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System Hook question

Posted on 2000-04-28
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Last Modified: 2013-11-20
I'm using VC++ 6.0 and my application uses MFC. It is supposed to log all keyboard activities outside my application like hotkeys or etc...
How do I create a system hook? The MSDN library tells us to write it as a seperate library file or something, but I need more explanation on the actual process...

An example would really help a lot.
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Question by:Aphroditus
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Accepted Solution

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sun307 earned 100 total points
ID: 2762133
Hope this code will help you :-


#define NUMHOOKS 7
 
// Global variables
 
typedef struct _MYHOOKDATA
{
    int nType;
    HOOKPROC hkprc;
    HHOOK hhook;
} MYHOOKDATA;
 
MYHOOKDATA myhookdata[NUMHOOKS];
 
LRESULT WINAPI MainWndProc(HWND hwndMain, UINT uMsg, WPARAM wParam,
    LPARAM lParam)
{
    static BOOL afHooks[NUMHOOKS];
    int index;
    static HMENU hmenu;
 
    switch (uMsg)
    {
        case WM_CREATE:
 
            // Save the menu handle.
 
            hmenu = GetMenu(hwndMain);
 
            // Initialize structures with hook data. The menu-item
            // identifiers are defined as 0 through 6 in the
            // header file. They can be used to identify array
            // elements both here and during the WM_COMMAND
            // message.
 
            myhookdata[IDM_CALLWNDPROC].nType = WH_CALLWNDPROC;
            myhookdata[IDM_CALLWNDPROC].hkprc = CallWndProc;
            myhookdata[IDM_CBT].nType = WH_CBT;
            myhookdata[IDM_CBT].hkprc = CBTProc;
            myhookdata[IDM_DEBUG].nType = WH_DEBUG;
            myhookdata[IDM_DEBUG].hkprc = DebugProc;
            myhookdata[IDM_GETMESSAGE].nType = WH_GETMESSAGE;
            myhookdata[IDM_GETMESSAGE].hkprc = GetMsgProc;
            myhookdata[IDM_KEYBOARD].nType = WH_KEYBOARD;
            myhookdata[IDM_KEYBOARD].hkprc = KeyboardProc;
            myhookdata[IDM_MOUSE].nType = WH_MOUSE;
            myhookdata[IDM_MOUSE].hkprc = MouseProc;
            myhookdata[IDM_MSGFILTER].nType = WH_MSGFILTER;
            myhookdata[IDM_MSGFILTER].hkprc = MessageProc;
 
            // Initialize all flags in the array to FALSE.
 
            memset(afHooks, FALSE, sizeof(afHooks));
 
            return 0;
 
        case WM_COMMAND:
            switch (LOWORD(wParam))
            {
                 // The user selected a hook command from the menu.
 
                case IDM_CALLWNDPROC:
                case IDM_CBT:
                case IDM_DEBUG:
                case IDM_GETMESSAGE:
                case IDM_KEYBOARD:
                case IDM_MOUSE:
                case IDM_MSGFILTER:
 
                    // Use the menu-item identifier as an index
                    // into the array of structures with hook data.
 
                    index = LOWORD(wParam);
 
                    // If the selected type of hook procedure isn't
                    // installed yet, install it and check the
                    // associated menu item.
 
                    if (!afHooks[index])
                    {
                        myhookdata[index].hhook = SetWindowsHookEx(
                            myhookdata[index].nType,
                            myhookdata[index].hkprc,
                            (HINSTANCE) NULL, GetCurrentThreadId());
                        CheckMenuItem(hmenu, index,
                            MF_BYCOMMAND | MF_CHECKED);
                        afHooks[index] = TRUE;
                    }
 
                    // If the selected type of hook procedure is
                    // already installed, remove it and remove the
                    // check mark from the associated menu item.
 
                    else
                    {
                        UnhookWindowsHookEx(myhookdata[index].hhook);
                        CheckMenuItem(hmenu, index,
                            MF_BYCOMMAND | MF_UNCHECKED);
                        afHooks[index] = FALSE;
                    }
 
                default:
                    return (DefWindowProc(hwndMain, uMsg, wParam,
                        lParam));
            }
            break;
 
            //
            // Process other messages.
            //
 
        default:
            return DefWindowProc(hwndMain, uMsg, wParam, lParam);
    }
    return NULL;
}
 
/****************************************************************
  WH_CALLWNDPROC hook procedure
 ****************************************************************/
 
LRESULT WINAPI CallWndProc(int nCode, WPARAM wParam, LPARAM lParam)
{
    CHAR szCWPBuf[256];
    CHAR szMsg[16];
    HDC hdc;
    static int c = 0;
    int cch;
 
    if (nCode < 0)  // do not process message
        return CallNextHookEx(myhookdata[CALLWNDPROC].hhook, nCode,
                wParam, lParam);
 
    // Call an application-defined function that converts a message
    // constant to a string and copies it to a buffer.
 
