A few issues with the bridge snooping were identified and fixed
upstream in OpenWRT:
* "firewall: Allow IGMP and MLD input on WAN" (r45613)
* "kernel: bridge: backport two snooping related patches" (r45783)
* netifd: "bridge: Fix multicast_to_unicast feature by hairpin+isolate"
(OW: "netifd: update to the latest version, adds multicast-to-unicast fixes" (r46719))
* "kernel: bridge, multicast-to-unicast: assign src after pskb_may_pull()" (r46721)
* "kernel: bridge, multicast-to-unicast: fix echoes on STA" (46765)
These have very likely caused issues with the bridge snooping before,
which led to disabling it in the past. Let's reenable the multicast
snooping now that they were fixed for reduced multicast overhead on the
wifi.
Advantages are the following:
This mildly reduces overhead on the mesh layer. And significantly reduces
overhead on the AP interface and therefore significantly increases
available airtime (the currently most significant scalability bottleneck).
Secondly removes an easy, often accidental node-local Denial-of-Service
vector based on multicast flooding / streaming.
Thirdly, makes node-local multicast streaming feasible.
Finally should noticably increase battery life of mobile devices.
Note: bridge querier is disabled for br-wan. We want to avoid becoming
too "bossy"/"noisy" on a foreign network.
Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
The mesh side has become fairly huge in many communities. Up to
a few thousand entries can currently be found in the forwarding
database (fdb) of a bridge for its bridge port bat0.
The bridge fdb is kind of redundant to the batman-adv global translation
table here. Therefore this patch tries to reduce memory footprint by
following an approach similar to the IGMP/MLD split patchset approach:
Make the bridge oblivious not only regarding multicast listeners towards
the mesh but with this patch unicast hosts on the mesh, too.
If the destination of an ethernet frame is known by the bridge to be a
local one, then the frame is forwarded to the according port. If it is
unknown, then the frame is forwarded to the wifi AP interface and bat0.
mac80211 and batman-adv then know whether to drop or forward a frame
further through their own book-keeping.
Note that unicast-flood is not disabled for the wifi AP bridge port, nor
is learning disabled on the wifi AP. This is mainly to keep the
configuration in UCI and according setup scripts simple ;). However, not
disalbling unicast-flood on the wifi AP interface might also give a
minor latency improvement for newly joining wifi clients.
Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
Some drivers (mt76) don't support arbitrary MAC addresses. Use the
addresses provided by the driver (avoiding the primary address) by default,
but fall back to our has-based scheme when the driver doesn't provide
(enough) addresses.
