tapdrvr.c

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    int i;
    for (i = 0; i < sizeof (MACADDR); ++i)
      l_Adapter->m_MAC_Broadcast[i] = 0xFF;
  }

  //====================================
  // Initialize TAP device
  //====================================
  {
    NDIS_STATUS tap_status;
    tap_status = CreateTapDevice (&l_Adapter->m_Extension, NAME (l_Adapter));
    if (tap_status != NDIS_STATUS_SUCCESS)
      {
	AdapterFreeResources (l_Adapter);
	return tap_status;
      }
  }

  if (!AddAdapterToInstanceList (l_Adapter))
    {
      NOTE_ERROR ();
      TapDeviceFreeResources (&l_Adapter->m_Extension);
      AdapterFreeResources (l_Adapter);
      return NDIS_STATUS_RESOURCES;
    }

  l_Adapter->m_InterfaceIsRunning = TRUE;

  return NDIS_STATUS_SUCCESS;
}

VOID
AdapterHalt (IN NDIS_HANDLE p_AdapterContext)
{
  BOOLEAN status;

  TapAdapterPointer l_Adapter = (TapAdapterPointer) p_AdapterContext;

  NOTE_ERROR ();

  l_Adapter->m_InterfaceIsRunning = FALSE;

  DEBUGP (("[%s] is being halted\n", NAME (l_Adapter)));
  
  DestroyTapDevice (&l_Adapter->m_Extension);

  // Free resources
  DEBUGP (("[%s] Freeing Resources\n", NAME (l_Adapter)));
  AdapterFreeResources (l_Adapter);

  status = RemoveAdapterFromInstanceList (l_Adapter);
  DEBUGP (("[TAP] RemoveAdapterFromInstanceList returned %d\n", (int) status));

  DEBUGP (("[TAP] version [%d.%d] %s %s AdapterHalt returning\n",
	   TAP_DRIVER_MAJOR_VERSION,
	   TAP_DRIVER_MINOR_VERSION,
	   __DATE__,
	   __TIME__));
}

VOID
AdapterFreeResources (TapAdapterPointer p_Adapter)
{
  MYASSERT (!p_Adapter->m_CalledAdapterFreeResources);
  p_Adapter->m_CalledAdapterFreeResources = TRUE;

  if (p_Adapter->m_NameAnsi.Buffer)
    RtlFreeAnsiString (&p_Adapter->m_NameAnsi);
  
  if (p_Adapter->m_RegisteredAdapterShutdownHandler)
    NdisMDeregisterAdapterShutdownHandler (p_Adapter->m_MiniportAdapterHandle);

  if (p_Adapter->m_MCLockAllocated)
    NdisFreeSpinLock (&l_Adapter->m_MCLock);
}

VOID
DestroyTapDevice (TapExtensionPointer p_Extension)
{
  DEBUGP (("[%s] Destroying tap device\n", p_Extension->m_TapName));

  //======================================
  // Let clients know we are shutting down
  //======================================
  p_Extension->m_TapIsRunning = FALSE;
  p_Extension->m_TapOpens = 0;
  p_Extension->m_Halt = TRUE;

  //=====================================
  // If we are concurrently executing in
  // TapDeviceHook or AdapterTransmit,
  // give those calls time to finish.
  // Note that we must be running at IRQL
  // < DISPATCH_LEVEL in order to call
  // NdisMSleep.
  //=====================================
  NdisMSleep (500000);

  //===========================================================
  // Exhaust IRP and packet queues.  Any pending IRPs will
  // be cancelled, causing user-space to get this error
  // on overlapped reads:
  //   The I/O operation has been aborted because of either a
  //   thread exit or an application request.   (code=995)
  // It's important that user-space close the device handle
  // when this code is returned, so that when we finally
  // do a NdisMDeregisterDevice, the device reference count
  // is 0.  Otherwise the driver will not unload even if the
  // the last adapter has been halted.
  //===========================================================
  FlushQueues (p_Extension);
  NdisMSleep (500000); // give user space time to respond to IRP cancel

