MQTT client JWT refresh and set TLS to 1.2 (GoogleCloudPlatform#521)

Author: gguuss

iot/mqtt_example/cloudiot_mqtt_example_nodejs.js

@@ -67,6 +67,12 @@ var argv = require(`yargs`)
  requiresArg: true,
  type: 'number'
  },
+ token_exp_mins: {
+ default: 20,
+ description: 'Minutes to JWT token expiration.',
+ requiresArg: true,
+ type: 'number'
+ },
  mqtt_bridge_hostname: {
  default: 'mqtt.googleapis.com',
  description: 'MQTT bridge hostname.',
@@ -127,6 +133,31 @@ function publishAsync (messageCount, numMessages) {
  // If we have published fewer than numMessage messages, publish payload
  // messageCount + 1 in 1 second.
  setTimeout(function () {
+ let secsFromIssue = parseInt(Date.now() / 1000) - iatTime;
+ if (secsFromIssue > argv.token_exp_mins * 60) {
+ iatTime = parseInt(Date.now() / 1000);
+ console.log(`\tRefreshing token after ${secsFromIssue} seconds.`);
+
+ client.end();
+ connectionArgs.password = createJwt(argv.project_id, argv.private_key_file, argv.algorithm);
+ client = mqtt.connect(connectionArgs);
+
+ client.on('connect', () => {
+ console.log('connect', arguments);
+ });
+
+ client.on('close', () => {
+ console.log('close', arguments);
+ });
+
+ client.on('error', () => {
+ console.log('error', arguments);
+ });
+
+ client.on('packetsend', () => {
+ // Too verbose to log here
+ });
+ }
  publishAsync(messageCount + 1, numMessages);
  }, delayMs);
  } else {
@@ -146,17 +177,19 @@ const mqttClientId = `projects/${argv.project_id}/locations/${argv.cloud_region}
 // non-empty. The password field is used to transmit a JWT to authorize the
 // device. The "mqtts" protocol causes the library to connect using SSL, which
 // is required for Cloud IoT Core.
-const connectionArgs = {
+let connectionArgs = {
  host: argv.mqtt_bridge_hostname,
  port: argv.mqtt_bridge_port,
  clientId: mqttClientId,
  username: 'unused',
  password: createJwt(argv.project_id, argv.private_key_file, argv.algorithm),
- protocol: 'mqtts'
+ protocol: 'mqtts',
+ secureProtocol: 'TLSv1_2_method'
 };
 
 // Create a client, and connect to the Google MQTT bridge.
-const client = mqtt.connect(connectionArgs);
+let iatTime = parseInt(Date.now() / 1000);
+let client = mqtt.connect(connectionArgs);
 
 // The MQTT topic that this device will publish data to. The MQTT
 // topic name is required to be in the format below. The topic name must end in
@@ -180,7 +213,7 @@ client.on('error', () => {
 });
 
 client.on('packetsend', () => {
- console.log('packetsend', arguments);
+ // Note: logging packet send is very verbose
 });
 
 // Once all of the messages have been published, the connection to Google Cloud