Add TUN device. From Max Neklyudov

2 files changed, 1256 insertions, 0 deletions

diff --git a/nuttx/drivers/net/Make.defs b/nuttx/drivers/net/Make.defs
index 7b6a71f52..c1bce6d6f 100644
--- a/nuttx/drivers/net/Make.defs
+++ b/nuttx/drivers/net/Make.defs
@@ -67,6 +67,10 @@ ifeq ($(CONFIG_NET_SLIP),y)
   CSRCS += slip.c
 endif
 
+ifeq ($(CONFIG_NET_TUN),y)
+  CSRCS += tun.c
+endif
+
 ifeq ($(CONFIG_ARCH_PHY_INTERRUPT),y)
   CSRCS += phy_notify.c
 endif
diff --git a/nuttx/drivers/net/tun.c b/nuttx/drivers/net/tun.c
new file mode 100644
index 000000000..8da3e2b98
--- /dev/null
+++ b/nuttx/drivers/net/tun.c
@@ -0,0 +1,1252 @@
+/****************************************************************************
+ * drivers/net/tun.c
+ *
+ *   Copyright (C) 2015 Max Nekludov. All rights reserved.
+ *   Author: Max Nekludov <macscomp@gmail.com>
+ *
+ * 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>
+#if defined(CONFIG_NET) && defined(CONFIG_NET_TUN)
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <time.h>
+#include <string.h>
+#include <errno.h>
+#include <assert.h>
+#include <fcntl.h>
+#include <debug.h>
+
+#ifndef CONFIG_DISABLE_POLL
+#  include <poll.h>
+#endif
+
+#include <arpa/inet.h>
+
+#include <nuttx/arch.h>
+#include <nuttx/irq.h>
+#include <nuttx/wdog.h>
+#include <nuttx/net/arp.h>
+#include <nuttx/net/netdev.h>
+
+#include <net/if.h>
+#include <nuttx/net/tun.h>
+
+#ifdef CONFIG_NET_NOINTS
+#  include <nuttx/wqueue.h>
+#endif
+
+#ifdef CONFIG_NET_PKT
+#  include <nuttx/net/pkt.h>
+#endif
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+/* If processing is not done at the interrupt level, then high priority
+ * work queue support is required.
+ */
+
+#if defined(CONFIG_NET_NOINTS) && !defined(CONFIG_SCHED_HPWORK)
+#  error High priority work queue support is required
+#endif
+
+/* CONFIG_TUN_NINTERFACES determines the number of physical interfaces
+ * that will be supported.
+ */
+
+#ifndef CONFIG_TUN_NINTERFACES
+# define CONFIG_TUN_NINTERFACES 1
+#endif
+
+/* TX poll delay = 1 seconds. CLK_TCK is the number of clock ticks per
+ * second
+ */
+
+#define TUN_WDDELAY   (1*CLK_TCK)
+#define TUN_POLLHSEC  (1*2)
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/* The tun_device_s encapsulates all state information for a single hardware
+ * interface
+ */
+
+struct tun_device_s
+{
+  bool              bifup;   /* true:ifup false:ifdown */
+  WDOG_ID           txpoll;  /* TX poll timer */
+#ifdef CONFIG_NET_NOINTS
+  struct work_s     work;    /* For deferring work to the work queue */
+#endif
+
+  FAR struct file  *filep;
+
+#ifndef CONFIG_DISABLE_POLL
+  FAR struct pollfd *poll_fds;
+#endif
+
+  bool              read_ready;
+  bool              read_wait;
+
+  uint8_t           read_buf[CONFIG_NET_TUN_MTU];
+  size_t            read_d_len;
+  uint8_t           write_buf[CONFIG_NET_TUN_MTU];
+  size_t            write_d_len;
+
+  sem_t             waitsem;
+  sem_t             read_wait_sem;
+
+  /* This holds the information visible to uIP/NuttX */
+
+  struct net_driver_s dev;     /* Interface understood by uIP */
+};
+
+struct tun_driver_s
+{
+  uint8_t free_tuns;
+  sem_t waitsem;
+};
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+static void tun_lock(FAR struct tun_device_s *priv);
+static void tun_unlock(FAR struct tun_device_s *priv);
+
+/* Common TX logic */
+
+static int  tun_transmit(FAR struct tun_device_s *priv);
+static int  tun_txpoll(struct net_driver_s *dev);
+
+/* Interrupt handling */
+
+static void tun_receive(FAR struct tun_device_s *priv);
+static void tun_txdone(FAR struct tun_device_s *priv);
+
+/* Watchdog timer expirations */
+
+static inline void tun_poll_process(FAR struct tun_device_s *priv);
+#ifdef CONFIG_NET_NOINTS
+static void tun_poll_work(FAR void *arg);
+#endif
+static void tun_poll_expiry(int argc, uint32_t arg, ...);
+
+/* NuttX callback functions */
+
+static int tun_ifup(FAR struct net_driver_s *dev);
+static int tun_ifdown(FAR struct net_driver_s *dev);
