lookup.c

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/*
 * 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/ip_lookup.c: ip4/6 adjacency and lookup table managment
 *
 * 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/ip/ip.h>
#include <vnet/adj/adj.h>
#include <vnet/fib/fib_table.h>
#include <vnet/fib/ip4_fib.h>
#include <vnet/fib/ip6_fib.h>
#include <vnet/mpls/mpls.h>
#include <vnet/dpo/drop_dpo.h>
#include <vnet/dpo/classify_dpo.h>
#include <vnet/dpo/punt_dpo.h>
#include <vnet/dpo/receive_dpo.h>
#include <vnet/dpo/ip_null_dpo.h>

/**
 * @file
 * @brief IPv4 and IPv6 adjacency and lookup table managment.
 *
 */

clib_error_t *
ip_interface_address_add_del (ip_lookup_main_t * lm,
                              u32 sw_if_index,
                              void * addr_fib,
                              u32 address_length,
                              u32 is_del,
                              u32 * result_if_address_index)
{
  vnet_main_t * vnm = vnet_get_main();
  ip_interface_address_t * a, * prev, * next;
  uword * p = mhash_get (&lm->address_to_if_address_index, addr_fib);

  vec_validate_init_empty (lm->if_address_pool_index_by_sw_if_index, sw_if_index, ~0);
  a = p ? pool_elt_at_index (lm->if_address_pool, p[0]) : 0;

  /* Verify given length. */
  if ((a && (address_length != a->address_length)) || (address_length == 0))
    {
      vnm->api_errno = VNET_API_ERROR_ADDRESS_LENGTH_MISMATCH;
      return clib_error_create 
        ( "%U wrong length (expected %d) for interface %U",
          lm->format_address_and_length, addr_fib,
          address_length, a? a->address_length : -1,
          format_vnet_sw_if_index_name, vnm, sw_if_index);
    }

  if (is_del)
    {
      if (!a) 
        {
          vnet_sw_interface_t * si = vnet_get_sw_interface (vnm, sw_if_index);
          vnm->api_errno = VNET_API_ERROR_ADDRESS_NOT_FOUND_FOR_INTERFACE;
          return clib_error_create ("%U not found for interface %U",
                                    lm->format_address_and_length, 
                                    addr_fib, address_length,
                                    format_vnet_sw_interface_name, vnm, si);
        }

      if (a->prev_this_sw_interface != ~0)
        {
          prev = pool_elt_at_index (lm->if_address_pool, a->prev_this_sw_interface);
          prev->next_this_sw_interface = a->next_this_sw_interface;
        }
      if (a->next_this_sw_interface != ~0)
        {
          next = pool_elt_at_index (lm->if_address_pool, a->next_this_sw_interface);
          next->prev_this_sw_interface = a->prev_this_sw_interface;

          if(a->prev_this_sw_interface == ~0)
                 lm->if_address_pool_index_by_sw_if_index[sw_if_index]  = a->next_this_sw_interface;
        }

      if ((a->next_this_sw_interface  == ~0) &&  (a->prev_this_sw_interface == ~0))
        lm->if_address_pool_index_by_sw_if_index[sw_if_index] = ~0;

      mhash_unset (&lm->address_to_if_address_index, addr_fib,
                   /* old_value */ 0);
      pool_put (lm->if_address_pool, a);

      if (result_if_address_index)
        *result_if_address_index = ~0;
    }

  else if (! a)
    {
      u32 pi; /* previous index */
      u32 ai; 
      u32 hi; /* head index */

      pool_get (lm->if_address_pool, a);
      memset (a, ~0, sizeof (a[0]));
      ai = a - lm->if_address_pool;

      hi = pi = lm->if_address_pool_index_by_sw_if_index[sw_if_index];
      prev = 0;
      while (pi != (u32)~0)
        {
          prev = pool_elt_at_index(lm->if_address_pool, pi);
          pi = prev->next_this_sw_interface;
        }
      pi = prev ? prev - lm->if_address_pool : (u32)~0;

