text: /*
   * Copyright (c) 2018 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.
   */
  /**
   * This code supports the following sixrd modes:
   *
   * 32 EA bits (Complete IPv4 address is embedded):
   *   ea_bits_len = 32
   * IPv4 suffix is embedded:
   *   ea_bits_len = < 32
   * No embedded address bits (1:1 mode):
   *   ea_bits_len = 0
   */
  
  #include "sixrd.h"
  #include <vnet/plugin/plugin.h>
  #include <vlibapi/api.h>
  #include <vlibmemory/api.h>
  #include <vnet/adj/adj.h>
  #include <vnet/fib/fib_table.h>
  #include <vnet/fib/ip6_fib.h>
  #include <vnet/adj/adj_midchain.h>
  #include <vnet/adj/adj_delegate.h>
  #include <vnet/dpo/lookup_dpo.h>
  #include <vpp/app/version.h>	// Really needed?
  
  /* define message IDs */
  #include "sixrd_msg_enum.h"
  
  /* define message structures */
  #define vl_typedefs
  #include "sixrd_all_api_h.h"
  #undef vl_typedefs
  
  /* define generated endian-swappers */
  #define vl_endianfun
  #include "sixrd_all_api_h.h"
  #undef vl_endianfun
  
  /* instantiate all the print functions we know about */
  #define vl_print(handle, ...) vlib_cli_output(handle, __VA_ARGS__)
  #define vl_printfun
  #include "sixrd_all_api_h.h"
  #undef vl_printfun
  
  /* Get the API version number */
  #define vl_api_version(n, v) static u32 api_version = (v);
  #include "sixrd_all_api_h.h"
  #undef vl_api_version
  
  #define REPLY_MSG_ID_BASE sm->msg_id_base
  #include <vlibapi/api_helper_macros.h>
  
  extern vlib_node_registration_t ip4_sixrd_node;
  
  /**
   * Adj delegate data
   */
  typedef struct sixrd_adj_delegate_t_
  {
      /**
       * linkage to the adj
       */
    u32 adj_index;
  
      /**
       * Linnkage to the FIB node graph
       */
    fib_node_t sixrd_node;
  
      /**
       * tracking of the IPv4 next-hop
       */
    fib_node_index_t sixrd_fib_entry_index;
  
      /**
       * sibling on the fib-entry
       */
    u32 sixrd_sibling;
  } sixrd_adj_delegate_t;
  
  /**
   * Pool of delegate structs
   */
  static sixrd_adj_delegate_t *sixrd_adj_delegate_pool;
  
  /**
   * Adj delegate registered type
   */
  static adj_delegate_type_t sixrd_adj_delegate_type;
  
  /**
   * FIB node registered type
   */
  static fib_node_type_t sixrd_fib_node_type;
  
  static inline sixrd_adj_delegate_t *
  sixrd_adj_from_base (adj_delegate_t * ad)
  {
    if (NULL == ad)
      {
        return (NULL);
      }
    return (pool_elt_at_index (sixrd_adj_delegate_pool, ad->ad_index));
  }
  
  static inline const sixrd_adj_delegate_t *
  sixrd_adj_from_const_base (const adj_delegate_t * ad)
  {
    if (NULL == ad)
      {
        return (NULL);
      }
    return (pool_elt_at_index (sixrd_adj_delegate_pool, ad->ad_index));
  }
  
  sixrd_main_t sixrd_main;
  
  static void
  sixrd_fixup (vlib_main_t * vm,
  	     ip_adjacency_t * adj, vlib_buffer_t * b0, const void *data)
  {
    ip4_header_t *ip4 = vlib_buffer_get_current (b0);
    ip6_header_t *ip6 = vlib_buffer_get_current (b0) + sizeof (ip4_header_t);
    const sixrd_tunnel_t *t = data;
  
    ip4->length = clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, b0));
    ip4->dst_address.as_u32 =
      sixrd_get_addr_net (t, ip6->dst_address.as_u64[0]);
    ip4->checksum = ip4_header_checksum (ip4);
  }
  
