On Wed, 2007-07-04 at 16:12 +0200, Patrick McHardy wrote: > Johannes Berg wrote: > > Hey, > > > > Looking through the code that uses NL_NONROOT_SEND I just realised that > > it's impossible to send multicast messages from userspace to multicast > > groups with IDs higher than 31. That's not really good given that > > everywhere else we handle multicast groups up to 2^32-1 :/ > > > Why do you want to send to a multicast group from userspace?
Why not, what's wrong with that? Actually, I think I mentioned this earlier, I was thinking about doing wireless configuration as a group where both the kernel and possibly a userspace process listen on that multicast group and processes that want to configure a device just send to that group. Then the kernel ignores the message if a userspace process is handling the specific device completely. For example changing the BSSID: if the kernel is doing MLME then it changes the BSSID, but if a userspace process is doing it then the kernel doesn't do anything since BSSID changing is a pure MLME function, but for consistency it'd be nice if both could be done the same way, hence a multicast group. This was actually suggested by Herbert since it's easy to find out if that multicast group has a listener and not so easy if a special generic netlink socket in userspace is (still) open. johannes
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