Re: c-ares: Adding new lookup types to config_lookup

On Tue, Aug 19, 2008 at 11:16:23PM +0200, Daniel Stenberg wrote:
> I'm not even 100% sure I think other protocols than pure DNS is what we
> want in c-ares. What exactly whould be the benefit of this?

The benefit of lwres specifically, or generally protocols other
than pure DNS? I think the "in general" is important on systems
with the Gnu C library's resolver; on them the standard
gethostbyname() transparently handles the "in general" by using
whatever is configured in /etc/nsswitch.

Currently lwres probably doesn't add much, as the lwres daemon
forwards the requests as DNS requests.

However, the current libc-ares fails rather than falling back to
DNS if /etc/nsswitch.conf contains
  hosts: files lwres

I think mDNS would be more beneficial, to prevent this scenario:
  Browse an HTTP server on the local network, using a browser that
  uses the stardard C library's resolver. That resolver
  transparently handles all of DNS, mDNS and lwres.

  The browser launches an application that uses libc-ares, giving
  it the URL.

  The libc-ares based application ignores the mDNS option in
  /etc/resolve.conf, and fails.

In Debian, both Gnome and KDE are recommending installing mDNS
support, and it's installed on 57% of PCs that contribute to their
package popularity stats.
  http://qa.debian.org/popcon.php?package=avahi

The patch attached to my previous mail should help any of lwres,
mDNS or just (recognise the lwres option, and fall back to DNS).

Steve
Received on 2008-08-25