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/ip/ip_frag.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/load_balance_map.h>
  #include <vnet/dpo/classify_dpo.h>
  #include <vnet/mfib/mfib_table.h>	/* for mFIB table and entry creation */
  
  #include <vnet/ip/ip4_forward.h>
  #include <vnet/interface_output.h>
  
  /** @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).
  */
  VLIB_NODE_FN (ip4_lookup_node) (vlib_main_t * vm, vlib_node_runtime_t * node,
  				vlib_frame_t * frame)
  {
    return ip4_lookup_inline (vm, node, frame);
  }
  
  static u8 *format_ip4_lookup_trace (u8 * s, va_list * args);
  
  /* *INDENT-OFF* */
  VLIB_REGISTER_NODE (ip4_lookup_node) =
  {
    .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,
  };
  /* *INDENT-ON* */
  
  VLIB_NODE_FN (ip4_load_balance_node) (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;
    u32 thread_index = vm->thread_index;
    vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b = bufs;
    u16 nexts[VLIB_FRAME_SIZE], *next;
  
    from = vlib_frame_vector_args (frame);
    n_left = frame->n_vectors;
    next = nexts;
  
    vlib_get_buffers (vm, from, bufs, n_left);
  
    while (n_left >= 4)
      {
        const load_balance_t *lb0, *lb1;
        const ip4_header_t *ip0, *ip1;
        u32 lbi0, hc0, lbi1, hc1;
        const dpo_id_t *dpo0, *dpo1;
  
        /* Prefetch next iteration. */
        {
  	vlib_prefetch_buffer_header (b[2], LOAD);
  	vlib_prefetch_buffer_header (b[3], LOAD);
  
  	CLIB_PREFETCH (b[2]->data, sizeof (ip0[0]), LOAD);
  	CLIB_PREFETCH (b[3]->data, sizeof (ip0[0]), LOAD);
        }
  
        ip0 = vlib_buffer_get_current (b[0]);
        ip1 = vlib_buffer_get_current (b[1]);
        lbi0 = vnet_buffer (b[0])->ip.adj_index[VLIB_TX];
        lbi1 = vnet_buffer (b[1])->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 = hc1 = 0;
  
        if (PREDICT_FALSE (lb0->lb_n_buckets > 1))
  	{
  	  if (PREDICT_TRUE (vnet_buffer (b[0])->ip.flow_hash))
  	    {
  	      hc0 = vnet_buffer (b[0])->ip.flow_hash =
  		vnet_buffer (b[0])->ip.flow_hash >> 1;
  	    }
  	  else
  	    {
  	      hc0 = vnet_buffer (b[0])->ip.flow_hash =
  		ip4_compute_flow_hash (ip0, lb0->lb_hash_config);
  	    }
  	  dpo0 = load_balance_get_fwd_bucket
  	    (lb0, (hc0 & (lb0->lb_n_buckets_minus_1)));
  	}
        else
  	{
  	  dpo0 = load_balance_get_bucket_i (lb0, 0);
  	}
        if (PREDICT_FALSE (lb1->lb_n_buckets > 1))
  	{
  	  if (PREDICT_TRUE (vnet_buffer (b[1])->ip.flow_hash))
  	    {
  	      hc1 = vnet_buffer (b[1])->ip.flow_hash =
  		vnet_buffer (b[1])->ip.flow_hash >> 1;
  	    }
  	  else
  	    {
  	      hc1 = vnet_buffer (b[1])->ip.flow_hash =
  		ip4_compute_flow_hash (ip1, lb1->lb_hash_config);
  	    }
  	  dpo1 = load_balance_get_fwd_bucket
  	    (lb1, (hc1 & (lb1->lb_n_buckets_minus_1)));
  	}
        else
  	{
  	  dpo1 = load_balance_get_bucket_i (lb1, 0);
  	}
  
        next[0] = dpo0->dpoi_next_node;
        next[1] = dpo1->dpoi_next_node;
  
        vnet_buffer (b[0])->ip.adj_index[VLIB_TX] = dpo0->dpoi_index;
        vnet_buffer (b[1])->ip.adj_index[VLIB_TX] = dpo1->dpoi_index;
  
        vlib_increment_combined_counter
  	(cm, thread_index, lbi0, 1, vlib_buffer_length_in_chain (vm, b[0]));
        vlib_increment_combined_counter
  	(cm, thread_index, lbi1, 1, vlib_buffer_length_in_chain (vm, b[1]));
  
        b += 2;
        next += 2;
        n_left -= 2;
      }
  
    while (n_left > 0)
      {
        const load_balance_t *lb0;
        const ip4_header_t *ip0;
        const dpo_id_t *dpo0;
        u32 lbi0, hc0;
  
        ip0 = vlib_buffer_get_current (b[0]);
        lbi0 = vnet_buffer (b[0])->ip.adj_index[VLIB_TX];
  
        lb0 = load_balance_get (lbi0);
  
        hc0 = 0;
        if (PREDICT_FALSE (lb0->lb_n_buckets > 1))
  	{
  	  if (PREDICT_TRUE (vnet_buffer (b[0])->ip.flow_hash))
  	    {
  	      hc0 = vnet_buffer (b[0])->ip.flow_hash =
  		vnet_buffer (b[0])->ip.flow_hash >> 1;
  	    }
  	  else
  	    {
  	      hc0 = vnet_buffer (b[0])->ip.flow_hash =
  		ip4_compute_flow_hash (ip0, lb0->lb_hash_config);
  	    }
  	  dpo0 = load_balance_get_fwd_bucket
  	    (lb0, (hc0 & (lb0->lb_n_buckets_minus_1)));
  	}
        else
  	{
  	  dpo0 = load_balance_get_bucket_i (lb0, 0);
  	}
  
        next[0] = dpo0->dpoi_next_node;
        vnet_buffer (b[0])->ip.adj_index[VLIB_TX] = dpo0->dpoi_index;
  
        vlib_increment_combined_counter
  	(cm, thread_index, lbi0, 1, vlib_buffer_length_in_chain (vm, b[0]));
  
        b += 1;
        next += 1;
        n_left -= 1;
      }
  
    vlib_buffer_enqueue_to_next (vm, node, from, nexts, frame->n_vectors);
    if (node->flags & VLIB_NODE_FLAG_TRACE)
      ip4_forward_next_trace (vm, node, frame, VLIB_TX);
  
    return frame->n_vectors;
  }
  
  /* *INDENT-OFF* */
  VLIB_REGISTER_NODE (ip4_load_balance_node) =
  {
    .name = "ip4-load-balance",
    .vector_size = sizeof (u32),
    .sibling_of = "ip4-lookup",
    .format_trace = format_ip4_lookup_trace,
  };
  /* *INDENT-ON* */
  
  #ifndef CLIB_MARCH_VARIANT
  /* 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;
  }
  #endif
  
  static void
  ip4_add_subnet_bcast_route (u32 fib_index,
                              fib_prefix_t *pfx,
                              u32 sw_if_index)
  {
    vnet_sw_interface_flags_t iflags;
  
    iflags = vnet_sw_interface_get_flags(vnet_get_main(), sw_if_index);
  
    fib_table_entry_special_remove(fib_index,
                                   pfx,
                                   FIB_SOURCE_INTERFACE);
  
    if (iflags & VNET_SW_INTERFACE_FLAG_DIRECTED_BCAST)
      {
        fib_table_entry_update_one_path (fib_index, pfx,
                                         FIB_SOURCE_INTERFACE,
                                         FIB_ENTRY_FLAG_NONE,
                                         DPO_PROTO_IP4,
                                         /* No next-hop address */
                                         &ADJ_BCAST_ADDR,
                                         sw_if_index,
                                         // invalid FIB index
                                         ~0,
                                         1,
                                         // no out-label stack
                                         NULL,
                                         FIB_ROUTE_PATH_FLAG_NONE);
      }
    else
      {
          fib_table_entry_special_add(fib_index,
                                      pfx,
                                      FIB_SOURCE_INTERFACE,
                                      (FIB_ENTRY_FLAG_DROP |
                                       FIB_ENTRY_FLAG_LOOSE_URPF_EXEMPT));
      }
  }
  
  static void
  ip4_add_interface_prefix_routes (ip4_main_t *im,
  				 u32 sw_if_index,
  				 u32 fib_index,
  				 ip_interface_address_t * a)
  {
    ip_lookup_main_t *lm = &im->lookup_main;
    ip_interface_prefix_t *if_prefix;
    ip4_address_t *address = ip_interface_address_get_address (lm, a);
  
    ip_interface_prefix_key_t key = {
      .prefix = {
        .fp_len = a->address_length,
        .fp_proto = FIB_PROTOCOL_IP4,
        .fp_addr.ip4.as_u32 = address->as_u32 & im->fib_masks[a->address_length],
      },
      .sw_if_index = sw_if_index,
    };
  
    fib_prefix_t pfx_special = {
      .fp_proto = FIB_PROTOCOL_IP4,
    };
  
    /* If prefix already set on interface, just increment ref count & return */
    if_prefix = ip_get_interface_prefix (lm, &key);
    if (if_prefix)
      {
        if_prefix->ref_count += 1;
        return;
      }
  
    /* New prefix - allocate a pool entry, initialize it, add to the hash */
    pool_get (lm->if_prefix_pool, if_prefix);
    if_prefix->ref_count = 1;
    if_prefix->src_ia_index = a - lm->if_address_pool;
    clib_memcpy (&if_prefix->key, &key, sizeof (key));
    mhash_set (&lm->prefix_to_if_prefix_index, &key,
  	     if_prefix - lm->if_prefix_pool, 0 /* old value */);
  
    /* length <= 30 - add glean, drop first address, maybe drop bcast address */
    if (a->address_length <= 30)
      {
        pfx_special.fp_len = a->address_length;
        pfx_special.fp_addr.ip4.as_u32 = address->as_u32;
  
        /* set the glean route for the prefix */
        fib_table_entry_update_one_path (fib_index, &pfx_special,
  				       FIB_SOURCE_INTERFACE,
  				       (FIB_ENTRY_FLAG_CONNECTED |
  					FIB_ENTRY_FLAG_ATTACHED),
  				       DPO_PROTO_IP4,
  				       /* No next-hop address */
  				       NULL,
  				       sw_if_index,
                                         /* invalid FIB index */
                                         ~0,
                                         1,
                                         /* no out-label stack */
                                         NULL,
                                         FIB_ROUTE_PATH_FLAG_NONE);
  