      a->address_key = mhash_set (&lm->address_to_if_address_index,
                                  addr_fib, ai, /* old_value */ 0);
      a->address_length = address_length;
      a->sw_if_index = sw_if_index;
      a->flags = 0;
      a->prev_this_sw_interface = pi;
      a->next_this_sw_interface = ~0;
      if (prev)
          prev->next_this_sw_interface = ai;

      lm->if_address_pool_index_by_sw_if_index[sw_if_index] = 
        (hi != ~0) ? hi : ai;
      if (result_if_address_index)
        *result_if_address_index = ai;
    }
  else
    {
      if (result_if_address_index)
        *result_if_address_index = a - lm->if_address_pool;
    }
    

  return /* no error */ 0;
}

void ip_lookup_init (ip_lookup_main_t * lm, u32 is_ip6)
{
  /* ensure that adjacency is cacheline aligned and sized */
  STATIC_ASSERT(STRUCT_OFFSET_OF(ip_adjacency_t, cacheline0) == 0,
                "Cache line marker must be 1st element in struct");
  STATIC_ASSERT(STRUCT_OFFSET_OF(ip_adjacency_t, cacheline1) == CLIB_CACHE_LINE_BYTES,
                "Data in cache line 0 is bigger than cache line size");

  /* Preallocate three "special" adjacencies */
  lm->adjacency_heap = adj_pool;

  if (! lm->fib_result_n_bytes)
    lm->fib_result_n_bytes = sizeof (uword);

  lm->is_ip6 = is_ip6;
  if (is_ip6)
    {
      lm->format_address_and_length = format_ip6_address_and_length;
      mhash_init (&lm->address_to_if_address_index, sizeof (uword),
                  sizeof (ip6_address_fib_t));
    }
  else
    {
      lm->format_address_and_length = format_ip4_address_and_length;
      mhash_init (&lm->address_to_if_address_index, sizeof (uword),
                  sizeof (ip4_address_fib_t));
    }

  {
    int i;

    /* Setup all IP protocols to be punted and builtin-unknown. */
    for (i = 0; i < 256; i++)
      {
        lm->local_next_by_ip_protocol[i] = IP_LOCAL_NEXT_PUNT;
        lm->builtin_protocol_by_ip_protocol[i] = IP_BUILTIN_PROTOCOL_UNKNOWN;
      }

    lm->local_next_by_ip_protocol[IP_PROTOCOL_UDP] = IP_LOCAL_NEXT_UDP_LOOKUP;
    lm->local_next_by_ip_protocol[is_ip6 ? IP_PROTOCOL_ICMP6 : IP_PROTOCOL_ICMP] = IP_LOCAL_NEXT_ICMP;
    lm->builtin_protocol_by_ip_protocol[IP_PROTOCOL_UDP] = IP_BUILTIN_PROTOCOL_UDP;
    lm->builtin_protocol_by_ip_protocol[is_ip6 ? IP_PROTOCOL_ICMP6 : IP_PROTOCOL_ICMP] = IP_BUILTIN_PROTOCOL_ICMP;
  }
}

u8 * format_ip_flow_hash_config (u8 * s, va_list * args)
{
  flow_hash_config_t flow_hash_config = va_arg (*args, u32);
    
#define _(n,v) if (flow_hash_config & v) s = format (s, "%s ", #n);
  foreach_flow_hash_bit;
#undef _

  return s;
}

u8 * format_ip_lookup_next (u8 * s, va_list * args)
{
  ip_lookup_next_t n = va_arg (*args, ip_lookup_next_t);
  char * t = 0;

  switch (n)
    {
    default:
      s = format (s, "unknown %d", n);
      return s;

    case IP_LOOKUP_NEXT_DROP: t = "drop"; break;
    case IP_LOOKUP_NEXT_PUNT: t = "punt"; break;
    case IP_LOOKUP_NEXT_ARP: t = "arp"; break;
    case IP_LOOKUP_NEXT_MIDCHAIN: t="midchain"; break;
    case IP_LOOKUP_NEXT_GLEAN: t="glean"; break;
    case IP_LOOKUP_NEXT_REWRITE:
      break;
    }

