mirror of
https://github.com/xinnan-tech/xiaozhi-esp32-server.git
synced 2026-07-29 18:23:59 +08:00
mqtt gateway project
This commit is contained in:
marlonz
@@ -0,0 +1,499 @@
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const debug = require('debug')('mqtt-server');
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const EventEmitter = require('events');
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// MQTT 固定头部的类型
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const PacketType = {
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CONNECT: 1,
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CONNACK: 2,
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PUBLISH: 3,
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SUBSCRIBE: 8,
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SUBACK: 9,
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PINGREQ: 12,
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PINGRESP: 13,
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DISCONNECT: 14 // 添加 DISCONNECT
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};
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/**
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* MQTT协议处理类
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* 负责MQTT协议的解析和封装，以及心跳维持
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*/
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class MQTTProtocol extends EventEmitter {
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constructor(socket) {
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super();
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this.socket = socket;
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this.buffer = Buffer.alloc(0);
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this.isConnected = false;
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this.keepAliveInterval = 0;
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this.lastActivity = Date.now();
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this.setupSocketHandlers();
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}
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/**
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* 设置Socket事件处理
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*/
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setupSocketHandlers() {
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this.socket.on('data', (data) => {
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this.lastActivity = Date.now();
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this.buffer = Buffer.concat([this.buffer, data]);
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this.processBuffer();
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});
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this.socket.on('close', () => {
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this.emit('close');
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});
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this.socket.on('error', (err) => {
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this.emit('error', err);
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});
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}
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/**
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* 处理缓冲区中的所有完整消息
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*/
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processBuffer() {
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// 持续处理缓冲区中的数据，直到没有完整的消息可以处理
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while (this.buffer.length > 0) {
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// 至少需要2个字节才能开始解析（1字节固定头部 + 至少1字节的剩余长度）
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if (this.buffer.length < 2) return;
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try {
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// 获取消息类型
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const firstByte = this.buffer[0];
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const type = (firstByte >> 4);
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// 解析剩余长度
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const { value: remainingLength, bytesRead } = this.decodeRemainingLength(this.buffer);
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// 计算整个消息的长度
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const messageLength = 1 + bytesRead + remainingLength;
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// 检查缓冲区中是否有完整的消息
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if (this.buffer.length < messageLength) {
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// 消息不完整，等待更多数据
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return;
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}
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// 提取完整的消息
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const message = this.buffer.subarray(0, messageLength);
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if (!this.isConnected && type !== PacketType.CONNECT) {
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debug('未连接时收到非CONNECT消息，关闭连接');
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this.socket.end();
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return;
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}
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// 根据消息类型处理
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switch (type) {
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case PacketType.CONNECT:
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this.parseConnect(message);
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break;
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case PacketType.PUBLISH:
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this.parsePublish(message);
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break;
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case PacketType.SUBSCRIBE:
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this.parseSubscribe(message);
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break;
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case PacketType.PINGREQ:
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this.parsePingReq(message);
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break;
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case PacketType.DISCONNECT:
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this.parseDisconnect(message);
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break;
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default:
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debug('未处理的包类型:', type, message);
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this.emit('protocolError', new Error(`未处理的包类型: ${type}`));
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}
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// 从缓冲区中移除已处理的消息
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this.buffer = this.buffer.subarray(messageLength);
