# Copyright(C) 2005 INL
# Written by Jean Gillaux <jean@inl.fr>
#
# 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, version 3 of the License.
#
#  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/>.
# classes for iptables NAT rules

from os import linesep
import re

def gen_rule(*args):
    text = " ".join(args)
    # Remove trailing spaces
    text = re.sub(" +%s$" % linesep, linesep, text)
    return text

def gen_rule_list(arg_list):
    return gen_rule(*arg_list)

_TARGET_NAMES = {
    'accept': 'ACCEPT',
    'reject': 'REJECT',
}

def make_target(s):
    return _TARGET_NAMES.get(s, 'DROP')

def _make_syn(target,h):
    """returns chain that fits well to the target of the iptables command
        example: for accept target: we want to match syn packets, the others are matched by the
        RELATED/ESTABLISHED rules
    """
    res = ''
    if target == 'ACCEPT':
        res += '-m state --state NEW'
        if h.get('proto') == 'tcp':
            res += ' --syn'
    return res