[net-dns-users] SVCB

[Doug Barton]

Thanks for your response. Some comments and questions below.

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.
> 
> SVCB RRs are intended to be interpreted by browsers and similar
> software elements.

As are all other DNS records.

> The mnemonic presentation format described in RFC9460 facilitates
> construction of SVCB RRs in zone files.
> Subsequent representation of the SVCB RRs so constructed uses RFC3597 format.
> 
> 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. I'd like to be able to continue to 
use this tool with SVCB and HTTPS records included, rather than 
resorting to doing a dig, which does show the mnemonic format (just like 
dig does for all the other DNS records).

What's the rationale for making these two an exception to the general rule?

>> 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.

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

Doug