From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Dykstra Subject: Re: [PATCH] net: Keep interface binding when sending packets with ipi_ifindex = 0 Date: Wed, 29 Jul 2009 19:10:21 -0500 Message-ID: <1248912621.13447.12.camel@merlyn> References: <6c039e090907231439t1def08a4n10978733bee55bec@mail.gmail.com> <20090727144402.513369f1.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Chia-chi Yeh , linux-kernel@vger.kernel.org, netdev@vger.kernel.org To: Andrew Morton Return-path: In-Reply-To: <20090727144402.513369f1.akpm@linux-foundation.org> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Mon, 2009-07-27 at 14:44 -0700, Andrew Morton wrote: > (cc netdev) > > On Thu, 23 Jul 2009 14:39:28 -0700 > Chia-chi Yeh (_________) wrote: > > > In IPv4, sending a packet with ipi_ifindex = 0 via an interface-bound > > socket will unbind the packet to that interface. This behavior is > > different from IPv6 which treats ipi6_ifindex = 0 as unspecified. > > Furthermore, IPv6 does not allow sending packets to other interface > > than the bound one, but I am not sure if it is necessary in IPv4. The > > following patch keeps the interface binding when ipi_ifindex = 0. > > > > Thanks, > > Chia-chi > > > > --- a/net/ipv4/ip_sockglue.c 2009-07-24 04:50:45.000000000 +0800 > > +++ b/net/ipv4/ip_sockglue.c 2009-07-24 04:51:09.000000000 +0800 > > @@ -213,7 +213,8 @@ > > if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct in_pktinfo))) > > return -EINVAL; > > info = (struct in_pktinfo *)CMSG_DATA(cmsg); > > - ipc->oif = info->ipi_ifindex; > > + if (info->ipi_ifindex) > > + ipc->oif = info->ipi_ifindex; > > ipc->addr = info->ipi_spec_dst.s_addr; > > break; > > } A convenient copy of the man page says "When ipi_ifindex is not zero the primary local address of the interface specified by the index overwrites ipi_spec_dst for the routing table lookup." But this is changing API behavior that's been this way since at least the beginning of git history. I guess Dave's letting this stand. I'm posting this just to make sure this is an explicit decision. -- John