Implement software version capability for BGP

https://datatracker.ietf.org/doc/html/draft-abraitis-bgp-version-capability

This is already implemented by FRR, GoBGP, freertr, Wireshark, some more.

E.g.:

```
$ vtysh -c 'show bgp neighbor 127.0.0.1 json' | jq '."127.0.0.1".neighborCapabilities.softwareVersion'
{
  "advertisedSoftwareVersion": "FRRouting/10.2-dev-MyOwnFRRVersion-g8ca262943f",
  "receivedSoftwareVersion": "ExaBGP/feature/bgp_software_version_capability-e510e8c6b4d6c8651"
}
```

Signed-off-by: Donatas Abraitis <[email protected]>

src/exabgp/bgp/message/open/capability/capabilities.py

@@ -22,6 +22,7 @@
 from exabgp.bgp.message.open.capability.refresh import EnhancedRouteRefresh
 from exabgp.bgp.message.open.capability.extended import ExtendedMessage
 from exabgp.bgp.message.open.capability.hostname import HostName
+from exabgp.bgp.message.open.capability.software_version import SoftwareVersion
 
 from exabgp.bgp.message.notification import Notify
 
@@ -142,6 +143,12 @@ def _extended_message(self, neighbor):
     def _hostname(self, neighbor):
         self[Capability.CODE.HOSTNAME] = HostName(neighbor['host-name'], neighbor['domain-name'])
 
+    def _software_version(self, neighbor):
+        if not neighbor['capability']['software-version']:
+            return
+
+        self[Capability.CODE.SOFTRWARE_VERSION] = SoftwareVersion()
+
     def _operational(self, neighbor):
         if not neighbor['capability']['operational']:
             return
@@ -163,6 +170,7 @@ def new(self, neighbor, restarted):
         self._operational(neighbor)
         self._extended_message(neighbor)
         self._hostname(neighbor)  # https://datatracker.ietf.org/doc/html/draft-walton-bgp-hostname-capability-02
+        self._software_version(neighbor)  # https://datatracker.ietf.org/doc/html/draft-abraitis-bgp-version-capability
         self._session(neighbor)  # MUST be the last key added, really !?! dict is not ordered !
         return self
 

src/exabgp/bgp/message/open/capability/capability.py

@@ -37,6 +37,7 @@ class _CapabilityCode(int):
     MULTISESSION_CISCO = 0x83  # What Cisco really use for Multisession (yes this is a reserved range in prod !)
 
     HOSTNAME = 0x49  # https://datatracker.ietf.org/doc/html/draft-walton-bgp-hostname-capability-02
+    SOFTWARE_VERSION = 0x4B  # https://datatracker.ietf.org/doc/html/draft-abraitis-bgp-version-capability
     OPERATIONAL = 0xB9  # ExaBGP only ...
 
     # Internal
@@ -61,6 +62,7 @@ class _CapabilityCode(int):
         MULTISESSION_CISCO: 'cisco-multi-sesion',
         AIGP: 'aigp',
         HOSTNAME: 'hostname',
+        SOFTWARE_VERSION: 'software-version',
     }
 
     def __new__(cls, value):
@@ -105,6 +107,7 @@ class CODE(int):
         ROUTE_REFRESH_CISCO =      _CapabilityCode(_CapabilityCode.ROUTE_REFRESH_CISCO)
         MULTISESSION_CISCO =       _CapabilityCode(_CapabilityCode.MULTISESSION_CISCO)
         HOSTNAME =                 _CapabilityCode(_CapabilityCode.HOSTNAME)
+        SOFTRWARE_VERSION =        _CapabilityCode(_CapabilityCode.SOFTWARE_VERSION)
         OPERATIONAL =              _CapabilityCode(_CapabilityCode.OPERATIONAL)
         AIGP =                     _CapabilityCode(_CapabilityCode.AIGP)
         # fmt: on

