text: /*
   * Copyright (c) 2015 Cisco and/or its affiliates.
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at:
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  /*
   * ip/ip4_forward.c: IP v4 forwarding
   *
   * Copyright (c) 2008 Eliot Dresselhaus
   *
   * Permission is hereby granted, free of charge, to any person obtaining
   * a copy of this software and associated documentation files (the
   * "Software"), to deal in the Software without restriction, including
   * without limitation the rights to use, copy, modify, merge, publish,
   * distribute, sublicense, and/or sell copies of the Software, and to
   * permit persons to whom the Software is furnished to do so, subject to
   * the following conditions:
   *
   * The above copyright notice and this permission notice shall be
   * included in all copies or substantial portions of the Software.
   *
   *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
   *  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   *  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
   *  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
   *  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   *  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
   *  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   */
  
  #include <vnet/vnet.h>
  #include <vnet/ip/ip.h>
  #include <vnet/ethernet/ethernet.h>	/* for ethernet_header_t */
  #include <vnet/ethernet/arp_packet.h>	/* for ethernet_arp_header_t */
  #include <vnet/ppp/ppp.h>
  #include <vnet/srp/srp.h>	/* for srp_hw_interface_class */
  #include <vnet/api_errno.h>	/* for API error numbers */
  #include <vnet/fib/fib_table.h>	/* for FIB table and entry creation */
  #include <vnet/fib/fib_entry.h>	/* for FIB table and entry creation */
  #include <vnet/fib/fib_urpf_list.h>	/* for FIB uRPF check */
  #include <vnet/fib/ip4_fib.h>
  #include <vnet/dpo/load_balance.h>
  #include <vnet/dpo/classify_dpo.h>
  #include <vnet/mfib/mfib_table.h>	/* for mFIB table and entry creation */
  
  /**
   * @file
   * @brief IPv4 Forwarding.
   *
   * This file contains the source code for IPv4 forwarding.
   */
  
  void
  ip4_forward_next_trace (vlib_main_t * vm,
  			vlib_node_runtime_t * node,
  			vlib_frame_t * frame,
  			vlib_rx_or_tx_t which_adj_index);
  
  always_inline uword
  ip4_lookup_inline (vlib_main_t * vm,
  		   vlib_node_runtime_t * node,
  		   vlib_frame_t * frame,
  		   int lookup_for_responses_to_locally_received_packets)
  {
    ip4_main_t *im = &ip4_main;
    vlib_combined_counter_main_t *cm = &load_balance_main.lbm_to_counters;
    u32 n_left_from, n_left_to_next, *from, *to_next;
    ip_lookup_next_t next;
    u32 cpu_index = os_get_cpu_number ();
  
    from = vlib_frame_vector_args (frame);
    n_left_from = frame->n_vectors;
    next = node->cached_next_index;
  
    while (n_left_from > 0)
      {
        vlib_get_next_frame (vm, node, next, to_next, n_left_to_next);
  
        while (n_left_from >= 8 && n_left_to_next >= 4)
  	{
  	  vlib_buffer_t *p0, *p1, *p2, *p3;
  	  ip4_header_t *ip0, *ip1, *ip2, *ip3;
  	  __attribute__ ((unused)) tcp_header_t *tcp0, *tcp1, *tcp2, *tcp3;
  	  ip_lookup_next_t next0, next1, next2, next3;
  	  const load_balance_t *lb0, *lb1, *lb2, *lb3;
  	  ip4_fib_mtrie_t *mtrie0, *mtrie1, *mtrie2, *mtrie3;
  	  ip4_fib_mtrie_leaf_t leaf0, leaf1, leaf2, leaf3;
  	  ip4_address_t *dst_addr0, *dst_addr1, *dst_addr2, *dst_addr3;
  	  __attribute__ ((unused)) u32 pi0, fib_index0, lb_index0,
  	    is_tcp_udp0;
  	  __attribute__ ((unused)) u32 pi1, fib_index1, lb_index1,
  	    is_tcp_udp1;
  	  __attribute__ ((unused)) u32 pi2, fib_index2, lb_index2,
  	    is_tcp_udp2;
  	  __attribute__ ((unused)) u32 pi3, fib_index3, lb_index3,
  	    is_tcp_udp3;
  	  flow_hash_config_t flow_hash_config0, flow_hash_config1;
  	  flow_hash_config_t flow_hash_config2, flow_hash_config3;
  	  u32 hash_c0, hash_c1, hash_c2, hash_c3;
  	  const dpo_id_t *dpo0, *dpo1, *dpo2, *dpo3;
  
  	  /* Prefetch next iteration. */
  	  {
  	    vlib_buffer_t *p4, *p5, *p6, *p7;
  
  	    p4 = vlib_get_buffer (vm, from[4]);
  	    p5 = vlib_get_buffer (vm, from[5]);
  	    p6 = vlib_get_buffer (vm, from[6]);
  	    p7 = vlib_get_buffer (vm, from[7]);
  
  	    vlib_prefetch_buffer_header (p4, LOAD);
  	    vlib_prefetch_buffer_header (p5, LOAD);
  	    vlib_prefetch_buffer_header (p6, LOAD);
  	    vlib_prefetch_buffer_header (p7, LOAD);
  
  	    CLIB_PREFETCH (p4->data, sizeof (ip0[0]), LOAD);
  	    CLIB_PREFETCH (p5->data, sizeof (ip0[0]), LOAD);
  	    CLIB_PREFETCH (p6->data, sizeof (ip0[0]), LOAD);
  	    CLIB_PREFETCH (p7->data, sizeof (ip0[0]), LOAD);
  	  }
  
  	  pi0 = to_next[0] = from[0];
  	  pi1 = to_next[1] = from[1];
  	  pi2 = to_next[2] = from[2];
  	  pi3 = to_next[3] = from[3];
  
  	  from += 4;
  	  to_next += 4;
  	  n_left_to_next -= 4;
  	  n_left_from -= 4;
  
  	  p0 = vlib_get_buffer (vm, pi0);
  	  p1 = vlib_get_buffer (vm, pi1);
  	  p2 = vlib_get_buffer (vm, pi2);
  	  p3 = vlib_get_buffer (vm, pi3);
  
  	  ip0 = vlib_buffer_get_current (p0);
  	  ip1 = vlib_buffer_get_current (p1);
  	  ip2 = vlib_buffer_get_current (p2);
  	  ip3 = vlib_buffer_get_current (p3);
  
  	  dst_addr0 = &ip0->dst_address;
  	  dst_addr1 = &ip1->dst_address;
  	  dst_addr2 = &ip2->dst_address;
  	  dst_addr3 = &ip3->dst_address;
  
  	  fib_index0 =
  	    vec_elt (im->fib_index_by_sw_if_index,
  		     vnet_buffer (p0)->sw_if_index[VLIB_RX]);
  	  fib_index1 =
  	    vec_elt (im->fib_index_by_sw_if_index,
  		     vnet_buffer (p1)->sw_if_index[VLIB_RX]);
  	  fib_index2 =
  	    vec_elt (im->fib_index_by_sw_if_index,
  		     vnet_buffer (p2)->sw_if_index[VLIB_RX]);
  	  fib_index3 =
  	    vec_elt (im->fib_index_by_sw_if_index,
  		     vnet_buffer (p3)->sw_if_index[VLIB_RX]);
  	  fib_index0 =
  	    (vnet_buffer (p0)->sw_if_index[VLIB_TX] ==
  	     (u32) ~ 0) ? fib_index0 : vnet_buffer (p0)->sw_if_index[VLIB_TX];
  	  fib_index1 =
  	    (vnet_buffer (p1)->sw_if_index[VLIB_TX] ==
  	     (u32) ~ 0) ? fib_index1 : vnet_buffer (p1)->sw_if_index[VLIB_TX];
  	  fib_index2 =
  	    (vnet_buffer (p2)->sw_if_index[VLIB_TX] ==
  	     (u32) ~ 0) ? fib_index2 : vnet_buffer (p2)->sw_if_index[VLIB_TX];
  	  fib_index3 =
  	    (vnet_buffer (p3)->sw_if_index[VLIB_TX] ==
  	     (u32) ~ 0) ? fib_index3 : vnet_buffer (p3)->sw_if_index[VLIB_TX];
  
  
  	  if (!lookup_for_responses_to_locally_received_packets)
  	    {
  	      mtrie0 = &ip4_fib_get (fib_index0)->mtrie;
  	      mtrie1 = &ip4_fib_get (fib_index1)->mtrie;
  	      mtrie2 = &ip4_fib_get (fib_index2)->mtrie;
  	      mtrie3 = &ip4_fib_get (fib_index3)->mtrie;
  
  	      leaf0 = leaf1 = leaf2 = leaf3 = IP4_FIB_MTRIE_LEAF_ROOT;
  
  	      leaf0 = ip4_fib_mtrie_lookup_step (mtrie0, leaf0, dst_addr0, 0);
  	      leaf1 = ip4_fib_mtrie_lookup_step (mtrie1, leaf1, dst_addr1, 0);
  	      leaf2 = ip4_fib_mtrie_lookup_step (mtrie2, leaf2, dst_addr2, 0);
  	      leaf3 = ip4_fib_mtrie_lookup_step (mtrie3, leaf3, dst_addr3, 0);
  	    }
  
  	  tcp0 = (void *) (ip0 + 1);
  	  tcp1 = (void *) (ip1 + 1);
  	  tcp2 = (void *) (ip2 + 1);
  	  tcp3 = (void *) (ip3 + 1);
  
  	  is_tcp_udp0 = (ip0->protocol == IP_PROTOCOL_TCP
  			 || ip0->protocol == IP_PROTOCOL_UDP);
  	  is_tcp_udp1 = (ip1->protocol == IP_PROTOCOL_TCP
  			 || ip1->protocol == IP_PROTOCOL_UDP);
  	  is_tcp_udp2 = (ip2->protocol == IP_PROTOCOL_TCP
  			 || ip2->protocol == IP_PROTOCOL_UDP);
  	  is_tcp_udp3 = (ip1->protocol == IP_PROTOCOL_TCP
  			 || ip1->protocol == IP_PROTOCOL_UDP);
  
  	  if (!lookup_for_responses_to_locally_received_packets)
  	    {
  	      leaf0 = ip4_fib_mtrie_lookup_step (mtrie0, leaf0, dst_addr0, 1);
  	      leaf1 = ip4_fib_mtrie_lookup_step (mtrie1, leaf1, dst_addr1, 1);
  	      leaf2 = ip4_fib_mtrie_lookup_step (mtrie2, leaf2, dst_addr2, 1);
  	      leaf3 = ip4_fib_mtrie_lookup_step (mtrie3, leaf3, dst_addr3, 1);
  	    }
  
  	  if (!lookup_for_responses_to_locally_received_packets)
  	    {
  	      leaf0 = ip4_fib_mtrie_lookup_step (mtrie0, leaf0, dst_addr0, 2);
  	      leaf1 = ip4_fib_mtrie_lookup_step (mtrie1, leaf1, dst_addr1, 2);
  	      leaf2 = ip4_fib_mtrie_lookup_step (mtrie2, leaf2, dst_addr2, 2);
  	      leaf3 = ip4_fib_mtrie_lookup_step (mtrie3, leaf3, dst_addr3, 2);
  	    }
  
  	  if (!lookup_for_responses_to_locally_received_packets)
  	    {
  	      leaf0 = ip4_fib_mtrie_lookup_step (mtrie0, leaf0, dst_addr0, 3);
  	      leaf1 = ip4_fib_mtrie_lookup_step (mtrie1, leaf1, dst_addr1, 3);
  	      leaf2 = ip4_fib_mtrie_lookup_step (mtrie2, leaf2, dst_addr2, 3);
  	      leaf3 = ip4_fib_mtrie_lookup_step (mtrie3, leaf3, dst_addr3, 3);
  	    }
  
  	  if (lookup_for_responses_to_locally_received_packets)
  	    {
  	      lb_index0 = vnet_buffer (p0)->ip.adj_index[VLIB_RX];
  	      lb_index1 = vnet_buffer (p1)->ip.adj_index[VLIB_RX];
  	      lb_index2 = vnet_buffer (p2)->ip.adj_index[VLIB_RX];
  	      lb_index3 = vnet_buffer (p3)->ip.adj_index[VLIB_RX];
  	    }
  	  else
  	    {
  	      /* Handle default route. */
  	      leaf0 =
  		(leaf0 ==
  		 IP4_FIB_MTRIE_LEAF_EMPTY ? mtrie0->default_leaf : leaf0);
  	      leaf1 =
  		(leaf1 ==
  		 IP4_FIB_MTRIE_LEAF_EMPTY ? mtrie1->default_leaf : leaf1);
  	      leaf2 =
  		(leaf2 ==
  		 IP4_FIB_MTRIE_LEAF_EMPTY ? mtrie2->default_leaf : leaf2);
  	      leaf3 =
  		(leaf3 ==
  		 IP4_FIB_MTRIE_LEAF_EMPTY ? mtrie3->default_leaf : leaf3);
  	      lb_index0 = ip4_fib_mtrie_leaf_get_adj_index (leaf0);
  	      lb_index1 = ip4_fib_mtrie_leaf_get_adj_index (leaf1);
  	      lb_index2 = ip4_fib_mtrie_leaf_get_adj_index (leaf2);
  	      lb_index3 = ip4_fib_mtrie_leaf_get_adj_index (leaf3);
  	    }
  
  	  lb0 = load_balance_get (lb_index0);
  	  lb1 = load_balance_get (lb_index1);
  	  lb2 = load_balance_get (lb_index2);
  	  lb3 = load_balance_get (lb_index3);
  
  	  /* Use flow hash to compute multipath adjacency. */
  	  hash_c0 = vnet_buffer (p0)->ip.flow_hash = 0;
  	  hash_c1 = vnet_buffer (p1)->ip.flow_hash = 0;
  	  hash_c2 = vnet_buffer (p2)->ip.flow_hash = 0;
  	  hash_c3 = vnet_buffer (p3)->ip.flow_hash = 0;
  	  if (PREDICT_FALSE (lb0->lb_n_buckets > 1))
  	    {
  	      flow_hash_config0 = lb0->lb_hash_config;
  	      hash_c0 = vnet_buffer (p0)->ip.flow_hash =
  		ip4_compute_flow_hash (ip0, flow_hash_config0);
  	    }
  	  if (PREDICT_FALSE (lb1->lb_n_buckets > 1))
  	    {
  	      flow_hash_config1 = lb1->lb_hash_config;
  	      hash_c1 = vnet_buffer (p1)->ip.flow_hash =
  		ip4_compute_flow_hash (ip1, flow_hash_config1);
  	    }
  	  if (PREDICT_FALSE (lb2->lb_n_buckets > 1))
  	    {
  	      flow_hash_config2 = lb2->lb_hash_config;
  	      hash_c2 = vnet_buffer (p2)->ip.flow_hash =
  		ip4_compute_flow_hash (ip2, flow_hash_config2);
  	    }
  	  if (PREDICT_FALSE (lb3->lb_n_buckets > 1))
  	    {
  	      flow_hash_config3 = lb3->lb_hash_config;
  	      hash_c3 = vnet_buffer (p3)->ip.flow_hash =
  		ip4_compute_flow_hash (ip3, flow_hash_config3);
  	    }
  
