nuttx/net/arp/arp_send.c

/****************************************************************************
 * net/arp/arp_send.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 <unistd.h>
#include <string.h>
#include <debug.h>

#include <netinet/in.h>
#include <net/if.h>

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

#include "netdev/netdev.h"
#include "devif/devif.h"
#include "route/route.h"
#include "arp/arp.h"

#ifdef CONFIG_NET_ARP_SEND

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Name: arp_send_terminate
 ****************************************************************************/

static void arp_send_terminate(FAR struct arp_send_s *state, int result)
{
  /* Don't allow any further call backs. */

  state->snd_sent         = true;
  state->snd_result       = (int16_t)result;
  state->snd_cb->flags    = 0;
  state->snd_cb->priv     = NULL;
  state->snd_cb->event    = NULL;

  /* Wake up the waiting thread */

  nxsem_post(&state->snd_sem);
}

/****************************************************************************
 * Name: arp_send_eventhandler
 ****************************************************************************/

static uint16_t arp_send_eventhandler(FAR struct net_driver_s *dev,
                                      FAR void *priv, uint16_t flags)
{
  FAR struct arp_send_s *state = (FAR struct arp_send_s *)priv;

  ninfo("flags: %04x sent: %d\n", flags, state->snd_sent);

  if (state)
    {
      /* Is this the device that we need to route this request? */

      if (strncmp((FAR const char *)dev->d_ifname,
                  (FAR const char *)state->snd_ifname, IFNAMSIZ) != 0)
        {
          /* No... pass on this one and wait for the device that we want */

          return flags;
        }

      /* Check if the network is still up */

      if ((flags & NETDEV_DOWN) != 0)
        {
          nerr("ERROR: Interface is down\n");
          arp_send_terminate(state, -ENETUNREACH);
          return flags;
        }

      /* Check if the outgoing packet is available. It may have been claimed
       * by a send event handler serving a different thread -OR- if the
       * output buffer currently contains unprocessed incoming data. In
       * these cases we will just have to wait for the next polling cycle.
       */

      if (dev->d_sndlen > 0 || (flags & PKT_NEWDATA) != 0)
        {
          /* Another thread has beat us sending data or the buffer is busy,
           * Check for a timeout. If not timed out, wait for the next
           * polling cycle and check again.
           */

          /* REVISIT: No timeout. Just wait for the next polling cycle */

          return flags;
        }

      /* It looks like we are good to send the data.
       *
       * Copy the packet data into the device packet buffer and send it.
       */

      arp_format(dev, state->snd_ipaddr);

      /* Make sure no ARP request overwrites this ARP request.  This
       * flag will be cleared in arp_out().
       */

      IFF_SET_NOARP(dev->d_flags);

      /* Don't allow any further call backs. */

      arp_send_terminate(state, OK);
    }

  return flags;
}

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

/****************************************************************************
 * Name: arp_send
 *
 * Description:
 *   The arp_send() call may be to send an ARP request to resolve an IP
 *   address.  This function first checks if the IP address is already in
 *   ARP table.  If so, then it returns success immediately.
 *
 *   If the requested IP address in not in the ARP table, then this function
 *   will send an ARP request, delay, then check if the IP address is now in
 *   the ARP table.  It will repeat this sequence until either (1) the IP
 *   address mapping is now in the ARP table, or (2) a configurable number
 *   of timeouts occur without receiving the ARP replay.
 *
 * Input Parameters:
 *   ipaddr   The IP address to be queried (in network order).
 *
 * Returned Value:
 *   Zero (OK) is returned on success and the IP address mapping can now be
 *   found in the ARP table.  On error a negated errno value is returned:
 *
 *     -ETIMEDOUT:    The number or retry counts has been exceed.
 *     -EHOSTUNREACH: Could not find a route to the host
 *
 * Assumptions:
 *   This function is called from the normal tasking context.
 *
 ****************************************************************************/

int arp_send(in_addr_t ipaddr)
{
  FAR struct net_driver_s *dev;
  struct arp_notify_s notify;
  struct arp_send_s state;
  int ret;

  /* First check if destination is a local broadcast. */

  if (ipaddr == INADDR_BROADCAST)
    {
      /* We don't need to send the ARP request */

      return OK;
    }

#ifdef CONFIG_NET_IGMP
  /* Check if the destination address is a multicast address
   *
   * - IPv4: multicast addresses lie in the class D group -- The address
   *   range 224.0.0.0 to 239.255.255.255 (224.0.0.0/4)
   *
   * - IPv6 multicast addresses are have the high-order octet of the
   *   addresses=0xff (ff00::/8.)
   */

  if (NTOHL(ipaddr) >= 0xe0000000 && NTOHL(ipaddr) <= 0xefffffff)
    {
      /* We don't need to send the ARP request */

      return OK;
    }
#endif

  /* Get the device that can route this request */

  dev = netdev_findby_ripv4addr(INADDR_ANY, ipaddr);
  if (!dev)
    {
      nerr("ERROR: Unreachable: %08lx\n", (unsigned long)ipaddr);
      ret = -EHOSTUNREACH;
      goto errout;
    }

