libusb/os/windows_usbdk.c

/*
 * windows UsbDk backend for libusb 1.0
 * Copyright © 2014 Red Hat, Inc.

 * Authors:
 * Dmitry Fleytman <dmitry@daynix.com>
 * Pavel Gurvich <pavel@daynix.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <config.h>

#include <windows.h>
#include <stdio.h>

#include "libusbi.h"
#include "windows_usbdk.h"

#if !defined(STATUS_SUCCESS)
typedef LONG NTSTATUS;
#define STATUS_SUCCESS			((NTSTATUS)0x00000000L)
#endif

#if !defined(STATUS_CANCELLED)
#define STATUS_CANCELLED		((NTSTATUS)0xC0000120L)
#endif

#if !defined(STATUS_REQUEST_CANCELED)
#define STATUS_REQUEST_CANCELED		((NTSTATUS)0xC0000703L)
#endif

static struct {
	HMODULE module;

	USBDK_GET_DEVICES_LIST			GetDevicesList;
	USBDK_RELEASE_DEVICES_LIST		ReleaseDevicesList;
	USBDK_START_REDIRECT			StartRedirect;
	USBDK_STOP_REDIRECT			StopRedirect;
	USBDK_GET_CONFIGURATION_DESCRIPTOR	GetConfigurationDescriptor;
	USBDK_RELEASE_CONFIGURATION_DESCRIPTOR	ReleaseConfigurationDescriptor;
	USBDK_READ_PIPE				ReadPipe;
	USBDK_WRITE_PIPE			WritePipe;
	USBDK_ABORT_PIPE			AbortPipe;
	USBDK_RESET_PIPE			ResetPipe;
	USBDK_SET_ALTSETTING			SetAltsetting;
	USBDK_RESET_DEVICE			ResetDevice;
	USBDK_GET_REDIRECTOR_SYSTEM_HANDLE	GetRedirectorSystemHandle;
} usbdk_helper;

static FARPROC get_usbdk_proc_addr(struct libusb_context *ctx, LPCSTR api_name)
{
	FARPROC api_ptr = GetProcAddress(usbdk_helper.module, api_name);

	if (api_ptr == NULL)
		usbi_err(ctx, "UsbDkHelper API %s not found: %s", api_name, windows_error_str(0));

	return api_ptr;
}

static void unload_usbdk_helper_dll(void)
{
	if (usbdk_helper.module != NULL) {
		FreeLibrary(usbdk_helper.module);
		usbdk_helper.module = NULL;
	}
}

static int load_usbdk_helper_dll(struct libusb_context *ctx)
{
	usbdk_helper.module = load_system_library(ctx, "UsbDkHelper");
	if (usbdk_helper.module == NULL) {
		usbi_err(ctx, "Failed to load UsbDkHelper.dll: %s", windows_error_str(0));
		return LIBUSB_ERROR_NOT_FOUND;
	}

	usbdk_helper.GetDevicesList = (USBDK_GET_DEVICES_LIST)get_usbdk_proc_addr(ctx, "UsbDk_GetDevicesList");
	if (usbdk_helper.GetDevicesList == NULL)
		goto error_unload;

	usbdk_helper.ReleaseDevicesList = (USBDK_RELEASE_DEVICES_LIST)get_usbdk_proc_addr(ctx, "UsbDk_ReleaseDevicesList");
	if (usbdk_helper.ReleaseDevicesList == NULL)
		goto error_unload;

	usbdk_helper.StartRedirect = (USBDK_START_REDIRECT)get_usbdk_proc_addr(ctx, "UsbDk_StartRedirect");
	if (usbdk_helper.StartRedirect == NULL)
		goto error_unload;

	usbdk_helper.StopRedirect = (USBDK_STOP_REDIRECT)get_usbdk_proc_addr(ctx, "UsbDk_StopRedirect");
	if (usbdk_helper.StopRedirect == NULL)
		goto error_unload;

	usbdk_helper.GetConfigurationDescriptor = (USBDK_GET_CONFIGURATION_DESCRIPTOR)get_usbdk_proc_addr(ctx, "UsbDk_GetConfigurationDescriptor");
	if (usbdk_helper.GetConfigurationDescriptor == NULL)
		goto error_unload;

