From mboxrd@z Thu Jan 1 00:00:00 1970 From: Johannes Berg Subject: Re: multicasting netlink messages to groups > 31 from userspace Date: Wed, 04 Jul 2007 16:18:22 +0200 Message-ID: <1183558702.3812.33.camel@johannes.berg> References: <1183492286.4021.21.camel@johannes.berg> <468BAADC.4030203@trash.net> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-P7qH+uvW6LbZFJfruoyM" Cc: netdev , jamal , Thomas Graf To: Patrick McHardy Return-path: Received: from crystal.sipsolutions.net ([195.210.38.204]:49484 "EHLO sipsolutions.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758557AbXGDOR3 (ORCPT ); Wed, 4 Jul 2007 10:17:29 -0400 In-Reply-To: <468BAADC.4030203@trash.net> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org --=-P7qH+uvW6LbZFJfruoyM Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Wed, 2007-07-04 at 16:12 +0200, Patrick McHardy wrote: > Johannes Berg wrote: > > Hey, > >=20 > > 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 :/ >=20 >=20 > 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 --=-P7qH+uvW6LbZFJfruoyM Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Comment: Johannes Berg (powerbook) iD8DBQBGi6wu/ETPhpq3jKURAsF5AKCBZHC+Eq+F3KL5SGGjd1YskfzjCQCfTv2B crWNwCJl/OCcmuqq2Pf6FQo= =F9GM -----END PGP SIGNATURE----- --=-P7qH+uvW6LbZFJfruoyM--