  	  ASSERT (lb0->lb_n_buckets > 0);
  	  ASSERT (is_pow2 (lb0->lb_n_buckets));
  	  ASSERT (lb1->lb_n_buckets > 0);
  	  ASSERT (is_pow2 (lb1->lb_n_buckets));
  	  ASSERT (lb2->lb_n_buckets > 0);
  	  ASSERT (is_pow2 (lb2->lb_n_buckets));
  	  ASSERT (lb3->lb_n_buckets > 0);
  	  ASSERT (is_pow2 (lb3->lb_n_buckets));
  
  	  dpo0 = load_balance_get_bucket_i (lb0,
  					    (hash_c0 &
  					     (lb0->lb_n_buckets_minus_1)));
  	  dpo1 = load_balance_get_bucket_i (lb1,
  					    (hash_c1 &
  					     (lb1->lb_n_buckets_minus_1)));
  	  dpo2 = load_balance_get_bucket_i (lb2,
  					    (hash_c2 &
  					     (lb2->lb_n_buckets_minus_1)));
  	  dpo3 = load_balance_get_bucket_i (lb3,
  					    (hash_c3 &
  					     (lb3->lb_n_buckets_minus_1)));
  
  	  next0 = dpo0->dpoi_next_node;
  	  vnet_buffer (p0)->ip.adj_index[VLIB_TX] = dpo0->dpoi_index;
  	  next1 = dpo1->dpoi_next_node;
  	  vnet_buffer (p1)->ip.adj_index[VLIB_TX] = dpo1->dpoi_index;
  	  next2 = dpo2->dpoi_next_node;
  	  vnet_buffer (p2)->ip.adj_index[VLIB_TX] = dpo2->dpoi_index;
  	  next3 = dpo3->dpoi_next_node;
  	  vnet_buffer (p3)->ip.adj_index[VLIB_TX] = dpo3->dpoi_index;
  
  	  vlib_increment_combined_counter
  	    (cm, cpu_index, lb_index0, 1,
  	     vlib_buffer_length_in_chain (vm, p0)
  	     + sizeof (ethernet_header_t));
  	  vlib_increment_combined_counter
  	    (cm, cpu_index, lb_index1, 1,
  	     vlib_buffer_length_in_chain (vm, p1)
  	     + sizeof (ethernet_header_t));
  	  vlib_increment_combined_counter
  	    (cm, cpu_index, lb_index2, 1,
  	     vlib_buffer_length_in_chain (vm, p2)
  	     + sizeof (ethernet_header_t));
  	  vlib_increment_combined_counter
  	    (cm, cpu_index, lb_index3, 1,
  	     vlib_buffer_length_in_chain (vm, p3)
  	     + sizeof (ethernet_header_t));
  
  	  vlib_validate_buffer_enqueue_x4 (vm, node, next,
  					   to_next, n_left_to_next,
  					   pi0, pi1, pi2, pi3,
  					   next0, next1, next2, next3);
  	}
  
        while (n_left_from > 0 && n_left_to_next > 0)
  	{
  	  vlib_buffer_t *p0;
  	  ip4_header_t *ip0;
  	  __attribute__ ((unused)) tcp_header_t *tcp0;
  	  ip_lookup_next_t next0;
  	  const load_balance_t *lb0;
  	  ip4_fib_mtrie_t *mtrie0;
  	  ip4_fib_mtrie_leaf_t leaf0;
  	  ip4_address_t *dst_addr0;
  	  __attribute__ ((unused)) u32 pi0, fib_index0, is_tcp_udp0, lbi0;
  	  flow_hash_config_t flow_hash_config0;
  	  const dpo_id_t *dpo0;
  	  u32 hash_c0;
  
  	  pi0 = from[0];
  	  to_next[0] = pi0;
  
  	  p0 = vlib_get_buffer (vm, pi0);
  
  	  ip0 = vlib_buffer_get_current (p0);
  
  	  dst_addr0 = &ip0->dst_address;
  
  	  fib_index0 =
  	    vec_elt (im->fib_index_by_sw_if_index,
  		     vnet_buffer (p0)->sw_if_index[VLIB_RX]);
  	  fib_index0 =
  	    (vnet_buffer (p0)->sw_if_index[VLIB_TX] ==
  	     (u32) ~ 0) ? fib_index0 : vnet_buffer (p0)->sw_if_index[VLIB_TX];
  
  	  if (!lookup_for_responses_to_locally_received_packets)
  	    {
  	      mtrie0 = &ip4_fib_get (fib_index0)->mtrie;
  
  	      leaf0 = IP4_FIB_MTRIE_LEAF_ROOT;
  
  	      leaf0 = ip4_fib_mtrie_lookup_step (mtrie0, leaf0, dst_addr0, 0);
  	    }
  
  	  tcp0 = (void *) (ip0 + 1);
  
  	  is_tcp_udp0 = (ip0->protocol == IP_PROTOCOL_TCP
  			 || ip0->protocol == IP_PROTOCOL_UDP);
  
  	  if (!lookup_for_responses_to_locally_received_packets)
  	    leaf0 = ip4_fib_mtrie_lookup_step (mtrie0, leaf0, dst_addr0, 1);
  
  	  if (!lookup_for_responses_to_locally_received_packets)
  	    leaf0 = ip4_fib_mtrie_lookup_step (mtrie0, leaf0, dst_addr0, 2);
  
  	  if (!lookup_for_responses_to_locally_received_packets)
  	    leaf0 = ip4_fib_mtrie_lookup_step (mtrie0, leaf0, dst_addr0, 3);
  
  	  if (lookup_for_responses_to_locally_received_packets)
  	    lbi0 = vnet_buffer (p0)->ip.adj_index[VLIB_RX];
  	  else
  	    {
  	      /* Handle default route. */
  	      leaf0 =
  		(leaf0 ==
  		 IP4_FIB_MTRIE_LEAF_EMPTY ? mtrie0->default_leaf : leaf0);
  	      lbi0 = ip4_fib_mtrie_leaf_get_adj_index (leaf0);
  	    }
  
  	  lb0 = load_balance_get (lbi0);
  
  	  /* Use flow hash to compute multipath adjacency. */
  	  hash_c0 = vnet_buffer (p0)->ip.flow_hash = 0;
  	  if (PREDICT_FALSE (lb0->lb_n_buckets > 1))
  	    {
  	      flow_hash_config0 = lb0->lb_hash_config;
  
  	      hash_c0 = vnet_buffer (p0)->ip.flow_hash =
  		ip4_compute_flow_hash (ip0, flow_hash_config0);
  	    }
  
  	  ASSERT (lb0->lb_n_buckets > 0);
  	  ASSERT (is_pow2 (lb0->lb_n_buckets));
  
  	  dpo0 = load_balance_get_bucket_i (lb0,
  					    (hash_c0 &
  					     (lb0->lb_n_buckets_minus_1)));
  
  	  next0 = dpo0->dpoi_next_node;
  	  vnet_buffer (p0)->ip.adj_index[VLIB_TX] = dpo0->dpoi_index;
  
  	  vlib_increment_combined_counter
  	    (cm, cpu_index, lbi0, 1, vlib_buffer_length_in_chain (vm, p0));
  
  	  from += 1;
  	  to_next += 1;
  	  n_left_to_next -= 1;
  	  n_left_from -= 1;
  
  	  if (PREDICT_FALSE (next0 != next))
  	    {
  	      n_left_to_next += 1;
  	      vlib_put_next_frame (vm, node, next, n_left_to_next);
  	      next = next0;
  	      vlib_get_next_frame (vm, node, next, to_next, n_left_to_next);
  	      to_next[0] = pi0;
  	      to_next += 1;
  	      n_left_to_next -= 1;
  	    }
  	}
  
        vlib_put_next_frame (vm, node, next, n_left_to_next);
      }
  
    if (node->flags & VLIB_NODE_FLAG_TRACE)
      ip4_forward_next_trace (vm, node, frame, VLIB_TX);
  
    return frame->n_vectors;
  }
  
  /** @brief IPv4 lookup node.
      @node ip4-lookup
  
      This is the main IPv4 lookup dispatch node.
  
      @param vm vlib_main_t corresponding to the current thread
      @param node vlib_node_runtime_t
      @param frame vlib_frame_t whose contents should be dispatched
  
      @par Graph mechanics: buffer metadata, next index usage
  
      @em Uses:
      - <code>vnet_buffer(b)->sw_if_index[VLIB_RX]</code>
          - Indicates the @c sw_if_index value of the interface that the
  	  packet was received on.
      - <code>vnet_buffer(b)->sw_if_index[VLIB_TX]</code>
          - When the value is @c ~0 then the node performs a longest prefix
            match (LPM) for the packet destination address in the FIB attached
            to the receive interface.
          - Otherwise perform LPM for the packet destination address in the
            indicated FIB. In this case <code>[VLIB_TX]</code> is a FIB index
            value (0, 1, ...) and not a VRF id.
  
      @em Sets:
      - <code>vnet_buffer(b)->ip.adj_index[VLIB_TX]</code>
          - The lookup result adjacency index.
  
      <em>Next Index:</em>
      - Dispatches the packet to the node index found in
        ip_adjacency_t @c adj->lookup_next_index
        (where @c adj is the lookup result adjacency).
  */
  static uword
  ip4_lookup (vlib_main_t * vm,
  	    vlib_node_runtime_t * node, vlib_frame_t * frame)
  {
    return ip4_lookup_inline (vm, node, frame,
  			    /* lookup_for_responses_to_locally_received_packets */
  			    0);
  
  }
  
  static u8 *format_ip4_lookup_trace (u8 * s, va_list * args);
  
  VLIB_REGISTER_NODE (ip4_lookup_node) =
  {
  .function = ip4_lookup,.name = "ip4-lookup",.vector_size =
      sizeof (u32),.format_trace = format_ip4_lookup_trace,.n_next_nodes =
      IP_LOOKUP_N_NEXT,.next_nodes = IP4_LOOKUP_NEXT_NODES,};
  
  VLIB_NODE_FUNCTION_MULTIARCH (ip4_lookup_node, ip4_lookup);
  
  always_inline uword
  ip4_load_balance (vlib_main_t * vm,
  		  vlib_node_runtime_t * node, vlib_frame_t * frame)
  {
    vlib_combined_counter_main_t *cm = &load_balance_main.lbm_via_counters;
    u32 n_left_from, n_left_to_next, *from, *to_next;
    ip_lookup_next_t next;
    u32 cpu_index = os_get_cpu_number ();
  
    from = vlib_frame_vector_args (frame);
    n_left_from = frame->n_vectors;
    next = node->cached_next_index;
  
    if (node->flags & VLIB_NODE_FLAG_TRACE)
      ip4_forward_next_trace (vm, node, frame, VLIB_TX);
  
    while (n_left_from > 0)
      {
        vlib_get_next_frame (vm, node, next, to_next, n_left_to_next);
  
  
        while (n_left_from >= 4 && n_left_to_next >= 2)
  	{
  	  ip_lookup_next_t next0, next1;
  	  const load_balance_t *lb0, *lb1;
  	  vlib_buffer_t *p0, *p1;
  	  u32 pi0, lbi0, hc0, pi1, lbi1, hc1;
  	  const ip4_header_t *ip0, *ip1;
  	  const dpo_id_t *dpo0, *dpo1;
  
  	  /* Prefetch next iteration. */
  	  {
  	    vlib_buffer_t *p2, *p3;
  
  	    p2 = vlib_get_buffer (vm, from[2]);
  	    p3 = vlib_get_buffer (vm, from[3]);
  
  	    vlib_prefetch_buffer_header (p2, STORE);
  	    vlib_prefetch_buffer_header (p3, STORE);
  
  	    CLIB_PREFETCH (p2->data, sizeof (ip0[0]), STORE);
  	    CLIB_PREFETCH (p3->data, sizeof (ip0[0]), STORE);
  	  }
  
  	  pi0 = to_next[0] = from[0];
  	  pi1 = to_next[1] = from[1];
  
  	  from += 2;
  	  n_left_from -= 2;
  	  to_next += 2;
  	  n_left_to_next -= 2;
  
  	  p0 = vlib_get_buffer (vm, pi0);
  	  p1 = vlib_get_buffer (vm, pi1);
  
  	  ip0 = vlib_buffer_get_current (p0);
  	  ip1 = vlib_buffer_get_current (p1);
  	  lbi0 = vnet_buffer (p0)->ip.adj_index[VLIB_TX];
  	  lbi1 = vnet_buffer (p1)->ip.adj_index[VLIB_TX];
  
  	  lb0 = load_balance_get (lbi0);
  	  lb1 = load_balance_get (lbi1);
  
  	  /*
  	   * this node is for via FIBs we can re-use the hash value from the
  	   * to node if present.
  	   * We don't want to use the same hash value at each level in the recursion
  	   * graph as that would lead to polarisation
  	   */
  	  hc0 = vnet_buffer (p0)->ip.flow_hash = 0;
  	  hc1 = vnet_buffer (p1)->ip.flow_hash = 0;
  
  	  if (PREDICT_FALSE (lb0->lb_n_buckets > 1))
  	    {
  	      if (PREDICT_TRUE (vnet_buffer (p0)->ip.flow_hash))
  		{
  		  hc0 = vnet_buffer (p0)->ip.flow_hash =
  		    vnet_buffer (p0)->ip.flow_hash >> 1;
  		}
  	      else
  		{
  		  hc0 = vnet_buffer (p0)->ip.flow_hash =
  		    ip4_compute_flow_hash (ip0, hc0);
  		}
  	    }
  	  if (PREDICT_FALSE (lb1->lb_n_buckets > 1))
  	    {
  	      if (PREDICT_TRUE (vnet_buffer (p1)->ip.flow_hash))
  		{
  		  hc1 = vnet_buffer (p1)->ip.flow_hash =
  		    vnet_buffer (p1)->ip.flow_hash >> 1;
  		}
  	      else
  		{
  		  hc1 = vnet_buffer (p1)->ip.flow_hash =
  		    ip4_compute_flow_hash (ip1, hc1);
  		}
  	    }
  
  	  dpo0 =
  	    load_balance_get_bucket_i (lb0,
  				       hc0 & (lb0->lb_n_buckets_minus_1));
  	  dpo1 =
  	    load_balance_get_bucket_i (lb1,
  				       hc1 & (lb1->lb_n_buckets_minus_1));
  
  	  next0 = dpo0->dpoi_next_node;
  	  next1 = dpo1->dpoi_next_node;
  
  	  vnet_buffer (p0)->ip.adj_index[VLIB_TX] = dpo0->dpoi_index;
  	  vnet_buffer (p1)->ip.adj_index[VLIB_TX] = dpo1->dpoi_index;
  
  	  vlib_increment_combined_counter
  	    (cm, cpu_index, lbi0, 1, vlib_buffer_length_in_chain (vm, p0));
  	  vlib_increment_combined_counter
  	    (cm, cpu_index, lbi1, 1, vlib_buffer_length_in_chain (vm, p1));
  
  	  vlib_validate_buffer_enqueue_x2 (vm, node, next,
  					   to_next, n_left_to_next,
  					   pi0, pi1, next0, next1);
  	}
  
        while (n_left_from > 0 && n_left_to_next > 0)
  	{
  	  ip_lookup_next_t next0;
  	  const load_balance_t *lb0;
  	  vlib_buffer_t *p0;
  	  u32 pi0, lbi0, hc0;
  	  const ip4_header_t *ip0;
  	  const dpo_id_t *dpo0;
  
  	  pi0 = from[0];
  	  to_next[0] = pi0;
  	  from += 1;
  	  to_next += 1;
  	  n_left_to_next -= 1;
  	  n_left_from -= 1;
  
  	  p0 = vlib_get_buffer (vm, pi0);
  
  	  ip0 = vlib_buffer_get_current (p0);
  	  lbi0 = vnet_buffer (p0)->ip.adj_index[VLIB_TX];
  
  	  lb0 = load_balance_get (lbi0);
  
  	  hc0 = vnet_buffer (p0)->ip.flow_hash = 0;
  	  if (PREDICT_FALSE (lb0->lb_n_buckets > 1))
  	    {
  	      if (PREDICT_TRUE (vnet_buffer (p0)->ip.flow_hash))
  		{
  		  hc0 = vnet_buffer (p0)->ip.flow_hash =
  		    vnet_buffer (p0)->ip.flow_hash >> 1;
  		}
  	      else
  		{
  		  hc0 = vnet_buffer (p0)->ip.flow_hash =
  		    ip4_compute_flow_hash (ip0, hc0);
  		}
  	    }
  
  	  dpo0 =
  	    load_balance_get_bucket_i (lb0,
  				       hc0 & (lb0->lb_n_buckets_minus_1));
  
  	  next0 = dpo0->dpoi_next_node;
  	  vnet_buffer (p0)->ip.adj_index[VLIB_TX] = dpo0->dpoi_index;
  
  	  vlib_increment_combined_counter
  	    (cm, cpu_index, lbi0, 1, vlib_buffer_length_in_chain (vm, p0));
  
  	  vlib_validate_buffer_enqueue_x1 (vm, node, next,
  					   to_next, n_left_to_next,
  					   pi0, next0);
  	}
  
        vlib_put_next_frame (vm, node, next, n_left_to_next);
      }
  
    return frame->n_vectors;
  }
  
  VLIB_REGISTER_NODE (ip4_load_balance_node) =
  {
  .function = ip4_load_balance,.name = "ip4-load-balance",.vector_size =
      sizeof (u32),.sibling_of = "ip4-lookup",.format_trace =
      format_ip4_lookup_trace,};
  
  VLIB_NODE_FUNCTION_MULTIARCH (ip4_load_balance_node, ip4_load_balance);
  
  /* get first interface address */
  ip4_address_t *
  ip4_interface_first_address (ip4_main_t * im, u32 sw_if_index,
  			     ip_interface_address_t ** result_ia)
  {
    ip_lookup_main_t *lm = &im->lookup_main;
    ip_interface_address_t *ia = 0;
    ip4_address_t *result = 0;
  
