text: /*
   * Copyright (c) 2019 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/ip/ip6_link.h>
  #include <vnet/ip/ip6_ll_table.h>
  
  #include <vnet/ethernet/ethernet.h>
  #include <vnet/mfib/ip6_mfib.h>
  #include <vnet/adj/adj_mcast.h>
  
  typedef struct ip6_link_delegate_t_
  {
    u32 ild_sw_if_index;
    ip6_link_delegate_id_t ild_type;
    index_t ild_index;
  } ip6_link_delegate_t;
  
  const static ip6_link_delegate_t ip6_link_delegate_uninit = {
    .ild_sw_if_index = ~0,
  };
  
  typedef struct ip6_link_t_
  {
    /** interface ip6 is enabled on */
    u32 il_sw_if_index;
  
    /** link-local address - if unset that IP6 is disabled*/
    ip6_address_t il_ll_addr;
  
    /** list of delegates */
    ip6_link_delegate_t *il_delegates;
  
    /** multicast adjacency for this link */
    adj_index_t il_mcast_adj;
  
    /** number of references to IP6 enabled on this link */
    u32 il_locks;
  } ip6_link_t;
  
  #define FOREACH_IP6_LINK_DELEGATE(_ild, _il, body)      \
  {                                                       \
   if (NULL != _il) {                                     \
     vec_foreach (_ild, _il->il_delegates) {              \
       if (ip6_link_delegate_is_init(_ild))               \
         body;                                            \
     }                                                    \
   }                                                      \
  }
  
  #define FOREACH_IP6_LINK_DELEGATE_ID(_id) \
    for (_id = 0; _id < il_delegate_id; _id++)
  
  /** last used delegate ID */
  static ip6_link_delegate_id_t il_delegate_id;
  
  /** VFT registered per-delegate type */
  static ip6_link_delegate_vft_t *il_delegate_vfts;
  
  /** Per interface configs */
  static ip6_link_t *ip6_links;
  
  /** Randomizer */
  static u64 il_randomizer;
  
  /** Logging */
  static vlib_log_class_t ip6_link_logger;
  
  #define IP6_LINK_DBG(...)                       \
      vlib_log_debug (ip6_link_logger, __VA_ARGS__);
  
  #define IP6_LINK_INFO(...)                              \
      vlib_log_notice (ip6_link_logger, __VA_ARGS__);
  
  static bool
  ip6_link_delegate_is_init (const ip6_link_delegate_t * ild)
  {
    return (~0 != ild->ild_sw_if_index);
  }
  
  static bool
  ip6_link_is_enabled_i (const ip6_link_t * il)
  {
    return (!ip6_address_is_zero (&il->il_ll_addr));
  }
  
  static void
  ip6_link_local_address_from_mac (ip6_address_t * ip, const u8 * mac)
  {
    ip->as_u64[0] = clib_host_to_net_u64 (0xFE80000000000000ULL);
    /* Invert the "u" bit */
    ip->as_u8[8] = mac[0] ^ (1 << 1);
    ip->as_u8[9] = mac[1];
    ip->as_u8[10] = mac[2];
    ip->as_u8[11] = 0xFF;
    ip->as_u8[12] = 0xFE;
    ip->as_u8[13] = mac[3];
    ip->as_u8[14] = mac[4];
    ip->as_u8[15] = mac[5];
  }
  
  static void
  ip6_mac_address_from_link_local (u8 * mac, const ip6_address_t * ip)
  {
    /* Invert the previously inverted "u" bit */
    mac[0] = ip->as_u8[8] ^ (1 << 1);
    mac[1] = ip->as_u8[9];
    mac[2] = ip->as_u8[10];
    mac[3] = ip->as_u8[13];
    mac[4] = ip->as_u8[14];
    mac[5] = ip->as_u8[15];
  }
  
  static ip6_link_t *
  ip6_link_get (u32 sw_if_index)
  {
    ip6_link_t *il;
  
