On Friday, September 4, 2020 8:28:00 PM CEST Linus Lüssing wrote:
> The unicast packet rerouting code makes several assumptions. For
> instance it assumes that there is always exactly one destination in the
> TT. This breaks for multicast frames in a unicast packets in several ways:
> 
> For one thing if there is actually no TT entry and the destination node
> was selected due to the multicast tvlv flags it announced. Then an
> intermediate node will wrongly drop the packet.
> 
> For another thing if there is a TT entry but the TTVN of this entry is
> newer than the originally addressed destination node: Then the
> intermediate node will wrongly redirect the packet, leading to
> duplicated multicast packets at a multicast listener and missing
> packets at other multicast listeners or multicast routers.
> 
> Fixing this by not applying the unicast packet rerouting to batman-adv
> unicast packets with a multicast payload. We are not able to detect a
> roaming multicast listener at the moment and will just continue to send
> the multicast frame to both the new and old destination for a while in
> case of such a roaming multicast listener.
> 
> Fixes: cea194d90b11 ("batman-adv: improved client announcement mechanism")
> Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>

Acked-by: Simon Wunderlich <sw@simonwunderlich.de>