incubator-nuttx/net/netdev/netdev_default.c

/****************************************************************************
 * net/netdev/netdev_default.c
 *
 * 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/netdev.h>

#include "utils/utils.h"
#include "netdev/netdev.h"

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

/****************************************************************************
 * Name: netdev_default
 *
 * Description:
 *   Return the default network device.  REVISIT:  At present this function
 *   arbitrarily returns the first UP device at the head of the device
 *   list.  Perhaps the default device should be a device name
 *   configuration option?
 *
 *   So why is this here:  It represents my current though for what to do
 *   if a socket is connected with INADDY_ANY.  In this case, I suppose we
 *   should use the IP address associated with some default device???
 *
 * Input Parameters:
 *   NULL
 *
 * Returned Value:
 *  Pointer to default network driver on success; null on failure
 *
 ****************************************************************************/

FAR struct net_driver_s *netdev_default(void)
{
  FAR struct net_driver_s *ret = NULL;
  FAR struct net_driver_s *dev;

  /* Examine each registered network device */

  net_lock();
  for (dev = g_netdevices; dev; dev = dev->flink)
    {
      /* Is the interface in the "up" state? */

      if ((dev->d_flags & IFF_UP) != 0)
        {
          /* Return a reference to the first device that we find in the UP
           * state (but not the loopback device unless it is the only
           * device).
           */

          ret = dev;
          if (dev->d_lltype != NET_LL_LOOPBACK)
            {
              break;
            }
        }
    }

  net_unlock();
  return ret;
}