    if (sw_if_index >= vec_len (ip6_links))
      return (NULL);
  
    il = &ip6_links[sw_if_index];
  
    if (!ip6_link_is_enabled_i (il))
      return (NULL);
  
    return (il);
  }
  
  bool
  ip6_link_is_enabled (u32 sw_if_index)
  {
    return (NULL != ip6_link_get (sw_if_index));
  }
  
  
  int
  ip6_link_enable (u32 sw_if_index)
  {
    ip6_link_t *il;
    int rv;
  
    il = ip6_link_get (sw_if_index);
  
    if (NULL == il)
      {
        const vnet_sw_interface_t *sw, *sw_sup;
        const ethernet_interface_t *eth;
        vnet_main_t *vnm;
  
        vnm = vnet_get_main ();
  
        IP6_LINK_INFO ("enable: %U",
  		     format_vnet_sw_if_index_name, vnm, sw_if_index);
  
        sw_sup = vnet_get_sup_sw_interface (vnm, sw_if_index);
        if (sw_sup->type != VNET_SW_INTERFACE_TYPE_HARDWARE)
  	{
  	  rv = VNET_API_ERROR_UNSUPPORTED;
  	  goto out;
  	}
  
        eth = ethernet_get_interface (&ethernet_main, sw_sup->hw_if_index);
  
        if (NULL == eth)
  	{
  	  rv = VNET_API_ERROR_UNSUPPORTED;
  	  goto out;
  	}
  
        vec_validate (ip6_links, sw_if_index);
  
        il = &ip6_links[sw_if_index];
        il->il_locks = 1;
        il->il_sw_if_index = sw_if_index;
  
        sw = vnet_get_sup_sw_interface (vnm, sw_if_index);
  
        if (sw->type == VNET_SW_INTERFACE_TYPE_SUB ||
  	  sw->type == VNET_SW_INTERFACE_TYPE_PIPE ||
  	  sw->type == VNET_SW_INTERFACE_TYPE_P2P)
  	{
  	  il->il_ll_addr.as_u64[0] =
  	    clib_host_to_net_u64 (0xFE80000000000000ULL);
  
  	  /* make up an interface id */
  	  il->il_ll_addr.as_u64[1] = random_u64 (&il_randomizer);
  
  	  /* clear u bit */
  	  il->il_ll_addr.as_u8[8] &= 0xfd;
  	}
        else
  	{
  	  ip6_link_local_address_from_mac (&il->il_ll_addr, eth->address);
  	}
  
        {
  	ip6_ll_prefix_t ilp = {
  	  .ilp_addr = il->il_ll_addr,
  	  .ilp_sw_if_index = sw_if_index,
  	};
  
  	ip6_ll_table_entry_update (&ilp, FIB_ROUTE_PATH_LOCAL);
        }
  
        /* essentially "enables" ipv6 on this interface */
        ip6_mfib_interface_enable_disable (sw_if_index, 1);
        ip6_sw_interface_enable_disable (sw_if_index, 1);
  
        il->il_mcast_adj = adj_mcast_add_or_lock (FIB_PROTOCOL_IP6,
  						VNET_LINK_IP6, sw_if_index);
  
        /* inform all register clients */
        ip6_link_delegate_id_t id;
        FOREACH_IP6_LINK_DELEGATE_ID (id)
        {
  	if (NULL != il_delegate_vfts[id].ildv_enable)
  	  il_delegate_vfts[id].ildv_enable (il->il_sw_if_index);
        }
  
        rv = 0;
      }
    else
      {
        rv = VNET_API_ERROR_VALUE_EXIST;
      }
  
  out:
    return (rv);
  }
  
  static void
  ip6_link_delegate_flush (ip6_link_t * il)
  {
    ip6_link_delegate_t *ild;
  