    LookUpTheMessage((PMSG) lParam, szMsg);
 
    hdc = GetDC(hwndMain);
 
    switch (nCode)
    {
        case HC_ACTION:
            cch = wsprintf(szCWPBuf,
               "CALLWNDPROC - tsk: %ld, msg: %s, %d times   ",
                wParam, szMsg, c++);
            TextOut(hdc, 2, 15, szCWPBuf, cch);
            break;
 
        default:
            break;
    }
 
    ReleaseDC(hwndMain, hdc);
    return CallNextHookEx(myhookdata[CALLWNDPROC].hhook, nCode,
        wParam, lParam);
}
 
/****************************************************************
  WH_GETMESSAGE hook procedure
 ****************************************************************/
 
LRESULT CALLBACK GetMsgProc(int nCode, WPARAM wParam, LPARAM lParam)
{
    CHAR szMSGBuf[256];
    CHAR szRem[16];
    CHAR szMsg[16];
    HDC hdc;
    static int c = 0;
    int cch;
 
    if (nCode < 0) // do not process message
        return CallNextHookEx(myhookdata[GETMESSAGE].hhook, nCode,
            wParam, lParam);
 
    switch (nCode)
    {
        case HC_ACTION:
            switch (wParam)
            {
                case PM_REMOVE:
                    lstrcpy(szRem, "PM_REMOVE");
                    break;
 
                case PM_NOREMOVE:
                    lstrcpy(szRem, "PM_NOREMOVE");
                    break;
 
                default:
                    lstrcpy(szRem, "Unknown");
                    break;
            }
 
            // Call an application-defined function that converts a
            // message constant to a string and copies it to a
            // buffer.
 
            LookUpTheMessage((PMSG) lParam, szMsg);
 
            hdc = GetDC(hwndMain);
            cch = wsprintf(szMSGBuf,
                "GETMESSAGE - wParam: %s, msg: %s, %d times   ",
                szRem, szMsg, c++);
            TextOut(hdc, 2, 35, szMSGBuf, cch);
            break;
 
        default:
            break;
    }
 
    ReleaseDC(hwndMain, hdc);
    return CallNextHookEx(myhookdata[GETMESSAGE].hhook, nCode,
        wParam, lParam);
}
 
/****************************************************************
  WH_DEBUG hook procedure
 ****************************************************************/
 
LRESULT CALLBACK DebugProc(int nCode, WPARAM wParam, LPARAM lParam)
{
    CHAR szBuf[128];
    HDC hdc;
    static int c = 0;
    int cch;
 
    if (nCode < 0)  // do not process message
        return CallNextHookEx(myhookdata[DEBUG].hhook, nCode,
            wParam, lParam);
 
    hdc = GetDC(hwndMain);
 
    switch (nCode)
    {
        case HC_ACTION:
            cch = wsprintf(szBuf,
                "DEBUG - nCode: %d, tsk: %ld, %d times   ",
                nCode,wParam, c++);
            TextOut(hdc, 2, 55, szBuf, cch);
            break;
 
        default:
            break;
    }
 
    ReleaseDC(hwndMain, hdc);
    return CallNextHookEx(myhookdata[DEBUG].hhook, nCode, wParam,
        lParam);
}
 
/****************************************************************
  WH_CBT hook procedure
 ****************************************************************/
 
LRESULT CALLBACK CBTProc(int nCode, WPARAM wParam, LPARAM lParam)
{
    CHAR szBuf[128];
    CHAR szCode[128];
    HDC hdc;
    static int c = 0;
    int cch;
 
    if (nCode < 0)  // do not process message
        return CallNextHookEx(myhookdata[CBT].hhook, nCode, wParam,
            lParam);
 
    hdc = GetDC(hwndMain);
 
    switch (nCode)
    {
        case HCBT_ACTIVATE:
            lstrcpy(szCode, "HCBT_ACTIVATE");
            break;
 
        case HCBT_CLICKSKIPPED:
            lstrcpy(szCode, "HCBT_CLICKSKIPPED");
            break;
 
        case HCBT_CREATEWND:
            lstrcpy(szCode, "HCBT_CREATEWND");
            break;
 
        case HCBT_DESTROYWND:
            lstrcpy(szCode, "HCBT_DESTROYWND");
            break;
 
        case HCBT_KEYSKIPPED:
            lstrcpy(szCode, "HCBT_KEYSKIPPED");
            break;
 
