[PATCH] BGP: Add support for BGP hostname capability

[Vincent Bernat]

 ❦  3 février 2021 23:37 +01, Ondrej Zajicek:

> 1) Hostname has similar role like router id. It seems to me that there
> should be global hostname config property, like config->router_id,
> initialized like router_id in global_commit().

Done. Use `hostname "bla"`

> 2) Consequently, there should be global option to set it, and it should
> report in 'show status'.

Done.

> 3) Function calling uname() should be probably somewhere in
> sysdep/unix/ code

Not done. I don't know exactly where I would put it and it would be a
trivial wrapper.

> 4) The hostname field in bgp_caps should be ptr, allocated based on
> length, instead of preallocatted full-length buffer.

Done. I think I have used the pools correctly.

> 5) As Job Snijders wrote, the capability should be disabled by
> default.

Done. Can be enabled with `advertise hostname yes`.

> 6) Received hostname should be treated for unsafe characters like text
> from RFC 8203 (shutdown communication), see bgp_handle_message().

Done.

Also, reload works, but as I didn't write anything for that, it's a bit
a mystery how BIRD knows there is a change.