Enhanced exception handling / logging for invalid messages

Signed-off-by: Maik Scheibler <[email protected]>

broker/src/main/java/io/moquette/broker/NettyUtils.java

@@ -16,8 +16,11 @@
 
 package io.moquette.broker;
 
+import java.io.IOException;
+
 import io.netty.channel.Channel;
 import io.netty.channel.ChannelHandlerContext;
+import io.netty.handler.codec.mqtt.MqttMessage;
 import io.netty.util.Attribute;
 import io.netty.util.AttributeKey;
 
@@ -69,6 +72,25 @@ public final class NettyUtils {
         return (String) channel.attr(NettyUtils.ATTR_KEY_USERNAME).get();
     }
 
-    private NettyUtils() {
+    /**
+	 * Validate that the provided message is an MqttMessage and that it does not contain a failed result.
+	 *
+	 * @param message to be validated
+	 * @return the casted provided message
+	 * @throws IOException in case of an fail message this will wrap the root cause
+	 * @throws ClassCastException if the provided message is no MqttMessage
+	 */
+	public static MqttMessage validateMessage(Object message) throws IOException, ClassCastException {
+		MqttMessage msg = (MqttMessage) message;
+		if (msg.decoderResult() != null && msg.decoderResult().isFailure()) {
+			throw new IOException("invalid massage", msg.decoderResult().cause());
+		}
+		if (msg.fixedHeader() == null) {
+			throw new IOException("Unknown packet, no fixedHeader present, no cause provided");
+		}
+		return msg;
+	}
+
+	private NettyUtils() {
     }
 }

broker/src/main/java/io/moquette/broker/NewNettyMQTTHandler.java

@@ -52,10 +52,7 @@ public class NewNettyMQTTHandler extends ChannelInboundHandlerAdapter {
 
     @Override
     public void channelRead(ChannelHandlerContext ctx, Object message) throws Exception {
-        MqttMessage msg = (MqttMessage) message;
-        if (msg.fixedHeader() == null) {
-            throw new IOException("Unknown packet");
-        }
+        MqttMessage msg = NettyUtils.validateMessage(message);
         final MQTTConnection mqttConnection = mqttConnection(ctx.channel());
         try {
             mqttConnection.handleMessage(msg);

broker/src/main/java/io/moquette/broker/metrics/MQTTMessageLogger.java

@@ -58,10 +58,7 @@ public class MQTTMessageLogger extends ChannelDuplexHandler {
         if (!(message instanceof MqttMessage)) {
             return;
         }
-        MqttMessage msg = (MqttMessage) message;
-        if (msg.fixedHeader() == null) {
-            throw new IOException("Unknown packet");
-        }
+        MqttMessage msg = NettyUtils.validateMessage(message);
         String clientID = NettyUtils.clientID(ctx.channel());
         MqttMessageType messageType = msg.fixedHeader().messageType();
         switch (messageType) {