vxlan: T1636: initial rewrite with XML and Python

Tested using:
Site 1 (VyOS 1.2.2)
-------------------
 set interfaces vxlan vxlan100 address '10.10.10.2/24'
 set interfaces vxlan vxlan100 remote '172.18.201.10'
 set interfaces vxlan vxlan100 vni '100'

Site 2 (rewrite)
----------------
 set interfaces vxlan vxlan100 address '10.10.10.1/24'
 set interfaces vxlan vxlan100 description 'VyOS VXLAN'
 set interfaces vxlan vxlan100 remote '172.18.202.10'
 set interfaces vxlan vxlan100 vni '100'

1 files changed, 208 insertions, 0 deletions

diff --git a/src/conf_mode/interface-vxlan.py b/src/conf_mode/interface-vxlan.py
new file mode 100755
index 000000000..59022238e
--- /dev/null
+++ b/src/conf_mode/interface-vxlan.py
@@ -0,0 +1,208 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2019 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/>.
+#
+
+from os import environ
+from sys import exit
+from copy import deepcopy
+
+from vyos.configdict import list_diff
+from vyos.config import Config
+from vyos.ifconfig import VXLANIf, Interface
+from vyos.interfaces import get_type_of_interface
+from vyos import ConfigError
+from netifaces import interfaces
+
+default_config_data = {
+    'address': [],
+    'address_remove': [],
+    'deleted': False,
+    'description': '',
+    'disable': False,
+    'group': '',
+    'intf': '',
+    'ip_arp_cache_tmo': 30,
+    'ip_proxy_arp': 0,
+    'link': '',
+    'mtu': 1450,
+    'remote': '',
+    'remote_port': 8472 # The Linux implementation of VXLAN pre-dates
+                        # the IANA's selection of a standard destination port
+}
+
+
+def get_config():
+    vxlan = deepcopy(default_config_data)
+    conf = Config()
+
+    # determine tagNode instance
+    try:
+        vxlan['intf'] = environ['VYOS_TAGNODE_VALUE']
+    except KeyError as E:
+        print("Interface not specified")
+
+    # Check if interface has been removed
+    if not conf.exists('interfaces vxlan ' + vxlan['intf']):
+        vxlan['deleted'] = True
+        return vxlan
+
+    # set new configuration level
+    conf.set_level('interfaces vxlan ' + vxlan['intf'])
+
+    # retrieve configured interface addresses
+    if conf.exists('address'):
+        vxlan['address'] = conf.return_values('address')
+
+    # Determine interface addresses (currently effective) - to determine which
+    # address is no longer valid and needs to be removed from the interface
+    eff_addr = conf.return_effective_values('address')
+    act_addr = conf.return_values('address')
+    vxlan['address_remove'] = list_diff(eff_addr, act_addr)
+
+    # retrieve interface description
+    if conf.exists('description'):
+        vxlan['description'] = conf.return_value('description')
+
+    # Disable this interface
+    if conf.exists('disable'):
+        vxlan['disable'] = True
+
+    # VXLAN multicast grou
+    if conf.exists('group'):
+        vxlan['group'] = conf.return_value('group')
+
+    # ARP cache entry timeout in seconds
+    if conf.exists('ip arp-cache-timeout'):
+        vxlan['ip_arp_cache_tmo'] = int(conf.return_value('ip arp-cache-timeout'))
+
+    # Enable proxy-arp on this interface
+    if conf.exists('ip enable-proxy-arp'):
+        vxlan['ip_proxy_arp'] = 1
+
+    # VXLAN underlay interface
+    if conf.exists('link'):
+        vxlan['link'] = conf.return_value('link')
+
+    # Maximum Transmission Unit (MTU)
+    if conf.exists('mtu'):
+        vxlan['mtu'] = int(conf.return_value('mtu'))
+
+    # Remote address of VXLAN tunnel
+    if conf.exists('remote'):
+        vxlan['remote'] = conf.return_value('remote')
+
+    # Remote port of VXLAN tunnel
+    if conf.exists('port'):
+        vxlan['remote_port'] = int(conf.return_value('port'))
+
+    # Virtual Network Identifier
+    if conf.exists('vni'):
+        vxlan['vni'] = conf.return_value('vni')
+
+    return vxlan
+
+
+def verify(vxlan):
+    if vxlan['deleted']:
+        # bail out early
+        return None
+
+    if vxlan['mtu'] < 1500:
+        print('WARNING: RFC7348 recommends VXLAN tunnels preserve a 1500 byte MTU')
+
+    if vxlan['group'] and not vxlan['link']:
+        raise ConfigError('Multicast VXLAN requires an underlaying interface ')
+
+    if not (vxlan['group'] or vxlan['remote']):
+        raise ConfigError('Group or remote must be configured')
+
+    if not vxlan['vni']:
+        raise ConfigError('Must configure VNI for VXLAN')
+
+    if vxlan['link']:
+        # VXLAN adds a 50 byte overhead - we need to check the underlaying MTU
+        # if our configured MTU is at least 50 bytes less
+        underlay_mtu = int(Interface(vxlan['link']).mtu)
+        if underlay_mtu < (vxlan['mtu'] + 50):
+            raise ConfigError('VXLAN has a 50 byte overhead, underlaying device ' \
+                              'MTU is to small ({})'.format(underlay_mtu))
+
+    return None
+
+
+def generate(vxlan):
+    return None
+
+
+def apply(vxlan):
+    # Check if the VXLAN interface already exists
+    if vxlan['intf'] in interfaces():
+        v = VXLANIf(vxlan['intf'])
+        # VXLAN is super picky and the tunnel always needs to be recreated,
+        # thus we can simply always delete it first.
+        v.remove()
+
+    if not vxlan['deleted']:
+        # VXLAN interface needs to be created on-block
+        # instead of passing a ton of arguments, I just use a dict
+        # that is managed by vyos.ifconfig
+        conf = deepcopy(VXLANIf.get_config())
+
+        # Assign VXLAN instance configuration parameters to config dict
+        conf['vni'] = vxlan['vni']
+        conf['group'] = vxlan['group']
+        conf['dev'] = vxlan['link']
+        conf['remote'] = vxlan['remote']
+        conf['port'] = vxlan['remote_port']
+
+        # Finally create the new interface
+        v = VXLANIf(vxlan['intf'], config=conf)
+        # update interface description used e.g. by SNMP
+        v.ifalias = vxlan['description']
+        # Maximum Transfer Unit (MTU)
+        v.mtu = vxlan['mtu']
+
+        # configure ARP cache timeout in milliseconds
+        v.arp_cache_tmp = vxlan['ip_arp_cache_tmo']
+        # Enable proxy-arp on this interface
+        v.proxy_arp = vxlan['ip_proxy_arp']
+
+        # Configure interface address(es)
+        # - not longer required addresses get removed first
+        # - newly addresses will be added second
+        for addr in vxlan['address_remove']:
+            v.del_addr(addr)
+        for addr in vxlan['address']:
+            v.add_addr(addr)
+
+        # As the bond interface is always disabled first when changing
+        # parameters we will only re-enable the interface if it is not
+        # administratively disabled
+        if not vxlan['disable']:
+            v.state='up'
+
+    return None
+
+
+if __name__ == '__main__':
+    try:
+        c = get_config()
+        verify(c)
+        generate(c)
+        apply(c)
+    except ConfigError as e:
+        print(e)
+        exit(1)