Re: [DNSOP] Perl related question on BULK RR

"Woodworth, John R" <John.Woodworth@CenturyLink.com> Tue, 28 March 2017 16:24 UTC

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From: "Woodworth, John R" <John.Woodworth@CenturyLink.com>
To: "'Tony Finch'" <dot@dotat.at>
CC: "'dnsop@ietf.org'" <dnsop@ietf.org>, "Ballew, Dean" <Dean.Ballew@CenturyLink.com>, "'JW'" <jw@pcthink.com>, "Woodworth, John R" <John.Woodworth@CenturyLink.com>
Thread-Topic: [DNSOP] Perl related question on BULK RR
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Date: Tue, 28 Mar 2017 16:24:03 +0000
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Subject: Re: [DNSOP] Perl related question on BULK RR
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> -----Original Message-----
> From: DNSOP [mailto:dnsop-bounces@ietf.org] On Behalf Of Tony Finch
>
> Woodworth, John R <John.Woodworth@CenturyLink.com> wrote:
>
> > Apologies but I did not hear the full question regarding BULK RR's and
> > the perl like back-references.  If you could please repeat the
> > question we would be happy to comment.
>
> I didn't ask the question, but based on a quick look at the draft I
> think there might be a fun problem.
>
> Frequently, when you have string rewriting with substitution and
> iteration, you have a Turing-complete esoteric programming system.
>
> NAPTR very cunningly avoids this trap (IIRC) by constraining the
> rewrites to be on a strictly monotonically reducing suffix of the
> input.
>
> BULK does not itself have built-in iteration like NAPTR, but because
> it synthesizes records it interacts with the DNS's existing resolver
> loops:
> chasing delegations, and chasing CNAMEs and DNAMEs. Note that CNAMEs
> and DNAMEs are also chased within authoritative servers.
>
> So my question is, how does the BULK rewriting system interact with
> DNS loops? Is there a CPU-eating tarpit in there?
>
Hi Tony,

Thank you for the excellent question.  I will need to run through some
logic exercises to attempt to create this scenario and if successful
work out a solution.


Thanks,
John
>
> Tony.
> --
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