  TapDeviceFreeResources (p_Extension);
}

VOID
TapDeviceFreeResources (TapExtensionPointer p_Extension)
{
  MYASSERT (p_Extension);
  MYASSERT (!p_Extension->m_CalledTapDeviceFreeResources);
  p_Extension->m_CalledTapDeviceFreeResources = TRUE;

  if (p_Extension->m_PacketQueue)
    QueueFree (p_Extension->m_PacketQueue);
  if (p_Extension->m_IrpQueue)
    QueueFree (p_Extension->m_IrpQueue);

  if (p_Extension->m_CreatedUnicodeLinkName)
    RtlFreeUnicodeString (&p_Extension->m_UnicodeLinkName);

  //==========================================================
  // According to DDK docs, the device is not actually deleted
  // until its reference count falls to zero.  That means we
  // still need to gracefully fail TapDeviceHook requests
  // after this point, otherwise ugly things would happen if
  // the device was disabled (e.g. in the network connections
  // control panel) while a userspace app still held an open
  // file handle to it.
  //==========================================================
  
  if (p_Extension->m_TapDevice)
    {
      BOOLEAN status;
      status = (NdisMDeregisterDevice (p_Extension->m_TapDeviceHandle)
		== NDIS_STATUS_SUCCESS);
      DEBUGP (("[TAP] Deregistering TAP device, status=%d\n", (int)status));
    }

  if (p_Extension->m_TapName)
    MemFree (p_Extension->m_TapName, NAME_BUFFER_SIZE);
  
  if (p_Extension->m_AllocatedSpinlocks)
    NdisFreeSpinLock (&p_Extension->m_QueueLock);
}

//========================================================================
//                             Tap Device Initialization
//========================================================================

NDIS_STATUS
CreateTapDevice (TapExtensionPointer p_Extension, const char *p_Name)
{
# define SIZEOF_DISPATCH (sizeof(PDRIVER_DISPATCH) * (IRP_MJ_MAXIMUM_FUNCTION + 1))
  PDRIVER_DISPATCH *l_Dispatch = NULL;
  ANSI_STRING l_TapString, l_LinkString;
  UNICODE_STRING l_TapUnicode;
  BOOLEAN l_FreeTapUnicode = FALSE;
  NTSTATUS l_Status, l_Return = NDIS_STATUS_SUCCESS;
  const char *l_UsableName;

  DEBUGP (("[TAP] version [%d.%d] creating tap device: %s\n",
	   TAP_DRIVER_MAJOR_VERSION,
	   TAP_DRIVER_MINOR_VERSION,
	   p_Name));

  NdisZeroMemory (p_Extension, sizeof (TapExtension));

  INIT_MUTEX (&p_Extension->m_OpenCloseMutex);

  l_LinkString.Buffer = NULL;
  l_TapString.Buffer = NULL;

  l_TapString.MaximumLength = l_LinkString.MaximumLength = NAME_BUFFER_SIZE;

  //=======================================
  // Set TAP device entry points
  //=======================================

  if ((l_Dispatch = MemAlloc (SIZEOF_DISPATCH, TRUE)) == NULL)
    {
      DEBUGP (("[%s] couldn't alloc TAP dispatch table\n", p_Name));
      l_Return = NDIS_STATUS_RESOURCES;
      goto cleanup;
    }

  l_Dispatch[IRP_MJ_DEVICE_CONTROL] = TapDeviceHook;
  l_Dispatch[IRP_MJ_READ] = TapDeviceHook;
  l_Dispatch[IRP_MJ_WRITE] = TapDeviceHook;
  l_Dispatch[IRP_MJ_CREATE] = TapDeviceHook;
  l_Dispatch[IRP_MJ_CLOSE] = TapDeviceHook;

  //==================================
  // Find the beginning of the GUID
  //==================================
  l_UsableName = p_Name;
  while (*l_UsableName != '{')
    {
      if (*l_UsableName == '\0')
	{
	  DEBUGP (("[%s] couldn't find leading '{' in name\n", p_Name));
	  l_Return = NDIS_STATUS_RESOURCES;
	  goto cleanup;
	}
      ++l_UsableName;
    }