  static void
  ip6ip_fixup (vlib_main_t * vm,
  	     ip_adjacency_t * adj, vlib_buffer_t * b0, const void *data)
  {
    const sixrd_tunnel_t *t = data;
    ip4_header_t *ip4 = vlib_buffer_get_current (b0);
    ip4->length = clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, b0));
    ip4->dst_address.as_u32 =
      sixrd_get_addr_net (t, adj->sub_type.nbr.next_hop.as_u64[0]);
    ip4->checksum = ip4_header_checksum (ip4);
  }
  
  static sixrd_tunnel_t *
  find_tunnel_by_sw_if_index (u32 sw_if_index)
  {
    sixrd_main_t *sm = &sixrd_main;
    u32 ti = sm->tunnel_index_by_sw_if_index[sw_if_index];
    if (ti == ~0)
      {
        clib_warning ("Not our tunnel\n");
        return (0);
      }
    return pool_elt_at_index (sm->tunnels, ti);
  }
  
  static sixrd_tunnel_t *
  find_tunnel (ip6_address_t * ip6_prefix)
  {
    sixrd_main_t *sm = &sixrd_main;
    sixrd_tunnel_t *d;
  
    /* *INDENT-OFF* */
    pool_foreach (d, sm->tunnels,
    ({
      if (!memcmp (&d->ip6_prefix, ip6_prefix, 16))
        return d;
    }));
    /* *INDENT-ON* */
    return 0;
  }
  
  
  static u8 *
  sixrd_build_rewrite (vnet_main_t * vnm,
  		     u32 sw_if_index,
  		     vnet_link_t link_type, const void *dst_address)
  {
    u8 *rewrite = NULL;
    sixrd_tunnel_t *t;
  
    t = find_tunnel_by_sw_if_index (sw_if_index);
    if (!t)
      {
        return 0;
      }
  
    vec_validate (rewrite, sizeof (ip4_header_t) - 1);
    ip4_header_t *ip4 = (ip4_header_t *) rewrite;
    ip4->ip_version_and_header_length = 0x45;
    ip4->ttl = 64;
    ip4->protocol = IP_PROTOCOL_IPV6;
    /* fixup ip4 header length and checksum after-the-fact */
    ip4->src_address.as_u32 = t->ip4_src.as_u32;
    ip4->dst_address.as_u32 = 0;
    ip4->checksum = ip4_header_checksum (ip4);
  
    return rewrite;
  }
  
  static void
  ip6ip_tunnel_stack (adj_index_t ai, u32 fib_entry_index)
  {
    sixrd_main_t *sm = &sixrd_main;
    ip_adjacency_t *adj = adj_get (ai);
    sixrd_tunnel_t *t;
    u32 sw_if_index = adj->rewrite_header.sw_if_index;
  
    if ((vec_len (sm->tunnel_index_by_sw_if_index) < sw_if_index) ||
        (~0 == sm->tunnel_index_by_sw_if_index[sw_if_index]))
      return;
  
    t =
      pool_elt_at_index (sm->tunnels,
  		       sm->tunnel_index_by_sw_if_index[sw_if_index]);
  
    /*
     * find the adjacency that is contributed by the FIB entry
     * that this tunnel resolves via, and use it as the next adj
     * in the midchain
     */
    if (vnet_hw_interface_get_flags (vnet_get_main (), t->hw_if_index) &
        VNET_HW_INTERFACE_FLAG_LINK_UP)
      {
        adj_nbr_midchain_stack (ai,
  			      fib_entry_contribute_ip_forwarding
  			      (fib_entry_index));
      }
    else
      {
        adj_nbr_midchain_unstack (ai);
      }
  }
  
  static void
  sixrd_tunnel_stack (adj_index_t ai, u32 fib_index)
  {
    dpo_id_t dpo = DPO_INVALID;
    sixrd_main_t *sm = &sixrd_main;
    ip_adjacency_t *adj = adj_get (ai);
    u32 sw_if_index = adj->rewrite_header.sw_if_index;
  
