Current File : //backups/router/usr/local/opnsense/scripts/dhcp/dnsmasq_watcher.py
#!/usr/local/bin/python3
"""
Copyright (c) 2016-2020 Ad Schellevis <ad@opnsense.org>
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
1. Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
--------------------------------------------------------------------------------------
watch dhcp lease file and build include file for dnsmasq
"""
import ipaddress
import os
import sys
import time
import argparse
import syslog
import signal
import re
from configparser import ConfigParser
sys.path.insert(0, "/usr/local/opnsense/site-python")
from daemonize import Daemonize
import watchers.dhcpd
def run_watcher(target_filename, default_domain, watch_file, service_pid):
# cleanup interval (seconds)
cleanup_interval = 60
# initiate lease watcher and setup cache
dhcpdleases = watchers.dhcpd.DHCPDLease(watch_file)
cached_leases = dict()
hostname_pattern = re.compile("(?!-)[A-Z0-9-_]*(?<!-)$", re.IGNORECASE)
# start watching dhcp leases
last_cleanup = time.time()
while True:
for lease in dhcpdleases.watch():
if 'ends' in lease and lease['ends'] > time.time() \
and 'client-hostname' in lease and 'address' in lease and lease['client-hostname']:
if all(hostname_pattern.match(part) for part in lease['client-hostname'].strip('.').split('.')):
address = ipaddress.ip_address(lease['address'])
lease['domain'] = default_domain
cached_leases[lease['address']] = lease
dhcpd_changed = True
else:
syslog.syslog(
syslog.LOG_WARNING,
"dhcpd leases: %s not a valid hostname, ignoring" % lease['client-hostname']
)
if time.time() - last_cleanup > cleanup_interval:
# cleanup every x seconds
last_cleanup = time.time()
addresses = list(cached_leases)
for address in addresses:
if cached_leases[address]['ends'] < time.time():
syslog.syslog(
syslog.LOG_NOTICE,
"dhcpd expired %s @ %s" % (cached_leases[address]['client-hostname'], address)
)
del cached_leases[address]
dhcpd_changed = True
if dhcpd_changed:
with open(target_filename, 'w') as dnsmasq_conf:
dnsmasq_conf.write('# dynamic entries from dhcpd.leases automatically entered\n')
for address in cached_leases:
dnsmasq_conf.write('%s %s.%s %s\n' % (
address,
cached_leases[address]['client-hostname'],
cached_leases[address]['domain'],
cached_leases[address]['client-hostname']
))
pid = int(open(service_pid).read())
os.kill(pid, signal.SIGHUP)
dhcpd_changed = False
# wait for next cycle
time.sleep(1)
if __name__ == '__main__':
parser = argparse.ArgumentParser()
parser.add_argument('--domain', help='default domain to use', default='local')
parser.add_argument('--foreground', help='run in foreground', default=False, action='store_true')
parser.add_argument('--pid', help='pid file location', default='/var/run/dnsmasq_dhcpd.pid')
parser.add_argument('--servicepid', help='dnsmasq pid file location', default='/var/run/dnsmasq.pid')
parser.add_argument('--source', help='source leases file', default='/var/dhcpd/var/db/dhcpd.leases')
parser.add_argument('--target', help='target config file', default='/var/etc/dnsmasq-leases')
inputargs = parser.parse_args()
syslog.openlog('dnsmasq', facility=syslog.LOG_LOCAL4)
if inputargs.foreground:
run_watcher(
target_filename=inputargs.target,
default_domain=inputargs.domain,
watch_file=inputargs.source,
service_pid=inputargs.servicepid
)
else:
syslog.syslog(syslog.LOG_NOTICE, 'daemonize dnsmasq dhcpd watcher.')
cmd = lambda : run_watcher(
target_filename=inputargs.target,
default_domain=inputargs.domain,
watch_file=inputargs.source,
service_pid=inputargs.servicepid
)
daemon = Daemonize(app="dnsmasq_dhcpd", pid=inputargs.pid, action=cmd)
daemon.start()
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