为什么这个系统范围的 CBT 挂钩不能正常工作？

Question

我正在尝试创建一个系统范围的挂钩来监视进程并终止不需要的进程。我搜索并发现我需要使用 CBT 钩子，我的第一次尝试失败，这是第二次，前一个问题可以是 found here。

以下代码构建得很好，但似乎甚至没有调用挂钩，因为我尝试在DllMain() 中设置断点，但我从未到达那里。不过其他功能似乎可以访问！

这里是sn-ps的代码：

dllmain.cpp

// dllmain.cpp : Defines the entry point for the DLL application.
#pragma once
#include "stdafx.h"
#include <iostream>
#include <fstream>
#include <Windows.h>
using namespace std;

 HINSTANCE currentProcessHandle;
 HOOKPROC hkprcSysMsg;
 HHOOK hookID;

BOOL APIENTRY DllMain( HMODULE hModule, DWORD  ul_reason_for_call, LPVOID lpReserved)
{
    std::ofstream outfile("test.txt");


    switch (ul_reason_for_call)
    {
    case DLL_PROCESS_ATTACH:
        currentProcessHandle = hModule;
        break;
    case DLL_THREAD_ATTACH:
    case DLL_THREAD_DETACH:
    case DLL_PROCESS_DETACH:
        break;
    }
    return TRUE;
}

LRESULT CALLBACK HookProcedure(int nCode, WPARAM wparam, LPARAM lparam)
{
    std::ofstream outfile("test.txt");
    if (nCode >= 0)
    {
        switch (nCode)
        {
        case HCBT_CREATEWND:
            outfile << L"Created!~";
            cout << "Created!~" << endl;
            break;
        case HCBT_DESTROYWND:
            outfile << L"Destroied!~";
            cout << "Destroied!~" << endl;
            break;
        default:
            cout << "sth else" << endl;
            break;
        }
    }
    else
    {
        return CallNextHookEx(hookID, nCode, wparam, lparam);
    }
    outfile.close();
}

__declspec(dllexport) void InstallHook()
{
    hookID = SetWindowsHookEx(WH_CBT, HookProcedure, currentProcessHandle, 0);
}

__declspec(dllexport) void UnistallHook()
{
    UnhookWindowsHookEx(hookID);
}

这就是消费者应用程序

// Hook Executer.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include "..\Dll\dllmain.cpp"
#include <iostream>
using namespace std;

int _tmain(int argc, _TCHAR* argv[])
{
    int num = -1;
    cout << "1.Install Hook"<<endl
        << "2.Unistall Hook"<<endl
        << "0.Exit";
    do{
        cin >> num;
        if (num ==1)
        {
            InstallHook();

        }
        else
        {
            UnistallHook();
        }
        getchar();
        system("cls");
        cout << "1.Install Hook" << endl
            << "2.Unistall Hook" << endl
            << "0.Exit";
    } while (num != 0 && num < 3);


    return 0;
}

当我运行程序时，没有任何错误，甚至没有任何异常，就好像没有 DLL 或者我在该 DLL 中没有编写任何代码。它有什么问题？

Answer 1

在 CPP 文件中实现您的 DLL 代码，而不是在头文件中：

//dllmain.cpp
#include "stdafx.h" // include <Windows.h>
                    // and other std headers in stdafx.h, if not already done

HINSTANCE currentProcessHandle;
HHOOK hookID;

BOOL APIENTRY DllMain( HMODULE hModule, DWORD  ul_reason_for_call,
                       LPVOID lpReserved ) {

    if ( ul_reason_for_call == DLL_PROCESS_ATTACH )
        currentProcessHandle = hModule;
    return TRUE;
}

LRESULT CALLBACK HookProcedure( int nCode, WPARAM wparam, LPARAM lparam ) {

    if ( nCode < 0 ) return CallNextHookEx( NULL, nCode, wparam, lparam );

    std::ofstream outfile;
    outfile.open( "test.txt",          // replace with an absolute path
                  std::fstream::app ); // append mode
    if (nCode >= 0) {
        switch( nCode ) {
            case HCBT_CREATEWND:
                outfile << "Created!\n";
                break;
            case HCBT_DESTROYWND:
                outfile << "Destroyed!\n";
                break;
            default:
                break;
        }
    }
    outfile.close();
    return 0;
}

void InstallHook( void ) {
    hookID = SetWindowsHookEx( WH_CBT, HookProcedure, currentProcessHandle, 0 );
}

void UninstallHook( void ) { // NEW NAME
    UnhookWindowsHookEx( hookID );
}    

在头文件中声明 DLL API。

// dllapi.h
void InstallHook( void );
void UninstallHook( void ); // NEW NAME

使用DEF文件导出，添加到DLL项目中

; Def file
EXPORTS
    InstallHook
    UninstallHook

在 EXE 项目中，只包含 DLL 头文件

 #include "..\Dll\dllapi.h"

在EXE项目中，进入properties->Linker->Input->Additional dependencies，添加构建DLL时生成的lib文件。替代方案：在Solution的项目依赖项中使DLL成为EXE的依赖项，并在EXE属性中为Linker->general->Use Library dependency Inputs设置Yes