+static int tun_txavail(FAR struct net_driver_s *dev);
+#if defined(CONFIG_NET_IGMP) || defined(CONFIG_NET_ICMPv6)
+static int tun_addmac(FAR struct net_driver_s *dev, FAR const uint8_t *mac);
+#endif
+#ifdef CONFIG_NET_IGMP
+static int tun_rmmac(FAR struct net_driver_s *dev, FAR const uint8_t *mac);
+#endif
+#ifdef CONFIG_NET_ICMPv6
+static void tun_ipv6multicast(FAR struct tun_device_s *priv);
+#endif
+
+static int tun_dev_init(FAR struct tun_device_s *priv,
+                        FAR struct file *filep, FAR const char* devfmt);
+static int tun_dev_uninit(FAR struct tun_device_s *priv);
+
+/* File interface */
+
+static int tun_open(FAR struct file *filep);
+static int tun_close(FAR struct file *filep);
+static ssize_t tun_read(FAR struct file *filep, FAR char *buffer,
+                        size_t buflen);
+static ssize_t tun_write(FAR struct file *filep, FAR const char *buffer,
+                         size_t buflen);
+static int tun_ioctl(FAR struct file *filep, int cmd, unsigned long arg);
+#ifndef CONFIG_DISABLE_POLL
+static int tun_poll(FAR struct file *filep, FAR struct pollfd *fds,
+                    bool setup);
+#endif
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static struct tun_driver_s g_tun;
+static struct tun_device_s g_tun_devices[CONFIG_TUN_NINTERFACES];
+
+static const struct file_operations g_tun_file_ops =
+{
+  tun_open,     /* open */
+  tun_close,    /* close */
+  tun_read,     /* read */
+  tun_write,    /* write */
+  0,                 /* seek */
+  tun_ioctl,    /* ioctl */
+#ifndef CONFIG_DISABLE_POLL
+  tun_poll,     /* poll */
+#endif
+};
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: tundev_lock
+ ****************************************************************************/
+
+static void tundev_lock(FAR struct tun_driver_s *tun)
+{
+  /* Take the semaphore (perhaps waiting) */
+
+  while (sem_wait(&tun->waitsem) != 0)
+    {
+      /* The only case that an error should occur here is if
+       * the wait was awakened by a signal.
+       */
+
+      ASSERT(errno == EINTR);
+    }
+}
+
+/****************************************************************************
+ * Name: tundev_unlock
+ ****************************************************************************/
+
+static void tundev_unlock(FAR struct tun_driver_s *tun)
+{
+  sem_post(&tun->waitsem);
+}
+
+/****************************************************************************
+ * Name: tun_lock
+ ****************************************************************************/
+
+static void tun_lock(FAR struct tun_device_s *priv)
+{
+  /* Take the semaphore (perhaps waiting) */
+
+  while (sem_wait(&priv->waitsem) != 0)
+    {
+      /* The only case that an error should occur here is if
+       * the wait was awakened by a signal.
+       */
+
+      ASSERT(errno == EINTR);
+    }
+}
+
+/****************************************************************************
+ * Name: tun_unlock
+ ****************************************************************************/
+
+static void tun_unlock(FAR struct tun_device_s *priv)
+{
+  sem_post(&priv->waitsem);
+}
+
+/****************************************************************************
+ * Name: tun_pollnotify
+ ****************************************************************************/
+
+#ifndef CONFIG_DISABLE_POLL
+static void tun_pollnotify(FAR struct tun_device_s *priv, pollevent_t eventset)
+{
+  FAR struct pollfd *fds = priv->poll_fds;
+
+  eventset &= fds->events;
+
+  if (eventset != 0)
+    {
+      fds->revents |= eventset;
+      //fvdbg("Report events: %02x\n", fds->revents);
+      sem_post(fds->sem);
+    }
+}
+#else
+#  define uart_pollnotify(dev,event)
+#endif
+
+/****************************************************************************
+ * Function: tun_transmit
+ *
+ * Description:
+ *   Start hardware transmission.  Called either from the txdone interrupt
+ *   handling or from watchdog based polling.