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} catch (err) {
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// 如果解析出错，可能是数据不完整，等待更多数据
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if (err.message === 'Malformed Remaining Length') {
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return;
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}
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// 其他错误可能是协议错误，清空缓冲区并发出错误事件
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this.buffer = Buffer.alloc(0);
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this.emit('protocolError', err);
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return;
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}
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}
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}
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/**
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* 解析MQTT报文中的Remaining Length字段
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* @param {Buffer} buffer - 消息缓冲区
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* @returns {{value: number, bytesRead: number}} 包含解析的值和读取的字节数
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*/
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decodeRemainingLength(buffer) {
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let multiplier = 1;
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let value = 0;
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let bytesRead = 0;
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let digit;
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do {
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if (bytesRead >= 4 || bytesRead >= buffer.length - 1) {
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throw new Error('Malformed Remaining Length');
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}
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digit = buffer[bytesRead + 1];
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bytesRead++;
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value += (digit & 127) * multiplier;
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multiplier *= 128;
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} while ((digit & 128) !== 0);
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return { value, bytesRead };
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}
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/**
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* 编码MQTT报文中的Remaining Length字段
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* @param {number} length - 要编码的长度值
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* @returns {{bytes: Buffer, bytesLength: number}} 包含编码后的字节和字节长度
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*/
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encodeRemainingLength(length) {
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let digit;
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const bytes = Buffer.alloc(4); // 最多4个字节
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let bytesLength = 0;
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do {
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digit = length % 128;
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length = Math.floor(length / 128);
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// 如果还有更多字节，设置最高位
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if (length > 0) {
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digit |= 0x80;
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}
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bytes[bytesLength++] = digit;
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} while (length > 0 && bytesLength < 4);
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return { bytes, bytesLength };
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}
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/**
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* 解析CONNECT消息
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* @param {Buffer} message - 完整的CONNECT消息
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*/
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parseConnect(message) {
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// 解析剩余长度
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const { value: remainingLength, bytesRead } = this.decodeRemainingLength(message);
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// 固定头部之后的位置 (MQTT固定头部第一个字节 + Remaining Length字段的字节)
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const headerLength = 1 + bytesRead;
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// 从可变头部开始位置读取协议名长度
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const protocolLength = message.readUInt16BE(headerLength);
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const protocol = message.toString('utf8', headerLength + 2, headerLength + 2 + protocolLength);
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// 更新位置指针，跳过协议名
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let pos = headerLength + 2 + protocolLength;
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// 协议级别，4为MQTT 3.1.1
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const protocolLevel = message[pos];
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// 检查协议版本
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if (protocolLevel !== 4) { // 4 表示 MQTT 3.1.1
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debug('不支持的协议版本:', protocolLevel);
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// 发送 CONNACK，使用不支持的协议版本的返回码 (0x01)
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this.sendConnack(1, false);
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// 关闭连接
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this.socket.end();
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return;
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}
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pos += 1;
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// 连接标志
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const connectFlags = message[pos];
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const hasUsername = (connectFlags & 0x80) !== 0;
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const hasPassword = (connectFlags & 0x40) !== 0;
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const cleanSession = (connectFlags & 0x02) !== 0;
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pos += 1;
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// 保持连接时间
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const keepAlive = message.readUInt16BE(pos);
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pos += 2;
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// 解析 clientId
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const clientIdLength = message.readUInt16BE(pos);
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pos += 2;
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const clientId = message.toString('utf8', pos, pos + clientIdLength);
