Re: [Doh] a tad confused on response sizes

Tony Finch <dot@dotat.at> Tue, 05 June 2018 14:14 UTC

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Date: Tue, 5 Jun 2018 15:13:56 +0100
From: Tony Finch <dot@dotat.at>
To: bert hubert <bert.hubert@powerdns.com>
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Subject: Re: [Doh] a tad confused on response sizes
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bert hubert <bert.hubert@powerdns.com>; wrote:
>
> This seems says sending a TC response is some kind of error, which implies
> a DNS API server should be willing to send 65 kilobyte answers.

Yes.

> I think for the new usecases, this would be a fine default. However, there
> might be UDP-to-DOH bridges which would then need to put explicit EDNS
> buffersize of 512 in there if they get non-EDNS adorned UDP queries.

If a UDP-to-DoH proxy gets an oversized answer it will have to do
its own truncation.

My trivial DoH code makes upstream queries over TCP, so the EDNS buffer
size is ignored. I don't think a DoH server should have to truncate
answers.

Tony.
-- 
f.anthony.n.finch  <dot@dotat.at>;  http://dotat.at/
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