public int GetDescriptor(byte descriptorType, byte index, short langId, byte[] buffer, int offset, int length)
{
using (SafeFileHandle handle = Parent.OpenHandle()) {
int szRequest = Marshal.SizeOf(typeof(USB_DESCRIPTOR_REQUEST));
USB_DESCRIPTOR_REQUEST request = new USB_DESCRIPTOR_REQUEST();
request.ConnectionIndex = AdapterNumber;
request.SetupPacket.Value = (short)((descriptorType << 8) + index);
request.SetupPacket.Index = (short)langId;
request.SetupPacket.Length = (short)length;
int nBytes = length + szRequest;
Byte[] bigbuffer = new Byte[nBytes];
if (!Kernel32.DeviceIoControl(handle, UsbApi.IOCTL_USB_GET_DESCRIPTOR_FROM_NODE_CONNECTION, ref request, Marshal.SizeOf(typeof(USB_DESCRIPTOR_REQUEST)), bigbuffer, nBytes, out nBytes, IntPtr.Zero))
{
if (descriptorType == (Byte)UsbDescriptorType.Device && index == 0 && langId == 0)
{
Byte[] descbytes = DeviceDescriptor.GetBytes();
length = Math.Min(descbytes.Length, length);
Array.Copy(descbytes, 0, buffer, 0, length);
return(length);
}
int err = Marshal.GetLastWin32Error();
if (err != 31)
{
throw new Win32Exception(err);
}
return(0);
}
nBytes -= szRequest;
if (nBytes > length)
{
nBytes = length;
}
if (nBytes < 0)
{
return(0);
}
if (nBytes > 0)
{
Buffer.BlockCopy(bigbuffer, szRequest, buffer, offset, nBytes);
}
return(nBytes);
}
}