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, 28 insertions, 1 deletions

diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index 859679b08286..1826699314b7 100644
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -28,6 +28,7 @@
 #include "vis.h"
 #include "unicast.h"
 #include "bridge_loop_avoidance.h"
+#include "distributed-arp-table.h"
 
 static int batadv_route_unicast_packet(struct sk_buff *skb,
                                        struct batadv_hard_iface *recv_if);
@@ -985,11 +986,13 @@ int batadv_recv_unicast_packet(struct sk_buff *skb,
         struct batadv_priv *bat_priv = netdev_priv(recv_if->soft_iface);
         struct batadv_unicast_packet *unicast_packet;
         int hdr_size = sizeof(*unicast_packet);
+        bool is4addr;
 
         unicast_packet = (struct batadv_unicast_packet *)skb->data;
 
+        is4addr = unicast_packet->header.packet_type == BATADV_UNICAST_4ADDR;
         /* the caller function should have already pulled 2 bytes */
-        if (unicast_packet->header.packet_type == BATADV_UNICAST_4ADDR)
+        if (is4addr)
                 hdr_size = sizeof(struct batadv_unicast_4addr_packet);
 
         if (batadv_check_unicast_packet(skb, hdr_size) < 0)
@@ -1000,9 +1003,17 @@ int batadv_recv_unicast_packet(struct sk_buff *skb,
 
         /* packet for me */
         if (batadv_is_my_mac(unicast_packet->dest)) {
+                if (batadv_dat_snoop_incoming_arp_request(bat_priv, skb,
+                                                          hdr_size))
+                        goto rx_success;
+                if (batadv_dat_snoop_incoming_arp_reply(bat_priv, skb,
+                                                        hdr_size))
+                        goto rx_success;
+
                 batadv_interface_rx(recv_if->soft_iface, skb, recv_if, hdr_size,
                                     NULL);
 
+rx_success:
                 return NET_RX_SUCCESS;
         }
 
@@ -1038,8 +1049,17 @@ int batadv_recv_ucast_frag_packet(struct sk_buff *skb,
                 if (!new_skb)
                         return NET_RX_SUCCESS;
 
+                if (batadv_dat_snoop_incoming_arp_request(bat_priv, new_skb,
+                                                          hdr_size))
+                        goto rx_success;
+                if (batadv_dat_snoop_incoming_arp_reply(bat_priv, new_skb,
+                                                        hdr_size))
+                        goto rx_success;
+
                 batadv_interface_rx(recv_if->soft_iface, new_skb, recv_if,
                                     sizeof(struct batadv_unicast_packet), NULL);
+
+rx_success:
                 return NET_RX_SUCCESS;
         }
 
@@ -1131,9 +1151,16 @@ int batadv_recv_bcast_packet(struct sk_buff *skb,
         if (batadv_bla_is_backbone_gw(skb, orig_node, hdr_size))
                 goto out;
 
+        if (batadv_dat_snoop_incoming_arp_request(bat_priv, skb, hdr_size))
+                goto rx_success;
+        if (batadv_dat_snoop_incoming_arp_reply(bat_priv, skb, hdr_size))
+                goto rx_success;
+
         /* broadcast for me */
         batadv_interface_rx(recv_if->soft_iface, skb, recv_if, hdr_size,
                             orig_node);
+
+rx_success:
         ret = NET_RX_SUCCESS;
         goto out;