Re: [Doh] [Ext] a tad confused on response sizes

Stephane Bortzmeyer <bortzmeyer@nic.fr> Tue, 05 June 2018 15:23 UTC

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Date: Tue, 5 Jun 2018 17:23:55 +0200
From: Stephane Bortzmeyer <bortzmeyer@nic.fr>
To: Tony Finch <dot@dotat.at>
Cc: Paul Hoffman <paul.hoffman@icann.org>, "doh@ietf.org" <doh@ietf.org>
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References: <20180605120510.GA29047@server.ds9a.nl> <CFEAAD6E-4F9D-4DB5-A362-21775D74F84A@icann.org> <alpine.DEB.2.11.1806051515510.1809@grey.csi.cam.ac.uk> <663E7B21-9107-4A2B-9DEB-E13475A4E5FF@icann.org> <alpine.DEB.2.11.1806051604150.1809@grey.csi.cam.ac.uk>
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Subject: Re: [Doh] [Ext] a tad confused on response sizes
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On Tue, Jun 05, 2018 at 04:07:42PM +0100,
 Tony Finch <dot@dotat.at>; wrote 
 a message of 25 lines which said:

> No, TC means "I have more to tell you but it wouldn't fit in your buffer".

TC is supposed to be hop-to-hop but DoH makes things more complicated,
the HTTPS link having different semantics. For DoH, it means (I quote
the -10 draft) "I was not able to retrieve a full answer for the query
but I give you the best answer I could get"

PS : what happens when a DNS-over-TCP client receives a truncated
answer over TCP? It is technically possible and nobody expects RFC
7766 to address this point.