Merge pull request mqttjs#841 from Degola/master

mcollina · web-flow · commit 83f3b3d30fc0 · 2018-07-19T15:13:42.000+02:00
Solves issue mqttjs#810
diff --git a/lib/client.js b/lib/client.js
@@ -120,8 +120,11 @@ function MqttClient (streamBuilder, options) {
   this.connackTimer = null
   // Reconnect timer
   this.reconnectTimer = null
-  // MessageIDs starting with 1
-  this.nextId = Math.floor(Math.random() * 65535)
+  /**
+   * MessageIDs starting with 1
+   * ensure that nextId is min. 1, see https://github.com/mqttjs/MQTT.js/issues/810
+   */
+  this.nextId = Math.max(1, Math.floor(Math.random() * 65535))
 
   // Inflight callbacks
   this.outgoing = {}
@@ -1070,18 +1073,21 @@ MqttClient.prototype._handlePubrel = function (packet, callback) {
 
 /**
  * _nextId
+ * @return unsigned int
  */
 MqttClient.prototype._nextId = function () {
+  // id becomes current state of this.nextId and increments afterwards
   var id = this.nextId++
-  // Ensure 16 bit unsigned int:
-  if (id === 65535) {
+  // Ensure 16 bit unsigned int (max 65535, nextId got one higher)
+  if (this.nextId === 65536) {
     this.nextId = 1
   }
   return id
 }
 
 /**
  * getLastMessageId
+ * @return unsigned int
  */
 MqttClient.prototype.getLastMessageId = function () {
   return (this.nextId === 1) ? 65535 : (this.nextId - 1)