    if ((vec_len (sm->tunnel_index_by_sw_if_index) < sw_if_index) ||
        (~0 == sm->tunnel_index_by_sw_if_index[sw_if_index]))
      return;
  
    if ((vec_len (sm->tunnel_index_by_sw_if_index) < sw_if_index) ||
        (sm->tunnel_index_by_sw_if_index[sw_if_index] == ~0))
      return;
  
    lookup_dpo_add_or_lock_w_fib_index (fib_index, DPO_PROTO_IP4,
  				      LOOKUP_UNICAST, LOOKUP_INPUT_DST_ADDR,
  				      LOOKUP_TABLE_FROM_CONFIG, &dpo);
    adj_nbr_midchain_stack (ai, &dpo);
  }
  
  const static ip46_address_t sixrd_special_nh = {
    .ip6 = {
  	  .as_u64 = {
  		     [0] = 0xffffffffffffffff,
  		     [1] = 0xffffffffffffffff,
  		     },
  	  },
  };
  
  static void
  sixrd_update_adj (vnet_main_t * vnm, u32 sw_if_index, adj_index_t ai)
  {
    ip_adjacency_t *adj = adj_get (ai);
    sixrd_tunnel_t *t = find_tunnel_by_sw_if_index (sw_if_index);
  
    if (!memcmp (&sixrd_special_nh,
  	       &adj->sub_type.nbr.next_hop, sizeof (sixrd_special_nh)))
      {
        adj_nbr_midchain_update_rewrite (ai, sixrd_fixup, t, ADJ_FLAG_NONE,
  				       sixrd_build_rewrite (vnm, sw_if_index,
  							    adj_get_link_type
  							    (ai), NULL));
        sixrd_tunnel_stack (ai, t->fib_index);
      }
    else
      {
        sixrd_adj_delegate_t *sixrd_ad;
        ip4_address_t da4;
  
        da4.as_u32 =
  	sixrd_get_addr_net (t, adj->sub_type.nbr.next_hop.as_u64[0]);
  
        fib_prefix_t pfx = {
  	.fp_proto = FIB_PROTOCOL_IP4,
  	.fp_len = 32,
  	.fp_addr = {.ip4 = da4,}
  	,
        };
  
        adj_nbr_midchain_update_rewrite
  	(ai, ip6ip_fixup, t,
  	 ADJ_FLAG_NONE,
  	 sixrd_build_rewrite (vnm, sw_if_index,
  			      adj_get_link_type (ai), NULL));
  
        sixrd_ad =
  	sixrd_adj_from_base (adj_delegate_get (adj, sixrd_adj_delegate_type));
        if (NULL == sixrd_ad)
  	{
  	  pool_get (sixrd_adj_delegate_pool, sixrd_ad);
  	  fib_node_init (&sixrd_ad->sixrd_node, sixrd_fib_node_type);
  	  sixrd_ad->adj_index = ai;
  	  sixrd_ad->sixrd_fib_entry_index =
  	    fib_table_entry_special_add (t->fib_index, &pfx,
  					 FIB_SOURCE_RR, FIB_ENTRY_FLAG_NONE);
  	  sixrd_ad->sixrd_sibling =
  	    fib_entry_child_add (sixrd_ad->sixrd_fib_entry_index,
  				 sixrd_fib_node_type,
  				 sixrd_ad - sixrd_adj_delegate_pool);
  
  	  adj_delegate_add (adj,
  			    sixrd_adj_delegate_type,
  			    sixrd_ad - sixrd_adj_delegate_pool);
  
  	  ip6ip_tunnel_stack (ai, sixrd_ad->sixrd_fib_entry_index);
  	}
      }
  }
  
  
  clib_error_t *
  sixrd_interface_admin_up_down (vnet_main_t * vnm, u32 hw_if_index, u32 flags)
  {
    /* Always up */
    vnet_hw_interface_set_flags (vnm, hw_if_index,
  			       VNET_HW_INTERFACE_FLAG_LINK_UP);
    return /* no error */ 0;
  }
  
