Bug#362029: [PATCH] Installer doesn't create resolv.conf

[Matthew Palmer <mpalmer@debian.org>]

tag 362029 +patch
thanks

The attached patch fixes netcfg to write a complete resolv.conf if the DHCP
server doesn't provide all of the necessary data for that file.  As
previously mentioned, the problem is that the DHCP configuration method
assumes that resolv.conf will *always* be written entirely by udhcpc.  This
patch writes out resolv.conf whenever netcfg asks for some piece of
resolv.conf-relevant information.

The complication is that if resolvers were configured by udhcpc, netcfg
*doesn't* *know* about that information, so if netcfg rewrites resolv.conf
the resolver info is lost.  So we need to read that data out of resolv.conf
before we rewrite it -- that's where half the code comes from in this patch.

I've tested the patch with a DHCP server that supplies:

* neither domain-name nor domain-name-servers,
* Just domain-name,
* Just domain-name-servers, and
* Both domain-name and domain-name-servers.

With this patch, all four of those cases result in a resolv.conf that
contains all of the information supplied via DHCP and relevant debconf
questions.

- Matt