        /* set a drop route for the base address of the prefix */
        pfx_special.fp_len = 32;
        pfx_special.fp_addr.ip4.as_u32 =
  	address->as_u32 & im->fib_masks[a->address_length];
  
        if (pfx_special.fp_addr.ip4.as_u32 != address->as_u32)
  	fib_table_entry_special_add (fib_index, &pfx_special,
  				     FIB_SOURCE_INTERFACE,
  				     (FIB_ENTRY_FLAG_DROP |
  				      FIB_ENTRY_FLAG_LOOSE_URPF_EXEMPT));
  
        /* set a route for the broadcast address of the prefix */
        pfx_special.fp_len = 32;
        pfx_special.fp_addr.ip4.as_u32 =
  	address->as_u32 | ~im->fib_masks[a->address_length];
        if (pfx_special.fp_addr.ip4.as_u32 != address->as_u32)
  	ip4_add_subnet_bcast_route (fib_index, &pfx_special, sw_if_index);
  
  
      }
    /* length == 31 - add an attached route for the other address */
    else if (a->address_length == 31)
      {
        pfx_special.fp_len = 32;
        pfx_special.fp_addr.ip4.as_u32 =
  	address->as_u32 ^ clib_host_to_net_u32(1);
  
        fib_table_entry_update_one_path (fib_index, &pfx_special,
  				       FIB_SOURCE_INTERFACE,
  				       (FIB_ENTRY_FLAG_ATTACHED),
  				       DPO_PROTO_IP4,
  				       &pfx_special.fp_addr,
  				       sw_if_index,
                                         /* invalid FIB index */
                                         ~0,
                                         1,
                                         NULL,
                                         FIB_ROUTE_PATH_FLAG_NONE);
      }
  }
  
  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 = 32,
      .fp_proto = FIB_PROTOCOL_IP4,
      .fp_addr.ip4 = *address,
    };
  
    /* set special routes for the prefix if needed */
    ip4_add_interface_prefix_routes (im, sw_if_index, fib_index, a);
  
    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),
                                     DPO_PROTO_IP4,
                                     &pfx.fp_addr,
                                     sw_if_index,
                                     // invalid FIB index
                                     ~0,
  				   1, NULL,
  				   FIB_ROUTE_PATH_FLAG_NONE);
  }
  
  static void
  ip4_del_interface_prefix_routes (ip4_main_t * im,
  				 u32 sw_if_index,
  				 u32 fib_index,
  				 ip4_address_t * address,
  				 u32 address_length)
  {
    ip_lookup_main_t *lm = &im->lookup_main;
    ip_interface_prefix_t *if_prefix;
  
    ip_interface_prefix_key_t key = {
      .prefix = {
        .fp_len = address_length,
        .fp_proto = FIB_PROTOCOL_IP4,
        .fp_addr.ip4.as_u32 = address->as_u32 & im->fib_masks[address_length],
      },
      .sw_if_index = sw_if_index,
    };
  
    fib_prefix_t pfx_special = {
      .fp_len = 32,
      .fp_proto = FIB_PROTOCOL_IP4,
    };
  
    if_prefix = ip_get_interface_prefix (lm, &key);
    if (!if_prefix)
      {
        clib_warning ("Prefix not found while deleting %U",
  		    format_ip4_address_and_length, address, address_length);
        return;
      }
  
    if_prefix->ref_count -= 1;
  
    /*
     * Routes need to be adjusted if:
     * - deleting last intf addr in prefix
     * - deleting intf addr used as default source address in glean adjacency
     *
     * We're done now otherwise
     */
    if ((if_prefix->ref_count > 0) &&
        !pool_is_free_index (lm->if_address_pool, if_prefix->src_ia_index))
      return;
  
    /* length <= 30, delete glean route, first address, last address */
    if (address_length <= 30)
      {
  
        /* remove glean route for prefix */
        pfx_special.fp_addr.ip4 = *address;
        pfx_special.fp_len = address_length;
        fib_table_entry_delete (fib_index, &pfx_special, FIB_SOURCE_INTERFACE);
  
        /* if no more intf addresses in prefix, remove other special routes */
        if (!if_prefix->ref_count)
  	{
  	  /* first address in prefix */
  	  pfx_special.fp_addr.ip4.as_u32 =
  	    address->as_u32 & im->fib_masks[address_length];
  	  pfx_special.fp_len = 32;
  
  	  if (pfx_special.fp_addr.ip4.as_u32 != address->as_u32)
  	  fib_table_entry_special_remove (fib_index,
  					  &pfx_special,
  					  FIB_SOURCE_INTERFACE);
  
  	  /* prefix broadcast address */
  	  pfx_special.fp_addr.ip4.as_u32 =
  	    address->as_u32 | ~im->fib_masks[address_length];
  	  pfx_special.fp_len = 32;
  
  	  if (pfx_special.fp_addr.ip4.as_u32 != address->as_u32)
  	  fib_table_entry_special_remove (fib_index,
  					  &pfx_special,
  					  FIB_SOURCE_INTERFACE);
  	}
        else
  	/* default source addr just got deleted, find another */
  	{
  	  ip_interface_address_t *new_src_ia = NULL;
  	  ip4_address_t *new_src_addr = NULL;
  
  	  new_src_addr =
  	    ip4_interface_address_matching_destination
  	      (im, address, sw_if_index, &new_src_ia);
  
  	  if_prefix->src_ia_index = new_src_ia - lm->if_address_pool;
  
  	  pfx_special.fp_len = address_length;
  	  pfx_special.fp_addr.ip4 = *new_src_addr;
  
  	  /* set new glean route for the prefix */
  	  fib_table_entry_update_one_path (fib_index, &pfx_special,
  					   FIB_SOURCE_INTERFACE,
  					   (FIB_ENTRY_FLAG_CONNECTED |
  					    FIB_ENTRY_FLAG_ATTACHED),
  					   DPO_PROTO_IP4,
  					   /* No next-hop address */
  					   NULL,
  					   sw_if_index,
  					   /* invalid FIB index */
  					   ~0,
  					   1,
  					   /* no out-label stack */
  					   NULL,
  					   FIB_ROUTE_PATH_FLAG_NONE);
  	  return;
  	}
      }
    /* length == 31, delete attached route for the other address */
    else if (address_length == 31)
      {
        pfx_special.fp_addr.ip4.as_u32 =
  	address->as_u32 ^ clib_host_to_net_u32(1);
  
        fib_table_entry_delete (fib_index, &pfx_special, FIB_SOURCE_INTERFACE);
      }
  
    mhash_unset (&lm->prefix_to_if_prefix_index, &key, 0 /* old_value */);
    pool_put (lm->if_prefix_pool, if_prefix);
  }
  
  static void
  ip4_del_interface_routes (u32 sw_if_index,
  			  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,
    };
  
    ip4_del_interface_prefix_routes (im, sw_if_index, fib_index,
  				   address, address_length);
  
    pfx.fp_len = 32;
    fib_table_entry_delete (fib_index, &pfx, FIB_SOURCE_INTERFACE);
  }
  
  #ifndef CLIB_MARCH_VARIANT
  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-not-enabled", sw_if_index,
  			       !is_enable, 0, 0);
  
  
    vnet_feature_enable_disable ("ip4-multicast", "ip4-not-enabled",
  			       sw_if_index, !is_enable, 0, 0);
  
    {
      ip4_enable_disable_interface_callback_t *cb;
      vec_foreach (cb, im->enable_disable_interface_callbacks)
        cb->function (im, cb->function_opaque, sw_if_index, is_enable);
    }
  }
  
  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;
  
    /* local0 interface doesn't support IP addressing  */
    if (sw_if_index == 0)
      {
        return
         clib_error_create ("local0 interface doesn't support IP addressing");
      }
  
    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);
  
    /*
     * 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 on any interface in this table. */
        ip_interface_address_t *ia;
        vnet_sw_interface_t *sif;
  
        pool_foreach(sif, vnm->interface_main.sw_interfaces,
        ({
            if (im->fib_index_by_sw_if_index[sw_if_index] ==
                im->fib_index_by_sw_if_index[sif->sw_if_index])
              {
                foreach_ip_interface_address
                  (&im->lookup_main, ia, sif->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))
                       {
  		       /* an intf may have >1 addr from the same prefix */
  		       if ((sw_if_index == sif->sw_if_index) &&
  			   (ia->address_length == address_length) &&
  			   (x->as_u32 != address->as_u32))
  		         continue;
  
  		       /* error if the length or intf was different */
                         vnm->api_errno = VNET_API_ERROR_DUPLICATE_IF_ADDRESS;
  
                         return
                           clib_error_create
                           ("failed to add %U on %U which conflicts with %U for interface %U",
                            format_ip4_address_and_length, address,
                            address_length,
  			  format_vnet_sw_if_index_name, vnm,
  			  sw_if_index,
                            format_ip4_address_and_length, x,
                            ia->address_length,
                            format_vnet_sw_if_index_name, vnm,
                            sif->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);
  
    /* intf addr routes are added/deleted on admin up/down */
    if (vnet_sw_interface_is_admin_up (vnm, sw_if_index))
      {
        if (is_del)
  	ip4_del_interface_routes (sw_if_index,
  				  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);
  }
  
  void
  ip4_directed_broadcast (u32 sw_if_index, u8 enable)
  {
    ip_interface_address_t *ia;
    ip4_main_t *im;
  
    im = &ip4_main;
  
    /*
     * when directed broadcast is enabled, the subnet braodcast route will forward
     * packets using an adjacency with a broadcast MAC. otherwise it drops
     */
    /* *INDENT-OFF* */
    foreach_ip_interface_address(&im->lookup_main, ia,
                                 sw_if_index, 0,
       ({
         if (ia->address_length <= 30)
           {
             ip4_address_t *ipa;
  
             ipa = ip_interface_address_get_address (&im->lookup_main, ia);
  
             fib_prefix_t pfx = {
               .fp_len = 32,
               .fp_proto = FIB_PROTOCOL_IP4,
               .fp_addr = {
                 .ip4.as_u32 = (ipa->as_u32 | ~im->fib_masks[ia->address_length]),
               },
             };
  
             ip4_add_subnet_bcast_route
               (fib_table_get_index_for_sw_if_index(FIB_PROTOCOL_IP4,
                                                    sw_if_index),
                &pfx, sw_if_index);
           }
       }));
    /* *INDENT-ON* */
  }
  #endif
  
  static clib_error_t *
  ip4_sw_interface_admin_up_down (vnet_main_t * vnm, u32 sw_if_index, u32 flags)
  {
    ip4_main_t *im = &ip4_main;
    ip_interface_address_t *ia;
    ip4_address_t *a;
    u32 is_admin_up, fib_index;
  
