Re: [Doh] [Ext] Re: Associating a DoH server with a resolver

Paul Hoffman <paul.hoffman@icann.org> Wed, 24 October 2018 01:12 UTC

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From: Paul Hoffman <paul.hoffman@icann.org>
To: Martin Thomson <martin.thomson@gmail.com>
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Thread-Topic: [Ext] Re: [Doh] Associating a DoH server with a resolver
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Date: Wed, 24 Oct 2018 01:12:09 +0000
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Subject: Re: [Doh] [Ext] Re: Associating a DoH server with a resolver
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On Oct 23, 2018, at 6:08 PM, Martin Thomson <martin.thomson@gmail.com> wrote:
> 
> Why do the IP-based spelunking?  It requires that the resolver (which
> might not be a DoH server) do HTTP as well.  Can't you define a record
> that could be placed at the resolver-addresses.arpa name?  I hesitate
> to say TXT, but I can't think of a good reason not to use that in this
> case.  Multiple such records could identify different DNS-over-foo
> variants.

Given the offline comments I'm getting similar to this one, I did not emphasize this enough in the draft.

There is no way for an application like a browser to send a query through the OS for anything other than address records. That is, gethostbyname() and its equivalents only pass back address records. Even if an application had its own DNS stack to make queries for other RRtypes, it doesn't have any way to know where to send them to.

If I'm wrong about the above, that's great, because we could certainly simplify the way that Martin suggests above or that I had in earlier versions of the draft.

--Paul Hoffman