+ *
+ * Parameters:
+ *   priv - Reference to the driver state structure
+ *
+ * Returned Value:
+ *   OK on success; a negated errno on failure
+ *
+ * Assumptions:
+ *   May or may not be called from an interrupt handler.  In either case,
+ *   global interrupts are disabled, either explicitly or indirectly through
+ *   interrupt handling logic.
+ *
+ ****************************************************************************/
+
+static int tun_transmit(FAR struct tun_device_s *priv)
+{
+  /* Verify that the hardware is ready to send another packet.  If we get
+   * here, then we are committed to sending a packet; Higher level logic
+   * must have assured that there is no transmission in progress.
+   */
+
+  priv->read_ready  = true;
+
+  if (priv->read_wait)
+    {
+      priv->read_wait = false;
+      sem_post(&priv->read_wait_sem);
+    }
+
+  if (priv->poll_fds)
+    {
+      tun_pollnotify(priv, POLLIN);
+    }
+
+  return OK;
+}
+
+/****************************************************************************
+ * Function: tun_txpoll
+ *
+ * Description:
+ *   The transmitter is available, check if uIP has any outgoing packets
+ *   ready to send.  This is a callback from devif_poll().  devif_poll() may
+ *   be called:
+ *
+ *   1. When the preceding TX packet send is complete,
+ *   2. When the preceding TX packet send timesout and the interface is reset
+ *   3. During normal TX polling
+ *
+ * Parameters:
+ *   dev - Reference to the NuttX driver state structure
+ *
+ * Returned Value:
+ *   OK on success; a negated errno on failure
+ *
+ * Assumptions:
+ *   May or may not be called from an interrupt handler.  In either case,
+ *   global interrupts are disabled, either explicitly or indirectly through
+ *   interrupt handling logic.
+ *
+ ****************************************************************************/
+
+static int tun_txpoll(struct net_driver_s *dev)
+{
+  FAR struct tun_device_s *priv = (FAR struct tun_device_s *)dev->d_private;
+
+  /* If the polling resulted in data that should be sent out on the network,
+   * the field d_len is set to a value > 0.
+   */
+
+  if (priv->dev.d_len > 0)
+    {
+      /* Send the packet */
+
+      tun_transmit(priv);
+
+      return 1;
+    }
+
+  /* If zero is returned, the polling will continue until all connections have
+   * been examined.
+   */
+
+  return 0;
+}
+
+/****************************************************************************
+ * Function: tun_receive
+ *
+ * Description:
+ *   An interrupt was received indicating the availability of a new RX packet
+ *
+ * Parameters:
+ *   priv - Reference to the driver state structure
+ *
+ * Returned Value:
+ *   None
+ *
+ * Assumptions:
+ *   Global interrupts are disabled by interrupt handling logic.
+ *
+ ****************************************************************************/
+
+static void tun_receive(FAR struct tun_device_s *priv)
+{
+  /* Copy the data data from the hardware to priv->dev.d_buf.  Set amount of
+   * data in priv->dev.d_len
+   */
+
+#ifdef CONFIG_NET_PKT
+  /* When packet sockets are enabled, feed the frame into the packet tap */
+
+  pkt_input(&priv->dev);
+#endif
+
+  /* We only accept IP packets of the configured type and ARP packets */
+
+#ifdef CONFIG_NET_IPv4
+    {
+      nllvdbg("IPv4 frame\n");
+
+      /* Give the IPv4 packet to the network layer */
+
+      ipv4_input(&priv->dev);
+
+      /* If the above function invocation resulted in data that should be
+       * sent out on the network, the field  d_len will set to a value > 0.