	usbdk_helper.ReleaseConfigurationDescriptor = (USBDK_RELEASE_CONFIGURATION_DESCRIPTOR)get_usbdk_proc_addr(ctx, "UsbDk_ReleaseConfigurationDescriptor");
	if (usbdk_helper.ReleaseConfigurationDescriptor == NULL)
		goto error_unload;

	usbdk_helper.ReadPipe = (USBDK_READ_PIPE)get_usbdk_proc_addr(ctx, "UsbDk_ReadPipe");
	if (usbdk_helper.ReadPipe == NULL)
		goto error_unload;

	usbdk_helper.WritePipe = (USBDK_WRITE_PIPE)get_usbdk_proc_addr(ctx, "UsbDk_WritePipe");
	if (usbdk_helper.WritePipe == NULL)
		goto error_unload;

	usbdk_helper.AbortPipe = (USBDK_ABORT_PIPE)get_usbdk_proc_addr(ctx, "UsbDk_AbortPipe");
	if (usbdk_helper.AbortPipe == NULL)
		goto error_unload;

	usbdk_helper.ResetPipe = (USBDK_RESET_PIPE)get_usbdk_proc_addr(ctx, "UsbDk_ResetPipe");
	if (usbdk_helper.ResetPipe == NULL)
		goto error_unload;

	usbdk_helper.SetAltsetting = (USBDK_SET_ALTSETTING)get_usbdk_proc_addr(ctx, "UsbDk_SetAltsetting");
	if (usbdk_helper.SetAltsetting == NULL)
		goto error_unload;

	usbdk_helper.ResetDevice = (USBDK_RESET_DEVICE)get_usbdk_proc_addr(ctx, "UsbDk_ResetDevice");
	if (usbdk_helper.ResetDevice == NULL)
		goto error_unload;

	usbdk_helper.GetRedirectorSystemHandle = (USBDK_GET_REDIRECTOR_SYSTEM_HANDLE)get_usbdk_proc_addr(ctx, "UsbDk_GetRedirectorSystemHandle");
	if (usbdk_helper.GetRedirectorSystemHandle == NULL)
		goto error_unload;

	return LIBUSB_SUCCESS;

error_unload:
	FreeLibrary(usbdk_helper.module);
	usbdk_helper.module = NULL;
	return LIBUSB_ERROR_NOT_FOUND;
}

typedef SC_HANDLE (WINAPI *POPENSCMANAGERA)(LPCSTR, LPCSTR, DWORD);
typedef SC_HANDLE (WINAPI *POPENSERVICEA)(SC_HANDLE, LPCSTR, DWORD);
typedef BOOL (WINAPI *PCLOSESERVICEHANDLE)(SC_HANDLE);

static int usbdk_init(struct libusb_context *ctx)
{
	POPENSCMANAGERA pOpenSCManagerA;
	POPENSERVICEA pOpenServiceA;
	PCLOSESERVICEHANDLE pCloseServiceHandle;
	SC_HANDLE managerHandle;
	SC_HANDLE serviceHandle;
	HMODULE h;

	h = load_system_library(ctx, "Advapi32");
	if (h == NULL) {
		usbi_warn(ctx, "failed to open Advapi32\n");
		return LIBUSB_ERROR_OTHER;
	}

	pOpenSCManagerA = (POPENSCMANAGERA)GetProcAddress(h, "OpenSCManagerA");
	if (pOpenSCManagerA == NULL) {
		usbi_warn(ctx, "failed to find %s in Advapi32\n", "OpenSCManagerA");
		goto error_free_library;
	}
	pOpenServiceA = (POPENSERVICEA)GetProcAddress(h, "OpenServiceA");
	if (pOpenServiceA == NULL) {
		usbi_warn(ctx, "failed to find %s in Advapi32\n", "OpenServiceA");
		goto error_free_library;
	}
	pCloseServiceHandle = (PCLOSESERVICEHANDLE)GetProcAddress(h, "CloseServiceHandle");
	if (pCloseServiceHandle == NULL) {
		usbi_warn(ctx, "failed to find %s in Advapi32\n", "CloseServiceHandle");
		goto error_free_library;
	}

	managerHandle = pOpenSCManagerA(NULL, NULL, SC_MANAGER_CONNECT);
	if (managerHandle == NULL) {
		usbi_warn(ctx, "failed to open service control manager: %s", windows_error_str(0));
		goto error_free_library;
	}

	serviceHandle = pOpenServiceA(managerHandle, "UsbDk", GENERIC_READ);
	pCloseServiceHandle(managerHandle);

