/*
 * uip_neighbor.c
 * Database of link-local neighbors, used by IPv6 code and to be used by
 * a future ARP code rewrite.
 *
 *   Author: Adam Dunkels <adam@sics.se>
 *   Copyright (c) 2006, Swedish Institute of Computer Science.
 *  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <string.h>
#include <debug.h>

#include "uip_neighbor.h"

#define MAX_TIME 128

#ifdef UIP_NEIGHBOR_CONF_ENTRIES
#define ENTRIES UIP_NEIGHBOR_CONF_ENTRIES
#else /* UIP_NEIGHBOR_CONF_ENTRIES */
#define ENTRIES 8
#endif /* UIP_NEIGHBOR_CONF_ENTRIES */

struct neighbor_entry
{
  uip_ipaddr_t ipaddr;
  struct uip_neighbor_addr addr;
  uint8_t time;
};
static struct neighbor_entry entries[ENTRIES];

void uip_neighbor_init(void)
{
  int i;

  for (i = 0; i < ENTRIES; ++i)
    {
      entries[i].time = MAX_TIME;
    }
}

void uip_neighbor_periodic(void)
{
  int i;

  for (i = 0; i < ENTRIES; ++i)
    {
      if (entries[i].time < MAX_TIME)
        {
        entries[i].time++;
        }
    }
}

void uip_neighbor_add(uip_ipaddr_t ipaddr, struct uip_neighbor_addr *addr)
{
  uint8_t oldest_time;
  int     oldest;
  int     i;

  nlldbg("Add neighbor: %02x:%02x:%02x:%02x:%02x:%02x\n",
         addr->addr.ether_addr_octet[0], addr->addr.ether_addr_octet[1],
         addr->addr.ether_addr_octet[2], addr->addr.ether_addr_octet[3],
         addr->addr.ether_addr_octet[4], addr->addr.ether_addr_octet[5]);

  /* Find the first unused entry or the oldest used entry. */

  oldest_time = 0;
  oldest = 0;

  for (i = 0; i < ENTRIES; ++i)
    {
      if (entries[i].time == MAX_TIME)
        {
          oldest = i;
          break;
        }
      if (uip_ipaddr_cmp(entries[i].ipaddr, addr))
        {
          oldest = i;
          break;
        }
      if (entries[i].time > oldest_time)
        {
          oldest = i;
          oldest_time = entries[i].time;
        }
    }

  /* Use the oldest or first free entry (either pointed to by the
   * "oldest" variable).
   */

  entries[oldest].time = 0;
  uip_ipaddr_copy(entries[oldest].ipaddr, ipaddr);
  memcpy(&entries[oldest].addr, addr, sizeof(struct uip_neighbor_addr));
}

static struct neighbor_entry *find_entry(uip_ipaddr_t ipaddr)
{
  int i;

  for (i = 0; i < ENTRIES; ++i)
    {
      if (uip_ipaddr_cmp(entries[i].ipaddr, ipaddr))
        {
          return &entries[i];
        }
    }

  return NULL;
}

void uip_neighbor_update(uip_ipaddr_t ipaddr)
{
  struct neighbor_entry *e;

  e = find_entry(ipaddr);
  if (e != NULL)
    {
      e->time = 0;
    }
}

struct uip_neighbor_addr *uip_neighbor_lookup(uip_ipaddr_t ipaddr)
{
  struct neighbor_entry *e;

  e = find_entry(ipaddr);
  if (e != NULL)
    {
      nlldbg("Lookup neighbor: %02x:%02x:%02x:%02x:%02x:%02x\n",
             e->addr.addr.ether_addr_octet[0], e->addr.addr.ether_addr_octet[1],
             e->addr.addr.ether_addr_octet[2], e->addr.addr.ether_addr_octet[3],
             e->addr.addr.ether_addr_octet[4], e->addr.addr.ether_addr_octet[5]);

      return &e->addr;
    }

  return NULL;
}