From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nicolas Dichtel Subject: Re: [RFC PATCH net-next 2/2] udp: add sk opt to allow sending pkt with src 0.0.0.0 Date: Thu, 14 Nov 2013 14:05:00 +0100 Message-ID: <5284CA7C.7030402@6wind.com> References: <20131105205744.GK8832@order.stressinduktion.org> <1383958474-6255-1-git-send-email-nicolas.dichtel@6wind.com> <1383958474-6255-2-git-send-email-nicolas.dichtel@6wind.com> <20131111.001803.110603937316567461.davem@davemloft.net> Reply-To: nicolas.dichtel@6wind.com Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: hannes@stressinduktion.org, netdev@vger.kernel.org, David.Laight@ACULAB.COM, jiri@resnulli.us, vyasevich@gmail.com, kuznet@ms2.inr.ac.ru, jmorris@namei.org, yoshfuji@linux-ipv6.org, kaber@trash.net, thaller@redhat.com, stephen@networkplumber.org To: David Miller Return-path: Received: from mail-wg0-f50.google.com ([74.125.82.50]:45718 "EHLO mail-wg0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753361Ab3KNNFD (ORCPT ); Thu, 14 Nov 2013 08:05:03 -0500 Received: by mail-wg0-f50.google.com with SMTP id k14so1905145wgh.29 for ; Thu, 14 Nov 2013 05:05:02 -0800 (PST) In-Reply-To: <20131111.001803.110603937316567461.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: Le 11/11/2013 06:18, David Miller a =E9crit : > From: Nicolas Dichtel > Date: Sat, 9 Nov 2013 01:54:34 +0100 > >> This feature allows to a send packets with address source set to 0.0= =2E0.0 even if >> an ip address is available on another interface. >> >> It's useful for DHCP client, to allow them to use UDP sockets and be= compliant >> with the RFC2131, Section 4.1: >> >> 4.1 Constructing and sending DHCP messages >> ... >> DHCP messages broadcast by a client prior to that client obtaini= ng >> its IP address must have the source address field in the IP head= er >> set to 0. >> >> Based on a previous work from >> Guillaume Gaudonville . >> >> Signed-off-by: Nicolas Dichtel > > This requirement of the RFC is inconsistent with a host based > addressing model, that which Linux employs, it assumes an interface > based one. There are some exceptions, for example when user tunes arp_ignore sysct= l ;-) > > The wording here is also very ambiguous. > > This RFC fails to even remotely consider what the right behavior > should be in a host based addressing environment at all, and anyone > reading this RFC should just accept that. I agree that this is ambiguous. And it's a 'must', not a 'MUST', which is not the same for an RFC ;-) > > Furthermore, the fact that you're implementing _addressing_ policy in > the UDP code makes this change even more unreasonable. > I made this choice because using 0.0.0.0, for TCP for example, seems a non-sense. But fair enough, let's drop this patch. Thank you, Nicolas