Re: The first octet

Christian Huitema <huitema@huitema.net> Mon, 06 August 2018 17:27 UTC

Return-Path: <huitema@huitema.net>
X-Original-To: quic@ietfa.amsl.com
Delivered-To: quic@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 660A7130EE8 for <quic@ietfa.amsl.com>; Mon, 6 Aug 2018 10:27:02 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.601
X-Spam-Level:
X-Spam-Status: No, score=-2.601 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RCVD_IN_DNSWL_LOW=-0.7, 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 p3nctlQb7vqH for <quic@ietfa.amsl.com>; Mon, 6 Aug 2018 10:26:54 -0700 (PDT)
Received: from mx43-out1.antispamcloud.com (mx43-out1.antispamcloud.com [138.201.61.189]) (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 76867130EE4 for <quic@ietf.org>; Mon, 6 Aug 2018 10:26:54 -0700 (PDT)
Received: from xsmtp31.mail2web.com ([168.144.250.234] helo=xsmtp11.mail2web.com) by mx114.antispamcloud.com with esmtps (TLSv1:AES256-SHA:256) (Exim 4.89) (envelope-from <huitema@huitema.net>) id 1fmjGx-000lbt-VS for quic@ietf.org; Mon, 06 Aug 2018 19:26:51 +0200
Received: from [10.5.2.12] (helo=xmail02.myhosting.com) by xsmtp11.mail2web.com with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.63) (envelope-from <huitema@huitema.net>) id 1fmjFv-0003YX-Qn for quic@ietf.org; Mon, 06 Aug 2018 13:26:22 -0400
Received: (qmail 11050 invoked from network); 6 Aug 2018 17:05:56 -0000
Received: from unknown (HELO [192.168.1.105]) (Authenticated-user:_huitema@huitema.net@[172.56.42.107]) (envelope-sender <huitema@huitema.net>) by xmail02.myhosting.com (qmail-ldap-1.03) with ESMTPA for <quic@ietf.org>; 6 Aug 2018 17:05:55 -0000
To: Martin Thomson <martin.thomson@gmail.com>, quic@ietf.org
References: <CABkgnnVFYMjWDk6zEEA8T_6qg+6qO9yAwVF70foMj4bXEdBaqQ@mail.gmail.com>
From: Christian Huitema <huitema@huitema.net>
Openpgp: preference=signencrypt
Autocrypt: addr=huitema@huitema.net; prefer-encrypt=mutual; keydata= xsBNBFIRX8gBCAC26usy/Ya38IqaLBSu33vKD6hP5Yw390XsWLaAZTeQR64OJEkoOdXpvcOS HWfMIlD5s5+oHfLe8jjmErFAXYJ8yytPj1fD2OdSKAe1TccUBiOXT8wdVxSr5d0alExVv/LO I/vA2aU1TwOkVHKSapD7j8/HZBrqIWRrXUSj2f5n9tY2nJzG9KRzSG0giaJWBfUFiGb4lvsy IaCaIU0YpfkDDk6PtK5YYzuCeF0B+O7N9LhDu/foUUc4MNq4K3EKDPb2FL1Hrv0XHpkXeMRZ olpH8SUFUJbmi+zYRuUgcXgMZRmZFL1tu6z9h6gY4/KPyF9aYot6zG28Qk/BFQRtj7V1ABEB AAHNJ0NocmlzdGlhbiBIdWl0ZW1hIDxodWl0ZW1hQGh1aXRlbWEubmV0PsLAeQQTAQIAIwUC UhFfyAIbLwcLCQgHAwIBBhUIAgkKCwQWAgMBAh4BAheAAAoJEJNDCbJVyA1yhbYH/1ud6x6m VqGIp0JcZUfSQO8w+TjugqxCyGNn+w/6Qb5O/xENxNQ4HaMQ5uSRK9n8WKKDDRSzwZ4syKKf