本地键盘挂钩终止目标进程

Question

我正在尝试使用来自托管 C# 代码的 C++ DLL 将本地键盘挂钩安装到进程中，如下所示：

public class KeyboardHook
{
    [UnmanagedFunctionPointer(CallingConvention.StdCall)]
    public delegate IntPtr HookCallback(int nCode, IntPtr wParam, IntPtr lParam);

    [DllImport("DLL.dll", CallingConvention = CallingConvention.Cdecl)]
    protected static extern IntPtr Install(int idHook, IntPtr windowHandle, HookCallback callback);

    private IntPtr instance;
    private HookCallback handler;

    public KeyboardHook()
    {
        instance = IntPtr.Zero;
        handler = Callback;
    }

    public void Install(Process process)
    {
        instance = Install(WH_KEYBOARD, process.MainWindowHandle, handler);
    }

    public void Uninstall()
    {
        UnhookWindowsHookEx(instance);
    }

    private IntPtr Callback(int nCode, IntPtr wParam, IntPtr lParam)
    {
        // TODO Use hook data here

        return CallNextHookEx(instance, nCode, wParam, lParam);
    }
}

C++ DLL 代码应该足以将挂钩数据分派到 C# 的Callback function，如下所示：

// dll.h
#pragma data_seg(".foo")
HOOKPROC _hookCallback = NULL;
#pragma comment(linker, "/SECTION:.foo,RWS")
#pragma data_seg()

static HINSTANCE _moduleHandle = NULL;

extern "C" __declspec(dllexport)
HHOOK Install(int idHook, HWND window, HOOKPROC hookCallback);

extern "C" __declspec(dllexport)
LRESULT CALLBACK HookProc(int code, WPARAM wparam, LPARAM lparam);

// dll.cpp
HHOOK Install(int idHook, HWND window, HOOKPROC hookCallback)
{
    auto processId = 0ul;
    auto threadId = GetWindowThreadProcessId(window, &processId);

    _hookCallback = hookCallback;
    _hookCallback(-1, NULL, NULL); // Test callback (works)

    return SetWindowsHookExA(idHook, HookProc, _moduleHandle, threadId);
}

LRESULT CALLBACK HookProc(int code, WPARAM wParam, LPARAM lParam)
{
    // The following line terminates the target process
    return _hookCallback(code, wParam, lParam);
}

BOOL APIENTRY DllMain(HMODULE hModule, DWORD ul_reason_for_call, LPVOID lpReserved)
{
    switch (ul_reason_for_call)
    {
        case DLL_PROCESS_ATTACH:
            _moduleHandle = hModule;
            break;
        case DLL_PROCESS_DETACH:
        case DLL_THREAD_ATTACH:
        case DLL_THREAD_DETACH:
            break;
    }

    return TRUE;
}

The local hook is successfuly installed as the DLL KeyboardProc function is triggered, however, calling the C# delegate from the C++ DLL terminates the application. 为什么？

笔记：

1. DLL 和应用程序都是 32 位
2. _hookCallback_在触发 HookProc 时不是HookProc （虽然我不确定它是否指向有效的 memory 地址）
3. KeyboardProc::handler不应被垃圾回收，因为 KeyboardProc 实例的存在时间与 C# 应用程序一样长
4. 在 DLL 的Install function 中使用_hookCallback function 指针可以完美地工作，但在HookProc ZC1C425268E68385D1AB5074C17A9 中使用时会终止进程。
5. 没有例外或任何情况，该过程只是突然终止

还尝试过什么：

使HookCallback成为UnmanagedFunctionPointer ，以及使用Marshal.GetFunctionPointerForDelegate并使用GCHandle.Alloc()和GC.KeepAlive()告诉垃圾收集器不要收集handler属性：

public class KeyboardHook
{
    [UnmanagedFunctionPointer(CallingConvention.StdCall)]
    public delegate IntPtr HookCallback(int nCode, IntPtr wParam, IntPtr lParam);

    [DllImport("DLL32.dll", CallingConvention = CallingConvention.Cdecl)]
    protected static extern IntPtr Install(int idHook, IntPtr windowHandle, IntPtr delegatePointer);

    // ...
    
    protected readonly GCHandle garbageCollectorHandle;
    
    public KeyboardHook()
    {
        instance = IntPtr.Zero;
        handler = new HookCallback(Callback);
        garbageCollectorHandle = GCHandle.Alloc(handler); // Or GC.KeepAlive(handler)
    }
    
    ~KeyboardHook()
    {
        garbageCollectorHandle.Free();
    }
    
    public void Install(Process process)
    {
        IntPtr delegatePointer = Marshal.GetFunctionPointerForDelegate(handler);
        
        instance = Install(WH_KEYBOARD, process.MainWindowHandle, delegatePointer);
    }
    
    // ...
}

直接在SetWindowsHookExA (C++) 中使用handler ：

HHOOK Install(int idHook, HWND window, HOOKPROC hookCallback)
{
    auto processId = 0ul;
    auto threadId = GetWindowThreadProcessId(window, &processId);

    _hookCallback = hookCallback;

    return SetWindowsHookExA(idHook, hookCallback, _moduleHandle, threadId);
}

Answer 1

C# 代码调用 DLL 的Install() function 并翻转了第二个和第三个参数。

更改此行：

instance = Install(WH_KEYBOARD, handler, process.MainWindowHandle);

对此：

instance = Install(WH_KEYBOARD, process.MainWindowHandle, handler);

更新：此外，您没有显示 C# 代码对 DLL 的Install() function 的声明。 但是在 C++ 代码中， Install() function 没有指定调用约定，因此它（可能，取决于编译器配置）默认为__cdecl （ HookProc()使用的是__stdcall调用约定）。 因此，请确保 C# 代码在导入Install() function 时指定了正确的调用约定。 C# delegate默认使用__stdcall 。

Answer 2

该进程因访问无效的 memory 地址而终止。

每个 Windows 进程都有不同的虚拟 memory区域。 In other words, the 0x1234 memory address within the process A does not point to the same value/function as 0x1234 memory address within the process B , since 0x1234 is a virtual memory address bound to it's corresponding process.

为了实现 C++ DLL 和 C# 应用程序（任何不同的进程）之间的通信，需要进程间通信(IPC)。

对于那些对这个特定案例感兴趣的人，我最终创建了一个不可见的虚拟 window作为通过来自 DLL 的SendMessage调用接收消息的中心点。