svn commit: r206452 - head/sys/netinet

[Bruce Simpson]

On 04/16/10 09:23, Alexander Leidinger wrote:
>
>> IP multicast group membership is always scoped to physical links [1]. 
>> The 4.4BSD API originally used the "primary IP address" to identify 
>> each link. Unfortunately this is not a persistent identifier, 
>> especially so in the use-case which had problems.
>
>
> Is/was this the reason why multicast does not work in jails?

The above point is totally unrelated to jail.

I think the problem with jail is the fact that to receive multicast, 
sockets normally need to be bound to INADDR_ANY. Obviously, jail changes 
socket behaviour in interesting ways.

This may require refactoring udp_input() considerably. We use the 4.4BSD 
legacy LIST_FOREACH() loop to deliver, rather than using a fan-in map 
(which is the Windows/Solaris approach).

Linux also has 4.4BSD semantics, but can work around this by examining 
the SO_BINDTODEVICE option in the same path.