        case HCBT_MINMAX:
            lstrcpy(szCode, "HCBT_MINMAX");
            break;
 
        case HCBT_MOVESIZE:
            lstrcpy(szCode, "HCBT_MOVESIZE");
            break;
 
        case HCBT_QS:
            lstrcpy(szCode, "HCBT_QS");
            break;
 
        case HCBT_SETFOCUS:
            lstrcpy(szCode, "HCBT_SETFOCUS");
            break;
 
        case HCBT_SYSCOMMAND:
            lstrcpy(szCode, "HCBT_SYSCOMMAND");
            break;
 
        default:
            lstrcpy(szCode, "Unknown");
            break;
    }
 
    cch = wsprintf(szBuf, "CBT - nCode: %s, tsk: %ld, %d times   ",
        szCode, wParam, c++);
    TextOut(hdc, 2, 75, szBuf, cch);
    ReleaseDC(hwndMain, hdc);
    return CallNextHookEx(myhookdata[CBT].hhook, nCode, wParam,
        lParam);
}
 
/****************************************************************
  WH_MOUSE hook procedure
 ****************************************************************/
 
LRESULT CALLBACK MouseProc(int nCode, WPARAM wParam, LPARAM lParam)
{
    CHAR szBuf[128];
    CHAR szMsg[16];
    HDC hdc;
    static int c = 0;
    int cch;
 
    if (nCode < 0)  // do not process the message
        return CallNextHookEx(myhookdata[MOUSE].hhook, nCode,
            wParam, lParam);
 
    // Call an application-defined function that converts a message
    // constant to a string and copies it to a buffer.
 
    LookUpTheMessage((PMSG) lParam, szMsg);
 
    hdc = GetDC(hwndMain);
    cch = wsprintf(szBuf,
        "MOUSE - nCode: %d, msg: %s, x: %d, y: %d, %d times   ",
        nCode, szMsg, LOWORD(lParam), HIWORD(lParam), c++);
    TextOut(hdc, 2, 95, szBuf, cch);
    ReleaseDC(hwndMain, hdc);
    return CallNextHookEx(myhookdata[MOUSE].hhook, nCode, wParam,
        lParam);
}
 
/****************************************************************
  WH_KEYBOARD hook procedure
 ****************************************************************/
 
LRESULT CALLBACK KeyboardProc(int nCode, WPARAM wParam, LPARAM lParam)
{
    CHAR szBuf[128];
    HDC hdc;
    static int c = 0;
    int cch;
 
    if (nCode < 0)  // do not process message
        return CallNextHookEx(myhookdata[KEYBOARD].hhook, nCode,
            wParam, lParam);
 
    hdc = GetDC(hwndMain);
    cch = wsprintf(szBuf, "KEYBOARD - nCode: %d, vk: %d, %d times ",
        nCode, wParam, c++);
    TextOut(hdc, 2, 115, szBuf, cch);
    ReleaseDC(hwndMain, hdc);
    return CallNextHookEx(myhookdata[KEYBOARD].hhook, nCode, wParam,
        lParam);
}
 
/****************************************************************
  WH_MSGFILTER hook procedure
 ****************************************************************/
 
LRESULT CALLBACK MessageProc(int nCode, WPARAM wParam, LPARAM lParam)
{
    CHAR szBuf[128];
    CHAR szMsg[16];
    CHAR szCode[32];
    HDC hdc;
    static int c = 0;
    int cch;
 
    if (nCode < 0)  // do not process message
        return CallNextHookEx(myhookdata[MSGFILTER].hhook, nCode,
            wParam, lParam);
 
    switch (nCode)
    {
        case MSGF_DIALOGBOX:
            lstrcpy(szCode, "MSGF_DIALOGBOX");
            break;
 
        case MSGF_MENU:
            lstrcpy(szCode, "MSGF_MENU");
            break;
 
        case MSGF_SCROLLBAR:
            lstrcpy(szCode, "MSGF_SCROLLBAR");
            break;
 
        default:
            wsprintf(szCode, "Unknown: %d", nCode);
            break;
    }
 
    // Call an application-defined function that converts a message
    // constant to a string and copies it to a buffer.
 
    LookUpTheMessage((PMSG) lParam, szMsg);
 
    hdc = GetDC(hwndMain);
    cch = wsprintf(szBuf,
        "MSGFILTER  nCode: %s, msg: %s, %d times    ",
        szCode, szMsg, c++);
    TextOut(hdc, 2, 135, szBuf, cch);
    ReleaseDC(hwndMain, hdc);
    return CallNextHookEx(myhookdata[MSGFILTER].hhook, nCode,
        wParam, lParam);
}



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Author Comment

by:Aphroditus
ID: 2762291
Thanks!
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