Re: [PATCH] dns: store priv->last_iface even when no actual updates are performed

[Michael Stapelberg <michael+nm stapelberg de>]

Hi Dan,

Dan Williams <dcbw redhat com> writes:
> Sending the interface name is a hack anyway just to make netconfig and
> resolvconf happy, even though prioritizing DNS information based on
> interface name is bogus.  NM merges and prioritizes the DNS
> configuration before sending to resolvconf/netconfig, so whatever
> interface we happen to send to them is already quite wrong, since the
> data may come from multiple interfaces.
>
> Instead, we should rip out all the interface name stuff and simply send
> "NetworkManager".  Then people can do whatever they want with NM's data
> in the resolvconf priority, and I have no idea what netconfig does with
> INTERFACE=xxx but it's still going to be wrong, whatever it is.
>
> (you simply can't prioritize DNS data based on interface names, because
> interfaces service many different networks.  Sometimes your eth0 is
> connected to a lower-priority network than your wlan0, sometimes it's
> higher.  That is a *per-network* decision, not a per-interface one, but
> netconfig/resolvconf still seem to think it's per-interface...)
This might be correct for the case you have in mind.

However, note that I was talking about interface-specific nameserver
addresses (link-local IPv6), e.g. fe80::4e60:deff:fed8:d7c5%wlan0. Since
it is that code path in which the segfault is triggered, we clearly need
to send the _correct_ interface, not just âNetworkManagerâ, otherwise we
will end up with server=fe80::4e60:deff:fed8:d7c5%NetworkManager in the
dnsmasq config :-).

-- 
Best regards,
Michael