[net-dns-users] SVCB

[Dick Franks]

On Mon, 11 Nov 2024 at 18:24, Doug Barton via net-dns-users
<net-dns-users at lists.nlnetlabs.nl> wrote:
>8
>
> On 2024-11-10 10:43 AM, Dick Franks via net-dns-users wrote:
> > On Sun, 10 Nov 2024 at 02:36, Doug Barton via net-dns-users
> > <net-dns-users at lists.nlnetlabs.nl> wrote:
> >>
> >> I have two questions about the SVCB/HTTPS implementation.
> >>
> >> First, how does one decode the "presentation format" data that's
> >> returned by the svcparam methods? I tried every combination of unpack
> >> that I could think of, including those used for pack and unpack in the
> >> pm file, and all I get is gibberish. None of the standard RR methods
> >> work either, including print, string, etc.; and I'm pretty sure I tried
> >> them all.

That is a reasonable complaint, which you did not follow through.
An uninterpreted octet string would be much easier to unpack.

>8
> > There is no credible use-case which involves resurrection of the
> > mnemonic presentation format from the wire-format representation.
>
> Of course there are. Why would these records be any different from all
> the other DNS records?
>
> My particular use case is that I have a Perl tool which does queries for
> common host names and record types to help evaluate the status of the
> zones for the domain names I manage.

If you manage the domains, your mnemonic SVCB RRs are present in a
zone file or database, which underlines my point that there is no
rationale for resurrecting mnemonic SVCBs from wireformat.

If SVCB comes from somewhere else, then the zone manager is someone else.

>8
> >> Second, what's the rationale for this substitution on line 190 of the
> >> current version of SVCB.pm:
> >>
> >>           return ( $target eq '.' ) ? $self->owner : $target;
> >>
> >
> > RFC9460(2.5.2)
>
> Yes, I know how the mechanism works, but I'm asking why you're forcing
> the substitution in the output.

Because RFC9460 says how the targetname should be derived when '.'
appears on the wire.

>
> More generally, is there a way to convert the presentation format back
> to mnemonic format?

Not without 60% more code nor serving any real purpose.

--rwf




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