+       */
+
+      if (priv->dev.d_len > 0)
+        {
+          priv->write_d_len = priv->dev.d_len;
+        }
+      else
+        {
+          priv->write_d_len = 0;
+        }
+    }
+#endif
+
+#if 0
+#ifdef CONFIG_NET_IPv6
+  if (BUF->type == HTONS(ETHTYPE_IP6))
+    {
+      nllvdbg("Iv6 frame\n");
+
+      /* Give the IPv6 packet to the network layer */
+
+      ipv6_input(&priv->dev);
+
+      /* If the above function invocation resulted in data that should be
+        * sent out on the network, the field  d_len will set to a value > 0.
+        */
+
+      if (priv->dev.d_len > 0)
+        {
+          /* Update the Ethernet header with the correct MAC address */
+
+#ifdef CONFIG_NET_IPv4
+          if (IFF_IS_IPv4(priv->dev.d_flags))
+            {
+              arp_out(&priv->dev);
+            }
+          else
+#endif
+#ifdef CONFIG_NET_IPv6
+            {
+              neighbor_out(&priv->dev);
+            }
+#endif
+
+          /* And send the packet */
+
+          tun_transmit(priv);
+        }
+    }
+#endif
+#endif
+}
+
+/****************************************************************************
+ * Function: tun_txdone
+ *
+ * Description:
+ *   An interrupt was received indicating that the last TX packet(s) is done
+ *
+ * Parameters:
+ *   dev - Reference to the driver state structure
+ *
+ * Returned Value:
+ *   None
+ *
+ * Assumptions:
+ *   Global interrupts are disabled by the watchdog logic.
+ *
+ ****************************************************************************/
+
+static void tun_txdone(FAR struct tun_device_s *priv)
+{
+  /* Check for errors and update statistics */
+
+  /* Then poll uIP for new XMIT data */
+
+  priv->dev.d_buf = priv->read_buf;
+  (void)devif_poll(&priv->dev, tun_txpoll);
+  priv->read_d_len = priv->dev.d_len;
+}
+
+/****************************************************************************
+ * Function: tun_poll_process
+ *
+ * Description:
+ *   Perform the periodic poll.  This may be called either from watchdog
+ *   timer logic or from the worker thread, depending upon the configuration.
+ *
+ * Parameters:
+ *   priv - Reference to the driver state structure
+ *
+ * Returned Value:
+ *   None
+ *
+ * Assumptions:
+ *
+ ****************************************************************************/
+
+static inline void tun_poll_process(FAR struct tun_device_s *priv)
+{
+  /* Check if there is room in the send another TX packet.  We cannot perform
+   * the TX poll if he are unable to accept another packet for transmission.
+   */
+
+  /* If so, update TCP timing states and poll uIP for new XMIT data. Hmmm..
+   * might be bug here.  Does this mean if there is a transmit in progress,
+   * we will missing TCP time state updates?
+   */
+
+  priv->dev.d_buf = priv->read_buf;
+  (void)devif_timer(&priv->dev, tun_txpoll, TUN_POLLHSEC);
+  priv->read_d_len = priv->dev.d_len;
+
+  /* Setup the watchdog poll timer again */
+
+  (void)wd_start(priv->txpoll, TUN_WDDELAY, tun_poll_expiry, 1, priv);
+}
+
+/****************************************************************************
+ * Function: tun_poll_work
+ *
+ * Description:
+ *   Perform periodic polling from the worker thread
+ *
+ * Parameters:
+ *   arg - The argument passed when work_queue() as called.
+ *
+ * Returned Value:
+ *   OK on success
+ *
+ * Assumptions:
+ *   Ethernet interrupts are disabled
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_NET_NOINTS
+static void tun_poll_work(FAR void *arg)
+{
+  FAR struct tun_device_s *priv = (FAR struct tun_device_s *)arg;
+  net_lock_t state;
+
+  /* Perform the poll */
+
+  state = net_lock();
+  tun_poll_process(priv);
+  net_unlock(state);
+}
+#endif
+
+/****************************************************************************
+ * Function: tun_poll_expiry
+ *
+ * Description:
+ *   Periodic timer handler.  Called from the timer interrupt handler.
+ *
+ * Parameters:
+ *   argc - The number of available arguments
+ *   arg  - The first argument
+ *
+ * Returned Value:
+ *   None
+ *
+ * Assumptions:
+ *   Global interrupts are disabled by the watchdog logic.
+ *
+ ****************************************************************************/
+
+static void tun_poll_expiry(int argc, uint32_t arg, ...)
