show_dhcp.py
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	#!/usr/bin/env python3
	#
	# Copyright (C) 2018-2020 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/>.
	#
	# TODO: merge with show_dhcpv6.py

	from json import dumps
	from argparse import ArgumentParser
	from ipaddress import ip_address
	from tabulate import tabulate
	from sys import exit
	from collections import OrderedDict
	from datetime import datetime

	from isc_dhcp_leases import Lease, IscDhcpLeases

	from vyos.config import Config
	from vyos.util import call


	lease_file = "/config/dhcpd.leases"
	pool_key = "shared-networkname"

	lease_display_fields = OrderedDict()
	lease_display_fields['ip'] = 'IP address'
	lease_display_fields['hardware_address'] = 'Hardware address'
	lease_display_fields['state'] = 'State'
	lease_display_fields['start'] = 'Lease start'
	lease_display_fields['end'] = 'Lease expiration'
	lease_display_fields['remaining'] = 'Remaining'
	lease_display_fields['pool'] = 'Pool'
	lease_display_fields['hostname'] = 'Hostname'

	lease_valid_states = ['all', 'active', 'free', 'expired', 'released', 'abandoned', 'reset', 'backup']

	def in_pool(lease, pool):
	if pool_key in lease.sets:
	if lease.sets[pool_key] == pool:
	return True

	return False

	def utc_to_local(utc_dt):
	return datetime.fromtimestamp((utc_dt - datetime(1970,1,1)).total_seconds())

	def get_lease_data(lease):
	data = {}

	# isc-dhcp lease times are in UTC so we need to convert them to local time to display
	try:
	data["start"] = utc_to_local(lease.start).strftime("%Y/%m/%d %H:%M:%S")
	except:
	data["start"] = ""

	try:
	data["end"] = utc_to_local(lease.end).strftime("%Y/%m/%d %H:%M:%S")
	except:
	data["end"] = ""

	try:
	data["remaining"] = lease.end - datetime.utcnow()
	# negative timedelta prints wrong so bypass it
	if (data["remaining"].days >= 0):
	# substraction gives us a timedelta object which can't be formatted with strftime
	# so we use str(), split gets rid of the microseconds
	data["remaining"] = str(data["remaining"]).split('.')[0]
	else:
	data["remaining"] = ""
	except:
	data["remaining"] = ""

	# currently not used but might come in handy
	# todo: parse into datetime string
	for prop in ['tstp', 'tsfp', 'atsfp', 'cltt']:
	if prop in lease.data:
	data[prop] = lease.data[prop]
	else:
	data[prop] = ''

	data["hardware_address"] = lease.ethernet
	data["hostname"] = lease.hostname

	data["state"] = lease.binding_state
	data["ip"] = lease.ip

	try:
	data["pool"] = lease.sets[pool_key]
	except:
	data["pool"] = ""

	return data

	def get_leases(config, leases, state, pool=None, sort='ip'):
	# get leases from file
	leases = IscDhcpLeases(lease_file).get()

	# filter leases by state
	if 'all' not in state:
	leases = list(filter(lambda x: x.binding_state in state, leases))

	# filter leases by pool name
	if pool is not None:
	if config.exists_effective("service dhcp-server shared-network-name {0}".format(pool)):
	leases = list(filter(lambda x: in_pool(x, pool), leases))
	else:
	print("Pool {0} does not exist.".format(pool))
	exit(0)

	# should maybe filter all state=active by lease.valid here?

	# sort by start time to dedupe (newest lease overrides older)
	leases = sorted(leases, key = lambda lease: lease.start)

	# dedupe by converting to dict
	leases_dict = {}
	for lease in leases:
	# dedupe by IP
	leases_dict[lease.ip] = lease

	# convert the lease data
	leases = list(map(get_lease_data, leases_dict.values()))

	# apply output/display sort
	if sort == 'ip':
	leases = sorted(leases, key = lambda lease: int(ip_address(lease['ip'])))
	else:
	leases = sorted(leases, key = lambda lease: lease[sort])