    /* *INDENT-OFF* */
    FOREACH_IP6_LINK_DELEGATE (ild, il,
    ({
      il_delegate_vfts[ild->ild_type].ildv_disable(ild->ild_index);
    }));
    /* *INDENT-ON* */
  
    vec_free (il->il_delegates);
    il->il_delegates = NULL;
  }
  
  static void
  ip6_link_last_lock_gone (ip6_link_t * il)
  {
    ip6_ll_prefix_t ilp = {
      .ilp_addr = il->il_ll_addr,
      .ilp_sw_if_index = il->il_sw_if_index,
    };
  
    IP6_LINK_INFO ("last-lock: %U",
  		 format_vnet_sw_if_index_name,
  		 vnet_get_main (), il->il_sw_if_index);
  
    ip6_link_delegate_flush (il);
    ip6_ll_table_entry_delete (&ilp);
  
    ip6_mfib_interface_enable_disable (il->il_sw_if_index, 0);
    ip6_sw_interface_enable_disable (il->il_sw_if_index, 0);
  
    ip6_address_set_zero (&il->il_ll_addr);
    adj_unlock (il->il_mcast_adj);
    il->il_mcast_adj = ADJ_INDEX_INVALID;
  }
  
  static void
  ip6_link_unlock (ip6_link_t * il)
  {
    if (NULL == il)
      return;
  
    il->il_locks--;
  
    if (0 == il->il_locks)
      ip6_link_last_lock_gone (il);
  }
  
  int
  ip6_link_disable (u32 sw_if_index)
  {
    ip6_link_t *il;
  
    il = ip6_link_get (sw_if_index);
  
    if (NULL == il)
      return (VNET_API_ERROR_IP6_NOT_ENABLED);
  
    IP6_LINK_INFO ("disable: %U",
  		 format_vnet_sw_if_index_name, vnet_get_main (), sw_if_index);
  
    ip6_link_unlock (il);
  
    return (0);
  }
  
  const ip6_address_t *
  ip6_get_link_local_address (u32 sw_if_index)
  {
    const ip6_link_t *il;
  
    vec_validate (ip6_links, sw_if_index);
  
    il = &ip6_links[sw_if_index];
  
    return (&il->il_ll_addr);
  }
  
  adj_index_t
  ip6_link_get_mcast_adj (u32 sw_if_index)
  {
    const ip6_link_t *il;
  
    il = &ip6_links[sw_if_index];
  
    return (il->il_mcast_adj);
  }
  
  int
  ip6_src_address_for_packet (u32 sw_if_index,
  			    const ip6_address_t * dst, ip6_address_t * src)
  {
    ip_lookup_main_t *lm;
  
    lm = &ip6_main.lookup_main;
  
    if (ip6_address_is_link_local_unicast (dst))
      {
        ip6_address_copy (src, ip6_get_link_local_address (sw_if_index));
  
        return (!0);
      }
    else
      {
        u32 if_add_index =
  	lm->if_address_pool_index_by_sw_if_index[sw_if_index];
        if (PREDICT_TRUE (if_add_index != ~0))
  	{
  	  ip_interface_address_t *if_add =
  	    pool_elt_at_index (lm->if_address_pool, if_add_index);
  	  ip6_address_t *if_ip =
  	    ip_interface_address_get_address (lm, if_add);
  	  *src = *if_ip;
  	  return (!0);
  	}
      }
  
    src->as_u64[0] = 0;
    src->as_u64[1] = 0;
  
    return (0);
  }
  
  int
  ip6_set_link_local_address (u32 sw_if_index, const ip6_address_t * address)
  {
    ip6_link_delegate_t *ild;
    ip6_link_t *il;
  
    il = ip6_link_get (sw_if_index);
  
    if (NULL == il)
      return (VNET_API_ERROR_IP6_NOT_ENABLED);
  
    ip6_ll_prefix_t ilp = {
      .ilp_addr = il->il_ll_addr,
      .ilp_sw_if_index = sw_if_index,
    };
  
