Support for extended NLRI encoding for BGP add-path

[mengkoonlim]

https://tools.ietf.org/html/rfc7911#page-3

If BGP addpath is enabled, the NLRI encoding has a 4 byte value prepended for each NLRI, to indicate the Path ID.

             +--------------------------------+
              | Path Identifier (4 octets)     |
              +--------------------------------+
              | Length (1 octet)               |
              +--------------------------------+
              | Prefix (variable)              |
              +--------------------------------+

This resulted in wrong NLRI parsing by pbgpp

thanks

[cmoeller-dx]

Hello @mengkoonlim ,
we are currently working on this problem.
Could you provide us with a pcap file containing this particular message for testing purposes?

It would be nice if the file contains a message like you mentioned in issue No. 37. (#38)
Thank you.

[mengkoonlim]

The attached pcap has message for BGP add-path NLRI path-iad and Prefix Length 0 mentioned in issue no.37
thanks!
sample.pcap.gz