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/*
* Copyright 2016 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.traccar.BaseProtocolDecoder;
import org.traccar.DeviceSession;
import org.traccar.helper.UnitsConverter;
import org.traccar.model.Position;
import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import javax.xml.bind.DatatypeConverter;
import java.net.SocketAddress;
import java.nio.ByteOrder;
import java.nio.charset.StandardCharsets;
import java.util.Date;
public class At2000ProtocolDecoder extends BaseProtocolDecoder {
private static final int BLOCK_LENGTH = 16;
public At2000ProtocolDecoder(At2000Protocol protocol) {
super(protocol);
}
public static final int MSG_ACKNOWLEDGEMENT = 0x00;
public static final int MSG_DEVICE_ID = 0x01;
public static final int MSG_TRACK_REQUEST = 0x88;
public static final int MSG_TRACK_RESPONSE = 0x89;
public static final int MSG_SESSION_END = 0x0c;
private Cipher cipher;
private static void sendResponse(Channel channel) {
if (channel != null) {
ChannelBuffer response = ChannelBuffers.directBuffer(ByteOrder.LITTLE_ENDIAN, 2 * BLOCK_LENGTH);
response.writeByte(MSG_ACKNOWLEDGEMENT);
response.writeMedium(ChannelBuffers.swapMedium(1));
response.writeByte(0x00); // success
response.writerIndex(2 * BLOCK_LENGTH);
channel.write(response);
}
}
@Override
protected Object decode(
Channel channel, SocketAddress remoteAddress, Object msg) throws Exception {
ChannelBuffer buf = (ChannelBuffer) msg;
if (buf.getUnsignedByte(buf.readerIndex()) == 0x01) {
buf.readUnsignedByte(); // codec id
}
int type = buf.readUnsignedByte();
buf.readUnsignedMedium(); // length
buf.skipBytes(BLOCK_LENGTH - 1 - 3);
if (type == MSG_DEVICE_ID) {
String imei = buf.readBytes(15).toString(StandardCharsets.US_ASCII);
if (getDeviceSession(channel, remoteAddress, imei) != null) {
byte[] iv = new byte[BLOCK_LENGTH];
buf.readBytes(iv);
IvParameterSpec ivSpec = new IvParameterSpec(iv);
SecretKeySpec keySpec = new SecretKeySpec(
DatatypeConverter.parseHexBinary("000102030405060708090a0b0c0d0e0f"), "AES");
cipher = Cipher.getInstance("AES/CBC/NoPadding");
cipher.init(Cipher.DECRYPT_MODE, keySpec, ivSpec);
byte[] data = new byte[BLOCK_LENGTH];
buf.readBytes(data);
cipher.update(data);
}
} else if (type == MSG_TRACK_RESPONSE) {
DeviceSession deviceSession = getDeviceSession(channel, remoteAddress);
if (deviceSession == null) {
return null;
}
Position position = new Position();
position.setProtocol(getProtocolName());
position.setDeviceId(deviceSession.getDeviceId());
byte[] data = new byte[buf.capacity() - BLOCK_LENGTH];
buf.readBytes(data);
buf = ChannelBuffers.wrappedBuffer(ByteOrder.LITTLE_ENDIAN, cipher.update(data));
buf.readUnsignedShort(); // index
buf.readUnsignedShort(); // reserved
position.setValid(true);
position.setTime(new Date(buf.readLong() * 1000));
position.setLatitude(buf.readFloat());
position.setLongitude(buf.readFloat());
position.setAltitude(buf.readFloat());
position.setSpeed(UnitsConverter.knotsFromKph(buf.readFloat()));
position.setCourse(buf.readFloat());
return position;
}
sendResponse(channel);
return null;
}
}
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