	if (serviceHandle == NULL) {
		if (GetLastError() != ERROR_SERVICE_DOES_NOT_EXIST)
			usbi_warn(ctx, "failed to open UsbDk service: %s", windows_error_str(0));
		FreeLibrary(h);
		return LIBUSB_ERROR_NOT_FOUND;
	}

	pCloseServiceHandle(serviceHandle);
	FreeLibrary(h);

	return load_usbdk_helper_dll(ctx);

error_free_library:
	FreeLibrary(h);
	return LIBUSB_ERROR_OTHER;
}

static void usbdk_exit(struct libusb_context *ctx)
{
	UNUSED(ctx);
	unload_usbdk_helper_dll();
}

static int usbdk_get_session_id_for_device(struct libusb_context *ctx,
	PUSB_DK_DEVICE_ID id, unsigned long *session_id)
{
	char dev_identity[ARRAYSIZE(id->DeviceID) + ARRAYSIZE(id->InstanceID) + 1];

	if (snprintf(dev_identity, sizeof(dev_identity), "%S%S", id->DeviceID, id->InstanceID) == -1) {
		usbi_warn(ctx, "cannot form device identity");
		return LIBUSB_ERROR_NOT_SUPPORTED;
	}

	*session_id = htab_hash(dev_identity);

	return LIBUSB_SUCCESS;
}

static void usbdk_release_config_descriptors(struct usbdk_device_priv *priv, uint8_t count)
{
	uint8_t i;

	for (i = 0; i < count; i++)
		usbdk_helper.ReleaseConfigurationDescriptor(priv->config_descriptors[i]);

	free(priv->config_descriptors);
	priv->config_descriptors = NULL;
}

static int usbdk_cache_config_descriptors(struct libusb_context *ctx,
	struct usbdk_device_priv *priv, PUSB_DK_DEVICE_INFO info)
{
	uint8_t i;
	USB_DK_CONFIG_DESCRIPTOR_REQUEST Request;
	Request.ID = info->ID;

	priv->config_descriptors = calloc(info->DeviceDescriptor.bNumConfigurations, sizeof(PUSB_CONFIGURATION_DESCRIPTOR));
	if (priv->config_descriptors == NULL) {
		usbi_err(ctx, "failed to allocate configuration descriptors holder");
		return LIBUSB_ERROR_NO_MEM;
	}

	for (i = 0; i < info->DeviceDescriptor.bNumConfigurations; i++) {
		ULONG Length;

		Request.Index = i;
		if (!usbdk_helper.GetConfigurationDescriptor(&Request, &priv->config_descriptors[i], &Length)) {
			usbi_err(ctx, "failed to retrieve configuration descriptors");
			usbdk_release_config_descriptors(priv, i);
			return LIBUSB_ERROR_OTHER;
		}
	}

	return LIBUSB_SUCCESS;
}

static inline int usbdk_device_priv_init(struct libusb_context *ctx, struct libusb_device *dev, PUSB_DK_DEVICE_INFO info)
{
	struct usbdk_device_priv *priv = usbi_get_device_priv(dev);

	priv->ID = info->ID;
	priv->active_configuration = 0;

	return usbdk_cache_config_descriptors(ctx, priv, info);
}

static void usbdk_device_init(struct libusb_device *dev, PUSB_DK_DEVICE_INFO info)
{
	dev->bus_number = (uint8_t)info->FilterID;
	dev->port_number = (uint8_t)info->Port;
	dev->parent_dev = NULL;

	// Addresses in libusb are 1-based
	dev->device_address = (uint8_t)(info->Port + 1);

	static_assert(sizeof(dev->device_descriptor) == sizeof(info->DeviceDescriptor),
		      "mismatch between libusb and OS device descriptor sizes");
	memcpy(&dev->device_descriptor, &info->DeviceDescriptor, LIBUSB_DT_DEVICE_SIZE);
	usbi_localize_device_descriptor(&dev->device_descriptor);

	switch (info->Speed) {
	case LowSpeed:
		dev->speed = LIBUSB_SPEED_LOW;
		break;
	case FullSpeed:
		dev->speed = LIBUSB_SPEED_FULL;
		break;
	case HighSpeed:
		dev->speed = LIBUSB_SPEED_HIGH;
		break;
	case SuperSpeed:
		dev->speed = LIBUSB_SPEED_SUPER;
		break;
	case NoSpeed:
	default:
		dev->speed = LIBUSB_SPEED_UNKNOWN;
		break;
	}
}