    IP6_LINK_INFO ("set-ll: %U -> %U",
  		 format_vnet_sw_if_index_name, vnet_get_main (), sw_if_index,
  		 format_ip6_address, address);
  
    ip6_ll_table_entry_delete (&ilp);
    ip6_address_copy (&il->il_ll_addr, address);
    ip6_address_copy (&ilp.ilp_addr, address);
    ip6_ll_table_entry_update (&ilp, FIB_ROUTE_PATH_LOCAL);
  
    /* *INDENT-OFF* */
    FOREACH_IP6_LINK_DELEGATE (ild, il,
    ({
      if (NULL != il_delegate_vfts[ild->ild_type].ildv_ll_change)
        il_delegate_vfts[ild->ild_type].ildv_ll_change(ild->ild_index,
                                                       &il->il_ll_addr);
    }));
    /* *INDENT-ON* */
  
    return (0);
  }
  
  ip6_link_delegate_id_t
  ip6_link_delegate_register (const ip6_link_delegate_vft_t * vft)
  {
    ip6_link_delegate_id_t rc = il_delegate_id++;
  
    ASSERT (vft->ildv_disable);
  
    vec_validate (il_delegate_vfts, rc);
  
    il_delegate_vfts[rc] = *vft;
  
    return (rc);
  }
  
  index_t
  ip6_link_delegate_get (u32 sw_if_index, ip6_link_delegate_id_t id)
  {
    ip6_link_t *il;
  
    il = ip6_link_get (sw_if_index);
  
    if (NULL == il)
      return (INDEX_INVALID);
  
    vec_validate_init_empty (il->il_delegates, id, ip6_link_delegate_uninit);
  
    if (!ip6_link_delegate_is_init (&il->il_delegates[id]))
      return (INDEX_INVALID);
  
    return (il->il_delegates[id].ild_index);
  }
  
  bool
  ip6_link_delegate_update (u32 sw_if_index,
  			  ip6_link_delegate_id_t id, index_t ii)
  {
    ip6_link_t *il;
  
    il = ip6_link_get (sw_if_index);
  
    if (NULL == il)
      return (false);
  
    vec_validate_init_empty (il->il_delegates, id, ip6_link_delegate_uninit);
  
    il->il_delegates[id].ild_sw_if_index = sw_if_index;
    il->il_delegates[id].ild_type = id;
    il->il_delegates[id].ild_index = ii;
  
    return (true);
  }
  
  void
  ip6_link_delegate_remove (u32 sw_if_index,
  			  ip6_link_delegate_id_t id, index_t ii)
  {
    ip6_link_t *il;
  
    il = ip6_link_get (sw_if_index);
  
    if (NULL != il)
      {
        if (vec_len (il->il_delegates) > id)
  	{
  	  clib_memcpy (&il->il_delegates[id],
  		       &ip6_link_delegate_uninit,
  		       sizeof (il->il_delegates[0]));
  	}
      }
  }
  
  static void
  ip6_link_add_del_address (ip6_main_t * im,
  			  uword opaque,
  			  u32 sw_if_index,
  			  ip6_address_t * address,
  			  u32 address_length,
  			  u32 if_address_index, u32 is_delete)
  {
    const ip6_link_delegate_t *ild;
    ip6_link_t *il;
  
    if (ip6_address_is_link_local_unicast (address))
      // only interested in global addresses here
      return;
  
    IP6_LINK_INFO ("addr-%s: %U -> %U",
  		 (is_delete ? "del" : "add"),
  		 format_vnet_sw_if_index_name, vnet_get_main (), sw_if_index,
  		 format_ip6_address, address);
  
    il = ip6_link_get (sw_if_index);
  
    if (NULL == il)
      return;
  