    /* *INDENT-OFF* */
    foreach_ip_interface_address
      (lm, ia, sw_if_index,
       1 /* honor unnumbered */ ,
       ({
         ip4_address_t * a =
           ip_interface_address_get_address (lm, ia);
         result = a;
         break;
       }));
    /* *INDENT-OFF* */
    if (result_ia)
      *result_ia = result ? ia : 0;
    return result;
  }
  
  static void
  ip4_add_interface_routes (u32 sw_if_index,
  			  ip4_main_t * im, u32 fib_index,
  			  ip_interface_address_t * a)
  {
    ip_lookup_main_t *lm = &im->lookup_main;
    ip4_address_t *address = ip_interface_address_get_address (lm, a);
    fib_prefix_t pfx = {
      .fp_len = a->address_length,
      .fp_proto = FIB_PROTOCOL_IP4,
      .fp_addr.ip4 = *address,
    };
  
    a->neighbor_probe_adj_index = ~0;
  
    if (pfx.fp_len < 32)
      {
        fib_node_index_t fei;
  
        fei = fib_table_entry_update_one_path (fib_index, &pfx,
                                               FIB_SOURCE_INTERFACE,
                                               (FIB_ENTRY_FLAG_CONNECTED |
                                                FIB_ENTRY_FLAG_ATTACHED),
                                               FIB_PROTOCOL_IP4,
                                               /* No next-hop address */
                                               NULL,
  					     sw_if_index,
                                               // invalid FIB index
                                               ~0,
  					     1,
                                               // no out-label stack
                                               NULL,
  					     FIB_ROUTE_PATH_FLAG_NONE);
        a->neighbor_probe_adj_index = fib_entry_get_adj (fei);
      }
  
    pfx.fp_len = 32;
  
    if (sw_if_index < vec_len (lm->classify_table_index_by_sw_if_index))
      {
        u32 classify_table_index =
  	lm->classify_table_index_by_sw_if_index[sw_if_index];
        if (classify_table_index != (u32) ~ 0)
  	{
  	  dpo_id_t dpo = DPO_INVALID;
  
  	  dpo_set (&dpo,
  		   DPO_CLASSIFY,
  		   DPO_PROTO_IP4,
  		   classify_dpo_create (DPO_PROTO_IP4, classify_table_index));
  
  	  fib_table_entry_special_dpo_add (fib_index,
  					   &pfx,
  					   FIB_SOURCE_CLASSIFY,
  					   FIB_ENTRY_FLAG_NONE, &dpo);
  	  dpo_reset (&dpo);
  	}
      }
  
    fib_table_entry_update_one_path (fib_index, &pfx,
                                     FIB_SOURCE_INTERFACE,
                                     (FIB_ENTRY_FLAG_CONNECTED |
                                      FIB_ENTRY_FLAG_LOCAL),
                                     FIB_PROTOCOL_IP4,
                                     &pfx.fp_addr,
                                     sw_if_index,
                                     // invalid FIB index
                                     ~0,
  				   1, NULL,
  				   FIB_ROUTE_PATH_FLAG_NONE);
  }
  
  static void
  ip4_del_interface_routes (ip4_main_t * im,
  			  u32 fib_index,
  			  ip4_address_t * address, u32 address_length)
  {
    fib_prefix_t pfx = {
      .fp_len = address_length,
      .fp_proto = FIB_PROTOCOL_IP4,
      .fp_addr.ip4 = *address,
    };
  
    if (pfx.fp_len < 32)
      {
        fib_table_entry_delete (fib_index, &pfx, FIB_SOURCE_INTERFACE);
      }
  
    pfx.fp_len = 32;
    fib_table_entry_delete (fib_index, &pfx, FIB_SOURCE_INTERFACE);
  }
  
  void
  ip4_sw_interface_enable_disable (u32 sw_if_index, u32 is_enable)
  {
    ip4_main_t *im = &ip4_main;
  
    vec_validate_init_empty (im->ip_enabled_by_sw_if_index, sw_if_index, 0);
  
    /*
     * enable/disable only on the 1<->0 transition
     */
    if (is_enable)
      {
        if (1 != ++im->ip_enabled_by_sw_if_index[sw_if_index])
  	return;
      }
    else
      {
        ASSERT (im->ip_enabled_by_sw_if_index[sw_if_index] > 0);
        if (0 != --im->ip_enabled_by_sw_if_index[sw_if_index])
  	return;
      }
    vnet_feature_enable_disable ("ip4-unicast", "ip4-drop", sw_if_index,
  			       !is_enable, 0, 0);
  
  
    vnet_feature_enable_disable ("ip4-multicast",
  			       "ip4-mfib-forward-lookup",
  			       sw_if_index, is_enable, 0, 0);
  }
  
  static clib_error_t *
  ip4_add_del_interface_address_internal (vlib_main_t * vm,
  					u32 sw_if_index,
  					ip4_address_t * address,
  					u32 address_length, u32 is_del)
  {
    vnet_main_t *vnm = vnet_get_main ();
    ip4_main_t *im = &ip4_main;
    ip_lookup_main_t *lm = &im->lookup_main;
    clib_error_t *error = 0;
    u32 if_address_index, elts_before;
    ip4_address_fib_t ip4_af, *addr_fib = 0;
  
    vec_validate (im->fib_index_by_sw_if_index, sw_if_index);
    ip4_addr_fib_init (&ip4_af, address,
  		     vec_elt (im->fib_index_by_sw_if_index, sw_if_index));
    vec_add1 (addr_fib, ip4_af);
  
    /* FIXME-LATER
     * there is no support for adj-fib handling in the presence of overlapping
     * subnets on interfaces. Easy fix - disallow overlapping subnets, like
     * most routers do.
     */
    /* *INDENT-OFF* */
    if (!is_del)
      {
        /* When adding an address check that it does not conflict
           with an existing address. */
        ip_interface_address_t *ia;
        foreach_ip_interface_address
          (&im->lookup_main, ia, sw_if_index,
           0 /* honor unnumbered */ ,
           ({
             ip4_address_t * x =
               ip_interface_address_get_address
               (&im->lookup_main, ia);
             if (ip4_destination_matches_route
                 (im, address, x, ia->address_length) ||
                 ip4_destination_matches_route (im,
                                                x,
                                                address,
                                                address_length))
               return
                 clib_error_create
                 ("failed to add %U which conflicts with %U for interface %U",
                  format_ip4_address_and_length, address,
                  address_length,
                  format_ip4_address_and_length, x,
                  ia->address_length,
                  format_vnet_sw_if_index_name, vnm,
                  sw_if_index);
           }));
      }
    /* *INDENT-ON* */
  
    elts_before = pool_elts (lm->if_address_pool);
  
    error = ip_interface_address_add_del
      (lm, sw_if_index, addr_fib, address_length, is_del, &if_address_index);
    if (error)
      goto done;
  
    ip4_sw_interface_enable_disable (sw_if_index, !is_del);
  
    if (is_del)
      ip4_del_interface_routes (im, ip4_af.fib_index, address, address_length);
    else
      ip4_add_interface_routes (sw_if_index,
  			      im, ip4_af.fib_index,
  			      pool_elt_at_index
  			      (lm->if_address_pool, if_address_index));
  
    /* If pool did not grow/shrink: add duplicate address. */
    if (elts_before != pool_elts (lm->if_address_pool))
      {
        ip4_add_del_interface_address_callback_t *cb;
        vec_foreach (cb, im->add_del_interface_address_callbacks)
  	cb->function (im, cb->function_opaque, sw_if_index,
  		      address, address_length, if_address_index, is_del);
      }
  
  done:
    vec_free (addr_fib);
    return error;
  }
  
  clib_error_t *
  ip4_add_del_interface_address (vlib_main_t * vm,
  			       u32 sw_if_index,
  			       ip4_address_t * address,
  			       u32 address_length, u32 is_del)
  {
    return ip4_add_del_interface_address_internal
      (vm, sw_if_index, address, address_length, is_del);
  }
  
  /* Built-in ip4 unicast rx feature path definition */
  /* *INDENT-OFF* */
  VNET_FEATURE_ARC_INIT (ip4_unicast, static) =
  {
    .arc_name = "ip4-unicast",
    .start_nodes = VNET_FEATURES ("ip4-input", "ip4-input-no-checksum"),
    .end_node = "ip4-lookup",
    .arc_index_ptr = &ip4_main.lookup_main.ucast_feature_arc_index,
  };
  
  VNET_FEATURE_INIT (ip4_flow_classify, static) =
  {
    .arc_name = "ip4-unicast",
    .node_name = "ip4-flow-classify",
    .runs_before = VNET_FEATURES ("ip4-inacl"),
  };
  
  VNET_FEATURE_INIT (ip4_inacl, static) =
  {
    .arc_name = "ip4-unicast",
    .node_name = "ip4-inacl",
    .runs_before = VNET_FEATURES ("ip4-source-check-via-rx"),
  };
  
  VNET_FEATURE_INIT (ip4_source_check_1, static) =
  {
    .arc_name = "ip4-unicast",
    .node_name = "ip4-source-check-via-rx",
    .runs_before = VNET_FEATURES ("ip4-source-check-via-any"),
  };
  
  VNET_FEATURE_INIT (ip4_source_check_2, static) =
  {
    .arc_name = "ip4-unicast",
    .node_name = "ip4-source-check-via-any",
    .runs_before = VNET_FEATURES ("ip4-policer-classify"),
  };
  
  VNET_FEATURE_INIT (ip4_source_and_port_range_check_rx, static) =
  {
    .arc_name = "ip4-unicast",
    .node_name = "ip4-source-and-port-range-check-rx",
    .runs_before = VNET_FEATURES ("ip4-policer-classify"),
  };
  
  VNET_FEATURE_INIT (ip4_policer_classify, static) =
  {
    .arc_name = "ip4-unicast",
    .node_name = "ip4-policer-classify",
    .runs_before = VNET_FEATURES ("ipsec-input-ip4"),
  };
  
  VNET_FEATURE_INIT (ip4_ipsec, static) =
  {
    .arc_name = "ip4-unicast",
    .node_name = "ipsec-input-ip4",
    .runs_before = VNET_FEATURES ("vpath-input-ip4"),
  };
  
  VNET_FEATURE_INIT (ip4_vpath, static) =
  {
    .arc_name = "ip4-unicast",
    .node_name = "vpath-input-ip4",
    .runs_before = VNET_FEATURES ("ip4-vxlan-bypass"),
  };
  
  VNET_FEATURE_INIT (ip4_vxlan_bypass, static) =
  {
    .arc_name = "ip4-unicast",
    .node_name = "ip4-vxlan-bypass",
    .runs_before = VNET_FEATURES ("ip4-lookup"),
  };
  
  VNET_FEATURE_INIT (ip4_lookup, static) =
  {
    .arc_name = "ip4-unicast",
    .node_name = "ip4-lookup",
    .runs_before = VNET_FEATURES ("ip4-drop"),
  };
  
  VNET_FEATURE_INIT (ip4_drop, static) =
  {
    .arc_name = "ip4-unicast",
    .node_name = "ip4-drop",
    .runs_before = 0,	/* not before any other features */
  };
  
  
  /* Built-in ip4 multicast rx feature path definition */
  VNET_FEATURE_ARC_INIT (ip4_multicast, static) =
  {
    .arc_name = "ip4-multicast",
    .start_nodes = VNET_FEATURES ("ip4-input", "ip4-input-no-checksum"),
    .end_node = "ip4-lookup-multicast",
    .arc_index_ptr = &ip4_main.lookup_main.mcast_feature_arc_index,
  };
  
  VNET_FEATURE_INIT (ip4_vpath_mc, static) =
  {
    .arc_name = "ip4-multicast",
    .node_name = "vpath-input-ip4",
    .runs_before = VNET_FEATURES ("ip4-mfib-forward-lookup"),
  };
  
  VNET_FEATURE_INIT (ip4_lookup_mc, static) =
  {
    .arc_name = "ip4-multicast",
    .node_name = "ip4-mfib-forward-lookup",
    .runs_before = VNET_FEATURES ("ip4-drop"),
  };
  
  VNET_FEATURE_INIT (ip4_mc_drop, static) =
  {
    .arc_name = "ip4-multicast",
    .node_name = "ip4-drop",
    .runs_before = 0,	/* last feature */
  };
  
  /* Source and port-range check ip4 tx feature path definition */
  VNET_FEATURE_ARC_INIT (ip4_output, static) =
  {
    .arc_name = "ip4-output",
    .start_nodes = VNET_FEATURES ("ip4-rewrite", "ip4-midchain"),
    .end_node = "interface-output",
    .arc_index_ptr = &ip4_main.lookup_main.output_feature_arc_index,
  };
  
  VNET_FEATURE_INIT (ip4_source_and_port_range_check_tx, static) =
  {
    .arc_name = "ip4-output",
    .node_name = "ip4-source-and-port-range-check-tx",
    .runs_before = VNET_FEATURES ("ipsec-output-ip4"),
  };
  
  VNET_FEATURE_INIT (ip4_ipsec_output, static) =
  {
    .arc_name = "ip4-output",
    .node_name = "ipsec-output-ip4",
    .runs_before = VNET_FEATURES ("interface-output"),
  };
  
  /* Built-in ip4 tx feature path definition */
  VNET_FEATURE_INIT (ip4_interface_output, static) =
  {
    .arc_name = "ip4-output",
    .node_name = "interface-output",
    .runs_before = 0,	/* not before any other features */
  };
  /* *INDENT-ON* */
  
  static clib_error_t *
  ip4_sw_interface_add_del (vnet_main_t * vnm, u32 sw_if_index, u32 is_add)
  {
    ip4_main_t *im = &ip4_main;
  
    /* Fill in lookup tables with default table (0). */
    vec_validate (im->fib_index_by_sw_if_index, sw_if_index);
    vec_validate (im->mfib_index_by_sw_if_index, sw_if_index);
  
    vnet_feature_enable_disable ("ip4-unicast", "ip4-drop", sw_if_index,
  			       is_add, 0, 0);
  
    vnet_feature_enable_disable ("ip4-multicast", "ip4-drop", sw_if_index,
  			       is_add, 0, 0);
  
    return /* no error */ 0;
  }
  
  VNET_SW_INTERFACE_ADD_DEL_FUNCTION (ip4_sw_interface_add_del);
  
  /* Global IP4 main. */
  ip4_main_t ip4_main;
  
  clib_error_t *
  ip4_lookup_init (vlib_main_t * vm)
  {
    ip4_main_t *im = &ip4_main;
    clib_error_t *error;
    uword i;
  
    if ((error = vlib_call_init_function (vm, vnet_feature_init)))
      return error;
  
    for (i = 0; i < ARRAY_LEN (im->fib_masks); i++)
      {
        u32 m;
  
        if (i < 32)
  	m = pow2_mask (i) << (32 - i);
        else
  	m = ~0;
        im->fib_masks[i] = clib_host_to_net_u32 (m);
      }
  
    ip_lookup_init (&im->lookup_main, /* is_ip6 */ 0);
  
    /* Create FIB with index 0 and table id of 0. */
    fib_table_find_or_create_and_lock (FIB_PROTOCOL_IP4, 0);
    mfib_table_find_or_create_and_lock (FIB_PROTOCOL_IP4, 0);
  
    {
      pg_node_t *pn;
      pn = pg_get_node (ip4_lookup_node.index);
      pn->unformat_edit = unformat_pg_ip4_header;
    }
  
    {
      ethernet_arp_header_t h;
  
      memset (&h, 0, sizeof (h));
  
      /* Set target ethernet address to all zeros. */
      memset (h.ip4_over_ethernet[1].ethernet, 0,
  	    sizeof (h.ip4_over_ethernet[1].ethernet));
  
  #define _16(f,v) h.f = clib_host_to_net_u16 (v);
  #define _8(f,v) h.f = v;
      _16 (l2_type, ETHERNET_ARP_HARDWARE_TYPE_ethernet);
      _16 (l3_type, ETHERNET_TYPE_IP4);
      _8 (n_l2_address_bytes, 6);
      _8 (n_l3_address_bytes, 4);
      _16 (opcode, ETHERNET_ARP_OPCODE_request);
  #undef _16
  #undef _8
  
      vlib_packet_template_init (vm, &im->ip4_arp_request_packet_template,
  			       /* data */ &h,
  			       sizeof (h),
  			       /* alloc chunk size */ 8,
  			       "ip4 arp");
    }
  
    return error;
  }
  
  VLIB_INIT_FUNCTION (ip4_lookup_init);
  
  typedef struct
  {
    /* Adjacency taken. */
    u32 dpo_index;
    u32 flow_hash;
    u32 fib_index;
  
