BMP Collector Misinterprets Asymmetric ADD-PATH Negotiation Leading to Incorrect Prefix Parsing

[nashabtayev-dn]

In a scenario where BGP ADD-PATH is asymmetrically configured:

One peer advertises send-only (2)
The other peer advertises receive-only (1)

This is a valid ADD-PATH negotiation per RFC 7911, and multiple paths should be exchanged successfully.

However, the BMP collector incorrectly interprets this combination as no ADD-PATH capability negotiated, due to a faulty condition in the code that expects the capability value to be greater than 3.

As a result:

Prefixes received with ADD-PATH IDs are not recognized as valid ADD-PATH updates
The collector does not expect path identifiers
This leads to incorrect parsing and misrepresentation of prefixes in the database

[sbezverk]

@nashabtayev-dn thank you for reporting the issue, please either provide the configuration of bgp speakers to reproduce this issue or reproduce it in your environment while running gobmp with --v=9 verbosity.