[systemd-devel] [PATCH] resolved: re-add support for getting local domain from DHCP

[Lennart Poettering]

On Thu, 14.08.14 02:21, Lennart Poettering (lennart at poettering.net) wrote:

> On Mon, 04.08.14 10:05, Michael Marineau (michael.marineau at coreos.com) wrote:
> 
> Patch looks pretty good, though I'd really prefer if we could do the
> UseDomain= thing as discussed in the other mail, and not propagate
> DHCP-supplied domain names unless explicitly requested.
> 
> This would means we probably mean we'd need two new sd-network.h calls:
> 
> int sd_network_get_link_route_domains(int ifindex, char **domains);
> int sd_network_get_link_search_domains(int ifindex, char **domains);
> 
> The former would return the list of domains whose requests shall be
> routed to the specified interface, and the latter would be the list of
> domains we actively use for searching single-label domains in.
> 
> Any domains configured statically for a link in the .network files would
> be listed in both lists. And depending on the UseDomains= settings the
> dhcp provides domains might be listed on none, both or only one of
> them. or something like that...

So, I have thought about this a bit more over night... I think this
would still be too complicated, and I don't really see the need to make
the dhcp search thing that configurable. I see no risk in strictly
making single-label host names searchable in all configured domains of
the interface and nothing else...

I think I am back at suggesting that there should be the follow .network settings:

   [Network]
   Domains=0pointer.de redhat.com

   [DHCP]
   UseDomains=yes|no

And one sd-network function:

   int sd_network_get_link_domains(int ifindex, char **domains);

And that should be it.

UseDomain= should have the effect of adding the domains from dhcp option
15 and 119 to the list of domains for the interface. And
sd_network_get_link_domains() should then return a single list, of
deduplicated entries, with the domains specified in Domains= first, and
then the dhcp domains possible added in at the end.

Zbigniew, I think this simplification would be beneficial, as I really
don't see the need to make the search vs. route domain thing
configurable....

Tom, what's your take on all of this?

The domain data from DHCP should be thoroughly verified btw. For
example, if is_hostname() is true for some domain acquired via DHCP we
should ignore it, and we should make sure that the domain name is
actually valid, and so on.

Lennart

-- 
Lennart Poettering, Red Hat