    /* Packet data, possibly *after* rewrite. */
    u8 packet_data[64 - 1 * sizeof (u32)];
  }
  ip4_forward_next_trace_t;
  
  u8 *
  format_ip4_forward_next_trace (u8 * s, va_list * args)
  {
    CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
    CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
    ip4_forward_next_trace_t *t = va_arg (*args, ip4_forward_next_trace_t *);
    uword indent = format_get_indent (s);
    s = format (s, "%U%U",
  	      format_white_space, indent,
  	      format_ip4_header, t->packet_data, sizeof (t->packet_data));
    return s;
  }
  
  static u8 *
  format_ip4_lookup_trace (u8 * s, va_list * args)
  {
    CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
    CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
    ip4_forward_next_trace_t *t = va_arg (*args, ip4_forward_next_trace_t *);
    uword indent = format_get_indent (s);
  
    s = format (s, "fib %d dpo-idx %d flow hash: 0x%08x",
  	      t->fib_index, t->dpo_index, t->flow_hash);
    s = format (s, "\n%U%U",
  	      format_white_space, indent,
  	      format_ip4_header, t->packet_data, sizeof (t->packet_data));
    return s;
  }
  
  static u8 *
  format_ip4_rewrite_trace (u8 * s, va_list * args)
  {
    CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
    CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
    ip4_forward_next_trace_t *t = va_arg (*args, ip4_forward_next_trace_t *);
    vnet_main_t *vnm = vnet_get_main ();
    uword indent = format_get_indent (s);
  
    s = format (s, "tx_sw_if_index %d dpo-idx %d : %U flow hash: 0x%08x",
  	      t->fib_index, t->dpo_index, format_ip_adjacency,
  	      t->dpo_index, FORMAT_IP_ADJACENCY_NONE, t->flow_hash);
    s = format (s, "\n%U%U",
  	      format_white_space, indent,
  	      format_ip_adjacency_packet_data,
  	      vnm, t->dpo_index, t->packet_data, sizeof (t->packet_data));
    return s;
  }
  
  /* Common trace function for all ip4-forward next nodes. */
  void
  ip4_forward_next_trace (vlib_main_t * vm,
  			vlib_node_runtime_t * node,
  			vlib_frame_t * frame, vlib_rx_or_tx_t which_adj_index)
  {
    u32 *from, n_left;
    ip4_main_t *im = &ip4_main;
  
    n_left = frame->n_vectors;
    from = vlib_frame_vector_args (frame);
  
    while (n_left >= 4)
      {
        u32 bi0, bi1;
        vlib_buffer_t *b0, *b1;
        ip4_forward_next_trace_t *t0, *t1;
  
        /* Prefetch next iteration. */
        vlib_prefetch_buffer_with_index (vm, from[2], LOAD);
        vlib_prefetch_buffer_with_index (vm, from[3], LOAD);
  
        bi0 = from[0];
        bi1 = from[1];
  
        b0 = vlib_get_buffer (vm, bi0);
        b1 = vlib_get_buffer (vm, bi1);
  
        if (b0->flags & VLIB_BUFFER_IS_TRACED)
  	{
  	  t0 = vlib_add_trace (vm, node, b0, sizeof (t0[0]));
  	  t0->dpo_index = vnet_buffer (b0)->ip.adj_index[which_adj_index];
  	  t0->flow_hash = vnet_buffer (b0)->ip.flow_hash;
  	  t0->fib_index =
  	    (vnet_buffer (b0)->sw_if_index[VLIB_TX] !=
  	     (u32) ~ 0) ? vnet_buffer (b0)->sw_if_index[VLIB_TX] :
  	    vec_elt (im->fib_index_by_sw_if_index,
  		     vnet_buffer (b0)->sw_if_index[VLIB_RX]);
  
  	  clib_memcpy (t0->packet_data,
  		       vlib_buffer_get_current (b0),
  		       sizeof (t0->packet_data));
  	}
        if (b1->flags & VLIB_BUFFER_IS_TRACED)
  	{
  	  t1 = vlib_add_trace (vm, node, b1, sizeof (t1[0]));
  	  t1->dpo_index = vnet_buffer (b1)->ip.adj_index[which_adj_index];
  	  t1->flow_hash = vnet_buffer (b1)->ip.flow_hash;
  	  t1->fib_index =
  	    (vnet_buffer (b1)->sw_if_index[VLIB_TX] !=
  	     (u32) ~ 0) ? vnet_buffer (b1)->sw_if_index[VLIB_TX] :
  	    vec_elt (im->fib_index_by_sw_if_index,
  		     vnet_buffer (b1)->sw_if_index[VLIB_RX]);
  	  clib_memcpy (t1->packet_data, vlib_buffer_get_current (b1),
  		       sizeof (t1->packet_data));
  	}
        from += 2;
        n_left -= 2;
      }
  
    while (n_left >= 1)
      {
        u32 bi0;
        vlib_buffer_t *b0;
        ip4_forward_next_trace_t *t0;
  
        bi0 = from[0];
  
        b0 = vlib_get_buffer (vm, bi0);
  
        if (b0->flags & VLIB_BUFFER_IS_TRACED)
  	{
  	  t0 = vlib_add_trace (vm, node, b0, sizeof (t0[0]));
  	  t0->dpo_index = vnet_buffer (b0)->ip.adj_index[which_adj_index];
  	  t0->flow_hash = vnet_buffer (b0)->ip.flow_hash;
  	  t0->fib_index =
  	    (vnet_buffer (b0)->sw_if_index[VLIB_TX] !=
  	     (u32) ~ 0) ? vnet_buffer (b0)->sw_if_index[VLIB_TX] :
  	    vec_elt (im->fib_index_by_sw_if_index,
  		     vnet_buffer (b0)->sw_if_index[VLIB_RX]);
  	  clib_memcpy (t0->packet_data, vlib_buffer_get_current (b0),
  		       sizeof (t0->packet_data));
  	}
        from += 1;
        n_left -= 1;
      }
  }
  
  static uword
  ip4_drop_or_punt (vlib_main_t * vm,
  		  vlib_node_runtime_t * node,
  		  vlib_frame_t * frame, ip4_error_t error_code)
  {
    u32 *buffers = vlib_frame_vector_args (frame);
    uword n_packets = frame->n_vectors;
  
    vlib_error_drop_buffers (vm, node, buffers,
  			   /* stride */ 1,
  			   n_packets,
  			   /* next */ 0,
  			   ip4_input_node.index, error_code);
  
    if (node->flags & VLIB_NODE_FLAG_TRACE)
      ip4_forward_next_trace (vm, node, frame, VLIB_TX);
  
    return n_packets;
  }
  
  static uword
  ip4_drop (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
  {
    return ip4_drop_or_punt (vm, node, frame, IP4_ERROR_ADJACENCY_DROP);
  }
  
  static uword
  ip4_punt (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
  {
    return ip4_drop_or_punt (vm, node, frame, IP4_ERROR_ADJACENCY_PUNT);
  }
  
  /* *INDENT-OFF* */
  VLIB_REGISTER_NODE (ip4_drop_node, static) =
  {
    .function = ip4_drop,.
    name = "ip4-drop",
    .vector_size = sizeof (u32),
    .format_trace = format_ip4_forward_next_trace,
    .n_next_nodes = 1,
    .next_nodes = {
      [0] = "error-drop",
    },
  };
  
  VLIB_NODE_FUNCTION_MULTIARCH (ip4_drop_node, ip4_drop);
  
  VLIB_REGISTER_NODE (ip4_punt_node, static) =
  {
    .function = ip4_punt,
    .name = "ip4-punt",
    .vector_size = sizeof (u32),
    .format_trace = format_ip4_forward_next_trace,
    .n_next_nodes = 1,
    .next_nodes = {
      [0] = "error-punt",
    },
  };
  
  VLIB_NODE_FUNCTION_MULTIARCH (ip4_punt_node, ip4_punt);
  /* *INDENT-ON */
  
  /* Compute TCP/UDP/ICMP4 checksum in software. */
  u16
  ip4_tcp_udp_compute_checksum (vlib_main_t * vm, vlib_buffer_t * p0,
  			      ip4_header_t * ip0)
  {
    ip_csum_t sum0;
    u32 ip_header_length, payload_length_host_byte_order;
    u32 n_this_buffer, n_bytes_left;
    u16 sum16;
    void *data_this_buffer;
  
    /* Initialize checksum with ip header. */
    ip_header_length = ip4_header_bytes (ip0);
    payload_length_host_byte_order =
      clib_net_to_host_u16 (ip0->length) - ip_header_length;
    sum0 =
      clib_host_to_net_u32 (payload_length_host_byte_order +
  			  (ip0->protocol << 16));
  
    if (BITS (uword) == 32)
      {
        sum0 =
  	ip_csum_with_carry (sum0,
  			    clib_mem_unaligned (&ip0->src_address, u32));
        sum0 =
  	ip_csum_with_carry (sum0,
  			    clib_mem_unaligned (&ip0->dst_address, u32));
      }
    else
      sum0 =
        ip_csum_with_carry (sum0, clib_mem_unaligned (&ip0->src_address, u64));
  
    n_bytes_left = n_this_buffer = payload_length_host_byte_order;
    data_this_buffer = (void *) ip0 + ip_header_length;
    if (n_this_buffer + ip_header_length > p0->current_length)
      n_this_buffer =
        p0->current_length >
        ip_header_length ? p0->current_length - ip_header_length : 0;
    while (1)
      {
        sum0 = ip_incremental_checksum (sum0, data_this_buffer, n_this_buffer);
        n_bytes_left -= n_this_buffer;
        if (n_bytes_left == 0)
  	break;
  
        ASSERT (p0->flags & VLIB_BUFFER_NEXT_PRESENT);
        p0 = vlib_get_buffer (vm, p0->next_buffer);
        data_this_buffer = vlib_buffer_get_current (p0);
        n_this_buffer = p0->current_length;
      }
  
    sum16 = ~ip_csum_fold (sum0);
  
    return sum16;
  }
  
  u32
  ip4_tcp_udp_validate_checksum (vlib_main_t * vm, vlib_buffer_t * p0)
  {
    ip4_header_t *ip0 = vlib_buffer_get_current (p0);
    udp_header_t *udp0;
    u16 sum16;
  
    ASSERT (ip0->protocol == IP_PROTOCOL_TCP
  	  || ip0->protocol == IP_PROTOCOL_UDP);
  
    udp0 = (void *) (ip0 + 1);
    if (ip0->protocol == IP_PROTOCOL_UDP && udp0->checksum == 0)
      {
        p0->flags |= (IP_BUFFER_L4_CHECKSUM_COMPUTED
  		    | IP_BUFFER_L4_CHECKSUM_CORRECT);
        return p0->flags;
      }
  
    sum16 = ip4_tcp_udp_compute_checksum (vm, p0, ip0);
  
    p0->flags |= (IP_BUFFER_L4_CHECKSUM_COMPUTED
  		| ((sum16 == 0) << LOG2_IP_BUFFER_L4_CHECKSUM_CORRECT));
  
    return p0->flags;
  }
  
  /* *INDENT-OFF* */
  VNET_FEATURE_ARC_INIT (ip4_local) =
  {
    .arc_name  = "ip4-local",
    .start_nodes = VNET_FEATURES ("ip4-local"),
  };
  /* *INDENT-ON* */
  
  static inline uword
  ip4_local_inline (vlib_main_t * vm,
  		  vlib_node_runtime_t * node,
  		  vlib_frame_t * frame, int head_of_feature_arc)
  {
    ip4_main_t *im = &ip4_main;
    ip_lookup_main_t *lm = &im->lookup_main;
    ip_local_next_t next_index;
    u32 *from, *to_next, n_left_from, n_left_to_next;
    vlib_node_runtime_t *error_node =
      vlib_node_get_runtime (vm, ip4_input_node.index);
    u8 arc_index = vnet_feat_arc_ip4_local.feature_arc_index;
  
    from = vlib_frame_vector_args (frame);
    n_left_from = frame->n_vectors;
    next_index = node->cached_next_index;
  
    if (node->flags & VLIB_NODE_FLAG_TRACE)
      ip4_forward_next_trace (vm, node, frame, VLIB_TX);
  
    while (n_left_from > 0)
      {
        vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
  
        while (n_left_from >= 4 && n_left_to_next >= 2)
  	{
  	  vlib_buffer_t *p0, *p1;
  	  ip4_header_t *ip0, *ip1;
  	  udp_header_t *udp0, *udp1;
  	  ip4_fib_mtrie_t *mtrie0, *mtrie1;
  	  ip4_fib_mtrie_leaf_t leaf0, leaf1;
  	  const dpo_id_t *dpo0, *dpo1;
  	  const load_balance_t *lb0, *lb1;
  	  u32 pi0, ip_len0, udp_len0, flags0, next0, fib_index0, lbi0;
  	  u32 pi1, ip_len1, udp_len1, flags1, next1, fib_index1, lbi1;
  	  i32 len_diff0, len_diff1;
  	  u8 error0, is_udp0, is_tcp_udp0, good_tcp_udp0, proto0;
  	  u8 error1, is_udp1, is_tcp_udp1, good_tcp_udp1, proto1;
  	  u32 sw_if_index0, sw_if_index1;
  
  	  pi0 = to_next[0] = from[0];
  	  pi1 = to_next[1] = from[1];
  	  from += 2;
  	  n_left_from -= 2;
  	  to_next += 2;
  	  n_left_to_next -= 2;
  
  	  next0 = next1 = IP_LOCAL_NEXT_DROP;
  
  	  p0 = vlib_get_buffer (vm, pi0);
  	  p1 = vlib_get_buffer (vm, pi1);
  
  	  ip0 = vlib_buffer_get_current (p0);
  	  ip1 = vlib_buffer_get_current (p1);
  
  	  vnet_buffer (p0)->ip.start_of_ip_header = p0->current_data;
  	  vnet_buffer (p1)->ip.start_of_ip_header = p1->current_data;
  
  	  sw_if_index0 = vnet_buffer (p0)->sw_if_index[VLIB_RX];
  	  sw_if_index1 = vnet_buffer (p1)->sw_if_index[VLIB_RX];
  
  	  fib_index0 = vec_elt (im->fib_index_by_sw_if_index, sw_if_index0);
  	  fib_index1 = vec_elt (im->fib_index_by_sw_if_index, sw_if_index1);
  
  	  fib_index0 = vec_elt (im->fib_index_by_sw_if_index, sw_if_index0);
  	  fib_index0 =
  	    (vnet_buffer (p0)->sw_if_index[VLIB_TX] ==
  	     (u32) ~ 0) ? fib_index0 : vnet_buffer (p0)->sw_if_index[VLIB_TX];
  
  	  fib_index1 = vec_elt (im->fib_index_by_sw_if_index, sw_if_index1);
  	  fib_index1 =
  	    (vnet_buffer (p1)->sw_if_index[VLIB_TX] ==
  	     (u32) ~ 0) ? fib_index1 : vnet_buffer (p1)->sw_if_index[VLIB_TX];
  
  	  mtrie0 = &ip4_fib_get (fib_index0)->mtrie;
  	  mtrie1 = &ip4_fib_get (fib_index1)->mtrie;
  
  	  leaf0 = leaf1 = IP4_FIB_MTRIE_LEAF_ROOT;
  
  	  leaf0 =
  	    ip4_fib_mtrie_lookup_step (mtrie0, leaf0, &ip0->src_address, 0);
  	  leaf1 =
  	    ip4_fib_mtrie_lookup_step (mtrie1, leaf1, &ip1->src_address, 0);
  
  	  /* Treat IP frag packets as "experimental" protocol for now
  	     until support of IP frag reassembly is implemented */
  	  proto0 = ip4_is_fragment (ip0) ? 0xfe : ip0->protocol;
  	  proto1 = ip4_is_fragment (ip1) ? 0xfe : ip1->protocol;
  
  	  if (head_of_feature_arc == 0)
  	    {
  	      error0 = error1 = IP4_ERROR_UNKNOWN_PROTOCOL;
  	      goto skip_checks;
  	    }
  
  	  is_udp0 = proto0 == IP_PROTOCOL_UDP;
  	  is_udp1 = proto1 == IP_PROTOCOL_UDP;
  	  is_tcp_udp0 = is_udp0 || proto0 == IP_PROTOCOL_TCP;
  	  is_tcp_udp1 = is_udp1 || proto1 == IP_PROTOCOL_TCP;
  
  	  flags0 = p0->flags;
  	  flags1 = p1->flags;
  
  	  good_tcp_udp0 = (flags0 & IP_BUFFER_L4_CHECKSUM_CORRECT) != 0;
  	  good_tcp_udp1 = (flags1 & IP_BUFFER_L4_CHECKSUM_CORRECT) != 0;
  
  	  udp0 = ip4_next_header (ip0);
  	  udp1 = ip4_next_header (ip1);
  
