static inline bool psock_send_addrchck(FAR struct tcp_conn_s *conn)
{
#ifdef CONFIG_NET_IPv4
#ifdef CONFIG_NET_IPv6
  if (conn->domain == PF_INET)
#endif
    {
#if !defined(CONFIG_NET_ARP_IPIN) && !defined(CONFIG_NET_ARP_SEND)
      return (arp_find(conn->u.ipv4.raddr) != NULL);
#else
      return true;
#endif
    }
#endif /* CONFIG_NET_IPv4 */

#ifdef CONFIG_NET_IPv6
#ifdef CONFIG_NET_IPv4
  else
#endif
    {
#if !defined(CONFIG_NET_ICMPv6_NEIGHBOR)
      return (neighbor_findentry(conn->u.ipv6.raddr) != NULL);
#else
      return true;
#endif
    }
#endif /* CONFIG_NET_IPv6 */
}
int icmpv6_neighbor(const net_ipv6addr_t ipaddr)
{
  FAR struct net_driver_s *dev;
  struct icmpv6_notify_s notify;
  struct timespec delay;
  struct icmpv6_neighbor_s state;
  FAR const uint16_t *lookup;
  net_lock_t save;
  int ret;

  /* First check if destination is a local broadcast or a multicast address.
   *
   * - IPv6 multicast addresses are have the high-order octet of the
   *   addresses=0xff (ff00::/8.)
   */

  if (net_ipv6addr_cmp(ipaddr, g_ipv6_allzeroaddr) ||
      (ipaddr[0] & NTOHS(0xff00)) == NTOHS(0xff00))
    {
      /* We don't need to send the Neighbor Solicitation */

      return OK;
    }

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

#ifdef CONFIG_NETDEV_MULTINIC
  dev = netdev_findby_ipv6addr(g_ipv6_allzeroaddr, ipaddr);
#else
  dev = netdev_findby_ipv6addr(ipaddr);
#endif
  if (!dev)
    {
      ndbg("ERROR: Unreachable: %08lx\n", (unsigned long)ipaddr);
      ret = -EHOSTUNREACH;
      goto errout;
    }

#ifdef CONFIG_NET_MULTILINK
  /* If we are supporting multiple network devices and using different
   * link level protocols then we can get here for other link protocols
   * as well.  Continue and send the Neighbor Solicitation request only
   * if this device uses the Ethernet data link protocol.
   *
   * REVISIT:  Other link layer protocols may require Neighbor Discovery
   * as well (but not SLIP which is the only other option at the moment).
   */

  if (dev->d_lltype != NET_LL_ETHERNET)
    {
      return OK;
    }
#endif

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

  if (net_ipv6addr_maskcmp(ipaddr, dev->d_ipv6addr, dev->d_ipv6netmask))
    {
      /* Yes.. use the input address for the lookup */

      lookup = ipaddr;
    }
  else
    {
      net_ipv6addr_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_ipv6_router(dev, ipaddr, dripaddr);
#else
      /* Use the device's default router IP address instead of the
       * destination address when determining the MAC address.
       */

      net_ipv6addr_copy(dripaddr, dev->d_ipv6draddr);
#endif

      /* Use the router address for the lookup */

      lookup = dripaddr;
    }

  /* 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.
   */

  save = net_lock();
  state.snd_cb = icmpv6_callback_alloc();
  if (!state.snd_cb)
    {
      ndbg("ERROR: Failed to allocate a cllback\n");
      ret = -ENOMEM;
      goto errout_with_lock;
    }

  /* Initialize the state structure. This is done with interrupts
   * disabled
   */

  (void)sem_init(&state.snd_sem, 0, 0);        /* Doesn't really fail */
  state.snd_retries = 0;                       /* No retries yet */
  net_ipv6addr_copy(state.snd_ipaddr, lookup); /* IP address to query */

#ifdef CONFIG_NETDEV_MULTINIC
  /* Remember the routing device name */

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

  /* Now loop, testing if the address mapping is in the Neighbor Table and
   * re-sending the Neighbor Solicitation if it is not.
   */

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

  while (state.snd_retries < CONFIG_ICMPv6_NEIGHBOR_MAXTRIES)
    {
      /* Check if the address mapping is present in the Neighbor Table.  This
       * is only really meaningful on the first time through the loop.
       *
       * NOTE: If the Neighbor Table is large than this could be a performance
       * issue.
       */

      if (neighbor_findentry(lookup) != NULL)
        {
          /* We have it!  Break out with success */

          ret = OK;
          break;
        }

      /* Set up the Neighbor Advertisement wait BEFORE we send the Neighbor
       * Solicitation.
       */

      icmpv6_wait_setup(lookup, &notify);

      /* Arm/re-arm the callback */

      state.snd_sent      = false;
      state.snd_cb->flags = ICMPv6_POLL;
      state.snd_cb->priv  = (FAR void *)&state;
      state.snd_cb->event = icmpv6_neighbor_interrupt;

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

      dev->d_txavail(dev);

      /* Wait for the send to complete or an error to occur: NOTES: (1)
       * net_lockedwait will also terminate if a signal is received, (2)
       * interrupts may be disabled! They will be re-enabled while the
       * task sleeps and automatically re-enabled when the task restarts.
       */

      do
        {
          (void)net_lockedwait(&state.snd_sem);
        }
      while (!state.snd_sent);

      /* Now wait for response to the Neighbor Advertisement to be received.
       * The optimal delay would be the work case round trip time.
       * NOTE: The network is locked.
       */

      delay.tv_sec  = CONFIG_ICMPv6_NEIGHBOR_DELAYSEC;
      delay.tv_nsec = CONFIG_ICMPv6_NEIGHBOR_DELAYNSEC;

      ret = icmpv6_wait(&notify, &delay);

      /* icmpv6_wait will return OK if and only if the matching Neighbor
       * Advertisement is received.  Otherwise, it will return -ETIMEDOUT.
       */

      if (ret == OK)
        {
          break;
        }

      /* Increment the retry count */

      state.snd_retries++;
    }

  sem_destroy(&state.snd_sem);
  icmpv6_callback_free(state.snd_cb);
errout_with_lock:
  net_unlock(save);
errout:
  return ret;
}