static int usbdk_get_device_list(struct libusb_context *ctx, struct discovered_devs **_discdevs)
{
	int r = LIBUSB_SUCCESS;
	ULONG i;
	struct discovered_devs *discdevs = NULL;
	ULONG dev_number;
	PUSB_DK_DEVICE_INFO devices;

	if (!usbdk_helper.GetDevicesList(&devices, &dev_number))
		return LIBUSB_ERROR_OTHER;

	for (i = 0; i < dev_number; i++) {
		unsigned long session_id;
		struct libusb_device *dev = NULL;

		if (usbdk_get_session_id_for_device(ctx, &devices[i].ID, &session_id))
			continue;

		dev = usbi_get_device_by_session_id(ctx, session_id);
		if (dev == NULL) {
			dev = usbi_alloc_device(ctx, session_id);
			if (dev == NULL) {
				usbi_err(ctx, "failed to allocate a new device structure");
				continue;
			}

			usbdk_device_init(dev, &devices[i]);
			if (usbdk_device_priv_init(ctx, dev, &devices[i]) != LIBUSB_SUCCESS) {
				libusb_unref_device(dev);
				continue;
			}
		}

		discdevs = discovered_devs_append(*_discdevs, dev);
		libusb_unref_device(dev);
		if (!discdevs) {
			usbi_err(ctx, "cannot append new device to list");
			r = LIBUSB_ERROR_NO_MEM;
			goto func_exit;
		}

		*_discdevs = discdevs;
	}

func_exit:
	usbdk_helper.ReleaseDevicesList(devices);
	return r;
}

static int usbdk_get_config_descriptor(struct libusb_device *dev, uint8_t config_index, void *buffer, size_t len)
{
	struct usbdk_device_priv *priv = usbi_get_device_priv(dev);
	PUSB_CONFIGURATION_DESCRIPTOR config_header;
	size_t size;

	config_header = (PUSB_CONFIGURATION_DESCRIPTOR)priv->config_descriptors[config_index];

	size = min(config_header->wTotalLength, len);
	memcpy(buffer, config_header, size);
	return (int)size;
}

static int usbdk_get_config_descriptor_by_value(struct libusb_device *dev, uint8_t bConfigurationValue,
	void **buffer)
{
	struct usbdk_device_priv *priv = usbi_get_device_priv(dev);
	PUSB_CONFIGURATION_DESCRIPTOR config_header;
	uint8_t index;

	for (index = 0; index < dev->device_descriptor.bNumConfigurations; index++) {
		config_header = priv->config_descriptors[index];
		if (config_header->bConfigurationValue == bConfigurationValue) {
			*buffer = priv->config_descriptors[index];
			return (int)config_header->wTotalLength;
		}
	}

	return LIBUSB_ERROR_NOT_FOUND;
}

static int usbdk_get_active_config_descriptor(struct libusb_device *dev, void *buffer, size_t len)
{
	struct usbdk_device_priv *priv = usbi_get_device_priv(dev);

	return usbdk_get_config_descriptor(dev, priv->active_configuration, buffer, len);
}

static int usbdk_open(struct libusb_device_handle *dev_handle)
{
	struct libusb_device *dev = dev_handle->dev;
	struct libusb_context *ctx = DEVICE_CTX(dev);
	struct windows_context_priv *priv = usbi_get_context_priv(ctx);
	struct usbdk_device_priv *device_priv = usbi_get_device_priv(dev);

	device_priv->redirector_handle = usbdk_helper.StartRedirect(&device_priv->ID);
	if (device_priv->redirector_handle == INVALID_HANDLE_VALUE) {
		usbi_err(ctx, "Redirector startup failed");
		device_priv->redirector_handle = NULL;
		return LIBUSB_ERROR_OTHER;
	}

	device_priv->system_handle = usbdk_helper.GetRedirectorSystemHandle(device_priv->redirector_handle);

	if (CreateIoCompletionPort(device_priv->system_handle, priv->completion_port, (ULONG_PTR)dev_handle, 0) == NULL) {
		usbi_err(ctx, "failed to associate handle to I/O completion port: %s", windows_error_str(0));
		usbdk_helper.StopRedirect(device_priv->redirector_handle);
		device_priv->system_handle = NULL;
		device_priv->redirector_handle = NULL;
		return LIBUSB_ERROR_OTHER;
	}