src/exabgp/bgp/message/open/capability/software_version.py

@@ -0,0 +1,40 @@
+# encoding: utf-8
+"""
+software_version.py
+
+Copyright (c) 2024 Donatas Abraitis. All rights reserved.
+License: 3-clause BSD. (See the COPYRIGHT file)
+"""
+
+# https://datatracker.ietf.org/doc/html/draft-abraitis-bgp-version-capability
+
+
+from exabgp.bgp.message.open.capability.capability import Capability
+from exabgp.version import version
+
+
+@Capability.register()
+class SoftwareVersion(Capability):
+    ID = Capability.CODE.SOFTRWARE_VERSION
+    SOFTWARE_VERSION_MAX_LEN = 64
+
+    def __init__(self):
+        self.software_version = f"ExaBGP/{version}"
+
+    def __str__(self):
+        return f'SoftwareVersion({self.software_version})'
+
+    def json(self):
+        return f'{ "software-version": "{self.software_version}" }'
+
+    def extract(self):
+        software_version = self.software_version.encode('utf-8')
+        if len(software_version) > self.SOFTWARE_VERSION_MAX_LEN:
+            software_version = software_version[: self.SOFTWARE_VERSION_MAX_LEN]
+        return [bytes([len(software_version)]) + software_version]
+
+    @staticmethod
+    def unpack_capability(instance, data, capability=None):  # pylint: disable=W0613
+        l1 = data[0]
+        instance.software_version = data[1 : l1 + 1].decode('utf-8')
+        return instance

src/exabgp/bgp/neighbor.py

@@ -59,6 +59,7 @@ class Capability(dict):
             'route-refresh': 0,
             'nexthop': None,
             'aigp': None,
+            'software-version': None,
         }
 
     defaults = {
@@ -406,7 +407,7 @@ def string(self, with_changes=True):
             '\tmanual-eor %s;\n'
             '%s%s%s%s%s%s%s%s%s%s%s\n'
             '\tcapability {\n'
-            '%s%s%s%s%s%s%s%s%s\t}\n'
+            '%s%s%s%s%s%s%s%s%s%s\t}\n'
             '\tfamily {%s\n'
             '\t}\n'
             '\tnexthop {%s\n'
@@ -446,6 +447,8 @@ def string(self, with_changes=True):
                 '\t\troute-refresh %s;\n' % ('enable' if self['capability']['route-refresh'] else 'disable'),
                 '\t\tgraceful-restart %s;\n'
                 % (self['capability']['graceful-restart'] if self['capability']['graceful-restart'] else 'disable'),
+                '\t\tsoftware-version %s;\n'
+                % ('enable' if self['capability']['software-version'] else 'disable'),
                 '\t\tnexthop %s;\n' % ('enable' if self['capability']['nexthop'] else 'disable'),
                 '\t\tadd-path %s;\n'
                 % (AddPath.string[self['capability']['add-path']] if self['capability']['add-path'] else 'disable'),

src/exabgp/configuration/capability.py

@@ -71,6 +71,7 @@ class ParseCapability(Section):
         '   operational enable|disable;\n'
         '   refresh enable|disable;\n'
         '   extended-message enable|disable;\n'
+        '   software-version enable|disable;\n'
         '}\n'
     )
 
@@ -84,6 +85,7 @@ class ParseCapability(Section):
         'route-refresh': boolean,
         'aigp': boolean,
         'extended-message': boolean,
+        'software-version': boolean,
     }
 
     action = {
@@ -96,6 +98,7 @@ class ParseCapability(Section):
         'route-refresh': 'set-command',
         'aigp': 'set-command',
         'extended-message': 'set-command',
+        'software-version': 'set-command',
     }
 
     default = {
@@ -107,6 +110,7 @@ class ParseCapability(Section):
         'route-refresh': True,
         'aigp': True,
         'extended-message': True,
+        'software-version': False,
     }
 
     name = 'capability'

src/exabgp/configuration/neighbor/__init__.py

@@ -44,6 +44,7 @@
 from exabgp.configuration.neighbor.parser import description
 from exabgp.configuration.neighbor.parser import inherit
 from exabgp.configuration.neighbor.parser import rate_limit
+from exabgp.version import version
 
 from exabgp.environment import getenv
 

tests/decode_test.py

@@ -33,7 +33,7 @@
 from exabgp.bgp.message.update.nlri import NLRI
 
 from exabgp.bgp.message.direction import Direction
- 
+
 from exabgp.logger import log
 from exabgp.environment import getenv
 
@@ -328,6 +328,7 @@ def __init__(self):
                 'aigp': None,
                 'operational': None,
                 'extended-message': True,
+                'software-version': False,
              },
         })