Polling IPv6 BGP peers fails for Cisco devices with IPv6 peers in VRF, but no IPv6 peers in default VRF

[ajsiersema]

The problem

( related to #14105 , but for IPv6 BGP peers)

If a Cisco device has VRFs defined and IPv6 BGP peers configured in those VRFs, but no IPv6 BGP sessions/peers in the default VRF, a SNMP (v3) walk without context will not find any cbgpPeer2RemoteAs. The code at the top of includes/polling/bgp-peers.inc.php populating $peer_data_check will return an empty Array:

$peer_data_check = snmpwalk_cache_oid($device, 'cbgpPeer2RemoteAs', [], 'CISCO-BGP4-MIB');

This causes the code near line 34 that checks for an empty $peer_data_check to set the device type/class to generic:

        if (empty($peer_data_check)) {
             $peer_data_check = snmpwalk_cache_oid($device, 'bgpPeerRemoteAs', [], 'BGP4-MIB');
             $generic = true;
         }

IPv6 BGP peers will never be polled, because the network OS specific code is skipped due to the if ($generic) { at the top of the checks. The } elseif ($device['os_group'] == 'cisco') { further below will never execute, and instead of using the CISCO-BGP4-MIB, the code will use the default BGP4-MIB, which won't find the IPv6 peers.

Output of ./validate.php

===========================================
Component | Version
--------- | -------
LibreNMS  | 23.4.0 (2023-04-07T01:52:52+02:00)
DB Schema | 2023_03_14_130653_migrate_empty_user_funcs_to_null (249)
PHP       | 8.2.4
Python    | 3.9.14
Database  | MariaDB 10.5.16-MariaDB
RRDTool   | 1.7.2
SNMP      | 5.9.1
===========================================

[OK]    Composer Version: 2.5.4
[OK]    Dependencies up-to-date.
[OK]    Database connection successful
[OK]    Database Schema is current
[OK]    SQL Server meets minimum requirements
[OK]    lower_case_table_names is enabled
[OK]    MySQL engine is optimal
[OK]    Database and column collations are correct
[OK]    Database schema correct
[OK]    MySQl and PHP time match
[OK]    Distributed Polling setting is enabled globally
[OK]    Connected to rrdcached
[OK]    Active pollers found
[OK]    Dispatcher Service is enabled
[OK]    Locks are functional
[OK]    No python wrapper pollers found
[OK]    Redis is functional
[OK]    rrdtool version ok
[OK]    Connected to rrdcached
[WARN]  Your local git contains modified files, this could prevent automatic updates.
        [FIX]: 
        You can fix this with ./scripts/github-remove
        Modified Files:
         includes/polling/bgp-peers.inc.php

What was the last working version of LibreNMS?

No response

Anything in the logs that might be useful for us?

No response