[B.A.T.M.A.N.] [PATCHv2 2/7] batman-adv: speed up dat by snooping received ip traffic

[Andreas Pape <apape@phoenixcontact.com>]

Speeding up dat address lookup is achieved by snooping all incoming ip
traffic. This especially increases the propability in bla setups that
a gateway into a common backbone network already has a fitting dat entry
to answer incoming ARP requests directly coming from the backbone
network thus further reducing ARP traffic in the mesh.

Signed-off-by: Andreas Pape <apape@phoenixcontact.com>
---
 net/batman-adv/distributed-arp-table.c |   18 ++++++++++++++++++
 net/batman-adv/distributed-arp-table.h |    9 ++++++++-
 net/batman-adv/soft-interface.c        |   22 +++++++++++++++++++++-
 3 files changed, 47 insertions(+), 2 deletions(-)

diff --git a/net/batman-adv/distributed-arp-table.c b/net/batman-adv/distributed-arp-table.c
index a9152e7..0f899b9 100644
--- a/net/batman-adv/distributed-arp-table.c
+++ b/net/batman-adv/distributed-arp-table.c
@@ -362,6 +362,24 @@ out:
 		batadv_dat_entry_put(dat_entry);
 }

+/**
+ * batadv_dat_entry_check - check and update a dat entry
+ * @bat_priv: the bat priv with all the soft interface information
+ * @ip: ipv4 to add/edit
+ * @mac_addr: mac address to assign to the given ipv4
+ * @vid: VLAN identifier
+ *
+ * checks additionally, if dat is enabled. can be called from other modules.
+ */
+void batadv_dat_entry_check(struct batadv_priv *bat_priv, __be32 ip,
+			    u8 *mac_addr, unsigned short vid)
+{
+	if (!atomic_read(&bat_priv->distributed_arp_table))
+		return;
+
+	batadv_dat_entry_add(bat_priv, ip, mac_addr, vid);
+}
+
 #ifdef CONFIG_BATMAN_ADV_DEBUG

 /**
diff --git a/net/batman-adv/distributed-arp-table.h b/net/batman-adv/distributed-arp-table.h
index 813ecea..e1b4848 100644
--- a/net/batman-adv/distributed-arp-table.h
+++ b/net/batman-adv/distributed-arp-table.h
@@ -80,7 +80,8 @@ batadv_dat_init_own_addr(struct batadv_priv *bat_priv,
 int batadv_dat_init(struct batadv_priv *bat_priv);
 void batadv_dat_free(struct batadv_priv *bat_priv);
 int batadv_dat_cache_seq_print_text(struct seq_file *seq, void *offset);
-
+void batadv_dat_entry_check(struct batadv_priv *bat_priv, __be32 ip,
+			    u8 *mac_addr, unsigned short vid);
 /**
  * batadv_dat_inc_counter - increment the correct DAT packet counter
  * @bat_priv: the bat priv with all the soft interface information
@@ -173,6 +174,12 @@ static inline void batadv_dat_inc_counter(struct batadv_priv *bat_priv,
 {
 }

+static inline
+void batadv_dat_entry_check(struct batadv_priv *bat_priv, __be32 ip,
+			    u8 *mac_addr, unsigned short vid)
+{
+}
+
 #endif /* CONFIG_BATMAN_ADV_DAT */

 #endif /* _NET_BATMAN_ADV_DISTRIBUTED_ARP_TABLE_H_ */
diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c
index 0710379..f031781 100644
--- a/net/batman-adv/soft-interface.c
+++ b/net/batman-adv/soft-interface.c
@@ -28,6 +28,7 @@
 #include <linux/fs.h>
 #include <linux/if_ether.h>
 #include <linux/if_vlan.h>
+#include <linux/ip.h>
 #include <linux/jiffies.h>
 #include <linux/kernel.h>
 #include <linux/kref.h>
@@ -390,6 +391,7 @@ void batadv_interface_rx(struct net_device *soft_iface,
 	__be16 ethertype = htons(ETH_P_BATMAN);
 	struct vlan_ethhdr *vhdr;
 	struct ethhdr *ethhdr;
+	struct iphdr *iphdr;
 	unsigned short vid;
 	bool is_bcast;

@@ -412,11 +414,29 @@ void batadv_interface_rx(struct net_device *soft_iface,
 	ethhdr = eth_hdr(skb);

 	switch (ntohs(ethhdr->h_proto)) {
+	case ETH_P_IP:
+		iphdr = (struct iphdr *)(skb->data + ETH_HLEN);
+		/* snoop incoming traffic for dat update using the source mac
+		 * and source ip to speed up dat.
+		 */
+		batadv_dat_entry_check(bat_priv, iphdr->saddr,
+				       ethhdr->h_source, vid);
+		break;
 	case ETH_P_8021Q:
 		vhdr = (struct vlan_ethhdr *)skb->data;

-		if (vhdr->h_vlan_encapsulated_proto != ethertype)
+		if (vhdr->h_vlan_encapsulated_proto != ethertype) {
+			/* snoop incoming traffic for dat update also for vlan
+			 * tagged frames.
+			 */
+			if (vhdr->h_vlan_encapsulated_proto == ETH_P_IP) {
+				iphdr = (struct iphdr *)(vhdr +
+						sizeof(struct vlan_ethhdr));
+				batadv_dat_entry_check(bat_priv, iphdr->saddr,
+						       vhdr->h_source, vid);
+			}
 			break;
+		}

 		/* fall through */
 	case ETH_P_BATMAN:
--
1.7.0.4



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