selftests: forwarding: Add a test case for ARP decapsulation

Verify that ARP packets are correctly decapsulated by the ingress VTEP
by removing the neighbours configured on both VLAN interfaces and
running a ping test.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reviewed-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/net/forwarding/vxlan_asymmetric.sh

@@ -93,6 +93,7 @@
 
 ALL_TESTS="
 	ping_ipv4
+	arp_decap
 "
 NUM_NETIFS=6
 source lib.sh
@@ -465,6 +466,23 @@ ping_ipv4()
 	ping_test $h2 10.1.1.102 ": local->remote vid 20->vid 10"
 }
 
+arp_decap()
+{
+	# Repeat the ping tests, but without populating the neighbours. This
+	# makes sure we correctly decapsulate ARP packets
+	log_info "deleting neighbours from vlan interfaces"
+
+	ip neigh del 10.1.1.102 dev vlan10
+	ip neigh del 10.1.2.102 dev vlan20
+
+	ping_ipv4
+
+	ip neigh replace 10.1.1.102 lladdr $(in_ns ns1 mac_get w2) nud noarp \
+		dev vlan10 extern_learn
+	ip neigh replace 10.1.2.102 lladdr $(in_ns ns1 mac_get w4) nud noarp \
+		dev vlan20 extern_learn
+}
+
 trap cleanup EXIT
 
 setup_prepare