	return LIBUSB_SUCCESS;
}

static void usbdk_close(struct libusb_device_handle *dev_handle)
{
	struct usbdk_device_priv *priv = usbi_get_device_priv(dev_handle->dev);

	if (!usbdk_helper.StopRedirect(priv->redirector_handle))
		usbi_err(HANDLE_CTX(dev_handle), "Redirector shutdown failed");

	priv->system_handle = NULL;
	priv->redirector_handle = NULL;
}

static int usbdk_get_configuration(struct libusb_device_handle *dev_handle, uint8_t *config)
{
	struct usbdk_device_priv *priv = usbi_get_device_priv(dev_handle->dev);

	*config = priv->active_configuration;

	return LIBUSB_SUCCESS;
}

static int usbdk_set_configuration(struct libusb_device_handle *dev_handle, uint8_t config)
{
	UNUSED(dev_handle);
	UNUSED(config);
	return LIBUSB_SUCCESS;
}

static int usbdk_claim_interface(struct libusb_device_handle *dev_handle, uint8_t iface)
{
	UNUSED(dev_handle);
	UNUSED(iface);
	return LIBUSB_SUCCESS;
}

static int usbdk_set_interface_altsetting(struct libusb_device_handle *dev_handle, uint8_t iface, uint8_t altsetting)
{
	struct usbdk_device_priv *priv = usbi_get_device_priv(dev_handle->dev);

	if (!usbdk_helper.SetAltsetting(priv->redirector_handle, iface, altsetting)) {
		usbi_err(HANDLE_CTX(dev_handle), "SetAltsetting failed: %s", windows_error_str(0));
		return LIBUSB_ERROR_NO_DEVICE;
	}

	return LIBUSB_SUCCESS;
}

static int usbdk_release_interface(struct libusb_device_handle *dev_handle, uint8_t iface)
{
	UNUSED(dev_handle);
	UNUSED(iface);
	return LIBUSB_SUCCESS;
}

static int usbdk_clear_halt(struct libusb_device_handle *dev_handle, unsigned char endpoint)
{
	struct usbdk_device_priv *priv = usbi_get_device_priv(dev_handle->dev);

	if (!usbdk_helper.ResetPipe(priv->redirector_handle, endpoint)) {
		usbi_err(HANDLE_CTX(dev_handle), "ResetPipe failed: %s", windows_error_str(0));
		return LIBUSB_ERROR_NO_DEVICE;
	}

	return LIBUSB_SUCCESS;
}

static int usbdk_reset_device(struct libusb_device_handle *dev_handle)
{
	struct usbdk_device_priv *priv = usbi_get_device_priv(dev_handle->dev);

	if (!usbdk_helper.ResetDevice(priv->redirector_handle)) {
		usbi_err(HANDLE_CTX(dev_handle), "ResetDevice failed: %s", windows_error_str(0));
		return LIBUSB_ERROR_NO_DEVICE;
	}

	return LIBUSB_SUCCESS;
}

static void usbdk_destroy_device(struct libusb_device *dev)
{
	struct usbdk_device_priv *priv = usbi_get_device_priv(dev);

	if (priv->config_descriptors != NULL)
		usbdk_release_config_descriptors(priv, dev->device_descriptor.bNumConfigurations);
}

static void usbdk_clear_transfer_priv(struct usbi_transfer *itransfer)
{
	struct usbdk_transfer_priv *transfer_priv = get_usbdk_transfer_priv(itransfer);
	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);

	if (transfer->type == LIBUSB_TRANSFER_TYPE_ISOCHRONOUS) {
		safe_free(transfer_priv->IsochronousPacketsArray);
		safe_free(transfer_priv->IsochronousResultsArray);
	}
}

static int usbdk_do_control_transfer(struct usbi_transfer *itransfer)
{
	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
	struct usbdk_device_priv *priv = usbi_get_device_priv(transfer->dev_handle->dev);
	struct usbdk_transfer_priv *transfer_priv = get_usbdk_transfer_priv(itransfer);
	OVERLAPPED *overlapped = get_transfer_priv_overlapped(itransfer);
	TransferResult transResult;