  /* *INDENT-OFF* */
  VNET_HW_INTERFACE_CLASS (sixrd_hw_interface_class) =
  {
    .name = "ip6ip-6rd",
    .build_rewrite = sixrd_build_rewrite,
    .update_adjacency = sixrd_update_adj,
  };
  
  VNET_DEVICE_CLASS (sixrd_device_class) =
  {
    .name = "ip6ip-6rd",
    .admin_up_down_function = sixrd_interface_admin_up_down,
  #ifdef SOON
    .clear counter = 0;
  #endif
  };
  /* *INDENT-ON* */
  
  static int
  sixrd_create_tunnel (ip6_address_t * ip6_prefix, u8 ip6_prefix_len,
  		     ip4_address_t * ip4_prefix, u8 ip4_prefix_len,
  		     ip4_address_t * ip4_src, u16 mtu, bool security_check,
  		     u32 fib_index, u32 * sixrd_tunnel_index)
  {
    sixrd_main_t *sm = &sixrd_main;
    sixrd_tunnel_t *t;
  
    if (fib_index == ~0)
      return VNET_API_ERROR_NO_SUCH_FIB;
  
    if ((ip6_prefix_len + 32 - ip4_prefix_len) > 64)
      return VNET_API_ERROR_INVALID_VALUE;
  
    /* Tunnel already configured */
    if (find_tunnel (ip6_prefix))
      return VNET_API_ERROR_INVALID_VALUE;
    /* Tunnel already configured for this source */
    if (find_tunnel_by_ip4_address (ip4_src))
      return VNET_API_ERROR_INVALID_VALUE;
  
    /* Get tunnel index */
    pool_get_aligned (sm->tunnels, t, CLIB_CACHE_LINE_BYTES);
    memset (t, 0, sizeof (*t));
    t->tunnel_index = t - sm->tunnels;
  
    /* Init tunnel struct */
    t->ip4_prefix.as_u32 = ip4_prefix->as_u32;
    t->ip4_prefix_len = ip4_prefix_len;
    t->ip6_prefix = *ip6_prefix;
    t->ip6_prefix_len = ip6_prefix_len;
    t->ip4_src = *ip4_src;
    t->mtu = mtu ? mtu : SIXRD_DEFAULT_MTU;
    t->security_check = security_check;
  
    t->shift = (ip4_prefix_len < 32) ?
      64 - ip6_prefix_len - (32 - ip4_prefix_len) : 0;
  
    /* Create interface */
    u32 hw_if_index = vnet_register_interface (vnet_get_main (),
  					     sixrd_device_class.index,
  					     t->tunnel_index,
  					     sixrd_hw_interface_class.index,
  					     t->tunnel_index);
  
    /* Default the interface to up and enable IPv6 (payload) */
    vnet_hw_interface_t *hi =
      vnet_get_hw_interface (vnet_get_main (), hw_if_index);
    t->hw_if_index = hw_if_index;
    t->fib_index = fib_index;
    t->sw_if_index = hi->sw_if_index;
  
    hi->max_l3_packet_bytes[VLIB_RX] = hi->max_l3_packet_bytes[VLIB_TX] =
      t->mtu;
  
    vec_validate_init_empty (sm->tunnel_index_by_sw_if_index, hi->sw_if_index,
  			   ~0);
    sm->tunnel_index_by_sw_if_index[hi->sw_if_index] = t->tunnel_index;
  
    hash_set (sm->tunnel_by_ip, ip4_src->as_u32, t->tunnel_index);
  
    vnet_hw_interface_set_flags (vnet_get_main (), hw_if_index,
  			       VNET_HW_INTERFACE_FLAG_LINK_UP);
    vnet_sw_interface_set_flags (vnet_get_main (), hi->sw_if_index,
  			       VNET_SW_INTERFACE_FLAG_ADMIN_UP);
  