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pos += clientIdLength;
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// 解析 username（如果存在）
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let username = '';
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if (hasUsername) {
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const usernameLength = message.readUInt16BE(pos);
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pos += 2;
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username = message.toString('utf8', pos, pos + usernameLength);
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pos += usernameLength;
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}
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// 解析 password（如果存在）
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let password = '';
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if (hasPassword) {
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const passwordLength = message.readUInt16BE(pos);
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pos += 2;
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password = message.toString('utf8', pos, pos + passwordLength);
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pos += passwordLength;
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}
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// 设置心跳间隔（客户端指定的keepAlive值的1.5倍，单位为秒）
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this.keepAliveInterval = keepAlive * 1000 * 1.5;
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// 发送 CONNACK
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this.sendConnack(0, false);
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// 标记为已连接
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this.isConnected = true;
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// 发出连接事件
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this.emit('connect', {
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clientId,
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protocol,
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protocolLevel,
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keepAlive,
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username,
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password,
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cleanSession
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});
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}
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/**
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* 解析PUBLISH消息
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* @param {Buffer} message - 完整的PUBLISH消息
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*/
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parsePublish(message) {
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// 从第一个字节中提取QoS级别(bits 1-2)
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const firstByte = message[0];
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const qos = (firstByte & 0x06) >> 1; // 0x06 是二进制 00000110，用于掩码提取QoS位
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const dup = (firstByte & 0x08) !== 0; // 0x08 是二进制 00001000，用于掩码提取DUP标志
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const retain = (firstByte & 0x01) !== 0; // 0x01 是二进制 00000001，用于掩码提取RETAIN标志
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// 使用通用方法解析剩余长度
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const { value: remainingLength, bytesRead } = this.decodeRemainingLength(message);
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// 固定头部之后的位置 (MQTT固定头部第一个字节 + Remaining Length字段的字节)
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const headerLength = 1 + bytesRead;
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// 解析主题
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const topicLength = message.readUInt16BE(headerLength);
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const topic = message.toString('utf8', headerLength + 2, headerLength + 2 + topicLength);
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// 对于QoS > 0，包含消息ID
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let packetId = null;
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let payloadStart = headerLength + 2 + topicLength;
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if (qos > 0) {
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packetId = message.readUInt16BE(payloadStart);
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payloadStart += 2;
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}
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// 解析有效载荷
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const payload = message.slice(payloadStart).toString('utf8');
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// 发出发布事件
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this.emit('publish', {
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topic,
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payload,
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qos,
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dup,
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retain,
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packetId
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});
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}
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/**
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* 解析SUBSCRIBE消息
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* @param {Buffer} message - 完整的SUBSCRIBE消息
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*/
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parseSubscribe(message) {
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const packetId = message.readUInt16BE(2);
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const topicLength = message.readUInt16BE(4);
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const topic = message.toString('utf8', 6, 6 + topicLength);
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const qos = message[6 + topicLength]; // QoS值
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// 发出订阅事件
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this.emit('subscribe', {
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packetId,
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topic,
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qos
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});
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}
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/**
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* 解析PINGREQ消息
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* @param {Buffer} message - 完整的PINGREQ消息
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*/
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parsePingReq(message) {
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debug('收到心跳请求');
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// 发送 PINGRESP
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this.sendPingResp();