	transfer_priv->request.Buffer = (PVOID64)transfer->buffer;
	transfer_priv->request.BufferLength = transfer->length;
	transfer_priv->request.TransferType = ControlTransferType;

	set_transfer_priv_handle(itransfer, priv->system_handle);

	if (transfer->buffer[0] & LIBUSB_ENDPOINT_IN)
		transResult = usbdk_helper.ReadPipe(priv->redirector_handle, &transfer_priv->request, overlapped);
	else
		transResult = usbdk_helper.WritePipe(priv->redirector_handle, &transfer_priv->request, overlapped);

	switch (transResult) {
	case TransferSuccess:
		windows_force_sync_completion(itransfer, (ULONG)transfer_priv->request.Result.GenResult.BytesTransferred);
		break;
	case TransferSuccessAsync:
		break;
	case TransferFailure:
		usbi_err(TRANSFER_CTX(transfer), "ControlTransfer failed: %s", windows_error_str(0));
		return LIBUSB_ERROR_IO;
	}

	return LIBUSB_SUCCESS;
}

static int usbdk_do_bulk_transfer(struct usbi_transfer *itransfer)
{
	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
	struct usbdk_device_priv *priv = usbi_get_device_priv(transfer->dev_handle->dev);
	struct usbdk_transfer_priv *transfer_priv = get_usbdk_transfer_priv(itransfer);
	OVERLAPPED *overlapped = get_transfer_priv_overlapped(itransfer);
	TransferResult transferRes;

	transfer_priv->request.Buffer = (PVOID64)transfer->buffer;
	transfer_priv->request.BufferLength = transfer->length;
	transfer_priv->request.EndpointAddress = transfer->endpoint;

	switch (transfer->type) {
	case LIBUSB_TRANSFER_TYPE_BULK:
		transfer_priv->request.TransferType = BulkTransferType;
		break;
	case LIBUSB_TRANSFER_TYPE_INTERRUPT:
		transfer_priv->request.TransferType = InterruptTransferType;
		break;
	}

	set_transfer_priv_handle(itransfer, priv->system_handle);

	if (IS_XFERIN(transfer))
		transferRes = usbdk_helper.ReadPipe(priv->redirector_handle, &transfer_priv->request, overlapped);
	else
		transferRes = usbdk_helper.WritePipe(priv->redirector_handle, &transfer_priv->request, overlapped);

	switch (transferRes) {
	case TransferSuccess:
		windows_force_sync_completion(itransfer, (ULONG)transfer_priv->request.Result.GenResult.BytesTransferred);
		break;
	case TransferSuccessAsync:
		break;
	case TransferFailure:
		usbi_err(TRANSFER_CTX(transfer), "ReadPipe/WritePipe failed: %s", windows_error_str(0));
		return LIBUSB_ERROR_IO;
	}

	return LIBUSB_SUCCESS;
}

static int usbdk_do_iso_transfer(struct usbi_transfer *itransfer)
{
	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
	struct usbdk_device_priv *priv = usbi_get_device_priv(transfer->dev_handle->dev);
	struct usbdk_transfer_priv *transfer_priv = get_usbdk_transfer_priv(itransfer);
	OVERLAPPED *overlapped = get_transfer_priv_overlapped(itransfer);
	TransferResult transferRes;
	int i;

	transfer_priv->request.Buffer = (PVOID64)transfer->buffer;
	transfer_priv->request.BufferLength = transfer->length;
	transfer_priv->request.EndpointAddress = transfer->endpoint;
	transfer_priv->request.TransferType = IsochronousTransferType;
	transfer_priv->request.IsochronousPacketsArraySize = transfer->num_iso_packets;
	transfer_priv->IsochronousPacketsArray = malloc(transfer->num_iso_packets * sizeof(ULONG64));
	transfer_priv->request.IsochronousPacketsArray = (PVOID64)transfer_priv->IsochronousPacketsArray;
	if (!transfer_priv->IsochronousPacketsArray) {
		usbi_err(TRANSFER_CTX(transfer), "Allocation of IsochronousPacketsArray failed");
		return LIBUSB_ERROR_NO_MEM;
	}

	transfer_priv->IsochronousResultsArray = malloc(transfer->num_iso_packets * sizeof(USB_DK_ISO_TRANSFER_RESULT));
	transfer_priv->request.Result.IsochronousResultsArray = (PVOID64)transfer_priv->IsochronousResultsArray;
	if (!transfer_priv->IsochronousResultsArray) {
		usbi_err(TRANSFER_CTX(transfer), "Allocation of isochronousResultsArray failed");
		return LIBUSB_ERROR_NO_MEM;
	}

