[PATCH] Netlink on FreeBSD support

[Ondrej Zajicek]

On Sat, Dec 17, 2022 at 01:27:23PM +0000, Alexander Chernikov wrote:
> >> * 0002-FreeBSD-use-interface-index-instead-of-IP-address-wh.patch switches multicast interface specification from ip address to interface index. That allows to avoid iface->sysdep value, which is not filled by netlink.
> > 
> > Nice. Is this supported since long ago, or does it require some recent BSD version?
> > Do you know whether it is supported also in other BSD flavors?
>
> It’s a bit complicated :-)
> 
> FreeBSD:
> IP_MULTICAST_IF - ip_mreqn support was added in [1] @ 2007.
> IP_<ADD|DEL>_MEMBERSHIP - ip_mreqn support was added in [2] @ 2019 / FreeBSD 12.1. All currently supported FreeBSD versions have this functionality in place
> 
> OpenBSD:
> IP_MULTICAST_IF - ip_mreqn support was added in [3] @ 2021
> IP_<ADD|DEL>_MEMBERSHIP - ip_mreqn support was added in [4] @ 2021
> 
> NetBSD:
> IP_MULTICAST_IF,  IP_<ADD|DEL>_MEMBERSHIP uses old API hack, treating 0/8 IPv4 addresses as ifindex. It was added in [5] @ 2001

Thanks for the overview!

So we can assume that the ip_mreqn API is available since FreeBSD 12.1
and OpenBSD 6.9 and enable CONFIG_USE_IP_MREQN based on __FreeBSD_version
and OpenBSD version macros?

I generally prefer to keep old system compatibility code for ~ 5 years,
although it makes more sense on Linux, where are some LTS distributions
with similar long-term commitments, than on BSD.

-- 
Elen sila lumenn' omentielvo

Ondrej 'Santiago' Zajicek (email: santiago at crfreenet.org)
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"To err is human -- to blame it on a computer is even more so."