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/*
* Copyright 2017 Valerii Vyshniak (val@val.one)
* 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.channel.Channel;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.handler.codec.frame.FrameDecoder;
public class Tk103FrameDecoder extends FrameDecoder {
private static final int FRAME_MIN_SIZE = 2;
private static final int FRAME_MAX_SIZE = 1024;
private static final byte FRAME_START_SYMBOL = (byte) '(';
private static final byte FRAME_END_SYMBOL = (byte) ')';
private static final byte FRAME_FREE_TEXT_BLOCK_SYMBOL = (byte) '$';
@Override
protected Object decode(
ChannelHandlerContext ctx,
Channel channel,
ChannelBuffer buf) throws Exception {
if (buf.readableBytes() < FRAME_MIN_SIZE) {
return null;
}
int indexStart = buf.indexOf(buf.readerIndex(), buf.writerIndex(), FRAME_START_SYMBOL);
if (indexStart == -1) {
buf.clear();
return null;
}
indexStart++;
int index, cnt;
for (index = indexStart, cnt = 0;; index++) {
int i = index;
index = buf.indexOf(index, buf.writerIndex(), FRAME_END_SYMBOL);
if (index == -1) {
break;
}
for (;; i++, cnt++) {
i = buf.indexOf(i, index, FRAME_FREE_TEXT_BLOCK_SYMBOL);
if (i == -1 || i >= index) {
break;
}
}
if (cnt % 2 == 0) {
break;
}
}
if (index == -1) {
while (buf.readableBytes() > FRAME_MAX_SIZE) {
int i = buf.indexOf(buf.readerIndex() + 1, buf.writerIndex(), FRAME_START_SYMBOL);
if (i == -1) {
buf.clear();
} else {
buf.readerIndex(i);
}
}
return null;
}
buf.readerIndex(indexStart);
ChannelBuffer result = buf.readBytes(index - indexStart);
buf.readerIndex(buf.readerIndex() + 1);
return result;
}
}
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