#!/usr/bin/env python3
#
# Copyright (C) 2019 VyOS maintainers and contributors
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 or later as
# published by the Free Software Foundation.
#
# 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/>.
#

# This migration script will check if there is a allow-from directive configured
# for the dns forwarding service - if not, the node will be created with the old
# default values of 0.0.0.0/0 and ::/0

import sys
from vyos.configtree import ConfigTree

if (len(sys.argv) < 1):
    print("Must specify file name!")
    sys.exit(1)

file_name = sys.argv[1]

with open(file_name, 'r') as f:
    config_file = f.read()

config = ConfigTree(config_file)

base = ['service', 'dns', 'forwarding']
if not config.exists(base):
    # Nothing to do
    sys.exit(0)
else:
    if not config.exists(base + ['allow-from']):
        config.set(base + ['allow-from'], value='0.0.0.0/0', replace=False)
        config.set(base + ['allow-from'], value='::/0', replace=False)

    try:
        with open(file_name, 'w') as f:
            f.write(config.to_string())
    except OSError as e:
        print("Failed to save the modified config: {}".format(e))
        sys.exit(1)