从高宏伟处借来的HOOK API代码

这是他的原链接：
    http://blog.donews.com/dukejoe/archive/2007/03/26/1144903.aspx

这是我以前在网上看到一段Hook API的代码。效果还不错，我把它收藏到我的Blog里，以便于以后查找。

#include <stdio.h>
#include <windows.h>
#include <Dbghelp.h>

#pragma comment(lib,"Dbghelp.lib")
#pragma comment(lib,"User32.lib")

typedef int (__stdcall *OLD_MessageBox)( HWND hWnd, LPCTSTR lpText, LPCTSTR lpCaption,UINT uType );

OLD_MessageBox g_procOldMessageBox = NULL;

int __stdcall HOOK_MessageBox( HWND hWnd, LPCTSTR lpText, LPCTSTR lpCaption,UINT uType)
{
    printf("%s\t%d\r\n",__FUNCTION__,__LINE__);
    if (NULL != g_procOldMessageBox)
        return g_procOldMessageBox(hWnd,lpText,"不好意思,hook到了!",uType);
    else
    return MessageBox(hWnd,lpText,lpCaption,uType); ;
}

int replace_IAT(const char *pDllName,const char *pApiName,bool bReplace)
{
    HANDLE hProcess = ::GetModuleHandle (NULL);
    DWORD dwSize = 0;
    PIMAGE_IMPORT_DESCRIPTOR pImageImport = (PIMAGE_IMPORT_DESCRIPTOR)ImageDirectoryEntryToData(hProcess,TRUE,
    IMAGE_DIRECTORY_ENTRY_IMPORT,&dwSize);
    if (NULL == pImageImport)
        return 1;
    PIMAGE_IMPORT_BY_NAME pImageImportByName = NULL;
    PIMAGE_THUNK_DATA pImageThunkOriginal = NULL;
    PIMAGE_THUNK_DATA pImageThunkReal = NULL;
    while (pImageImport->Name)
    {
        if (0 == strcmpi((char*)((PBYTE)hProcess+pImageImport->Name),pDllName))
        {
            break;
        }
        ++pImageImport;
    }
    if (! pImageImport->Name)
        return 2;
    pImageThunkOriginal = (PIMAGE_THUNK_DATA)((PBYTE)hProcess+pImageImport->OriginalFirstThunk );
    pImageThunkReal = (PIMAGE_THUNK_DATA)((PBYTE)hProcess+pImageImport->FirstThunk );
    while (pImageThunkOriginal->u1.Function)
    {
        if ((pImageThunkOriginal->u1.Ordinal & IMAGE_ORDINAL_FLAG) != IMAGE_ORDINAL_FLAG)
        {
            pImageImportByName = (PIMAGE_IMPORT_BY_NAME)((PBYTE)hProcess+pImageThunkOriginal->u1.AddressOfData );
            if (0 == strcmpi(pApiName,(char*)pImageImportByName->Name))
            {
                MEMORY_BASIC_INFORMATION mbi_thunk;
                VirtualQuery(pImageThunkReal, &mbi_thunk, sizeof(MEMORY_BASIC_INFORMATION));
                VirtualProtect(mbi_thunk.BaseAddress,mbi_thunk.RegionSize, PAGE_READWRITE, &mbi_thunk.Protect);
                if (true == bReplace)
                {
                    g_procOldMessageBox =(OLD_MessageBox) pImageThunkReal->u1.Function;
                    pImageThunkReal->u1.Function = (DWORD)HOOK_MessageBox;
                }
                else
                    pImageThunkReal->u1.Function = (DWORD)g_procOldMessageBox;
                DWORD dwOldProtect;
                VirtualProtect(mbi_thunk.BaseAddress, mbi_thunk.RegionSize, mbi_thunk.Protect, &dwOldProtect);
                break;
            }
        }
        ++pImageThunkOriginal;
        ++pImageThunkReal;
    }
    return 0;
}
int main()
{
    replace_IAT("User32.dll","MessageBoxA",true);
    MessageBox(NULL,"EnumIAT User32.dll MessageBoxA true;","",MB_OK);
    replace_IAT("User32.dll","MessageBoxA",false);
    MessageBox(NULL,"EnumIAT User32.dll MessageBoxA false;","",MB_OK);
    return getchar();
}