nuttx/net/neighbor/neighbor_out.c

/****************************************************************************
 * net/neighbor/neighbor_out.c
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.  The
 * ASF licenses this file to you 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.
 *
 ****************************************************************************/

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

#include <nuttx/config.h>

#include <nuttx/net/net.h>
#include <nuttx/net/netdev.h>

#include "neighbor/neighbor.h"

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

/****************************************************************************
 * Name: neighbor_out
 *
 * Description:
 *   This function should be called before sending out an IPv6 packet. The
 *   function checks the destination IPv6 address of the IPv6 packet to see
 *   what L2 address that should be used as a destination L2 address.
 *
 *   If the destination IPv6 address is in the local network (determined
 *   by logical ANDing of netmask and our IPv6 address), the function
 *   checks the Neighbor Table to see if an entry for the destination IPv6
 *   address is found.  If so, an L2 header is pre-pended at the beginning
 *   of the packet and the function returns.
 *
 *   If no Neighbor Table entry is found for the destination IPv6 address,
 *   the packet in the d_buf is replaced by an ICMPv6 Neighbor Solicit
 *   request packet for the IPv6 address. The IPv6 packet is dropped and
 *   it is assumed that the higher level protocols (e.g., TCP) eventually
 *   will retransmit the dropped packet.
 *
 *   Upon return in either the case, a packet to be sent is present in the
 *   d_buf buffer and the d_len field holds the length of the L2 frame that
 *   should be transmitted.
 *
 ****************************************************************************/

void neighbor_out(FAR struct net_driver_s *dev)
{
  switch (dev->d_lltype)
    {
#ifdef CONFIG_NET_ETHERNET
      case NET_LL_ETHERNET:
      case NET_LL_IEEE80211:
        neighbor_ethernet_out(dev);
        break;
#endif

      default:
        break;
    }
}