    /* *INDENT-OFF* */
    FOREACH_IP6_LINK_DELEGATE (ild, il,
    ({
        if (is_delete)
          {
            if (NULL != il_delegate_vfts[ild->ild_type].ildv_addr_del)
              il_delegate_vfts[ild->ild_type].ildv_addr_del(ild->ild_index,
                                                            address, address_length);
          }
        else
          {
            if (NULL != il_delegate_vfts[ild->ild_type].ildv_addr_add)
              il_delegate_vfts[ild->ild_type].ildv_addr_add(ild->ild_index,
                                                            address, address_length);
          }
    }));
    /* *INDENT-ON* */
  }
  
  static clib_error_t *
  ip6_link_interface_add_del (vnet_main_t * vnm, u32 sw_if_index, u32 is_add)
  {
    if (!is_add)
      {
        ip6_link_t *il;
  
        il = ip6_link_get (sw_if_index);
  
        IP6_LINK_DBG ("link-del: %U",
  		    format_vnet_sw_if_index_name, vnet_get_main (),
  		    sw_if_index);
  
        if (NULL != il)
  	/* force cleanup */
  	ip6_link_last_lock_gone (il);
      }
  
    return (NULL);
  }
  
  VNET_SW_INTERFACE_ADD_DEL_FUNCTION (ip6_link_interface_add_del);
  
  static clib_error_t *
  ip6_link_init (vlib_main_t * vm)
  {
    il_randomizer = clib_cpu_time_now ();
    ip6_link_logger = vlib_log_register_class ("ip6", "link");
  
    {
      ip6_add_del_interface_address_callback_t cb = {
        .function = ip6_link_add_del_address,
      };
      vec_add1 (ip6_main.add_del_interface_address_callbacks, cb);
    }
    return (NULL);
  }
  
  VLIB_INIT_FUNCTION (ip6_link_init);
  
  
  static clib_error_t *
  test_ip6_link_command_fn (vlib_main_t * vm,
  			  unformat_input_t * input, vlib_cli_command_t * cmd)
  {
    u8 mac[6];
    ip6_address_t _a, *a = &_a;
  
    if (unformat (input, "%U", unformat_ethernet_address, mac))
      {
        ip6_link_local_address_from_mac (a, mac);
        vlib_cli_output (vm, "Link local address: %U", format_ip6_address, a);
        ip6_mac_address_from_link_local (mac, a);
        vlib_cli_output (vm, "Original MAC address: %U",
  		       format_ethernet_address, mac);
      }
  
    return 0;
  }
  
  /*?
   * This command converts the given MAC Address into an IPv6 link-local
   * address.
   *
   * @cliexpar
   * Example of how to create an IPv6 link-local address:
   * @cliexstart{test ip6 link 16:d9:e0:91:79:86}
   * Link local address: fe80::14d9:e0ff:fe91:7986
   * Original MAC address: 16:d9:e0:91:79:86
   * @cliexend
  ?*/
  /* *INDENT-OFF* */
  VLIB_CLI_COMMAND (test_link_command, static) =
  {
    .path = "test ip6 link",
    .function = test_ip6_link_command_fn,
    .short_help = "test ip6 link <mac-address>",
  };
  /* *INDENT-ON* */
  
  static u8 *
  ip6_print_addrs (u8 * s, u32 * addrs)
  {
    ip_lookup_main_t *lm = &ip6_main.lookup_main;
    u32 i;
  
    for (i = 0; i < vec_len (addrs); i++)
      {
        ip_interface_address_t *a =
  	pool_elt_at_index (lm->if_address_pool, addrs[i]);
        ip6_address_t *address = ip_interface_address_get_address (lm, a);
  
        s = format (s, "%U%U/%d\n",
  		  format_white_space, 4,
  		  format_ip6_address, address, a->address_length);
      }
  
    return (s);
  }
  
  static u8 *
  format_ip6_link (u8 * s, va_list * arg)
  {
    const ip6_link_t *il = va_arg (*arg, ip6_link_t *);
    ip_lookup_main_t *lm = &ip6_main.lookup_main;
    vnet_main_t *vnm = vnet_get_main ();
  
    if (!ip6_link_is_enabled_i (il))
      return (s);
  
    s = format (s, "%U is admin %s\n",
  	      format_vnet_sw_interface_name, vnm,
  	      vnet_get_sw_interface (vnm, il->il_sw_if_index),
  	      (vnet_sw_interface_is_admin_up (vnm, il->il_sw_if_index) ?
  	       "up" : "down"));
  
