Re: [PATCH] resolv.conf parser: concatenate multiple search domain lines

[Rich Felker <dalias@libc.org>]

On Fri, Mar 30, 2018 at 02:27:42PM +0200, Quentin Rameau wrote:
> Hi William,
> 
> > Programs such as Docker and Kubernetes write multiple domain search
> > lines, such as
> > 
> > search serious-business.big-data.prod.foo.com
> > search big-data.prod.foo.com
> > search prod.foo.com
> > 
> > instead of
> > 
> > search serious-business.big-data.prod.foo.com big-data.prod.foo.com
> > prod.foo.com
> > 
> > Accordingly, we concatenate the namelist together so that the search
> > path is not truncated.
> 
> I think this patch should be sent to Docker and Kubernetes instead of
> pushing a mitigation for their bug in the libc.
> 
> According to documentation, “The domain and search keywords are
> mutually exclusive.  If more than one instance of these keywords is
> present, the last instance wins.”
> 
> This patch would break existing applications relying on documented
> behaviour.

I wrote the current behavior based on that documentation. Apparently
the current glibc behavior does not match the documentation, but I'd
really rather not go against the documentation unless there's
agreement from glibc/others that the documentation is wrong and their
current behavior is desired. Either way I think Docker/Kubernetes
should fix this, since it's ambiguous what the "right" thing to do is
and there very well could end up being inconsistent behaviors between
libcs/versions into the future.

Rich