batman-adv: prevent multiple ARP replies sent by gateways if dat enabled

If dat is enabled it must be made 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>
Acked-by: Simon Wunderlich <sw@simonwunderlich.de>
[sven@narfation.org: fix conflicts with current version]
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>

1 files changed, 49 insertions, 0 deletions

diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c
index 7332d284b0fc..546e66ecfabd 100644
--- a/net/batman-adv/bridge_loop_avoidance.c
+++ b/net/batman-adv/bridge_loop_avoidance.c
@@ -2449,3 +2449,52 @@ out:
 
 	return ret;
 }
+
+#ifdef CONFIG_BATMAN_ADV_DAT
+/**
+ * batadv_bla_check_claim - check if address is claimed
+ *
+ * @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.
+ *
+ * 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_check_claim(struct batadv_priv *bat_priv,
+			    u8 *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)
+		return ret;
+
+	/* 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;
+		batadv_claim_put(claim);
+	}
+
+	batadv_hardif_put(primary_if);
+	return ret;
+}
+#endif