	for (i = 0; i < transfer->num_iso_packets; i++)
		transfer_priv->IsochronousPacketsArray[i] = transfer->iso_packet_desc[i].length;

	set_transfer_priv_handle(itransfer, priv->system_handle);

	if (IS_XFERIN(transfer))
		transferRes = usbdk_helper.ReadPipe(priv->redirector_handle, &transfer_priv->request, overlapped);
	else
		transferRes = usbdk_helper.WritePipe(priv->redirector_handle, &transfer_priv->request, overlapped);

	switch (transferRes) {
	case TransferSuccess:
		windows_force_sync_completion(itransfer, (ULONG)transfer_priv->request.Result.GenResult.BytesTransferred);
		break;
	case TransferSuccessAsync:
		break;
	case TransferFailure:
		return LIBUSB_ERROR_IO;
	}

	return LIBUSB_SUCCESS;
}

static int usbdk_submit_transfer(struct usbi_transfer *itransfer)
{
	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);

	switch (transfer->type) {
	case LIBUSB_TRANSFER_TYPE_CONTROL:
		return usbdk_do_control_transfer(itransfer);
	case LIBUSB_TRANSFER_TYPE_BULK:
	case LIBUSB_TRANSFER_TYPE_INTERRUPT:
		if (IS_XFEROUT(transfer) && (transfer->flags & LIBUSB_TRANSFER_ADD_ZERO_PACKET))
			return LIBUSB_ERROR_NOT_SUPPORTED; //TODO: Check whether we can support this in UsbDk
		return usbdk_do_bulk_transfer(itransfer);
	case LIBUSB_TRANSFER_TYPE_ISOCHRONOUS:
		return usbdk_do_iso_transfer(itransfer);
	default:
		// Should not get here since windows_submit_transfer() validates
		// the transfer->type field
		usbi_err(TRANSFER_CTX(transfer), "unsupported endpoint type %d", transfer->type);
		return LIBUSB_ERROR_NOT_SUPPORTED;
	}
}

static enum libusb_transfer_status usbdk_copy_transfer_data(struct usbi_transfer *itransfer, DWORD length)
{
	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
	struct usbdk_transfer_priv *transfer_priv = get_usbdk_transfer_priv(itransfer);

	UNUSED(length);

	if (transfer->type == LIBUSB_TRANSFER_TYPE_ISOCHRONOUS) {
		ULONG64 i;

		for (i = 0; i < transfer_priv->request.IsochronousPacketsArraySize; i++) {
			struct libusb_iso_packet_descriptor *lib_desc = &transfer->iso_packet_desc[i];

			switch (transfer_priv->IsochronousResultsArray[i].TransferResult) {
			case STATUS_SUCCESS:
			case STATUS_CANCELLED:
			case STATUS_REQUEST_CANCELED:
				lib_desc->status = LIBUSB_TRANSFER_COMPLETED; // == ERROR_SUCCESS
				break;
			default:
				lib_desc->status = LIBUSB_TRANSFER_ERROR; // ERROR_UNKNOWN_EXCEPTION;
				break;
			}

			lib_desc->actual_length = (unsigned int)transfer_priv->IsochronousResultsArray[i].ActualLength;
		}
	}

	itransfer->transferred += (int)transfer_priv->request.Result.GenResult.BytesTransferred;
	return usbd_status_to_libusb_transfer_status((USBD_STATUS)transfer_priv->request.Result.GenResult.UsbdStatus);
}

const struct windows_backend usbdk_backend = {
	usbdk_init,
	usbdk_exit,
	usbdk_get_device_list,
	usbdk_open,
	usbdk_close,
	usbdk_get_active_config_descriptor,
	usbdk_get_config_descriptor,
	usbdk_get_config_descriptor_by_value,
	usbdk_get_configuration,
	usbdk_set_configuration,
	usbdk_claim_interface,
	usbdk_release_interface,
	usbdk_set_interface_altsetting,
	usbdk_clear_halt,
	usbdk_reset_device,
	usbdk_destroy_device,
	usbdk_submit_transfer,
	NULL,	/* cancel_transfer */
	usbdk_clear_transfer_priv,
	usbdk_copy_transfer_data,
};