From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [RFC PATCH net-next 2/2] udp: add sk opt to allow sending pkt with src 0.0.0.0 Date: Mon, 11 Nov 2013 00:18:03 -0500 (EST) Message-ID: <20131111.001803.110603937316567461.davem@davemloft.net> 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> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit 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: nicolas.dichtel@6wind.com Return-path: Received: from shards.monkeyblade.net ([149.20.54.216]:52322 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751197Ab3KKFSG (ORCPT ); Mon, 11 Nov 2013 00:18:06 -0500 In-Reply-To: <1383958474-6255-2-git-send-email-nicolas.dichtel@6wind.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Nicolas Dichtel Date: Sat, 9 Nov 2013 01:54:34 +0100 > This feature allows to a send packets with address source set to 0.0.0.0 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 obtaining > its IP address must have the source address field in the IP header > 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. 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. Furthermore, the fact that you're implementing _addressing_ policy in the UDP code makes this change even more unreasonable.