	return leases

	def show_leases(leases):
	lease_list = []
	for l in leases:
	lease_list_params = []
	for k in lease_display_fields.keys():
	lease_list_params.append(l[k])
	lease_list.append(lease_list_params)

	output = tabulate(lease_list, lease_display_fields.values())

	print(output)

	def get_pool_size(config, pool):
	size = 0
	subnets = config.list_effective_nodes("service dhcp-server shared-network-name {0} subnet".format(pool))
	for s in subnets:
	ranges = config.list_effective_nodes("service dhcp-server shared-network-name {0} subnet {1} range".format(pool, s))
	for r in ranges:
	start = config.return_effective_value("service dhcp-server shared-network-name {0} subnet {1} range {2} start".format(pool, s, r))
	stop = config.return_effective_value("service dhcp-server shared-network-name {0} subnet {1} range {2} stop".format(pool, s, r))

	size += int(ip_address(stop)) - int(ip_address(start))

	return size

	def show_pool_stats(stats):
	headers = ["Pool", "Size", "Leases", "Available", "Usage"]
	output = tabulate(stats, headers)

	print(output)

	if __name__ == '__main__':
	parser = ArgumentParser()

	group = parser.add_mutually_exclusive_group()
	group.add_argument("-l", "--leases", action="store_true", help="Show DHCP leases")
	group.add_argument("-s", "--statistics", action="store_true", help="Show DHCP statistics")
	group.add_argument("--allowed", type=str, choices=["pool", "sort", "state"], help="Show allowed values for argument")

	parser.add_argument("-p", "--pool", type=str, help="Show lease for specific pool")
	parser.add_argument("-S", "--sort", type=str, default='ip', help="Sort by")
	parser.add_argument("-t", "--state", type=str, nargs="+", default=["active"], help="Lease state to show (can specify multiple with spaces)")
	parser.add_argument("-j", "--json", action="store_true", default=False, help="Produce JSON output")

	args = parser.parse_args()

	conf = Config()

	if args.allowed == 'pool':
	if conf.exists_effective('service dhcp-server'):
	print(' '.join(conf.list_effective_nodes("service dhcp-server shared-network-name")))
	exit(0)
	elif args.allowed == 'sort':
	print(' '.join(lease_display_fields.keys()))
	exit(0)
	elif args.allowed == 'state':
	print(' '.join(lease_valid_states))
	exit(0)
	elif args.allowed:
	parser.print_help()
	exit(1)

	if args.sort not in lease_display_fields.keys():
	print(f'Invalid sort key, choose from: {list(lease_display_fields.keys())}')
	exit(0)

	if not set(args.state) < set(lease_valid_states):
	print(f'Invalid lease state, choose from: {lease_valid_states}')
	exit(0)

	# Do nothing if service is not configured
	if not conf.exists_effective('service dhcp-server'):
	print("DHCP service is not configured.")
	exit(0)

	# if dhcp server is down, inactive leases may still be shown as active, so warn the user.
	if call('systemctl -q is-active isc-dhcp-server.service') != 0:
	print("WARNING: DHCP server is configured but not started. Data may be stale.")

	if args.leases:
	leases = get_leases(conf, lease_file, args.state, args.pool, args.sort)

	if args.json:
	print(dumps(leases, indent=4))
	else:
	show_leases(leases)

	elif args.statistics:
	pools = []

	# Get relevant pools
	if args.pool:
	pools = [args.pool]
	else:
	pools = conf.list_effective_nodes("service dhcp-server shared-network-name")

	# Get pool usage stats
	stats = []
	for p in pools:
	size = get_pool_size(conf, p)
	leases = len(get_leases(conf, lease_file, state='active', pool=p))

	use_percentage = round(leases / size * 100) if size != 0 else 0

	if args.json:
	pool_stats = {"pool": p, "size": size, "leases": leases,
	"available": (size - leases), "percentage": use_percentage}
	else:
	# For tabulate
	pool_stats = [p, size, leases, size - leases, "{0}%".format(use_percentage)]
	stats.append(pool_stats)

	# Print stats
	if args.json:
	print(dumps(stats, indent=4))
	else:
	show_pool_stats(stats)

	else:
	parser.print_help()
	exit(1)

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