append(chainname)
self.__run_iptables(args)
def list_chains(self):
"""Returns a list of strings representing the chains in the
Table.
"""
return self.__get_chains().keys()
def rename_chain(self, old_chain_name, new_chain_name):
"""Renames the specified user-defined chain.
"""
self.__run_iptables(['-E', old_chain_name, new_chain_name])
def get_policy(self, chainname):
"""Gets the policy for the specified built-in chain.
"""
return self.__get_chains()[chainname]['policy']
def set_policy(self, chainname, policy):
"""Sets the policy for the specified built-in chain.
"""
self.__run_iptables(['-P', chainname, policy])
def append_rule(self, chainname, rule):
"""Appends a Rule to the specified chain.
"""
self.__run_iptables(['-A', chainname] + rule.specbits())
def delete_rule(self, chainname, rule):
"""Deletes a Rule from the specified chain.
"""
self.__run_iptables(['-D', chainname] + rule.specbits())
def prepend_rule(self, chainname, rule):
"""Prepends a Rule to the specified chain.
"""
self.__run_iptables(['-I', chainname, '1'] + rule.specbits())
def list_rules(self, chainname):
"""Returns a list of Rules in the specified chain.
"""
data = self.__run([self.__iptables_save, '-t', self.__name, '-c'])
return netfilter.parser.parse_rules(data, chainname)
def commit(self):
"""Commits any buffered commands. This is only useful if
auto_commit is False.
"""
while len(self.__buffer) > 0:
self.__run(self.__buffer.pop(0))
def get_buffer(self):
"""Returns the command buffer. This is only useful if
auto_commit is False.
"""
return self.__buffer
def __get_chains(self):
data = self.__run([self.__iptables_save, '-t', self.__name, '-c'])
return netfilter.parser.parse_chains(data)
def __run_iptables(self, args):
if Table.__iptables_wait_option is None:
# check whether iptables supports --wait
try:
self.__run([self.__iptables, '-L', '-n', '--wait'])
Table.__iptables_wait_option = ['--wait']
except:
Table.__iptables_wait_option = []
cmd = [self.__iptables] + Table.__iptables_wait_option + ['-t', self.__name] + args
if self.auto_commit:
self.__run(cmd)
else:
self.__buffer.append(cmd)
def __run(self, cmd):
p = subprocess.Popen(cmd,
stdout=subprocess.PIPE,
stderr=subprocess.PIPE,
close_fds=True)
out, err = p.communicate()
out = out.decode('utf8')
err = err.decode('utf8')
status = p.wait()
# check exit status
if not os.WIFEXITED(status) or os.WEXITSTATUS(status):
if not re.match(r'(iptables|ip6tables): Chain already exists', err):
raise IptablesError(cmd, err)
return out
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