  //==================================
  // Allocate pool for TAP device name
  //==================================

  if ((p_Extension->m_TapName = l_TapString.Buffer =
       MemAlloc (NAME_BUFFER_SIZE, TRUE)) == NULL)
    {
      DEBUGP (("[%s] couldn't alloc TAP name buffer\n", p_Name));
      l_Return = NDIS_STATUS_RESOURCES;
      goto cleanup;
    }

  //================================================
  // Allocate pool for TAP symbolic link name buffer
  //================================================

  if ((l_LinkString.Buffer =
       MemAlloc (NAME_BUFFER_SIZE, TRUE)) == NULL)
    {
      DEBUGP (("[%s] couldn't alloc TAP symbolic link name buffer\n",
	       p_Name));
      l_Return = NDIS_STATUS_RESOURCES;
      goto cleanup;
    }

  //=======================================================
  // Set TAP device name
  //=======================================================

  l_Status = RtlStringCchPrintfExA
    (l_TapString.Buffer,
     l_TapString.MaximumLength,
     NULL,
     NULL,
     STRSAFE_FILL_BEHIND_NULL | STRSAFE_IGNORE_NULLS,
     "%s%s%s",
     SYSDEVICEDIR,
     l_UsableName,
     TAPSUFFIX);

  if (l_Status != STATUS_SUCCESS)
    {
      DEBUGP (("[%s] couldn't format TAP device name\n",
	       p_Name));
      l_Return = NDIS_STATUS_RESOURCES;
      goto cleanup;
    }
  l_TapString.Length = (USHORT) strlen (l_TapString.Buffer);

  DEBUGP (("TAP DEV NAME: '%s'\n", l_TapString.Buffer));

  //=======================================================
  // Set TAP link name
  //=======================================================

  l_Status = RtlStringCchPrintfExA
    (l_LinkString.Buffer,
     l_LinkString.MaximumLength,
     NULL,
     NULL,
     STRSAFE_FILL_BEHIND_NULL | STRSAFE_IGNORE_NULLS,
     "%s%s%s",
     USERDEVICEDIR,
     l_UsableName,
     TAPSUFFIX);

  if (l_Status != STATUS_SUCCESS)
    {
      DEBUGP (("[%s] couldn't format TAP device symbolic link\n",
	       p_Name));
      l_Return = NDIS_STATUS_RESOURCES;
      goto cleanup;
    }
  l_LinkString.Length = (USHORT) strlen (l_LinkString.Buffer);

  DEBUGP (("TAP LINK NAME: '%s'\n", l_LinkString.Buffer));

  //==================================================
  // Convert strings to unicode
  //==================================================
  if (RtlAnsiStringToUnicodeString (&l_TapUnicode, &l_TapString, TRUE) !=
      STATUS_SUCCESS)
    {
      DEBUGP (("[%s] couldn't alloc TAP unicode name buffer\n",
		p_Name));
      l_Return = NDIS_STATUS_RESOURCES;
      goto cleanup;
    }
  l_FreeTapUnicode = TRUE;

  if (RtlAnsiStringToUnicodeString
      (&p_Extension->m_UnicodeLinkName, &l_LinkString, TRUE)
      != STATUS_SUCCESS)
    {
      DEBUGP
	(("[%s] Couldn't allocate unicode string for symbolic link name\n",
	 p_Name));
      l_Return = NDIS_STATUS_RESOURCES;
      goto cleanup;
    }
  p_Extension->m_CreatedUnicodeLinkName = TRUE;

  //==================================================
  // Create new TAP device with symbolic
  // link and associate with adapter.
  //==================================================

  l_Status = NdisMRegisterDevice
    (g_NdisWrapperHandle,
     &l_TapUnicode,
     &p_Extension->m_UnicodeLinkName,
     l_Dispatch,
     &p_Extension->m_TapDevice,
     &p_Extension->m_TapDeviceHandle
     );

  if (l_Status != STATUS_SUCCESS)
    {
      DEBUGP (("[%s] couldn't be created\n", p_Name));
      l_Return = NDIS_STATUS_RESOURCES;
      goto cleanup;
    }

  /* Set TAP device flags */
  p_Extension->m_TapDevice->Flags |= DO_DIRECT_IO;