    /* Fill in lookup tables with default table (0). */
    vec_validate (im->fib_index_by_sw_if_index, sw_if_index);
  
    vec_validate_init_empty (im->
  			   lookup_main.if_address_pool_index_by_sw_if_index,
  			   sw_if_index, ~0);
  
    is_admin_up = (flags & VNET_SW_INTERFACE_FLAG_ADMIN_UP) != 0;
  
    fib_index = vec_elt (im->fib_index_by_sw_if_index, sw_if_index);
  
    /* *INDENT-OFF* */
    foreach_ip_interface_address (&im->lookup_main, ia, sw_if_index,
                                  0 /* honor unnumbered */,
    ({
      a = ip_interface_address_get_address (&im->lookup_main, ia);
      if (is_admin_up)
        ip4_add_interface_routes (sw_if_index,
  				im, fib_index,
  				ia);
      else
        ip4_del_interface_routes (sw_if_index,
  				im, fib_index,
  				a, ia->address_length);
    }));
    /* *INDENT-ON* */
  
    return 0;
  }
  
  VNET_SW_INTERFACE_ADMIN_UP_DOWN_FUNCTION (ip4_sw_interface_admin_up_down);
  
  /* 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"),
    .last_in_arc = "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 ("ipsec4-input-feature"),
  };
  
  VNET_FEATURE_INIT (ip4_ipsec, static) =
  {
    .arc_name = "ip4-unicast",
    .node_name = "ipsec4-input-feature",
    .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_not_enabled, static) =
  {
    .arc_name = "ip4-unicast",
    .node_name = "ip4-not-enabled",
    .runs_before = VNET_FEATURES ("ip4-lookup"),
  };
  
  VNET_FEATURE_INIT (ip4_lookup, static) =
  {
    .arc_name = "ip4-unicast",
    .node_name = "ip4-lookup",
    .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"),
    .last_in_arc = "ip4-mfib-forward-lookup",
    .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_mc_not_enabled, static) =
  {
    .arc_name = "ip4-multicast",
    .node_name = "ip4-not-enabled",
    .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 = 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", "ip4-dvr-dpo"),
    .last_in_arc = "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 ("ip4-outacl"),
  };
  
  VNET_FEATURE_INIT (ip4_outacl, static) =
  {
    .arc_name = "ip4-output",
    .node_name = "ip4-outacl",
    .runs_before = VNET_FEATURES ("ipsec4-output-feature"),
  };
  
  VNET_FEATURE_INIT (ip4_ipsec_output, static) =
  {
    .arc_name = "ip4-output",
    .node_name = "ipsec4-output-feature",
    .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);
  
    if (!is_add)
      {
        ip4_main_t *im4 = &ip4_main;
        ip_lookup_main_t *lm4 = &im4->lookup_main;
        ip_interface_address_t *ia = 0;
        ip4_address_t *address;
        vlib_main_t *vm = vlib_get_main ();
  
        vnet_sw_interface_update_unnumbered (sw_if_index, ~0, 0);
        /* *INDENT-OFF* */
        foreach_ip_interface_address (lm4, ia, sw_if_index, 0,
        ({
          address = ip_interface_address_get_address (lm4, ia);
          ip4_add_del_interface_address(vm, sw_if_index, address, ia->address_length, 1);
        }));
        /* *INDENT-ON* */
      }
  
    vnet_feature_enable_disable ("ip4-unicast", "ip4-not-enabled", sw_if_index,
  			       is_add, 0, 0);
  
    vnet_feature_enable_disable ("ip4-multicast", "ip4-not-enabled",
  			       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. */
  #ifndef CLIB_MARCH_VARIANT
  ip4_main_t ip4_main;
  #endif /* CLIB_MARCH_VARIANT */
  
  static 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;
    if ((error = vlib_call_init_function (vm, ip4_mtrie_module_init)))
      return (error);
    if ((error = vlib_call_init_function (vm, fib_module_init)))
      return error;
    if ((error = vlib_call_init_function (vm, mfib_module_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,
  				     FIB_SOURCE_DEFAULT_ROUTE);
    mfib_table_find_or_create_and_lock (FIB_PROTOCOL_IP4, 0,
  				      MFIB_SOURCE_DEFAULT_ROUTE);
  
    {
      pg_node_t *pn;
      pn = pg_get_node (ip4_lookup_node.index);
      pn->unformat_edit = unformat_pg_ip4_header;
    }
  
    {
      ethernet_arp_header_t h;
  
      clib_memset (&h, 0, sizeof (h));
  
  #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;
  
  #ifndef CLIB_MARCH_VARIANT
  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 *);
    u32 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;
  }
  #endif
  
  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 *);
    u32 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 *);
    u32 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,
  	      t->packet_data, sizeof (t->packet_data));
    return s;
  }
  
  #ifndef CLIB_MARCH_VARIANT
  /* 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_fast (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_fast (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_fast (t0->packet_data, vlib_buffer_get_current (b0),
  			    sizeof (t0->packet_data));
  	}
        from += 1;
        n_left -= 1;
      }
  }
  
  /* 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;
  
    /* 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));
  
    return ip_calculate_l4_checksum (vm, p0, sum0,
  				   payload_length_host_byte_order, (u8 *) ip0,
  				   ip_header_length, NULL);
  }
  
  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 |= (VNET_BUFFER_F_L4_CHECKSUM_COMPUTED
  		    | VNET_BUFFER_F_L4_CHECKSUM_CORRECT);
        return p0->flags;
      }
  
    sum16 = ip4_tcp_udp_compute_checksum (vm, p0, ip0);
  
    p0->flags |= (VNET_BUFFER_F_L4_CHECKSUM_COMPUTED
  		| ((sum16 == 0) << VNET_BUFFER_F_LOG2_L4_CHECKSUM_CORRECT));
  
    return p0->flags;
  }
  #endif
  
  /* *INDENT-OFF* */
  VNET_FEATURE_ARC_INIT (ip4_local) =
  {
    .arc_name  = "ip4-local",
    .start_nodes = VNET_FEATURES ("ip4-local"),
    .last_in_arc = "ip4-local-end-of-arc",
  };
  /* *INDENT-ON* */
  
  static inline void
  ip4_local_l4_csum_validate (vlib_main_t * vm, vlib_buffer_t * p,
  			    ip4_header_t * ip, u8 is_udp, u8 * error,
  			    u8 * good_tcp_udp)
  {
    u32 flags0;
    flags0 = ip4_tcp_udp_validate_checksum (vm, p);
    *good_tcp_udp = (flags0 & VNET_BUFFER_F_L4_CHECKSUM_CORRECT) != 0;
    if (is_udp)
      {
        udp_header_t *udp;
        u32 ip_len, udp_len;
        i32 len_diff;
        udp = ip4_next_header (ip);
        /* Verify UDP length. */
        ip_len = clib_net_to_host_u16 (ip->length);
        udp_len = clib_net_to_host_u16 (udp->length);
  
        len_diff = ip_len - udp_len;
        *good_tcp_udp &= len_diff >= 0;
        *error = len_diff < 0 ? IP4_ERROR_UDP_LENGTH : *error;
      }
  }
  
  #define ip4_local_csum_is_offloaded(_b)					\
      _b->flags & VNET_BUFFER_F_OFFLOAD_TCP_CKSUM				\
  	|| _b->flags & VNET_BUFFER_F_OFFLOAD_UDP_CKSUM
  
  #define ip4_local_need_csum_check(is_tcp_udp, _b) 			\
      (is_tcp_udp && !(_b->flags & VNET_BUFFER_F_L4_CHECKSUM_COMPUTED 	\
  	|| ip4_local_csum_is_offloaded (_b)))
  
  #define ip4_local_csum_is_valid(_b)					\
      (_b->flags & VNET_BUFFER_F_L4_CHECKSUM_CORRECT			\
  	|| (ip4_local_csum_is_offloaded (_b))) != 0
  
  static inline void
  ip4_local_check_l4_csum (vlib_main_t * vm, vlib_buffer_t * b,
  			 ip4_header_t * ih, u8 * error)
  {
    u8 is_udp, is_tcp_udp, good_tcp_udp;
  
    is_udp = ih->protocol == IP_PROTOCOL_UDP;
    is_tcp_udp = is_udp || ih->protocol == IP_PROTOCOL_TCP;
  
    if (PREDICT_FALSE (ip4_local_need_csum_check (is_tcp_udp, b)))
      ip4_local_l4_csum_validate (vm, b, ih, is_udp, error, &good_tcp_udp);
    else
      good_tcp_udp = ip4_local_csum_is_valid (b);
  
    ASSERT (IP4_ERROR_TCP_CHECKSUM + 1 == IP4_ERROR_UDP_CHECKSUM);
    *error = (is_tcp_udp && !good_tcp_udp
  	    ? IP4_ERROR_TCP_CHECKSUM + is_udp : *error);
  }
  
  static inline void
  ip4_local_check_l4_csum_x2 (vlib_main_t * vm, vlib_buffer_t ** b,
  			    ip4_header_t ** ih, u8 * error)
  {
    u8 is_udp[2], is_tcp_udp[2], good_tcp_udp[2];
  
    is_udp[0] = ih[0]->protocol == IP_PROTOCOL_UDP;
    is_udp[1] = ih[1]->protocol == IP_PROTOCOL_UDP;
  
    is_tcp_udp[0] = is_udp[0] || ih[0]->protocol == IP_PROTOCOL_TCP;
    is_tcp_udp[1] = is_udp[1] || ih[1]->protocol == IP_PROTOCOL_TCP;
  
    good_tcp_udp[0] = ip4_local_csum_is_valid (b[0]);
    good_tcp_udp[1] = ip4_local_csum_is_valid (b[1]);
  
    if (PREDICT_FALSE (ip4_local_need_csum_check (is_tcp_udp[0], b[0])
  		     || ip4_local_need_csum_check (is_tcp_udp[1], b[1])))
      {
        if (is_tcp_udp[0])
  	ip4_local_l4_csum_validate (vm, b[0], ih[0], is_udp[0], &error[0],
  				    &good_tcp_udp[0]);
        if (is_tcp_udp[1])
  	ip4_local_l4_csum_validate (vm, b[1], ih[1], is_udp[1], &error[1],
  				    &good_tcp_udp[1]);
      }
  
    error[0] = (is_tcp_udp[0] && !good_tcp_udp[0] ?
  	      IP4_ERROR_TCP_CHECKSUM + is_udp[0] : error[0]);
    error[1] = (is_tcp_udp[1] && !good_tcp_udp[1] ?
  	      IP4_ERROR_TCP_CHECKSUM + is_udp[1] : error[1]);
  }
  
  static inline void
  ip4_local_set_next_and_error (vlib_node_runtime_t * error_node,
  			      vlib_buffer_t * b, u16 * next, u8 error,
  			      u8 head_of_feature_arc)
  {
    u8 arc_index = vnet_feat_arc_ip4_local.feature_arc_index;
    u32 next_index;
  
