Re: [Doh] [Ext] Proposal to close off these threads

Tony Finch <dot@dotat.at> Mon, 11 June 2018 15:54 UTC

Return-Path: <dot@dotat.at>
X-Original-To: doh@ietfa.amsl.com
Delivered-To: doh@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 6787E130E5F for <doh@ietfa.amsl.com>; Mon, 11 Jun 2018 08:54:24 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -4.2
X-Spam-Level:
X-Spam-Status: No, score=-4.2 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3] autolearn=ham autolearn_force=no
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id dPm81_pgVxKW for <doh@ietfa.amsl.com>; Mon, 11 Jun 2018 08:54:22 -0700 (PDT)
Received: from ppsw-32.csi.cam.ac.uk (ppsw-32.csi.cam.ac.uk [131.111.8.132]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 0D796130E3B for <doh@ietf.org>; Mon, 11 Jun 2018 08:54:22 -0700 (PDT)
X-Cam-AntiVirus: no malware found
X-Cam-ScannerInfo: http://help.uis.cam.ac.uk/email-scanner-virus
Received: from grey.csi.cam.ac.uk ([131.111.57.57]:45172) by ppsw-32.csi.cam.ac.uk (ppsw.cam.ac.uk [131.111.8.138]:25) with esmtps (TLSv1:ECDHE-RSA-AES256-SHA:256) id 1fSP98-000giZ-2Z (Exim 4.91) (return-path <dot@dotat.at>); Mon, 11 Jun 2018 16:54:18 +0100
Date: Mon, 11 Jun 2018 16:54:18 +0100
From: Tony Finch <dot@dotat.at>
To: Patrick McManus <pmcmanus@mozilla.com>
cc: Paul Hoffman <paul.hoffman@icann.org>, DoH WG <doh@ietf.org>
In-Reply-To: <CAOdDvNoYYVEGC0Zsyd1m8sayuzZoW186gb4gmMojZzvYy6=6rw@mail.gmail.com>
Message-ID: <alpine.DEB.2.11.1806111648580.10764@grey.csi.cam.ac.uk>
References: <1D917C05-2B74-4607-9EE2-55D367FF48B5@icann.org> <20180610220841.GB16671@server.ds9a.nl> <CAOdDvNrXpyGTFmMHcF6Vnegku0Zmiw_LFb1VKm1O2mFgB3aHEw@mail.gmail.com> <FB8DBC78-4584-4133-AF1F-E0483C28224D@icann.org> <CAOdDvNoYYVEGC0Zsyd1m8sayuzZoW186gb4gmMojZzvYy6=6rw@mail.gmail.com>
User-Agent: Alpine 2.11 (DEB 23 2013-08-11)
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset="US-ASCII"
Archived-At: <https://mailarchive.ietf.org/arch/msg/doh/kfoaAk7Uogv3eNjFMdtX_-J-MAc>
Subject: Re: [Doh] [Ext] Proposal to close off these threads
X-BeenThere: doh@ietf.org
X-Mailman-Version: 2.1.26
Precedence: list
List-Id: DNS Over HTTPS <doh.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/doh>, <mailto:doh-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/doh/>
List-Post: <mailto:doh@ietf.org>
List-Help: <mailto:doh-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/doh>, <mailto:doh-request@ietf.org?subject=subscribe>
X-List-Received-Date: Mon, 11 Jun 2018 15:54:24 -0000

Patrick McManus <pmcmanus@mozilla.com> wrote:
>
> There has a been a convincing case that a > 64KB axfr responses uses 2
> wireformat records in TCP today and therefore won't fit in the DoH MTI
> wireformat media type. AIUI that's not because its AXFR, but because it is
> >64KB, right? At the same time tale convincingly argues he has plenty of
> <64KB zones that only use one message and match our MTI fine.

It's more complicated than that :-)

Small zones can be transferred using multiple messages too.

A DoH proxy might be able to defragment a small multi-message transfer,
provided there isn't any TSIG authentication.

Large zones with more than 64K records must use multiple messages, not
because of the 2 byte message size, but because of the 2 byte ANCOUNT.

> "HTTP defines status code 406 for cases where the server cannot generate a
> representation suitable for the client". We can probably just say that.

My DoH server sends a 200 OK HTTP response containing a NOTIMP DNS response.

Tony.
-- 
f.anthony.n.finch  <dot@dotat.at>  http://dotat.at/
Bailey, Fair Isle, Faeroes: West or northwest 3 or 4, increasing 5 at times in
Fair Isle. Slight or moderate. Rain at times. Good, occasionally moderate.