nuttx/net/netdev/netdev_default.c

/****************************************************************************
 * net/netdev/netdev_default.c
 *
 *   Copyright (C) 2014-2015, 2018 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * 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 NuttX 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 COPYRIGHT HOLDERS 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
 * COPYRIGHT OWNER 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 <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;
}