feat(mqtt5): implement re-authentication and handle auth success

src/lib/client.ts

@@ -433,6 +433,7 @@ export interface MqttClientEventCallbacks {
 	reconnect: VoidCallback
 	offline: VoidCallback
 	outgoingEmpty: VoidCallback
+	reauth: OnPacketCallback
 }
 
 /**
@@ -1678,6 +1679,66 @@ export default class MqttClient extends TypedEventEmitter<MqttClientEventCallbac
 		return this
 	}
 
+	/**
+	 * reauthenticate - MQTT 5.0 Re-authentication
+	 */
+	public reauthenticate(
+		reAuthOptions: Pick<
+			NonNullable<IAuthPacket['properties']>,
+			'authenticationData' | 'reasonString' | 'userProperties'
+		>,
+		callback?: PacketCallback,
+	): MqttClient {
+		let error: Error | null = null
+
+		if (this.options.protocolVersion !== 5) {
+			error = new Error(
+				'reauthenticate: this feature works only with mqtt-v5',
+			)
+		} else if (!this.connected) {
+			error = new Error('reauthenticate: client is not connected')
+		} else if (!reAuthOptions.authenticationData) {
+			error = new Error('reauthenticate: authenticationData is required')
+		}
+
+		const method = this.options.properties?.authenticationMethod
+
+		if (!error && !method) {
+			error = new Error(
+				'reauthenticate: authenticationMethod is required from initial CONNECT',
+			)
+		}
+
+		if (error) {
+			if (callback) {
+				callback(error)
+			}
+			this.emit('error', error)
+			return this
+		}
+
+		if (
+			reAuthOptions.authenticationData ===
+			this.options.properties.authenticationData
+		) {
+			this.log(
+				'reauthenticate: sending same authenticationData as initial connection',
+			)
+		}
+
+		const authPacket: IAuthPacket = {
+			cmd: 'auth',
+			reasonCode: 0x19,
+			properties: {
+				authenticationMethod: method,
+				...reAuthOptions,
+			},
+		}
+
+		this._sendPacket(authPacket, callback)
+		return this
+	}
+
 	/**
 	 * PRIVATE METHODS
 	 * =====================

src/lib/handlers/auth.ts

@@ -30,6 +30,10 @@ const handleAuth: PacketHandler = (
 			if (rc === 24) {
 				client.reconnecting = false
 				client['_sendPacket'](packet2)
+			} else if (rc === 0) {
+				if (client.connected) {
+					client.emit('reauth', packet)
+				}
 			} else {
 				const error = new ErrorWithReasonCode(
 					`Connection refused: ${ReasonCodes[rc]}`,

test/node/client_mqtt5.ts

@@ -1390,6 +1390,117 @@ describe('MQTT 5.0', () => {
 		},
 	)
 
+	it(
+		'should successfully reauthenticate with the broker',
+		{
+			timeout: 15000,
+		},
+		function (t, done) {
+			const port = ports.PORTAND103 + 92
+			const authMethod = 'GS-AUTH'
+
+			const testServer = serverBuilder('mqtt', (serverClient) => {
+				serverClient.on('connect', () => {
+					serverClient.connack({ reasonCode: 0 })
+				})
+
+				serverClient.on('auth', (packet) => {
+					if (packet.properties.authenticationMethod === authMethod) {
+						serverClient.auth({ reasonCode: 0 })
+					}
+				})
+			}).listen(port)
+
+			const client = mqtt.connect({
+				port: port,
+				protocolVersion: 5,
+				properties: {
+					authenticationMethod: authMethod,
+				},
+			})
+
+			client.on('connect', () => {
+				client.reauthenticate({
+					authenticationData: Buffer.from('initial-token'),
+				})
+			})
+
+			client.on('reauth', (packet: any) => {
+				assert.strictEqual(packet.reasonCode, 0)
+				client.end(true, () => testServer.close(done))
+			})
+		},
+	)
+
+	it(
+		'should emit an error if reauthenticate is called on a non-v5 connection',
+		{
+			timeout: 15000,
+		},
+		function (t, done) {
+			const port = ports.PORTAND103 + 90
+			const testServer = serverBuilder('mqtt', (serverClient) => {
+				serverClient.on('connect', () =>
+					serverClient.connack({ returnCode: 0 }),
+				)
+			}).listen(port)
+
+			const client = mqtt.connect({
+				port: port,
+				protocolVersion: 4,
+			})
+
+			client.on('error', (err) => {
+				try {
+					assert.ok(err.message.includes('works only with mqtt-v5'))
+					client.end(true, () => testServer.close(done))
+				} catch (assertErr) {
+					done(assertErr)
+				}
+			})
+
+			client.on('connect', () => {
+				client.reauthenticate({
+					authenticationData: Buffer.from('test'),
+				})
+			})
+		},
+	)
+
+	it(
+		'should emit an error if reauthenticate is called without an initial authenticationMethod',
+		{
+			timeout: 15000,
+		},
+		function (t, done) {
+			const port = ports.PORTAND103 + 91
+			const testServer = serverBuilder('mqtt', (serverClient) => {
+				serverClient.on('connect', () =>
+					serverClient.connack({ reasonCode: 0 }),
+				)
+			}).listen(port)
+
+			const client = mqtt.connect({
+				port: port,
+				protocolVersion: 5,
+				// Missing authenticationMethod
+			})
+
+			client.on('error', (err) => {
+				assert.ok(
+					err.message.includes('authenticationMethod is required'),
+				)
+				client.end(true, () => testServer.close(done))
+			})
+
+			client.on('connect', () => {
+				client.reauthenticate({
+					authenticationData: Buffer.from('test'),
+				})
+			})
+		},
+	)
+
 	it(
 		'pubrec handling custom invalid reason code',
 		{