+{
+  FAR struct tun_device_s *priv = (FAR struct tun_device_s *)arg;
+
+#ifdef CONFIG_NET_NOINTS
+  /* Is our single work structure available?  It may not be if there are
+   * pending interrupt actions.
+   */
+
+  if (work_available(&priv->work))
+    {
+      /* Schedule to perform the interrupt processing on the worker thread. */
+
+      work_queue(HPWORK, &priv->work, tun_poll_work, priv, 0);
+    }
+  else
+    {
+      /* No.. Just re-start the watchdog poll timer, missing one polling
+       * cycle.
+       */
+
+      (void)wd_start(priv->txpoll, TUN_WDDELAY, tun_poll_expiry, 1, arg);
+    }
+
+#else
+  /* Process the interrupt now */
+
+  tun_poll_process(priv);
+#endif
+}
+
+/****************************************************************************
+ * Function: tun_ifup
+ *
+ * Description:
+ *   NuttX Callback: Bring up the Ethernet interface when an IP address is
+ *   provided
+ *
+ * Parameters:
+ *   dev - Reference to the NuttX driver state structure
+ *
+ * Returned Value:
+ *   None
+ *
+ * Assumptions:
+ *
+ ****************************************************************************/
+
+static int tun_ifup(struct net_driver_s *dev)
+{
+  FAR struct tun_device_s *priv = (FAR struct tun_device_s *)dev->d_private;
+
+#ifdef CONFIG_NET_IPv4
+  ndbg("Bringing up: %d.%d.%d.%d\n",
+       dev->d_ipaddr & 0xff, (dev->d_ipaddr >> 8) & 0xff,
+       (dev->d_ipaddr >> 16) & 0xff, dev->d_ipaddr >> 24);
+#endif
+#ifdef CONFIG_NET_IPv6
+  ndbg("Bringing up: %04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x\n",
+       dev->d_ipv6addr[0], dev->d_ipv6addr[1], dev->d_ipv6addr[2],
+       dev->d_ipv6addr[3], dev->d_ipv6addr[4], dev->d_ipv6addr[5],
+       dev->d_ipv6addr[6], dev->d_ipv6addr[7]);
+#endif
+
+  /* Initialize PHYs, the Ethernet interface, and setup up Ethernet interrupts */
+
+  /* Instantiate the MAC address from priv->dev.d_mac.ether_addr_octet */
+
+#ifdef CONFIG_NET_ICMPv6
+  /* Set up IPv6 multicast address filtering */
+
+  tun_ipv6multicast(priv);
+#endif
+
+  /* Set and activate a timer process */
+
+  (void)wd_start(priv->txpoll, TUN_WDDELAY, tun_poll_expiry, 1, (uint32_t)priv);
+
+  priv->bifup = true;
+  return OK;
+}
+
+/****************************************************************************
+ * Function: tun_ifdown
+ *
+ * Description:
+ *   NuttX Callback: Stop the interface.
+ *
+ * Parameters:
+ *   dev - Reference to the NuttX driver state structure
+ *
+ * Returned Value:
+ *   None
+ *
+ * Assumptions:
+ *
+ ****************************************************************************/
+
+static int tun_ifdown(struct net_driver_s *dev)
+{
+  FAR struct tun_device_s *priv = (FAR struct tun_device_s *)dev->d_private;
+
+  tun_lock(priv);
+
+  /* Cancel the TX poll timer */
+
+  wd_cancel(priv->txpoll);
+
+  /* Mark the device "down" */
+
+  priv->bifup = false;
+  tun_unlock(priv);
+  return OK;
+}
+
+/****************************************************************************
+ * Function: tun_txavail
+ *
+ * Description:
+ *   Driver callback invoked when new TX data is available.  This is a
+ *   stimulus perform an out-of-cycle poll and, thereby, reduce the TX
+ *   latency.
