[issue #84] Fix and unit test added

src/TinyMqtt.cpp

@@ -646,6 +646,7 @@ void MqttClient::processMessage(MqttMessage* mesg)
       if (mqtt_connected() or tcp_client == nullptr)
       {
         uint8_t qos = mesg->flags();
+        qos = (qos / 2) & 3;
         payload = header;
         mesg->getString(payload, len);
         Topic published(payload, len);
@@ -654,8 +655,19 @@ void MqttClient::processMessage(MqttMessage* mesg)
           Console << "Received Publish (" << published.str().c_str() << ") size=" << (int)len << endl;
         #endif
         // << '(' << string(payload, len).c_str() << ')'  << " msglen=" << mesg->length() << endl;
-        if (qos) payload+=2;  // ignore packet identifier if any
+        const char* ID;     // remove PublishID() to avoid misuse
+        if (qos) {
+          ID = payload;
+          payload+=2;  // ignore packet identifier if any
+        }
         len=mesg->end()-payload;
+        if (qos == 1)
+        {
+          MqttMessage msg(MqttMessage::Type::PubAck);
+          msg.add(ID[0]);  // MessageID high
+          msg.add(ID[1]);  // MessageID low
+          msg.sendTo(this);
+        }
         // TODO reset DUP
         // TODO reset RETAIN