win9xconhook.c

Apache 2.0.63 is the current stable version of the 2.0 series, and is recommended over any previous

        return 0;
    }

    while (GetMessage(&msg, NULL, 0, 0)) 
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    /* Tag again as deleted, just in case we missed WM_DESTROY */
    monitor_hwnd = NULL;
    return 0;
}


/* This is the WndProc procedure for our invisible window.
 * When our subclasssed tty window receives the WM_CLOSE, WM_ENDSESSION,
 * or WM_QUERYENDSESSION messages, the message is dispatched to our hidden
 * window (this message process), and we call the installed HandlerRoutine 
 * that was registered by the app.
 */
static LRESULT CALLBACK ttyConsoleCtrlWndProc(HWND hwnd, UINT msg, 
                                              WPARAM wParam, LPARAM lParam)
{
    if (msg == WM_CREATE)
    {
        tty_info *tty = (tty_info*)(((LPCREATESTRUCT)lParam)->lpCreateParams);
        SetWindowLong(hwnd, gwltty_phandler, (LONG)tty->phandler);
        SetWindowLong(hwnd, gwltty_ttywnd, (LONG)tty->parent);
#ifdef DBG
        DbgPrintf("A proc %8.8x created %8.8x %s for tty wnd %8.8x\r\n", 
                  GetCurrentProcessId(), hwnd, 
                  tty->name, tty->parent);
#endif
        if (tty->parent) {
            SetProp(tty->parent, hookwndprop, hwnd);
            PostMessage(tty->parent, hookwndmsg, 
                        tty->type, (LPARAM)tty->parent); 
        }
        return 0;
    }
    else if (msg == WM_DESTROY)
    {
        HWND parent = (HWND)GetWindowLong(hwnd, gwltty_ttywnd);
#ifdef DBG
        DbgPrintf("A proc %8.8x destroyed %8.8x ttyConHookChild\r\n",
                  GetCurrentProcessId(), hwnd);
#endif
        if (parent) {
            RemoveProp(parent, hookwndprop);
            SendMessage(parent, hookwndmsg, 0, (LPARAM)parent); 
        }
        monitor_hwnd = NULL;
    }
    else if (msg == WM_CLOSE)
    {
        PHANDLER_ROUTINE phandler = 
            (PHANDLER_ROUTINE)GetWindowLong(hwnd, gwltty_phandler);
        LRESULT rv = phandler(CTRL_CLOSE_EVENT);
#ifdef DBG
        DbgPrintf("A proc %8.8x invoked CTRL_CLOSE_EVENT "
                  "returning %d\r\n",
                  GetCurrentProcessId(), rv);
#endif
        if (rv)
            return !rv;
    }
    else if ((msg == WM_QUERYENDSESSION) || (msg == WM_ENDSESSION))
    {
        if (lParam & ENDSESSION_LOGOFF) 
        {
            PHANDLER_ROUTINE phandler = 
                (PHANDLER_ROUTINE)GetWindowLong(hwnd, gwltty_phandler);
            LRESULT rv = phandler(CTRL_LOGOFF_EVENT);
#ifdef DBG
            DbgPrintf("A proc %8.8x invoked CTRL_LOGOFF_EVENT "
                      "returning %d\r\n",
                      GetCurrentProcessId(), rv);
#endif
            if (rv)
                return ((msg == WM_QUERYENDSESSION) ? rv : !rv);
        }
        else
        {
            PHANDLER_ROUTINE phandler = 
                (PHANDLER_ROUTINE)GetWindowLong(hwnd, gwltty_phandler);
            LRESULT rv = phandler(CTRL_SHUTDOWN_EVENT);
#ifdef DBG
            DbgPrintf("A proc %8.8x invoked CTRL_SHUTDOWN_EVENT "
                      "returning %d\r\n", GetCurrentProcessId(), rv);
#endif
            if (rv)
                return ((msg == WM_QUERYENDSESSION) ? rv : !rv);
        }
    }
    return (DefWindowProc(hwnd, msg, wParam, lParam));
}


