Fixes minor MQTT bugs

* PubSubs sending more than one subscription at a time
* Subbing to topics, which are already subbed
* Checking the wrong topic list length, leading to no unsubbing

src/main/java/de/tu_darmstadt/tk/SmartHomeNetworkSim/core/protocols/MQTT_protocol.java

@@ -139,7 +139,8 @@ public class MQTT_protocol implements Protocol {
 				if(dest.getStatus()!=Port.CLOSED)
 					returnPackets.add(new MQTT_packet(MQTT_packet.PINGREQ, timestep, dest, port));
 			}
-		}else if(subs.contains(port)||pubSubs.contains(port)){
+		}
+		if(subs.contains(port)||pubSubs.contains(port)){
 			
 			//Subs can either subscribe to topics or unsubscribe
 			/**
@@ -152,17 +153,22 @@ public class MQTT_protocol implements Protocol {
 			 */
 			String newTopic;
 			//Subscribe if no subscriptions so far or not subscribed to all, with a probability of70%
-			if(tops.size()==0||(tops.size()!=subbedTopics.size()&&Math.random()<0.7)){
+			if(tops.size()==0||(tops.size()!=topics.size()&&Math.random()<0.7)){
 				//Forced Subscribe
-				newTopic = topics.get((int) Math.floor(Math.random()*topics.size()));
+				LinkedList<String> available = new LinkedList<String>();
+				available.addAll(topics);
+				available.removeAll(tops);
+				
+				newTopic = available.get((int) Math.floor(Math.random()*available.size()));
 				returnPackets.add(new MQTT_packet(MQTT_packet.SUBSCRIBE, timestep, port, broker, "topic:"+newTopic));
+				
 				if(broker.getStatus()!=Port.CLOSED){
 					timestep+=broker.getResponseTime();
 					returnPackets.add(new MQTT_packet(MQTT_packet.SUBACK, timestep, broker, port));
 					tops.add(newTopic);
 				}
 			}
-			else if(tops.size()==subbedTopics.size()){
+			else if(tops.size()==topics.size()){
 				//Forced Unsubscribe
 				newTopic = tops.get((int) Math.floor(Math.random()*tops.size()));
 				returnPackets.add(new MQTT_packet(MQTT_packet.UNSUBSCRIBE, timestep, port, broker, "topic:"+newTopic));
@@ -172,16 +178,6 @@ public class MQTT_protocol implements Protocol {
 					tops.remove(newTopic);
 				}
 			}
-			
-			if(pubSubs.contains(port)&&Math.random()<0.3){
-				//When also Pub, publish sometimes 
-				newTopic = topics.get((int) Math.floor(Math.random()*topics.size()));
-				returnPackets.add(new MQTT_packet(MQTT_packet.SUBSCRIBE, timestep, port, broker, "Topic:"+newTopic));
-				if(broker.getStatus()!=Port.CLOSED){
-					timestep+=broker.getResponseTime();
-					returnPackets.add(new MQTT_packet(MQTT_packet.SUBACK, timestep, broker, port));
-				}
-			}
 		}
 		if(pubs.contains(port)||pubSubs.contains(port)&&Math.random()<0.3){
 			String newTopic = topics.get((int) Math.floor(Math.random()*topics.size()));
@@ -201,7 +197,6 @@ public class MQTT_protocol implements Protocol {
 					if(!subbedTopics.get(p).contains(newTopic))continue;//Skip unsubbed ports
 					timestep+=broker.getResponseTime();
 					returnPackets.add(new MQTT_packet(MQTT_packet.PUBLISH, timestep, broker, p, msg));
-					
 					returnPackets.add(new MQTT_packet(MQTT_packet.PUBACK, timestep+p.getResponseTime(), p, broker));
 				}
 				for(Port p:pubSubs){