    /* Create IPv6 route/adjacency */
    fib_prefix_t pfx6 = {
      .fp_proto = FIB_PROTOCOL_IP6,
      .fp_len = t->ip6_prefix_len,
      .fp_addr = {.ip6 = t->ip6_prefix,}
      ,
    };
  
    fib_table_entry_update_one_path (fib_index, &pfx6,
  				   FIB_SOURCE_CLI, FIB_ENTRY_FLAG_ATTACHED,
  				   DPO_PROTO_IP6, &sixrd_special_nh,
  				   hi->sw_if_index,
  				   ~0, 1, NULL, FIB_ROUTE_PATH_FLAG_NONE);
  
    *sixrd_tunnel_index = hi->sw_if_index;
  
    ip4_register_protocol (IP_PROTOCOL_IPV6, ip4_sixrd_node.index);
  
    return 0;
  }
  
  /*
   * sixrd_delete_tunnel
   */
  int
  sixrd_delete_tunnel (u32 sw_if_index)
  {
    sixrd_main_t *sm = &sixrd_main;
    sixrd_tunnel_t *t = find_tunnel_by_sw_if_index (sw_if_index);
  
    if (!t)
      {
        clib_warning ("SIXRD tunnel delete: tunnel does not exist: %d",
  		    sw_if_index);
        return -1;
      }
  
    fib_prefix_t pfx6 = {
      .fp_proto = FIB_PROTOCOL_IP6,
      .fp_len = t->ip6_prefix_len,
      .fp_addr = {.ip6 = t->ip6_prefix,}
      ,
    };
    fib_table_entry_special_remove (0, &pfx6, FIB_SOURCE_CLI);
    vnet_sw_interface_set_flags (vnet_get_main (), t->sw_if_index,
  			       0 /* down */ );
  
    sm->tunnel_index_by_sw_if_index[t->sw_if_index] = ~0;
  
    hash_unset (sm->tunnel_by_ip, t->ip4_src.as_u32);
  
    vnet_delete_hw_interface (vnet_get_main (), t->hw_if_index);
  
    pool_put (sm->tunnels, t);
  
    return 0;
  }
  
  static clib_error_t *
  sixrd_add_del_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;
    ip4_address_t ip4_prefix;
    ip6_address_t ip6_prefix;
    ip4_address_t ip4_src;
    u32 ip6_prefix_len = 0, ip4_prefix_len = 0, sixrd_tunnel_index;
    u32 num_m_args = 0;
    /* Optional arguments */
    u32 mtu = 0;
    u32 fib_index = 0;
    clib_error_t *error = 0;
    bool is_add = true, security_check = false;
  
    /* 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 = false;
        if (unformat (line_input, "security-check"))
  	security_check = true;
        else
  	if (unformat
  	    (line_input, "ip6-pfx %U/%d", unformat_ip6_address, &ip6_prefix,
  	     &ip6_prefix_len))
  	num_m_args++;
        else if (unformat (line_input, "ip4-pfx %U/%d", unformat_ip4_address,
  			 &ip4_prefix, &ip4_prefix_len))
  	num_m_args++;
        else
  	if (unformat
  	    (line_input, "ip4-src %U", unformat_ip4_address, &ip4_src))
  	num_m_args++;
        else if (unformat (line_input, "mtu %d", &mtu))
  	num_m_args++;
        else if (unformat (line_input, "fib-id %d", &fib_index))
  	;
        else
  	{
  	  error =
  	    clib_error_return (0, "unknown input `%U'", format_unformat_error,
  			       line_input);
  	  goto done;
  	}
      }
  
    if (num_m_args < 3)
      {
        error = clib_error_return (0, "mandatory argument(s) missing");
        goto done;
      }
    if (is_add)
      {
        int rv = sixrd_create_tunnel (&ip6_prefix, ip6_prefix_len, &ip4_prefix,
  				    ip4_prefix_len, &ip4_src, mtu,
  				    security_check,
  				    fib_index, &sixrd_tunnel_index);
        if (rv)
  	error = clib_error_return (0, "adding tunnel failed");
      }
    else
      {
        sixrd_tunnel_t *t = find_tunnel (&ip6_prefix);
        if (t)
  	{
  	  sixrd_delete_tunnel (t->sw_if_index);
  	}
      }
  
