Re: [Stox] I-D Action: draft-ietf-stox-7248bis-09.txt

Peter Saint-Andre <stpeter@stpeter.im> Tue, 30 August 2016 03:43 UTC

Return-Path: <stpeter@stpeter.im>
X-Original-To: stox@ietfa.amsl.com
Delivered-To: stox@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id C929E12D0E1 for <stox@ietfa.amsl.com>; Mon, 29 Aug 2016 20:43:22 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.45
X-Spam-Level:
X-Spam-Status: No, score=-2.45 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RP_MATCHES_RCVD=-0.548, SPF_HELO_PASS=-0.001, 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 KQiOhPJW8LnH for <stox@ietfa.amsl.com>; Mon, 29 Aug 2016 20:43:21 -0700 (PDT)
Received: from stpeter.im (mailhost.stpeter.im [207.210.219.225]) by ietfa.amsl.com (Postfix) with ESMTP id 9EF88127A90 for <stox@ietf.org>; Mon, 29 Aug 2016 20:43:21 -0700 (PDT)
Received: from aither.local (unknown [73.34.202.214]) (Authenticated sender: stpeter) by stpeter.im (Postfix) with ESMTPSA id DC200F075D; Mon, 29 Aug 2016 21:46:00 -0600 (MDT)
To: Ben Campbell <ben@nostrum.com>
References: <147241625250.24476.13333521107304467910.idtracker@ietfa.amsl.com> <a139f13c-9745-0d86-853b-d5d6b8c9124c@stpeter.im> <E1C65C7E-CDFF-40BC-AF01-B2F029B64E6E@nostrum.com>
From: Peter Saint-Andre <stpeter@stpeter.im>
Message-ID: <931fcd90-11c8-0b58-b3ad-eb6e7be2557e@stpeter.im>
Date: Mon, 29 Aug 2016 21:43:19 -0600
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:45.0) Gecko/20100101 Thunderbird/45.2.0
MIME-Version: 1.0
In-Reply-To: <E1C65C7E-CDFF-40BC-AF01-B2F029B64E6E@nostrum.com>
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding: 7bit
Archived-At: <https://mailarchive.ietf.org/arch/msg/stox/s0KXAt5RxvaBtpfe9uDooptXp0E>
Cc: stox@ietf.org
Subject: Re: [Stox] I-D Action: draft-ietf-stox-7248bis-09.txt
X-BeenThere: stox@ietf.org
X-Mailman-Version: 2.1.17
Precedence: list
List-Id: SIP-TO-XMPP Working Group discussion list <stox.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/stox>, <mailto:stox-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/stox/>
List-Post: <mailto:stox@ietf.org>
List-Help: <mailto:stox-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/stox>, <mailto:stox-request@ietf.org?subject=subscribe>
X-List-Received-Date: Tue, 30 Aug 2016 03:43:23 -0000

On 8/29/16 4:56 PM, Ben Campbell wrote:
> Hi Peter,
>
> I'm going to try to be more responsive on this, and break the apology
> loop :-)

Likewise!

> I agree we are zeroing in on things here. I think, with this version, I
> can better clarify my remaining concern. (I think it's the only thing
> left.)
>
> 5.2.3 talks about canceling a presence authorization. But from Romeo's
> perspective, it does do that; it only cancels the notification session.
> SIP has no way for Juliet to explicitly say "I want my permission to see
> Romeo's presence info to go away". If Juliet never wants to be notified
> again, she simply doesn't subscribe again. Maybe Romeo's system has some
> policy that ages out such authorizations over time, but that's not
> really relevant to this draft. (It's also possible for Romeo to
> unilaterally cancel that authorization, but that's probably more detail
> than is needed here.) In simpler terms, Romeo's presence server asks him
> if he wants to let Juliet subscribe the first time she tries. For future
> subscriptions, it won't ask. If Romeo later decides he prefers less
> star-crossed relationships, he can withdraw that permission. Other than
> than the initial subscription request, Juliet has no say in the matter.
>
> This is also true for _requesting_ authorization. For example, the only
> thing that makes 5.2.1 into a request for authorization (on the SIP
> side) is the fact that Juliet is subscribing for the first time. (I'm
> not saying 5.2.1 needs to change; I just mention this for background).
>
> Likewise in 5.3.3, Romeo is not asking to be deauthorized. He's just
> asking to end the notification session. Now that may not matter, he just
> gets re-authorized next time hie sends a SUBSCRIBE request. But he might
> be surprised to find that Juliet thought he had requested to be
> deauthorized. (Not to mention, that Juliet might feel, well,
> "unfriended" :-)  )
>
> This all goes counter to the statement in the 2nd to last paragraph of
> 5.1 that SIP presence authorizations are managed with SUBSCRIBE
> requests. The real situation is that the watcher (Juliet) doesn't manage
> these authorizations at all--they are unilaterally managed by the
> presentity (Romeo). A SUBSCRIBE request from Juliet may cause Romeo to
> be notified that he needs to make an authorization decision if he has
> not previously given permission.

Your description really clarified things for me, so thanks!

> So, how to fix this? I'm not sure I have the answer. But one approach
> might be to extend 5.1 to be more clear about the difference in
> authorization models, then have sections 5.2.x and 5.3.x talk more about
> notification sessions than authorization, but mention authorization
> state changes in the commentary about the message detail as needed.

Yes, that seems sensible. I will work on an updated I-D along those 
lines very soon.

Peter