全局钩子注入

// dllmain.cpp : 定义 DLL 应用程序的入口点。
#include "pch.h"
#include <Windows.h>

// C C++混用 声明
#ifdef __cplusplus
extern "C" {
#endif
    _declspec(dllexport) void OnHook();
    _declspec(dllexport) void OffHook();
#ifdef __cplusplus
    }
#endif

HHOOK g_hook = NULL;  //定义一个全局钩子遍历
HINSTANCE instance = NULL;

BOOL APIENTRY DllMain( HMODULE hModule,
                       DWORD  ul_reason_for_call,
                       LPVOID lpReserved
                     )
{
    switch (ul_reason_for_call)
    {
    case DLL_PROCESS_ATTACH:
        instance = hModule;
        MessageBoxA(0,"text", "title", 0);
        break;
    case DLL_THREAD_ATTACH:
    case DLL_THREAD_DETACH:
    case DLL_PROCESS_DETACH:
        break;
    }
    return TRUE;
}


LRESULT CALLBACK getMsgProc(int code, WPARAM wparam, LPARAM lparam) {
    return CallNextHookEx(g_hook, code, wparam, lparam);
}

void OnHook() {
    g_hook = SetWindowsHookEx(WH_GETMESSAGE, getMsgProc, instance, 0);
}
void OffHook() {
    UnhookWindowsHookEx(g_hook);
}

#include <Windows.h>

typedef void(*hookOn)();   //定义一个函数指针
typedef void(*hookOff)();
void main() {
	HMODULE hmod = LoadLibraryA("hookdll.dll");
	hookOn hook_on = (hookOn)GetProcAddress(hmod, "OnHook");
	hookOff hook_off = (hookOff)GetProcAddress(hmod, "OffHook");

	hook_on();
	system("pause");
	hook_off();
}