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debug('已发送心跳响应');
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}
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/**
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* 解析DISCONNECT消息
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* @param {Buffer} message - 完整的DISCONNECT消息
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*/
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parseDisconnect(message) {
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// 标记为未连接
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this.isConnected = false;
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// 发出断开连接事件
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this.emit('disconnect');
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// 关闭 socket
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this.socket.end();
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}
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/**
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* 发送CONNACK消息
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* @param {number} returnCode - 返回码
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* @param {boolean} sessionPresent - 会话存在标志
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*/
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sendConnack(returnCode = 0, sessionPresent = false) {
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if (!this.socket.writable) return;
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const packet = Buffer.from([
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PacketType.CONNACK << 4,
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2, // Remaining length
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sessionPresent ? 1 : 0, // Connect acknowledge flags
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returnCode // Return code
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]);
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this.socket.write(packet);
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}
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/**
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* 发送PUBLISH消息
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* @param {string} topic - 主题
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* @param {string} payload - 有效载荷
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* @param {number} qos - QoS级别
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* @param {boolean} dup - 重复标志
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* @param {boolean} retain - 保留标志
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* @param {number} packetId - 包ID（仅QoS > 0时需要）
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*/
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sendPublish(topic, payload, qos = 0, dup = false, retain = false, packetId = null) {
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if (!this.isConnected || !this.socket.writable) return;
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const topicLength = Buffer.byteLength(topic);
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const payloadLength = Buffer.byteLength(payload);
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// 计算剩余长度
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let remainingLength = 2 + topicLength + payloadLength;
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// 如果QoS > 0，需要包含包ID
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if (qos > 0 && packetId) {
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remainingLength += 2;
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}
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// 编码可变长度
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const { bytes: remainingLengthBytes, bytesLength: remainingLengthSize } = this.encodeRemainingLength(remainingLength);
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// 分配缓冲区：固定头部(1字节) + 可变长度字段 + 剩余长度值
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const packet = Buffer.alloc(1 + remainingLengthSize + remainingLength);
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// 写入固定头部
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||||
let firstByte = PacketType.PUBLISH << 4;
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if (dup) firstByte |= 0x08;
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if (qos > 0) firstByte |= (qos << 1);
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||||
if (retain) firstByte |= 0x01;
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||||
|
||||
packet[0] = firstByte;
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||||
|
||||
// 写入可变长度字段
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remainingLengthBytes.copy(packet, 1, 0, remainingLengthSize);
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||||
|
||||
// 写入主题长度和主题
|
||||
const variableHeaderStart = 1 + remainingLengthSize;
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packet.writeUInt16BE(topicLength, variableHeaderStart);
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packet.write(topic, variableHeaderStart + 2);
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||||
|
||||
// 如果QoS > 0，写入包ID
|
||||
let payloadStart = variableHeaderStart + 2 + topicLength;
|
||||
if (qos > 0 && packetId) {
|
||||
packet.writeUInt16BE(packetId, payloadStart);
|
||||
payloadStart += 2;
|
||||
}
|
||||
|
||||
// 写入有效载荷
|
||||
packet.write(payload, payloadStart);
|
||||
|
||||
this.socket.write(packet);
|
||||
this.lastActivity = Date.now();
|
||||
}
|
||||
|
||||
/**
|
||||
* 发送SUBACK消息
|
||||
* @param {number} packetId - 包ID
|
||||
* @param {number} returnCode - 返回码
|
||||
*/
|
||||
sendSuback(packetId, returnCode = 0) {
|
||||
if (!this.isConnected || !this.socket.writable) return;
|
||||
|
||||
const packet = Buffer.from([
|
||||
PacketType.SUBACK << 4,
|
||||
3, // Remaining length
|
||||
packetId >> 8, // Packet ID MSB
|
||||
packetId & 0xFF, // Packet ID LSB
|
||||
returnCode // Return code
|
||||
]);
|
||||
|
||||
this.socket.write(packet);
|
||||
this.lastActivity = Date.now();
|
||||
}
|
||||
|
||||
/**
|
||||
* 发送PINGRESP消息
|
||||
*/
|
||||
sendPingResp() {
|
||||
if (!this.isConnected || !this.socket.writable) return;
|
||||
|
||||
const packet = Buffer.from([
|
||||
PacketType.PINGRESP << 4, // Fixed header
|
||||
0 // Remaining length
|
||||
]);
|
||||
|
||||
this.socket.write(packet);
|
||||
this.lastActivity = Date.now();
|
||||
}
|
||||
|
||||
/**
|
||||
* 获取上次活动时间
|
||||
*/
|
||||
getLastActivity() {
|
||||
return this.lastActivity;
|
||||
}
|
||||
|
||||
/**
|
||||
* 获取心跳间隔
|
||||
*/
|
||||
getKeepAliveInterval() {
|
||||
return this.keepAliveInterval;
|
||||
}
|
||||
|
||||
/**
|
||||
* 清空缓冲区
|
||||
*/
|
||||
clearBuffer() {
|
||||
this.buffer = Buffer.alloc(0);
|
||||
}
|
||||
|
||||
/**
|
||||
* 关闭连接
|
||||
*/
|
||||
close() {
|
||||
if (this.socket.writable) {
|
||||
this.socket.end();
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// 导出 PacketType 和 MQTTProtocol 类
|
||||
module.exports = {
|
||||
PacketType,
|
||||
MQTTProtocol
|
||||
};
|
||||
Reference in New Issue
Block a user