  	  /* Don't verify UDP checksum for packets with explicit zero checksum. */
  	  good_tcp_udp0 |= is_udp0 && udp0->checksum == 0;
  	  good_tcp_udp1 |= is_udp1 && udp1->checksum == 0;
  
  	  leaf0 =
  	    ip4_fib_mtrie_lookup_step (mtrie0, leaf0, &ip0->src_address, 1);
  	  leaf1 =
  	    ip4_fib_mtrie_lookup_step (mtrie1, leaf1, &ip1->src_address, 1);
  
  	  /* Verify UDP length. */
  	  ip_len0 = clib_net_to_host_u16 (ip0->length);
  	  ip_len1 = clib_net_to_host_u16 (ip1->length);
  	  udp_len0 = clib_net_to_host_u16 (udp0->length);
  	  udp_len1 = clib_net_to_host_u16 (udp1->length);
  
  	  len_diff0 = ip_len0 - udp_len0;
  	  len_diff1 = ip_len1 - udp_len1;
  
  	  len_diff0 = is_udp0 ? len_diff0 : 0;
  	  len_diff1 = is_udp1 ? len_diff1 : 0;
  
  	  if (PREDICT_FALSE (!(is_tcp_udp0 & is_tcp_udp1
  			       & good_tcp_udp0 & good_tcp_udp1)))
  	    {
  	      if (is_tcp_udp0)
  		{
  		  if (is_tcp_udp0
  		      && !(flags0 & IP_BUFFER_L4_CHECKSUM_COMPUTED))
  		    flags0 = ip4_tcp_udp_validate_checksum (vm, p0);
  		  good_tcp_udp0 =
  		    (flags0 & IP_BUFFER_L4_CHECKSUM_CORRECT) != 0;
  		  good_tcp_udp0 |= is_udp0 && udp0->checksum == 0;
  		}
  	      if (is_tcp_udp1)
  		{
  		  if (is_tcp_udp1
  		      && !(flags1 & IP_BUFFER_L4_CHECKSUM_COMPUTED))
  		    flags1 = ip4_tcp_udp_validate_checksum (vm, p1);
  		  good_tcp_udp1 =
  		    (flags1 & IP_BUFFER_L4_CHECKSUM_CORRECT) != 0;
  		  good_tcp_udp1 |= is_udp1 && udp1->checksum == 0;
  		}
  	    }
  
  	  good_tcp_udp0 &= len_diff0 >= 0;
  	  good_tcp_udp1 &= len_diff1 >= 0;
  
  	  leaf0 =
  	    ip4_fib_mtrie_lookup_step (mtrie0, leaf0, &ip0->src_address, 2);
  	  leaf1 =
  	    ip4_fib_mtrie_lookup_step (mtrie1, leaf1, &ip1->src_address, 2);
  
  	  error0 = error1 = IP4_ERROR_UNKNOWN_PROTOCOL;
  
  	  error0 = len_diff0 < 0 ? IP4_ERROR_UDP_LENGTH : error0;
  	  error1 = len_diff1 < 0 ? IP4_ERROR_UDP_LENGTH : error1;
  
  	  ASSERT (IP4_ERROR_TCP_CHECKSUM + 1 == IP4_ERROR_UDP_CHECKSUM);
  	  error0 = (is_tcp_udp0 && !good_tcp_udp0
  		    ? IP4_ERROR_TCP_CHECKSUM + is_udp0 : error0);
  	  error1 = (is_tcp_udp1 && !good_tcp_udp1
  		    ? IP4_ERROR_TCP_CHECKSUM + is_udp1 : error1);
  
  	  leaf0 =
  	    ip4_fib_mtrie_lookup_step (mtrie0, leaf0, &ip0->src_address, 3);
  	  leaf1 =
  	    ip4_fib_mtrie_lookup_step (mtrie1, leaf1, &ip1->src_address, 3);
  	  leaf0 =
  	    (leaf0 ==
  	     IP4_FIB_MTRIE_LEAF_EMPTY ? mtrie0->default_leaf : leaf0);
  	  leaf1 =
  	    (leaf1 ==
  	     IP4_FIB_MTRIE_LEAF_EMPTY ? mtrie1->default_leaf : leaf1);
  
  	  vnet_buffer (p0)->ip.adj_index[VLIB_RX] = lbi0 =
  	    ip4_fib_mtrie_leaf_get_adj_index (leaf0);
  	  vnet_buffer (p0)->ip.adj_index[VLIB_TX] = lbi0;
  
  	  vnet_buffer (p1)->ip.adj_index[VLIB_RX] = lbi1 =
  	    ip4_fib_mtrie_leaf_get_adj_index (leaf1);
  	  vnet_buffer (p1)->ip.adj_index[VLIB_TX] = lbi1;
  
  	  lb0 = load_balance_get (lbi0);
  	  lb1 = load_balance_get (lbi1);
  	  dpo0 = load_balance_get_bucket_i (lb0, 0);
  	  dpo1 = load_balance_get_bucket_i (lb1, 0);
  
  	  /*
  	   * Must have a route to source otherwise we drop the packet.
  	   * ip4 broadcasts are accepted, e.g. to make dhcp client work
  	   *
  	   * The checks are:
  	   *  - the source is a recieve => it's from us => bogus, do this
  	   *    first since it sets a different error code.
  	   *  - uRPF check for any route to source - accept if passes.
  	   *  - allow packets destined to the broadcast address from unknown sources
  	   */
  	  error0 = ((error0 == IP4_ERROR_UNKNOWN_PROTOCOL &&
  		     dpo0->dpoi_type == DPO_RECEIVE) ?
  		    IP4_ERROR_SPOOFED_LOCAL_PACKETS : error0);
  	  error0 = ((error0 == IP4_ERROR_UNKNOWN_PROTOCOL &&
  		     !fib_urpf_check_size (lb0->lb_urpf) &&
  		     ip0->dst_address.as_u32 != 0xFFFFFFFF)
  		    ? IP4_ERROR_SRC_LOOKUP_MISS : error0);
  	  error1 = ((error1 == IP4_ERROR_UNKNOWN_PROTOCOL &&
  		     dpo1->dpoi_type == DPO_RECEIVE) ?
  		    IP4_ERROR_SPOOFED_LOCAL_PACKETS : error1);
  	  error1 = ((error1 == IP4_ERROR_UNKNOWN_PROTOCOL &&
  		     !fib_urpf_check_size (lb1->lb_urpf) &&
  		     ip1->dst_address.as_u32 != 0xFFFFFFFF)
  		    ? IP4_ERROR_SRC_LOOKUP_MISS : error1);
  
  	  next0 = lm->local_next_by_ip_protocol[proto0];
  	  next1 = lm->local_next_by_ip_protocol[proto1];
  
  	skip_checks:
  	  next0 =
  	    error0 != IP4_ERROR_UNKNOWN_PROTOCOL ? IP_LOCAL_NEXT_DROP : next0;
  	  next1 =
  	    error1 != IP4_ERROR_UNKNOWN_PROTOCOL ? IP_LOCAL_NEXT_DROP : next1;
  
  	  p0->error = error0 ? error_node->errors[error0] : 0;
  	  p1->error = error1 ? error_node->errors[error1] : 0;
  
  	  if (head_of_feature_arc)
  	    {
  	      if (PREDICT_TRUE (error0 == (u8) IP4_ERROR_UNKNOWN_PROTOCOL))
  		vnet_feature_arc_start (arc_index, sw_if_index0, &next0, p0);
  	      if (PREDICT_TRUE (error1 == (u8) IP4_ERROR_UNKNOWN_PROTOCOL))
  		vnet_feature_arc_start (arc_index, sw_if_index1, &next1, p1);
  	    }
  
  	  vlib_validate_buffer_enqueue_x2 (vm, node, next_index, to_next,
  					   n_left_to_next, pi0, pi1,
  					   next0, next1);
  	}
  
        while (n_left_from > 0 && n_left_to_next > 0)
  	{
  	  vlib_buffer_t *p0;
  	  ip4_header_t *ip0;
  	  udp_header_t *udp0;
  	  ip4_fib_mtrie_t *mtrie0;
  	  ip4_fib_mtrie_leaf_t leaf0;
  	  u32 pi0, next0, ip_len0, udp_len0, flags0, fib_index0, lbi0;
  	  i32 len_diff0;
  	  u8 error0, is_udp0, is_tcp_udp0, good_tcp_udp0, proto0;
  	  load_balance_t *lb0;
  	  const dpo_id_t *dpo0;
  	  u32 sw_if_index0;
  
  	  pi0 = to_next[0] = from[0];
  	  from += 1;
  	  n_left_from -= 1;
  	  to_next += 1;
  	  n_left_to_next -= 1;
  
  	  next0 = IP_LOCAL_NEXT_DROP;
  
  	  p0 = vlib_get_buffer (vm, pi0);
  
  	  ip0 = vlib_buffer_get_current (p0);
  
  	  vnet_buffer (p0)->ip.start_of_ip_header = p0->current_data;
  
  	  sw_if_index0 = vnet_buffer (p0)->sw_if_index[VLIB_RX];
  
  	  fib_index0 = vec_elt (im->fib_index_by_sw_if_index, sw_if_index0);
  
  	  fib_index0 =
  	    (vnet_buffer (p0)->sw_if_index[VLIB_TX] ==
  	     (u32) ~ 0) ? fib_index0 : vnet_buffer (p0)->sw_if_index[VLIB_TX];
  
  	  mtrie0 = &ip4_fib_get (fib_index0)->mtrie;
  
  	  leaf0 = IP4_FIB_MTRIE_LEAF_ROOT;
  
  	  leaf0 =
  	    ip4_fib_mtrie_lookup_step (mtrie0, leaf0, &ip0->src_address, 0);
  
  	  /* Treat IP frag packets as "experimental" protocol for now
  	     until support of IP frag reassembly is implemented */
  	  proto0 = ip4_is_fragment (ip0) ? 0xfe : ip0->protocol;
  
  	  if (head_of_feature_arc == 0)
  	    {
  	      error0 = IP4_ERROR_UNKNOWN_PROTOCOL;
  	      goto skip_check;
  	    }
  
  	  is_udp0 = proto0 == IP_PROTOCOL_UDP;
  	  is_tcp_udp0 = is_udp0 || proto0 == IP_PROTOCOL_TCP;
  
  	  flags0 = p0->flags;
  
  	  good_tcp_udp0 = (flags0 & IP_BUFFER_L4_CHECKSUM_CORRECT) != 0;
  
  	  udp0 = ip4_next_header (ip0);
  
  	  /* Don't verify UDP checksum for packets with explicit zero checksum. */
  	  good_tcp_udp0 |= is_udp0 && udp0->checksum == 0;
  
  	  leaf0 =
  	    ip4_fib_mtrie_lookup_step (mtrie0, leaf0, &ip0->src_address, 1);
  
  	  /* Verify UDP length. */
  	  ip_len0 = clib_net_to_host_u16 (ip0->length);
  	  udp_len0 = clib_net_to_host_u16 (udp0->length);
  
  	  len_diff0 = ip_len0 - udp_len0;
  
  	  len_diff0 = is_udp0 ? len_diff0 : 0;
  
  	  if (PREDICT_FALSE (!(is_tcp_udp0 & good_tcp_udp0)))
  	    {
  	      if (is_tcp_udp0)
  		{
  		  if (is_tcp_udp0
  		      && !(flags0 & IP_BUFFER_L4_CHECKSUM_COMPUTED))
  		    flags0 = ip4_tcp_udp_validate_checksum (vm, p0);
  		  good_tcp_udp0 =
  		    (flags0 & IP_BUFFER_L4_CHECKSUM_CORRECT) != 0;
  		  good_tcp_udp0 |= is_udp0 && udp0->checksum == 0;
  		}
  	    }
  
  	  good_tcp_udp0 &= len_diff0 >= 0;
  
  	  leaf0 =
  	    ip4_fib_mtrie_lookup_step (mtrie0, leaf0, &ip0->src_address, 2);
  
  	  error0 = IP4_ERROR_UNKNOWN_PROTOCOL;
  
  	  error0 = len_diff0 < 0 ? IP4_ERROR_UDP_LENGTH : error0;
  
  	  ASSERT (IP4_ERROR_TCP_CHECKSUM + 1 == IP4_ERROR_UDP_CHECKSUM);
  	  error0 = (is_tcp_udp0 && !good_tcp_udp0
  		    ? IP4_ERROR_TCP_CHECKSUM + is_udp0 : error0);
  
  	  leaf0 =
  	    ip4_fib_mtrie_lookup_step (mtrie0, leaf0, &ip0->src_address, 3);
  	  leaf0 =
  	    (leaf0 ==
  	     IP4_FIB_MTRIE_LEAF_EMPTY ? mtrie0->default_leaf : leaf0);
  
  	  lbi0 = ip4_fib_mtrie_leaf_get_adj_index (leaf0);
  	  vnet_buffer (p0)->ip.adj_index[VLIB_TX] = lbi0;
  
  	  lb0 = load_balance_get (lbi0);
  	  dpo0 = load_balance_get_bucket_i (lb0, 0);
  
  	  vnet_buffer (p0)->ip.adj_index[VLIB_TX] =
  	    vnet_buffer (p0)->ip.adj_index[VLIB_RX] = lbi0;
  
  	  error0 = ((error0 == IP4_ERROR_UNKNOWN_PROTOCOL &&
  		     dpo0->dpoi_type == DPO_RECEIVE) ?
  		    IP4_ERROR_SPOOFED_LOCAL_PACKETS : error0);
  	  error0 = ((error0 == IP4_ERROR_UNKNOWN_PROTOCOL &&
  		     !fib_urpf_check_size (lb0->lb_urpf) &&
  		     ip0->dst_address.as_u32 != 0xFFFFFFFF)
  		    ? IP4_ERROR_SRC_LOOKUP_MISS : error0);
  
  	skip_check:
  
  	  next0 = lm->local_next_by_ip_protocol[proto0];
  
  	  next0 =
  	    error0 != IP4_ERROR_UNKNOWN_PROTOCOL ? IP_LOCAL_NEXT_DROP : next0;
  
  	  p0->error = error0 ? error_node->errors[error0] : 0;
  
  	  if (head_of_feature_arc)
  	    {
  	      if (PREDICT_TRUE (error0 == (u8) IP4_ERROR_UNKNOWN_PROTOCOL))
  		vnet_feature_arc_start (arc_index, sw_if_index0, &next0, p0);
  	    }
  
  	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
  					   n_left_to_next, pi0, next0);
  
  	}
  
        vlib_put_next_frame (vm, node, next_index, n_left_to_next);
      }
  
    return frame->n_vectors;
  }
  
  static uword
  ip4_local (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
  {
    return ip4_local_inline (vm, node, frame, 1 /* head of feature arc */ );
  }
  
  /* *INDENT-OFF* */
  VLIB_REGISTER_NODE (ip4_local_node) =
  {
    .function = ip4_local,
    .name = "ip4-local",
    .vector_size = sizeof (u32),
    .format_trace = format_ip4_forward_next_trace,
    .n_next_nodes = IP_LOCAL_N_NEXT,
    .next_nodes =
    {
      [IP_LOCAL_NEXT_DROP] = "error-drop",
      [IP_LOCAL_NEXT_PUNT] = "error-punt",
      [IP_LOCAL_NEXT_UDP_LOOKUP] = "ip4-udp-lookup",
      [IP_LOCAL_NEXT_ICMP] = "ip4-icmp-input",},
  };
  /* *INDENT-ON* */
  
  VLIB_NODE_FUNCTION_MULTIARCH (ip4_local_node, ip4_local);
  
  static uword
  ip4_local_end_of_arc (vlib_main_t * vm,
  		      vlib_node_runtime_t * node, vlib_frame_t * frame)
  {
    return ip4_local_inline (vm, node, frame, 0 /* head of feature arc */ );
  }
  
  /* *INDENT-OFF* */
  VLIB_REGISTER_NODE (ip4_local_end_of_arc_node,static) = {
    .function = ip4_local_end_of_arc,
    .name = "ip4-local-end-of-arc",
    .vector_size = sizeof (u32),
  
    .format_trace = format_ip4_forward_next_trace,
    .sibling_of = "ip4-local",
  };
  
  VLIB_NODE_FUNCTION_MULTIARCH (ip4_local_end_of_arc_node, ip4_local_end_of_arc)
  
  VNET_FEATURE_INIT (ip4_local_end_of_arc, static) = {
    .arc_name = "ip4-local",
    .node_name = "ip4-local-end-of-arc",
    .runs_before = 0, /* not before any other features */
  };
  /* *INDENT-ON* */
  
  void
  ip4_register_protocol (u32 protocol, u32 node_index)
  {
    vlib_main_t *vm = vlib_get_main ();
    ip4_main_t *im = &ip4_main;
    ip_lookup_main_t *lm = &im->lookup_main;
  
