逆向分析_DLL基础(2)

DLL基础(2) 参数传递

//msgbox_arg.cpp
#include

extern "C" _declspec(dllexport) void __cdecl msgbox(HWND hwnd,HINSTANCE hinst, LPSTR lpszCmdLine,int nCmdShow);

void msgbox(HWND hwnd,HINSTANCE hinst, LPSTR lpszCmdLine,int nCmdShow)
{
	MessageBox(NULL,lpszCmdLine,"test",MB_OK);
}
//rundll32.exe msgbox_arg.dll,msgbox 123

DLL入口(DllMain entry point)

DllMain原型

BOOL WINAPI DllMain(
  _In_ HINSTANCE hinstDLL,
  _In_ DWORD     fdwReason,
  _In_ LPVOID    lpvReserved
);

运行时动态链接(Run-Time Dynamic Linking)

• 创建sum的dll release项目

//sum.cpp
extern "C" int __declspec(dllexport)add(int x, int y);

int add(int x, int y)
{
	return x + y;
}

• 创建win32 Console项目，加载sum.dll

//sum2.cpp
//把sum.dll复制到该项目下
#include 
#include 
#include 

typedef int(*lpAddFunc)(int,int);  //宏定义函数指针类型

int main(int argc, char *argv[])
{
	HINSTANCE hDll;			//DLL 句柄	
	lpAddFunc addFunc;		//函数指针
	hDll = LoadLibrary("sum.dll");
	if(hDll != NULL)
	{
		addFunc = (lpAddFunc)GetProcAddress(hDll,"add");
		if(addFunc != NULL)
		{
			int result = addFunc(2,3);
			printf("%d\n", result);
			system("pause");
		}
	}
	FreeLibrary(hDll);
	return 0;
}

dll静态调用

创建win32 Console项目

//static.cpp
//复制 sum.dll sum.lib 到本项目下
#include
#include

#pragma comment(lib,"sum.lib")
//.lib 文件中仅仅是关于其对应 DLL 文件中函数的重定位信息

extern "C" __declspec(dllimport) add(int x, int y);

int main(int argc, char* argv[])
{
	int result = add(2,3);
	printf("%d\n",result);
	system("pause");
	return 0;
}

参考

• Microsoft dllmain : https://docs.microsoft.com/en-us/windows/win32/dlls/dllmain
  参考