forked from hswaw/hscloud
235 lines
7.8 KiB
Python
235 lines
7.8 KiB
Python
import threading
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import os
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import io
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import logging
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from typing import Tuple, List, Optional, NamedTuple
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from time import sleep, time, mktime
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from datetime import datetime, timezone
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logger = logging.getLogger(__name__)
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def strfts(ts, format='%d/%m/%Y %H:%M'):
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return datetime.fromtimestamp(ts).strftime(format)
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class DhcpLease(NamedTuple):
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hwaddr: Optional[str]
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atime: Optional[float]
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ip: Optional[str]
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name: Optional[str]
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class ActiveDevices:
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def __init__(self):
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self._devices = {}
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def purge_stale(self, timeout):
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now = time()
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for device in list(self._devices.values()):
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if now - device.atime > timeout:
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del self._devices[device.hwaddr]
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def add(self, lease: DhcpLease) -> bool:
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if lease.atime is None:
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lease = lease._replace(atime=time())
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if lease.hwaddr not in self._devices or self._devices[lease.hwaddr].atime < lease.atime:
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self._devices[lease.hwaddr] = lease
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return True
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return False
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def update(self, devices) -> List[str]:
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'''Add entries from another ActiveDevices instance
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Args:
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devices: list of entries to be added
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Returns: list of updated enties
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'''
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updated = []
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for device in devices._devices.values():
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if self.add(device):
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updated.append(device)
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return updated
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class Updater(threading.Thread):
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def __init__(self, timeout, logger=logger, *a, **kw):
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self.timeout = timeout
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self.lock = threading.Lock()
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self.logger = logger
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self.active = ActiveDevices()
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threading.Thread.__init__(self, *a, **kw)
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self.daemon = True
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def get_active_devices(self):
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with self.lock:
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self.active.purge_stale(self.timeout)
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return dict(self.active._devices)
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def get_device(self, ip):
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with self.lock:
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active_devices = iter(self.get_active_devices().values())
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for device in active_devices:
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if device.ip == ip:
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return device.hwaddr, device.name
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return None, None
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def update(self, devices: ActiveDevices):
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for device in devices._devices.values():
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with self.lock:
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changed = self.active.add(device)
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if changed:
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self.logger.info('updated %s with atime %s and ip %s',
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device.hwaddr, strfts(device.atime), device.ip)
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#class CapUpdater(Updater):
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# def __init__(self, cap_file, *a, **kw):
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# self.cap_file = cap_file
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# Updater.__init__(self, *a, **kw)
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#
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# def run(self):
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# while True:
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# try:
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# with open(self.cap_file, 'r', buffering=0) as f:
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# self.logger.info('Updater ready on cap file %s',
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# self.cap_file)
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# lines = [l.strip() for l in f.read().split('\n')]
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# for hwaddr in lines:
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# if hwaddr:
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# self.update(hwaddr)
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# self.logger.warning('Cap file %s closed, reopening',
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# self.cap_file)
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# except Exception as e:
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# self.logger.error('Updater got an exception:\n' +
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# traceback.format_exc(e))
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# sleep(10.0)
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class MtimeUpdater(Updater):
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def __init__(self, lease_file, *a, **kw):
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self.lease_file = lease_file
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self.position = 0
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self.last_modified = 0
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Updater.__init__(self, *a, **kw)
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def file_changed(self, f):
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"""Callback on changed lease file
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Args:
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f: Lease file. File offset can be used to skip already parsed lines.
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Returns: New byte offset pointing after last parsed byte.
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"""
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return f.tell()
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def _trigger_update(self):
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self.logger.info('Lease file changed, updating')
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with open(self.lease_file, 'r') as f:
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f.seek(self.position)
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self.position = self.file_changed(f)
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def run(self):
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"""Periodicaly check if file has changed
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From ISC DHCPD manual:
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New leases are appended to the end of the dhcpd.leases file. In
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order to prevent the file from becoming arbitrarily large, from
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time to time dhcpd creates a new dhcpd.leases file from its in-core
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lease database. Once this file has been written to disk, the old
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file is renamed dhcpd.leases~, and the new file is renamed
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dhcpd.leases.
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"""
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while True:
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try:
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stat = os.stat(self.lease_file)
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mtime = stat.st_mtime
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size = stat.st_size
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if size < self.position:
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self.logger.info('leases file changed - reseting pointer')
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self.position = 0
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try:
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# checking if DHCPD performed cleanup
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# cleanup during operation seems to be currently broken
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# on customs so this could never execute
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purge_time = os.stat(self.lease_file + '~').st_mtime
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if purge_time > self.last_modified:
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self.logger.info('leases file purged - reseting pointer')
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self.position = 0
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except FileNotFoundError:
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pass
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if mtime > self.last_modified:
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self._trigger_update()
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self.last_modified = mtime
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sleep(5.0)
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except Exception:
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self.logger.exception('Exception in updater')
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sleep(10.0)
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class DnsmasqUpdater(MtimeUpdater):
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def file_changed(self, f):
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raise NotImplementedError(
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"This was not tested after adding differential update")
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for line in f:
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ts, hwaddr, ip, name, client_id = line.split(' ')
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self.update(hwaddr, int(ts), ip, name)
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return f.tell()
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def parse_isc_dhcpd_leases(leases_file: io.TextIOBase) -> Tuple[int, ActiveDevices]:
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"""Parse ISC dhcpd server leases file
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Args:
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leases_file: opened leases file. To skip already parsed part use seek
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before calling.
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Returns: Byte offset (as returned by tell()) of last parsed entry and
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dictionary of parsed leases
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"""
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leases = ActiveDevices()
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ip: Optional[str] = None
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hwaddr: Optional[str] = None
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atime: Optional[float] = None
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name: Optional[str] = None
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lease = False
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offset = leases_file.tell()
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while True:
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# using readline because iter(file) blocks file.tell usage
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line = leases_file.readline()
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if not line:
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return offset, leases
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line = line.split('#')[0]
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cmd = line.strip().split()
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if not cmd:
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continue
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if lease:
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field = cmd[0]
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if(field == 'starts'):
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dt = datetime.strptime(' '.join(cmd[2:]),
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'%Y/%m/%d %H:%M:%S;')
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atime = dt.replace(tzinfo=timezone.utc).timestamp()
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if(field == 'client-hostname'):
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name = cmd[1][1:-2]
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if(field == 'hardware'):
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hwaddr = cmd[2][:-1]
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if(field.startswith('}')):
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offset = leases_file.tell()
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lease = False
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if hwaddr is not None and atime is not None:
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leases.add(DhcpLease(hwaddr, atime, ip, name))
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hwaddr, atime = None, None
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elif cmd[0] == 'lease':
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ip = cmd[1]
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hwaddr, atime, name = None, None, None
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lease = True
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class DhcpdUpdater(MtimeUpdater):
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def file_changed(self, f):
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offset, devices = parse_isc_dhcpd_leases(f)
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self.update(devices)
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return offset
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