[C] CallAPIByName

[Nytro]

[C] CallAPIByName

LPVOID GetProcAddressEx(HMODULE hModule, LPCSTR lpProcName)
{
   DWORD dwModule = (DWORD)hModule;

   IMAGE_DOS_HEADER *Image_Dos_Header = (IMAGE_DOS_HEADER *)(dwModule);

   IMAGE_NT_HEADERS *Image_Nt_Headers = (IMAGE_NT_HEADERS *)(dwModule + Image_Dos_Header->e_lfanew);

   IMAGE_EXPORT_DIRECTORY *Image_Export_Directory = (IMAGE_EXPORT_DIRECTORY *)(dwModule + Image_Nt_Headers->OptionalHeader.DataDirectory->VirtualAddress);

   unsigned int nNumber;

   for (nNumber = 0; Image_Export_Directory->NumberOfNames; ++nNumber)
   {
      LPSTR lpAddressOfNames = ((*(LPSTR *)(Image_Export_Directory->AddressOfNames + dwModule + nNumber * sizeof(DWORD))) + dwModule);

      if (!lstrcmpA(lpProcName, lpAddressOfNames))
      {
         USHORT Ordinal = (*(USHORT *)(Image_Export_Directory->AddressOfNameOrdinals + dwModule + nNumber * sizeof(USHORT)));

         return (LPINT)((DWORD)*(LPVOID *)(Image_Export_Directory->AddressOfFunctions + dwModule + Ordinal * sizeof(LPVOID)) + dwModule);
      }
   }

   return NULL;
}

LPVOID WINAPI Invoke(LPCWSTR lpModuleName, LPCSTR lpProcName, int count, ...)
{
	HMODULE hModule;
	LPVOID lpProcAddress, lpResult = NULL;
	va_list list;
	void **args = (void **) HeapAlloc(GetProcessHeap(), 0, count);

	int x;

	if ((hModule = LoadLibrary(lpModuleName)) != 0)
	{
		if ((lpProcAddress = GetProcAddressEx(hModule,lpProcName)) != 0)
		{
			va_start(list,count);

			for (x = 0; x < count; x++)
				args[x] = va_arg(list, void *);

			for (x = count -1; x >= 0; x--)
			{
				int temp = x * 4;

				__asm
				{
					mov  eax, dword ptr args
					add  eax, temp
					push [eax]
				}
			}

			__asm
			{
				call lpProcAddress
				mov lpResult,eax
			}
		}
	}

	va_end(list);

	HeapFree(GetProcessHeap(), 0, args);
	FreeLibrary(hModule);

	return lpResult;
}

Example:

Invoke(L"USER32.DLL", "MessageBoxW", 4, 0, L"Hello World", L"Info!", 0);

Sursa: CallAPIByName [C]