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/*
* Copyright 2013 - 2018 Anton Tananaev (anton@traccar.org)
*
* Licensed 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.traccar.protocol;
import io.netty.buffer.ByteBuf;
import io.netty.channel.Channel;
import io.netty.channel.ChannelHandlerContext;
import org.traccar.BaseFrameDecoder;
public class H02FrameDecoder extends BaseFrameDecoder {
private static final int MESSAGE_SHORT = 32;
private static final int MESSAGE_LONG = 45;
private int messageLength;
public H02FrameDecoder(int messageLength) {
this.messageLength = messageLength;
}
@Override
protected Object decode(
ChannelHandlerContext ctx, Channel channel, ByteBuf buf) throws Exception {
char marker = (char) buf.getByte(buf.readerIndex());
while (marker != '*' && marker != '$' && marker != 'X' && buf.readableBytes() > 0) {
buf.skipBytes(1);
if (buf.readableBytes() > 0) {
marker = (char) buf.getByte(buf.readerIndex());
}
}
switch (marker) {
case '*':
// Return text message
int index = buf.indexOf(buf.readerIndex(), buf.writerIndex(), (byte) '#');
if (index != -1) {
ByteBuf result = buf.readRetainedSlice(index + 1 - buf.readerIndex());
while (buf.isReadable()
&& (buf.getByte(buf.readerIndex()) == '\r' || buf.getByte(buf.readerIndex()) == '\n')) {
buf.readByte(); // skip new line
}
return result;
}
break;
case '$':
if (messageLength == 0) {
if (buf.readableBytes() == MESSAGE_LONG) {
messageLength = MESSAGE_LONG;
} else {
messageLength = MESSAGE_SHORT;
}
}
if (buf.readableBytes() >= messageLength) {
return buf.readRetainedSlice(messageLength);
}
break;
case 'X':
if (buf.readableBytes() >= MESSAGE_SHORT) {
return buf.readRetainedSlice(MESSAGE_SHORT);
}
break;
default:
return null;
}
return null;
}
}
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