Re: [musl] [BUG] Non-FQDN domain resolving failure on musl-1.2.x

[Jeffrey Walton <noloader@gmail.com>]

On Fri, Jun 24, 2022 at 10:59 AM Rich Felker <dalias@libc.org> wrote:
>
> On Fri, Jun 24, 2022 at 12:28:24PM +0200, Markus Geiger wrote:
> > Hej!
> >
> > First, I love MUSL (and alpine linux). Great project!
> >
> > We encountered a bug in our CI pipeline using alpine images in conjunction
> > with AWS DNS servers - and it seems to be related to MUSL:
> >
> > $ curl -fsSL https://slack.com
> > curl: (6) Could not resolve host: slack.com
> >
> > Usually that should return some HTML. It seems to affect only non-FQDN
> > domains. As a workaround we use now full FQDN api.slack.com. But there is a
> > bug in resolvement! It seems if an AAAA domain is queried over an IPV4
> > IP/DNS and doesn’t not return a record the overall resolvement of the
> > domain fails.
>
> That's not non-FQDN. Non-FQDN would be "api" as short for
> api.slack.com. slack.com is just the apex of a zone, but there's
> nothing special about that for resolving; it's likely just a
> difference in the records for it vs api, or something fishy the
> recursive nameserver you're using is doing...

+1.

A FQDN ends in '.' (dot). The dot specifies the root of the DNS tree.
'slack.com.' is fully qualified, but 'slack.com' is not. If you are
configured to search with domain suffixes, 'slack.com' could resolve
to 'slack.com.home.pvt' because it is not fully qualified.

Jeff