/**
* 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.IOException;
import org.apache.activemq.transport.tcp.TcpTransport;
import org.fusesource.hawtbuf.Buffer;
import org.fusesource.hawtbuf.DataByteArrayInputStream;
import org.fusesource.mqtt.codec.MQTTFrame;
public class MQTTCodec {
private final MQTTFrameSink frameSink;
private final MQTTWireFormat wireFormat;
private byte header;
private int contentLength = -1;
private FrameParser currentParser;
private final Buffer scratch = new Buffer(8 * 1024);
private Buffer currentBuffer;
/**
* Sink for newly decoded MQTT Frames.
*/
public interface MQTTFrameSink {
void onFrame(MQTTFrame mqttFrame);
}
public MQTTCodec(MQTTFrameSink sink) {
this(sink, null);
}
public MQTTCodec(MQTTFrameSink sink, MQTTWireFormat wireFormat) {
this.frameSink = sink;
this.wireFormat = wireFormat;
}
public MQTTCodec(final TcpTransport transport) {
this(transport, null);
}
public MQTTCodec(final TcpTransport transport, MQTTWireFormat wireFormat) {
this.wireFormat = wireFormat;
this.frameSink = new MQTTFrameSink() {
@Override
public void onFrame(MQTTFrame mqttFrame) {
transport.doConsume(mqttFrame);
}
};
}
public void parse(DataByteArrayInputStream input, int readSize) throws Exception {
if (currentParser == null) {
currentParser = initializeHeaderParser();
}
// Parser stack will run until current incoming data has all been consumed.
currentParser.parse(input, readSize);
}
private void processCommand() throws IOException {
Buffer frameContents = null;
if (currentBuffer == scratch) {
frameContents = scratch.deepCopy();
} else {
frameContents = currentBuffer;
currentBuffer = null;
}
MQTTFrame frame = new MQTTFrame(frameContents).header(header);
frameSink.onFrame(frame);
}
private int getMaxFrameSize() {
return wireFormat != null ? wireFormat.getMaxFrameSize() : MQTTWireFormat.MAX_MESSAGE_LENGTH;
}
//----- Prepare the current frame parser for use -------------------------//
private FrameParser initializeHeaderParser() throws IOException {
headerParser.reset();
return headerParser;
}
private FrameParser initializeVariableLengthParser() throws IOException {
variableLengthParser.reset();
return variableLengthParser;
}
private FrameParser initializeContentParser() throws IOException {
contentParser.reset();
return contentParser;
}
//----- Frame parser implementations -------------------------------------//
private interface FrameParser {
void parse(DataByteArrayInputStream data, int readSize) throws IOException;
void reset() throws IOException;
}
private final FrameParser headerParser = new FrameParser() {
@Override
public void parse(DataByteArrayInputStream data, int readSize) throws IOException {
while (readSize-- > 0) {
byte b = data.readByte();
// skip repeating nulls
if (b == 0) {
continue;
}
header = b;
currentParser = initializeVariableLengthParser();
if (readSize > 0) {
currentParser.parse(data, readSize);
}
return;
}
}
@Override
public void reset() throws IOException {
header = -1;
contentLength = -1;
}
};
private final FrameParser variableLengthParser = new FrameParser() {
private byte digit;
private int multiplier = 1;
private int length;
@Override
public void parse(DataByteArrayInputStream data, int readSize) throws IOException {
int i = 0;
while (i++ < readSize) {
digit = data.readByte();
length += (digit & 0x7F) * multiplier;
multiplier <<= 7;
if ((digit & 0x80) == 0) {
if (length == 0) {
processCommand();
currentParser = initializeHeaderParser();
} else {
if (length > getMaxFrameSize()) {
throw new IOException("The maximum message length was exceeded");
}
currentParser = initializeContentParser();
contentLength = length;
}
readSize = readSize - i;
if (readSize > 0) {
currentParser.parse(data, readSize);
}
return;
}
}
}
@Override
public void reset() throws IOException {
digit = 0;
multiplier = 1;
length = 0;
}
};
private final FrameParser contentParser = new FrameParser() {
private int payLoadRead = 0;
@Override
public void parse(DataByteArrayInputStream data, int readSize) throws IOException {
if (currentBuffer == null) {
if (contentLength < scratch.length()) {
currentBuffer = scratch;
currentBuffer.length = contentLength;
} else {
currentBuffer = new Buffer(contentLength);
}
}
int length = Math.min(readSize, contentLength - payLoadRead);
payLoadRead += data.read(currentBuffer.data, payLoadRead, length);
if (payLoadRead == contentLength) {
processCommand();
currentParser = initializeHeaderParser();
readSize = readSize - length;
if (readSize > 0) {
currentParser.parse(data, readSize);
}
}
}
@Override
public void reset() throws IOException {
contentLength = -1;
payLoadRead = 0;
scratch.reset();
currentBuffer = null;
}
};
}