content: /**
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You under the Apache License, Version 2.0
   * (the "License"); you may not use this file except in compliance with
   * the License.  You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.activemq.transport.protocol;
  
  import java.nio.ByteBuffer;
  
  /**
   *
   *
   */
  public class MqttProtocolVerifier implements ProtocolVerifier {
  
      @Override
      public boolean isProtocol(byte[] value) {
         ByteBuffer buf = ByteBuffer.wrap(value);
  
         if (!(buf.get() == 16 && validateRemainingLength(buf) && buf.get() == (byte) 0)) {
             return false;
         }
         byte b = buf.get() ;
         return ((b == 4 || b == 6) && (buf.get() == 77));
      }
  
      private boolean validateRemainingLength(ByteBuffer buffer) {
         byte msb = (byte) 0b10000000;
         for (byte i = 0; i < 4; i++) {
            if ((buffer.get() & msb) != msb) {
               return true;
            }
         }
         return false;
      }
  }
  