nuttx/net/neighbor/neighbor_add.c

/****************************************************************************
 * net/neighbor/neighbor_add.c
 *
 *   Copyright (C) 2007-2009, 2015, 2017 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * A leverage of logic from uIP which also has a BSD style license
 *
 *   Copyright (c) 2006, Swedish Institute of Computer Science.  All rights
 *     reserved.
 *   Author: Adam Dunkels <adam@sics.se>
 *
 * 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.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

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

#include <net/if.h>

#include <nuttx/net/net.h>
#include <nuttx/net/ip.h>
#include <nuttx/net/neighbor.h>

#include "netdev/netdev.h"
#include "neighbor/neighbor.h"

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: neighbor_add
 *
 * Description:
 *   Add the new address association to the Neighbor Table (if it is not
 *   already there).
 *
 * Input Parameters:
 *   dev    - Driver instance associated with the MAC
 *   ipaddr - The IPv6 address of the mapping.
 *   addr   - The link layer address of the mapping
 *
 * Returned Value:
 *   None
 *
 ****************************************************************************/

void neighbor_add(FAR struct net_driver_s *dev, FAR net_ipv6addr_t ipaddr,
                  FAR uint8_t *addr)
{
  uint8_t lltype;
  clock_t oldest_time;
  int     oldest_ndx;
  int     i;

  DEBUGASSERT(dev != NULL && addr != NULL);

  /* Find the matching entry, first unused entry, or the oldest used entry.
   * The unused entry will have ne_time == 0 and should generate the oldest
   * time.  REVISIT:  Could this fail on clock wraparound?  A more explicit
   * check might be to compare ne_ipaddr with the IPv6 unspecified address.
   */

  oldest_time = g_neighbors[0].ne_time;
  oldest_ndx  = 0;
  lltype      = dev->d_lltype;

  for (i = 0; i < CONFIG_NET_IPv6_NCONF_ENTRIES; ++i)
    {
      if (g_neighbors[i].ne_addr.na_lltype == lltype &&
          net_ipv6addr_cmp(g_neighbors[i].ne_ipaddr, ipaddr))
        {
          oldest_ndx = i;
          break;
        }

      if ((int)(g_neighbors[i].ne_time - oldest_time) < 0)
        {
          oldest_ndx = i;
          oldest_time = g_neighbors[i].ne_time;
        }
    }

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

  g_neighbors[oldest_ndx].ne_time = clock_systime_ticks();
  net_ipv6addr_copy(g_neighbors[oldest_ndx].ne_ipaddr, ipaddr);

  g_neighbors[oldest_ndx].ne_addr.na_lltype = lltype;
  g_neighbors[oldest_ndx].ne_addr.na_llsize = netdev_lladdrsize(dev);

  memcpy(&g_neighbors[oldest_ndx].ne_addr.u, addr,
         g_neighbors[oldest_ndx].ne_addr.na_llsize);

  /* Dump the contents of the new entry */

  neighbor_dumpentry("Added entry", &g_neighbors[oldest_ndx]);
}