  done:
    unformat_free (line_input);
  
    return error;
  }
  
  /* *INDENT-OFF* */
  VLIB_CLI_COMMAND (sixrd_add_del_tunnel_command, static) =
  {
    .path = "create 6rd tunnel",
    .short_help = "create 6rd tunnel ip6-pfx <ip6-pfx> ip4-pfx <ip4-pfx> "
    "ip4-src <ip4-addr> [del]",
    .function = sixrd_add_del_tunnel_command_fn,
  };
  /* *INDENT-ON* */
  
  static void
  vl_api_sixrd_add_tunnel_t_handler (vl_api_sixrd_add_tunnel_t * mp)
  {
    sixrd_main_t *sm = &sixrd_main;
    vl_api_sixrd_add_tunnel_reply_t *rmp;
    u32 sixrd_tunnel_index;
  
    int rv = sixrd_create_tunnel ((ip6_address_t *) & mp->ip6_prefix,
  				mp->ip6_prefix_len,
  				(ip4_address_t *) & mp->ip4_prefix,
  				mp->ip4_prefix_len,
  				(ip4_address_t *) & mp->ip4_src,
  				ntohs (mp->mtu),
  				mp->security_check, ntohl (mp->fib_index),
  				&sixrd_tunnel_index);
  
    REPLY_MACRO2 (VL_API_SIXRD_ADD_TUNNEL_REPLY, (
  						 {
  						 rmp->sw_if_index =
  						 htonl (sixrd_tunnel_index);
  						 }));
  }
  
  static void
  vl_api_sixrd_del_tunnel_t_handler (vl_api_sixrd_del_tunnel_t * mp)
  {
    sixrd_main_t *sm = &sixrd_main;
    vl_api_sixrd_del_tunnel_reply_t *rmp;
  
    int rv = sixrd_delete_tunnel (ntohl (mp->sw_if_index));
  
    REPLY_MACRO (VL_API_SIXRD_DEL_TUNNEL_REPLY);
  }
  
  /* List of message types that this plugin understands */
  
  #define foreach_sixrd_plugin_api_msg		\
  _(SIXRD_ADD_TUNNEL, sixrd_add_tunnel)		\
  _(SIXRD_DEL_TUNNEL, sixrd_del_tunnel)
  
  /* *INDENT-OFF* */
  VLIB_PLUGIN_REGISTER() = {
      .version = VPP_BUILD_VER,
      .description = "IPv6 Rapid Deployment on IPv4 Infrastructure (RFC5969)",
  };
  /* *INDENT-ON* */
  
  /**
   * @brief Set up the API message handling tables.
   */
  static clib_error_t *
  sixrd_plugin_api_hookup (vlib_main_t * vm)
  {
    sixrd_main_t *sm = &sixrd_main;
  
  #define _(N, n)                                                                \
    vl_msg_api_set_handlers((VL_API_##N + sm->msg_id_base), #n,                  \
                            vl_api_##n##_t_handler, vl_noop_handler,             \
                            vl_api_##n##_t_endian, vl_api_##n##_t_print,         \
                            sizeof(vl_api_##n##_t), 1);
    foreach_sixrd_plugin_api_msg;
  #undef _
  
    return 0;
  }
  
  #define vl_msg_name_crc_list
  #include "sixrd_all_api_h.h"
  #undef vl_msg_name_crc_list
  
  static void
  setup_message_id_table (sixrd_main_t * sm, api_main_t * am)
  {
  #define _(id, n, crc)                                                          \
    vl_msg_api_add_msg_name_crc(am, #n "_" #crc, id + sm->msg_id_base);
    foreach_vl_msg_name_crc_sixrd;
  #undef _
  }
  
