001/** 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.activemq.transport.protocol; 018 019import java.nio.ByteBuffer; 020 021/** 022 * 023 * 024 */ 025public class MqttProtocolVerifier implements ProtocolVerifier { 026 027 @Override 028 public boolean isProtocol(byte[] value) { 029 ByteBuffer buf = ByteBuffer.wrap(value); 030 031 if (!(buf.get() == 16 && validateRemainingLength(buf) && buf.get() == (byte) 0)) { 032 return false; 033 } 034 byte b = buf.get() ; 035 return ((b == 4 || b == 6) && (buf.get() == 77)); 036 } 037 038 private boolean validateRemainingLength(ByteBuffer buffer) { 039 byte msb = (byte) 0b10000000; 040 for (byte i = 0; i < 4; i++) { 041 if ((buffer.get() & msb) != msb) { 042 return true; 043 } 044 } 045 return false; 046 } 047}