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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 {
static final int PACKET_MIN_LENGTH = 4;
static final byte HEADER_START_SIGN = (byte) 0xFF;
static final byte HEADER_VERSION_1 = 0x22;
static final byte HEADER_VERSION_2 = 0x23;
static final int HEADER_LENGTH = 10;
static final byte PACKAGE_START_SIGN = 0x5B;
static final byte PACKAGE_END_SIGN = 0x5D;
static final int PACKAGE_MIN_PARCEL_NUMBER = 0x01;
static final int PACKAGE_MAX_PARCEL_NUMBER = 0xFB;
@Override
protected Object decode(
ChannelHandlerContext ctx,
Channel channel,
ChannelBuffer buf) throws Exception {
if (buf.readableBytes() < PACKET_MIN_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.getByte(1) & 0xFF; // parcel number
if (buf.getByte(0) == PACKAGE_START_SIGN
&& index >= PACKAGE_MIN_PARCEL_NUMBER && index <= PACKAGE_MAX_PARCEL_NUMBER) {
// package: 1 byte start sign, 1 byte parcel number, packets, 1 byte end sign
int packetStartIndex = 2;
while (packetStartIndex + 8 < buf.readableBytes() && buf.getByte(packetStartIndex) != PACKAGE_END_SIGN) {
// packet: 1 byte type, 2 bytes length, 4 bytes unixtime, length-bytes data, 1 byte crc
packetStartIndex += buf.getUnsignedShort(packetStartIndex + 1) + 8;
}
return buf.readBytes(packetStartIndex + 1);
}
return null;
}
}
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