wbkfj05vgFxrjCynVbm1zs2X2aGXh+PxPL/WHUaxzEP7KjYbLtCUZDRzOOrm+0LMktngT/k3 6+EZoLEM52hwwpIAzJoscyEz7QfqMOZtFm6xQnlvDQeIrHx0KUvwo/vgDLK3SuruG1CSHcR0 D24kEEUa044AIUKBS3b0b8AR7f6mP2NcnLpdsibtpabi9BzqAidcY/EjTaoea46HXALk/eJd 6OLkLE6UQe1PPzQC4jB7rErX2BxnSkHDw50xMgLRcl5/b1bOwE0EUhFfyAEIAKp7Cp8lqKTV CC9QiAf6QTIjW+lie5J44Ad++0k8gRgANZVWubQuCQ71gxDWLtxYfFkEXjG4TXV/MUtnOliG 5rc2E+ih6Dg61Y5PQakm9OwPIsOx+2R+iSW325ngln2UQrVPgloO83QiUoi7mBJPbcHlxkhZ bd3+EjFxSLIQogt29sTcg2oSh4oljUpz5niTt69IOfZx21kf29NfDE+Iw56gfrxI2ywZbu5o G+d0ZSp0lsovygpk4jK04fDTq0vxjEU5HjPcsXC4CSZdq5E2DrF4nOh1UHkHzeaXdYR2Bn1Y wTePfaHBFlvQzI+Li/Q6AD/uxbTM0vIcsUxrv3MNHCUAEQEAAcLBfgQYAQIACQUCUhFfyAIb LgEpCRCTQwmyVcgNcsBdIAQZAQIABgUCUhFfyAAKCRC22tOSFDh1UOlBB/94RsCJepNvmi/c YiNmMnm0mKb6vjv43OsHkqrrCqJSfo95KHyl5Up4JEp8tiJMyYT2mp4IsirZHxz/5lqkw9Az tcGAF3GlFsj++xTyD07DXlNeddwTKlqPRi/b8sppjtWur6Pm+wnAHp0mQ7GidhxHccFCl65w uT7S/ocb1MjrTgnAMiz+x87d48n1UJ7yIdI41Wpg2XFZiA9xPBiDuuoPwFj14/nK0elV5Dvq 4/HVgfurb4+fd74PV/CC/dmd7hg0ZRlgnB5rFUcFO7ywb7/TvICIIaLWcI42OJDSZjZ/MAzz BeXm263lHh+kFxkh2LxEHnQGHCHGpTYyi4Z3dv03HtkH/1SI8joQMQq00Bv+RdEbJXfEExrT u4gtdZAihwvy97OPA2nCdTAHm/phkzryMeOaOztI4PS8u2Ce5lUB6P/HcGtK/038KdX5MYST Fn8KUDt4o29bkv0CUXwDzS3oTzPNtGdryBkRMc9b+yn9+AdwFEH4auhiTQXPMnl0+G3nhKr7 jvzVFJCRif3OAhEm4vmBNDE3uuaXFQnbK56GJrnqVN+KX5Z3M7X3fA8UcVCGOEHXRP/aubiw Ngawj0V9x+43kUapFp+nF69R53UI65YtJ95ec4PTO/Edvap8h1UbdEOc4+TiYwY1TBuIKltY 1cnrjgAWUh/Ucvr++/KbD9tD6C8=
Message-ID: <554b1dff-a839-24da-c95f-3370aa811fa6@huitema.net>
Date: Mon, 6 Aug 2018 10:05:50 -0700
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1
MIME-Version: 1.0
In-Reply-To: <CABkgnnVFYMjWDk6zEEA8T_6qg+6qO9yAwVF70foMj4bXEdBaqQ@mail.gmail.com>
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
Content-Language: en-US
Subject: Re: The first octet
X-Originating-IP: 168.144.250.234
X-AntiSpamCloud-Domain: xsmtpout.mail2web.com
X-AntiSpamCloud-Username: 168.144.250.0/24
Authentication-Results: antispamcloud.com; auth=pass smtp.auth=168.144.250.0/24@xsmtpout.mail2web.com
X-AntiSpamCloud-Outgoing-Class: unsure
X-AntiSpamCloud-Outgoing-Evidence: Combined (0.35)
X-Recommended-Action: accept
X-Filter-ID: EX5BVjFpneJeBchSMxfU5mXQNEi+wqr+5PBri0Gk2FR602E9L7XzfQH6nu9C/Fh9KJzpNe6xgvOx q3u0UDjvO37pNwwF1lRXh5rzvPzo9Jts1ujulqUFmMITHM77eiVia+iMoztaKBa01OZvTScrmc7i TvJ2/ZGzVWB9scFAaCdIFaUvXN+CI+RGy3Me16pB81OoFFeyN79z+gPkYXfWpU5EpHPznVavQp4h 1cyzxbQFXqQgkkYk8mNUb0+uxPxhiSGt4Ko2sv7hY6P0Yu3OA+AIcPc2JG++Fh0y/kogNkMJ0464 etNXHOU+5Kb0QuG3bATPP9eeLWC5kDweN7crsXBXvrLBlKCVRjjdPbjQ4HmidG0pg2HLuLsP3mPp