    u32 ai;
    u32 *link_scope = 0, *global_scope = 0;
    u32 *local_scope = 0, *unknown_scope = 0;
    ip_interface_address_t *a;
    const ip6_link_delegate_t *ild;
  
    vec_validate_init_empty (lm->if_address_pool_index_by_sw_if_index,
  			   il->il_sw_if_index, ~0);
    ai = lm->if_address_pool_index_by_sw_if_index[il->il_sw_if_index];
  
    while (ai != (u32) ~ 0)
      {
        a = pool_elt_at_index (lm->if_address_pool, ai);
        ip6_address_t *address = ip_interface_address_get_address (lm, a);
  
        if (ip6_address_is_link_local_unicast (address))
  	vec_add1 (link_scope, ai);
        else if (ip6_address_is_global_unicast (address))
  	vec_add1 (global_scope, ai);
        else if (ip6_address_is_local_unicast (address))
  	vec_add1 (local_scope, ai);
        else
  	vec_add1 (unknown_scope, ai);
  
        ai = a->next_this_sw_interface;
      }
  
    if (vec_len (link_scope))
      {
        s = format (s, "%ULink-local address(es):\n", format_white_space, 2);
        s = ip6_print_addrs (s, link_scope);
        vec_free (link_scope);
      }
  
    if (vec_len (local_scope))
      {
        s = format (s, "%ULocal unicast address(es):\n", format_white_space, 2);
        s = ip6_print_addrs (s, local_scope);
        vec_free (local_scope);
      }
  
    if (vec_len (global_scope))
      {
        s = format (s, "%UGlobal unicast address(es):\n",
  		  format_white_space, 2);
        s = ip6_print_addrs (s, global_scope);
        vec_free (global_scope);
      }
  
    if (vec_len (unknown_scope))
      {
        s = format (s, "%UOther-scope address(es):\n", format_white_space, 2);
        s = ip6_print_addrs (s, unknown_scope);
        vec_free (unknown_scope);
      }
  
    s = format (s, "%ULink-local address(es):\n", format_white_space, 2);
    s = format (s, "%U%U\n",
  	      format_white_space, 4, format_ip6_address, &il->il_ll_addr);
  
    /* *INDENT-OFF* */
    FOREACH_IP6_LINK_DELEGATE(ild, il,
    ({
      s = format (s, "%U", il_delegate_vfts[ild->ild_type].ildv_format,
                       ild->ild_index, 2);
    }));
    /* *INDENT-ON* */
  
    return (s);
  }
  
  static clib_error_t *
  ip6_link_show (vlib_main_t * vm,
  	       unformat_input_t * input, vlib_cli_command_t * cmd)
  {
    const ip6_link_t *il;
    vnet_main_t *vnm;
    u32 sw_if_index;
  
    vnm = vnet_get_main ();
    sw_if_index = ~0;
  
    if (unformat_user (input, unformat_vnet_sw_interface, vnm, &sw_if_index))
      {
        il = ip6_link_get (sw_if_index);
  
        if (NULL == il)
  	{
  	  vlib_cli_output (vm, "IP6 disabled");
  	  return (NULL);
  	}
        else
  	vlib_cli_output (vm, "%U", format_ip6_link, il);
      }
    else
      {
        vec_foreach (il, ip6_links)
  	vlib_cli_output (vm, "%U", format_ip6_link, il);
      }
  
