Return-path: Received: from purr.warmcat.com ([87.106.142.209]:41232 "EHLO mailserver.mog.warmcat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759473AbXHCKtO (ORCPT ); Fri, 3 Aug 2007 06:49:14 -0400 Message-ID: <46B30828.3000507@warmcat.com> Date: Fri, 03 Aug 2007 11:49:12 +0100 From: Andy Green MIME-Version: 1.0 To: Johannes Berg CC: Ulrich Kunitz , linux-wireless , Daniel Drake Subject: Re: mac80211 driver interface semantics References: <46B27729.5030406@gentoo.org> <20070803052935.GA12683@deine-taler.de> <46B2E06F.4090706@warmcat.com> <1186134894.4647.24.camel@johannes.berg> <46B3032C.5040306@warmcat.com> <1186137166.4647.34.camel@johannes.berg> <46B304FF.3000305@warmcat.com> <1186137715.4647.36.camel@johannes.berg> In-Reply-To: <1186137715.4647.36.camel@johannes.berg> Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-wireless-owner@vger.kernel.org List-ID: Somebody in the thread at some point said: > On Fri, 2007-08-03 at 11:35 +0100, Andy Green wrote: > >> Right, but since we marked up the skb "the integrity of the IP checksum >> is unknown", if anything wants to use the packet it should re-check it >> itself. Won't that do? > > It'll check the IP checksum anyway since we don't have hardware that > checks it as far as I know, but we want to check the FCS. I guess I didn't understand where the problem can come from, then. ''Because if you have both a hard monitor and a regular interface (monitor_during_oper allowed) then we will never check the CRC on frames that enter the networking path and can get corrupted TCP packets in etc.'' If the rest of the networking stack didn't trust the packet anyway and confirms the IP-level checksum, then it can make its own opinion about the packet. For stuff that is looking at the whole rx packet including the ieee80211 header, we can add a bit in the radiotap flags on top of the packet noting that it failed FCS. -Andy