From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <eric.dumazet@gmail.com>
Received: from mail-bk0-f43.google.com (mail-bk0-f43.google.com
	[209.85.214.43]) (using TLSv1 with cipher RC4-SHA (128/128 bits))
	(Client CN "smtp.gmail.com",
	Issuer "Google Internet Authority" (verified OK))
	by huchra.bufferbloat.net (Postfix) with ESMTPS id 8A36821F0E8;
	Mon, 14 May 2012 11:31:52 -0700 (PDT)
Received: by bkty5 with SMTP id y5so9253144bkt.16
	for <multiple recipients>; Mon, 14 May 2012 11:31:50 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113;
	h=subject:from:to:cc:in-reply-to:references:content-type:date
	:message-id:mime-version:x-mailer:content-transfer-encoding;
	bh=lDI1hSi9773UswOE8dNize0+WDFDj4q+th5qGmEcWyw=;
	b=uP6Uj98/6IwxLlPJU4oUCfRc4EGpi+m4wyjt3+IPYRhbDAcBU8YYzKdYVQW6R5Ujr9
	aP3nNBthrr8UMsPokObh8xJ/wiaK8Wb/eovB3Nwh+CqCCn24B5kCGKf/SHsOARyE8SMe
	gyAq+4ueTHjPIOJlXdCgy9BOycIY/f5Rg8aGm2QZGXiM4hT2ogsLEIZCYAELdOxJwFIQ
	WQK7tTym9/tYTCy1Vr6p9Mlm2AfrMC1iIuJxHrAS2jFLun7pgLaRt9ujvdeWFp9YOcof
	+SX617e62J1EOFEJC0Js/e73eyijC+gmscMJuUNOdOUwLhS1TcFWorZflqKQzes+n6OH
	y2Rg==
Received: by 10.205.133.212 with SMTP id hz20mr3384415bkc.99.1337020310458;
	Mon, 14 May 2012 11:31:50 -0700 (PDT)
Received: from [192.168.178.86] ([74.125.122.49])
	by mx.google.com with ESMTPS id z14sm36571439bky.15.2012.05.14.11.31.48
	(version=SSLv3 cipher=OTHER); Mon, 14 May 2012 11:31:49 -0700 (PDT)
From: Eric Dumazet <eric.dumazet@gmail.com>
To: Juliusz Chroboczek <jch@pps.jussieu.fr>
In-Reply-To: <7id366vcwb.fsf@lanthane.pps.jussieu.fr>
References: <4FB129EC.90200@gmail.com> <7imx5a3b4t.fsf@lanthane.pps.jussieu.fr>
	<1337018621.8512.592.camel@edumazet-glaptop>
	<7id366vcwb.fsf@lanthane.pps.jussieu.fr>
Content-Type: text/plain; charset="UTF-8"
Date: Mon, 14 May 2012 20:31:47 +0200
Message-ID: <1337020307.8512.599.camel@edumazet-glaptop>
Mime-Version: 1.0
X-Mailer: Evolution 2.28.3 
Content-Transfer-Encoding: 7bit
Cc: codel@lists.bufferbloat.net, bloat@lists.bufferbloat.net
Subject: Re: [Codel] [Bloat] better tc support for bittorrent/diffserv
X-BeenThere: codel@lists.bufferbloat.net
X-Mailman-Version: 2.1.13
Precedence: list
List-Id: CoDel AQM discussions <codel.lists.bufferbloat.net>
List-Unsubscribe: <https://lists.bufferbloat.net/options/codel>,
	<mailto:codel-request@lists.bufferbloat.net?subject=unsubscribe>
List-Archive: <https://lists.bufferbloat.net/pipermail/codel>
List-Post: <mailto:codel@lists.bufferbloat.net>
List-Help: <mailto:codel-request@lists.bufferbloat.net?subject=help>
List-Subscribe: <https://lists.bufferbloat.net/listinfo/codel>,
	<mailto:codel-request@lists.bufferbloat.net?subject=subscribe>
X-List-Received-Date: Mon, 14 May 2012 18:31:53 -0000

On Mon, 2012-05-14 at 20:24 +0200, Juliusz Chroboczek wrote:
> > There is an API to set ECN on UDP packets.
> >
> > setsockopt() IP_TOS, with val = 2
> 
> Interesting, I didn't realise that.  Is it also possible to read the ECN
> bits?


Yep

man 7 ip

     IP_RECVTOS (since Linux 2.2)
       If enabled the IP_TOS ancillary message is passed with incoming packets.
      It contains a byte which specifies the Type of Service/Precedence field
      of the packet header.  Expects a boolean integer flag.