+ *
+ * Parameters:
+ *   dev - Reference to the NuttX driver state structure
+ *
+ * Returned Value:
+ *   None
+ *
+ * Assumptions:
+ *   Called in normal user mode
+ *
+ ****************************************************************************/
+
+static int tun_txavail(struct net_driver_s *dev)
+{
+  FAR struct tun_device_s *priv = (FAR struct tun_device_s *)dev->d_private;
+  net_lock_t state;
+
+  tun_lock(priv);
+
+  /* Check if there is room to hold another outgoing packet. */
+
+  if (priv->read_ready)
+    {
+      tun_unlock(priv);
+      return OK;
+    }
+
+  state = net_lock();
+
+  if (priv->bifup)
+    {
+      /* Poll uIP for new XMIT data */
+
+      priv->dev.d_buf = priv->read_buf;
+      (void)devif_poll(&priv->dev, tun_txpoll);
+      priv->read_d_len = priv->dev.d_len;
+    }
+
+  net_unlock(state);
+  tun_unlock(priv);
+
+  return OK;
+}
+
+/****************************************************************************
+ * Function: tun_addmac
+ *
+ * Description:
+ *   NuttX Callback: Add the specified MAC address to the hardware multicast
+ *   address filtering
+ *
+ * Parameters:
+ *   dev  - Reference to the NuttX driver state structure
+ *   mac  - The MAC address to be added
+ *
+ * Returned Value:
+ *   None
+ *
+ * Assumptions:
+ *
+ ****************************************************************************/
+
+#if defined(CONFIG_NET_IGMP) || defined(CONFIG_NET_ICMPv6)
+static int tun_addmac(struct net_driver_s *dev, FAR const uint8_t *mac)
+{
+  //FAR struct tun_device_s *priv = (FAR struct tun_device_s *)dev->d_private;
+
+  /* Add the MAC address to the hardware multicast routing table */
+
+  return OK;
+}
+#endif
+
+/****************************************************************************
+ * Function: tun_rmmac
+ *
+ * Description:
+ *   NuttX Callback: Remove the specified MAC address from the hardware multicast
+ *   address filtering
+ *
+ * Parameters:
+ *   dev  - Reference to the NuttX driver state structure
+ *   mac  - The MAC address to be removed
+ *
+ * Returned Value:
+ *   None
+ *
+ * Assumptions:
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_NET_IGMP
+static int tun_rmmac(struct net_driver_s *dev, FAR const uint8_t *mac)
+{
+  //FAR struct tun_device_s *priv = (FAR struct tun_device_s *)dev->d_private;
+
+  /* Add the MAC address to the hardware multicast routing table */
+
+  return OK;
+}
+#endif
+
+/****************************************************************************
+ * Function: tun_ipv6multicast
+ *
+ * Description:
+ *   Configure the IPv6 multicast MAC address.
+ *
+ * Parameters:
+ *   priv - A reference to the private driver state structure
+ *
+ * Returned Value:
+ *   OK on success; Negated errno on failure.
+ *
+ * Assumptions:
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_NET_ICMPv6
+static void tun_ipv6multicast(FAR struct tun_device_s *priv)
+{
+}
+#endif /* CONFIG_NET_ICMPv6 */
+
+/****************************************************************************
+ * Function: tun_dev_init
+ *
+ * Description:
+ *   Initialize the TUN device
+ *
+ * Parameters:
+ *
+ * Returned Value:
+ *   OK on success; Negated errno on failure.
+ *
+ * Assumptions:
+ *
+ ****************************************************************************/
+
+static int tun_dev_init(FAR struct tun_device_s *priv, FAR struct file *filep,
+                        FAR const char* devfmt)
+{
+  int ret;
+
+  /* Initialize the driver structure */
+
+  memset(priv, 0, sizeof(struct tun_device_s));
+  priv->dev.d_ifup    = tun_ifup;     /* I/F up (new IP address) callback */
+  priv->dev.d_ifdown  = tun_ifdown;   /* I/F down callback */
+  priv->dev.d_txavail = tun_txavail;  /* New TX data callback */
+#ifdef CONFIG_NET_IGMP
+  priv->dev.d_addmac  = tun_addmac;   /* Add multicast MAC address */
+  priv->dev.d_rmmac   = tun_rmmac;    /* Remove multicast MAC address */
+#endif
+  priv->dev.d_private = (void*)priv;   /* Used to recover private state from dev */
