batman-adv: Distributed ARP Table - add snooping functions for ARP messages

In case of an ARP message going in or out the soft_iface, it is intercepted and
a special action is performed. In particular the DHT helper functions previously
implemented are used to store all the ARP entries belonging to the network in
order to provide a fast and unicast lookup instead of the classic broadcast
flooding mechanism.
Each node stores the entries it is responsible for (following the DHT rules) in
its soft_iface ARP table. This makes it possible to reuse the kernel data
structures and functions for ARP management.

Signed-off-by: Antonio Quartulli <ordex@autistici.org>

1 files changed, 15 insertions, 1 deletions

diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c
index 2f123a1b174b..9dc0ae1d4da3 100644
--- a/net/batman-adv/soft-interface.c
+++ b/net/batman-adv/soft-interface.c
@@ -20,6 +20,7 @@
 #include "main.h"
 #include "soft-interface.h"
 #include "hard-interface.h"
+#include "distributed-arp-table.h"
 #include "routing.h"
 #include "send.h"
 #include "debugfs.h"
@@ -155,6 +156,7 @@ static int batadv_interface_tx(struct sk_buff *skb,
         short vid __maybe_unused = -1;
         bool do_bcast = false;
         uint32_t seqno;
+        unsigned long brd_delay = 1;
 
         if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
                 goto dropped;
@@ -224,6 +226,13 @@ static int batadv_interface_tx(struct sk_buff *skb,
                 if (!primary_if)
                         goto dropped;
 
+                /* in case of ARP request, we do not immediately broadcasti the
+                 * packet, instead we first wait for DAT to try to retrieve the
+                 * correct ARP entry
+                 */
+                if (batadv_dat_snoop_outgoing_arp_request(bat_priv, skb))
+                        brd_delay = msecs_to_jiffies(ARP_REQ_DELAY);
+
                 if (batadv_skb_head_push(skb, sizeof(*bcast_packet)) < 0)
                         goto dropped;
 
@@ -245,7 +254,7 @@ static int batadv_interface_tx(struct sk_buff *skb,
                 seqno = atomic_inc_return(&bat_priv->bcast_seqno);
                 bcast_packet->seqno = htonl(seqno);
 
-                batadv_add_bcast_packet_to_list(bat_priv, skb, 1);
+                batadv_add_bcast_packet_to_list(bat_priv, skb, brd_delay);
 
                 /* a copy is stored in the bcast list, therefore removing
                  * the original skb.
@@ -260,6 +269,11 @@ static int batadv_interface_tx(struct sk_buff *skb,
                                 goto dropped;
                 }
 
+                if (batadv_dat_snoop_outgoing_arp_request(bat_priv, skb))
+                        goto dropped;
+
+                batadv_dat_snoop_outgoing_arp_reply(bat_priv, skb);
+
                 ret = batadv_unicast_send_skb(bat_priv, skb);
                 if (ret != 0)
                         goto dropped_freed;