    *next = error != IP4_ERROR_UNKNOWN_PROTOCOL ? IP_LOCAL_NEXT_DROP : *next;
    b->error = error ? error_node->errors[error] : 0;
    if (head_of_feature_arc)
      {
        next_index = *next;
        if (PREDICT_TRUE (error == (u8) IP4_ERROR_UNKNOWN_PROTOCOL))
  	{
  	  vnet_feature_arc_start (arc_index,
  				  vnet_buffer (b)->sw_if_index[VLIB_RX],
  				  &next_index, b);
  	  *next = next_index;
  	}
      }
  }
  
  typedef struct
  {
    ip4_address_t src;
    u32 lbi;
    u8 error;
    u8 first;
  } ip4_local_last_check_t;
  
  static inline void
  ip4_local_check_src (vlib_buffer_t * b, ip4_header_t * ip0,
  		     ip4_local_last_check_t * last_check, u8 * error0)
  {
    ip4_fib_mtrie_leaf_t leaf0;
    ip4_fib_mtrie_t *mtrie0;
    const dpo_id_t *dpo0;
    load_balance_t *lb0;
    u32 lbi0;
  
    vnet_buffer (b)->ip.fib_index =
      vnet_buffer (b)->sw_if_index[VLIB_TX] != ~0 ?
      vnet_buffer (b)->sw_if_index[VLIB_TX] : vnet_buffer (b)->ip.fib_index;
  
    /*
     * vnet_buffer()->ip.adj_index[VLIB_RX] will be set to the index of the
     *  adjacency for the destination address (the local interface address).
     * vnet_buffer()->ip.adj_index[VLIB_TX] will be set to the index of the
     *  adjacency for the source address (the remote sender's address)
     */
    if (PREDICT_FALSE (last_check->first ||
  		     (last_check->src.as_u32 != ip0->src_address.as_u32)))
      {
        mtrie0 = &ip4_fib_get (vnet_buffer (b)->ip.fib_index)->mtrie;
        leaf0 = ip4_fib_mtrie_lookup_step_one (mtrie0, &ip0->src_address);
        leaf0 = ip4_fib_mtrie_lookup_step (mtrie0, leaf0, &ip0->src_address, 2);
        leaf0 = ip4_fib_mtrie_lookup_step (mtrie0, leaf0, &ip0->src_address, 3);
        lbi0 = ip4_fib_mtrie_leaf_get_adj_index (leaf0);
  
        vnet_buffer (b)->ip.adj_index[VLIB_RX] =
  	vnet_buffer (b)->ip.adj_index[VLIB_TX];
        vnet_buffer (b)->ip.adj_index[VLIB_TX] = lbi0;
  
        lb0 = load_balance_get (lbi0);
        dpo0 = load_balance_get_bucket_i (lb0, 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);
  
        last_check->src.as_u32 = ip0->src_address.as_u32;
        last_check->lbi = lbi0;
        last_check->error = *error0;
      }
    else
      {
        vnet_buffer (b)->ip.adj_index[VLIB_RX] =
  	vnet_buffer (b)->ip.adj_index[VLIB_TX];
        vnet_buffer (b)->ip.adj_index[VLIB_TX] = last_check->lbi;
        *error0 = last_check->error;
        last_check->first = 0;
      }
  }
  
  static inline void
  ip4_local_check_src_x2 (vlib_buffer_t ** b, ip4_header_t ** ip,
  			ip4_local_last_check_t * last_check, u8 * error)
  {
    ip4_fib_mtrie_leaf_t leaf[2];
    ip4_fib_mtrie_t *mtrie[2];
    const dpo_id_t *dpo[2];
    load_balance_t *lb[2];
    u32 not_last_hit;
    u32 lbi[2];
  
    not_last_hit = last_check->first;
    not_last_hit |= ip[0]->src_address.as_u32 ^ last_check->src.as_u32;
    not_last_hit |= ip[1]->src_address.as_u32 ^ last_check->src.as_u32;
  
    vnet_buffer (b[0])->ip.fib_index =
      vnet_buffer (b[0])->sw_if_index[VLIB_TX] != ~0 ?
      vnet_buffer (b[0])->sw_if_index[VLIB_TX] :
      vnet_buffer (b[0])->ip.fib_index;
  
    vnet_buffer (b[1])->ip.fib_index =
      vnet_buffer (b[1])->sw_if_index[VLIB_TX] != ~0 ?
      vnet_buffer (b[1])->sw_if_index[VLIB_TX] :
      vnet_buffer (b[1])->ip.fib_index;
  
    /*
     * vnet_buffer()->ip.adj_index[VLIB_RX] will be set to the index of the
     *  adjacency for the destination address (the local interface address).
     * vnet_buffer()->ip.adj_index[VLIB_TX] will be set to the index of the
     *  adjacency for the source address (the remote sender's address)
     */
    if (PREDICT_FALSE (not_last_hit))
      {
        mtrie[0] = &ip4_fib_get (vnet_buffer (b[0])->ip.fib_index)->mtrie;
        mtrie[1] = &ip4_fib_get (vnet_buffer (b[1])->ip.fib_index)->mtrie;
  
        leaf[0] = ip4_fib_mtrie_lookup_step_one (mtrie[0], &ip[0]->src_address);
        leaf[1] = ip4_fib_mtrie_lookup_step_one (mtrie[1], &ip[1]->src_address);
  
        leaf[0] = ip4_fib_mtrie_lookup_step (mtrie[0], leaf[0],
  					   &ip[0]->src_address, 2);
        leaf[1] = ip4_fib_mtrie_lookup_step (mtrie[1], leaf[1],
  					   &ip[1]->src_address, 2);
  
        leaf[0] = ip4_fib_mtrie_lookup_step (mtrie[0], leaf[0],
  					   &ip[0]->src_address, 3);
        leaf[1] = ip4_fib_mtrie_lookup_step (mtrie[1], leaf[1],
  					   &ip[1]->src_address, 3);
  
        lbi[0] = ip4_fib_mtrie_leaf_get_adj_index (leaf[0]);
        lbi[1] = ip4_fib_mtrie_leaf_get_adj_index (leaf[1]);
  
        vnet_buffer (b[0])->ip.adj_index[VLIB_RX] =
  	vnet_buffer (b[0])->ip.adj_index[VLIB_TX];
        vnet_buffer (b[0])->ip.adj_index[VLIB_TX] = lbi[0];
  
        vnet_buffer (b[1])->ip.adj_index[VLIB_RX] =
  	vnet_buffer (b[1])->ip.adj_index[VLIB_TX];
        vnet_buffer (b[1])->ip.adj_index[VLIB_TX] = lbi[1];
  
        lb[0] = load_balance_get (lbi[0]);
        lb[1] = load_balance_get (lbi[1]);
  
        dpo[0] = load_balance_get_bucket_i (lb[0], 0);
        dpo[1] = load_balance_get_bucket_i (lb[1], 0);
  
        error[0] = ((error[0] == IP4_ERROR_UNKNOWN_PROTOCOL &&
  		   dpo[0]->dpoi_type == DPO_RECEIVE) ?
  		  IP4_ERROR_SPOOFED_LOCAL_PACKETS : error[0]);
        error[0] = ((error[0] == IP4_ERROR_UNKNOWN_PROTOCOL &&
  		   !fib_urpf_check_size (lb[0]->lb_urpf) &&
  		   ip[0]->dst_address.as_u32 != 0xFFFFFFFF)
  		  ? IP4_ERROR_SRC_LOOKUP_MISS : error[0]);
  
        error[1] = ((error[1] == IP4_ERROR_UNKNOWN_PROTOCOL &&
  		   dpo[1]->dpoi_type == DPO_RECEIVE) ?
  		  IP4_ERROR_SPOOFED_LOCAL_PACKETS : error[1]);
        error[1] = ((error[1] == IP4_ERROR_UNKNOWN_PROTOCOL &&
  		   !fib_urpf_check_size (lb[1]->lb_urpf) &&
  		   ip[1]->dst_address.as_u32 != 0xFFFFFFFF)
  		  ? IP4_ERROR_SRC_LOOKUP_MISS : error[1]);
  
        last_check->src.as_u32 = ip[1]->src_address.as_u32;
        last_check->lbi = lbi[1];
        last_check->error = error[1];
      }
    else
      {
        vnet_buffer (b[0])->ip.adj_index[VLIB_RX] =
  	vnet_buffer (b[0])->ip.adj_index[VLIB_TX];
        vnet_buffer (b[0])->ip.adj_index[VLIB_TX] = last_check->lbi;
  
        vnet_buffer (b[1])->ip.adj_index[VLIB_RX] =
  	vnet_buffer (b[1])->ip.adj_index[VLIB_TX];
        vnet_buffer (b[1])->ip.adj_index[VLIB_TX] = last_check->lbi;
  
        error[0] = last_check->error;
        error[1] = last_check->error;
        last_check->first = 0;
      }
  }
  
  enum ip_local_packet_type_e
  {
    IP_LOCAL_PACKET_TYPE_L4,
    IP_LOCAL_PACKET_TYPE_NAT,
    IP_LOCAL_PACKET_TYPE_FRAG,
  };
  
  /**
   * Determine packet type and next node.
   *
   * The expectation is that all packets that are not L4 will skip
   * checksums and source checks.
   */
  always_inline u8
  ip4_local_classify (vlib_buffer_t * b, ip4_header_t * ip, u16 * next)
  {
    ip_lookup_main_t *lm = &ip4_main.lookup_main;
  
    if (PREDICT_FALSE (ip4_is_fragment (ip)))
      {
        *next = IP_LOCAL_NEXT_REASSEMBLY;
        return IP_LOCAL_PACKET_TYPE_FRAG;
      }
    if (PREDICT_FALSE (b->flags & VNET_BUFFER_F_IS_NATED))
      {
        *next = lm->local_next_by_ip_protocol[ip->protocol];
        return IP_LOCAL_PACKET_TYPE_NAT;
      }
  
