Keyboard filter to simulate keys

Discussion in 'Windows Vista Drivers' started by Mel, Sep 21, 2004.

  1. Mel

    Mel Guest

    Hello,

    I'm new to driver development, in fact I have never written
    a real mode sys file nor a driver. Now I have to accomplish the following
    task:
    A program generates virtual key events to control a directx game.
    Because directx directly reads out the keyboard I can't simply use the
    WinAPI keybd_event or a simple SendKeys function. So the best way
    seems to be to send the keystrokes from my application (can be delphi, c++
    or vb)
    to the keyboard filter driver that creates the keystroke.

    Therefore I register a new keyboardchain filter KbdFilterInit

    Then I'd like to feed keys into the keyboard chain to simulate button press
    events. Therefore I create KeyData packets.

    To process the keyboard chain I implement proper dispatch
    function for reading
    NTSTATUS
    KbdDispatchRead(
    IN PDEVICE_OBJECT DeviceObject,
    IN PIRP Irp
    )

    So my questions are:
    Is there already something similar out there that I can use?
    Is it possible to create such a driver file without getting 1000s of
    blue screens?
    What's the easiest way to do this.
    How can I send some bytes from my app to the driver? (My app tells the
    driver to generate an 'F1' keystroke...)
    Is my theory correct?

    I hope to get some help from you.
    Thanks for any hints
    Mel

    NTSTATUS
    KbdFilterInit(
    IN PDRIVER_OBJECT DriverObject
    )
    /*++

    Routine Description:

    Create a device object and attaches it to the
    first keyboard device chain

    Arguments:

    DeviceObject - pointer to a device object.

    Return Value:

    NT Status code

    --*/


    {
    UNICODE_STRING ntUnicodeString;
    NTSTATUS ntStatus;
    PDEVICE_OBJECT DeviceObject = NULL;

    //
    // Only hook onto the first keyboard's chain.
    //
    RtlInitUnicodeString( &ntUnicodeString, L"\\Device\\KeyboardClass0" );
    //
    // Create device object for the keyboard.
    //
    ntStatus = IoCreateDevice( DriverObject,
    0,
    NULL,
    FILE_DEVICE_KEYBOARD,
    0,
    FALSE,
    &DeviceObject );

    if( !NT_SUCCESS(ntStatus) ) {
    JKBD_DbgPrint(("JKBD: Keyboard hook failed to create device!\n"));
    return ntStatus;
    }
    //
    // Keyboard uses buffered I/O so we must as well.
    //
    DeviceObject->Flags |= DO_BUFFERED_IO;
    //
    // Attach to the keyboard chain.
    //
    ntStatus = IoAttachDevice( DeviceObject, &ntUnicodeString,
    &pGlobalDevExt->KbdDevice );
    if( !NT_SUCCESS(ntStatus) ) {
    JKBD_DbgPrint(("JKBD: Connect with keyboard failed!\n"));
    IoDeleteDevice( DeviceObject );
    return ntStatus;
    }
    pGlobalDevExt->KbdFilterDevice = DeviceObject;

    return STATUS_SUCCESS;
    }



    //
    // Create a keyboard packet
    //
    KeyData = pGlobalDevExt->RawKbdIrp->AssociatedIrp.SystemBuffer;

    RtlZeroMemory(KeyData, 2*sizeof(KEYBOARD_INPUT_DATA));
    KeyData[numKeys].Flags = 0; //down
    KeyData[numKeys+1].Flags = 1; //up
    KeyData[numKeys].MakeCode = 0x1e; // character a
    KeyData[numKeys+1].MakeCode = 0x1e; // character a
    numKeys += 2;
    KeyData += numKeys*sizeof(KEYBOARD_INPUT_DATA);
    pGlobalDevExt->RawKbdIrp->IoStatus.Status = STATUS_SUCCESS;
    pGlobalDevExt->RawKbdIrp->IoStatus.Information =
    numKeys*sizeof(KEYBOARD_INPUT_DATA);
    pGlobalDevExt->RawKbdIrpPending = FALSE;
    IoCompleteRequest(pGlobalDevExt->RawKbdIrp, IO_KEYBOARD_INCREMENT);
     
    Mel, Sep 21, 2004
    #1
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  2. Look at DDK\DDKXP\src\input\kbfiltr example and how
    app talk to driver with IOCTL (
    http://support.microsoft.com/default.aspx?scid=kb;EN-US;Q262305 )
    Arkady

     
    Arkady Frenkel, Sep 21, 2004
    #2
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  3. which OS do you need this to work on? if it is win2k and forward, you can
    just use SendInput() from user mode.

    d

    --
    Please do not send e-mail directly to this alias. this alias is for
    newsgroup purposes only.
    This posting is provided "AS IS" with no warranties, and confers no rights.


     
    Doron Holan [MS], Sep 21, 2004
    #3
  4. Mel

    Mel Guest

    Thanks for your help.
    SendInput sounds really easy, too easy.
    Some forums mention that directx really reads
    the keyboard events directly from the keyboard
    and things like keybd_event or SendInput wont work.

    There is a way to hook the Directx Api function SendDeviceData and
    inject keystrokes there. But therefgore you have to replace the directx dll
    with your own.

    I work with win2k and winxp.

    Thanks for your tips.
    -Mel

    which OS do you need this to work on? if it is win2k and forward, you can
    just use SendInput() from user mode.

    d

    --
    Please do not send e-mail directly to this alias. this alias is for
    newsgroup purposes only.
    This posting is provided "AS IS" with no warranties, and confers no rights.


     
    Mel, Sep 21, 2004
    #4
  5. Mel

    Ray Trent Guest

    Well, don't believe everything you read here (including this :).

    SendInput works fine with DirectInput on 2k and XP.

    Of course, it may be possible to create a situation where it doesn't
    work, like some app opening a *specific* keyboard instead of the
    meta-keyboard GUID_SysKeyboard (I haven't verified this scenario). But
    even with a filter, you're going to have that problem, because you can't
    send your keys to *all* keyboards with a filter, just to one particular
    one (otherwise you'd end up with duplicate key presses, which you
    probably don't want).
     
    Ray Trent, Sep 21, 2004
    #5
  6. ray's right. SendInput() will work just fine for you. no need for a
    driver.

    d
     
    Doron Holan [MS], Sep 22, 2004
    #6
  7. Mel

    Mel Guest

    Thanks for your opinions. I will implement the SendInput option,
    this really saves me a lot of work.
    In one or two days I will know if it works with DirectX or not.

    Thanks
    Mel


    which OS do you need this to work on? if it is win2k and forward, you can
    just use SendInput() from user mode.

    d

    --
    Please do not send e-mail directly to this alias. this alias is for
    newsgroup purposes only.
    This posting is provided "AS IS" with no warranties, and confers no rights.


     
    Mel, Sep 22, 2004
    #7
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