Re: [musl] Resolver routines, Postfix DNSSEC troubles - how to check for incompatibilities?

[Christian <list-christian@web.de>]

Am Montag, den 13.04.2020, 12:38 -0400 schrieb Rich Felker:
> On Mon, Apr 13, 2020 at 05:52:34PM +0200, Florian Weimer wrote:
>
> * Christian:
>
>
> So Viktor did some digging:
>
> "The comment on line 25:
>
>
https://github.com/runtimejs/musl-libc/blob/master/include/resolv.h#L25
>
> is not encouraging.  It suggests that _res is unused. If so, Postfix
> DNS does not work correctly with this C library.  And not just for
> DANE, since Postfix is also unable to to control RES_DEFNAMES and
> RES_DNSRCH.
>
> Are these changes to the RES_DEFNAMES and RES_DNSRCH flags really
> necessary? Why doesn't Postfix use res_query (or perhaps res_send) as
> appropriate?
>
> But to actually answer these questions, modifying the flags is
> presumably because traditional req_query builds an rfc1035 query or
> edns query based on these flags derived from from resolv.conf, and
> Postfix either assumes or wants to support the case where resolv.conf
> is not already configured for edns, perhaps because it was generated
> by a dhcp client.
>
> Rich
>
>

I can't tell you much on the coding or why it is this way. I am merely
a user that found the incompatibility. If this is of interest, you
might want to get in contact with Viktor, e.g. via the postfix users
mailing list.

FYI: I just moved my config to a glibc setup in debian and it is
working without issues, hence confirming Viktors finding, that Postfix
won't work with musl