/*  The following internal helpers are invoked by the hooked tty and our app
 */

 
/*  Register or deregister the current process as a Windows9x style service.
 *  Experience shows this call is ignored across processes, so the second
 *  arg to RegisterServiceProcess (process group id) is effectively useless.
 */
static LRESULT WINAPI RegisterWindows9xService(BOOL set_service)
{
    static HINSTANCE hkernel;
    static DWORD (WINAPI *register_service_process)(DWORD, DWORD) = NULL;
    BOOL rv;

    if (set_service == is_service)
        return 1;

#ifdef DBG
    DbgPrintf("R %s proc %8.8x as a service\r\n",
              set_service ? "installing" : "removing",
              GetCurrentProcessId());
#endif

    if (!register_service_process)
    {
        /* Obtain a handle to the kernel library */
        hkernel = LoadLibrary("KERNEL32.DLL");
        if (!hkernel)
            return 0;
    
        /* Find the RegisterServiceProcess function */
        register_service_process = (DWORD (WINAPI *)(DWORD, DWORD))
                         GetProcAddress(hkernel, "RegisterServiceProcess");
        if (register_service_process == NULL) {
            FreeLibrary(hkernel);
            return 0;
        }
    }
    
    /* Register this process as a service */
    rv = register_service_process(0, set_service != FALSE);
    if (rv)
        is_service = set_service;
    
    if (!is_service)
    {
        /* Unload the kernel library */
        FreeLibrary(hkernel);
        register_service_process = NULL;
    }
    return rv;
}


/* 
 * This function only works when this process is the active process 
 * (e.g. once it is running a child process, it can no longer determine 
 * which console window is its own.)
 */
static BOOL CALLBACK EnumttyWindow(HWND wnd, LPARAM retwnd)
{
    char tmp[8];
    if (GetClassName(wnd, tmp, sizeof(tmp)) && !strcmp(tmp, "tty")) 
    {
        DWORD wndproc, thisproc = GetCurrentProcessId();
        GetWindowThreadProcessId(wnd, &wndproc);
        if (wndproc == thisproc) {
            *((HWND*)retwnd) = wnd;
            return FALSE;
        }
    }
    return TRUE;
}


/* The remaining code all executes --in the tty's own process context--
 *
 * That means special attention must be paid to what it's doing...
 */

/* Subclass message process for the tty window
 *
 * This code -handles- WM_CLOSE, WM_ENDSESSION and WM_QUERYENDSESSION
 * by dispatching them to the window identified by the hookwndprop
 * property atom set against our window.  Messages are then dispatched
 * to origwndprop property atom we set against the window when we
 * injected this subclass.  This trick did not work with simply a hook.
 */
static LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, 
                                WPARAM wParam, LPARAM lParam)
{
    WNDPROC origproc = (WNDPROC) GetProp(hwnd, origwndprop);
    if (!origproc)
        return 0;

    if (msg == WM_NCDESTROY 
        || (msg == hookwndmsg && !LOWORD(wParam) && (HWND)lParam == hwnd))
    {
        if (is_subclassed) {
#ifdef DBG
            DbgPrintf("W proc %08x hwnd:%08x Subclass removed\r\n", 
                      GetCurrentProcessId(), hwnd);
#endif
            if (is_service)
                RegisterWindows9xService(FALSE);
            SetWindowLong(hwnd, GWL_WNDPROC, (LONG)origproc);
            RemoveProp(hwnd, origwndprop);
            RemoveProp(hwnd, hookwndprop);
            is_subclassed = FALSE;
            //if (hmodLock)
            //    FreeLibrary(hmodLock);
            //hmodLock = NULL;
        }
    }
    else if (msg == WM_CLOSE || msg == WM_ENDSESSION 
                             || msg == WM_QUERYENDSESSION)
    {
        HWND child = (HWND)GetProp(hwnd, hookwndprop);
        if (child) {
#ifdef DBG
            DbgPrintf("W proc %08x hwnd:%08x forwarded msg:%d\r\n", 
                      GetCurrentProcessId(), hwnd, msg);
#endif
            return SendMessage(child, msg, wParam, lParam);
        }
    }
    return CallWindowProc(origproc, hwnd, msg, wParam, lParam);
}


