From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jesper Dangaard Brouer Subject: Re: [PATCH net-next] ipv4: accept u8 in IP_TOS ancillary data Date: Thu, 8 Sep 2016 11:15:19 +0200 Message-ID: <20160908111519.62af94bf@redhat.com> References: <1473310376.15733.26.camel@edumazet-glaptop3.roam.corp.google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: David Miller , netdev , Francesco Fusco , Maciej =?UTF-8?B?xbtlbmN6eWtvd3NraQ==?= , brouer@redhat.com To: Eric Dumazet Return-path: Received: from mx1.redhat.com ([209.132.183.28]:60068 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933325AbcIHJPZ (ORCPT ); Thu, 8 Sep 2016 05:15:25 -0400 In-Reply-To: <1473310376.15733.26.camel@edumazet-glaptop3.roam.corp.google.com> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 07 Sep 2016 21:52:56 -0700 Eric Dumazet wrote: > From: Eric Dumazet > > In commit f02db315b8d8 ("ipv4: IP_TOS and IP_TTL can be specified as > ancillary data") Francesco added IP_TOS values specified as integer. > > However, kernel sends to userspace (at recvmsg() time) an IP_TOS value > in a single byte, when IP_RECVTOS is set on the socket. > > It can be very useful to reflect all ancillary options as given by the > kernel in a subsequent sendmsg(), instead of aborting the sendmsg() with > EINVAL after Francesco patch. > > So this patch extends IP_TOS ancillary to accept an u8, so that an UDP > server can simply reuse same ancillary block without having to mangle > it. > > Jesper can then augment > https://github.com/netoptimizer/network-testing/blob/master/src/udp_example02.c > to add TOS reflection ;) This is actually your old program ;-) Do I need to change anything, as I'm just bouncing the packet back with sendmsg() ? > Fixes: f02db315b8d8 ("ipv4: IP_TOS and IP_TTL can be specified as ancillary data") > Signed-off-by: Eric Dumazet > Cc: Francesco Fusco > Cc: Jesper Dangaard Brouer Looks like a good fix, Acked-by: Jesper Dangaard Brouer > --- > net/ipv4/ip_sockglue.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c > index 71a52f4d4cffba2db9353f43dc817689bf4fab10..af4919792b6a812041dcb18ff30aa8b27482c7a2 100644 > --- a/net/ipv4/ip_sockglue.c > +++ b/net/ipv4/ip_sockglue.c > @@ -284,9 +284,12 @@ int ip_cmsg_send(struct sock *sk, struct msghdr *msg, struct ipcm_cookie *ipc, > ipc->ttl = val; > break; > case IP_TOS: > - if (cmsg->cmsg_len != CMSG_LEN(sizeof(int))) > + if (cmsg->cmsg_len == CMSG_LEN(sizeof(int))) > + val = *(int *)CMSG_DATA(cmsg); > + else if (cmsg->cmsg_len == CMSG_LEN(sizeof(u8))) > + val = *(u8 *)CMSG_DATA(cmsg); > + else > return -EINVAL; > - val = *(int *)CMSG_DATA(cmsg); > if (val < 0 || val > 255) > return -EINVAL; > ipc->tos = val; > > -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat Author of http://www.iptv-analyzer.org LinkedIn: http://www.linkedin.com/in/brouer