    ASSERT (protocol < ARRAY_LEN (lm->local_next_by_ip_protocol));
    lm->local_next_by_ip_protocol[protocol] =
      vlib_node_add_next (vm, ip4_local_node.index, node_index);
  }
  
  static clib_error_t *
  show_ip_local_command_fn (vlib_main_t * vm,
  			  unformat_input_t * input, vlib_cli_command_t * cmd)
  {
    ip4_main_t *im = &ip4_main;
    ip_lookup_main_t *lm = &im->lookup_main;
    int i;
  
    vlib_cli_output (vm, "Protocols handled by ip4_local");
    for (i = 0; i < ARRAY_LEN (lm->local_next_by_ip_protocol); i++)
      {
        if (lm->local_next_by_ip_protocol[i] != IP_LOCAL_NEXT_PUNT)
  	vlib_cli_output (vm, "%d", i);
      }
    return 0;
  }
  
  
  
  /*?
   * Display the set of protocols handled by the local IPv4 stack.
   *
   * @cliexpar
   * Example of how to display local protocol table:
   * @cliexstart{show ip local}
   * Protocols handled by ip4_local
   * 1
   * 17
   * 47
   * @cliexend
  ?*/
  /* *INDENT-OFF* */
  VLIB_CLI_COMMAND (show_ip_local, static) =
  {
    .path = "show ip local",
    .function = show_ip_local_command_fn,
    .short_help = "show ip local",
  };
  /* *INDENT-ON* */
  
  always_inline uword
  ip4_arp_inline (vlib_main_t * vm,
  		vlib_node_runtime_t * node,
  		vlib_frame_t * frame, int is_glean)
  {
    vnet_main_t *vnm = vnet_get_main ();
    ip4_main_t *im = &ip4_main;
    ip_lookup_main_t *lm = &im->lookup_main;
    u32 *from, *to_next_drop;
    uword n_left_from, n_left_to_next_drop, next_index;
    static f64 time_last_seed_change = -1e100;
    static u32 hash_seeds[3];
    static uword hash_bitmap[256 / BITS (uword)];
    f64 time_now;
  
    if (node->flags & VLIB_NODE_FLAG_TRACE)
      ip4_forward_next_trace (vm, node, frame, VLIB_TX);
  
    time_now = vlib_time_now (vm);
    if (time_now - time_last_seed_change > 1e-3)
      {
        uword i;
        u32 *r = clib_random_buffer_get_data (&vm->random_buffer,
  					    sizeof (hash_seeds));
        for (i = 0; i < ARRAY_LEN (hash_seeds); i++)
  	hash_seeds[i] = r[i];
  
        /* Mark all hash keys as been no-seen before. */
        for (i = 0; i < ARRAY_LEN (hash_bitmap); i++)
  	hash_bitmap[i] = 0;
  
        time_last_seed_change = time_now;
      }
  
    from = vlib_frame_vector_args (frame);
    n_left_from = frame->n_vectors;
    next_index = node->cached_next_index;
    if (next_index == IP4_ARP_NEXT_DROP)
      next_index = IP4_ARP_N_NEXT;	/* point to first interface */
  
    while (n_left_from > 0)
      {
        vlib_get_next_frame (vm, node, IP4_ARP_NEXT_DROP,
  			   to_next_drop, n_left_to_next_drop);
  
        while (n_left_from > 0 && n_left_to_next_drop > 0)
  	{
  	  u32 pi0, adj_index0, a0, b0, c0, m0, sw_if_index0, drop0;
  	  ip_adjacency_t *adj0;
  	  vlib_buffer_t *p0;
  	  ip4_header_t *ip0;
  	  uword bm0;
  
  	  pi0 = from[0];
  
  	  p0 = vlib_get_buffer (vm, pi0);
  
  	  adj_index0 = vnet_buffer (p0)->ip.adj_index[VLIB_TX];
  	  adj0 = ip_get_adjacency (lm, adj_index0);
  	  ip0 = vlib_buffer_get_current (p0);
  
  	  a0 = hash_seeds[0];
  	  b0 = hash_seeds[1];
  	  c0 = hash_seeds[2];
  
  	  sw_if_index0 = adj0->rewrite_header.sw_if_index;
  	  vnet_buffer (p0)->sw_if_index[VLIB_TX] = sw_if_index0;
  
  	  if (is_glean)
  	    {
  	      /*
  	       * this is the Glean case, so we are ARPing for the
  	       * packet's destination
  	       */
  	      a0 ^= ip0->dst_address.data_u32;
  	    }
  	  else
  	    {
  	      a0 ^= adj0->sub_type.nbr.next_hop.ip4.data_u32;
  	    }
  	  b0 ^= sw_if_index0;
  
  	  hash_v3_finalize32 (a0, b0, c0);
  
  	  c0 &= BITS (hash_bitmap) - 1;
  	  c0 = c0 / BITS (uword);
  	  m0 = (uword) 1 << (c0 % BITS (uword));
  
  	  bm0 = hash_bitmap[c0];
  	  drop0 = (bm0 & m0) != 0;
  
  	  /* Mark it as seen. */
  	  hash_bitmap[c0] = bm0 | m0;
  
  	  from += 1;
  	  n_left_from -= 1;
  	  to_next_drop[0] = pi0;
  	  to_next_drop += 1;
  	  n_left_to_next_drop -= 1;
  
  	  p0->error =
  	    node->errors[drop0 ? IP4_ARP_ERROR_DROP :
  			 IP4_ARP_ERROR_REQUEST_SENT];
  
  	  /*
  	   * the adj has been updated to a rewrite but the node the DPO that got
  	   * us here hasn't - yet. no big deal. we'll drop while we wait.
  	   */
  	  if (IP_LOOKUP_NEXT_REWRITE == adj0->lookup_next_index)
  	    continue;
  
  	  if (drop0)
  	    continue;
  
  	  /*
  	   * Can happen if the control-plane is programming tables
  	   * with traffic flowing; at least that's today's lame excuse.
  	   */
  	  if ((is_glean && adj0->lookup_next_index != IP_LOOKUP_NEXT_GLEAN)
  	      || (!is_glean && adj0->lookup_next_index != IP_LOOKUP_NEXT_ARP))
  	    {
  	      p0->error = node->errors[IP4_ARP_ERROR_NON_ARP_ADJ];
  	    }
  	  else
  	    /* Send ARP request. */
  	    {
  	      u32 bi0 = 0;
  	      vlib_buffer_t *b0;
  	      ethernet_arp_header_t *h0;
  	      vnet_hw_interface_t *hw_if0;
  
  	      h0 =
  		vlib_packet_template_get_packet (vm,
  						 &im->ip4_arp_request_packet_template,
  						 &bi0);
  
  	      /* Add rewrite/encap string for ARP packet. */
  	      vnet_rewrite_one_header (adj0[0], h0,
  				       sizeof (ethernet_header_t));
  
  	      hw_if0 = vnet_get_sup_hw_interface (vnm, sw_if_index0);
  
  	      /* Src ethernet address in ARP header. */
  	      clib_memcpy (h0->ip4_over_ethernet[0].ethernet,
  			   hw_if0->hw_address,
  			   sizeof (h0->ip4_over_ethernet[0].ethernet));
  
  	      if (is_glean)
  		{
  		  /* The interface's source address is stashed in the Glean Adj */
  		  h0->ip4_over_ethernet[0].ip4 =
  		    adj0->sub_type.glean.receive_addr.ip4;
  
  		  /* Copy in destination address we are requesting. This is the
  		   * glean case, so it's the packet's destination.*/
  		  h0->ip4_over_ethernet[1].ip4.data_u32 =
  		    ip0->dst_address.data_u32;
  		}
  	      else
  		{
  		  /* Src IP address in ARP header. */
  		  if (ip4_src_address_for_packet (lm, sw_if_index0,
  						  &h0->
  						  ip4_over_ethernet[0].ip4))
  		    {
  		      /* No source address available */
  		      p0->error =
  			node->errors[IP4_ARP_ERROR_NO_SOURCE_ADDRESS];
  		      vlib_buffer_free (vm, &bi0, 1);
  		      continue;
  		    }
  
  		  /* Copy in destination address we are requesting from the
  		     incomplete adj */
  		  h0->ip4_over_ethernet[1].ip4.data_u32 =
  		    adj0->sub_type.nbr.next_hop.ip4.as_u32;
  		}
  
  	      vlib_buffer_copy_trace_flag (vm, p0, bi0);
  	      b0 = vlib_get_buffer (vm, bi0);
  	      vnet_buffer (b0)->sw_if_index[VLIB_TX] = sw_if_index0;
  
  	      vlib_buffer_advance (b0, -adj0->rewrite_header.data_bytes);
  
  	      vlib_set_next_frame_buffer (vm, node,
  					  adj0->rewrite_header.next_index,
  					  bi0);
  	    }
  	}
  
        vlib_put_next_frame (vm, node, IP4_ARP_NEXT_DROP, n_left_to_next_drop);
      }
  
    return frame->n_vectors;
  }
  
  static uword
  ip4_arp (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
  {
    return (ip4_arp_inline (vm, node, frame, 0));
  }
  
  static uword
  ip4_glean (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
  {
    return (ip4_arp_inline (vm, node, frame, 1));
  }
  
  static char *ip4_arp_error_strings[] = {
    [IP4_ARP_ERROR_DROP] = "address overflow drops",
    [IP4_ARP_ERROR_REQUEST_SENT] = "ARP requests sent",
    [IP4_ARP_ERROR_NON_ARP_ADJ] = "ARPs to non-ARP adjacencies",
    [IP4_ARP_ERROR_REPLICATE_DROP] = "ARP replication completed",
    [IP4_ARP_ERROR_REPLICATE_FAIL] = "ARP replication failed",
    [IP4_ARP_ERROR_NO_SOURCE_ADDRESS] = "no source address for ARP request",
  };
  
  VLIB_REGISTER_NODE (ip4_arp_node) =
  {
    .function = ip4_arp,.name = "ip4-arp",.vector_size =
      sizeof (u32),.format_trace = format_ip4_forward_next_trace,.n_errors =
      ARRAY_LEN (ip4_arp_error_strings),.error_strings =
      ip4_arp_error_strings,.n_next_nodes = IP4_ARP_N_NEXT,.next_nodes =
    {
    [IP4_ARP_NEXT_DROP] = "error-drop",}
  ,};
  
  VLIB_REGISTER_NODE (ip4_glean_node) =
  {
    .function = ip4_glean,.name = "ip4-glean",.vector_size =
      sizeof (u32),.format_trace = format_ip4_forward_next_trace,.n_errors =
      ARRAY_LEN (ip4_arp_error_strings),.error_strings =
      ip4_arp_error_strings,.n_next_nodes = IP4_ARP_N_NEXT,.next_nodes =
    {
    [IP4_ARP_NEXT_DROP] = "error-drop",}
  ,};
  
  #define foreach_notrace_ip4_arp_error           \
  _(DROP)                                         \
  _(REQUEST_SENT)                                 \
  _(REPLICATE_DROP)                               \
  _(REPLICATE_FAIL)
  
  clib_error_t *
  arp_notrace_init (vlib_main_t * vm)
  {
    vlib_node_runtime_t *rt = vlib_node_get_runtime (vm, ip4_arp_node.index);
  
    /* don't trace ARP request packets */
  #define _(a)                                    \
      vnet_pcap_drop_trace_filter_add_del         \
          (rt->errors[IP4_ARP_ERROR_##a],         \
           1 /* is_add */);
    foreach_notrace_ip4_arp_error;
  #undef _
    return 0;
  }
  
  VLIB_INIT_FUNCTION (arp_notrace_init);
  
  
  /* Send an ARP request to see if given destination is reachable on given interface. */
  clib_error_t *
  ip4_probe_neighbor (vlib_main_t * vm, ip4_address_t * dst, u32 sw_if_index)
  {
    vnet_main_t *vnm = vnet_get_main ();
    ip4_main_t *im = &ip4_main;
    ethernet_arp_header_t *h;
    ip4_address_t *src;
    ip_interface_address_t *ia;
    ip_adjacency_t *adj;
    vnet_hw_interface_t *hi;
    vnet_sw_interface_t *si;
    vlib_buffer_t *b;
    u32 bi = 0;
  
    si = vnet_get_sw_interface (vnm, sw_if_index);
  
    if (!(si->flags & VNET_SW_INTERFACE_FLAG_ADMIN_UP))
      {
        return clib_error_return (0, "%U: interface %U down",
  				format_ip4_address, dst,
  				format_vnet_sw_if_index_name, vnm,
  				sw_if_index);
      }
  
    src =
      ip4_interface_address_matching_destination (im, dst, sw_if_index, &ia);
    if (!src)
      {
        vnm->api_errno = VNET_API_ERROR_NO_MATCHING_INTERFACE;
        return clib_error_return
  	(0,
  	 "no matching interface address for destination %U (interface %U)",
  	 format_ip4_address, dst, format_vnet_sw_if_index_name, vnm,
  	 sw_if_index);
      }
  
    adj = ip_get_adjacency (&im->lookup_main, ia->neighbor_probe_adj_index);
  
    h =
      vlib_packet_template_get_packet (vm,
  				     &im->ip4_arp_request_packet_template,
  				     &bi);
  
    hi = vnet_get_sup_hw_interface (vnm, sw_if_index);
  
    clib_memcpy (h->ip4_over_ethernet[0].ethernet, hi->hw_address,
  	       sizeof (h->ip4_over_ethernet[0].ethernet));
  
    h->ip4_over_ethernet[0].ip4 = src[0];
    h->ip4_over_ethernet[1].ip4 = dst[0];
  
    b = vlib_get_buffer (vm, bi);
    vnet_buffer (b)->sw_if_index[VLIB_RX] =
      vnet_buffer (b)->sw_if_index[VLIB_TX] = sw_if_index;
  
    /* Add encapsulation string for software interface (e.g. ethernet header). */
    vnet_rewrite_one_header (adj[0], h, sizeof (ethernet_header_t));
    vlib_buffer_advance (b, -adj->rewrite_header.data_bytes);
  
    {
      vlib_frame_t *f = vlib_get_frame_to_node (vm, hi->output_node_index);
      u32 *to_next = vlib_frame_vector_args (f);
      to_next[0] = bi;
      f->n_vectors = 1;
      vlib_put_frame_to_node (vm, hi->output_node_index, f);
    }
  
    return /* no error */ 0;
  }
  
  typedef enum
  {
    IP4_REWRITE_NEXT_DROP,
    IP4_REWRITE_NEXT_ICMP_ERROR,
  } ip4_rewrite_next_t;
  
  always_inline uword
  ip4_rewrite_inline (vlib_main_t * vm,
  		    vlib_node_runtime_t * node,
  		    vlib_frame_t * frame, int is_midchain, int is_mcast)
  {
    ip_lookup_main_t *lm = &ip4_main.lookup_main;
    u32 *from = vlib_frame_vector_args (frame);
    u32 n_left_from, n_left_to_next, *to_next, next_index;
    vlib_node_runtime_t *error_node =
      vlib_node_get_runtime (vm, ip4_input_node.index);
  
    n_left_from = frame->n_vectors;
    next_index = node->cached_next_index;
    u32 cpu_index = os_get_cpu_number ();
  
    while (n_left_from > 0)
      {
        vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
  
        while (n_left_from >= 4 && n_left_to_next >= 2)
  	{
  	  ip_adjacency_t *adj0, *adj1;
  	  vlib_buffer_t *p0, *p1;
  	  ip4_header_t *ip0, *ip1;
  	  u32 pi0, rw_len0, next0, error0, checksum0, adj_index0;
  	  u32 pi1, rw_len1, next1, error1, checksum1, adj_index1;
  	  u32 tx_sw_if_index0, tx_sw_if_index1;
  
  	  /* Prefetch next iteration. */
  	  {
  	    vlib_buffer_t *p2, *p3;
  
  	    p2 = vlib_get_buffer (vm, from[2]);
  	    p3 = vlib_get_buffer (vm, from[3]);
  
  	    vlib_prefetch_buffer_header (p2, STORE);
  	    vlib_prefetch_buffer_header (p3, STORE);
  
  	    CLIB_PREFETCH (p2->data, sizeof (ip0[0]), STORE);
  	    CLIB_PREFETCH (p3->data, sizeof (ip0[0]), STORE);
  	  }
  
  	  pi0 = to_next[0] = from[0];
  	  pi1 = to_next[1] = from[1];
  
  	  from += 2;
  	  n_left_from -= 2;
  	  to_next += 2;
  	  n_left_to_next -= 2;
  
  	  p0 = vlib_get_buffer (vm, pi0);
  	  p1 = vlib_get_buffer (vm, pi1);
  
  	  adj_index0 = vnet_buffer (p0)->ip.adj_index[VLIB_TX];
  	  adj_index1 = vnet_buffer (p1)->ip.adj_index[VLIB_TX];
  