  static void
  sixrd_adj_delegate_adj_deleted (adj_delegate_t * aed)
  {
    sixrd_adj_delegate_t *sixrd_ad;
  
    sixrd_ad = sixrd_adj_from_base (aed);
  
    fib_entry_child_remove (sixrd_ad->sixrd_fib_entry_index,
  			  sixrd_ad->sixrd_sibling);
    fib_table_entry_delete_index (sixrd_ad->sixrd_fib_entry_index,
  				FIB_SOURCE_RR);
  
    pool_put (sixrd_adj_delegate_pool, sixrd_ad);
  }
  
  static u8 *
  sixrd_adj_delegate_format (const adj_delegate_t * aed, u8 * s)
  {
    const sixrd_adj_delegate_t *sixrd_ad;
  
    sixrd_ad = sixrd_adj_from_const_base (aed);
  
    s = format (s, "SIXRD:[fib-entry:%d]", sixrd_ad->sixrd_fib_entry_index);
  
    return (s);
  }
  
  static void
  sixrd_fib_node_last_lock_gone (fib_node_t * node)
  {
    // top of the dependency tree, locks not managed here.
  }
  
  static sixrd_adj_delegate_t *
  sixrd_adj_delegate_from_fib_node (fib_node_t * node)
  {
    return ((sixrd_adj_delegate_t *) (((char *) node) -
  				    STRUCT_OFFSET_OF (sixrd_adj_delegate_t,
  						      sixrd_node)));
  }
  
  static fib_node_back_walk_rc_t
  sixrd_fib_node_back_walk_notify (fib_node_t * node,
  				 fib_node_back_walk_ctx_t * ctx)
  {
    sixrd_adj_delegate_t *sixrd_ad;
  
    sixrd_ad = sixrd_adj_delegate_from_fib_node (node);
  
    ip6ip_tunnel_stack (sixrd_ad->adj_index, sixrd_ad->sixrd_fib_entry_index);
  
    return (FIB_NODE_BACK_WALK_CONTINUE);
  }
  
  /**
   * Function definition to get a FIB node from its index
   */
  static fib_node_t *
  sixrd_fib_node_get (fib_node_index_t index)
  {
    sixrd_adj_delegate_t *sixrd_ad;
  
    sixrd_ad = pool_elt_at_index (sixrd_adj_delegate_pool, index);
  
    return (&sixrd_ad->sixrd_node);
  }
  
  /**
   * VFT registered with the adjacency delegate
   */
  const static adj_delegate_vft_t sixrd_adj_delegate_vft = {
    .adv_adj_deleted = sixrd_adj_delegate_adj_deleted,
    .adv_format = sixrd_adj_delegate_format,
  };
  
  /**
   * VFT registered with the FIB node for the adj delegate
   */
  const static fib_node_vft_t sixrd_fib_node_vft = {
    .fnv_get = sixrd_fib_node_get,
    .fnv_last_lock = sixrd_fib_node_last_lock_gone,
    .fnv_back_walk = sixrd_fib_node_back_walk_notify,
  };
  
  static clib_error_t *
  sixrd_init (vlib_main_t * vm)
  {
    sixrd_main_t *sm = &sixrd_main;
    clib_error_t *error = 0;
    u8 *name;
  
    name = format (0, "sixrd_%08x%c", api_version, 0);
  
    sm->msg_id_base =
      vl_msg_api_get_msg_ids ((char *) name, VL_MSG_FIRST_AVAILABLE);
    vec_free (name);
    error = sixrd_plugin_api_hookup (vm);
  
    setup_message_id_table (sm, &api_main);
  
    sixrd_adj_delegate_type =
      adj_delegate_register_new_type (&sixrd_adj_delegate_vft);
    sixrd_fib_node_type = fib_node_register_new_type (&sixrd_fib_node_vft);
  
    return error;
  }
  
  VLIB_INIT_FUNCTION (sixrd_init);
  
  /*
   * fd.io coding-style-patch-verification: ON
   *
   * Local Variables:
   * eval: (c-set-style "gnu")
   * End:
   */
  