n8n/packages/nodes-base/nodes/MQTT/GenericFunctions.ts

import { connectAsync, type IClientOptions, type MqttClient } from 'mqtt';
import { randomString } from 'n8n-workflow';
import { formatPrivateKey } from '@utils/utilities';

interface BaseMqttCredential {
	protocol: 'mqtt' | 'mqtts' | 'ws';
	host: string;
	port: number;
	username: string;
	password: string;
	clean: boolean;
	clientId: string;
	passwordless?: boolean;
}

type NonSslMqttCredential = BaseMqttCredential & {
	ssl: false;
};

type SslMqttCredential = BaseMqttCredential & {
	ssl: true;
	ca: string;
	cert: string;
	key: string;
	rejectUnauthorized?: boolean;
};
export type MqttCredential = NonSslMqttCredential | SslMqttCredential;

export const createClient = async (credentials: MqttCredential): Promise<MqttClient> => {
	const { protocol, host, port, clean, clientId, username, password } = credentials;

	const clientOptions: IClientOptions = {
		protocol,
		host,
		port,
		clean,
		clientId: clientId || `mqttjs_${randomString(8).toLowerCase()}`,
	};

	if (username && password) {
		clientOptions.username = username;
		clientOptions.password = password;
	}

	if (credentials.ssl) {
		clientOptions.ca = formatPrivateKey(credentials.ca);
		clientOptions.cert = formatPrivateKey(credentials.cert);
		clientOptions.key = formatPrivateKey(credentials.key);
		clientOptions.rejectUnauthorized = credentials.rejectUnauthorized;
	}

	return await connectAsync(clientOptions);
};