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protocols_bgp.py
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protocols_bgp.py
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#!/usr/bin/env python3
#
# Copyright (C) 2020-2021 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 vyos.config import Config
from vyos.configdict import dict_merge
from vyos.template import render
from vyos.template import render_to_string
from vyos.util import call
from vyos.util import dict_search
from vyos import ConfigError
from vyos import frr
from vyos import airbag
airbag.enable()
config_file = r'/tmp/bgp.frr'
DEBUG = os.path.exists('/tmp/bgp.debug')
if DEBUG:
import logging
lg = logging.getLogger("vyos.frr")
lg.setLevel(logging.DEBUG)
ch = logging.StreamHandler()
lg.addHandler(ch)
def get_config():
conf = Config()
base = ['protocols', 'bgp']
bgp = conf.get_config_dict(base, key_mangling=('-', '_'), get_first_key=True)
if not conf.exists(base):
return bgp
# We also need some additional information from the config,
# prefix-lists and route-maps for instance.
base = ['policy']
tmp = conf.get_config_dict(base, key_mangling=('-', '_'))
# As we only support one ASN (later checked in begin of verify()) we add the
# new information only to the first AS number
asn = next(iter(bgp))
# Merge policy dict into bgp dict
bgp[asn] = dict_merge(tmp, bgp[asn])
return bgp
def verify(bgp):
if not bgp:
return None
# Check if declared more than one ASN
if len(bgp) > 1:
raise ConfigError('Only one BGP AS number can be defined!')
for asn, asn_config in bgp.items():
# Common verification for both peer-group and neighbor statements
for neighbor in ['neighbor', 'peer_group']:
# bail out early if there is no neighbor or peer-group statement
# this also saves one indention level
if neighbor not in asn_config:
continue
for peer, peer_config in asn_config[neighbor].items():
# Only regular "neighbor" statement can have a peer-group set
# Check if the configure peer-group exists
if 'peer_group' in peer_config:
peer_group = peer_config['peer_group']
if peer_group not in asn_config['peer_group']:
raise ConfigError(f'Specified peer-group "{peer_group}" for '\
f'neighbor "{neighbor}" does not exist!')
# Some checks can/must only be done on a neighbor and nor a peer-group
if neighbor == 'neighbor':
# remote-as must be either set explicitly for the neighbor
# or for the entire peer-group
if 'remote_as' not in peer_config:
if 'peer_group' not in peer_config or 'remote_as' not in asn_config['peer_group'][peer_config['peer_group']]:
raise ConfigError('Remote AS must be set for neighbor or peer-group!')
for afi in ['ipv4_unicast', 'ipv6_unicast']:
# Bail out early if address family is not configured
if 'address_family' not in peer_config or afi not in peer_config['address_family']:
continue
afi_config = peer_config['address_family'][afi]
# Validate if configured Prefix list exists
if 'prefix_list' in afi_config:
for tmp in ['import', 'export']:
if tmp not in afi_config['prefix_list']:
# bail out early
continue
# get_config_dict() mangles all '-' characters to '_' this is legitim, thus all our
# compares will run on '_' as also '_' is a valid name for a prefix-list
prefix_list = afi_config['prefix_list'][tmp].replace('-', '_')
if afi == 'ipv4_unicast':
if dict_search(f'policy.prefix_list.{prefix_list}', asn_config) == None:
raise ConfigError(f'prefix-list "{prefix_list}" used for "{tmp}" does not exist!')
elif afi == 'ipv6_unicast':
if dict_search(f'policy.prefix_list6.{prefix_list}', asn_config) == None:
raise ConfigError(f'prefix-list6 "{prefix_list}" used for "{tmp}" does not exist!')
if 'route_map' in afi_config:
for tmp in ['import', 'export']:
if tmp in afi_config['route_map']:
# get_config_dict() mangles all '-' characters to '_' this is legitim, thus all our
# compares will run on '_' as also '_' is a valid name for a route-map
route_map = afi_config['route_map'][tmp].replace('-', '_')
if dict_search(f'policy.route_map.{route_map}', asn_config) == None:
raise ConfigError(f'route-map "{route_map}" used for "{tmp}" does not exist!')
return None
def generate(bgp):
if not bgp:
bgp['new_frr_config'] = ''
return None
# only one BGP AS is supported, so we can directly send the first key
# of the config dict
asn = list(bgp.keys())[0]
bgp[asn]['asn'] = asn
# render(config) not needed, its only for debug
render(config_file, 'frr/bgp.frr.tmpl', bgp[asn])
bgp['new_frr_config'] = render_to_string('frr/bgp.frr.tmpl', bgp[asn])
return None
def apply(bgp):
# Save original configuration prior to starting any commit actions
frr_cfg = frr.FRRConfig()
frr_cfg.load_configuration(daemon='bgpd')
frr_cfg.modify_section(f'router bgp \S+', '')
frr_cfg.add_before(r'(ip prefix-list .*|route-map .*|line vty)', bgp['new_frr_config'])
frr_cfg.commit_configuration(daemon='bgpd')
# If FRR config is blank, rerun the blank commit x times due to frr-reload
# behavior/bug not properly clearing out on one commit.
if bgp['new_frr_config'] == '':
for a in range(5):
frr_cfg.commit_configuration(daemon='bgpd')
# Debugging
if DEBUG:
from pprint import pprint
print('')
print('--------- DEBUGGING ----------')
pprint(dir(frr_cfg))
print('Existing config:\n')
for line in frr_cfg.original_config:
print(line)
print(f'Replacement config:\n')
print(f'{bgp["new_frr_config"]}')
print(f'Modified config:\n')
print(f'{frr_cfg}')
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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