Bug#895981: please cleanup /var/cache/nscd on restart

["Carlos O'Donell" <carlos@systemhalted.org>]

On Sun, Apr 29, 2018 at 2:56 PM, Florian Weimer <fw@deneb.enyo.de> wrote:

* Harald Dunkel:

> I am using both systemd and sysvinit-core, but I am not sure which one
> was active when I ran into this problem.
>
> Consider a split DNS setup for a remote network. I had started an IPsec
> connection to the remote side. /etc/resolv.conf was changed to include
> the new internal DNServer on the remote side, but a host lookup gave me
> still the old external address. Stopping nscd did not help, AFAIR.

That's arguably a bug in nscd.  It should flush the cache each time it
detects a change in /etc/resolv.conf (or /etc/gai.conf, for that
matter).

 And it does, this is what define_traced_file/init_traced_file do in nss/nss_files/files-init.c.

Then via the nscd callback nscd_init_cb, we call register_traced_file for each loaded database.

Then each registered file, like /etc/resolv.conf, is watched via inotify for any changes, and if

a change is detected and finfo->call_res_init was true (and it's true only for resolv.conf) then

we call res_init().

We do not handle anything for changes in gai.conf, we would have to add that.

Cheers,

Carlos.