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/*
* Copyright 2017 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.FrameDecoder;
import java.nio.charset.StandardCharsets;
public class WatchFrameDecoder extends FrameDecoder {
public static final int MESSAGE_HEADER = 20;
@Override
protected Object decode(
ChannelHandlerContext ctx, Channel channel, ChannelBuffer buf) throws Exception {
if (buf.readableBytes() >= MESSAGE_HEADER) {
ChannelBuffer lengthBuffer = ChannelBuffers.dynamicBuffer();
buf.getBytes(buf.readerIndex() + MESSAGE_HEADER - 4 - 1, lengthBuffer, 4);
int length = Integer.parseInt(lengthBuffer.toString(StandardCharsets.US_ASCII), 16) + MESSAGE_HEADER + 1;
if (buf.readableBytes() >= length) {
ChannelBuffer frame = ChannelBuffers.dynamicBuffer();
int endIndex = buf.readerIndex() + length;
while (buf.readerIndex() < endIndex) {
byte b = buf.readByte();
if (b == 0x7D) {
switch (buf.readByte()) {
case 0x01:
frame.writeByte(0x7D);
break;
case 0x02:
frame.writeByte(0x5B);
break;
case 0x03:
frame.writeByte(0x5D);
break;
case 0x04:
frame.writeByte(0x2C);
break;
case 0x05:
frame.writeByte(0x2A);
break;
default:
throw new IllegalArgumentException();
}
} else {
frame.writeByte(b);
}
}
return frame;
}
}
return null;
}
}
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