Minor improvements to parsing of MQTT CONNECT messages

collectagent/simplemqttservermessage.cpp

@@ -208,19 +208,23 @@ ssize_t SimpleMQTTMessage::receiveMessage(void* buf, size_t len)
           
           // Message is malformed, break out
           if(remainingLength < 12) {
-              break;
+              state = Error;
+          } else {
+              ssize_t idLen = ntohs(((uint16_t *) data)[0]);
+              data += 2;
+
+              // Leveraging the topic field to store also the client ID on CONNECT messages
+              if (idLen > 0) {
+                  topic = string(data, idLen);
+                  data += idLen;
+              } else {
+                  topic = "";
+              }
+
+              // We store the rest of the CONNECT payload in its raw form
+              payloadPtr = (void *) data;
+              payloadLength = remainingLength - ((uint8_t *) payloadPtr - (uint8_t *) remainingRaw);
           }
-          
-          ssize_t idLen = ntohs(((uint16_t*) data)[0]);
-          data+= 2;
-
-          // Leveraging the topic field to store also the client ID on CONNECT messages
-          topic = string(data, idLen);
-          data+= idLen;
-          
-          // We store the rest of the CONNECT payload in its raw form
-          payloadPtr = (void*) data;
-          payloadLength = remainingLength - ((uint8_t*)payloadPtr - (uint8_t*)remainingRaw);
           break;
       }
       case MQTT_PUBREL: {