isElTs5Ex5aNZlcgVQFtAhrEij3dKxLhoxcmaInYbR5vlqETd+klAX+KFYkIxu6zxdn+X2XX9bIs GDSYq5OAASmskVIcMSgqtcKbU9La+AHiCFB9vuYMeDoXsMJDD9CZFW2Drvl3AsHuisl/RSyh5DLe 1OidX4Ts4xdG+C13IyWeZaLQFv21teFX4xX+heWMZvqWF8FcHzzV3acxBudgYcInb3YzWyKJcaJg isjiFj+QSl6Z4+t4LK79cWIqQA4tGr3po0jfgLl+Ahd0TIbt0Zij6hgeJ07QR0GiieIKGR3KfdmQ xACKGgjW6av7lJfpYBfZxaD1j8zstKyoNMHmOfd8LFwBl1z1+w2zS/h3e6UiVRePuofouKMePgHC OnvDWrETL004r80M5UVENe4iWC7t32eqA47D/juB1cx4exzYk7xEVhTEUT6xtIipPd5Oayzq647l NwN4qOsSZg+fYhVZGz1kOnf1peAVDGMbv2JVybbVwaDsyRiTeu4Ip+KAECko9HdE0Smt1e6HZuGs N7RwePAFMvX7q8M4x6bP/gjzw0OFbIWNJOiaifOc2xlkb46Pa4K5MPGI7fF8+j7E9IwdcQR2aish SbQcCCOvcJLn8v/2OKHH5lr9xXvSM4nM3avg
X-Report-Abuse-To: spam@quarantine6.antispamcloud.com
Archived-At: <https://mailarchive.ietf.org/arch/msg/quic/pqX4f5bzI2TLHFHHahpsOBk87wo>
X-BeenThere: quic@ietf.org
X-Mailman-Version: 2.1.27
Precedence: list
List-Id: Main mailing list of the IETF QUIC working group <quic.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/quic>, <mailto:quic-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/quic/>
List-Post: <mailto:quic@ietf.org>
List-Help: <mailto:quic-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/quic>, <mailto:quic-request@ietf.org?subject=subscribe>
X-List-Received-Date: Mon, 06 Aug 2018 17:27:05 -0000


On 8/5/2018 10:55 PM, Martin Thomson wrote:
> Long Header
>
> The long header uses the 0b1xxxxxxx pattern (128-255). The 7 bits we
> have are currently allocated to the 4 types of long header packet,
> using only 252-255.  All other values are currently unused.
>
> With respect to design constraints, there is only one that I'm aware
> of and that is a potential collision with RTP (and RTCP) on this octet
> (see RFC 7983), which use 0x10xxxxxx (128-191).
>
> The open question here is what we do with unused types.  We might
> debate creating a registry for unused values.  We might want to grease
> values.  We could even decide to encrypt these values (though the
> design of Retry makes that more difficult, because the contents of
> that packet aren't encrypted at all).
>
> I'm not aware of any plans to use these bits, except perhaps what
> might be done to be consistent with the short header changes, so we
> might have some latitude here.

We are actually greasing these bits with the version negotiation packets
-- the 7 unused bits of the VN packets are supposedly set to random
values. Of course, VN are special purpose packets and should not be used
all that often in production, but it is something...

-- Christian Huitema