  if (t)
    vec_add (s, t, strlen (t));

  return s;
}

u8 * format_ip_adjacency_packet_data (u8 * s, va_list * args)
{
  vnet_main_t * vnm = va_arg (*args, vnet_main_t *);
  u32 adj_index = va_arg (*args, u32);
  u8 * packet_data = va_arg (*args, u8 *);
  u32 n_packet_data_bytes = va_arg (*args, u32);
  ip_adjacency_t * adj = adj_get(adj_index);

  switch (adj->lookup_next_index)
    {
    case IP_LOOKUP_NEXT_REWRITE:
      s = format (s, "%U",
                  format_vnet_rewrite_header,
                  vnm->vlib_main, &adj->rewrite_header, packet_data, n_packet_data_bytes);
      break;

    default:
      break;
    }

  return s;
}

static uword unformat_dpo (unformat_input_t * input, va_list * args)
{
  dpo_id_t *dpo = va_arg (*args, dpo_id_t *);
  fib_protocol_t fp = va_arg (*args, int);
  dpo_proto_t proto;

  proto = fib_proto_to_dpo(fp);

  if (unformat (input, "drop"))
    dpo_copy(dpo, drop_dpo_get(proto));
  else if (unformat (input, "punt"))
    dpo_copy(dpo, punt_dpo_get(proto));
  else if (unformat (input, "local"))
    receive_dpo_add_or_lock(proto, ~0, NULL, dpo);
  else if (unformat (input, "null-send-unreach"))
      ip_null_dpo_add_and_lock(proto, IP_NULL_ACTION_SEND_ICMP_UNREACH, dpo);
  else if (unformat (input, "null-send-prohibit"))
      ip_null_dpo_add_and_lock(proto, IP_NULL_ACTION_SEND_ICMP_PROHIBIT, dpo);
  else if (unformat (input, "null"))
      ip_null_dpo_add_and_lock(proto, IP_NULL_ACTION_NONE, dpo);
  else if (unformat (input, "classify"))
    {
      u32 classify_table_index;

      if (!unformat (input, "%d", &classify_table_index))
        {
          clib_warning ("classify adj must specify table index");
          return 0;
        }

      dpo_set(dpo, DPO_CLASSIFY, proto,
              classify_dpo_create(proto, classify_table_index));
    }
  else
    return 0;

  return 1;
}

const ip46_address_t zero_addr = {
    .as_u64 = {
        0, 0
    },
};

u32
fib_table_id_find_fib_index (fib_protocol_t proto,
                             u32 table_id)
{
    ip4_main_t *im4 = &ip4_main;
    ip6_main_t *im6 = &ip6_main;
    uword * p;

    switch (proto)
    {
    case FIB_PROTOCOL_IP4:
        p = hash_get(im4->fib_index_by_table_id, table_id);
        break;
    case FIB_PROTOCOL_IP6:
        p = hash_get(im6->fib_index_by_table_id, table_id);
        break;
    default:
        p = NULL;
        break;
    }
    if (NULL != p)
    {
        return (p[0]);
    }
    return (~0);
}

clib_error_t *
vnet_ip_route_cmd (vlib_main_t * vm,
                   unformat_input_t * main_input,
                   vlib_cli_command_t * cmd)
{
  unformat_input_t _line_input, * line_input = &_line_input;
  fib_route_path_t *rpaths = NULL, rpath;
  dpo_id_t dpo = DPO_INVALID, *dpos = NULL;
  fib_prefix_t *prefixs = NULL, pfx;
  clib_error_t * error = NULL;
  mpls_label_t out_label;
  u32 table_id, is_del;
  vnet_main_t * vnm;
  u32 fib_index;
  f64 count;
  int i;

  vnm = vnet_get_main();
  is_del = 0;
  table_id = 0;
  count = 1;
  memset(&pfx, 0, sizeof(pfx));

