Re: [DNSOP] Clarification question: compression pointers always to names earlier in the packet?

Mark Andrews <marka@isc.org> Wed, 24 October 2018 20:10 UTC

Return-Path: <marka@isc.org>
X-Original-To: dnsop@ietfa.amsl.com
Delivered-To: dnsop@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id B8564124C04 for <dnsop@ietfa.amsl.com>; Wed, 24 Oct 2018 13:10:21 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -6.901
X-Spam-Level:
X-Spam-Status: No, score=-6.901 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RCVD_IN_DNSWL_HI=-5, SPF_PASS=-0.001] 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 2-85kNzMIEjP for <dnsop@ietfa.amsl.com>; Wed, 24 Oct 2018 13:10:20 -0700 (PDT)
Received: from mx.pao1.isc.org (mx.pao1.isc.org [IPv6:2001:4f8:0:2::2b]) (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 F20A3124BE5 for <dnsop@ietf.org>; Wed, 24 Oct 2018 13:10:19 -0700 (PDT)
Received: from zmx1.isc.org (zmx1.isc.org [149.20.0.20]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx.pao1.isc.org (Postfix) with ESMTPS id 557F23AB003; Wed, 24 Oct 2018 20:10:18 +0000 (UTC)
Received: from zmx1.isc.org (localhost [127.0.0.1]) by zmx1.isc.org (Postfix) with ESMTPS id 16EAA160041; Wed, 24 Oct 2018 20:10:18 +0000 (UTC)
Received: from localhost (localhost [127.0.0.1]) by zmx1.isc.org (Postfix) with ESMTP id 058A1160068; Wed, 24 Oct 2018 20:10:18 +0000 (UTC)
Received: from zmx1.isc.org ([127.0.0.1]) by localhost (zmx1.isc.org [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id LjMiogZ2OL_4; Wed, 24 Oct 2018 20:10:17 +0000 (UTC)
Received: from beetledviscorg9.home.lan (c27-253-115-14.carlnfd2.nsw.optusnet.com.au [27.253.115.14]) by zmx1.isc.org (Postfix) with ESMTPSA id 03FE3160041; Wed, 24 Oct 2018 20:10:16 +0000 (UTC)
Content-Type: text/plain; charset=us-ascii
Mime-Version: 1.0 (Mac OS X Mail 11.5 \(3445.9.1\))
From: Mark Andrews <marka@isc.org>
In-Reply-To: <CAPt1N1=r2fMs8UJh9eM6BZHYXEwJgYzKDVqs5J7MZhS1n5Zx6A@mail.gmail.com>
Date: Thu, 25 Oct 2018 07:10:14 +1100
Cc: martin@opennetlabs.com, Tony Finch <dot@dotat.at>, dnsop WG <dnsop@ietf.org>
Content-Transfer-Encoding: quoted-printable
Message-Id: <19CF1DF3-7EB3-470D-B64D-17694D0A5F25@isc.org>
References: <BC2CDF40-4FF0-4111-88B7-04969491D2E0@dukhovni.org> <alpine.DEB.2.20.1810241135130.24450@grey.csi.cam.ac.uk> <20181024124831.610d7521@glaurung.nlnetlabs.nl> <CAPt1N1=r2fMs8UJh9eM6BZHYXEwJgYzKDVqs5J7MZhS1n5Zx6A@mail.gmail.com>
To: Ted Lemon <mellon@fugue.com>
X-Mailer: Apple Mail (2.3445.9.1)
Archived-At: <https://mailarchive.ietf.org/arch/msg/dnsop/qQkCPEYKoWYCswFAEv5xjz-kXBI>
Subject: Re: [DNSOP] Clarification question: compression pointers always to names earlier in the packet?
X-BeenThere: dnsop@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: IETF DNSOP WG mailing list <dnsop.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/dnsop>, <mailto:dnsop-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/dnsop/>
List-Post: <mailto:dnsop@ietf.org>
List-Help: <mailto:dnsop-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/dnsop>, <mailto:dnsop-request@ietf.org?subject=subscribe>
X-List-Received-Date: Wed, 24 Oct 2018 20:10:22 -0000

No.

> On 25 Oct 2018, at 6:52 am, Ted Lemon <mellon@fugue.com> wrote:
> 
> Is there ever a valid reason to have a pointer to a pointer, though?   This is dead easy to detect.
> 
> On Wed, Oct 24, 2018 at 6:48 AM Martin Hoffmann <martin@opennetlabs.com> wrote:
> Tony Finch wrote:
> > 
> > Note that limiting the overall length of the name isn't enough,
> > because a pointer can loop without making the name longer.
> 
> You are, of course, right.
> 
> Kind regards,
> Martin
> 
> _______________________________________________
> DNSOP mailing list
> DNSOP@ietf.org
> https://www.ietf.org/mailman/listinfo/dnsop
> _______________________________________________
> DNSOP mailing list
> DNSOP@ietf.org
> https://www.ietf.org/mailman/listinfo/dnsop

-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742              INTERNET: marka@isc.org