src/vnet/ip/ip6_link.c - fdio/vpp - Gitiles

 /*
  * 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, const ip6_address_t * link_local_addr)
 {
   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 = 0;
       il->il_sw_if_index = sw_if_index;

       sw = vnet_get_sup_sw_interface (vnm, sw_if_index);

       if (NULL != link_local_addr)
 	ip6_address_copy (&il->il_ll_addr, link_local_addr);
       else 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;
     }

   il->il_locks++;

 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_link_set_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 ip6_link_enable (sw_if_index, address);

   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, NULL))
 	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:
  */
	/*
	* 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, const ip6_address_t * link_local_addr)
	{
	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 = 0;
	il->il_sw_if_index = sw_if_index;

	sw = vnet_get_sup_sw_interface (vnm, sw_if_index);

	if (NULL != link_local_addr)
	ip6_address_copy (&il->il_ll_addr, link_local_addr);
	else 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;
	}

	il->il_locks++;

	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_link_set_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 ip6_link_enable (sw_if_index, address);

	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, NULL))
	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:
	*/