| Message ID | 1357650162-5554-1-git-send-email-jiri@resnulli.us |
|---|---|
| State | RFC, archived |
| Delegated to: | David Miller |
| Headers | show |
> When IFF_NOARP is set on a device, dev->dev_addr is used as *dst* > addr of sent frames. That does not make sense. Use rather bcast > address > instead. > > Signed-off-by: Jiri Pirko <jiri@resnulli.us> What did you test this on? I think this may have been intentional to avoid broadcasting. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Tue, Jan 08, 2013 at 06:11:55PM CET, stephen.hemminger@vyatta.com wrote: > >> When IFF_NOARP is set on a device, dev->dev_addr is used as *dst* >> addr of sent frames. That does not make sense. Use rather bcast >> address >> instead. >> >> Signed-off-by: Jiri Pirko <jiri@resnulli.us> > >What did you test this on? I think this may have been >intentional to avoid broadcasting. Thanks for looking at this Stephen. I tested this on two boxes connected via ethernet. I believe this may have been intentional, but what sense does it have to use dev_addr as destination address? That is what I do not understand. Also, what is the issue with sending all packets to broadcast when NOARP is set? In my opinion, it only makes sense. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
> Tue, Jan 08, 2013 at 06:11:55PM CET, stephen.hemminger@vyatta.com > wrote: > > > >> When IFF_NOARP is set on a device, dev->dev_addr is used as *dst* > >> addr of sent frames. That does not make sense. Use rather bcast > >> address > >> instead. > >> > >> Signed-off-by: Jiri Pirko <jiri@resnulli.us> > > > >What did you test this on? I think this may have been > >intentional to avoid broadcasting. > > Thanks for looking at this Stephen. > > I tested this on two boxes connected via ethernet. > > I believe this may have been intentional, but what sense does it have > to > use dev_addr as destination address? That is what I do not > understand. > > Also, what is the issue with sending all packets to broadcast when > NOARP is > set? In my opinion, it only makes sense. > It looks like NOARP devices are point-to-point and don't really have any concept of broadcast. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tuesday 2013-01-08 20:10, Stephen Hemminger wrote: >> >>Also, what is the issue with sending all packets to broadcast when >>NOARP is set? In my opinion, it only makes sense. > >It looks like NOARP devices are point-to-point and don't really have >any concept of broadcast. PTP links usually are NOARP, but NOARP does not necessarily imply a PTP link. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
From: Jiri Pirko <jiri@resnulli.us> Date: Tue, 8 Jan 2013 14:02:42 +0100 > When IFF_NOARP is set on a device, dev->dev_addr is used as *dst* > addr of sent frames. That does not make sense. Use rather bcast address > instead. > > Signed-off-by: Jiri Pirko <jiri@resnulli.us> The address is actually arbitrary in this case, I believe the current behavior is intentional, and even if it is not intentional since the address is arbitrary this change carrys only potential risk for zero gain. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
From: Jiri Pirko <jiri@resnulli.us> Date: Tue, 8 Jan 2013 18:45:38 +0100 > I believe this may have been intentional, but what sense does it have to > use dev_addr as destination address? That is what I do not understand. It's the only address we know isn't someone else's and is not broadcast. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c index 9547a273..19d5ac2 100644 --- a/net/ipv4/arp.c +++ b/net/ipv4/arp.c @@ -290,11 +290,11 @@ static int arp_constructor(struct neighbour *neigh) if (neigh->type == RTN_MULTICAST) { neigh->nud_state = NUD_NOARP; arp_mc_map(addr, neigh->ha, dev, 1); - } else if (dev->flags & (IFF_NOARP | IFF_LOOPBACK)) { + } else if (dev->flags & IFF_LOOPBACK) { neigh->nud_state = NUD_NOARP; memcpy(neigh->ha, dev->dev_addr, dev->addr_len); } else if (neigh->type == RTN_BROADCAST || - (dev->flags & IFF_POINTOPOINT)) { + (dev->flags & (IFF_POINTOPOINT | IFF_NOARP))) { neigh->nud_state = NUD_NOARP; memcpy(neigh->ha, dev->broadcast, dev->addr_len); }
When IFF_NOARP is set on a device, dev->dev_addr is used as *dst* addr of sent frames. That does not make sense. Use rather bcast address instead. Signed-off-by: Jiri Pirko <jiri@resnulli.us> --- net/ipv4/arp.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)