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/*
* Copyright 2017 Ivan Muratov (binakot@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.channel.Channel;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.handler.codec.frame.FrameDecoder;
public class Arnavi4FrameDecoder extends FrameDecoder {
private static final int PACKET_MINIMUM_LENGTH = 4;
private static final int RECORD_MINIMUM_LENGTH = 8;
static final byte HEADER_START_SIGN = (byte) 0xff;
static final byte HEADER_VERSION_1 = 0x22;
static final byte HEADER_VERSION_2 = 0x23;
private static final int HEADER_LENGTH = 10;
private static final byte PACKAGE_START_SIGN = 0x5b;
private static final byte PACKAGE_END_SIGN = 0x5d;
private static final int PACKAGE_MIN_PARCEL_NUMBER = 0x01;
private static final int PACKAGE_MAX_PARCEL_NUMBER = 0xfb;
@Override
protected Object decode(
ChannelHandlerContext ctx,
Channel channel,
ChannelBuffer buf) throws Exception {
if (buf.readableBytes() < PACKET_MINIMUM_LENGTH) {
return null;
}
if (buf.getByte(0) == HEADER_START_SIGN
&& buf.readableBytes() == HEADER_LENGTH
&& (buf.getByte(1) == HEADER_VERSION_1 || buf.getByte(1) == HEADER_VERSION_2)) {
return buf.readBytes(HEADER_LENGTH);
}
int index = buf.getUnsignedByte(1); // parcel number
if (buf.getByte(0) == PACKAGE_START_SIGN
&& index >= PACKAGE_MIN_PARCEL_NUMBER && index <= PACKAGE_MAX_PARCEL_NUMBER) {
int bufferPosition = 2; // start sign + parcel number
while (bufferPosition + RECORD_MINIMUM_LENGTH < buf.readableBytes()
&& buf.getByte(bufferPosition) != PACKAGE_END_SIGN) {
int dataLength = buf.getUnsignedShort(bufferPosition + 1);
bufferPosition += RECORD_MINIMUM_LENGTH + dataLength; // type + data length + unixtime + data + crc
}
if (bufferPosition < buf.readableBytes()
&& buf.getByte(bufferPosition) == PACKAGE_END_SIGN) {
return buf.readBytes(bufferPosition + 1); // end sign
}
}
return null;
}
}
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