  	  /* We should never rewrite a pkt using the MISS adjacency */
  	  ASSERT (adj_index0 && adj_index1);
  
  	  ip0 = vlib_buffer_get_current (p0);
  	  ip1 = vlib_buffer_get_current (p1);
  
  	  error0 = error1 = IP4_ERROR_NONE;
  	  next0 = next1 = IP4_REWRITE_NEXT_DROP;
  
  	  /* Decrement TTL & update checksum.
  	     Works either endian, so no need for byte swap. */
  	  if (PREDICT_TRUE (!(p0->flags & VNET_BUFFER_LOCALLY_ORIGINATED)))
  	    {
  	      i32 ttl0 = ip0->ttl;
  
  	      /* Input node should have reject packets with ttl 0. */
  	      ASSERT (ip0->ttl > 0);
  
  	      checksum0 = ip0->checksum + clib_host_to_net_u16 (0x0100);
  	      checksum0 += checksum0 >= 0xffff;
  
  	      ip0->checksum = checksum0;
  	      ttl0 -= 1;
  	      ip0->ttl = ttl0;
  
  	      /*
  	       * If the ttl drops below 1 when forwarding, generate
  	       * an ICMP response.
  	       */
  	      if (PREDICT_FALSE (ttl0 <= 0))
  		{
  		  error0 = IP4_ERROR_TIME_EXPIRED;
  		  vnet_buffer (p0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
  		  icmp4_error_set_vnet_buffer (p0, ICMP4_time_exceeded,
  					       ICMP4_time_exceeded_ttl_exceeded_in_transit,
  					       0);
  		  next0 = IP4_REWRITE_NEXT_ICMP_ERROR;
  		}
  
  	      /* Verify checksum. */
  	      ASSERT (ip0->checksum == ip4_header_checksum (ip0));
  	    }
  	  else
  	    {
  	      p0->flags &= ~VNET_BUFFER_LOCALLY_ORIGINATED;
  	    }
  	  if (PREDICT_TRUE (!(p1->flags & VNET_BUFFER_LOCALLY_ORIGINATED)))
  	    {
  	      i32 ttl1 = ip1->ttl;
  
  	      /* Input node should have reject packets with ttl 0. */
  	      ASSERT (ip1->ttl > 0);
  
  	      checksum1 = ip1->checksum + clib_host_to_net_u16 (0x0100);
  	      checksum1 += checksum1 >= 0xffff;
  
  	      ip1->checksum = checksum1;
  	      ttl1 -= 1;
  	      ip1->ttl = ttl1;
  
  	      /*
  	       * If the ttl drops below 1 when forwarding, generate
  	       * an ICMP response.
  	       */
  	      if (PREDICT_FALSE (ttl1 <= 0))
  		{
  		  error1 = IP4_ERROR_TIME_EXPIRED;
  		  vnet_buffer (p1)->sw_if_index[VLIB_TX] = (u32) ~ 0;
  		  icmp4_error_set_vnet_buffer (p1, ICMP4_time_exceeded,
  					       ICMP4_time_exceeded_ttl_exceeded_in_transit,
  					       0);
  		  next1 = IP4_REWRITE_NEXT_ICMP_ERROR;
  		}
  
  	      /* Verify checksum. */
  	      ASSERT (ip0->checksum == ip4_header_checksum (ip0));
  	      ASSERT (ip1->checksum == ip4_header_checksum (ip1));
  	    }
  	  else
  	    {
  	      p1->flags &= ~VNET_BUFFER_LOCALLY_ORIGINATED;
  	    }
  
  	  /* Rewrite packet header and updates lengths. */
  	  adj0 = ip_get_adjacency (lm, adj_index0);
  	  adj1 = ip_get_adjacency (lm, adj_index1);
  
  	  /* Worth pipelining. No guarantee that adj0,1 are hot... */
  	  rw_len0 = adj0[0].rewrite_header.data_bytes;
  	  rw_len1 = adj1[0].rewrite_header.data_bytes;
  	  vnet_buffer (p0)->ip.save_rewrite_length = rw_len0;
  	  vnet_buffer (p1)->ip.save_rewrite_length = rw_len1;
  
  	  /* Check MTU of outgoing interface. */
  	  error0 =
  	    (vlib_buffer_length_in_chain (vm, p0) >
  	     adj0[0].
  	     rewrite_header.max_l3_packet_bytes ? IP4_ERROR_MTU_EXCEEDED :
  	     error0);
  	  error1 =
  	    (vlib_buffer_length_in_chain (vm, p1) >
  	     adj1[0].
  	     rewrite_header.max_l3_packet_bytes ? IP4_ERROR_MTU_EXCEEDED :
  	     error1);
  
  	  /*
  	   * pre-fetch the per-adjacency counters
  	   */
  	  vlib_prefetch_combined_counter (&adjacency_counters,
  					  cpu_index, adj_index0);
  	  vlib_prefetch_combined_counter (&adjacency_counters,
  					  cpu_index, adj_index1);
  
  	  /* Don't adjust the buffer for ttl issue; icmp-error node wants
  	   * to see the IP headerr */
  	  if (PREDICT_TRUE (error0 == IP4_ERROR_NONE))
  	    {
  	      next0 = adj0[0].rewrite_header.next_index;
  	      p0->current_data -= rw_len0;
  	      p0->current_length += rw_len0;
  	      tx_sw_if_index0 = adj0[0].rewrite_header.sw_if_index;
  	      vnet_buffer (p0)->sw_if_index[VLIB_TX] = tx_sw_if_index0;
  
  	      vnet_feature_arc_start (lm->output_feature_arc_index,
  				      tx_sw_if_index0, &next0, p0);
  	    }
  	  if (PREDICT_TRUE (error1 == IP4_ERROR_NONE))
  	    {
  	      next1 = adj1[0].rewrite_header.next_index;
  	      p1->current_data -= rw_len1;
  	      p1->current_length += rw_len1;
  
  	      tx_sw_if_index1 = adj1[0].rewrite_header.sw_if_index;
  	      vnet_buffer (p1)->sw_if_index[VLIB_TX] = tx_sw_if_index1;
  
  	      vnet_feature_arc_start (lm->output_feature_arc_index,
  				      tx_sw_if_index1, &next1, p1);
  	    }
  
  	  /* Guess we are only writing on simple Ethernet header. */
  	  vnet_rewrite_two_headers (adj0[0], adj1[0],
  				    ip0, ip1, sizeof (ethernet_header_t));
  
  	  /*
  	   * Bump the per-adjacency counters
  	   */
  	  vlib_increment_combined_counter
  	    (&adjacency_counters,
  	     cpu_index,
  	     adj_index0, 1, vlib_buffer_length_in_chain (vm, p0) + rw_len0);
  
  	  vlib_increment_combined_counter
  	    (&adjacency_counters,
  	     cpu_index,
  	     adj_index1, 1, vlib_buffer_length_in_chain (vm, p1) + rw_len1);
  
  	  if (is_midchain)
  	    {
  	      adj0->sub_type.midchain.fixup_func (vm, adj0, p0);
  	      adj1->sub_type.midchain.fixup_func (vm, adj1, p1);
  	    }
  	  if (is_mcast)
  	    {
  	      /*
  	       * copy bytes from the IP address into the MAC rewrite
  	       */
  	      vnet_fixup_one_header (adj0[0], &ip0->dst_address, ip0, 1);
  	      vnet_fixup_one_header (adj1[0], &ip1->dst_address, ip1, 1);
  	    }
  
  	  vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
  					   to_next, n_left_to_next,
  					   pi0, pi1, next0, next1);
  	}
  
        while (n_left_from > 0 && n_left_to_next > 0)
  	{
  	  ip_adjacency_t *adj0;
  	  vlib_buffer_t *p0;
  	  ip4_header_t *ip0;
  	  u32 pi0, rw_len0, adj_index0, next0, error0, checksum0;
  	  u32 tx_sw_if_index0;
  
  	  pi0 = to_next[0] = from[0];
  
  	  p0 = vlib_get_buffer (vm, pi0);
  
  	  adj_index0 = vnet_buffer (p0)->ip.adj_index[VLIB_TX];
  
  	  /* We should never rewrite a pkt using the MISS adjacency */
  	  ASSERT (adj_index0);
  
  	  adj0 = ip_get_adjacency (lm, adj_index0);
  
  	  ip0 = vlib_buffer_get_current (p0);
  
  	  error0 = IP4_ERROR_NONE;
  	  next0 = IP4_REWRITE_NEXT_DROP;	/* drop on error */
  
  	  /* Decrement TTL & update checksum. */
  	  if (PREDICT_TRUE (!(p0->flags & VNET_BUFFER_LOCALLY_ORIGINATED)))
  	    {
  	      i32 ttl0 = ip0->ttl;
  
  	      checksum0 = ip0->checksum + clib_host_to_net_u16 (0x0100);
  
  	      checksum0 += checksum0 >= 0xffff;
  
  	      ip0->checksum = checksum0;
  
  	      ASSERT (ip0->ttl > 0);
  
  	      ttl0 -= 1;
  
  	      ip0->ttl = ttl0;
  
  	      ASSERT (ip0->checksum == ip4_header_checksum (ip0));
  
  	      if (PREDICT_FALSE (ttl0 <= 0))
  		{
  		  /*
  		   * If the ttl drops below 1 when forwarding, generate
  		   * an ICMP response.
  		   */
  		  error0 = IP4_ERROR_TIME_EXPIRED;
  		  next0 = IP4_REWRITE_NEXT_ICMP_ERROR;
  		  vnet_buffer (p0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
  		  icmp4_error_set_vnet_buffer (p0, ICMP4_time_exceeded,
  					       ICMP4_time_exceeded_ttl_exceeded_in_transit,
  					       0);
  		}
  	    }
  	  else
  	    {
  	      p0->flags &= ~VNET_BUFFER_LOCALLY_ORIGINATED;
  	    }
  
  	  vlib_prefetch_combined_counter (&adjacency_counters,
  					  cpu_index, adj_index0);
  
  	  /* Guess we are only writing on simple Ethernet header. */
  	  vnet_rewrite_one_header (adj0[0], ip0, sizeof (ethernet_header_t));
  	  if (is_mcast)
  	    {
  	      /*
  	       * copy bytes from the IP address into the MAC rewrite
  	       */
  	      vnet_fixup_one_header (adj0[0], &ip0->dst_address, ip0, 1);
  	    }
  
  	  /* Update packet buffer attributes/set output interface. */
  	  rw_len0 = adj0[0].rewrite_header.data_bytes;
  	  vnet_buffer (p0)->ip.save_rewrite_length = rw_len0;
  
  	  vlib_increment_combined_counter
  	    (&adjacency_counters,
  	     cpu_index,
  	     adj_index0, 1, vlib_buffer_length_in_chain (vm, p0) + rw_len0);
  
  	  /* Check MTU of outgoing interface. */
  	  error0 = (vlib_buffer_length_in_chain (vm, p0)
  		    > adj0[0].rewrite_header.max_l3_packet_bytes
  		    ? IP4_ERROR_MTU_EXCEEDED : error0);
  
  	  p0->error = error_node->errors[error0];
  
  	  /* Don't adjust the buffer for ttl issue; icmp-error node wants
  	   * to see the IP headerr */
  	  if (PREDICT_TRUE (error0 == IP4_ERROR_NONE))
  	    {
  	      p0->current_data -= rw_len0;
  	      p0->current_length += rw_len0;
  	      tx_sw_if_index0 = adj0[0].rewrite_header.sw_if_index;
  
  	      vnet_buffer (p0)->sw_if_index[VLIB_TX] = tx_sw_if_index0;
  	      next0 = adj0[0].rewrite_header.next_index;
  
  	      if (is_midchain)
  		{
  		  adj0->sub_type.midchain.fixup_func (vm, adj0, p0);
  		}
  
  	      vnet_feature_arc_start (lm->output_feature_arc_index,
  				      tx_sw_if_index0, &next0, p0);
  
  	    }
  
  	  from += 1;
  	  n_left_from -= 1;
  	  to_next += 1;
  	  n_left_to_next -= 1;
  
  	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
  					   to_next, n_left_to_next,
  					   pi0, next0);
  	}
  
        vlib_put_next_frame (vm, node, next_index, n_left_to_next);
      }
  
    /* Need to do trace after rewrites to pick up new packet data. */
    if (node->flags & VLIB_NODE_FLAG_TRACE)
      ip4_forward_next_trace (vm, node, frame, VLIB_TX);
  
    return frame->n_vectors;
  }
  
  
  /** @brief IPv4 rewrite node.
      @node ip4-rewrite
  
      This is the IPv4 transit-rewrite node: decrement TTL, fix the ipv4
      header checksum, fetch the ip adjacency, check the outbound mtu,
      apply the adjacency rewrite, and send pkts to the adjacency
      rewrite header's rewrite_next_index.
  
      @param vm vlib_main_t corresponding to the current thread
      @param node vlib_node_runtime_t
      @param frame vlib_frame_t whose contents should be dispatched
  
      @par Graph mechanics: buffer metadata, next index usage
  
      @em Uses:
      - <code>vnet_buffer(b)->ip.adj_index[VLIB_TX]</code>
          - the rewrite adjacency index
      - <code>adj->lookup_next_index</code>
          - Must be IP_LOOKUP_NEXT_REWRITE or IP_LOOKUP_NEXT_ARP, otherwise
            the packet will be dropped.
      - <code>adj->rewrite_header</code>
          - Rewrite string length, rewrite string, next_index
  
      @em Sets:
      - <code>b->current_data, b->current_length</code>
          - Updated net of applying the rewrite string
  
      <em>Next Indices:</em>
      - <code> adj->rewrite_header.next_index </code>
        or @c error-drop
  */
  static uword
  ip4_rewrite (vlib_main_t * vm,
  	     vlib_node_runtime_t * node, vlib_frame_t * frame)
  {
    return ip4_rewrite_inline (vm, node, frame, 0, 0);
  }
  
  static uword
  ip4_midchain (vlib_main_t * vm,
  	      vlib_node_runtime_t * node, vlib_frame_t * frame)
  {
    return ip4_rewrite_inline (vm, node, frame, 1, 0);
  }
  
  static uword
  ip4_rewrite_mcast (vlib_main_t * vm,
  		   vlib_node_runtime_t * node, vlib_frame_t * frame)
  {
    return ip4_rewrite_inline (vm, node, frame, 0, 1);
  }
  
  /* *INDENT-OFF* */
  VLIB_REGISTER_NODE (ip4_rewrite_node) = {
    .function = ip4_rewrite,
    .name = "ip4-rewrite",
    .vector_size = sizeof (u32),
  
    .format_trace = format_ip4_rewrite_trace,
  
    .n_next_nodes = 2,
    .next_nodes = {
      [IP4_REWRITE_NEXT_DROP] = "error-drop",
      [IP4_REWRITE_NEXT_ICMP_ERROR] = "ip4-icmp-error",
    },
  };
  VLIB_NODE_FUNCTION_MULTIARCH (ip4_rewrite_node, ip4_rewrite)
  
  VLIB_REGISTER_NODE (ip4_rewrite_mcast_node) = {
    .function = ip4_rewrite_mcast,
    .name = "ip4-rewrite-mcast",
    .vector_size = sizeof (u32),
  
    .format_trace = format_ip4_rewrite_trace,
    .sibling_of = "ip4-rewrite",
  };
  VLIB_NODE_FUNCTION_MULTIARCH (ip4_rewrite_mcast_node, ip4_rewrite_mcast)
  
  VLIB_REGISTER_NODE (ip4_midchain_node) = {
    .function = ip4_midchain,
    .name = "ip4-midchain",
    .vector_size = sizeof (u32),
    .format_trace = format_ip4_forward_next_trace,
    .sibling_of =  "ip4-rewrite",
  };
  VLIB_NODE_FUNCTION_MULTIARCH (ip4_midchain_node, ip4_midchain);
  /* *INDENT-ON */
  
  static clib_error_t *
  add_del_interface_table (vlib_main_t * vm,
  			 unformat_input_t * input, vlib_cli_command_t * cmd)
  {
    vnet_main_t *vnm = vnet_get_main ();
    clib_error_t *error = 0;
    u32 sw_if_index, table_id;
  
    sw_if_index = ~0;
  
    if (!unformat_user (input, unformat_vnet_sw_interface, vnm, &sw_if_index))
      {
        error = clib_error_return (0, "unknown interface `%U'",
  				 format_unformat_error, input);
        goto done;
      }
  
    if (unformat (input, "%d", &table_id))
      ;
    else
      {
        error = clib_error_return (0, "expected table id `%U'",
  				 format_unformat_error, input);
        goto done;
      }
  
