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/*
* Copyright 2021 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.buffer.Unpooled;
import io.netty.channel.Channel;
import io.netty.channel.ChannelHandlerContext;
import org.traccar.BaseFrameDecoder;
import org.traccar.helper.BufferUtil;
public class Xexun2FrameDecoder extends BaseFrameDecoder {
@Override
protected Object decode(
ChannelHandlerContext ctx, Channel channel, ByteBuf buf) throws Exception {
if (buf.readableBytes() < 5) {
return null;
}
ByteBuf flag = Unpooled.wrappedBuffer(new byte[] {(byte) 0xfa, (byte) 0xaf});
int index;
try {
index = BufferUtil.indexOf(flag, buf, buf.readerIndex() + 2, buf.writerIndex());
} finally {
flag.release();
}
if (index >= 0) {
ByteBuf result = Unpooled.buffer(index + 2 - buf.readerIndex());
while (buf.readerIndex() < index + 2) {
int b = buf.readUnsignedByte();
if (b == 0xfb && buf.isReadable() && buf.getUnsignedByte(buf.readerIndex()) == 0xbf) {
buf.readUnsignedByte(); // skip
int ext = buf.readUnsignedByte();
if (ext == 0x01) {
result.writeByte(0xfa);
result.writeByte(0xaf);
} else if (ext == 0x02) {
result.writeByte(0xfb);
result.writeByte(0xbf);
}
} else {
result.writeByte(b);
}
}
return result;
}
return null;
}
}
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