AfxCodeHook Example - Simple Api Hooking

Post date: Oct 17, 2010 10:39:22 PM

This code example details how to use afxcodehook (written by Aphex) to manipulate calls to windows apis.

program MsgBox;

uses

  Windows,

  afxCodeHook;

var

  MessageBoxANextHook: function(hWnd: HWND; lpText, lpCaption: PAnsiChar; uType: UINT): Integer; stdcall;

function MessageBoxAHookProc(hWnd: HWND; lpText, lpCaption: PAnsiChar; uType: UINT): Integer; stdcall;

begin

  Result := MessageBoxANextHook(0, '', 'bye', 0);

end;

begin

  //test the target API

  MessageBox(0, '', 'hi', 0);

  //hook the API

  HookCode('user32', 'MessageBoxA', @MessageBoxAHookProc, @MessageBoxANextHook);

  //the message should be changed

  MessageBox(0, '', 'hi', 0);

  //unhoook the API

  UnhookCode(@MessageBoxANextHook);

  //test the target API

  MessageBox(0, '', 'hi', 0);

end.