  /* Get a line of input. */
  if (! unformat_user (main_input, unformat_line_input, line_input))
    return 0;

  while (unformat_check_input (line_input) != UNFORMAT_END_OF_INPUT)
    {
      memset(&rpath, 0, sizeof(rpath));

      if (unformat (line_input, "table %d", &table_id))
        ;
      else if (unformat (line_input, "del"))
        is_del = 1;
      else if (unformat (line_input, "add"))
        is_del = 0;
      else if (unformat (line_input, "resolve-via-host"))
      {
          if (vec_len(rpaths) == 0)
          {
              error = clib_error_return(0 , "Paths then flags");
              goto done;
          }
          rpaths[vec_len(rpaths)-1].frp_flags |= FIB_ROUTE_PATH_RESOLVE_VIA_HOST;
      }
      else if (unformat (line_input, "resolve-via-attached"))
      {
          if (vec_len(rpaths) == 0)
          {
              error = clib_error_return(0 , "Paths then flags");
              goto done;
          }
          rpaths[vec_len(rpaths)-1].frp_flags |=
              FIB_ROUTE_PATH_RESOLVE_VIA_ATTACHED;
      }
      else if (unformat (line_input, "out-label %U",
                         unformat_mpls_unicast_label, &out_label))
      {
          if (vec_len(rpaths) == 0)
          {
              error = clib_error_return(0 , "Paths then labels");
              goto done;
          }
          rpaths[vec_len(rpaths)-1].frp_label = out_label;
      }
      else if (unformat (line_input, "count %f", &count))
        ;

      else if (unformat (line_input, "%U/%d",
                         unformat_ip4_address,
                         &pfx.fp_addr.ip4,
                         &pfx.fp_len))
      {
          pfx.fp_proto = FIB_PROTOCOL_IP4;
          vec_add1(prefixs, pfx);
      }
      else if (unformat (line_input, "%U/%d",
                         unformat_ip6_address,
                         &pfx.fp_addr.ip6,
                         &pfx.fp_len))
      {
          pfx.fp_proto = FIB_PROTOCOL_IP6;
          vec_add1(prefixs, pfx);
      }
      else if (unformat (line_input, "via %U %U weight %u",
                         unformat_ip4_address,
                         &rpath.frp_addr.ip4,
                         unformat_vnet_sw_interface, vnm,
                         &rpath.frp_sw_if_index,
                         &rpath.frp_weight))
      {
          rpath.frp_label = MPLS_LABEL_INVALID;
          rpath.frp_proto = FIB_PROTOCOL_IP4;
          vec_add1(rpaths, rpath);
      }

      else if (unformat (line_input, "via %U %U weight %u",
                         unformat_ip6_address,
                         &rpath.frp_addr.ip6,
                         unformat_vnet_sw_interface, vnm,
                         &rpath.frp_sw_if_index,
                         &rpath.frp_weight))
      {
          rpath.frp_label = MPLS_LABEL_INVALID;
          rpath.frp_proto = FIB_PROTOCOL_IP6;
          vec_add1(rpaths, rpath);
      }

      else if (unformat (line_input, "via %U %U",
                         unformat_ip4_address,
                         &rpath.frp_addr.ip4,
                         unformat_vnet_sw_interface, vnm,
                         &rpath.frp_sw_if_index))
      {
          rpath.frp_label = MPLS_LABEL_INVALID;
          rpath.frp_weight = 1;
          rpath.frp_proto = FIB_PROTOCOL_IP4;
          vec_add1(rpaths, rpath);
      }
                         
