[Dnsmasq-discuss] Failure of dnsmasq v2.81 in docker (qemu emulated armhf hardware)

[Dominik]

Hey Simon,

we've observed that since
http://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commitdiff;h=1627d577af03cdf747285e79fa747b6aaae8033f
dnsmasq wouldn't build any longer in our docker environment.

Even when your further commit
http://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=0506a5ed4e56863627c54aedad30ad61221292ef
restored the compilation, we did now realize that dnsmasq still doesn't
work!

In dnsmasq v2.81, the added setsockopt() is always called and dnsmasq
dies hard when it fails.

This is exactly what is happening inside our docker container:

> Unsupported setsockopt level=270 optname=5
>
> dnsmasq: cannot create netlink socket: Protocol not available
>

A possible solution seems to be what Petr Gotthard suggested
(dnsmasq-discuss /Thu Mar 19 13:16:11 GMT 2020/):

> +#ifdef NETLINK_NO_ENOBUFS
>        setsockopt(daemon->netlinkfd, SOL_NETLINK, NETLINK_NO_ENOBUFS, &opt, sizeof(opt)) == -1 ||
> +#endif

Best regards,
Dominik