    *next = lm->local_next_by_ip_protocol[ip->protocol];
    return IP_LOCAL_PACKET_TYPE_L4;
  }
  
  static inline uword
  ip4_local_inline (vlib_main_t * vm,
  		  vlib_node_runtime_t * node,
  		  vlib_frame_t * frame, int head_of_feature_arc)
  {
    u32 *from, n_left_from;
    vlib_node_runtime_t *error_node =
      vlib_node_get_runtime (vm, ip4_input_node.index);
    u16 nexts[VLIB_FRAME_SIZE], *next;
    vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b;
    ip4_header_t *ip[2];
    u8 error[2], pt[2];
  
    ip4_local_last_check_t last_check = {
      /*
       * 0.0.0.0 can appear as the source address of an IP packet,
       * as can any other address, hence the need to use the 'first'
       * member to make sure the .lbi is initialised for the first
       * packet.
       */
      .src = {.as_u32 = 0},
      .lbi = ~0,
      .error = IP4_ERROR_UNKNOWN_PROTOCOL,
      .first = 1,
    };
  
    from = vlib_frame_vector_args (frame);
    n_left_from = frame->n_vectors;
  
    if (node->flags & VLIB_NODE_FLAG_TRACE)
      ip4_forward_next_trace (vm, node, frame, VLIB_TX);
  
    vlib_get_buffers (vm, from, bufs, n_left_from);
    b = bufs;
    next = nexts;
  
    while (n_left_from >= 6)
      {
        u8 not_batch = 0;
  
        /* Prefetch next iteration. */
        {
  	vlib_prefetch_buffer_header (b[4], LOAD);
  	vlib_prefetch_buffer_header (b[5], LOAD);
  
  	CLIB_PREFETCH (b[4]->data, CLIB_CACHE_LINE_BYTES, LOAD);
  	CLIB_PREFETCH (b[5]->data, CLIB_CACHE_LINE_BYTES, LOAD);
        }
  
        error[0] = error[1] = IP4_ERROR_UNKNOWN_PROTOCOL;
  
        ip[0] = vlib_buffer_get_current (b[0]);
        ip[1] = vlib_buffer_get_current (b[1]);
  
        vnet_buffer (b[0])->l3_hdr_offset = b[0]->current_data;
        vnet_buffer (b[1])->l3_hdr_offset = b[1]->current_data;
  
        pt[0] = ip4_local_classify (b[0], ip[0], &next[0]);
        pt[1] = ip4_local_classify (b[1], ip[1], &next[1]);
  
        not_batch = pt[0] ^ pt[1];
  
        if (head_of_feature_arc == 0 || (pt[0] && not_batch == 0))
  	goto skip_checks;
  
        if (PREDICT_TRUE (not_batch == 0))
  	{
  	  ip4_local_check_l4_csum_x2 (vm, b, ip, error);
  	  ip4_local_check_src_x2 (b, ip, &last_check, error);
  	}
        else
  	{
  	  if (!pt[0])
  	    {
  	      ip4_local_check_l4_csum (vm, b[0], ip[0], &error[0]);
  	      ip4_local_check_src (b[0], ip[0], &last_check, &error[0]);
  	    }
  	  if (!pt[1])
  	    {
  	      ip4_local_check_l4_csum (vm, b[1], ip[1], &error[1]);
  	      ip4_local_check_src (b[1], ip[1], &last_check, &error[1]);
  	    }
  	}
  
      skip_checks:
  
        ip4_local_set_next_and_error (error_node, b[0], &next[0], error[0],
  				    head_of_feature_arc);
        ip4_local_set_next_and_error (error_node, b[1], &next[1], error[1],
  				    head_of_feature_arc);
  
        b += 2;
        next += 2;
        n_left_from -= 2;
      }
  
    while (n_left_from > 0)
      {
        error[0] = IP4_ERROR_UNKNOWN_PROTOCOL;
  
        ip[0] = vlib_buffer_get_current (b[0]);
        vnet_buffer (b[0])->l3_hdr_offset = b[0]->current_data;
        pt[0] = ip4_local_classify (b[0], ip[0], &next[0]);
  
        if (head_of_feature_arc == 0 || pt[0])
  	goto skip_check;
  
        ip4_local_check_l4_csum (vm, b[0], ip[0], &error[0]);
        ip4_local_check_src (b[0], ip[0], &last_check, &error[0]);
  
      skip_check:
  
        ip4_local_set_next_and_error (error_node, b[0], &next[0], error[0],
  				    head_of_feature_arc);
  
        b += 1;
        next += 1;
        n_left_from -= 1;
      }
  
    vlib_buffer_enqueue_to_next (vm, node, from, nexts, frame->n_vectors);
    return frame->n_vectors;
  }
  
  VLIB_NODE_FN (ip4_local_node) (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) =
  {
    .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] = "ip4-drop",
      [IP_LOCAL_NEXT_PUNT] = "ip4-punt",
      [IP_LOCAL_NEXT_UDP_LOOKUP] = "ip4-udp-lookup",
      [IP_LOCAL_NEXT_ICMP] = "ip4-icmp-input",
      [IP_LOCAL_NEXT_REASSEMBLY] = "ip4-full-reassembly",
    },
  };
  /* *INDENT-ON* */
  
  
  VLIB_NODE_FN (ip4_local_end_of_arc_node) (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) = {
    .name = "ip4-local-end-of-arc",
    .vector_size = sizeof (u32),
  
    .format_trace = format_ip4_forward_next_trace,
    .sibling_of = "ip4-local",
  };
  
  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* */
  
  #ifndef CLIB_MARCH_VARIANT
  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);
  }
  
  void
  ip4_unregister_protocol (u32 protocol)
  {
    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] = IP_LOCAL_NEXT_PUNT;
  }
  #endif
  
  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)
  	{
  	  u32 node_index = vlib_get_node (vm,
  					  ip4_local_node.index)->
  	    next_nodes[lm->local_next_by_ip_protocol[i]];
  	  vlib_cli_output (vm, "%U: %U", format_ip_protocol, i,
  			   format_vlib_node_name, vm, node_index);
  	}
      }
    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;
    u32 thread_index = vm->thread_index;
    u64 seed;
  
    if (node->flags & VLIB_NODE_FLAG_TRACE)
      ip4_forward_next_trace (vm, node, frame, VLIB_TX);
  
    seed = throttle_seed (&im->arp_throttle, thread_index, vlib_time_now (vm));
  
    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, bi0, adj_index0, sw_if_index0;
  	  ip_adjacency_t *adj0;
  	  vlib_buffer_t *p0, *b0;
  	  ip4_address_t resolve0;
  	  ethernet_arp_header_t *h0;
  	  vnet_hw_interface_t *hw_if0;
  	  u64 r0;
  
  	  pi0 = from[0];
  	  p0 = vlib_get_buffer (vm, pi0);
  
  	  from += 1;
  	  n_left_from -= 1;
  	  to_next_drop[0] = pi0;
  	  to_next_drop += 1;
  	  n_left_to_next_drop -= 1;
  
  	  adj_index0 = vnet_buffer (p0)->ip.adj_index[VLIB_TX];
  	  adj0 = adj_get (adj_index0);
  
  	  if (is_glean)
  	    {
  	      /* resolve the packet's destination */
  	      ip4_header_t *ip0 = vlib_buffer_get_current (p0);
  	      resolve0 = ip0->dst_address;
  	    }
  	  else
  	    {
  	      /* resolve the incomplete adj */
  	      resolve0 = adj0->sub_type.nbr.next_hop.ip4;
  	    }
  
  	  /* combine the address and interface for the hash key */
  	  sw_if_index0 = adj0->rewrite_header.sw_if_index;
  	  r0 = (u64) resolve0.data_u32 << 32;
  	  r0 |= sw_if_index0;
  
  	  if (throttle_check (&im->arp_throttle, thread_index, r0, seed))
  	    {
  	      p0->error = node->errors[IP4_ARP_ERROR_THROTTLED];
  	      continue;
  	    }
  
  	  /*
  	   * 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)
  	    {
  	      p0->error = node->errors[IP4_ARP_ERROR_RESOLVED];
  	      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];
  	      continue;
  	    }
  	  /* Send ARP request. */
  	  h0 =
  	    vlib_packet_template_get_packet (vm,
  					     &im->ip4_arp_request_packet_template,
  					     &bi0);
  	  /* Seems we're out of buffers */
  	  if (PREDICT_FALSE (!h0))
  	    {
  	      p0->error = node->errors[IP4_ARP_ERROR_NO_BUFFERS];
  	      continue;
  	    }
  
  	  b0 = vlib_get_buffer (vm, bi0);
  
  	  /* copy the persistent fields from the original */
  	  clib_memcpy_fast (b0->opaque2, p0->opaque2, sizeof (p0->opaque2));
  
  	  /* 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. */
  	  mac_address_from_bytes (&h0->ip4_over_ethernet[0].mac,
  				  hw_if0->hw_address);
  	  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;
  	    }
  	  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;
  		}
  	    }
  	  h0->ip4_over_ethernet[1].ip4 = resolve0;
  
  	  p0->error = node->errors[IP4_ARP_ERROR_REQUEST_SENT];
  
  	  vlib_buffer_copy_trace_flag (vm, p0, bi0);
  	  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b0);
  	  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;
  }
  
  VLIB_NODE_FN (ip4_arp_node) (vlib_main_t * vm, vlib_node_runtime_t * node,
  			     vlib_frame_t * frame)
  {
    return (ip4_arp_inline (vm, node, frame, 0));
  }
  
  VLIB_NODE_FN (ip4_glean_node) (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_THROTTLED] = "ARP requests throttled",
    [IP4_ARP_ERROR_RESOLVED] = "ARP requests resolved",
    [IP4_ARP_ERROR_NO_BUFFERS] = "ARP requests out of buffer",
    [IP4_ARP_ERROR_REQUEST_SENT] = "ARP requests sent",
    [IP4_ARP_ERROR_NON_ARP_ADJ] = "ARPs to non-ARP adjacencies",
    [IP4_ARP_ERROR_NO_SOURCE_ADDRESS] = "no source address for ARP request",
  };
  
  /* *INDENT-OFF* */
  VLIB_REGISTER_NODE (ip4_arp_node) =
  {
    .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) =
  {
    .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",
    },
  };
  /* *INDENT-ON* */
  
