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/*
* Copyright 2016 - 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;
import java.nio.charset.StandardCharsets;
public class L100FrameDecoder extends BaseFrameDecoder {
@Override
protected Object decode(
ChannelHandlerContext ctx, Channel channel, ByteBuf buf) throws Exception {
if (buf.readableBytes() < 10) {
return null;
}
if (buf.getCharSequence(buf.readerIndex(), 4, StandardCharsets.US_ASCII).toString().equals("ATL,")) {
return decodeNew(buf);
} else {
return decodeOld(buf);
}
}
private Object decodeOld(ByteBuf buf) {
int header = buf.getByte(buf.readerIndex());
boolean obd = header == 'L' || header == 'H';
int index;
if (obd) {
index = buf.indexOf(buf.readerIndex(), buf.writerIndex(), (byte) '*');
} else {
index = buf.indexOf(buf.readerIndex(), buf.writerIndex(), (byte) 0x02);
if (index < 0) {
index = buf.indexOf(buf.readerIndex(), buf.writerIndex(), (byte) 0x04);
if (index < 0) {
return null;
}
}
}
index += 2; // checksum
if (buf.writerIndex() >= index) {
if (!obd) {
buf.skipBytes(2); // header
}
ByteBuf frame = buf.readRetainedSlice(index - buf.readerIndex() - 2);
buf.skipBytes(2); // footer
return frame;
}
return null;
}
private Object decodeNew(ByteBuf buf) {
int index = buf.indexOf(buf.readerIndex(), buf.writerIndex(), (byte) '@');
if (index < 0) {
return null;
}
if (buf.writerIndex() >= index + 1) {
ByteBuf frame = buf.readRetainedSlice(index - buf.readerIndex());
buf.skipBytes(1); // delimiter
return frame;
}
return null;
}
}
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