    return (NULL);
  }
  
  /*?
   * This command is used to display various IPv6 attributes on a given
   * interface.
   *
   * @cliexpar
   * Example of how to display IPv6 settings:
   * @cliexstart{show ip6 interface GigabitEthernet2/0/0}
   * GigabitEthernet2/0/0 is admin up
   *         Link-local address(es):
   *                 fe80::ab8/64
   *         Joined group address(es):
   *                 ff02::1
   *                 ff02::2
   *                 ff02::16
   *                 ff02::1:ff00:ab8
   *         Advertised Prefixes:
   *                 prefix fe80::fe:28ff:fe9c:75b3,  length 64
   *         MTU is 1500
   *         ICMP error messages are unlimited
   *         ICMP redirects are disabled
   *         ICMP unreachables are not sent
   *         ND DAD is disabled
   *         ND advertised reachable time is 0
   *         ND advertised retransmit interval is 0 (msec)
   *         ND router advertisements are sent every 200 seconds (min interval is 150)
   *         ND router advertisements live for 600 seconds
   *         Hosts use stateless autoconfig for addresses
   *         ND router advertisements sent 19336
   *         ND router solicitations received 0
   *         ND router solicitations dropped 0
   * @cliexend
   * Example of output if IPv6 is not enabled on the interface:
   * @cliexstart{show ip6 interface GigabitEthernet2/0/0}
   * show ip6 interface: IPv6 not enabled on interface
   * @cliexend
  ?*/
  /* *INDENT-OFF* */
  VLIB_CLI_COMMAND (ip6_link_show_command, static) =
  {
    .path = "show ip6 interface",
    .function = ip6_link_show,
    .short_help = "show ip6 interface <interface>",
  };
  /* *INDENT-ON* */
  
  static clib_error_t *
  enable_ip6_interface_cmd (vlib_main_t * vm,
  			  unformat_input_t * input, vlib_cli_command_t * cmd)
  {
    vnet_main_t *vnm = vnet_get_main ();
    clib_error_t *error = NULL;
    u32 sw_if_index;
  
    sw_if_index = ~0;
  
    if (unformat_user (input, unformat_vnet_sw_interface, vnm, &sw_if_index))
      {
        if (ip6_link_enable (sw_if_index))
  	error = clib_error_return (0, "Failed\n");
      }
    else
      {
        error = clib_error_return (0, "unknown interface\n'",
  				 format_unformat_error, input);
  
      }
    return error;
  }
  
  /*?
   * This command is used to enable IPv6 on a given interface.
   *
   * @cliexpar
   * Example of how enable IPv6 on a given interface:
   * @cliexcmd{enable ip6 interface GigabitEthernet2/0/0}
  ?*/
  /* *INDENT-OFF* */
  VLIB_CLI_COMMAND (enable_ip6_interface_command, static) =
  {
    .path = "enable ip6 interface",
    .function = enable_ip6_interface_cmd,
    .short_help = "enable ip6 interface <interface>",
  };
  /* *INDENT-ON* */
  
  static clib_error_t *
  disable_ip6_interface_cmd (vlib_main_t * vm,
  			   unformat_input_t * input, vlib_cli_command_t * cmd)
  {
    vnet_main_t *vnm = vnet_get_main ();
    clib_error_t *error = NULL;
    u32 sw_if_index;
  
    sw_if_index = ~0;
  
    if (unformat_user (input, unformat_vnet_sw_interface, vnm, &sw_if_index))
      {
        if (ip6_link_disable (sw_if_index))
  	error = clib_error_return (0, "Failed\n");
      }
    else
      {
        error = clib_error_return (0, "unknown interface\n'",
  				 format_unformat_error, input);
  
      }
    return error;
  }
  
  /*?
   * This command is used to disable IPv6 on a given interface.
   *
   * @cliexpar
   * Example of how disable IPv6 on a given interface:
   * @cliexcmd{disable ip6 interface GigabitEthernet2/0/0}
  ?*/
  /* *INDENT-OFF* */
  VLIB_CLI_COMMAND (disable_ip6_interface_command, static) =
  {
    .path = "disable ip6 interface",
    .function = disable_ip6_interface_cmd,
    .short_help = "disable ip6 interface <interface>",
  };
  /* *INDENT-ON* */
  
  /*
   * fd.io coding-style-patch-verification: ON
   *
   * Local Variables:
   * eval: (c-set-style "gnu")
   * End:
   */
  