  #define foreach_notrace_ip4_arp_error           \
  _(THROTTLED)                                    \
  _(RESOLVED)                                     \
  _(NO_BUFFERS)                                   \
  _(REQUEST_SENT)                                 \
  _(NON_ARP_ADJ)                                  \
  _(NO_SOURCE_ADDRESS)
  
  static 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);
  
  
  #ifndef CLIB_MARCH_VARIANT
  /* 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,
  		    u8 refresh)
  {
    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;
    adj_index_t ai;
    u32 bi = 0;
    u8 unicast_rewrite = 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);
      }
  
    h = vlib_packet_template_get_packet (vm,
  				       &im->ip4_arp_request_packet_template,
  				       &bi);
  
    if (!h)
      return clib_error_return (0, "ARP request packet allocation failed");
  
    hi = vnet_get_sup_hw_interface (vnm, sw_if_index);
    if (PREDICT_FALSE (!hi->hw_address))
      {
        return clib_error_return (0, "%U: interface %U do not support ip probe",
  				format_ip4_address, dst,
  				format_vnet_sw_if_index_name, vnm,
  				sw_if_index);
      }
  
    mac_address_from_bytes (&h->ip4_over_ethernet[0].mac, hi->hw_address);
  
    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;
  
    ip46_address_t nh = {
      .ip4 = *dst,
    };
  
    ai = adj_nbr_add_or_lock (FIB_PROTOCOL_IP4,
  			    VNET_LINK_IP4, &nh, sw_if_index);
    adj = adj_get (ai);
  
    /* Peer has been previously resolved, retrieve glean adj instead */
    if (adj->lookup_next_index == IP_LOOKUP_NEXT_REWRITE)
      {
        if (refresh)
  	unicast_rewrite = 1;
        else
  	{
  	  adj_unlock (ai);
  	  ai = adj_glean_add_or_lock (FIB_PROTOCOL_IP4,
  				      VNET_LINK_IP4, sw_if_index, &nh);
  	  adj = adj_get (ai);
  	}
      }
  
    /* Add encapsulation string for software interface (e.g. ethernet header). */
    vnet_rewrite_one_header (adj[0], h, sizeof (ethernet_header_t));
    if (unicast_rewrite)
      {
        u16 *etype = vlib_buffer_get_current (b) - 2;
        etype[0] = clib_host_to_net_u16 (ETHERNET_TYPE_ARP);
      }
    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);
    }
  
    adj_unlock (ai);
    return /* no error */ 0;
  }
  #endif
  
  typedef enum
  {
    IP4_REWRITE_NEXT_DROP,
    IP4_REWRITE_NEXT_ICMP_ERROR,
    IP4_REWRITE_NEXT_FRAGMENT,
    IP4_REWRITE_N_NEXT		/* Last */
  } ip4_rewrite_next_t;
  
  /**
   * This bits of an IPv4 address to mask to construct a multicast
   * MAC address
   */
  #if CLIB_ARCH_IS_BIG_ENDIAN
  #define IP4_MCAST_ADDR_MASK 0x007fffff
  #else
  #define IP4_MCAST_ADDR_MASK 0xffff7f00
  #endif
  
  always_inline void
  ip4_mtu_check (vlib_buffer_t * b, u16 packet_len,
  	       u16 adj_packet_bytes, bool df, u16 * next,
  	       u8 is_midchain, u32 * error)
  {
    if (packet_len > adj_packet_bytes)
      {
        *error = IP4_ERROR_MTU_EXCEEDED;
        if (df)
  	{
  	  icmp4_error_set_vnet_buffer
  	    (b, ICMP4_destination_unreachable,
  	     ICMP4_destination_unreachable_fragmentation_needed_and_dont_fragment_set,
  	     adj_packet_bytes);
  	  *next = IP4_REWRITE_NEXT_ICMP_ERROR;
  	}
        else
  	{
  	  /* IP fragmentation */
  	  ip_frag_set_vnet_buffer (b, adj_packet_bytes,
  				   (is_midchain ?
  				    IP_FRAG_NEXT_IP_REWRITE_MIDCHAIN :
  				    IP_FRAG_NEXT_IP_REWRITE), 0);
  	  *next = IP4_REWRITE_NEXT_FRAGMENT;
  	}
      }
  }
  
  /* increment TTL & update checksum.
     Works either endian, so no need for byte swap. */
  static_always_inline void
  ip4_ttl_inc (vlib_buffer_t * b, ip4_header_t * ip)
  {
    i32 ttl;
    u32 checksum;
    if (PREDICT_FALSE (b->flags & VNET_BUFFER_F_LOCALLY_ORIGINATED))
      {
        b->flags &= ~VNET_BUFFER_F_LOCALLY_ORIGINATED;
        return;
      }
  
    ttl = ip->ttl;
  
    checksum = ip->checksum - clib_host_to_net_u16 (0x0100);
    checksum += checksum >= 0xffff;
  
    ip->checksum = checksum;
    ttl += 1;
    ip->ttl = ttl;
  
    ASSERT (ip->checksum == ip4_header_checksum (ip));
  }
  
  /* Decrement TTL & update checksum.
     Works either endian, so no need for byte swap. */
  static_always_inline void
  ip4_ttl_and_checksum_check (vlib_buffer_t * b, ip4_header_t * ip, u16 * next,
  			    u32 * error)
  {
    i32 ttl;
    u32 checksum;
    if (PREDICT_FALSE (b->flags & VNET_BUFFER_F_LOCALLY_ORIGINATED))
      {
        b->flags &= ~VNET_BUFFER_F_LOCALLY_ORIGINATED;
        return;
      }
  
    ttl = ip->ttl;
  
    /* Input node should have reject packets with ttl 0. */
    ASSERT (ip->ttl > 0);
  
    checksum = ip->checksum + clib_host_to_net_u16 (0x0100);
    checksum += checksum >= 0xffff;
  
    ip->checksum = checksum;
    ttl -= 1;
    ip->ttl = ttl;
  
    /*
     * If the ttl drops below 1 when forwarding, generate
     * an ICMP response.
     */
    if (PREDICT_FALSE (ttl <= 0))
      {
        *error = IP4_ERROR_TIME_EXPIRED;
        vnet_buffer (b)->sw_if_index[VLIB_TX] = (u32) ~ 0;
        icmp4_error_set_vnet_buffer (b, ICMP4_time_exceeded,
  				   ICMP4_time_exceeded_ttl_exceeded_in_transit,
  				   0);
        *next = IP4_REWRITE_NEXT_ICMP_ERROR;
      }
  
    /* Verify checksum. */
    ASSERT ((ip->checksum == ip4_header_checksum (ip)) ||
  	  (b->flags & VNET_BUFFER_F_OFFLOAD_IP_CKSUM));
  }
  
  
  always_inline uword
  ip4_rewrite_inline_with_gso (vlib_main_t * vm,
  			     vlib_node_runtime_t * node,
  			     vlib_frame_t * frame,
  			     int do_counters, int is_midchain, int is_mcast,
  			     int do_gso)
  {
    ip_lookup_main_t *lm = &ip4_main.lookup_main;
    u32 *from = vlib_frame_vector_args (frame);
    vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b;
    u16 nexts[VLIB_FRAME_SIZE], *next;
    u32 n_left_from;
    vlib_node_runtime_t *error_node =
      vlib_node_get_runtime (vm, ip4_input_node.index);
  
    n_left_from = frame->n_vectors;
    u32 thread_index = vm->thread_index;
  
    vlib_get_buffers (vm, from, bufs, n_left_from);
    clib_memset_u16 (nexts, IP4_REWRITE_NEXT_DROP, n_left_from);
  
  #if (CLIB_N_PREFETCHES >= 8)
    if (n_left_from >= 6)
      {
        int i;
        for (i = 2; i < 6; i++)
  	vlib_prefetch_buffer_header (bufs[i], LOAD);
      }
  
    next = nexts;
    b = bufs;
    while (n_left_from >= 8)
      {
        ip_adjacency_t *adj0, *adj1;
        ip4_header_t *ip0, *ip1;
        u32 rw_len0, error0, adj_index0;
        u32 rw_len1, error1, adj_index1;
        u32 tx_sw_if_index0, tx_sw_if_index1;
        u8 *p;
  
        vlib_prefetch_buffer_header (b[6], LOAD);
        vlib_prefetch_buffer_header (b[7], LOAD);
  
        adj_index0 = vnet_buffer (b[0])->ip.adj_index[VLIB_TX];
        adj_index1 = vnet_buffer (b[1])->ip.adj_index[VLIB_TX];
  
        /*
         * pre-fetch the per-adjacency counters
         */
        if (do_counters)
  	{
  	  vlib_prefetch_combined_counter (&adjacency_counters,
  					  thread_index, adj_index0);
  	  vlib_prefetch_combined_counter (&adjacency_counters,
  					  thread_index, adj_index1);
  	}
  
        ip0 = vlib_buffer_get_current (b[0]);
        ip1 = vlib_buffer_get_current (b[1]);
  
        error0 = error1 = IP4_ERROR_NONE;
  
        ip4_ttl_and_checksum_check (b[0], ip0, next + 0, &error0);
        ip4_ttl_and_checksum_check (b[1], ip1, next + 1, &error1);
  
        /* Rewrite packet header and updates lengths. */
        adj0 = adj_get (adj_index0);
        adj1 = adj_get (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 (b[0])->ip.save_rewrite_length = rw_len0;
        vnet_buffer (b[1])->ip.save_rewrite_length = rw_len1;
  
        p = vlib_buffer_get_current (b[2]);
        CLIB_PREFETCH (p - CLIB_CACHE_LINE_BYTES, CLIB_CACHE_LINE_BYTES, STORE);
        CLIB_PREFETCH (p, CLIB_CACHE_LINE_BYTES, LOAD);
  
        p = vlib_buffer_get_current (b[3]);
        CLIB_PREFETCH (p - CLIB_CACHE_LINE_BYTES, CLIB_CACHE_LINE_BYTES, STORE);
        CLIB_PREFETCH (p, CLIB_CACHE_LINE_BYTES, LOAD);
  
