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/*
* Copyright 2015 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 org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.ChannelBuffers;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.handler.codec.frame.LengthFieldBasedFrameDecoder;
import java.nio.ByteOrder;
public class TramigoFrameDecoder extends LengthFieldBasedFrameDecoder {
public TramigoFrameDecoder() {
super(1024, 6, 2, -8, 0);
}
@Override
protected Object decode(
ChannelHandlerContext ctx,
Channel channel,
ChannelBuffer buf) throws Exception {
if (buf.readableBytes() < 20) {
return null;
}
// Swap byte order for legacy protocol
if (buf.getUnsignedByte(buf.readerIndex()) == 0x80) {
int length = buf.readableBytes();
byte[] bytes = new byte[length];
buf.getBytes(buf.readerIndex(), bytes);
ChannelBuffer result = (ChannelBuffer) super.decode(
ctx, channel, ChannelBuffers.wrappedBuffer(ByteOrder.LITTLE_ENDIAN, bytes));
if (result != null) {
buf.skipBytes(result.readableBytes());
}
return result;
}
return super.decode(ctx, channel, buf);
}
}
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