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interfaces-vxlan.py
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interfaces-vxlan.py
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#!/usr/bin/env python3
#
# Copyright (C) 2019-2022 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 netifaces import interfaces
from vyos.config import Config
from vyos.configdict import get_interface_dict
from vyos.configdict import leaf_node_changed
from vyos.configverify import verify_address
from vyos.configverify import verify_bridge_delete
from vyos.configverify import verify_mtu_ipv6
from vyos.configverify import verify_redirect
from vyos.configverify import verify_source_interface
from vyos.ifconfig import Interface
from vyos.ifconfig import VXLANIf
from vyos.template import is_ipv6
from vyos import ConfigError
from vyos import airbag
airbag.enable()
def get_config(config=None):
"""
Retrive CLI config as dictionary. Dictionary can never be empty, as at least
the interface name will be added or a deleted flag
"""
if config:
conf = config
else:
conf = Config()
base = ['interfaces', 'vxlan']
vxlan = get_interface_dict(conf, base)
# VXLAN interfaces are picky and require recreation if certain parameters
# change. But a VXLAN interface should - of course - not be re-created if
# it's description or IP address is adjusted. Feels somehow logic doesn't it?
for cli_option in ['external', 'gpe', 'group', 'port', 'remote',
'source-address', 'source-interface', 'vni',
'parameters ip dont-fragment', 'parameters ip tos',
'parameters ip ttl']:
if leaf_node_changed(conf, cli_option.split()):
vxlan.update({'rebuild_required': {}})
# We need to verify that no other VXLAN tunnel is configured when external
# mode is in use - Linux Kernel limitation
conf.set_level(base)
vxlan['other_tunnels'] = conf.get_config_dict([], key_mangling=('-', '_'),
get_first_key=True,
no_tag_node_value_mangle=True)
# This if-clause is just to be sure - it will always evaluate to true
ifname = vxlan['ifname']
if ifname in vxlan['other_tunnels']:
del vxlan['other_tunnels'][ifname]
if len(vxlan['other_tunnels']) == 0:
del vxlan['other_tunnels']
return vxlan
def verify(vxlan):
if 'deleted' in vxlan:
verify_bridge_delete(vxlan)
return None
if int(vxlan['mtu']) < 1500:
print('WARNING: RFC7348 recommends VXLAN tunnels preserve a 1500 byte MTU')
if 'group' in vxlan:
if 'source_interface' not in vxlan:
raise ConfigError('Multicast VXLAN requires an underlaying interface')
verify_source_interface(vxlan)
if not any(tmp in ['group', 'remote', 'source_address'] for tmp in vxlan):
raise ConfigError('Group, remote or source-address must be configured')
if 'vni' not in vxlan and 'external' not in vxlan:
raise ConfigError(
'Must either configure VXLAN "vni" or use "external" CLI option!')
if {'external', 'vni'} <= set(vxlan):
raise ConfigError('Can not specify both "external" and "VNI"!')
if {'external', 'other_tunnels'} <= set(vxlan):
other_tunnels = ', '.join(vxlan['other_tunnels'])
raise ConfigError(f'Only one VXLAN tunnel is supported when "external" '\
f'CLI option is used. Additional tunnels: {other_tunnels}')
if 'gpe' in vxlan and 'external' not in vxlan:
raise ConfigError(f'VXLAN-GPE is only supported when "external" '\
f'CLI option is used.')
if 'source_interface' in vxlan:
# VXLAN adds at least an overhead of 50 byte - we need to check the
# underlaying device if our VXLAN package is not going to be fragmented!
vxlan_overhead = 50
if 'source_address' in vxlan and is_ipv6(vxlan['source_address']):
# IPv6 adds an extra 20 bytes overhead because the IPv6 header is 20
# bytes larger than the IPv4 header - assuming no extra options are
# in use.
vxlan_overhead += 20
lower_mtu = Interface(vxlan['source_interface']).get_mtu()
if lower_mtu < (int(vxlan['mtu']) + vxlan_overhead):
raise ConfigError(f'Underlaying device MTU is to small ({lower_mtu} '\
f'bytes) for VXLAN overhead ({vxlan_overhead} bytes!)')
# Check for mixed IPv4 and IPv6 addresses
protocol = None
if 'source_address' in vxlan:
if is_ipv6(vxlan['source_address']):
protocol = 'ipv6'
else:
protocol = 'ipv4'
if 'remote' in vxlan:
error_msg = 'Can not mix both IPv4 and IPv6 for VXLAN underlay'
for remote in vxlan['remote']:
if is_ipv6(remote):
if protocol == 'ipv4':
raise ConfigError(error_msg)
protocol = 'ipv6'
else:
if protocol == 'ipv6':
raise ConfigError(error_msg)
protocol = 'ipv4'
verify_mtu_ipv6(vxlan)
verify_address(vxlan)
verify_redirect(vxlan)
return None
def generate(vxlan):
return None
def apply(vxlan):
# Check if the VXLAN interface already exists
if 'rebuild_required' in vxlan or 'delete' in vxlan:
if vxlan['ifname'] in interfaces():
v = VXLANIf(vxlan['ifname'])
# VXLAN is super picky and the tunnel always needs to be recreated,
# thus we can simply always delete it first.
v.remove()
if 'deleted' not in vxlan:
# Finally create the new interface
v = VXLANIf(**vxlan)
v.update(vxlan)
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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