Re: p1: handling obs-fold
Mark Nottingham <mnot@mnot.net> Sat, 20 April 2013 07:44 UTC
Return-Path: <ietf-http-wg-request@listhub.w3.org>
X-Original-To: ietfarch-httpbisa-archive-bis2Juki@ietfa.amsl.com
Delivered-To: ietfarch-httpbisa-archive-bis2Juki@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 4424E21F881F for <ietfarch-httpbisa-archive-bis2Juki@ietfa.amsl.com>; Sat, 20 Apr 2013 00:44:03 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -10.527
X-Spam-Level:
X-Spam-Status: No, score=-10.527 tagged_above=-999 required=5 tests=[AWL=0.072, BAYES_00=-2.599, RCVD_IN_DNSWL_HI=-8]
Received: from mail.ietf.org ([12.22.58.30]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 2IExJvRw44br for <ietfarch-httpbisa-archive-bis2Juki@ietfa.amsl.com>; Sat, 20 Apr 2013 00:44:02 -0700 (PDT)
Received: from frink.w3.org (frink.w3.org [128.30.52.56]) by ietfa.amsl.com (Postfix) with ESMTP id 7029721F8759 for <httpbisa-archive-bis2Juki@lists.ietf.org>; Sat, 20 Apr 2013 00:44:02 -0700 (PDT)
Received: from lists by frink.w3.org with local (Exim 4.72) (envelope-from <ietf-http-wg-request@listhub.w3.org>) id 1UTSSa-0004IS-5L for ietf-http-wg-dist@listhub.w3.org; Sat, 20 Apr 2013 07:43:48 +0000
Resent-Date: Sat, 20 Apr 2013 07:43:48 +0000
Resent-Message-Id: <E1UTSSa-0004IS-5L@frink.w3.org>
Received: from lisa.w3.org ([128.30.52.41]) by frink.w3.org with esmtp (Exim 4.72) (envelope-from <mnot@mnot.net>) id 1UTSSW-0004EO-Oe for ietf-http-wg@listhub.w3.org; Sat, 20 Apr 2013 07:43:44 +0000
Received: from mxout-08.mxes.net ([216.86.168.183]) by lisa.w3.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.72) (envelope-from <mnot@mnot.net>) id 1UTSSW-0005j1-8D for ietf-http-wg@w3.org; Sat, 20 Apr 2013 07:43:44 +0000
Received: from [192.168.1.80] (unknown [118.209.190.66]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) by smtp.mxes.net (Postfix) with ESMTPSA id 4EE93509B8; Sat, 20 Apr 2013 03:43:21 -0400 (EDT)
Content-Type: text/plain; charset="us-ascii"
Mime-Version: 1.0 (Mac OS X Mail 6.3 \(1503\))
From: Mark Nottingham <mnot@mnot.net>
In-Reply-To: <20130420070038.GG26517@1wt.eu>
Date: Sat, 20 Apr 2013 17:43:18 +1000
Cc: "ietf-http-wg@w3.org Group" <ietf-http-wg@w3.org>
Content-Transfer-Encoding: quoted-printable
Message-Id: <678BD72B-3E8D-46B0-852F-F7428958BD68@mnot.net>
References: <2118F2B3-643F-4D2E-85E9-60988EF6C839@mnot.net> <20130420070038.GG26517@1wt.eu>
To: Willy Tarreau <w@1wt.eu>
X-Mailer: Apple Mail (2.1503)
Received-SPF: pass client-ip=216.86.168.183; envelope-from=mnot@mnot.net; helo=mxout-08.mxes.net
X-W3C-Hub-Spam-Status: No, score=-3.4
X-W3C-Hub-Spam-Report: AWL=-3.352, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001
X-W3C-Scan-Sig: lisa.w3.org 1UTSSW-0005j1-8D 12c2ba24182af82baa837294bad03a2c
X-Original-To: ietf-http-wg@w3.org
Subject: Re: p1: handling obs-fold
Archived-At: <http://www.w3.org/mid/678BD72B-3E8D-46B0-852F-F7428958BD68@mnot.net>
Resent-From: ietf-http-wg@w3.org
X-Mailing-List: <ietf-http-wg@w3.org> archive/latest/17401
X-Loop: ietf-http-wg@w3.org
Resent-Sender: ietf-http-wg-request@w3.org
Precedence: list
List-Id: <ietf-http-wg.w3.org>
List-Help: <http://www.w3.org/Mail/>
List-Post: <mailto:ietf-http-wg@w3.org>
List-Unsubscribe: <mailto:ietf-http-wg-request@w3.org?subject=unsubscribe>
On 20/04/2013, at 5:00 PM, Willy Tarreau <w@1wt.eu> wrote: > On Sat, Apr 20, 2013 at 02:07:39PM +1000, Mark Nottingham wrote: >> p1 3.2.4 defines requirements for handling obs-fold: >> >>> When an obs-fold is received in a message, recipients MUST do one of: >>> >>> ? accept the message and replace any embedded obs-fold whitespace with either a single SP or a matching number of SP octets (to avoid buffer copying) prior to interpreting the field value or forwarding the message downstream; >>> ? if it is a request, reject the message by sending a 400 (Bad Request) response with a representation explaining that obsolete line folding is unacceptable; or, >>> ? if it is a response, discard the message and generate a 502 (Bad Gateway) response with a representation explaining that unacceptable line folding was received. >>> >>> Recipients that choose not to implement obs-fold processing (as described above) MUST NOT accept messages containing header fields with leading whitespace, as this can expose them to attacks that exploit this difference in processing. >> >> This seems to repeat itself; what is the difference between choosing to reject the request in the manner described in the last two bullet points, and not accepting the message? >> >> I think that the last sentence can be removed. > > I think it was here before the addition above. In fact it targets a different > audience which is not aware of OBS at all. The simple fact that we talk about > prepending spaces before a header field means that the reader doesn't > understand that this field is not one but the continuation of previous one. > > Maybe this confusing sentence should be removed and replaced with something > like this before the block you quoted : > > Presence of a space or tab character at the beginning of a line must not > be taken as a new header field but as the continuation of previous header > field (obs-fold). As such it cannot happen on the first header field. > > That way readers looking for what to do with these spaces will find their > response here and will be able to decide what to do with the options that > are offered to them. Seems reasonable; I think this one is largely editorial; the only way I'd be really concerned would be if nothing changed. Recorded as: http://trac.tools.ietf.org/wg/httpbis/trac/ticket/444 with suggestions. -- Mark Nottingham http://www.mnot.net/
- p1: handling obs-fold Mark Nottingham
- Re: p1: handling obs-fold Willy Tarreau
- Re: p1: handling obs-fold Mark Nottingham
- Re: p1: handling obs-fold Amos Jeffries
- Re: p1: handling obs-fold Roy T. Fielding