batman-adv: network coding - save overheard and tx packets for decoding

To be able to decode a network coded packet, a node must already know
one of the two coded packets. This is done by buffering skbs before
transmission and buffering packets sniffed with promiscuous mode from
other hosts.

Packets are kept in a buffer similar to the one with forward-skbs: A
hash table, where each entry, which corresponds to a src-dst pair, has a
linked list packets.

Signed-off-by: Martin Hundebøll <martin@hundeboll.net>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <ordex@autistici.org>

1 files changed, 11 insertions, 2 deletions

diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index 44fda7c6171e..8f88967ff14b 100644
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -1047,7 +1047,7 @@ int batadv_recv_unicast_packet(struct sk_buff *skb,
         struct batadv_unicast_4addr_packet *unicast_4addr_packet;
         uint8_t *orig_addr;
         struct batadv_orig_node *orig_node = NULL;
-        int hdr_size = sizeof(*unicast_packet);
+        int check, hdr_size = sizeof(*unicast_packet);
         bool is4addr;
 
         unicast_packet = (struct batadv_unicast_packet *)skb->data;
@@ -1058,7 +1058,16 @@ int batadv_recv_unicast_packet(struct sk_buff *skb,
         if (is4addr)
                 hdr_size = sizeof(*unicast_4addr_packet);
 
-        if (batadv_check_unicast_packet(skb, hdr_size) < 0)
+        /* function returns -EREMOTE for promiscuous packets */
+        check = batadv_check_unicast_packet(skb, hdr_size);
+
+        /* Even though the packet is not for us, we might save it to use for
+         * decoding a later received coded packet
+         */
+        if (check == -EREMOTE)
+                batadv_nc_skb_store_sniffed_unicast(bat_priv, skb);
+
+        if (check < 0)
                 return NET_RX_DROP;
 
         if (!batadv_check_unicast_ttvn(bat_priv, skb))