dhcpv6_server.py
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dhcpv6_server.py
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	#!/usr/bin/env python3
	#
	# Copyright (C) 2018 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 sys
	import os
	import ipaddress

	import jinja2

	import vyos.validate

	from vyos.config import Config
	from vyos import ConfigError

	config_file = r'/etc/dhcp/dhcpdv6.conf'
	lease_file = r'/config/dhcpdv6.leases'
	daemon_config_file = r'/etc/default/isc-dhcpv6-server'

	# Please be careful if you edit the template.
	config_tmpl = """
	### Autogenerated by dhcpv6_server.py ###

	# For options please consult the following website:
	# https://www.isc.org/wp-content/uploads/2017/08/dhcp43options.html

	log-facility local7;
	{%- if preference %}
	option dhcp6.preference {{ preference }};
	{%- endif %}

	# Shared network configration(s)
	{% for network in shared_network %}
	{%- if not network.disabled -%}
	shared-network {{ network.name }} {
	{%- for subnet in network.subnet %}
	subnet6 {{ subnet.network }} {
	{%- for range in subnet.range6_prefix %}
	range6 {{ range.prefix }}{{ " temporary" if range.temporary }};
	{%- endfor %}
	{%- for range in subnet.range6 %}
	range6 {{ range.start }} {{ range.stop }};
	{%- endfor %}
	{%- if subnet.domain_search %}
	option dhcp6.domain-search {{ subnet.domain_search \| join(', ') }};
	{%- endif %}
	{%- if subnet.lease_def %}
	default-lease-time {{ subnet.lease_def }};
	{%- endif %}
	{%- if subnet.lease_max %}
	max-lease-time {{ subnet.lease_max }};
	{%- endif %}
	{%- if subnet.lease_min %}
	min-lease-time {{ subnet.lease_min }};
	{%- endif %}
	{%- if subnet.dns_server %}
	option dhcp6.name-servers {{ subnet.dns_server \| join(', ') }};
	{%- endif %}
	{%- if subnet.nis_domain %}
	option dhcp6.nis-domain-name "{{ subnet.nis_domain }}";
	{%- endif %}
	{%- if subnet.nis_server %}
	option dhcp6.nis-servers {{ subnet.nis_server \| join(', ') }};
	{%- endif %}
	{%- if subnet.nisp_domain %}
	option dhcp6.nisp-domain-name "{{ subnet.nisp_domain }}";
	{%- endif %}
	{%- if subnet.nisp_server %}
	option dhcp6.nisp-servers {{ subnet.nisp_server \| join(', ') }};
	{%- endif %}
	{%- if subnet.sip_address %}
	option dhcp6.sip-servers-addresses {{ subnet.sip_address \| join(', ') }};
	{%- endif %}
	{%- if subnet.sip_hostname %}
	option dhcp6.sip-servers-names {{ subnet.sip_hostname \| join(', ') }};
	{%- endif %}
	{%- if subnet.sntp_server %}
	option dhcp6.sntp-servers {{ subnet.sntp_server \| join(', ') }};
	{%- endif %}
	{%- for host in subnet.static_mapping %}
	{% if not host.disabled -%}
	host {{ network.name }}_{{ host.name }} {
	host-identifier option dhcp6.client-id {{ host.client_identifier }};
	fixed-address6 {{ host.ipv6_address }};
	}
	{%- endif %}
	{%- endfor %}
	}
	{%- endfor %}
	}
	{%- endif %}
	{% endfor %}

	"""

	daemon_tmpl = """
	### Autogenerated by dhcp_server.py ###

	# sourced by /etc/init.d/isc-dhcpv6-server

	DHCPD_CONF=/etc/dhcp/dhcpdv6.conf
	DHCPD_PID=/var/run/dhcpdv6.pid
	OPTIONS="-6 -lf {{ lease_file }}"
	INTERFACES=""
	"""

	default_config_data = {
	'lease_file': lease_file,
	'preference': '',
	'disabled': False,
	'shared_network': []
	}

	def get_config():
	dhcpv6 = default_config_data
	conf = Config()
	if not conf.exists('service dhcpv6-server'):
	return None
	else:
	conf.set_level('service dhcpv6-server')

	# Check for global disable of DHCPv6 service
	if conf.exists('disable'):
	dhcpv6['disabled'] = True
	return dhcpv6

	# Preference of this DHCPv6 server compared with others
	if conf.exists('preference'):
	dhcpv6['preference'] = conf.return_value('preference')

	# check for multiple, shared networks served with DHCPv6 addresses
	if conf.exists('shared-network-name'):
	for network in conf.list_nodes('shared-network-name'):
	conf.set_level('service dhcpv6-server shared-network-name {0}'.format(network))
	config = {
	'name': network,
	'disabled': False,
	'subnet': []
	}