      else if (unformat (line_input, "via %U %U",
                         unformat_ip6_address,
                         &rpath.frp_addr.ip6,
                         unformat_vnet_sw_interface, vnm,
                         &rpath.frp_sw_if_index))
      {
          rpath.frp_label = MPLS_LABEL_INVALID;
          rpath.frp_weight = 1;
          rpath.frp_proto = FIB_PROTOCOL_IP6;
          vec_add1(rpaths, rpath);
      }
      else if (unformat (line_input, "via %U next-hop-table %d",
                         unformat_ip4_address,
                         &rpath.frp_addr.ip4,
                         &rpath.frp_fib_index))
      {
          rpath.frp_weight = 1;
          rpath.frp_sw_if_index = ~0;
          rpath.frp_label = MPLS_LABEL_INVALID;
          rpath.frp_proto = FIB_PROTOCOL_IP4;
          vec_add1(rpaths, rpath);
      }
      else if (unformat (line_input, "via %U next-hop-table %d",
                         unformat_ip6_address,
                         &rpath.frp_addr.ip6,
                         &rpath.frp_fib_index))
      {
          rpath.frp_weight = 1;
          rpath.frp_sw_if_index = ~0;
          rpath.frp_label = MPLS_LABEL_INVALID;
          rpath.frp_proto = FIB_PROTOCOL_IP6;
          vec_add1(rpaths, rpath);
      }
      else if (unformat (line_input, "via %U",
                         unformat_ip4_address,
                         &rpath.frp_addr.ip4))
      {
          /*
           * the recursive next-hops are by default in the same table
           * as the prefix
           */
          rpath.frp_fib_index = table_id;
          rpath.frp_weight = 1;
          rpath.frp_sw_if_index = ~0;
          rpath.frp_label = MPLS_LABEL_INVALID;
          rpath.frp_proto = FIB_PROTOCOL_IP4;
          vec_add1(rpaths, rpath);
      }
      else if (unformat (line_input, "via %U",
                         unformat_ip6_address,
                         &rpath.frp_addr.ip6))
      {
          rpath.frp_fib_index = table_id;
          rpath.frp_weight = 1;
          rpath.frp_sw_if_index = ~0;
          rpath.frp_label = MPLS_LABEL_INVALID;
          rpath.frp_proto = FIB_PROTOCOL_IP6;
          vec_add1(rpaths, rpath);
      }
      else if (unformat (line_input,
                         "lookup in table %d",
                         &rpath.frp_fib_index))
      {
          rpath.frp_label = MPLS_LABEL_INVALID;
          rpath.frp_proto = pfx.fp_proto;
          rpath.frp_sw_if_index = ~0;
          vec_add1(rpaths, rpath);
      }
      else if (vec_len (prefixs) > 0 &&
               unformat (line_input, "via %U",
                         unformat_dpo, &dpo, prefixs[0].fp_proto))
      {
          rpath.frp_label = MPLS_LABEL_INVALID;
          vec_add1 (dpos, dpo);
      }
      else
      {
          error = unformat_parse_error (line_input);
          goto done;
      }
    }
    
  unformat_free (line_input);

  if (vec_len (prefixs) == 0)
  {
      error = clib_error_return (0, "expected ip4/ip6 destination address/length.");
      goto done;
    }

  if (!is_del && vec_len (rpaths) + vec_len (dpos) == 0)
    {
      error = clib_error_return (0, "expected paths.");
      goto done;
    }

  if (~0 == table_id)
  {
      /*
       * if no table_id is passed we will manipulate the default
       */
      fib_index = 0;
  }
  else
  {
      fib_index = fib_table_id_find_fib_index(prefixs[0].fp_proto,
                                              table_id);

      if (~0 == fib_index)
      {
          error = clib_error_return (0,
                                     "Nonexistent table id %d", 
                                     table_id);
          goto done;
      }
  }

  for (i = 0; i < vec_len (prefixs); i++)
  {
      if (is_del && 0 == vec_len (rpaths))
      {
          fib_table_entry_delete(fib_index,
                                 &prefixs[i],
                                 FIB_SOURCE_CLI);
      }
      else if (!is_del && 1 == vec_len (dpos))
      {
          fib_table_entry_special_dpo_add(fib_index,
                                          &prefixs[i],
                                          FIB_SOURCE_CLI,
                                          FIB_ENTRY_FLAG_EXCLUSIVE,
                                          &dpos[0]);
          dpo_reset(&dpos[0]);
      }
      else if (vec_len (dpos) > 0)
      {
          error = clib_error_return(0 , "Load-balancing over multiple special adjacencies is unsupported");
          goto done;
      }
      else if (0 < vec_len (rpaths))
      {
          u32 k, j, n, incr;
          ip46_address_t dst = prefixs[i].fp_addr;
          f64 t[2];
          n = count;
          t[0] = vlib_time_now (vm);
          incr = 1 << ((FIB_PROTOCOL_IP4 == prefixs[0].fp_proto ? 32 : 128) -
                       prefixs[i].fp_len);

