问题描述
This is simple Windows C++ keylogger example
当我在 Visual Studio 中运行它时，HookCallback 被正确调用。
我想在 Node.js 中使用 node-addon-api 做同样的事情，但我不想在文件中记录按键，我想使用回调将键码值发送到 JavaScript 世界。
Here's my repository。这就是我正在做的...
JavaScript
const addon = require("bindings")("push_to_talk");
addon.start((keyCode) => {
console.log("key is pressed:",keyCode);
});
console.log("testing...");
原生
#include <Windows.h>
#include <napi.h>
#include <time.h>
#include <cstdio>
#include <fstream>
#include <iostream>
#include <sstream>
// Declare the TSFN
Napi::ThreadSafeFunction tsfn;
// Create a native callback function to be invoked by the TSFN
auto callback = [](Napi::Env env,Napi::Function jsCallback,int* value) {
// Call the JS callback
jsCallback.Call({Napi::Number::New(env,*value)});
// We're finished with the data.
delete value;
};
// variable to store the HANDLE to the hook. Don't declare it anywhere else then globally
// or you will get problems since every function uses this variable.
HHOOK _hook;
// This struct contains the data received by the hook callback. As you see in the callback function
// it contains the thing you will need: vkCode = virtual key code.
KBDLLHOOKSTRUCT kbdStruct;
// Trigger the JS callback when a key is pressed
void Start(const Napi::CallbackInfo& info) {
std::cout << "Start is called" << std::endl;
Napi::Env env = info.Env();
// Create a ThreadSafeFunction
tsfn = Napi::ThreadSafeFunction::New(
env,info[0].As<Napi::Function>(),// JavaScript function called asynchronously
"Keyboard Events",// Name
0,// Unlimited queue
1 // Only one thread will use this initially
);
}
// This is the callback function. Consider it the event that is raised when,in this case,// a key is pressed.
LRESULT __stdcall HookCallback(int nCode,WParaM wParam,LParaM lParam) {
std::cout << "HookCallback is called" << std::endl;
if (nCode >= 0) {
// the action is valid: HC_ACTION.
if (wParam == WM_KEYDOWN) {
// lParam is the pointer to the struct containing the data needed,so cast and assign it
// to kdbStruct.
kbdStruct = *((KBDLLHOOKSTRUCT*)lParam);
// Send (kbdStruct.vkCode) to JS world via "start" function callback parameter
int* value = new int(kbdStruct.vkCode);
napi_status status = tsfn.BlockingCall(value,callback);
if (status != napi_ok) {
std::cout << "BlockingCall is not ok" << std::endl;
}
}
}
// call the next hook in the hook chain. This is nessecary or your hook chain will break and the
// hook stops
return CallNextHookEx(_hook,nCode,wParam,lParam);
}
void SetHook() {
std::cout << "SetHook is called" << std::endl;
// Set the hook and set it to use the callback function above
// WH_KEYBOARD_LL means it will set a low level keyboard hook. More @R_942_4045@ion about it at
// MSDN. The last 2 parameters are NULL,0 because the callback function is in the same thread
// and window as the function that sets and releases the hook.
if (!(_hook = SetwindowsHookEx(WH_KEYBOARD_LL,HookCallback,NULL,0))) {
LPCSTR a = "Failed to install hook!";
LPCSTR b = "Error";
MessageBox(NULL,a,b,MB_ICONERROR);
}
}
Napi::Object Init(Napi::Env env,Napi::Object exports) {
exports.Set(Napi::String::New(env,"start"),Napi::Function::New(env,Start));
// set the hook
SetHook();
return exports;
}
NODE_API_MODULE(push_to_talk,Init)
但是，在我的例子中，HookCallback 永远不会被调用（HookCallback is called 消息永远不会被打印），当我点击键盘时，点击速度会减慢，并且我遭受了一些非常明显的延迟原因。
更新：根据LowLevelKeyboardProc documentation：“这个钩子是在安装它的线程的上下文中调用的。调用是通过向安装钩子的线程发送消息来进行的. 因此，安装钩子的线程必须有消息循环。"
我尝试在这样的循环中调用 GetMessage
Napi::Object Init(Napi::Env env,Start));
// set the hook
SetHook();
MSG msg;
BOOL bRet;
while ((bRet = GetMessage(&msg,0)) != 0) {
if (bRet == -1) {
// handle the error and possibly exit
} else {
TranslateMessage(&msg);
dispatchMessage(&msg);
}
}
return exports;
}
但这会阻塞 JavaScript 线程。此外，现在按下键盘按钮时，实际上会打印调试消息 HookCallback is called，但随后在此行 while ((bRet = GetMessage(&msg,0)) != 0)...
$ node .
SetHook is called
HookCallback is called
C:\Windows\SYstem32\cmd.exe - node .[10888]: c:\ws\src\node_api.cc:1078: Assertion `(func) != nullptr' Failed.
1: 77201783 RegisterlogonProcess+3427
2: 77DC537D KiUserCallbackdispatcher+77
3: 607007B9 Init+521 [c:\users\aabuhijleh\desktop\projects\testing\push-to-talk\src\push-to-talk.cc]:L93
解决方法
通过在单独的线程中创建消息循环，我能够使其正常工作here
// Trigger the JS callback when a key is pressed
void Start(const Napi::CallbackInfo& info) {
std::cout << "Start is called" << std::endl;
Napi::Env env = info.Env();
// Create a ThreadSafeFunction
tsfn = Napi::ThreadSafeFunction::New(
env,info[0].As<Napi::Function>(),// JavaScript function called asynchronously
"Keyboard Events",// Name
0,// Unlimited queue
1,// Only one thread will use this initially
[](Napi::Env) { // Finalizer used to clean threads up
nativeThread.join();
});
nativeThread = std::thread([] {
// This is the callback function. Consider it the event that is raised when,in this case,// a key is pressed.
static auto HookCallback = [](int nCode,WPARAM wParam,LPARAM lParam) -> LRESULT {
if (nCode >= 0) {
// the action is valid: HC_ACTION.
if (wParam == WM_KEYDOWN) {
// lParam is the pointer to the struct containing the data needed,so cast and
// assign it to kdbStruct.
kbdStruct = *((KBDLLHOOKSTRUCT*)lParam);
// Send (kbdStruct.vkCode) to JS world via "start" function callback parameter
int* value = new int(kbdStruct.vkCode);
napi_status status = tsfn.BlockingCall(value,callback);
if (status != napi_ok) {
std::cout << "BlockingCall is not ok" << std::endl;
}
}
}
// call the next hook in the hook chain. This is nessecary or your hook chain will
// break and the hook stops
return CallNextHookEx(_hook,nCode,wParam,lParam);
};
// Set the hook and set it to use the callback function above
// WH_KEYBOARD_LL means it will set a low level keyboard hook. More information about it at
// MSDN. The last 2 parameters are NULL,0 because the callback function is in the same
// thread and window as the function that sets and releases the hook.
if (!(_hook = SetWindowsHookEx(WH_KEYBOARD_LL,HookCallback,NULL,0))) {
LPCSTR a = "Failed to install hook!";
LPCSTR b = "Error";
MessageBox(NULL,a,b,MB_ICONERROR);
}
// Create a message loop
MSG msg;
BOOL bRet;
while ((bRet = GetMessage(&msg,0)) != 0) {
if (bRet == -1) {
// handle the error and possibly exit
} else {
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}
});
}
现在，当按下键盘时，JavaScript 回调会被正确调用。