+
+  /* Initialize the wait semaphore */
+
+  sem_init(&priv->waitsem, 0, 1);
+  sem_init(&priv->read_wait_sem, 0, 0);
+
+  /* Create a watchdog for timing polling for and timing of transmisstions */
+
+  priv->txpoll        = wd_create();  /* Create periodic poll timer */
+
+  /* Initialize other variables */
+
+  priv->write_d_len   = 0;
+  priv->read_ready    = false;
+  priv->read_wait     = false;
+
+  /* Put the interface in the down state */
+
+  tun_ifdown(&priv->dev);
+
+  if (devfmt)
+    {
+      strncpy(priv->dev.d_ifname, devfmt, IFNAMSIZ);
+    }
+
+  /* Register the device with the OS so that socket IOCTLs can be performed */
+
+  ret = netdev_register(&priv->dev, NET_LL_TUN);
+  if (ret != OK)
+    {
+      sem_destroy(&priv->waitsem);
+      sem_destroy(&priv->read_wait_sem);
+      return ret;
+    }
+
+  priv->filep         = filep;        /* Set link to file */
+  filep->f_priv       = priv;         /* Set link to TUN device */
+
+  return ret;
+}
+
+/****************************************************************************
+ * Name: tun_dev_uninit
+ ****************************************************************************/
+
+static int tun_dev_uninit(FAR struct tun_device_s *priv)
+{
+  /* Put the interface in the down state */
+
+  tun_ifdown(&priv->dev);
+
+  /* Remove the device from the OS */
+
+  (void)netdev_unregister(&priv->dev);
+
+  sem_destroy(&priv->waitsem);
+  sem_destroy(&priv->read_wait_sem);
+
+  return OK;
+}
+
+/****************************************************************************
+ * Name: tun_open
+ ****************************************************************************/
+
+static int tun_open(FAR struct file *filep)
+{
+  filep->f_priv = 0;
+
+  return OK;
+}
+
+/****************************************************************************
+ * Name: tun_close
+ ****************************************************************************/
+
+static int tun_close(FAR struct file *filep)
+{
+  FAR struct inode *inode       = filep->f_inode;
+  FAR struct tun_driver_s *tun  = inode->i_private;
+  FAR struct tun_device_s *priv = filep->f_priv;
+  int intf;
+
+  if (!priv)
+    {
+      return OK;
+    }
+
+  intf = priv - g_tun_devices;
+  tundev_lock(tun);
+
+  tun->free_tuns |= (1 << intf);
+  (void)tun_dev_uninit(priv);
+
+  tundev_unlock(tun);
+
+  return OK;
+}
+
+/****************************************************************************
+ * Name: tun_write
+ ****************************************************************************/
+
+static ssize_t tun_write(FAR struct file *filep, FAR const char *buffer,
+                         size_t buflen)
+{
+  FAR struct tun_device_s *priv = filep->f_priv;
+  net_lock_t state;
+  ssize_t ret;
+
+  if (!priv)
+    {
+      return -EINVAL;
+    }
+
+  tun_lock(priv);
+
+  if (priv->write_d_len > 0)
+    {
+      tun_unlock(priv);
+      return -EBUSY;
+    }
+
+  state = net_lock();
+
+  if (buflen > CONFIG_NET_TUN_MTU)
+    {
+      ret = -EINVAL;
+    }
+  else
+    {
+      memcpy(priv->write_buf, buffer, buflen);
+
+      priv->dev.d_buf = priv->write_buf;
+      priv->dev.d_len = buflen;
+
+      tun_receive(priv);
+
+      ret = (ssize_t)buflen;
+    }
+
+  net_unlock(state);
+  tun_unlock(priv);
+
+  return ret;
+}
+
+/****************************************************************************
+ * Name: tun_read
+ ****************************************************************************/
+
+static ssize_t tun_read(FAR struct file *filep, FAR char *buffer,
+                        size_t buflen)
+{
+  FAR struct tun_device_s *priv = filep->f_priv;
+  net_lock_t state;
+  ssize_t ret;
+  size_t write_d_len;
+  size_t read_d_len;
+
+  if (!priv)
+    {
+      return -EINVAL;
+    }
+
+  tun_lock(priv);
+
+  /* Check if there are data to read in write buffer */
+
+  write_d_len = priv->write_d_len;
+  if (write_d_len > 0)
+    {
+      if (buflen < write_d_len)
