[PATCH 3/5] resolv: Remove incorrect parts of TSIG handling from ns_sprintrrf (CVE-2026-5435)

[Florian Weimer]

* Adhemerval Zanella Netto:

> On 30/04/26 07:52, Florian Weimer wrote:
>> TSIG handling was incomplete before.  Given that this is an obsolete
>> interface, it does not seem worthwhile to complete the implementation.
>
> Wouldn't be better to make it fall for the default handler instead
> ("unknown RR type %d") instead?

I probably should make the unknown type RR handling RFC-compliant (see
RFC 3597).  For TSIG, there wouldn't be data loss because the embedded
domain name must not use label compression.  (With compression, you
wouldn't be able to recover the original name just from the hexdump.)

Thanks,
Florian