          for (k = 0; k < n; k++)
          {
              for (j = 0; j < vec_len (rpaths); j++)
              {
                  u32 fi;
                  /*
                   * the CLI parsing stored table Ids, swap to FIB indicies
                   */
                  fi = fib_table_id_find_fib_index(prefixs[i].fp_proto,
                                                   rpaths[i].frp_fib_index);

                  if (~0 == fi)
                  {
                      error = clib_error_return(0 , "Via table %d does not exist",
                                                rpaths[i].frp_fib_index);
                      goto done;
                  }
                  rpaths[i].frp_fib_index = fi;

                  fib_prefix_t rpfx = {
                      .fp_len = prefixs[i].fp_len,
                      .fp_proto = prefixs[i].fp_proto,
                      .fp_addr = dst,
                  };

                  if (is_del)
                      fib_table_entry_path_remove2(fib_index,
                                                   &rpfx,
                                                   FIB_SOURCE_CLI,
                                                   &rpaths[j]);
                  else
                      fib_table_entry_path_add2(fib_index,
                                                &rpfx,
                                                FIB_SOURCE_CLI,
                                                FIB_ENTRY_FLAG_NONE,
                                                &rpaths[j]);
              }

              if (FIB_PROTOCOL_IP4 == prefixs[0].fp_proto)
              {
                  dst.ip4.as_u32 =
                      clib_host_to_net_u32(incr +
                                           clib_net_to_host_u32 (dst.ip4.as_u32));
              }
              else
              {
                  int bucket = (incr < 64 ? 0 : 1);
                  dst.ip6.as_u64[bucket] =
                      clib_host_to_net_u64(incr +
                                           clib_net_to_host_u64 (
                                               dst.ip6.as_u64[bucket]));

              }
          }
          t[1] = vlib_time_now (vm);
          if (count > 1)
              vlib_cli_output (vm, "%.6e routes/sec", count / (t[1] - t[0]));
      }
      else
      {
          error = clib_error_return(0 , "Don't understand what you want...");
          goto done;
      }
  }


 done:
  vec_free (dpos);
  vec_free (prefixs);
  vec_free (rpaths);
  return error;
}

VLIB_CLI_COMMAND (vlib_cli_ip_command, static) = {
  .path = "ip",
  .short_help = "Internet protocol (IP) commands",
};

VLIB_CLI_COMMAND (vlib_cli_ip6_command, static) = {
  .path = "ip6",
  .short_help = "Internet protocol version 6 (IPv6) commands",
};

VLIB_CLI_COMMAND (vlib_cli_show_ip_command, static) = {
  .path = "show ip",
  .short_help = "Internet protocol (IP) show commands",
};

VLIB_CLI_COMMAND (vlib_cli_show_ip6_command, static) = {
  .path = "show ip6",
  .short_help = "Internet protocol version 6 (IPv6) show commands",
};

