Current File : //backups/router/usr/local/opnsense/site-python/watchers/dhcpd.py
"""
Copyright (c) 2016-2019 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.
"""
import os
import calendar
import datetime
class DHCPDLease(object):
def __init__(self, watch_file='/var/dhcpd/var/db/dhcpd.leases'):
""" init watcher
:param watch_file: filename to watch
:return: watcher object
"""
self.watch_file = watch_file
self._section_data = []
self._fhandle = None
self._last_pos = None
def _open(self):
""" (re)open watched file
:return: None
"""
try:
self._fhandle = open(self.watch_file, 'r')
self._last_pos = None
self._section_data = []
except IOError:
self._fhandle = None
@staticmethod
def parse_lease(lines):
""" parse dhcp lease
:param lines: lease section as list item
:return: dictionary
"""
hostname_override = None
lease = dict()
lease['address'] = lines[0].split()[1]
for line in lines:
parts = line.split()
field_name = parts[0]
field_value = None
if field_name in ('starts', 'ends', 'tstp', 'tsfp', 'atsfp', 'cltt') and len(parts) >= 3:
dt = '%s %s' % (parts[2], parts[3])
try:
field_value = calendar.timegm(datetime.datetime.strptime(dt, "%Y/%m/%d %H:%M:%S;").timetuple())
except ValueError:
field_value = None
elif field_name == 'hardware' and len(parts) >= 3:
field_value = {'hardware-type': parts[1], 'mac-address': parts[2].split(';')[0]}
elif field_name in('uid', 'client-hostname') and len(parts) >= 2 and parts[1].find('"') > -1:
field_value = parts[1].split('"')[1]
elif field_name == 'set' and len(parts) >= 4 and parts[1] == 'hostname-override' and parts[3].find('"') > -1:
hostname_override = parts[3].split('"')[1]
elif field_name == 'binding' and len(parts) >= 3 and parts[1] == 'state':
field_value = parts[2].strip(';')
if field_value is not None:
lease[field_name] = field_value
if hostname_override is not None:
lease['client-hostname'] = hostname_override
return lease
def watch(self):
""" watch file, return lease dictionaries
:return: iterator for leases
"""
if self._fhandle is None:
# nothing to watch, try to (re)open return when failed
self._open()
elif os.fstat(self._fhandle.fileno()).st_ino != os.stat(self.watch_file).st_ino:
# file rotation, inode changed
self._open()
elif self._last_pos is not None:
self._fhandle.seek(self._last_pos)
if self._fhandle is not None:
while True:
line = self._fhandle.readline()
if line:
if len(line) > 5 and line[0:5] == 'lease':
self._section_data.append(line)
elif len(line) > 1 and line[0] == '}' and len(self._section_data) > 0:
self._section_data.append(line)
yield self.parse_lease(self._section_data)
self._section_data = []
elif len(self._section_data) > 0:
self._section_data.append(line)
else:
break
self._last_pos = self._fhandle.tell()
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