First Time Trying to use Hooks

[Mehungwaylo]

The code from my dll. Named newfile.dll. Compiled as:

gcc -c newfile.c
gcc -shared -o newfile.dll newfile.o

The file:

#include <windows.h>
#include <stdio.h>
#ifndef NEWFILE_H
#define NEWFILE_H

#ifdef __cplusplus
extern "C" {
#endif

__declspec(dllexport) void __stdcall MyFirstHook(){
printf("It works!");
}


#ifdef __cplusplus
}
#endif

#endif /* NEWFILE_H */

The main program:

#include <windows.h>

int main() {
HOOKPROC hkprcSysMsg;
HINSTANCE hinstDLL;
HHOOK hhookSysMsg;

hinstDLL = LoadLibrary(TEXT("newfile.dll"));
hkprcSysMsg = (HOOKPROC)GetProcAddress(hinstDLL, "MyFirstHook");

hhookSysMsg = SetWindowsHookEx(WH_KEYBOARD, hkprcSysMsg, hinstDLL,0);


return (EXIT_SUCCESS);
}

I'm trying to hook the keyboard and every time I press a key print out "it works!". I know I probably won't get much help, but anything is appreciated.

[m0mathur]

You are trying to make a Keylogger yeh?

[Mehungwaylo]

That is the end goal but really right now I'm just trying to learn.

[m0mathur]

I don't encourage malicious business, but read from this sources tho

For using SetWindowHook.
http://www.codeproject.com/Articles/187869/Your-Desktop-and-Microsoft-s-SetWindowsHookEx

GetAsyncKeyState.
http://msdn.microsoft.com/en-us/library/windows/desktop/ms646293(v=vs.85).aspx

Win32 API in general.
http://msdn.microsoft.com/en-us/library/windows/desktop/ff818516(v=vs.85).aspx

[13bSLyTq]

Hi,

In your given program there are multiple problems such as you forgetting, the message loop and more importantly forgot the essential part of this program - hook callback, however I have created an example code for you:

#include<Windows.h>
#include <stdio.h>

HHOOK hHock = NULL;

LRESULT CALLBACK MyLowLevelHookCallback ( int nCode , WPARAM wParam , LPARAM lParam) // Hook callback
{
    printf("Key press\n");
    return CallNextHookEx(hHock , nCode ,wParam , lParam); //Finished with our hook call-back, so lets move to next one. 
}

int main() //Entry point
{
    MSG msg;
    hHock = SetWindowsHookEx(WH_KEYBOARD_LL , MyLowLevelHookCallback , NULL,NULL); //Install global Keyboard hook

    while(!GetMessage(&msg, NULL, NULL, NULL)) { // Message Loop
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    UnhookWindowsHookEx(hHock); // uninstall global keyboard hook before exiting 
	return 0;
} 

Hope this helped,
OrionMaster