batman-adv: Simple (re)broadcast avoidance

With this patch, (re)broadcasting on a specific interfaces is avoided:

* No neighbor: There is no need to broadcast on an interface if there
  is no node behind it.

* Single neighbor is source: If there is just one neighbor on an
  interface and if this neighbor is the one we actually got this
  broadcast packet from, then we do not need to echo it back.

* Single neighbor is originator: If there is just one neighbor on
  an interface and if this neighbor is the originator of this
  broadcast packet, then we do not need to echo it back.

Goodies for BATMAN V:

("Upgrade your BATMAN IV network to V now to get these for free!")

Thanks to the split of OGMv1 into two packet types, OGMv2 and ELP
that is, we can now apply the same optimizations stated above to OGMv2
packets, too.

Furthermore, with BATMAN V, rebroadcasts can be reduced in certain
multi interface cases, too, where BATMAN IV cannot. This is thanks to
the removal of the "secondary interface originator" concept in BATMAN V.

Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index 0d46aeac9fd9..98ebac05c571 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -408,6 +408,7 @@ struct batadv_hardif_neigh_node_bat_v {
  * struct batadv_hardif_neigh_node - unique neighbor per hard-interface
  * @list: list node for batadv_hard_iface::neigh_list
  * @addr: the MAC address of the neighboring interface
+ * @orig: the address of the originator this neighbor node belongs to
  * @if_incoming: pointer to incoming hard-interface
  * @last_seen: when last packet via this neighbor was received
  * @bat_v: B.A.T.M.A.N. V private data
@@ -417,6 +418,7 @@ struct batadv_hardif_neigh_node_bat_v {
 struct batadv_hardif_neigh_node {
 	struct hlist_node list;
 	u8 addr[ETH_ALEN];
+	u8 orig[ETH_ALEN];
 	struct batadv_hard_iface *if_incoming;
 	unsigned long last_seen;
 #ifdef CONFIG_BATMAN_ADV_BATMAN_V