Date: Mon, 28 Jan 2013 11:09:24 -0500 From: John Baldwin <jhb@freebsd.org> To: freebsd-hackers@freebsd.org Cc: Tim Kientzle <kientzle@freebsd.org> Subject: Re: Testing SIOCADDMULTI? Message-ID: <201301281109.24879.jhb@freebsd.org> In-Reply-To: <7A0E9B71-0232-4808-B5D4-5B0D811B353C@kientzle.com> References: <AE65AFB2-A767-4457-B30A-007956A7D216@freebsd.org> <7A0E9B71-0232-4808-B5D4-5B0D811B353C@kientzle.com>
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On Sunday, January 27, 2013 1:51:12 am Tim Kientzle wrote: > > On Jan 26, 2013, at 3:56 PM, Tim Kientzle wrote: > > > My next TODO items for this network driver is to implement > > the SIOCADDMULTI and SIOCDELMULTI ioctls. > > Looking through other drivers (and net/if.c), I've > managed to implement ADDMULTI by adding > the multicast ethernet address to the list maintained > by the controller. > > DELMULTI seems trickier. Since if.c does not pass > the specific address being removed down to the > driver, it looks like I have no choice but to remove > every multicast address from the controller and then > re-insert all of the ones that are still valid. > > (This controller doesn't use a hash filter; it uses > a list of valid multicast addresses.) > > Is there a better approach? You should always reprogram the full table while holding if_maddr_rlock(). All the ioctl's tell you is that an entry was added or removed from that list. There is currently no race-free way for the stack to tell you which specific address to add or remove. > > I'm not quite sure what they do, though, and have > > no idea how to test them to see if they are working > > correctly. > > Would still appreciate any suggestions for how to test these. You can write a simple app to listen for UDP packets and have it join a multicast group and have another machine on the same network write a packet to the multicast group. However, a simpler test is to toggle the sysctl to enable multicast ping replies and to ping a multicast address from another machine after joining it on the test machine using mtest. -- John Baldwin
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