    {
      ip4_main_t *im = &ip4_main;
      u32 fib_index;
  
      fib_index = fib_table_find_or_create_and_lock (FIB_PROTOCOL_IP4,
  						   table_id);
  
      //
      // FIXME-LATER
      //  changing an interface's table has consequences for any connecteds
      //  and adj-fibs already installed.
      //
      vec_validate (im->fib_index_by_sw_if_index, sw_if_index);
      im->fib_index_by_sw_if_index[sw_if_index] = fib_index;
  
      fib_index = mfib_table_find_or_create_and_lock (FIB_PROTOCOL_IP4,
                                                     table_id);
      vec_validate (im->mfib_index_by_sw_if_index, sw_if_index);
      im->mfib_index_by_sw_if_index[sw_if_index] = fib_index;
    }
  
  done:
    return error;
  }
  
  /*?
   * Place the indicated interface into the supplied IPv4 FIB table (also known
   * as a VRF). If the FIB table does not exist, this command creates it. To
   * display the current IPv4 FIB table, use the command '<em>show ip fib</em>'.
   * FIB table will only be displayed if a route has been added to the table, or
   * an IP Address is assigned to an interface in the table (which adds a route
   * automatically).
   *
   * @note IP addresses added after setting the interface IP table end up in
   * the indicated FIB table. If the IP address is added prior to adding the
   * interface to the FIB table, it will NOT be part of the FIB table. Predictable
   * but potentially counter-intuitive results occur if you provision interface
   * addresses in multiple FIBs. Upon RX, packets will be processed in the last
   * IP table ID provisioned. It might be marginally useful to evade source RPF
   * drops to put an interface address into multiple FIBs.
   *
   * @cliexpar
   * Example of how to add an interface to an IPv4 FIB table (where 2 is the table-id):
   * @cliexcmd{set interface ip table GigabitEthernet2/0/0 2}
   ?*/
  /* *INDENT-OFF* */
  VLIB_CLI_COMMAND (set_interface_ip_table_command, static) =
  {
    .path = "set interface ip table",
    .function = add_del_interface_table,
    .short_help = "set interface ip table <interface> <table-id>",
  };
  /* *INDENT-ON* */
  
  int
  ip4_lookup_validate (ip4_address_t * a, u32 fib_index0)
  {
    ip4_fib_mtrie_t *mtrie0;
    ip4_fib_mtrie_leaf_t leaf0;
    u32 lbi0;
  
    mtrie0 = &ip4_fib_get (fib_index0)->mtrie;
  
    leaf0 = IP4_FIB_MTRIE_LEAF_ROOT;
    leaf0 = ip4_fib_mtrie_lookup_step (mtrie0, leaf0, a, 0);
    leaf0 = ip4_fib_mtrie_lookup_step (mtrie0, leaf0, a, 1);
    leaf0 = ip4_fib_mtrie_lookup_step (mtrie0, leaf0, a, 2);
    leaf0 = ip4_fib_mtrie_lookup_step (mtrie0, leaf0, a, 3);
  
    /* Handle default route. */
    leaf0 = (leaf0 == IP4_FIB_MTRIE_LEAF_EMPTY ? mtrie0->default_leaf : leaf0);
  
    lbi0 = ip4_fib_mtrie_leaf_get_adj_index (leaf0);
  
    return lbi0 == ip4_fib_table_lookup_lb (ip4_fib_get (fib_index0), a);
  }
  
  static clib_error_t *
  test_lookup_command_fn (vlib_main_t * vm,
  			unformat_input_t * input, vlib_cli_command_t * cmd)
  {
    ip4_fib_t *fib;
    u32 table_id = 0;
    f64 count = 1;
    u32 n;
    int i;
    ip4_address_t ip4_base_address;
    u64 errors = 0;
  
    while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
      {
        if (unformat (input, "table %d", &table_id))
  	{
  	  /* Make sure the entry exists. */
  	  fib = ip4_fib_get (table_id);
  	  if ((fib) && (fib->index != table_id))
  	    return clib_error_return (0, "<fib-index> %d does not exist",
  				      table_id);
  	}
        else if (unformat (input, "count %f", &count))
  	;
  
        else if (unformat (input, "%U",
  			 unformat_ip4_address, &ip4_base_address))
  	;
        else
  	return clib_error_return (0, "unknown input `%U'",
  				  format_unformat_error, input);
      }
  
    n = count;
  
    for (i = 0; i < n; i++)
      {
        if (!ip4_lookup_validate (&ip4_base_address, table_id))
  	errors++;
  
        ip4_base_address.as_u32 =
  	clib_host_to_net_u32 (1 +
  			      clib_net_to_host_u32 (ip4_base_address.as_u32));
      }
  
    if (errors)
      vlib_cli_output (vm, "%llu errors out of %d lookups\n", errors, n);
    else
      vlib_cli_output (vm, "No errors in %d lookups\n", n);
  
    return 0;
  }
  
  /*?
   * Perform a lookup of an IPv4 Address (or range of addresses) in the
   * given FIB table to determine if there is a conflict with the
   * adjacency table. The fib-id can be determined by using the
   * '<em>show ip fib</em>' command. If fib-id is not entered, default value
   * of 0 is used.
   *
   * @todo This command uses fib-id, other commands use table-id (not
   * just a name, they are different indexes). Would like to change this
   * to table-id for consistency.
   *
   * @cliexpar
   * Example of how to run the test lookup command:
   * @cliexstart{test lookup 172.16.1.1 table 1 count 2}
   * No errors in 2 lookups
   * @cliexend
  ?*/
  /* *INDENT-OFF* */
  VLIB_CLI_COMMAND (lookup_test_command, static) =
  {
    .path = "test lookup",
    .short_help = "test lookup <ipv4-addr> [table <fib-id>] [count <nn>]",
    .function = test_lookup_command_fn,
  };
  /* *INDENT-ON* */
  
  int
  vnet_set_ip4_flow_hash (u32 table_id, u32 flow_hash_config)
  {
    ip4_main_t *im4 = &ip4_main;
    ip4_fib_t *fib;
    uword *p = hash_get (im4->fib_index_by_table_id, table_id);
  
    if (p == 0)
      return VNET_API_ERROR_NO_SUCH_FIB;
  
    fib = ip4_fib_get (p[0]);
  
    fib->flow_hash_config = flow_hash_config;
    return 0;
  }
  
  static clib_error_t *
  set_ip_flow_hash_command_fn (vlib_main_t * vm,
  			     unformat_input_t * input,
  			     vlib_cli_command_t * cmd)
  {
    int matched = 0;
    u32 table_id = 0;
    u32 flow_hash_config = 0;
    int rv;
  
    while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
      {
        if (unformat (input, "table %d", &table_id))
  	matched = 1;
  #define _(a,v) \
      else if (unformat (input, #a)) { flow_hash_config |= v; matched=1;}
        foreach_flow_hash_bit
  #undef _
  	else
  	break;
      }
  
    if (matched == 0)
      return clib_error_return (0, "unknown input `%U'",
  			      format_unformat_error, input);
  
    rv = vnet_set_ip4_flow_hash (table_id, flow_hash_config);
    switch (rv)
      {
      case 0:
        break;
  
      case VNET_API_ERROR_NO_SUCH_FIB:
        return clib_error_return (0, "no such FIB table %d", table_id);
  
      default:
        clib_warning ("BUG: illegal flow hash config 0x%x", flow_hash_config);
        break;
      }
  
    return 0;
  }
  
  /*?
   * Configure the set of IPv4 fields used by the flow hash.
   *
   * @cliexpar
   * Example of how to set the flow hash on a given table:
   * @cliexcmd{set ip flow-hash table 7 dst sport dport proto}
   * Example of display the configured flow hash:
   * @cliexstart{show ip fib}
   * ipv4-VRF:0, fib_index 0, flow hash: src dst sport dport proto
   * 0.0.0.0/0
   *   unicast-ip4-chain
   *   [@0]: dpo-load-balance: [index:0 buckets:1 uRPF:0 to:[0:0]]
   *     [0] [@0]: dpo-drop ip6
   * 0.0.0.0/32
   *   unicast-ip4-chain
   *   [@0]: dpo-load-balance: [index:1 buckets:1 uRPF:1 to:[0:0]]
   *     [0] [@0]: dpo-drop ip6
   * 224.0.0.0/8
   *   unicast-ip4-chain
   *   [@0]: dpo-load-balance: [index:3 buckets:1 uRPF:3 to:[0:0]]
   *     [0] [@0]: dpo-drop ip6
   * 6.0.1.2/32
   *   unicast-ip4-chain
   *   [@0]: dpo-load-balance: [index:30 buckets:1 uRPF:29 to:[0:0]]
   *     [0] [@3]: arp-ipv4: via 6.0.0.1 af_packet0
   * 7.0.0.1/32
   *   unicast-ip4-chain
   *   [@0]: dpo-load-balance: [index:31 buckets:4 uRPF:30 to:[0:0]]
   *     [0] [@3]: arp-ipv4: via 6.0.0.2 af_packet0
   *     [1] [@3]: arp-ipv4: via 6.0.0.2 af_packet0
   *     [2] [@3]: arp-ipv4: via 6.0.0.2 af_packet0
   *     [3] [@3]: arp-ipv4: via 6.0.0.1 af_packet0
   * 240.0.0.0/8
   *   unicast-ip4-chain
   *   [@0]: dpo-load-balance: [index:2 buckets:1 uRPF:2 to:[0:0]]
   *     [0] [@0]: dpo-drop ip6
   * 255.255.255.255/32
   *   unicast-ip4-chain
   *   [@0]: dpo-load-balance: [index:4 buckets:1 uRPF:4 to:[0:0]]
   *     [0] [@0]: dpo-drop ip6
   * ipv4-VRF:7, fib_index 1, flow hash: dst sport dport proto
   * 0.0.0.0/0
   *   unicast-ip4-chain
   *   [@0]: dpo-load-balance: [index:12 buckets:1 uRPF:11 to:[0:0]]
   *     [0] [@0]: dpo-drop ip6
   * 0.0.0.0/32
   *   unicast-ip4-chain
   *   [@0]: dpo-load-balance: [index:13 buckets:1 uRPF:12 to:[0:0]]
   *     [0] [@0]: dpo-drop ip6
   * 172.16.1.0/24
   *   unicast-ip4-chain
   *   [@0]: dpo-load-balance: [index:17 buckets:1 uRPF:16 to:[0:0]]
   *     [0] [@4]: ipv4-glean: af_packet0
   * 172.16.1.1/32
   *   unicast-ip4-chain
   *   [@0]: dpo-load-balance: [index:18 buckets:1 uRPF:17 to:[1:84]]
   *     [0] [@2]: dpo-receive: 172.16.1.1 on af_packet0
   * 172.16.1.2/32
   *   unicast-ip4-chain
   *   [@0]: dpo-load-balance: [index:21 buckets:1 uRPF:20 to:[0:0]]
   *     [0] [@5]: ipv4 via 172.16.1.2 af_packet0: IP4: 02:fe:9e:70:7a:2b -> 26:a5:f6:9c:3a:36
   * 172.16.2.0/24
   *   unicast-ip4-chain
   *   [@0]: dpo-load-balance: [index:19 buckets:1 uRPF:18 to:[0:0]]
   *     [0] [@4]: ipv4-glean: af_packet1
   * 172.16.2.1/32
   *   unicast-ip4-chain
   *   [@0]: dpo-load-balance: [index:20 buckets:1 uRPF:19 to:[0:0]]
   *     [0] [@2]: dpo-receive: 172.16.2.1 on af_packet1
   * 224.0.0.0/8
   *   unicast-ip4-chain
   *   [@0]: dpo-load-balance: [index:15 buckets:1 uRPF:14 to:[0:0]]
   *     [0] [@0]: dpo-drop ip6
   * 240.0.0.0/8
   *   unicast-ip4-chain
   *   [@0]: dpo-load-balance: [index:14 buckets:1 uRPF:13 to:[0:0]]
   *     [0] [@0]: dpo-drop ip6
   * 255.255.255.255/32
   *   unicast-ip4-chain
   *   [@0]: dpo-load-balance: [index:16 buckets:1 uRPF:15 to:[0:0]]
   *     [0] [@0]: dpo-drop ip6
   * @cliexend
  ?*/
  /* *INDENT-OFF* */
  VLIB_CLI_COMMAND (set_ip_flow_hash_command, static) =
  {
    .path = "set ip flow-hash",
    .short_help =
    "set ip flow-hash table <table-id> [src] [dst] [sport] [dport] [proto] [reverse]",
    .function = set_ip_flow_hash_command_fn,
  };
  /* *INDENT-ON* */
  
  int
  vnet_set_ip4_classify_intfc (vlib_main_t * vm, u32 sw_if_index,
  			     u32 table_index)
  {
    vnet_main_t *vnm = vnet_get_main ();
    vnet_interface_main_t *im = &vnm->interface_main;
    ip4_main_t *ipm = &ip4_main;
    ip_lookup_main_t *lm = &ipm->lookup_main;
    vnet_classify_main_t *cm = &vnet_classify_main;
    ip4_address_t *if_addr;
  
    if (pool_is_free_index (im->sw_interfaces, sw_if_index))
      return VNET_API_ERROR_NO_MATCHING_INTERFACE;
  
    if (table_index != ~0 && pool_is_free_index (cm->tables, table_index))
      return VNET_API_ERROR_NO_SUCH_ENTRY;
  
    vec_validate (lm->classify_table_index_by_sw_if_index, sw_if_index);
    lm->classify_table_index_by_sw_if_index[sw_if_index] = table_index;
  
    if_addr = ip4_interface_first_address (ipm, sw_if_index, NULL);
  
    if (NULL != if_addr)
      {
        fib_prefix_t pfx = {
  	.fp_len = 32,
  	.fp_proto = FIB_PROTOCOL_IP4,
  	.fp_addr.ip4 = *if_addr,
        };
        u32 fib_index;
  
        fib_index = fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP4,
  						       sw_if_index);
  
  
        if (table_index != (u32) ~ 0)
  	{
  	  dpo_id_t dpo = DPO_INVALID;
  
  	  dpo_set (&dpo,
  		   DPO_CLASSIFY,
  		   DPO_PROTO_IP4,
  		   classify_dpo_create (DPO_PROTO_IP4, table_index));
  
  	  fib_table_entry_special_dpo_add (fib_index,
  					   &pfx,
  					   FIB_SOURCE_CLASSIFY,
  					   FIB_ENTRY_FLAG_NONE, &dpo);
  	  dpo_reset (&dpo);
  	}
        else
  	{
  	  fib_table_entry_special_remove (fib_index,
  					  &pfx, FIB_SOURCE_CLASSIFY);
  	}
      }
  
    return 0;
  }
  
  static clib_error_t *
  set_ip_classify_command_fn (vlib_main_t * vm,
  			    unformat_input_t * input,
  			    vlib_cli_command_t * cmd)
  {
    u32 table_index = ~0;
    int table_index_set = 0;
    u32 sw_if_index = ~0;
    int rv;
  
    while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
      {
        if (unformat (input, "table-index %d", &table_index))
  	table_index_set = 1;
        else if (unformat (input, "intfc %U", unformat_vnet_sw_interface,
  			 vnet_get_main (), &sw_if_index))
  	;
        else
  	break;
      }
  
    if (table_index_set == 0)
      return clib_error_return (0, "classify table-index must be specified");
  
    if (sw_if_index == ~0)
      return clib_error_return (0, "interface / subif must be specified");
  
    rv = vnet_set_ip4_classify_intfc (vm, sw_if_index, table_index);
  
    switch (rv)
      {
      case 0:
        break;
  
      case VNET_API_ERROR_NO_MATCHING_INTERFACE:
        return clib_error_return (0, "No such interface");
  
      case VNET_API_ERROR_NO_SUCH_ENTRY:
        return clib_error_return (0, "No such classifier table");
      }
    return 0;
  }
  
  /*?
   * Assign a classification table to an interface. The classification
   * table is created using the '<em>classify table</em>' and '<em>classify session</em>'
   * commands. Once the table is create, use this command to filter packets
   * on an interface.
   *
   * @cliexpar
   * Example of how to assign a classification table to an interface:
   * @cliexcmd{set ip classify intfc GigabitEthernet2/0/0 table-index 1}
  ?*/
  /* *INDENT-OFF* */
  VLIB_CLI_COMMAND (set_ip_classify_command, static) =
  {
      .path = "set ip classify",
      .short_help =
      "set ip classify intfc <interface> table-index <classify-idx>",
      .function = set_ip_classify_command_fn,
  };
  /* *INDENT-ON* */
  
  /*
   * fd.io coding-style-patch-verification: ON
   *
   * Local Variables:
   * eval: (c-set-style "gnu")
   * End:
   */
  