Support proxy ARP on mirrored TAP interfaces

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

diff --git a/src/vnet/ethernet/arp.c b/src/vnet/ethernet/arp.c
index 4d9edaf..c84ff47 100644 (file)
--- a/src/vnet/ethernet/arp.c
+++ b/src/vnet/ethernet/arp.c
@@ -588,7 +588,7 @@ vnet_arp_set_ip4_over_ethernet_internal (vnet_main_t * vnm,
          e->fib_entry_index =
            fib_table_entry_path_add (fib_index, &pfx, FIB_SOURCE_ADJ,
                                      FIB_ENTRY_FLAG_ATTACHED,
-                                     FIB_PROTOCOL_IP4, &pfx.fp_addr,
+                                     DPO_PROTO_IP4, &pfx.fp_addr,
                                      e->sw_if_index, ~0, 1, NULL,
                                      FIB_ROUTE_PATH_FLAG_NONE);
        }
@@ -787,7 +787,6 @@ typedef enum
   _ (opcode_not_request, "ARP opcode not request")                      \
   _ (proxy_arp_replies_sent, "Proxy ARP replies sent")                 \
   _ (l2_address_mismatch, "ARP hw addr does not match L2 frame src addr") \
-  _ (missing_interface_address, "ARP missing interface address") \
   _ (gratuitous_arp, "ARP probe or announcement dropped") \
   _ (interface_no_table, "Interface is not mapped to an IP table") \
   _ (interface_not_ip_enabled, "Interface is not IP enabled") \
@@ -906,8 +905,7 @@ arp_input (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
          fib_node_index_t dst_fei, src_fei;
          fib_prefix_t pfx0;
          fib_entry_flag_t src_flags, dst_flags;
-         ip_adjacency_t *adj0 = NULL;
-         adj_index_t ai;
+         u8 *rewrite0, rewrite0_len;
 
          pi0 = from[0];
          to_next[0] = pi0;
@@ -1006,7 +1004,17 @@ arp_input (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
                   if (FIB_ENTRY_FLAG_LOCAL & src_flags)
                     {
                       error0 = ETHERNET_ARP_ERROR_l3_src_address_is_local;
-                      goto drop2;
+                      /*
+                       * When VPP has an interface whose address is also
+                       * applied to a TAP interface on the host, then VPP's
+                       * TAP interface will be unnumbered  to the 'real'
+                       * interface and do proxy ARP from the host.
+                       * The curious aspect of this setup is that ARP requests
+                       * from the host will come from the VPP's own address.
+                       * So don't drop immediately here, instead go see if this
+                       * is a proxy ARP case.
+                       */
+                      goto drop1;
                     }
                   /* A Source must also be local to subnet of matching
                    * interface address. */
@@ -1105,20 +1113,18 @@ arp_input (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
              goto drop1;
            }
 
-         /* Send a reply. */
        send_reply:
-         ai = fib_entry_get_adj (src_fei);
-         if (ADJ_INDEX_INVALID != ai)
-           {
-             adj0 = adj_get (ai);
-           }
-         else
-           {
-             error0 = ETHERNET_ARP_ERROR_missing_interface_address;
-             goto drop2;
-           }
+         /* Send a reply.
+            An adjacency to the sender is not always present,
+            so we use the interface to build us a rewrite string
+            which will contain all the necessary tags. */
+         rewrite0 = ethernet_build_rewrite (vnm, sw_if_index0,
+                                            VNET_LINK_ARP,
+                                            eth_rx->src_address);
+         rewrite0_len = vec_len (rewrite0);
+
          /* Figure out how much to rewind current data from adjacency. */
-         vlib_buffer_advance (p0, -adj0->rewrite_header.data_bytes);
+         vlib_buffer_advance (p0, -rewrite0_len);
          eth_tx = vlib_buffer_get_current (p0);
 
          vnet_buffer (p0)->sw_if_index[VLIB_TX] = sw_if_index0;
@@ -1143,8 +1149,8 @@ arp_input (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
          /* the rx nd tx ethernet headers wil overlap in the case
           * when we received a tagged VLAN=0 packet, but we are sending
           * back untagged */
-         memmove (eth_tx->dst_address, eth_rx->src_address, 6);
-         clib_memcpy (eth_tx->src_address, hw_if0->hw_address, 6);
+         clib_memcpy (eth_tx, rewrite0, vec_len (rewrite0));
+         vec_free (rewrite0);
 
          if (NULL == pa)
            {
@@ -1155,9 +1161,11 @@ arp_input (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
                }
            }
 
-         /* We are going to reply to this request, so learn the sender */
-         error0 = arp_learn (vnm, am, sw_if_index0,
-                             &arp0->ip4_over_ethernet[1]);
+         /* We are going to reply to this request, so, in the absence of
+            errors, learn the sender */
+         if (!error0)
+           error0 = arp_learn (vnm, am, sw_if_index0,
+                               &arp0->ip4_over_ethernet[1]);
 
          vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
                                           n_left_to_next, pi0, next0);
@@ -1621,7 +1629,7 @@ arp_entry_free (ethernet_arp_interface_t * eai, ethernet_arp_ip4_entry_t * e)
 
       fib_table_entry_path_remove (fib_index, &pfx,
                                   FIB_SOURCE_ADJ,
-                                  FIB_PROTOCOL_IP4,
+                                  DPO_PROTO_IP4,
                                   &pfx.fp_addr,
                                   e->sw_if_index, ~0, 1,
                                   FIB_ROUTE_PATH_FLAG_NONE);
@@ -1639,6 +1647,9 @@ vnet_arp_unset_ip4_over_ethernet_internal (vnet_main_t * vnm,
   ethernet_arp_ip4_entry_t *e;
   ethernet_arp_interface_t *eai;
 
+  if (vec_len (am->ethernet_arp_by_sw_if_index) <= args->sw_if_index)
+    return 0;
+
   eai = &am->ethernet_arp_by_sw_if_index[args->sw_if_index];
 
   e = arp_entry_find (eai, &args->a.ip4);
@@ -1663,6 +1674,9 @@ vnet_arp_flush_ip4_over_ethernet_internal (vnet_main_t * vnm,
   ethernet_arp_ip4_entry_t *e;
   ethernet_arp_interface_t *eai;
 
+  if (vec_len (am->ethernet_arp_by_sw_if_index) <= args->sw_if_index)
+    return 0;
+
   eai = &am->ethernet_arp_by_sw_if_index[args->sw_if_index];
 
   e = arp_entry_find (eai, &args->a.ip4);
@@ -1696,6 +1710,7 @@ vnet_arp_populate_ip4_over_ethernet_internal (vnet_main_t * vnm,
   ethernet_arp_ip4_entry_t *e;
   ethernet_arp_interface_t *eai;
 
+  vec_validate (am->ethernet_arp_by_sw_if_index, args->sw_if_index);
   eai = &am->ethernet_arp_by_sw_if_index[args->sw_if_index];
 
   e = arp_entry_find (eai, &args->a.ip4);