+        {
+          ret = -EINVAL;
+          goto out;
+        }
+
+      memcpy(buffer, priv->write_buf, write_d_len);
+      ret = (ssize_t)write_d_len;
+
+      priv->write_d_len = 0;
+
+      goto out;
+    }
+
+  if (!priv->read_ready)
+    {
+      if ((filep->f_oflags & O_NONBLOCK) != 0)
+        {
+          ret = -EAGAIN;
+          goto out;
+        }
+
+      priv->read_wait = true;
+      tun_unlock(priv);
+      sem_wait(&priv->read_wait_sem);
+      tun_lock(priv);
+    }
+
+  state = net_lock();
+
+  read_d_len = priv->read_d_len;
+  if (buflen < read_d_len)
+    {
+      ret = -EINVAL;
+    }
+  else
+    {
+      memcpy(buffer, priv->read_buf, read_d_len);
+      ret = (ssize_t)read_d_len;
+    }
+
+  priv->read_ready = false;
+  tun_txdone(priv);
+
+  net_unlock(state);
+
+out:
+  tun_unlock(priv);
+
+  return ret;
+}
+
+/****************************************************************************
+ * Name: tun_poll
+ ****************************************************************************/
+
+#ifndef CONFIG_DISABLE_POLL
+int tun_poll(FAR struct file *filep, FAR struct pollfd *fds, bool setup)
+{
+  FAR struct tun_device_s *priv = filep->f_priv;
+  pollevent_t eventset;
+  int ret = OK;
+  
+  if (!priv)
+    {
+      return -EINVAL;
+    }
+
+  /* Some sanity checking */
+
+  if (!priv || !fds)
+    {
+      return -ENODEV;
+    }
+
+  tun_lock(priv);
+
+  if (setup)
+    {
+      if (priv->poll_fds)
+        {
+          ret = -EBUSY;
+          goto errout;
+        }
+
+      priv->poll_fds = fds;
+
+      eventset = 0;
+
+      eventset |= (fds->events & POLLOUT);
+
+      if (priv->read_ready)
+        {
+          eventset |= (fds->events & POLLIN);
+        }
+
+      if (eventset)
+        {
+          tun_pollnotify(priv, eventset);
+        }
+    }
+  else
+    {
+      priv->poll_fds = 0;
+    }
+
+errout:
+  tun_unlock(priv);
+
+  return ret;
+}
+#endif
+
+/****************************************************************************
+ * Name: tun_ioctl
+ ****************************************************************************/
+
+static int tun_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
+{
+  FAR struct inode *inode      = filep->f_inode;
+  FAR struct tun_driver_s *tun = inode->i_private;
+  FAR struct tun_device_s *priv = filep->f_priv;
+  int ret = OK;
+
+  if (cmd == TUNSETIFF && !priv)
+    {
+      uint8_t free_tuns;
+      int intf;
+      FAR struct ifreq *ifr = (FAR struct ifreq*)arg;
+
+      if (!ifr || ifr->ifr_flags != IFF_TUN)
+        {
+          return -EINVAL;
+        }
+
+      tundev_lock(tun);
+
+      free_tuns = tun->free_tuns;
+
+      if (free_tuns == 0)
+        {
+          tundev_unlock(tun);
+          return -ENOMEM;
+        }
+
+      for (intf = 0;
+           intf < CONFIG_TUN_NINTERFACES && !(free_tuns & 1);
+           intf++, free_tuns >>= 1);
+
+      ret = tun_dev_init(&g_tun_devices[intf], filep,
+                         *ifr->ifr_name ? ifr->ifr_name : 0);
+      if (ret != OK)
+        {
+          tundev_unlock(tun);
+          return ret;
+        }
+
+      tun->free_tuns &= ~(1 << intf);
+
+      priv = filep->f_priv;
+      strncpy(ifr->ifr_name, priv->dev.d_ifname, IFNAMSIZ);
+      lldbg("--- %s\n", priv->dev.d_ifname);
+
+      tundev_unlock(tun);
+
+      return OK;
+    }
+
+  return -EBADFD;
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Function: tun_initialize
+ *
+ * Description:
+ *   Instantiate a SLIP network interface.
+ *
+ * Parameters:
+ *
+ * Returned Value:
+ *   OK on success; Negated errno on failure.
+ *
+ * Assumptions:
+ *
+ ****************************************************************************/
+
+int tun_initialize(void)
+{
+  sem_init(&g_tun.waitsem, 0, 1);
+
+  g_tun.free_tuns = (1 << CONFIG_TUN_NINTERFACES) - 1;
+
+  (void)register_driver("/dev/tun", &g_tun_file_ops, 0644, &g_tun);
+  return OK;
+}
+
+#endif /* CONFIG_NET && CONFIG_NET_TUN */