	# If disabled, the shared-network configuration becomes inactive
	if conf.exists('disable'):
	config['disabled'] = True

	# check for multiple subnet configurations in a shared network
	if conf.exists('subnet'):
	for net in conf.list_nodes('subnet'):
	conf.set_level('service dhcpv6-server shared-network-name {0} subnet {1}'.format(network, net))
	subnet = {
	'network': net,
	'range6_prefix': [],
	'range6': [],
	'default_router': '',
	'dns_server': [],
	'domain_name': '',
	'domain_search': [],
	'lease_def': '',
	'lease_min': '',
	'lease_max': '',
	'nis_domain': '',
	'nis_server': [],
	'nisp_domain': '',
	'nisp_server': [],
	'sip_address': [],
	'sip_hostname': [],
	'sntp_server': [],
	'static_mapping': []
	}

	# For any subnet on which addresses will be assigned dynamically, there must be at
	# least one address range statement. The range statement gives the lowest and highest
	# IP addresses in a range. All IP addresses in the range should be in the subnet in
	# which the range statement is declared.
	if conf.exists('address-range prefix'):
	for prefix in conf.list_nodes('address-range prefix'):
	range = {
	'prefix': prefix,
	'temporary': False
	}

	# Address range will be used for temporary addresses
	if conf.exists('address-range prefix {0} temporary'.format(range['prefix'])):
	range['temporary'] = True

	# Append to subnet temporary range6 list
	subnet['range6_prefix'].append(range)

	if conf.exists('address-range start'):
	for range in conf.list_nodes('address-range start'):
	range = {
	'start': range,
	'stop': conf.return_value('address-range start {0} stop'.format(range))
	}

	# Append to subnet range6 list
	subnet['range6'].append(range)

	# The domain-search option specifies a 'search list' of Domain Names to be used
	# by the client to locate not-fully-qualified domain names.
	if conf.exists('domain-search'):
	for domain in conf.return_values('domain-search'):
	subnet['domain_search'].append('"' + domain + '"')

	# IPv6 address valid lifetime
	# (at the end the address is no longer usable by the client)
	# (set to 30 days, the usual IPv6 default)
	if conf.exists('lease-time default'):
	subnet['lease_def'] = conf.return_value('lease-time default')

	# Time should be the maximum length in seconds that will be assigned to a lease.
	# The only exception to this is that Dynamic BOOTP lease lengths, which are not
	# specified by the client, are not limited by this maximum.
	if conf.exists('lease-time maximum'):
	subnet['lease_max'] = conf.return_value('lease-time maximum')

	# Time should be the minimum length in seconds that will be assigned to a lease
	if conf.exists('lease-time minimum'):
	subnet['lease_min'] = conf.return_value('lease-time minimum')

	# Specifies a list of Domain Name System name servers available to the client.
	# Servers should be listed in order of preference.
	if conf.exists('name-server'):
	subnet['dns_server'] = conf.return_values('name-server')

	# Ancient NIS (Network Information Service) domain name
	if conf.exists('nis-domain'):
	subnet['nis_domain'] = conf.return_value('nis-domain')

	# Ancient NIS (Network Information Service) servers
	if conf.exists('nis-server'):
	subnet['nis_server'] = conf.return_values('nis-server')

	# Ancient NIS+ (Network Information Service) domain name
	if conf.exists('nisplus-domain'):
	subnet['nisp_domain'] = conf.return_value('nisplus-domain')

	# Ancient NIS+ (Network Information Service) servers
	if conf.exists('nisplus-server'):
	subnet['nisp_server'] = conf.return_values('nisplus-server')

	# Prefix Delegation (RFC 3633)
	if conf.exists('prefix-delegation'):
	print('TODO: This option is actually not implemented right now!')

	# Local SIP server that is to be used for all outbound SIP requests - IPv6 address
	if conf.exists('sip-server-address'):
	subnet['sip_address'] = conf.return_values('sip-server-address')

	# Local SIP server that is to be used for all outbound SIP requests - hostname
	if conf.exists('sip-server-name'):
	for hostname in conf.return_values('sip-server-name'):
	subnet['sip_hostname'].append('"' + hostname + '"')

	# List of local SNTP servers available for the client to synchronize their clocks
	if conf.exists('sntp-server'):
	subnet['sntp_server'] = conf.return_values('sntp-server')

	#
	# Static DHCP v6 leases
	#
	if conf.exists('static-mapping'):
	for mapping in conf.list_nodes('static-mapping'):
	conf.set_level('service dhcpv6-server shared-network-name {0} subnet {1} static-mapping {2}'.format(network, net, mapping))
	mapping = {
	'name': mapping,
	'disabled': False,
	'ipv6_address': '',
	'client_identifier': '',
	}

	# This static lease is disabled
	if conf.exists('disable'):
	mapping['disabled'] = True

	# IPv6 address used for this DHCP client
	if conf.exists('ipv6-address'):
	mapping['ipv6_address'] = conf.return_value('ipv6-address')

