[B.A.T.M.A.N.] [PATCH 1/7] batman-adv: prevent multiple ARP replies sent by gateways if dat enabled

* [B.A.T.M.A.N.] [PATCH 1/7] batman-adv: prevent multiple ARP replies sent by gateways if dat enabled
@ 2016-02-25  6:28 Andreas Pape
  2016-02-25 10:30 ` Sven Eckelmann
       [not found] ` <4170150.MY2kasJMNI-2016-02-25-13-51-36@bentobox>
  0 siblings, 2 replies; 4+ messages in thread
From: Andreas Pape @ 2016-02-25  6:28 UTC (permalink / raw)
  To: b.a.t.m.a.n

This patch makes sure that only the backbone gw which has claimed the
remote destination for the ARP request answers the ARP request directly
if the MAC address is known due to the local DAT table. This prevents
multiple ARP replies in a common backbone if more than one gateway
already knows the remote mac searched for in the ARP request.

Signed-off-by: Andreas Pape <apape@phoenixcontact.com>
---
 net/batman-adv/bridge_loop_avoidance.c |   59 ++++++++++++++++++++++++++++++++
 net/batman-adv/bridge_loop_avoidance.h |    8 ++++
 net/batman-adv/distributed-arp-table.c |   15 ++++++++
 3 files changed, 82 insertions(+), 0 deletions(-)

diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c
index 0a6c8b8..6c29ec2 100644
--- a/net/batman-adv/bridge_loop_avoidance.c
+++ b/net/batman-adv/bridge_loop_avoidance.c
@@ -1906,3 +1906,62 @@ out:
 		batadv_hardif_put(primary_if);
 	return 0;
 }
+
+/**
+ * batadv_bla_handle_local_claim
+ * @bat_priv: the bat priv with all the soft interface information
+ * @addr: mac address of which the claim status is checked
+ * @vid: the VLAN ID
+ *
+ * addr is checked if this address is claimed by the local device itself.
+ * If the address is not claimed at all, claim it.
+ *
+ * Return: true if bla is disabled or the mac is claimed by the device,
+ * false if the device addr is already claimed by another gateway
+ */
+bool batadv_bla_handle_local_claim(struct batadv_priv *bat_priv, uint8_t *addr,
+		unsigned short vid)
+{
+	struct batadv_bla_claim search_claim;
+	struct batadv_bla_claim *claim = NULL;
+	struct batadv_hard_iface *primary_if = NULL;
+	bool ret = true;
+
+	if (!atomic_read(&bat_priv->bridge_loop_avoidance))
+		return ret;
+
+	primary_if = batadv_primary_if_get_selected(bat_priv);
+	if (!primary_if)
+		goto out;
+
+	/* First look if the mac address is claimed */
+	ether_addr_copy(search_claim.addr, addr);
+	search_claim.vid = vid;
+
+	claim = batadv_claim_hash_find(bat_priv,
+			  &search_claim);
+
+	/* If there is a claim and we are not owner of the claim,
+	 * return false;
+	 */
+	if (claim) {
+		if (!batadv_compare_eth(claim->backbone_gw->orig,
+				primary_if->net_dev->dev_addr))
+			ret = false;
+	} else {
+		/* If there is no claim, claim the device */
+		batadv_dbg(BATADV_DBG_BLA, bat_priv,
+				"Handle claim locally for currently not claimed mac %pM.\n",
+				search_claim.addr);
+
+		batadv_handle_claim(bat_priv, primary_if,
+				primary_if->net_dev->dev_addr, addr, vid);
+	}
+
+out:
+	if (claim)
+		batadv_claim_put(claim);
+	if (primary_if)
+		batadv_hardif_put(primary_if);
+	return ret;
+}
diff --git a/net/batman-adv/bridge_loop_avoidance.h b/net/batman-adv/bridge_loop_avoidance.h
index 579f0fa..c6d498b 100644
--- a/net/batman-adv/bridge_loop_avoidance.h
+++ b/net/batman-adv/bridge_loop_avoidance.h
@@ -46,6 +46,8 @@ void batadv_bla_update_orig_address(struct batadv_priv *bat_priv,
 void batadv_bla_status_update(struct net_device *net_dev);
 int batadv_bla_init(struct batadv_priv *bat_priv);
 void batadv_bla_free(struct batadv_priv *bat_priv);
+bool batadv_bla_handle_local_claim(struct batadv_priv *bat_priv, u8 *addr,
+		unsigned short vid);

 #define BATADV_BLA_CRC_INIT	0
 #else /* ifdef CONFIG_BATMAN_ADV_BLA */
@@ -111,6 +113,12 @@ static inline void batadv_bla_free(struct batadv_priv *bat_priv)
 {
 }

+bool batadv_bla_handle_local_claim(struct batadv_priv *bat_priv, u8 *addr,
+		unsigned short vid)
+{
+	return true;
+}
+
 #endif /* ifdef CONFIG_BATMAN_ADV_BLA */

 #endif /* ifndef _NET_BATMAN_ADV_BLA_H_ */
diff --git a/net/batman-adv/distributed-arp-table.c b/net/batman-adv/distributed-arp-table.c
index e96d7c7..aab9548 100644
--- a/net/batman-adv/distributed-arp-table.c
+++ b/net/batman-adv/distributed-arp-table.c
@@ -48,6 +48,7 @@
 #include "originator.h"
 #include "send.h"
 #include "translation-table.h"
+#include "bridge_loop_avoidance.h"

 static void batadv_dat_purge(struct work_struct *work);

@@ -1000,6 +1001,20 @@ bool batadv_dat_snoop_outgoing_arp_request(struct batadv_priv *bat_priv,
 			goto out;
 		}

+		/* If BLA is enabled, only send ARP replies if we have claimed
+		 * the destination for the ARP request or if no one else of
+		 * the backbone gws belonging to our backbone has claimed the
+		 * destination.
+		 */
+		if (!batadv_bla_handle_local_claim(bat_priv,
+				dat_entry->mac_addr, vid)) {
+			batadv_dbg(BATADV_DBG_DAT, bat_priv,
+				"Device %pM claimed by another backbone gw. Don't send ARP reply!",
+				dat_entry->mac_addr);
+			ret = true;
+			goto out;
+		}
+
 		skb_new = arp_create(ARPOP_REPLY, ETH_P_ARP, ip_src,
 				     bat_priv->soft_iface, ip_dst, hw_src,
 				     dat_entry->mac_addr, hw_src);
--
1.7.0.4



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