First version of Miio library

.editorconfig

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+root = true
+
+[*]
+indent_style = tab
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[*.md]
+trim_trailing_whitespace = false
+
+[package.json]
+indent_style = space
+indent_size = 2

.eslintrc

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+{
+  "plugins": [ "node" ],
+  "extends": [ "eslint:recommended", "plugin:node/recommended" ],
+  "env": {},
+  "ecmaFeatures": {},
+  "globals": {},
+  "rules": {
+    "node/no-unsupported-features": [
+      "error",
+      {
+        "version": 6
+      }
+    ],
+    "no-irregular-whitespace": 2,
+    "quotes": [
+      2,
+      "single"
+    ]
+  }
+}

.gitignore

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+node_modules
+npm-debug.log

example.js

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+'use strict';
+
+const { Device } = require('./index');
+
+// Create a new device over the given address
+const device = new Device('192.168.100.8');
+
+// Call any method via call
+device.call('set_mode', [ 'silent' ])
+	.then(console.log)
+	.catch(console.error);
+
+// Or use some of the built-in methods
+device.setPower(false);
+
+device.getProperties([ 'power', 'mode', 'aqi', 'temp_dec', 'humidity' ])
+	.then(console.log)
+	.catch(console.error);

index.js

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+'use strict';
+
+const dgram = require('dgram');
+const Packet = require('./packet');
+
+class Device {
+	constructor(address) {
+		this.address = address;
+
+		this.packet = new Packet();
+		this.socket = dgram.createSocket('udp4');
+		this.socket.on('message', this._onMessage.bind(this));
+
+		this._id = 0;
+		this._promises = {};
+	}
+
+	_onMessage(msg) {
+		this.packet.raw = msg;
+
+		if(this._tokenResolve) {
+			this.packet.token = this.packet.checksum;
+			this._tokenResolve();
+			this._lastToken = Date.now();
+			this._tokenResolve = null;
+			this._tokenPromise = null;
+		} else {
+			let str = this.packet.data.toString('utf8');
+			let object = JSON.parse(str);
+
+			const p = this._promises[object.id];
+			if(! p) return;
+			if(object.result) {
+				p.resolve(object.result);
+			} else {
+				p.reject(object.error);
+			}
+
+			delete this._promises[object.id];
+		}
+	}
+
+	_ensureToken() {
+		if(this._lastToken > Date.now() - 60000) {
+			return Promise.resolve();
+		}
+
+		if(this._tokenPromise) {
+			return this._tokenPromise;
+		}
+
+		this._tokenPromise = new Promise((resolve, reject) => {
+			const data = this.packet.raw;
+			this.socket.send(data, 0, data.length, 54321, this.address, err => err && reject(err));
+			this._tokenResolve = resolve;
+		});
+		return this._tokenPromise;
+	}
+
+	call(method, params) {
+		return this._ensureToken()
+			.then(() => {
+				this._id = this._id == 10000 ? 1 : this._id + 1;
+				this.packet.data = Buffer.from(JSON.stringify({
+					id: this._id,
+					method: method,
+					params: params
+				}), 'utf8');
+
+				const data = this.packet.raw;
+
+				return new Promise((resolve, reject) => {
+					this._promises[this._id] = {
+						resolve: resolve,
+						reject: reject
+					};
+
+					this.socket.send(data, 0, data.length, 54321, this.address, err => err && reject(err));
+				});
+			});
+	}
+
+	setPower(on) {
+		return this.call('set_power', [ on ? 'on' : 'off '])
+			.then(() => on);
+	}
+
+	getProperties(props) {
+		return this.call('get_prop', props)
+			.then(result => {
+				const obj = {};
+				for(let i=0; i<result.length; i++) {
+					obj[props[i]] = result[i];
+				}
+				return obj;
+			});
+	}
+}
+
+module.exports.Device = Device;

package.json

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+{
+  "name": "miio",
+  "version": "0.1.0",
+  "license": "MIT",
+  "description": "Library for controlling MIIO devices such as the Mi Air Purifier",
+  "repository": "aholstenson/miio",
+  "main": "lib/index.js",
+  "keywords": [
+    "xiaomi",
+    "mi",
+    "miio"
+  ],
+  "scripts": {
+    "prepublish": "node_modules/.bin/eslint lib",
+    "test": "node_modules/.bin/eslint lib"
+  },
+  "dependencies": {
+  },
+  "devDependencies": {
+    "eslint": "^3.11.1",
+    "eslint-plugin-node": "^3.0.5"
+  }
+}

packet.js

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+'use strict';
+
+const crypto = require('crypto');
+
+class Packet {
+	constructor() {
+		this.header = Buffer.alloc(2 + 2 + 4 + 4 + 4 + 16);
+		this.header[0] = 0x21;
+		this.header[1] = 0x31;
+
+		for(let i=4; i<32; i++) {
+			this.header[i] = 0xff;
+		}
+	}
+
+	handshake() {
+		this.data = null;
+	}
+
+	get raw() {
+		if(this.data) {
+			if(! this._token) {
+				throw new Error('Token is required to send commands');
+			}
+
+			// Encrypt the data
+			let cipher = crypto.createCipheriv('aes-128-cbc', this._tokenKey, this._tokenIV);
+			let encrypted = Buffer.concat([
+				cipher.update(this.data),
+				cipher.final()
+			]);
+
+			// Set the length
+			this.header.writeInt16BE(32 + encrypted.length, 2);
+
+			// Calculate the checksum
+			let digest = crypto.createHash('md5')
+				.update(this.header.slice(0, 16))
+				.update(this._token)
+				.update(encrypted)
+				.digest();
+			digest.copy(this.header, 16);
+
+			return Buffer.concat([ this.header, encrypted ]);
+		} else {
+			this.header.writeInt16BE(32, 2);
+
+			for(let i=4; i<32; i++) {
+				this.header[i] = 0xff;
+			}
+
+			return this.header;
+		}
+	}
+
+	set raw(msg) {
+		this.header = msg.slice(0, 32);
+		const encrypted = msg.slice(32);
+		if(encrypted.length > 0) {
+			let decipher = crypto.createDecipheriv('aes-128-cbc', this._tokenKey, this._tokenIV);
+			this.data = Buffer.concat([
+				decipher.update(encrypted),
+				decipher.final()
+			]);
+		}
+	}
+
+	get token() {
+		return this._token;
+	}
+
+	set token(t) {
+		this._token = t;
+		this._tokenKey = crypto.createHash('md5').update(t).digest();
+		this._tokenIV = crypto.createHash('md5').update(this._tokenKey).update(t).digest();
+	}
+
+	get checksum() {
+		return this.header.slice(16);
+	}
+}
+
+module.exports = Packet;