PVOID HookFunction(const char *Dll, const char *FuncName, int Ordinal, void *Function)
{
	DWORD oldProtect;
	void *PrevValue=0;

	DWORD image_base = (DWORD)GetModuleHandle(NULL);
	IMAGE_DOS_HEADER *idh = (IMAGE_DOS_HEADER *)image_base;
	IMAGE_FILE_HEADER *ifh = (IMAGE_FILE_HEADER *)(image_base + idh->e_lfanew + sizeof(DWORD));
	IMAGE_OPTIONAL_HEADER *ioh = (IMAGE_OPTIONAL_HEADER *)((DWORD)(ifh) + sizeof(IMAGE_FILE_HEADER));
	IMAGE_IMPORT_DESCRIPTOR *iid = (IMAGE_IMPORT_DESCRIPTOR *)(image_base + ioh->DataDirectory[IMAGE_DIRECTORY_ENTRY_IMPORT].VirtualAddress);

	VirtualProtect((LPVOID)(image_base + ioh->DataDirectory[IMAGE_DIRECTORY_ENTRY_IAT].VirtualAddress), ioh->DataDirectory[IMAGE_DIRECTORY_ENTRY_IAT].Size, PAGE_READWRITE, &oldProtect);

	while(iid->Name)
	{
		if(_stricmp(Dll, (char *)(image_base + iid->Name)) == 0)
		{
			IMAGE_THUNK_DATA * pThunk = (IMAGE_THUNK_DATA *) ((DWORD)iid->OriginalFirstThunk + image_base);
			IMAGE_THUNK_DATA * pThunk2 = (IMAGE_THUNK_DATA *) ((DWORD)iid->FirstThunk + image_base);
			while(pThunk->u1.AddressOfData)
			{
				char * name = 0;
				int ordinal;

				if(pThunk->u1.Ordinal & 0x80000000)
				{
					ordinal = pThunk->u1.Ordinal & 0xffff;
				} else {    // Imported by name, with ordinal hint
					IMAGE_IMPORT_BY_NAME * pname = (IMAGE_IMPORT_BY_NAME *) ((DWORD)pThunk->u1.AddressOfData + image_base);
					ordinal = pname->Hint;
					name = (char *)pname->Name;
				}

				if(name != 0 && FuncName && strcmp(name, FuncName) == 0)
				{         
					PrevValue = (void*)pThunk2->u1.Function;
					pThunk2->u1.Function = (DWORD)Function;

				} else if(ordinal == Ordinal) {
					PrevValue = (void*)pThunk2->u1.Function;
					pThunk2->u1.Function = (DWORD)Function;
				}

				pThunk++;
				pThunk2++;
            	}
		}
		iid++;
    }
	return PrevValue;
}