[net-dns-users] SVCB

[Dick Franks]

On Thu, 21 Nov 2024 at 17:52, Doug Barton via net-dns-users <
net-dns-users at lists.nlnetlabs.nl> wrote:
>8

> >>>> 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.
>
> Can you please elaborate on this? I'm not sure what you mean here. Is
> there something else you need from me to demonstrate the issue?
>
The issue here is that a RFC1035 character string containing a large
proportion of non-printable characters is nigh on incomprehensible to the
average human. Extracting the octet string takes significant effort.

I will pursue that topic in RT.cpan.org #157043.

>
 >>>> 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.
>
> The RFC describes how the information should be used, not how it should
> be displayed in text. I still think that at least having a mnemonic
> display option here would be useful.


 my $svcb = Net::DNS::RR->new( <<'END' );
 example.com.    SVCB    1 .  ipv6hint=2001:db8::1
 END

 $svcb->print;

 example.com.    IN      SVCB    ( \# 23 0001 00 ; .     <--- displayed in
text
        0006 0010 20010db8000000000000000000000001 )

 print $svcb->targetname;        <--- used in application

.example.com


>
> >> 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.
>
> I hope I've described my need for this adequately above.
>
> If you could point me in the right direction in terms of the conversion
> I'd be willing to work on a patch. At minimum I need to do this for my
> own purposes, so any tips would be very much appreciated.

What you are asking for is way beyond casual patching.

Ask yourself, would you be prepared to pay $5000 to make this happen?

if so, please send me $5000.
If not, why am I going to waste $5000 of my effort to satisfy a "need"
which is, at best, marginal?
.
--rwf
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