#!/bin/bash
#
# Copyright (C) 2021 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/>.

if [ "$reason" == "REBOOT" ] || [ "$reason" == "EXPIRE" ]; then
    return 0
fi

DHCP_HOOK_IFLIST="/tmp/ipsec_dhcp_waiting"

if [ -f $DHCP_HOOK_IFLIST ] && [ "$reason" == "BOUND" ]; then
    if grep -qw $interface $DHCP_HOOK_IFLIST; then
        sudo rm $DHCP_HOOK_IFLIST
        sudo /usr/libexec/vyos/conf_mode/vpn_ipsec.py
        return 0
    fi
fi

if [ "$old_ip_address" == "$new_ip_address" ] && [ "$reason" == "BOUND" ]; then
    return 0
fi

python3 - <<PYEND
import os
import re

from vyos.utils.process import call
from vyos.utils.process import cmd
from vyos.utils.file import read_file
from vyos.utils.file import write_file

SWANCTL_CONF="/etc/swanctl/swanctl.conf"

def ipsec_down(ip_address):
    # This prevents the need to restart ipsec and kill all active connections, only the stale connection is closed
    status = cmd('sudo ipsec statusall')
    connection_name = None
    for line in status.split("\n"):
        if line.find(ip_address) > 0:
            regex_match = re.search(r'(peer_[^:\[]+)', line)
            if regex_match:
                connection_name = regex_match[1]
                break
    if connection_name:
        call(f'sudo ipsec down {connection_name}')

if __name__ == '__main__':
    interface = os.getenv('interface')
    new_ip = os.getenv('new_ip_address')
    old_ip = os.getenv('old_ip_address')

    if os.path.exists(SWANCTL_CONF):
        conf_lines = read_file(SWANCTL_CONF)
        found = False
        to_match = f'# dhcp:{interface}'

        for i, line in enumerate(conf_lines):
            if line.find(to_match) > 0:
                conf_lines[i] = line.replace(old_ip, new_ip)
                found = True

        if found:
            write_file(SWANCTL_CONF, conf_lines)
            ipsec_down(old_ip)
            call('sudo ipsec rereadall')
            call('sudo ipsec reload')
            call('sudo swanctl -q')

    exit(0)
PYEND