	# This option specifies the client’s DUID identifier. DUIDs are similar but different from DHCPv4 client identifiers
	if conf.exists('identifier'):
	mapping['client_identifier'] = conf.return_value('identifier')

	# append static mapping configuration tu subnet list
	subnet['static_mapping'].append(mapping)

	# append subnet configuration to shared network subnet list
	config['subnet'].append(subnet)


	# append shared network configuration to config dictionary
	dhcpv6['shared_network'].append(config)

	return dhcpv6

	def verify(dhcpv6):
	if dhcpv6 is None:
	return None

	if dhcpv6['disabled']:
	return None

	# If DHCP is enabled we need one share-network
	if len(dhcpv6['shared_network']) == 0:
	raise ConfigError('No DHCPv6 shared networks configured.\n' \
	'At least one DHCPv6 shared network must be configured.')

	# Inspect shared-network/subnet
	subnets = []
	listen_ok = False

	for network in dhcpv6['shared_network']:
	# A shared-network requires a subnet definition
	if len(network['subnet']) == 0:
	raise ConfigError('No DHCPv6 lease subnets configured for {0}. At least one\n' \
	'lease subnet must be configured for each shared network.'.format(network['name']))

	range6_start = []
	range6_stop = []
	for subnet in network['subnet']:
	# Ususal range declaration with a start and stop address
	for range6 in subnet['range6']:
	# shorten names
	start = range6['start']
	stop = range6['stop']

	# DHCPv6 stop address is required
	if start and not stop:
	raise ConfigError('DHCPv6 range stop address for start {0} is not defined!'.format(start))

	# Start address must be inside network
	if not ipaddress.ip_address(start) in ipaddress.ip_network(subnet['network']):
	raise ConfigError('DHCPv6 range start address {0} is not in subnet {1}\n' \
	'specified for shared network {2}!'.format(start, subnet['network'], network['name']))

	# Stop address must be inside network
	if not ipaddress.ip_address(stop) in ipaddress.ip_network(subnet['network']):
	raise ConfigError('DHCPv6 range stop address {0} is not in subnet {1}\n' \
	'specified for shared network {2}!'.format(stop, subnet['network'], network['name']))

	# Stop address must be greater or equal to start address
	if not ipaddress.ip_address(stop) >= ipaddress.ip_address(start):
	raise ConfigError('DHCPv6 range stop address {0} must be greater or equal\n' \
	'to the range start address {1}!'.format(stop, 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('Conflicting DHCPv6 lease range:\n' \
	'Pool start address {0} defined multipe times!'.format(start))
	else:
	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('Conflicting DHCPv6 lease range:\n' \
	'Pool stop address {0} defined multipe times!'.format(stop))
	else:
	range6_stop.append(stop)

	# We also have prefixes that require checking
	for prefix in subnet['range6_prefix']:
	# If configured prefix does not match our subnet, we have to check that it's inside
	if ipaddress.ip_network(prefix['prefix']) != ipaddress.ip_network(subnet['network']):
	# Configured prefixes must be inside our network
	if not ipaddress.ip_network(prefix['prefix']) in ipaddress.ip_network(subnet['network']):
	raise ConfigError('DHCPv6 prefix {0} is not in subnet {1}\n' \
	'specified for shared network {2}!'.format(prefix['prefix'], subnet['network'], network['name']))

	# DHCPv6 requires at least one configured address range or one static mapping
	if not network['disabled']:
	if vyos.validate.is_subnet_connected(subnet['network']):
	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 = ipaddress.ip_network(subnet['network'])
	for n in subnets:
	net2 = ipaddress.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):
	if dhcpv6 is None:
	return None

	if dhcpv6['disabled']:
	print('Warning: DHCPv6 server will be deactivated because it is disabled')
	return None

	tmpl = jinja2.Template(config_tmpl)
	config_text = tmpl.render(dhcpv6)
	with open(config_file, 'w') as f:
	f.write(config_text)

	tmpl = jinja2.Template(daemon_tmpl)
	config_text = tmpl.render(dhcpv6)
	with open(daemon_config_file, 'w') as f:
	f.write(config_text)

	return None

	def apply(dhcpv6):
	if (dhcpv6 is None) or dhcpv6['disabled']:
	# DHCP server is removed in the commit
	os.system('sudo systemctl stop isc-dhcpv6-server.service')
	if os.path.exists(config_file):
	os.unlink(config_file)
	if os.path.exists(daemon_config_file):
	os.unlink(daemon_config_file)
	else:
	# If our file holding DHCPv6 leases does yet not exist - create it
	if not os.path.exists(lease_file):
	os.mknod(lease_file)

	os.system('sudo systemctl restart isc-dhcpv6-server.service')

	return None

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

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