/**
* 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.mqtt;
import java.io.UnsupportedEncodingException;
import org.fusesource.mqtt.codec.CONNECT;
import org.fusesource.mqtt.codec.DISCONNECT;
import org.fusesource.mqtt.codec.PINGREQ;
import org.fusesource.mqtt.codec.PUBACK;
import org.fusesource.mqtt.codec.PUBCOMP;
import org.fusesource.mqtt.codec.PUBLISH;
import org.fusesource.mqtt.codec.PUBREC;
import org.fusesource.mqtt.codec.PUBREL;
import org.fusesource.mqtt.codec.SUBSCRIBE;
import org.fusesource.mqtt.codec.UNSUBSCRIBE;
/**
* A set of static methods useful for handling MQTT based client connections.
*/
public class MQTTProtocolSupport {
private static final int TOPIC_NAME_MIN_LENGTH = 1;
private static final int TOPIC_NAME_MAX_LENGTH = 65535;
private static final String MULTI_LEVEL_WILDCARD = "#";
private static final String SINGLE_LEVEL_WILDCARD = "+";
private static final char MULTI_LEVEL_WILDCARD_CHAR = '#';
private static final char SINGLE_LEVEL_WILDCARD_CHAR = '+';
private static final char TOPIC_LEVEL_SEPERATOR_CHAR = '/';
/**
* Converts an MQTT formatted Topic name into a suitable ActiveMQ Destination
* name string.
*
* @param name
* the MQTT formatted topic name.
*
* @return an destination name that fits the ActiveMQ conventions.
*/
public static String convertMQTTToActiveMQ(String name) {
char[] chars = name.toCharArray();
for (int i = 0; i < chars.length; i++) {
switch(chars[i]) {
case '#':
chars[i] = '>';
break;
case '>':
chars[i] = '#';
break;
case '+':
chars[i] = '*';
break;
case '*':
chars[i] = '+';
break;
case '/':
chars[i] = '.';
break;
case '.':
chars[i] = '/';
break;
}
}
String rc = new String(chars);
return rc;
}
/**
* Converts an ActiveMQ destination name into a correctly formatted
* MQTT destination name.
*
* @param destinationName
* the ActiveMQ destination name to process.
*
* @return a destination name formatted for MQTT.
*/
public static String convertActiveMQToMQTT(String destinationName) {
char[] chars = destinationName.toCharArray();
for (int i = 0; i < chars.length; i++) {
switch(chars[i]) {
case '>':
chars[i] = '#';
break;
case '#':
chars[i] = '>';
break;
case '*':
chars[i] = '+';
break;
case '+':
chars[i] = '*';
break;
case '.':
chars[i] = '/';
break;
case '/':
chars[i] = '.';
break;
}
}
String rc = new String(chars);
return rc;
}
/**
* Given an MQTT header byte, determine the command type that the header
* represents.
*
* @param header
* the byte value for the MQTT frame header.
*
* @return a string value for the given command type.
*/
public static String commandType(byte header) {
byte messageType = (byte) ((header & 0xF0) >>> 4);
switch (messageType) {
case PINGREQ.TYPE:
return "PINGREQ";
case CONNECT.TYPE:
return "CONNECT";
case DISCONNECT.TYPE:
return "DISCONNECT";
case SUBSCRIBE.TYPE:
return "SUBSCRIBE";
case UNSUBSCRIBE.TYPE:
return "UNSUBSCRIBE";
case PUBLISH.TYPE:
return "PUBLISH";
case PUBACK.TYPE:
return "PUBACK";
case PUBREC.TYPE:
return "PUBREC";
case PUBREL.TYPE:
return "PUBREL";
case PUBCOMP.TYPE:
return "PUBCOMP";
default:
return "UNKNOWN";
}
}
/**
* Validate that the Topic names given by client commands are valid
* based on the MQTT protocol specification.
*
* @param topicName
* the given Topic name provided by the client.
*
* @throws MQTTProtocolException if the value given is invalid.
*/
public static void validate(String topicName) throws MQTTProtocolException {
int topicLen = 0;
try {
topicLen = topicName.getBytes("UTF-8").length;
} catch (UnsupportedEncodingException e) {
throw new MQTTProtocolException("Topic name contained invalid UTF-8 encoding.");
}
// Spec: Unless stated otherwise all UTF-8 encoded strings can have any length in
// the range 0 to 65535 bytes.
if (topicLen < TOPIC_NAME_MIN_LENGTH || topicLen > TOPIC_NAME_MAX_LENGTH) {
throw new MQTTProtocolException("Topic name given had invliad length.");
}
// 4.7.1.2 and 4.7.1.3 these can stand alone
if (MULTI_LEVEL_WILDCARD.equals(topicName) || SINGLE_LEVEL_WILDCARD.equals(topicName)) {
return;
}
// Spec: 4.7.1.2
// The multi-level wildcard character MUST be specified either on its own or following a
// topic level separator. In either case it MUST be the last character specified in the
// Topic Filter [MQTT-4.7.1-2].
int numWildCards = 0;
for (int i = 0; i < topicName.length(); ++i) {
if (topicName.charAt(i) == MULTI_LEVEL_WILDCARD_CHAR) {
numWildCards++;
// If prev exists it must be a separator
if (i > 0 && topicName.charAt(i - 1) != TOPIC_LEVEL_SEPERATOR_CHAR) {
throw new MQTTProtocolException("The multi level wildcard must stand alone: " + topicName);
}
}
if (numWildCards > 1) {
throw new MQTTProtocolException("Topic Filter can only have one multi-level filter: " + topicName);
}
}
if (topicName.contains(MULTI_LEVEL_WILDCARD) && !topicName.endsWith(MULTI_LEVEL_WILDCARD)) {
throw new MQTTProtocolException("The multi-level filter must be at the end of the Topic name: " + topicName);
}
// Spec: 4.7.1.3
// The single-level wildcard can be used at any level in the Topic Filter, including
// first and last levels. Where it is used it MUST occupy an entire level of the filter
//
// [MQTT-4.7.1-3]. It can be used at more than one level in the Topic Filter and can be
// used in conjunction with the multilevel wildcard.
for (int i = 0; i < topicName.length(); ++i) {
if (topicName.charAt(i) != SINGLE_LEVEL_WILDCARD_CHAR) {
continue;
}
// If prev exists it must be a separator
if (i > 0 && topicName.charAt(i - 1) != TOPIC_LEVEL_SEPERATOR_CHAR) {
throw new MQTTProtocolException("The single level wildcard must stand alone: " + topicName);
}
// If next exists it must be a separator
if (i < topicName.length() - 1 && topicName.charAt(i + 1) != TOPIC_LEVEL_SEPERATOR_CHAR) {
throw new MQTTProtocolException("The single level wildcard must stand alone: " + topicName);
}
}
}
}