        /* Check MTU of outgoing interface. */
        u16 ip0_len = clib_net_to_host_u16 (ip0->length);
        u16 ip1_len = clib_net_to_host_u16 (ip1->length);
  
        if (do_gso && (b[0]->flags & VNET_BUFFER_F_GSO))
  	ip0_len = gso_mtu_sz (b[0]);
        if (do_gso && (b[1]->flags & VNET_BUFFER_F_GSO))
  	ip1_len = gso_mtu_sz (b[1]);
  
        ip4_mtu_check (b[0], ip0_len,
  		     adj0[0].rewrite_header.max_l3_packet_bytes,
  		     ip0->flags_and_fragment_offset &
  		     clib_host_to_net_u16 (IP4_HEADER_FLAG_DONT_FRAGMENT),
  		     next + 0, is_midchain, &error0);
        ip4_mtu_check (b[1], ip1_len,
  		     adj1[0].rewrite_header.max_l3_packet_bytes,
  		     ip1->flags_and_fragment_offset &
  		     clib_host_to_net_u16 (IP4_HEADER_FLAG_DONT_FRAGMENT),
  		     next + 1, is_midchain, &error1);
  
        if (is_mcast)
  	{
  	  error0 = ((adj0[0].rewrite_header.sw_if_index ==
  		     vnet_buffer (b[0])->sw_if_index[VLIB_RX]) ?
  		    IP4_ERROR_SAME_INTERFACE : error0);
  	  error1 = ((adj1[0].rewrite_header.sw_if_index ==
  		     vnet_buffer (b[1])->sw_if_index[VLIB_RX]) ?
  		    IP4_ERROR_SAME_INTERFACE : error1);
  	}
  
        /* Don't adjust the buffer for ttl issue; icmp-error node wants
         * to see the IP header */
        if (PREDICT_TRUE (error0 == IP4_ERROR_NONE))
  	{
  	  u32 next_index = adj0[0].rewrite_header.next_index;
  	  vlib_buffer_advance (b[0], -(word) rw_len0);
  
  	  tx_sw_if_index0 = adj0[0].rewrite_header.sw_if_index;
  	  vnet_buffer (b[0])->sw_if_index[VLIB_TX] = tx_sw_if_index0;
  
  	  if (PREDICT_FALSE
  	      (adj0[0].rewrite_header.flags & VNET_REWRITE_HAS_FEATURES))
  	    vnet_feature_arc_start (lm->output_feature_arc_index,
  				    tx_sw_if_index0, &next_index, b[0]);
  	  next[0] = next_index;
  	  if (is_midchain)
  	    calc_checksums (vm, b[0]);
  	}
        else
  	{
  	  b[0]->error = error_node->errors[error0];
  	  if (error0 == IP4_ERROR_MTU_EXCEEDED)
  	    ip4_ttl_inc (b[0], ip0);
  	}
        if (PREDICT_TRUE (error1 == IP4_ERROR_NONE))
  	{
  	  u32 next_index = adj1[0].rewrite_header.next_index;
  	  vlib_buffer_advance (b[1], -(word) rw_len1);
  
  	  tx_sw_if_index1 = adj1[0].rewrite_header.sw_if_index;
  	  vnet_buffer (b[1])->sw_if_index[VLIB_TX] = tx_sw_if_index1;
  
  	  if (PREDICT_FALSE
  	      (adj1[0].rewrite_header.flags & VNET_REWRITE_HAS_FEATURES))
  	    vnet_feature_arc_start (lm->output_feature_arc_index,
  				    tx_sw_if_index1, &next_index, b[1]);
  	  next[1] = next_index;
  	  if (is_midchain)
  	    calc_checksums (vm, b[1]);
  	}
        else
  	{
  	  b[1]->error = error_node->errors[error1];
  	  if (error1 == IP4_ERROR_MTU_EXCEEDED)
  	    ip4_ttl_inc (b[1], ip1);
  	}
  
        /* Guess we are only writing on simple Ethernet header. */
        vnet_rewrite_two_headers (adj0[0], adj1[0],
  				ip0, ip1, sizeof (ethernet_header_t));
  
        if (do_counters)
  	{
  	  if (error0 == IP4_ERROR_NONE)
  	    vlib_increment_combined_counter
  	      (&adjacency_counters,
  	       thread_index,
  	       adj_index0, 1,
  	       vlib_buffer_length_in_chain (vm, b[0]) + rw_len0);
  
  	  if (error1 == IP4_ERROR_NONE)
  	    vlib_increment_combined_counter
  	      (&adjacency_counters,
  	       thread_index,
  	       adj_index1, 1,
  	       vlib_buffer_length_in_chain (vm, b[1]) + rw_len1);
  	}
  
        if (is_midchain)
  	{
  	  if (error0 == IP4_ERROR_NONE && adj0->sub_type.midchain.fixup_func)
  	    adj0->sub_type.midchain.fixup_func
  	      (vm, adj0, b[0], adj0->sub_type.midchain.fixup_data);
  	  if (error1 == IP4_ERROR_NONE && adj1->sub_type.midchain.fixup_func)
  	    adj1->sub_type.midchain.fixup_func
  	      (vm, adj1, b[1], adj1->sub_type.midchain.fixup_data);
  	}
  
        if (is_mcast)
  	{
  	  /* copy bytes from the IP address into the MAC rewrite */
  	  if (error0 == IP4_ERROR_NONE)
  	    vnet_ip_mcast_fixup_header (IP4_MCAST_ADDR_MASK,
  					adj0->rewrite_header.dst_mcast_offset,
  					&ip0->dst_address.as_u32, (u8 *) ip0);
  	  if (error1 == IP4_ERROR_NONE)
  	    vnet_ip_mcast_fixup_header (IP4_MCAST_ADDR_MASK,
  					adj1->rewrite_header.dst_mcast_offset,
  					&ip1->dst_address.as_u32, (u8 *) ip1);
  	}
  
        next += 2;
        b += 2;
        n_left_from -= 2;
      }
  #elif (CLIB_N_PREFETCHES >= 4)
    next = nexts;
    b = bufs;
    while (n_left_from >= 1)
      {
        ip_adjacency_t *adj0;
        ip4_header_t *ip0;
        u32 rw_len0, error0, adj_index0;
        u32 tx_sw_if_index0;
        u8 *p;
  
        /* Prefetch next iteration */
        if (PREDICT_TRUE (n_left_from >= 4))
  	{
  	  ip_adjacency_t *adj2;
  	  u32 adj_index2;
  
  	  vlib_prefetch_buffer_header (b[3], LOAD);
  	  vlib_prefetch_buffer_data (b[2], LOAD);
  
  	  /* Prefetch adj->rewrite_header */
  	  adj_index2 = vnet_buffer (b[2])->ip.adj_index[VLIB_TX];
  	  adj2 = adj_get (adj_index2);
  	  p = (u8 *) adj2;
  	  CLIB_PREFETCH (p + CLIB_CACHE_LINE_BYTES, CLIB_CACHE_LINE_BYTES,
  			 LOAD);
  	}
  
        adj_index0 = vnet_buffer (b[0])->ip.adj_index[VLIB_TX];
  
        /*
         * Prefetch the per-adjacency counters
         */
        if (do_counters)
  	{
  	  vlib_prefetch_combined_counter (&adjacency_counters,
  					  thread_index, adj_index0);
  	}
  
        ip0 = vlib_buffer_get_current (b[0]);
  
        error0 = IP4_ERROR_NONE;
  
        ip4_ttl_and_checksum_check (b[0], ip0, next + 0, &error0);
  
        /* Rewrite packet header and updates lengths. */
        adj0 = adj_get (adj_index0);
  
        /* Rewrite header was prefetched. */
        rw_len0 = adj0[0].rewrite_header.data_bytes;
        vnet_buffer (b[0])->ip.save_rewrite_length = rw_len0;
  
        /* Check MTU of outgoing interface. */
        u16 ip0_len = clib_net_to_host_u16 (ip0->length);
  
        if (do_gso && (b[0]->flags & VNET_BUFFER_F_GSO))
  	ip0_len = gso_mtu_sz (b[0]);
  
        ip4_mtu_check (b[0], ip0_len,
  		     adj0[0].rewrite_header.max_l3_packet_bytes,
  		     ip0->flags_and_fragment_offset &
  		     clib_host_to_net_u16 (IP4_HEADER_FLAG_DONT_FRAGMENT),
  		     next + 0, is_midchain, &error0);
  
        if (is_mcast)
  	{
  	  error0 = ((adj0[0].rewrite_header.sw_if_index ==
  		     vnet_buffer (b[0])->sw_if_index[VLIB_RX]) ?
  		    IP4_ERROR_SAME_INTERFACE : error0);
  	}
  
        /* Don't adjust the buffer for ttl issue; icmp-error node wants
         * to see the IP header */
        if (PREDICT_TRUE (error0 == IP4_ERROR_NONE))
  	{
  	  u32 next_index = adj0[0].rewrite_header.next_index;
  	  vlib_buffer_advance (b[0], -(word) rw_len0);
  	  tx_sw_if_index0 = adj0[0].rewrite_header.sw_if_index;
  	  vnet_buffer (b[0])->sw_if_index[VLIB_TX] = tx_sw_if_index0;
  
  	  if (PREDICT_FALSE
  	      (adj0[0].rewrite_header.flags & VNET_REWRITE_HAS_FEATURES))
  	    vnet_feature_arc_start (lm->output_feature_arc_index,
  				    tx_sw_if_index0, &next_index, b[0]);
  	  next[0] = next_index;
  
  	  if (is_midchain)
  	    calc_checksums (vm, b[0]);
  
  	  /* Guess we are only writing on simple Ethernet header. */
  	  vnet_rewrite_one_header (adj0[0], ip0, sizeof (ethernet_header_t));
  
  	  /*
  	   * Bump the per-adjacency counters
  	   */
  	  if (do_counters)
  	    vlib_increment_combined_counter
  	      (&adjacency_counters,
  	       thread_index,
  	       adj_index0, 1, vlib_buffer_length_in_chain (vm,
  							   b[0]) + rw_len0);
  
  	  if (is_midchain && adj0->sub_type.midchain.fixup_func)
  	    adj0->sub_type.midchain.fixup_func
  	      (vm, adj0, b[0], adj0->sub_type.midchain.fixup_data);
  
  	  if (is_mcast)
  	    /* copy bytes from the IP address into the MAC rewrite */
  	    vnet_ip_mcast_fixup_header (IP4_MCAST_ADDR_MASK,
  					adj0->rewrite_header.dst_mcast_offset,
  					&ip0->dst_address.as_u32, (u8 *) ip0);
  	}
        else
  	{
  	  b[0]->error = error_node->errors[error0];
  	  if (error0 == IP4_ERROR_MTU_EXCEEDED)
  	    ip4_ttl_inc (b[0], ip0);
  	}
  
        next += 1;
        b += 1;
        n_left_from -= 1;
      }
  #endif
  
    while (n_left_from > 0)
      {
        ip_adjacency_t *adj0;
        ip4_header_t *ip0;
        u32 rw_len0, adj_index0, error0;
        u32 tx_sw_if_index0;
  
        adj_index0 = vnet_buffer (b[0])->ip.adj_index[VLIB_TX];
  
        adj0 = adj_get (adj_index0);
  
        if (do_counters)
  	vlib_prefetch_combined_counter (&adjacency_counters,
  					thread_index, adj_index0);
  
        ip0 = vlib_buffer_get_current (b[0]);
  
        error0 = IP4_ERROR_NONE;
  
        ip4_ttl_and_checksum_check (b[0], ip0, next + 0, &error0);
  