  /* ARP support is only built if the Ethernet link layer is supported.
   * Continue and send the ARP request only if this device uses the
   * Ethernet link layer protocol.
   */

  if (dev->d_lltype != NET_LL_ETHERNET &&
      dev->d_lltype != NET_LL_IEEE80211)
    {
      return OK;
    }

  /* Check if the destination address is on the local network. */

  if (!net_ipv4addr_maskcmp(ipaddr, dev->d_ipaddr, dev->d_netmask))
    {
      in_addr_t dripaddr;

      /* Destination address is not on the local network */

#ifdef CONFIG_NET_ROUTE
      /* We have a routing table.. find the correct router to use in
       * this case (or, as a fall-back, use the device's default router
       * address).  We will use the router IP address instead of the
       * destination address when determining the MAC address.
       */

      netdev_ipv4_router(dev, ipaddr, &dripaddr);
#else
      /* Use the device's default router IP address instead of the
       * destination address when determining the MAC address.
       */

      net_ipv4addr_copy(dripaddr, dev->d_draddr);
#endif
      ipaddr = dripaddr;
    }

  /* The destination address is on the local network.  Check if it is
   * the sub-net broadcast address.
   */

  else if (net_ipv4addr_broadcast(ipaddr, dev->d_netmask))
    {
      /* Yes.. We don't need to send the ARP request */

      return OK;
    }

  /* Allocate resources to receive a callback.  This and the following
   * initialization is performed with the network lock because we don't
   * want anything to happen until we are ready.
   */

  net_lock();
  state.snd_cb = arp_callback_alloc(dev);
  if (!state.snd_cb)
    {
      nerr("ERROR: Failed to allocate a callback\n");
      ret = -ENOMEM;
      goto errout_with_lock;
    }

  nxsem_init(&state.snd_sem, 0, 0); /* Doesn't really fail */

  state.snd_retries   = 0;              /* No retries yet */
  state.snd_ipaddr    = ipaddr;         /* IP address to query */

  /* Remember the routing device name */

  strlcpy((FAR char *)state.snd_ifname, (FAR const char *)dev->d_ifname,
          IFNAMSIZ);

  /* Now loop, testing if the address mapping is in the ARP table and re-
   * sending the ARP request if it is not.
   */

  ret = -ETIMEDOUT; /* Assume a timeout failure */

  while (state.snd_retries < CONFIG_ARP_SEND_MAXTRIES)
    {
      /* Check if the address mapping is present in the ARP table.  This
       * is only really meaningful on the first time through the loop.
       *
       * NOTE: If the ARP table is large than this could be a performance
       * issue.
       */

      if (arp_find(ipaddr, NULL, dev) >= 0)
        {
          /* We have it!  Break out with success */

          ret = OK;
          break;
        }

      /* Set up the ARP response wait BEFORE we send the ARP request */

      arp_wait_setup(ipaddr, &notify);

      /* Arm/re-arm the callback */

      state.snd_sent      = false;
      state.snd_result    = -EBUSY;
      state.snd_cb->flags = (ARP_POLL | NETDEV_DOWN);
      state.snd_cb->priv  = (FAR void *)&state;
      state.snd_cb->event = arp_send_eventhandler;

      /* Notify the device driver that new TX data is available. */

      netdev_txnotify_dev(dev);

      /* Wait for the send to complete or an error to occur.
       * net_sem_wait will also terminate if a signal is received.
       */

      do
        {
          ret = net_sem_timedwait_uninterruptible(&state.snd_sem,
                                              CONFIG_ARP_SEND_DELAYMSEC);
          if (ret == -ETIMEDOUT)
            {
              arp_wait_cancel(&notify);
              goto timeout;
            }
        }
      while (!state.snd_sent);

      /* Check the result of the send operation */

      ret = state.snd_result;
      if (ret < 0)
        {
          /* Break out on a send failure */

          nerr("ERROR: Send failed: %d\n", ret);
          arp_wait_cancel(&notify);
          break;
        }

      /* Now wait for response to the ARP response to be received. */

      ret = arp_wait(&notify, CONFIG_ARP_SEND_DELAYMSEC);

      /* arp_wait will return OK if and only if the matching ARP response
       * is received.  Otherwise, it will return -ETIMEDOUT.
       */

      if (ret >= OK)
        {
          /* Break out if arp_wait() fails */

          break;
        }

timeout:

      /* Increment the retry count */

      state.snd_retries++;
      nerr("ERROR: arp_wait failed: %d\n", ret);
    }

  nxsem_destroy(&state.snd_sem);
  arp_callback_free(dev, state.snd_cb);
errout_with_lock:
  net_unlock();
errout:
  return ret;
}

#endif /* CONFIG_NET_ARP_SEND */