dhcpv6_server.py
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dhcpv6_server.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/>.

	import os

	from ipaddress import ip_address
	from ipaddress import ip_network
	from sys import exit

	from vyos.config import Config
	from vyos.template import render
	from vyos.template import is_ipv6
	from vyos.util import call
	from vyos.util import dict_search
	from vyos.validate import is_subnet_connected
	from vyos import ConfigError
	from vyos import airbag
	airbag.enable()

	config_file = '/run/dhcp-server/dhcpdv6.conf'

	def get_config(config=None):
	if config:
	conf = config
	else:
	conf = Config()
	base = ['service', 'dhcpv6-server']
	if not conf.exists(base):
	return None

	dhcpv6 = conf.get_config_dict(base, key_mangling=('-', '_'), get_first_key=True)
	return dhcpv6

	def verify(dhcpv6):
	# bail out early - looks like removal from running config
	if not dhcpv6 or 'disable' in dhcpv6:
	return None

	# If DHCP is enabled we need one share-network
	if 'shared_network_name' not in dhcpv6:
	raise ConfigError('No DHCPv6 shared networks configured. At least\n' \
	'one DHCPv6 shared network must be configured.')

	# Inspect shared-network/subnet
	subnets = []
	listen_ok = False
	for network, network_config in dhcpv6['shared_network_name'].items():
	# A shared-network requires a subnet definition
	if 'subnet' not in network_config:
	raise ConfigError(f'No DHCPv6 lease subnets configured for "{network}". At least one\n' \
	'lease subnet must be configured for each shared network!')

	for subnet, subnet_config in network_config['subnet'].items():
	if 'address_range' in subnet_config:
	if 'start' in subnet_config['address_range']:
	range6_start = []
	range6_stop = []
	for start, start_config in subnet_config['address_range']['start'].items():
	if 'stop' not in start_config:
	raise ConfigError(f'address-range stop address for start "{start}" is not defined!')
	stop = start_config['stop']

	# Start address must be inside network
	if not ip_address(start) in ip_network(subnet):
	raise ConfigError(f'address-range start address "{start}" is not in subnet "{subnet}"!')

	# Stop address must be inside network
	if not ip_address(stop) in ip_network(subnet):
	raise ConfigError(f'address-range stop address "{stop}" is not in subnet "{subnet}"!')

	# Stop address must be greater or equal to start address
	if not ip_address(stop) >= ip_address(start):
	raise ConfigError(f'address-range stop address "{stop}" must be greater or equal\n' \
	f'to the range start address "{start}"!')

	# DHCPv6 range start address must be unique - two ranges can't
	# start with the same address - makes no sense
	if start in range6_start:
	raise ConfigError(f'Conflicting DHCPv6 lease range:\n' \
	f'Pool start address "{start}" defined multipe times!')
	range6_start.append(start)

	# DHCPv6 range stop address must be unique - two ranges can't
	# end with the same address - makes no sense
	if stop in range6_stop:
	raise ConfigError(f'Conflicting DHCPv6 lease range:\n' \
	f'Pool stop address "{stop}" defined multipe times!')
	range6_stop.append(stop)

	if 'prefix' in subnet_config:
	for prefix in subnet_config['prefix']:
	if ip_network(prefix) not in ip_network(subnet):
	raise ConfigError(f'address-range prefix "{prefix}" is not in subnet "{subnet}""')

	# Prefix delegation sanity checks
	if 'prefix_delegation' in subnet_config:
	if 'start' not in subnet_config['prefix_delegation']:
	raise ConfigError('prefix-delegation start address not defined!')

	for prefix, prefix_config in subnet_config['prefix_delegation']['start'].items():
	if 'stop' not in prefix_config:
	raise ConfigError(f'Stop address of delegated IPv6 prefix range "{prefix}"\n'
	f'must be configured')

	if 'prefix_length' not in prefix_config:
	raise ConfigError('Length of delegated IPv6 prefix must be configured')

	# Static mappings don't require anything (but check if IP is in subnet if it's set)
	if 'static_mapping' in subnet_config:
	for mapping, mapping_config in subnet_config['static_mapping'].items():
	if 'ipv6_address' in mapping_config:
	# Static address must be in subnet
	if ip_address(mapping_config['ipv6_address']) not in ip_network(subnet):
	raise ConfigError(f'static-mapping address for mapping "{mapping}" is not in subnet "{subnet}"!')

	# Subnets must be unique
	if subnet in subnets:
	raise ConfigError(f'DHCPv6 subnets must be unique! Subnet {subnet} defined multiple times!')
	subnets.append(subnet)

	# DHCPv6 requires at least one configured address range or one static mapping
	# (FIXME: is not actually checked right now?)

	# There must be one subnet connected to a listen interface if network is not disabled.
	if 'disable' not in network_config:
	if is_subnet_connected(subnet):
	listen_ok = True

	# DHCPv6 subnet must not overlap. ISC DHCP also complains about overlapping
	# subnets: "Warning: subnet 2001:db8::/32 overlaps subnet 2001:db8:1::/32"
	net = ip_network(subnet)
	for n in subnets:
	net2 = ip_network(n)
	if (net != net2):
	if net.overlaps(net2):
	raise ConfigError('DHCPv6 conflicting subnet ranges: {0} overlaps {1}'.format(net, net2))

	if not listen_ok:
	raise ConfigError('None of the DHCPv6 subnets are connected to a subnet6 on\n' \
	'this machine. At least one subnet6 must be connected such that\n' \
	'DHCPv6 listens on an interface!')


	return None

	def generate(dhcpv6):
	# bail out early - looks like removal from running config
	if not dhcpv6 or 'disable' in dhcpv6:
	return None

	render(config_file, 'dhcp-server/dhcpdv6.conf.tmpl', dhcpv6)
	return None

	def apply(dhcpv6):
	# bail out early - looks like removal from running config
	if not dhcpv6 or 'disable' in dhcpv6:
	# DHCP server is removed in the commit
	call('systemctl stop isc-dhcp-server6.service')
	if os.path.exists(config_file):
	os.unlink(config_file)

	return None

	call('systemctl restart isc-dhcp-server6.service')
	return None

	if __name__ == '__main__':
	try:
	c = get_config()
	verify(c)
	generate(c)
	apply(c)
	except ConfigError as e:
	print(e)
	exit(1)

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