/*?
 * This command is used to add or delete IPv4 or IPv6 routes. All
 * IP Addresses ('<em><dst-ip-addr>/<width></em>',
 * '<em><next-hop-ip-addr></em>' and '<em><adj-hop-ip-addr></em>')
 * can be IPv4 or IPv6, but all must be of the same form in a single
 * command. To display the current set of routes, use the commands
 * '<em>show ip fib</em>' and '<em>show ip6 fib</em>'.
 *
 * @cliexpar
 * Example of how to add a straight forward static route:
 * @cliexcmd{ip route add 6.0.1.2/32 via 6.0.0.1 GigabitEthernet2/0/0}
 * Example of how to delete a straight forward static route:
 * @cliexcmd{ip route del 6.0.1.2/32 via 6.0.0.1 GigabitEthernet2/0/0}
 * Mainly for route add/del performance testing, one can add or delete
 * multiple routes by adding 'count N' to the previous item:
 * @cliexcmd{ip route add count 10 7.0.0.0/24 via 6.0.0.1 GigabitEthernet2/0/0}
 * Add multiple routes for the same destination to create equal-cost multipath:
 * @cliexcmd{ip route add 7.0.0.1/32 via 6.0.0.1 GigabitEthernet2/0/0}
 * @cliexcmd{ip route add 7.0.0.1/32 via 6.0.0.2 GigabitEthernet2/0/0}
 * For unequal-cost multipath, specify the desired weights. This
 * combination of weights results in 3/4 of the traffic following the
 * second path, 1/4 following the first path:
 * @cliexcmd{ip route add 7.0.0.1/32 via 6.0.0.1 GigabitEthernet2/0/0 weight 1}
 * @cliexcmd{ip route add 7.0.0.1/32 via 6.0.0.2 GigabitEthernet2/0/0 weight 3}
 * To add a route to a particular FIB table (VRF), use:
 * @cliexcmd{ip route add 172.16.24.0/24 table 7 via GigabitEthernet2/0/0}
 ?*/
/* *INDENT-OFF* */
VLIB_CLI_COMMAND (ip_route_command, static) = {
  .path = "ip route",
  .short_help = "ip route [add|del] [count <n>] <dst-ip-addr>/<width> [table <table-id>] [via <next-hop-ip-addr> [<interface>] [weight <weight>]] | [via arp <interface> <adj-hop-ip-addr>] | [via drop|punt|local<id>|arp|classify <classify-idx>] [lookup in table <out-table-id>]",
  .function = vnet_ip_route_cmd,
  .is_mp_safe = 1,
};
/* *INDENT-ON* */

/*
 * The next two routines address a longstanding script hemorrhoid.
 * Probing a v4 or v6 neighbor needs to appear to be synchronous,
 * or dependent route-adds will simply fail.
 */
static clib_error_t *
ip6_probe_neighbor_wait (vlib_main_t *vm, ip6_address_t * a, u32 sw_if_index,
                         int retry_count)
{
  vnet_main_t * vnm = vnet_get_main();
  clib_error_t * e;
  int i;
  int resolved = 0;
  uword event_type;
  uword *event_data = 0;

  ASSERT (vlib_in_process_context(vm));

  if (retry_count > 0)
    vnet_register_ip6_neighbor_resolution_event
      (vnm, a, vlib_get_current_process (vm)->node_runtime.node_index,
       1 /* event */, 0 /* data */);

  for (i = 0; i < retry_count; i++)
    {
      /* The interface may be down, etc. */
      e = ip6_probe_neighbor (vm, a, sw_if_index);

      if (e)
        return e;

      vlib_process_wait_for_event_or_clock (vm, 1.0);
      event_type = vlib_process_get_events (vm, &event_data);
      switch (event_type)
        {
        case 1: /* resolved... */
          vlib_cli_output (vm, "Resolved %U",
                           format_ip6_address, a);
          resolved = 1;
          goto done;
          
        case ~0: /* timeout */
          break;
          
        default:
          clib_warning ("unknown event_type %d", event_type);
        }
      vec_reset_length (event_data);
    }
  
 done:

  if (!resolved)
    return clib_error_return (0, "Resolution failed for %U",
                              format_ip6_address, a);
  return 0;
}

static clib_error_t *
ip4_probe_neighbor_wait (vlib_main_t *vm, ip4_address_t * a, u32 sw_if_index,
                         int retry_count)
{
  vnet_main_t * vnm = vnet_get_main();
  clib_error_t * e;
  int i;
  int resolved = 0;
  uword event_type;
  uword *event_data = 0;

  ASSERT (vlib_in_process_context(vm));

  if (retry_count > 0)
    vnet_register_ip4_arp_resolution_event 
      (vnm, a, vlib_get_current_process (vm)->node_runtime.node_index,
       1 /* event */, 0 /* data */);
  
  for (i = 0; i < retry_count; i++)
    {
      /* The interface may be down, etc. */
      e = ip4_probe_neighbor (vm, a, sw_if_index);
      
      if (e)
        return e;
      
      vlib_process_wait_for_event_or_clock (vm, 1.0);
      event_type = vlib_process_get_events (vm, &event_data);
      switch (event_type) 
        {
        case 1: /* resolved... */
          vlib_cli_output (vm, "Resolved %U", 
                           format_ip4_address, a);
          resolved = 1;
          goto done;
          
        case ~0: /* timeout */
          break;
          
        default:
          clib_warning ("unknown event_type %d", event_type);
        }
      vec_reset_length (event_data);
    }
  
 done:

  vec_reset_length (event_data);

  if (!resolved)
    return clib_error_return (0, "Resolution failed for %U",
                              format_ip4_address, a);
  return 0;
}

static clib_error_t *
probe_neighbor_address (vlib_main_t * vm,
                        unformat_input_t * input,
                        vlib_cli_command_t * cmd)
{
  vnet_main_t * vnm = vnet_get_main();
  unformat_input_t _line_input, * line_input = &_line_input;
  ip4_address_t a4;
  ip6_address_t a6;
  clib_error_t * error = 0;
  u32 sw_if_index = ~0;
  int retry_count = 3;
  int is_ip4 = 1;
  int address_set = 0;

  /* Get a line of input. */
  if (! unformat_user (input, unformat_line_input, line_input))
    return 0;

  while (unformat_check_input (line_input) != UNFORMAT_END_OF_INPUT) 
    {
      if (unformat_user (line_input, unformat_vnet_sw_interface, vnm, 
                         &sw_if_index))
        ;
      else if (unformat (line_input, "retry %d", &retry_count))
        ;

      else if (unformat (line_input, "%U", unformat_ip4_address, &a4))
        address_set++;
      else if (unformat (line_input, "%U", unformat_ip6_address, &a6))
        {
          address_set++;
          is_ip4 = 0;
        }
      else
        return clib_error_return (0, "unknown input '%U'",
                                  format_unformat_error, line_input);
    }

  unformat_free (line_input);

  if (sw_if_index == ~0)
    return clib_error_return (0, "Interface required, not set.");
  if (address_set == 0)
    return clib_error_return (0, "ip address required, not set.");
  if (address_set > 1)
    return clib_error_return (0, "Multiple ip addresses not supported.");
    
  if (is_ip4)
    error = ip4_probe_neighbor_wait (vm, &a4, sw_if_index, retry_count);
  else 
    error = ip6_probe_neighbor_wait (vm, &a6, sw_if_index, retry_count);

  return error;
}

/*?
 * The '<em>ip probe-neighbor</em>' command ARPs for IPv4 addresses or
 * attempts IPv6 neighbor discovery depending on the supplied IP address
 * format.
 *
 * @note This command will not immediately affect the indicated FIB; it
 * is not suitable for use in establishing a FIB entry prior to adding
 * recursive FIB entries. As in: don't use it in a script to probe a
 * gateway prior to adding a default route. It won't work. Instead,
 * configure a static ARP cache entry [see '<em>set ip arp</em>'], or
 * a static IPv6 neighbor [see '<em>set ip6 neighbor</em>'].
 *
 * @cliexpar
 * Example of probe for an IPv4 address:
 * @cliexcmd{ip probe-neighbor GigabitEthernet2/0/0 172.16.1.2}
?*/
/* *INDENT-OFF* */
VLIB_CLI_COMMAND (ip_probe_neighbor_command, static) = {
  .path = "ip probe-neighbor",
  .function = probe_neighbor_address,
  .short_help = "ip probe-neighbor <interface> <ip4-addr> | <ip6-addr> [retry nn]",
  .is_mp_safe = 1,
};
/* *INDENT-ON* */