Gratuitous ARP packet handling

[vpp.git] / src / vnet / ethernet / arp.c

diff --git a/src/vnet/ethernet/arp.c b/src/vnet/ethernet/arp.c
index 682bc2a..37e3e88 100644 (file)
--- a/src/vnet/ethernet/arp.c
+++ b/src/vnet/ethernet/arp.c
@@ -864,6 +864,7 @@ typedef enum
   _ (l3_type_not_ip4, "L3 type not IP4")                               \
   _ (l3_src_address_not_local, "IP4 source address not local to subnet") \
   _ (l3_dst_address_not_local, "IP4 destination address not local to subnet") \
+  _ (l3_dst_address_unset, "IP4 destination address is unset")          \
   _ (l3_src_address_is_local, "IP4 source address matches local interface") \
   _ (l3_src_address_learned, "ARP request IP4 source address learned")  \
   _ (replies_received, "ARP replies received")                         \
@@ -980,6 +981,9 @@ arp_input (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
            (arp0->l3_type !=
             clib_net_to_host_u16 (ETHERNET_TYPE_IP4) ?
             ETHERNET_ARP_ERROR_l3_type_not_ip4 : error0);
+         error0 =
+           (0 == arp0->ip4_over_ethernet[0].ip4.as_u32 ?
+            ETHERNET_ARP_ERROR_l3_dst_address_unset : error0);
 
          sw_if_index0 = vnet_buffer (p0)->sw_if_index[VLIB_RX];
 
@@ -1110,7 +1114,23 @@ arp_input (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
              }
          }
 
-         if (!(FIB_ENTRY_FLAG_CONNECTED & dst_flags))
+         if (fib_entry_is_sourced (dst_fei, FIB_SOURCE_ADJ))
+           {
+             /*
+              * We matched an adj-fib on ths source subnet (a /32 previously
+              * added as a result of ARP). If this request is a gratuitous
+              * ARP, then learn from it.
+              * The check for matching an adj-fib, is to prevent hosts
+              * from spamming us with gratuitous ARPS that might otherwise
+              * blow our ARP cache
+              */
+             if (arp0->ip4_over_ethernet[0].ip4.as_u32 ==
+                 arp0->ip4_over_ethernet[1].ip4.as_u32)
+               error0 = arp_learn (vnm, am, sw_if_index0,
+                                   &arp0->ip4_over_ethernet[0]);
+             goto drop2;
+           }
+         else if (!(FIB_ENTRY_FLAG_CONNECTED & dst_flags))
            {
              error0 = ETHERNET_ARP_ERROR_l3_dst_address_not_local;
              goto drop1;
@@ -1152,11 +1172,17 @@ arp_input (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
          /* Learn or update sender's mapping only for replies to addresses
           * that are local to the subnet */
          if (arp0->opcode ==
-             clib_host_to_net_u16 (ETHERNET_ARP_OPCODE_reply) &&
-             dst_is_local0)
+             clib_host_to_net_u16 (ETHERNET_ARP_OPCODE_reply))
            {
-             error0 = arp_learn (vnm, am, sw_if_index0,
-                                 &arp0->ip4_over_ethernet[0]);
+             if (dst_is_local0)
+               error0 = arp_learn (vnm, am, sw_if_index0,
+                                   &arp0->ip4_over_ethernet[0]);
+             else
+               /* a reply for a non-local destination could be a GARP.
+                * GARPs for hosts we know were handled above, so this one
+                * we drop */
+               error0 = ETHERNET_ARP_ERROR_l3_dst_address_not_local;
+
              goto drop1;
            }
          else if (arp0->opcode ==
@@ -1227,9 +1253,8 @@ arp_input (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
          continue;
 
        drop1:
-         if (0 == arp0->ip4_over_ethernet[0].ip4.as_u32 ||
-             (arp0->ip4_over_ethernet[0].ip4.as_u32 ==
-              arp0->ip4_over_ethernet[1].ip4.as_u32))
+         if (arp0->ip4_over_ethernet[0].ip4.as_u32 ==
+             arp0->ip4_over_ethernet[1].ip4.as_u32)
            {
              error0 = ETHERNET_ARP_ERROR_gratuitous_arp;
              goto drop2;