[B.A.T.M.A.N.] [PATCH v4 2/6] batman-adv: speed up dat by snooping received ip traffic

Andreas Pape
2016-05-12T06:31:33Z

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 | 50 ++++++++++++++++++++++++++++++++
net/batman-adv/distributed-arp-table.h | 9 +++++-
net/batman-adv/soft-interface.c | 3 ++
3 files changed, 61 insertions(+), 1 deletions(-)

diff --git a/net/batman-adv/distributed-arp-table.c b/net/batman-adv/distributed-arp-table.c
index c11f035..309daf1 100644
--- a/net/batman-adv/distributed-arp-table.c
+++ b/net/batman-adv/distributed-arp-table.c
@@ -27,6 +27,7 @@
#include <linux/if_arp.h>
#include <linux/if_ether.h>
#include <linux/if_vlan.h>
+#include <linux/ip.h>
#include <linux/in.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
@@ -362,6 +363,55 @@ 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
+ * @skb: socket buffer
+ * @vid: VLAN identifier
+ *
+ * snoops incoming socket buffer for dat cache updates, if dat is enabled.
+ * Can be called from other modules.
+ */
+void batadv_dat_entry_check(struct batadv_priv *bat_priv, struct sk_buff *skb,
+ unsigned short vid)
+{
+ struct vlan_ethhdr *vhdr = NULL, tmp_vhdr;
+ struct ethhdr *ethhdr = NULL;
+ struct iphdr *iphdr = NULL, tmp_iphdr;
+
+ if (!atomic_read(&bat_priv->distributed_arp_table))
+ return;
+
+ ethhdr = eth_hdr(skb);
+
+ switch (ntohs(ethhdr->h_proto)) {
+ case ETH_P_IP:
+ iphdr = skb_header_pointer(skb, ETH_HLEN, sizeof(tmp_iphdr),
+ &tmp_iphdr);
+ break;
+ case ETH_P_8021Q:
+ vhdr = skb_header_pointer(skb, 0, sizeof(tmp_vhdr),
+ &tmp_vhdr);
+ if (!vhdr)
+ return;
+ if (ntohs(vhdr->h_vlan_encapsulated_proto) != ETH_P_IP)
+ return;
+ iphdr = skb_header_pointer(skb, sizeof(tmp_vhdr),
+ sizeof(tmp_iphdr),
+ &tmp_iphdr);
+ break;
+ }
+
+ if (!iphdr)
+ return;
+
+ batadv_dbg(BATADV_DBG_DAT, bat_priv,
+ "Snooped IP address: %pI4 %pM (vid: %d)\n",
+ &iphdr->saddr, ethhdr->h_source,
+ BATADV_PRINT_VID(vid));
+ batadv_dat_entry_add(bat_priv, iphdr->saddr, ethhdr->h_source, 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..cf1b93c 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, struct sk_buff *skb,
+ 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, struct sk_buff *skb,
+ 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 81665b1..a86748f 100644
--- a/net/batman-adv/soft-interface.c
+++ b/net/batman-adv/soft-interface.c
@@ -442,6 +442,9 @@ void batadv_interface_rx(struct net_device *soft_iface,
goto dropped;
}

+ /* Snoop incoming traffic for dat update */
+ batadv_dat_entry_check(bat_priv, skb, vid);
+
/* skb->dev & skb->pkt_type are set here */
skb->protocol = eth_type_trans(skb, soft_iface);