/* HookProc, once installed, is responsible for subclassing the system
 * tty windows.  It generally does nothing special itself, since
 * research indicates that it cannot deal well with the messages we are
 * interested in, that is, WM_CLOSE, WM_QUERYSHUTDOWN and WM_SHUTDOWN
 * of the tty process.
 *
 * Respond and subclass only when a WM_NULL is received by the window.
 */
int HookProc(int hc, HWND *hwnd, UINT *msg, WPARAM *wParam, LPARAM *lParam)
{
    if (is_tty == -1 && *hwnd) 
    {
        char ttybuf[8];
        HWND htty;
        hwtty = *hwnd;
        while (htty = GetParent(hwtty))
            hwtty = htty;
        is_tty = (GetClassName(hwtty, ttybuf, sizeof(ttybuf)) 
                  && !strcmp(ttybuf, "tty"));
#ifdef DBG
        if (is_tty)
            DbgPrintf("H proc %08x tracking hwnd %08x\r\n", 
                      GetCurrentProcessId(), hwtty);
#endif
    }

    if (*msg == hookwndmsg && *wParam && *lParam == (LPARAM)hwtty && is_tty)
    {
        WNDPROC origproc = (WNDPROC)GetWindowLong(hwtty, GWL_WNDPROC);
        //char myname[MAX_PATH];
        //if (GetModuleFileName(hmodThis, myname, sizeof(myname)))
        //    hmodLock = LoadLibrary(myname);        
        SetProp(hwtty, origwndprop, origproc);
        SetWindowLong(hwtty, GWL_WNDPROC, (LONG)WndProc);
        is_subclassed = TRUE;
#ifdef DBG
        DbgPrintf("H proc %08x hwnd:%08x Subclassed\r\n", 
                  GetCurrentProcessId(), hwtty);
#endif
        if (LOWORD(*wParam) == 2)
            RegisterWindows9xService(TRUE);
    }

    return -1;
}


/*
 * PostMessage Hook:
 */
LRESULT __declspec(dllexport) CALLBACK GetMsgProc(INT hc, WPARAM wParam, 
                                                  LPARAM lParam)
{
    PMSG pmsg;

    pmsg = (PMSG)lParam;

    if (pmsg) {
        int rv = HookProc(hc, &pmsg->hwnd, &pmsg->message, 
                          &pmsg->wParam, &pmsg->lParam);
        if (rv != -1)
            return rv;
    }
    /* 
     * CallNextHookEx apparently ignores the hhook argument, so pass NULL
     */
    return CallNextHookEx(NULL, hc, wParam, lParam);
}


/*
 * SendMessage Hook:
 */
LRESULT __declspec(dllexport) CALLBACK CallWndProc(INT hc, WPARAM wParam, 
                                                   LPARAM lParam)
{
    PCWPSTRUCT pcwps = (PCWPSTRUCT)lParam;
    
    if (pcwps) {
        int rv = HookProc(hc, &pcwps->hwnd, &pcwps->message, 
                          &pcwps->wParam, &pcwps->lParam);
        if (rv != -1)
            return rv;
    }
    /* 
     * CallNextHookEx apparently ignores the hhook argument, so pass NULL
     */
    return CallNextHookEx(NULL, hc, wParam, lParam);
}


#ifdef DBG
VOID DbgPrintf(
    LPTSTR fmt,
    ...
    )
{
    static HANDLE mutex;
    va_list marker;
    TCHAR szBuf[256];
    DWORD t;
    HANDLE gDbgOut;

    va_start(marker, fmt);
    wvsprintf(szBuf, fmt, marker);
    va_end(marker);

    if (!mutex)
        mutex = CreateMutex(NULL, FALSE, "Win9xConHookDbgOut");
    WaitForSingleObject(mutex, INFINITE);
    gDbgOut = CreateFile("COM1", GENERIC_READ | GENERIC_WRITE, 0,
                         NULL, OPEN_EXISTING, FILE_FLAG_WRITE_THROUGH, NULL);
    WriteFile(gDbgOut, szBuf, strlen(szBuf), &t, NULL);
    CloseHandle(gDbgOut);
    ReleaseMutex(mutex);
}
#endif

#endif /* WIN32 */