  //========================================================
  // Initialize Packet and IRP queues.
  //
  // The packet queue is used to buffer data which has been
  // "transmitted" by the virtual NIC, before user space
  // has had a chance to read it.
  //
  // The IRP queue is used to buffer pending I/O requests
  // from userspace, i.e. read requests on the TAP device
  // waiting for the system to "transmit" something through
  // the virtual NIC.
  //
  // Basically, packets in the packet queue are used
  // to satisfy IRP requests in the IRP queue.
  //
  // QueueLock is used to lock the packet queue used
  // for the TAP-Win32 NIC -> User Space packet flow direction.
  //
  // All accesses to packet or IRP queues should be
  // bracketed by the QueueLock spinlock,
  // in order to be SMP-safe.
  //========================================================

  NdisAllocateSpinLock (&p_Extension->m_QueueLock);
  p_Extension->m_AllocatedSpinlocks = TRUE;

  p_Extension->m_PacketQueue = QueueInit (PACKET_QUEUE_SIZE);
  p_Extension->m_IrpQueue = QueueInit (IRP_QUEUE_SIZE);

  if (!p_Extension->m_PacketQueue
      || !p_Extension->m_IrpQueue)
    {
      DEBUGP (("[%s] couldn't alloc TAP queues\n", p_Name));
      l_Return = NDIS_STATUS_RESOURCES;
      goto cleanup;
    }

  //========================
  // Finalize initialization
  //========================

  p_Extension->m_TapIsRunning = TRUE;

  DEBUGP (("[%s] successfully created TAP device [%s]\n", p_Name,
	    p_Extension->m_TapName));

 cleanup:
  if (l_FreeTapUnicode)
    RtlFreeUnicodeString (&l_TapUnicode);
  if (l_LinkString.Buffer)
    MemFree (l_LinkString.Buffer, NAME_BUFFER_SIZE);
  if (l_Dispatch)
    MemFree (l_Dispatch, SIZEOF_DISPATCH);

  if (l_Return != NDIS_STATUS_SUCCESS)
    TapDeviceFreeResources (p_Extension);

  return l_Return;
}
#undef SIZEOF_DISPATCH

//========================================================
//                      Adapter Control
//========================================================
NDIS_STATUS
AdapterReset (OUT PBOOLEAN p_AddressingReset, IN NDIS_HANDLE p_AdapterContext)
{
  TapAdapterPointer l_Adapter = (TapAdapterPointer) p_AdapterContext;
  DEBUGP (("[%s] is resetting\n", NAME (l_Adapter)));
  return NDIS_STATUS_SUCCESS;
}

NDIS_STATUS AdapterReceive
  (OUT PNDIS_PACKET p_Packet,
   OUT PUINT p_Transferred,
   IN NDIS_HANDLE p_AdapterContext,
   IN NDIS_HANDLE p_ReceiveContext,
   IN UINT p_Offset,
   IN UINT p_ToTransfer)
{
  return NDIS_STATUS_SUCCESS;
}

//==============================================================
//                  Adapter Option Query/Modification
//==============================================================
NDIS_STATUS AdapterQuery
(IN NDIS_HANDLE p_AdapterContext,
 IN NDIS_OID p_OID,
 IN PVOID p_Buffer,
 IN ULONG p_BufferLength,
 OUT PULONG p_BytesWritten, OUT PULONG p_BytesNeeded)
{
  TapAdapterPointer l_Adapter = (TapAdapterPointer) p_AdapterContext;
  TapAdapterQuery l_Query, *l_QueryPtr = &l_Query;
  NDIS_STATUS l_Status = NDIS_STATUS_SUCCESS;
  UINT l_QueryLength = 4;
  BOOLEAN lock_succeeded;

  NdisZeroMemory (&l_Query, sizeof (l_Query));

  switch (p_OID)
    {
      //===================================================================
      //                       Vendor & Driver version Info
      //===================================================================
    case OID_GEN_VENDOR_DESCRIPTION:
      l_QueryPtr = (TapAdapterQueryPointer) PRODUCT_STRING;
      l_QueryLength = strlen (PRODUCT_STRING) + 1;
      break;