Re: [quicwg/base-drafts] introduce a version alias mechanism (#2573)

Martin Thomson <> Wed, 10 April 2019 00:47 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id 381BE120142 for <>; Tue, 9 Apr 2019 17:47:00 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -8
X-Spam-Status: No, score=-8 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HTML_IMAGE_ONLY_32=0.001, HTML_MESSAGE=0.001, MAILING_LIST_MULTI=-1, RCVD_IN_DNSWL_HI=-5, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Authentication-Results: (amavisd-new); dkim=pass (1024-bit key)
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id GtXMRUJxYTeC for <>; Tue, 9 Apr 2019 17:46:58 -0700 (PDT)
Received: from ( []) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by (Postfix) with ESMTPS id 829A4120134 for <>; Tue, 9 Apr 2019 17:46:58 -0700 (PDT)
Date: Tue, 09 Apr 2019 17:46:57 -0700
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=pf2014; t=1554857217; bh=WgYvAFogB9onXbWYsE8W7XFXxmSahAy1qtAj0oLIPF0=; h=Date:From:Reply-To:To:Cc:In-Reply-To:References:Subject:List-ID: List-Archive:List-Post:List-Unsubscribe:From; b=kH6yTrt5IRw259+SvB+se1L95g23AiY8AKdMKfTHlZY1p62+yqgd+tFM2TndTVmHZ Mw8S8waQvH8kvVDYNqYs3rAR+NMKOeQxNoNc7MrLvQGreRxm83LMorE2ms1tMLngSL aoYfUS9dKROfKUpCEnb343pTMy/veqEsYfyUdINY=
From: Martin Thomson <>
Reply-To: quicwg/base-drafts <>
To: quicwg/base-drafts <>
Cc: Subscribed <>
Message-ID: <quicwg/base-drafts/pull/2573/review/>
In-Reply-To: <quicwg/base-drafts/pull/>
References: <quicwg/base-drafts/pull/>
Subject: Re: [quicwg/base-drafts] introduce a version alias mechanism (#2573)
Mime-Version: 1.0
Content-Type: multipart/alternative; boundary="--==_mimepart_5cad3d019fcfb_30583f93912d45c434274e"; charset="UTF-8"
Content-Transfer-Encoding: 7bit
Precedence: list
X-GitHub-Sender: martinthomson
X-GitHub-Recipient: quic-issues
X-GitHub-Reason: subscribed
X-Auto-Response-Suppress: All
Archived-At: <>
X-Mailman-Version: 2.1.29
List-Id: Notification list for GitHub issues related to the QUIC WG <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Wed, 10 Apr 2019 00:47:00 -0000

martinthomson commented on this pull request.

> @@ -4115,6 +4130,25 @@ preferred_address (0x000d):
 {: #fig-preferred-address title="Preferred Address format"}
+version_aliases (0x000e):
+: A list of version numbers that the server accepts as an alias for the
+  currently used versions. This transport parameter is only sent by the server.
+  Every version alias contains a lifetime in milliseconds. The alias is only valid
+  for that lifetime, clients MUST NOT use it after expiry.

If the idea that this lifetime is also a commitment to support a given version, then this isn't really a fully effective downgrade-prevention mechanism.  I expect that we'll see something good on that shortly.

I would instead prefer to say that the server is required to honour the alias for the entire advertised lifetime *unless* it also stops supporting that QUIC version.

You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub: