src/vnet/gre/interface.c

/*
 * gre_interface.c: gre interfaces
 *
 * Copyright (c) 2012 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.
 */

#include <vnet/vnet.h>
#include <vnet/pg/pg.h>
#include <vnet/gre/gre.h>
#include <vnet/ip/format.h>
#include <vnet/fib/ip4_fib.h>
#include <vnet/fib/ip6_fib.h>
#include <vnet/adj/adj_midchain.h>
#include <vnet/adj/adj_nbr.h>
#include <vnet/mpls/mpls.h>

static const char *gre_tunnel_type_names[] = GRE_TUNNEL_TYPE_NAMES;

static inline u64
gre4_mk_key (const ip4_address_t * src,
	     const ip4_address_t * dst, u32 out_fib_index)
{
  // FIXME. the fib index should be part of the key
  return ((u64) src->as_u32 << 32 | (u64) dst->as_u32);
}

static u8 *
format_gre_tunnel_type (u8 * s, va_list * args)
{
  gre_tunnel_type_t type = va_arg (*args, gre_tunnel_type_t);

  return (format (s, "%s", gre_tunnel_type_names[type]));
}

static u8 *
format_gre_tunnel (u8 * s, va_list * args)
{
  gre_tunnel_t *t = va_arg (*args, gre_tunnel_t *);
  gre_main_t *gm = &gre_main;
  u8 is_ipv6 = t->tunnel_dst.fp_proto == FIB_PROTOCOL_IP6 ? 1 : 0;

  if (!is_ipv6)
    s = format (s,
		"[%d] %U (src) %U (dst) payload %U outer_fib_index %d",
		t - gm->tunnels,
		format_ip4_address, &t->tunnel_src.ip4,
		format_ip4_address, &t->tunnel_dst.fp_addr.ip4,
		format_gre_tunnel_type, t->type, t->outer_fib_index);
  else
    s = format (s,
		"[%d] %U (src) %U (dst) payload %U outer_fib_index %d",
		t - gm->tunnels,
		format_ip6_address, &t->tunnel_src.ip6,
		format_ip6_address, &t->tunnel_dst.fp_addr.ip6,
		format_gre_tunnel_type, t->type, t->outer_fib_index);

  return s;
}

static gre_tunnel_t *
gre_tunnel_db_find (const ip46_address_t * src,
		    const ip46_address_t * dst, u32 out_fib_index, u8 is_ipv6)
{
  gre_main_t *gm = &gre_main;
  uword *p;
  u64 key4, key6[4];

  if (!is_ipv6)
    {
      key4 = gre4_mk_key (&src->ip4, &dst->ip4, out_fib_index);
      p = hash_get (gm->tunnel_by_key4, key4);
    }
  else
    {
      key6[0] = src->ip6.as_u64[0];
      key6[1] = src->ip6.as_u64[1];
      key6[2] = dst->ip6.as_u64[0];
      key6[3] = dst->ip6.as_u64[1];
      p = hash_get_mem (gm->tunnel_by_key6, key6);
    }

  if (NULL == p)
    return (NULL);

  return (pool_elt_at_index (gm->tunnels, p[0]));
}

static void
gre_tunnel_db_add (const gre_tunnel_t * t)
{
  gre_main_t *gm = &gre_main;
  u64 key4, key6[4], *key6_copy;
  u8 is_ipv6 = t->tunnel_dst.fp_proto == FIB_PROTOCOL_IP6 ? 1 : 0;

  if (!is_ipv6)
    {
      key4 = gre4_mk_key (&t->tunnel_src.ip4, &t->tunnel_dst.fp_addr.ip4,
			  t->outer_fib_index);
      hash_set (gm->tunnel_by_key4, key4, t - gm->tunnels);
    }
  else
    {
      key6[0] = t->tunnel_src.ip6.as_u64[0];
      key6[1] = t->tunnel_src.ip6.as_u64[1];
      key6[2] = t->tunnel_dst.fp_addr.ip6.as_u64[0];
      key6[3] = t->tunnel_dst.fp_addr.ip6.as_u64[1];
      key6_copy = clib_mem_alloc (sizeof (key6));
      clib_memcpy (key6_copy, key6, sizeof (key6));
      hash_set_mem (gm->tunnel_by_key6, key6_copy, t - gm->tunnels);
    }
}

static void
gre_tunnel_db_remove (const gre_tunnel_t * t)
{
  gre_main_t *gm = &gre_main;
  u64 key4, key6[4];
  u8 is_ipv6 = t->tunnel_dst.fp_proto == FIB_PROTOCOL_IP6 ? 1 : 0;

  if (!is_ipv6)
    {
      key4 = gre4_mk_key (&t->tunnel_src.ip4, &t->tunnel_dst.fp_addr.ip4,
			  t->outer_fib_index);
      hash_unset (gm->tunnel_by_key4, key4);
    }
  else
    {
      key6[0] = t->tunnel_src.ip6.as_u64[0];
      key6[1] = t->tunnel_src.ip6.as_u64[1];
      key6[2] = t->tunnel_dst.fp_addr.ip6.as_u64[0];
      key6[3] = t->tunnel_dst.fp_addr.ip6.as_u64[1];
      hash_unset_mem (gm->tunnel_by_key6, key6);
    }

}

static gre_tunnel_t *
gre_tunnel_from_fib_node (fib_node_t * node)
{
  ASSERT (FIB_NODE_TYPE_GRE_TUNNEL == node->fn_type);
  return ((gre_tunnel_t *) (((char *) node) -
			    STRUCT_OFFSET_OF (gre_tunnel_t, node)));
}

/**
 * gre_tunnel_stack
 *
 * 'stack' (resolve the recursion for) the tunnel's midchain adjacency
 */
void
gre_tunnel_stack (adj_index_t ai)
{
  gre_main_t *gm = &gre_main;
  ip_adjacency_t *adj;
  gre_tunnel_t *gt;
  u32 sw_if_index;

  adj = adj_get (ai);
  sw_if_index = adj->rewrite_header.sw_if_index;

  if ((vec_len (gm->tunnel_index_by_sw_if_index) < sw_if_index) ||
      (~0 == gm->tunnel_index_by_sw_if_index[sw_if_index]))
    return;

  gt = pool_elt_at_index (gm->tunnels,
			  gm->tunnel_index_by_sw_if_index[sw_if_index]);

  /*
   * find the adjacency that is contributed by the FIB entry
   * that this tunnel resovles via, and use it as the next adj
   * in the midchain
   */
  if (vnet_hw_interface_get_flags (vnet_get_main (),
				   gt->hw_if_index) &
      VNET_HW_INTERFACE_FLAG_LINK_UP)
    {
      adj_nbr_midchain_stack (ai,
			      fib_entry_contribute_ip_forwarding
			      (gt->fib_entry_index));
    }
  else
    {
      adj_nbr_midchain_unstack (ai);
    }
}

/**
 * @brief Call back when restacking all adjacencies on a GRE interface
 */
static adj_walk_rc_t
gre_adj_walk_cb (adj_index_t ai, void *ctx)
{
  gre_tunnel_stack (ai);

  return (ADJ_WALK_RC_CONTINUE);
}

static void
gre_tunnel_restack (gre_tunnel_t * gt)
{
  fib_protocol_t proto;

  /*
   * walk all the adjacencies on th GRE interface and restack them
   */
  FOR_EACH_FIB_IP_PROTOCOL (proto)
  {
    adj_nbr_walk (gt->sw_if_index, proto, gre_adj_walk_cb, NULL);
  }
}

/**
 * Function definition to backwalk a FIB node
 */
static fib_node_back_walk_rc_t
gre_tunnel_back_walk (fib_node_t * node, fib_node_back_walk_ctx_t * ctx)
{
  gre_tunnel_restack (gre_tunnel_from_fib_node (node));

  return (FIB_NODE_BACK_WALK_CONTINUE);
}

/**
 * Function definition to get a FIB node from its index
 */
static fib_node_t *
gre_tunnel_fib_node_get (fib_node_index_t index)
{
  gre_tunnel_t *gt;
  gre_main_t *gm;

  gm = &gre_main;
  gt = pool_elt_at_index (gm->tunnels, index);

  return (&gt->node);
}

/**
 * Function definition to inform the FIB node that its last lock has gone.
 */
static void
gre_tunnel_last_lock_gone (fib_node_t * node)
{
  /*
   * The MPLS GRE tunnel is a root of the graph. As such
   * it never has children and thus is never locked.
   */
  ASSERT (0);
}

/*
 * Virtual function table registered by MPLS GRE tunnels
 * for participation in the FIB object graph.
 */
const static fib_node_vft_t gre_vft = {
  .fnv_get = gre_tunnel_fib_node_get,
  .fnv_last_lock = gre_tunnel_last_lock_gone,
  .fnv_back_walk = gre_tunnel_back_walk,
};

static int
vnet_gre_tunnel_add (vnet_gre_add_del_tunnel_args_t * a, u32 * sw_if_indexp)
{
  gre_main_t *gm = &gre_main;
  vnet_main_t *vnm = gm->vnet_main;
  ip4_main_t *im4 = &ip4_main;
  ip6_main_t *im6 = &ip6_main;
  gre_tunnel_t *t;
  vnet_hw_interface_t *hi;
  u32 hw_if_index, sw_if_index;
  u32 outer_fib_index;
  u8 address[6];
  clib_error_t *error;
  u8 is_ipv6 = a->is_ipv6;

  if (!is_ipv6)
    outer_fib_index = ip4_fib_index_from_table_id (a->outer_fib_id);
  else
    outer_fib_index = ip6_fib_index_from_table_id (a->outer_fib_id);

  if (~0 == outer_fib_index)
    return VNET_API_ERROR_NO_SUCH_FIB;

  t = gre_tunnel_db_find (&a->src, &a->dst, a->outer_fib_id, a->is_ipv6);

  if (NULL != t)
    return VNET_API_ERROR_INVALID_VALUE;

  pool_get_aligned (gm->tunnels, t, CLIB_CACHE_LINE_BYTES);
  memset (t, 0, sizeof (*t));
  fib_node_init (&t->node, FIB_NODE_TYPE_GRE_TUNNEL);

  if (a->teb)
    t->type = GRE_TUNNEL_TYPE_TEB;
  else
    t->type = GRE_TUNNEL_TYPE_L3;

  if (vec_len (gm->free_gre_tunnel_hw_if_indices[t->type]) > 0)
    {
      vnet_interface_main_t *im = &vnm->interface_main;

      hw_if_index = gm->free_gre_tunnel_hw_if_indices[t->type]
	[vec_len (gm->free_gre_tunnel_hw_if_indices[t->type]) - 1];
      _vec_len (gm->free_gre_tunnel_hw_if_indices[t->type]) -= 1;

      hi = vnet_get_hw_interface (vnm, hw_if_index);
      hi->dev_instance = t - gm->tunnels;
      hi->hw_instance = hi->dev_instance;

      /* clear old stats of freed tunnel before reuse */
      sw_if_index = hi->sw_if_index;
      vnet_interface_counter_lock (im);
      vlib_zero_combined_counter
	(&im->combined_sw_if_counters[VNET_INTERFACE_COUNTER_TX],
	 sw_if_index);
      vlib_zero_combined_counter (&im->combined_sw_if_counters
				  [VNET_INTERFACE_COUNTER_RX], sw_if_index);
      vlib_zero_simple_counter (&im->sw_if_counters
				[VNET_INTERFACE_COUNTER_DROP], sw_if_index);
      vnet_interface_counter_unlock (im);
      if (GRE_TUNNEL_TYPE_TEB == t->type)
	{
	  t->l2_tx_arc = vlib_node_add_named_next (vlib_get_main (),
						   hi->tx_node_index,
						   "adj-l2-midchain");
	}
    }
  else
    {
      if (GRE_TUNNEL_TYPE_TEB == t->type)
	{
	  /* Default MAC address (d00b:eed0:0000 + sw_if_index) */
	  memset (address, 0, sizeof (address));
	  address[0] = 0xd0;
	  address[1] = 0x0b;
	  address[2] = 0xee;
	  address[3] = 0xd0;
	  address[4] = t - gm->tunnels;

	  error = ethernet_register_interface (vnm,
					       gre_device_teb_class.index,
					       t - gm->tunnels, address,
					       &hw_if_index, 0);

	  if (error)
	    {
	      clib_error_report (error);
	      return VNET_API_ERROR_INVALID_REGISTRATION;
	    }
	  hi = vnet_get_hw_interface (vnm, hw_if_index);

	  t->l2_tx_arc = vlib_node_add_named_next (vlib_get_main (),
						   hi->tx_node_index,
						   "adj-l2-midchain");
	}
      else
	{
	  hw_if_index = vnet_register_interface (vnm,
						 gre_device_class.index,
						 t - gm->tunnels,
						 gre_hw_interface_class.index,
						 t - gm->tunnels);
	}
      hi = vnet_get_hw_interface (vnm, hw_if_index);
      sw_if_index = hi->sw_if_index;
    }

  t->hw_if_index = hw_if_index;
  t->outer_fib_index = outer_fib_index;
  t->sw_if_index = sw_if_index;
  t->l2_adj_index = ADJ_INDEX_INVALID;

  vec_validate_init_empty (gm->tunnel_index_by_sw_if_index, sw_if_index, ~0);
  gm->tunnel_index_by_sw_if_index[sw_if_index] = t - gm->tunnels;

  if (!is_ipv6)
    {
      vec_validate (im4->fib_index_by_sw_if_index, sw_if_index);
      hi->min_packet_bytes =
	64 + sizeof (gre_header_t) + sizeof (ip4_header_t);
    }
  else
    {
      vec_validate (im6->fib_index_by_sw_if_index, sw_if_index);
      hi->min_packet_bytes =
	64 + sizeof (gre_header_t) + sizeof (ip6_header_t);
    }

  hi->per_packet_overhead_bytes =
    /* preamble */ 8 + /* inter frame gap */ 12;

  /* Standard default gre MTU. */
  hi->max_l3_packet_bytes[VLIB_RX] = hi->max_l3_packet_bytes[VLIB_TX] = 9000;

  /*
   * source the FIB entry for the tunnel's destination
   * and become a child thereof. The tunnel will then get poked
   * when the forwarding for the entry updates, and the tunnel can
   * re-stack accordingly
   */

  clib_memcpy (&t->tunnel_src, &a->src, sizeof (t->tunnel_src));
  t->tunnel_dst.fp_len = !is_ipv6 ? 32 : 128;
  t->tunnel_dst.fp_proto = !is_ipv6 ? FIB_PROTOCOL_IP4 : FIB_PROTOCOL_IP6;
  t->tunnel_dst.fp_addr = a->dst;

  gre_tunnel_db_add (t);

  t->fib_entry_index =
    fib_table_entry_special_add (outer_fib_index,
				 &t->tunnel_dst,
				 FIB_SOURCE_RR, FIB_ENTRY_FLAG_NONE);
  t->sibling_index =
    fib_entry_child_add (t->fib_entry_index,
			 FIB_NODE_TYPE_GRE_TUNNEL, t - gm->tunnels);

  if (GRE_TUNNEL_TYPE_TEB == t->type)
    {
      t->l2_adj_index = adj_nbr_add_or_lock (t->tunnel_dst.fp_proto,
					     VNET_LINK_ETHERNET,
					     &zero_addr, sw_if_index);
      gre_update_adj (vnm, t->sw_if_index, t->l2_adj_index);
    }

  if (sw_if_indexp)
    *sw_if_indexp = sw_if_index;

  return 0;
}

static int
vnet_gre_tunnel_delete (vnet_gre_add_del_tunnel_args_t * a,
			u32 * sw_if_indexp)
{
  gre_main_t *gm = &gre_main;
  vnet_main_t *vnm = gm->vnet_main;
  gre_tunnel_t *t;
  u32 sw_if_index;

  t = gre_tunnel_db_find (&a->src, &a->dst, a->outer_fib_id, a->is_ipv6);

  if (NULL == t)
    return VNET_API_ERROR_NO_SUCH_ENTRY;

  sw_if_index = t->sw_if_index;
  vnet_sw_interface_set_flags (vnm, sw_if_index, 0 /* down */ );
  /* make sure tunnel is removed from l2 bd or xconnect */
  set_int_l2_mode (gm->vlib_main, vnm, MODE_L3, sw_if_index, 0, 0, 0, 0);
  vec_add1 (gm->free_gre_tunnel_hw_if_indices[t->type], t->hw_if_index);
  gm->tunnel_index_by_sw_if_index[sw_if_index] = ~0;

  if (GRE_TUNNEL_TYPE_TEB == t->type)
    adj_unlock (t->l2_adj_index);

  if (t->l2_adj_index != ADJ_INDEX_INVALID)
    adj_unlock (t->l2_adj_index);

  fib_entry_child_remove (t->fib_entry_index, t->sibling_index);
  fib_table_entry_delete_index (t->fib_entry_index, FIB_SOURCE_RR);

  gre_tunnel_db_remove (t);
  fib_node_deinit (&t->node);
  pool_put (gm->tunnels, t);

  if (sw_if_indexp)
    *sw_if_indexp = sw_if_index;

  return 0;
}

int
vnet_gre_add_del_tunnel (vnet_gre_add_del_tunnel_args_t * a,
			 u32 * sw_if_indexp)
{
  if (a->is_add)
    return (vnet_gre_tunnel_add (a, sw_if_indexp));
  else
    return (vnet_gre_tunnel_delete (a, sw_if_indexp));
}

clib_error_t *
gre_interface_admin_up_down (vnet_main_t * vnm, u32 hw_if_index, u32 flags)
{
  gre_main_t *gm = &gre_main;
  vnet_hw_interface_t *hi;
  gre_tunnel_t *t;
  u32 ti;

  hi = vnet_get_hw_interface (vnm, hw_if_index);

  if (NULL == gm->tunnel_index_by_sw_if_index ||
      hi->sw_if_index >= vec_len (gm->tunnel_index_by_sw_if_index))
    return (NULL);

  ti = gm->tunnel_index_by_sw_if_index[hi->sw_if_index];

  if (~0 == ti)
    /* not one of ours */
    return (NULL);

  t = pool_elt_at_index (gm->tunnels, ti);

  if (flags & VNET_SW_INTERFACE_FLAG_ADMIN_UP)
    vnet_hw_interface_set_flags (vnm, hw_if_index,
				 VNET_HW_INTERFACE_FLAG_LINK_UP);
  else
    vnet_hw_interface_set_flags (vnm, hw_if_index, 0 /* down */ );

  gre_tunnel_restack (t);

  return /* no error */ 0;
}

static clib_error_t *
create_gre_tunnel_command_fn (vlib_main_t * vm,
			      unformat_input_t * input,
			      vlib_cli_command_t * cmd)
{
  unformat_input_t _line_input, *line_input = &_line_input;
  vnet_gre_add_del_tunnel_args_t _a, *a = &_a;
  ip46_address_t src, dst;
  u32 outer_fib_id = 0;
  u8 teb = 0;
  int rv;
  u32 num_m_args = 0;
  u8 is_add = 1;
  u32 sw_if_index;
  clib_error_t *error = NULL;
  u8 ipv4_set = 0;
  u8 ipv6_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 (line_input, "del"))
	is_add = 0;
      else
	if (unformat (line_input, "src %U", unformat_ip4_address, &src.ip4))
	{
	  num_m_args++;
	  ipv4_set = 1;
	}
      else
	if (unformat (line_input, "dst %U", unformat_ip4_address, &dst.ip4))
	{
	  num_m_args++;
	  ipv4_set = 1;
	}
      else
	if (unformat (line_input, "src %U", unformat_ip6_address, &src.ip6))
	{
	  num_m_args++;
	  ipv6_set = 1;
	}
      else
	if (unformat (line_input, "dst %U", unformat_ip6_address, &dst.ip6))
	{
	  num_m_args++;
	  ipv6_set = 1;
	}
      else if (unformat (line_input, "outer-fib-id %d", &outer_fib_id))
	;
      else if (unformat (line_input, "teb"))
	teb = 1;
      else
	{
	  error = clib_error_return (0, "unknown input `%U'",
				     format_unformat_error, line_input);
	  goto done;
	}
    }

  if (num_m_args < 2)
    {
      error = clib_error_return (0, "mandatory argument(s) missing");
      goto done;
    }

  if ((ipv4_set && memcmp (&src.ip4, &dst.ip4, sizeof (src.ip4)) == 0) ||
      (ipv6_set && memcmp (&src.ip6, &dst.ip6, sizeof (src.ip6)) == 0))
    {
      error = clib_error_return (0, "src and dst are identical");
      goto done;
    }

  if (ipv4_set && ipv6_set)
    return clib_error_return (0, "both IPv4 and IPv6 addresses specified");

  if ((ipv4_set && memcmp (&dst.ip4, &zero_addr.ip4, sizeof (dst.ip4)) == 0)
      || (ipv6_set
	  && memcmp (&dst.ip6, &zero_addr.ip6, sizeof (dst.ip6)) == 0))
    {
      error = clib_error_return (0, "dst address cannot be zero");
      goto done;
    }

  memset (a, 0, sizeof (*a));
  a->outer_fib_id = outer_fib_id;
  a->teb = teb;
  a->is_ipv6 = ipv6_set;
  if (!ipv6_set)
    {
      clib_memcpy (&a->src.ip4, &src.ip4, sizeof (src.ip4));
      clib_memcpy (&a->dst.ip4, &dst.ip4, sizeof (dst.ip4));
    }
  else
    {
      clib_memcpy (&a->src.ip6, &src.ip6, sizeof (src.ip6));
      clib_memcpy (&a->dst.ip6, &dst.ip6, sizeof (dst.ip6));
    }

  if (is_add)
    rv = vnet_gre_tunnel_add (a, &sw_if_index);
  else
    rv = vnet_gre_tunnel_delete (a, &sw_if_index);

  switch (rv)
    {
    case 0:
      vlib_cli_output (vm, "%U\n", format_vnet_sw_if_index_name,
		       vnet_get_main (), sw_if_index);
      break;
    case VNET_API_ERROR_INVALID_VALUE:
      error = clib_error_return (0, "GRE tunnel already exists...");
      goto done;
    case VNET_API_ERROR_NO_SUCH_FIB:
      error = clib_error_return (0, "outer fib ID %d doesn't exist\n",
				 outer_fib_id);
      goto done;
    default:
      error =
	clib_error_return (0, "vnet_gre_add_del_tunnel returned %d", rv);
      goto done;
    }

done:
  unformat_free (line_input);

  return error;
}

/* *INDENT-OFF* */
VLIB_CLI_COMMAND (create_gre_tunnel_command, static) = {
  .path = "create gre tunnel",
  .short_help = "create gre tunnel src <addr> dst <addr> "
                "[outer-fib-id <fib>] [teb] [del]",
  .function = create_gre_tunnel_command_fn,
};
/* *INDENT-ON* */

static clib_error_t *
show_gre_tunnel_command_fn (vlib_main_t * vm,
			    unformat_input_t * input,
			    vlib_cli_command_t * cmd)
{
  gre_main_t *gm = &gre_main;
  gre_tunnel_t *t;
  u32 ti = ~0;

  if (pool_elts (gm->tunnels) == 0)
    vlib_cli_output (vm, "No GRE tunnels configured...");

  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
    {
      if (unformat (input, "%d", &ti))
	;
      else
	break;
    }

  if (~0 == ti)
    {
      /* *INDENT-OFF* */
      pool_foreach (t, gm->tunnels,
      ({
          vlib_cli_output (vm, "%U", format_gre_tunnel, t);
      }));
      /* *INDENT-ON* */
    }
  else
    {
      t = pool_elt_at_index (gm->tunnels, ti);

      vlib_cli_output (vm, "%U", format_gre_tunnel, t);
    }

  return 0;
}

/* *INDENT-OFF* */
VLIB_CLI_COMMAND (show_gre_tunnel_command, static) = {
    .path = "show gre tunnel",
    .function = show_gre_tunnel_command_fn,
};
/* *INDENT-ON* */

/* force inclusion from application's main.c */
clib_error_t *
gre_interface_init (vlib_main_t * vm)
{
  fib_node_register_type (FIB_NODE_TYPE_GRE_TUNNEL, &gre_vft);

  return 0;
}

VLIB_INIT_FUNCTION (gre_interface_init);

/*
 * fd.io coding-style-patch-verification: ON
 *
 * Local Variables:
 * eval: (c-set-style "gnu")
 * End:
 */