svn commit: r304436 - in head: . sys/netinet

[Bruce Simpson]

On 20/08/16 12:33, Bruce Simpson wrote:
> This potentially breaks reception of IPv4 broadcasts where FreeBSD is
> the endpoint at the end of a P2P interface, or other forms of links,
> where there is no guarantee that the link layer will set M_BCAST (or
> indeed M_MCAST).

I appreciate it probably looks like a quick win, but if it's only been 
tested with Ethernet (it looks like it has only been written with 
Ethernet in mind), it does strongly look as if it breaks broadcast for 
UDP/IPv4 in other situations.

So, maybe it should be backed out ASAP. (I haven't tested this code.)

It is perfectly legal for broadcast packets to be addressed to the end 
of a P2P or non-Ethernet link, which may not set M_BCAST or M_MCAST. The 
classic example is ATM (Non-Broadcast, Multiple Access (NBMA)) but the 
situation may be readily observed with loopback or tunnels.

The same issue doesn't exist in your output path change, which looks 
sane. The same issue doesn't exist with IPv6 where broadcast is dead.