  
        /* Update packet buffer attributes/set output interface. */
        rw_len0 = adj0[0].rewrite_header.data_bytes;
        vnet_buffer (b[0])->ip.save_rewrite_length = rw_len0;
  
        /* Check MTU of outgoing interface. */
        u16 ip0_len = clib_net_to_host_u16 (ip0->length);
        if (do_gso && (b[0]->flags & VNET_BUFFER_F_GSO))
  	ip0_len = gso_mtu_sz (b[0]);
  
        ip4_mtu_check (b[0], ip0_len,
  		     adj0[0].rewrite_header.max_l3_packet_bytes,
  		     ip0->flags_and_fragment_offset &
  		     clib_host_to_net_u16 (IP4_HEADER_FLAG_DONT_FRAGMENT),
  		     next + 0, is_midchain, &error0);
  
        if (is_mcast)
  	{
  	  error0 = ((adj0[0].rewrite_header.sw_if_index ==
  		     vnet_buffer (b[0])->sw_if_index[VLIB_RX]) ?
  		    IP4_ERROR_SAME_INTERFACE : error0);
  	}
  
        /* Don't adjust the buffer for ttl issue; icmp-error node wants
         * to see the IP header */
        if (PREDICT_TRUE (error0 == IP4_ERROR_NONE))
  	{
  	  u32 next_index = adj0[0].rewrite_header.next_index;
  	  vlib_buffer_advance (b[0], -(word) rw_len0);
  	  tx_sw_if_index0 = adj0[0].rewrite_header.sw_if_index;
  	  vnet_buffer (b[0])->sw_if_index[VLIB_TX] = tx_sw_if_index0;
  
  	  if (PREDICT_FALSE
  	      (adj0[0].rewrite_header.flags & VNET_REWRITE_HAS_FEATURES))
  	    vnet_feature_arc_start (lm->output_feature_arc_index,
  				    tx_sw_if_index0, &next_index, b[0]);
  	  next[0] = next_index;
  
  	  if (is_midchain)
  	    /* this acts on the packet that is about to be encapped */
  	    calc_checksums (vm, b[0]);
  
  	  /* Guess we are only writing on simple Ethernet header. */
  	  vnet_rewrite_one_header (adj0[0], ip0, sizeof (ethernet_header_t));
  
  	  if (do_counters)
  	    vlib_increment_combined_counter
  	      (&adjacency_counters,
  	       thread_index, adj_index0, 1,
  	       vlib_buffer_length_in_chain (vm, b[0]) + rw_len0);
  
  	  if (is_midchain && adj0->sub_type.midchain.fixup_func)
  	    adj0->sub_type.midchain.fixup_func
  	      (vm, adj0, b[0], adj0->sub_type.midchain.fixup_data);
  
  	  if (is_mcast)
  	    /* copy bytes from the IP address into the MAC rewrite */
  	    vnet_ip_mcast_fixup_header (IP4_MCAST_ADDR_MASK,
  					adj0->rewrite_header.dst_mcast_offset,
  					&ip0->dst_address.as_u32, (u8 *) ip0);
  	}
        else
  	{
  	  b[0]->error = error_node->errors[error0];
  	  /* undo the TTL decrement - we'll be back to do it again */
  	  if (error0 == IP4_ERROR_MTU_EXCEEDED)
  	    ip4_ttl_inc (b[0], ip0);
  	}
  
        next += 1;
        b += 1;
        n_left_from -= 1;
      }
  
  
    /* 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);
  
    vlib_buffer_enqueue_to_next (vm, node, from, nexts, frame->n_vectors);
    return frame->n_vectors;
  }
  
  always_inline uword
  ip4_rewrite_inline (vlib_main_t * vm,
  		    vlib_node_runtime_t * node,
  		    vlib_frame_t * frame,
  		    int do_counters, int is_midchain, int is_mcast)
  {
    vnet_main_t *vnm = vnet_get_main ();
    if (PREDICT_FALSE (vnm->interface_main.gso_interface_count > 0))
      return ip4_rewrite_inline_with_gso (vm, node, frame, do_counters,
  					is_midchain, is_mcast,
  					1 /* do_gso */ );
    else
      return ip4_rewrite_inline_with_gso (vm, node, frame, do_counters,
  					is_midchain, is_mcast,
  					0 /* no do_gso */ );
  }
  
  
  /** @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 ip4-drop
  */
  
  VLIB_NODE_FN (ip4_rewrite_node) (vlib_main_t * vm, vlib_node_runtime_t * node,
  				 vlib_frame_t * frame)
  {
    if (adj_are_counters_enabled ())
      return ip4_rewrite_inline (vm, node, frame, 1, 0, 0);
    else
      return ip4_rewrite_inline (vm, node, frame, 0, 0, 0);
  }
  
  VLIB_NODE_FN (ip4_rewrite_bcast_node) (vlib_main_t * vm,
  				       vlib_node_runtime_t * node,
  				       vlib_frame_t * frame)
  {
    if (adj_are_counters_enabled ())
      return ip4_rewrite_inline (vm, node, frame, 1, 0, 0);
    else
      return ip4_rewrite_inline (vm, node, frame, 0, 0, 0);
  }
  
  VLIB_NODE_FN (ip4_midchain_node) (vlib_main_t * vm,
  				  vlib_node_runtime_t * node,
  				  vlib_frame_t * frame)
  {
    if (adj_are_counters_enabled ())
      return ip4_rewrite_inline (vm, node, frame, 1, 1, 0);
    else
      return ip4_rewrite_inline (vm, node, frame, 0, 1, 0);
  }
  
  VLIB_NODE_FN (ip4_rewrite_mcast_node) (vlib_main_t * vm,
  				       vlib_node_runtime_t * node,
  				       vlib_frame_t * frame)
  {
    if (adj_are_counters_enabled ())
      return ip4_rewrite_inline (vm, node, frame, 1, 0, 1);
    else
      return ip4_rewrite_inline (vm, node, frame, 0, 0, 1);
  }
  
  VLIB_NODE_FN (ip4_mcast_midchain_node) (vlib_main_t * vm,
  					vlib_node_runtime_t * node,
  					vlib_frame_t * frame)
  {
    if (adj_are_counters_enabled ())
      return ip4_rewrite_inline (vm, node, frame, 1, 1, 1);
    else
      return ip4_rewrite_inline (vm, node, frame, 0, 1, 1);
  }
  
  /* *INDENT-OFF* */
  VLIB_REGISTER_NODE (ip4_rewrite_node) = {
    .name = "ip4-rewrite",
    .vector_size = sizeof (u32),
  
    .format_trace = format_ip4_rewrite_trace,
  
    .n_next_nodes = IP4_REWRITE_N_NEXT,
    .next_nodes = {
      [IP4_REWRITE_NEXT_DROP] = "ip4-drop",
      [IP4_REWRITE_NEXT_ICMP_ERROR] = "ip4-icmp-error",
      [IP4_REWRITE_NEXT_FRAGMENT] = "ip4-frag",
    },
  };
  
  VLIB_REGISTER_NODE (ip4_rewrite_bcast_node) = {
    .name = "ip4-rewrite-bcast",
    .vector_size = sizeof (u32),
  
    .format_trace = format_ip4_rewrite_trace,
    .sibling_of = "ip4-rewrite",
  };
  
  VLIB_REGISTER_NODE (ip4_rewrite_mcast_node) = {
    .name = "ip4-rewrite-mcast",
    .vector_size = sizeof (u32),
  
    .format_trace = format_ip4_rewrite_trace,
    .sibling_of = "ip4-rewrite",
  };
  
  VLIB_REGISTER_NODE (ip4_mcast_midchain_node) = {
    .name = "ip4-mcast-midchain",
    .vector_size = sizeof (u32),
  
    .format_trace = format_ip4_rewrite_trace,
    .sibling_of = "ip4-rewrite",
  };
  
  VLIB_REGISTER_NODE (ip4_midchain_node) = {
    .name = "ip4-midchain",
    .vector_size = sizeof (u32),
    .format_trace = format_ip4_rewrite_trace,
    .sibling_of = "ip4-rewrite",
  };
  /* *INDENT-ON */
  
  static 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_lookup_step_one (mtrie0, a);
    leaf0 = ip4_fib_mtrie_lookup_step (mtrie0, leaf0, a, 2);
    leaf0 = ip4_fib_mtrie_lookup_step (mtrie0, leaf0, a, 3);
  
    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* */
  
  #ifndef CLIB_MARCH_VARIANT
  int
  vnet_set_ip4_flow_hash (u32 table_id, u32 flow_hash_config)
  {
    u32 fib_index;
  
    fib_index = fib_table_find (FIB_PROTOCOL_IP4, table_id);
  
    if (~0 == fib_index)
      return VNET_API_ERROR_NO_SUCH_FIB;
  
    fib_table_set_flow_hash_config (fib_index, FIB_PROTOCOL_IP4,
  				  flow_hash_config);
  
    return 0;
  }
  #endif
  
  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* */
  
  #ifndef CLIB_MARCH_VARIANT
  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;
  }
  #endif
  
  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* */
  
  static clib_error_t *
  ip4_config (vlib_main_t * vm, unformat_input_t * input)
  {
    ip4_main_t *im = &ip4_main;
    uword heapsize = 0;
  
    while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
      {
        if (unformat (input, "heap-size %U", unformat_memory_size, &heapsize))
  	;
        else
  	return clib_error_return (0,
  				  "invalid heap-size parameter `%U'",
  				  format_unformat_error, input);
      }
  
    im->mtrie_heap_size = heapsize;
  
    return 0;
  }
  
  VLIB_EARLY_CONFIG_FUNCTION (ip4_config, "ip");
  
  /*
   * fd.io coding-style-patch-verification: ON
   *
   * Local Variables:
   * eval: (c-set-style "gnu")
   * End:
   */
  