feat: mqtt alerts (#538)

src/notification/mqtt.ts

@@ -0,0 +1,107 @@
+import {Link, Store} from '../store/model';
+import MqttClient, {IClientOptions, IClientPublishOptions} from 'mqtt';
+import {Print, logger} from '../logger';
+import {config} from '../config';
+
+const mqtt = config.notifications.mqtt;
+let client: MqttClient.Client;
+
+if (mqtt.broker) {
+	if (checkInsecureUsage(mqtt.password, mqtt.broker)) {
+		logger.warn('✖ Insecure transport of password - Only use credentials with MQTT brokers on private networks.');
+	} else {
+		const clientOptions: IClientOptions = {
+			clean: (mqtt.clientId === ''),
+			clientId: mqtt.clientId === '' ? undefined : mqtt.clientId,
+			password: mqtt.password === '' ? undefined : mqtt.password,
+			username: mqtt.username === '' ? undefined : mqtt.username
+		};
+		client = MqttClient.connect(`mqtt://${mqtt.broker}:${mqtt.port}`, clientOptions);
+	}
+}
+
+export function sendMqttMessage(link: Link, store: Store) {
+	if (client) {
+		logger.debug('↗ sending mqtt message');
+
+		(async () => {
+			const givenUrl = link.cartUrl ? link.cartUrl : link.url;
+			const message = `{"msg":"${Print.inStock(link, store)}", "url":"${givenUrl}"}`;
+			const topic = generateTopic(link, store, mqtt.topic);
+			const pubOptions: IClientPublishOptions = {
+				qos: mqtt.qos as 0 | 1 | 2,
+				retain: false
+			};
+
+			try {
+				client.publish(
+					topic,
+					message,
+					pubOptions
+				);
+				logger.info('✔ mqtt message sent');
+			} catch (error) {
+				logger.error('✖ couldn\'t send mqtt message', error);
+			}
+		})();
+	}
+}
+
+function generateTopic(link: Link, store: Store, topic: string): string {
+	topic.trim();
+	topic = topic.replace(/^\//, '');
+	topic = topic.replace(/%series%/g, link.series)
+		.replace(/%brand%/g, link.brand)
+		.replace(/%model%/g, link.model)
+		.replace(/%store%/g, store.name);
+
+	return topic;
+}
+
+/**
+ * Basic protection against sending credentials in the clear over public networks.
+ *	- Returns 'true' if password is supplied in .env but address/URL is not part of a private network
+ *	- Private networks evaluated:	Class A, B, or C private IP's or linklocal URL ("*.local")
+ *	- TLS could be implemented, however, the majority of MQTT services on the internet do not require user authentication.
+ *	- If you find a 'cloud' MQTT broker requiring authentication for publishing alerts, consider using another MQTT service (for now).
+ *
+ */
+function checkInsecureUsage(pass: string, address: string): boolean {
+	if (pass !== '') {
+		if (isClassANet(address) ||
+			isClassBNet(address) ||
+			isClassCNet(address) ||
+			isLinkLocal(address)) {
+			logger.debug(`MQTT using private network broker: ${address}`);
+		} else {
+			logger.debug(`MQTT using public network broker: ${address}`);
+			return true;
+		}
+	}
+
+	return false;
+}
+
+function isClassANet(address: string): boolean {
+	const classRegex = /^(10\.(\d|[1-9]\d|[12][0-5]{2})\.(\d|[1-9]\d|[12][0-5]{2})\.(\d|[1-9]\d|[12][0-5]{2}))$/;
+
+	return Boolean(classRegex.exec(address));
+}
+
+function isClassBNet(address: string): boolean {
+	const classRegex = /^(172\.(1[6-9]|2\d|3[01])\.(\d|[1-9]\d|[12][0-5]{2})\.(\d|[1-9]\d|[12][0-5]{2}))$/;
+
+	return Boolean(classRegex.exec(address));
+}
+
+function isClassCNet(address: string): boolean {
+	const classRegex = /^(192\.168\.(\d|[1-9]\d|[12][0-5]{2})\.(\d|[1-9]\d|[12][0-5]{2}))$/;
+
+	return Boolean(classRegex.exec(address));
+}
+
+function isLinkLocal(address: string): boolean {
+	const linkLocal = /.+\.local$/;
+
+	return Boolean(linkLocal.exec(address));
+}

src/notification/notification.ts

@@ -3,6 +3,7 @@ import {playSound} from './sound';
 import {sendDesktopNotification} from './desktop';
 import {sendDiscordMessage} from './discord';
 import {sendEmail} from './email';
+import {sendMqttMessage} from './mqtt';
 import {sendPushbulletNotification} from './pushbullet';
 import {sendPushoverNotification} from './pushover';
 import {sendSlackMessage} from './slack';
@@ -25,4 +26,5 @@ export function sendNotification(link: Link, store: Store) {
 	sendTelegramMessage(link, store);
 	sendTweet(link, store);
 	sendTwilioMessage(link, store);
+	sendMqttMessage(link, store);
 }