vrf.py
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vrf.py
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	#!/usr/bin/env python3
	#
	# Copyright (C) 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 sys import exit
	from copy import deepcopy
	from subprocess import check_call, CalledProcessError
	from vyos.config import Config
	from vyos.configdict import list_diff
	from vyos import ConfigError

	default_config_data = {
	'bind_to_all': 0,
	'deleted': False,
	'vrf_add': [],
	'vrf_existing': [],
	'vrf_remove': []
	}

	def _cmd(command):
	"""
	Run any arbitrary command on the system
	"""
	try:
	check_call(command.split())
	except CalledProcessError as e:
	pass
	raise ConfigError(f'Error operationg on VRF: {e}')

	def interfaces_with_vrf(match):
	matched = []
	config = Config()
	section = config.get_config_dict('interfaces')
	for type in section:
	interfaces = section[type]
	for name in interfaces:
	interface = interfaces[name]
	if 'vrf' in interface:
	v = interface.get('vrf', '')
	if v == match:
	matched.append(name)
	return matched

	def get_config():
	conf = Config()
	vrf_config = deepcopy(default_config_data)

	cfg_base = ['vrf']
	if not conf.exists(cfg_base):
	# get all currently effetive VRFs and mark them for deletion
	vrf_config['vrf_remove'] = conf.list_effective_nodes(cfg_base + ['name'])
	else:

	# Should services be allowed to bind to all VRFs?
	if conf.exists(['bind-to-all']):
	vrf_config['bind_to_all'] = 1

	# Determine vrf interfaces (currently effective) - to determine which
	# vrf interface is no longer present and needs to be removed
	eff_vrf = conf.list_effective_nodes(cfg_base + ['name'])
	act_vrf = conf.list_nodes(cfg_base + ['name'])
	vrf_config['vrf_remove'] = list_diff(eff_vrf, act_vrf)

	# read in individual VRF definition and build up
	# configuration
	for name in conf.list_nodes(cfg_base + ['name']):
	vrf_inst = {
	'description' : '\0',
	'members': [],
	'name' : name,
	'table' : '',
	'table_mod': False
	}
	conf.set_level(cfg_base + ['name', name])

	if conf.exists(['table']):
	# VRF table can't be changed on demand, thus we need to read in the
	# current and the effective routing table number
	act_table = conf.return_value(['table'])
	eff_table = conf.return_effective_value(['table'])
	vrf_inst['table'] = act_table
	if eff_table and eff_table != act_table:
	vrf_inst['table_mod'] = True

	if conf.exists(['description']):
	vrf_inst['description'] = conf.return_value(['description'])

	# find member interfaces of this particulat VRF
	vrf_inst['members'] = interfaces_with_vrf(name)

	# append individual VRF configuration to global configuration list
	vrf_config['vrf_add'].append(vrf_inst)

	# check VRFs which need to be removed as they are not allowed to have
	# interfaces attached
	tmp = []
	for name in vrf_config['vrf_remove']:
	vrf_inst = {
	'members': [],
	'name' : name,
	}

	# find member interfaces of this particulat VRF
	vrf_inst['members'] = interfaces_with_vrf(name)

	# append individual VRF configuration to temporary configuration list
	tmp.append(vrf_inst)

	# replace values in vrf_remove with list of dictionaries
	# as we need it in verify() - we can't delete a VRF with members attached
	vrf_config['vrf_remove'] = tmp
	return vrf_config

	def verify(vrf_config):
	# ensure VRF is not assigned to any interface
	for vrf in vrf_config['vrf_remove']:
	if len(vrf['members']) > 0:
	raise ConfigError('VRF "{}" can not be deleted as it has active members'.format(vrf['name']))

	# routing table id can't be changed - OS restriction
	for vrf in vrf_config['vrf_add']:
	if vrf['table_mod']:
	raise ConfigError('VRF routing table id modification is not possible')

	# add test to see if routing table already exists or not?

	return None

	def generate(vrf_config):
	return None

	def apply(vrf_config):
	# https://github.com/torvalds/linux/blob/master/Documentation/networking/vrf.txt

	# set the default VRF global behaviour
	bind_all = vrf_config['bind_to_all']
	_cmd(f'sysctl -wq net.ipv4.tcp_l3mdev_accept={bind_all}')
	_cmd(f'sysctl -wq net.ipv4.udp_l3mdev_accept={bind_all}')

	for vrf_name in vrf_config['vrf_remove']:
	if os.path.isdir(f'/sys/class/net/{vrf_name}'):
	_cmd(f'ip link delete dev {vrf_name}')

	for vrf in vrf_config['vrf_add']:
	name = vrf['name']
	table = vrf['table']

	if not os.path.isdir(f'/sys/class/net/{name}'):
	_cmd(f'ip link add {name} type vrf table {table}')
	_cmd(f'ip link set dev {name} up')
	_cmd(f'ip -4 rule add oif {name} lookup {table}')
	_cmd(f'ip -4 rule add iif {name} lookup {table}')
	_cmd(f'ip -6 rule add oif {name} lookup {table}')
	_cmd(f'ip -6 rule add iif {name} lookup {table}')

	# set VRF description for e.g. SNMP monitoring
	with open(f'/sys/class/net/{name}/ifalias', 'w') as f:
	f.write(vrf['description'])

	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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