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/*
* Copyright 2013 Anton Tananaev (anton.tananaev@gmail.com)
*
* 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.DelimiterBasedFrameDecoder;
public class IntellitracFrameDecoder extends DelimiterBasedFrameDecoder {
private static final int MESSAGE_MINIMUM_LENGTH = 0;
private static final byte[] delimiter = {(byte) '\r', (byte) '\n'};
public IntellitracFrameDecoder(int maxFrameLength) {
super(maxFrameLength, ChannelBuffers.wrappedBuffer(delimiter));
}
// example of sync header: 0xFA 0xF8 0x1B 0x01 0x81 0x60 0x33 0x3C
@Override
protected Object decode(ChannelHandlerContext ctx, Channel channel, ChannelBuffer buf) throws Exception {
// Check minimum length
if (buf.readableBytes() < MESSAGE_MINIMUM_LENGTH) {
return null;
}
// Check for sync packet
if (buf.getUnsignedShort(buf.readerIndex()) == 0xFAF8) {
ChannelBuffer syncMessage = buf.readBytes(8);
if (channel != null) {
channel.write(syncMessage);
}
}
return super.decode(ctx, channel, buf);
}
}
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