Program: 155956
Project: 155956
Buggy source:
@Override protected Object decode(Channel channel,SocketAddress remoteAddress,Object msg) throws Exception {
  String sentence=(String)msg;
  if (sentence.startsWith("String_Node_Str") && channel != null) {
    channel.write(sentence + "String_Node_Str");
    return null;
  }
  Parser parser=new Parser(PATTERN,sentence);
  if (!parser.matches()) {
    return null;
  }
  DeviceSession deviceSession=getDeviceSession(channel,remoteAddress,parser.next());
  if (deviceSession == null) {
    return null;
  }
  Position position=new Position(getProtocolName());
  position.setDeviceId(deviceSession.getDeviceId());
  DateBuilder dateBuilder=new DateBuilder().setTime(parser.nextInt(0),parser.nextInt(0),parser.nextInt(0));
  String status=parser.next();
  position.setValid(status.toUpperCase().equals("String_Node_Str"));
  position.set(Position.KEY_STATUS,status);
  position.setLatitude(parser.nextCoordinate());
  position.setLongitude(parser.nextCoordinate());
  position.setSpeed(parser.nextDouble(0));
  position.setCourse(parser.nextDouble(0));
  dateBuilder.setDateReverse(parser.nextInt(0),parser.nextInt(0),parser.nextInt(0));
  position.setTime(dateBuilder.getDate());
  String eventCode=parser.next();
  String decodedAlarm=decodeAlarm(eventCode);
  if (decodedAlarm != null) {
    position.set(Position.KEY_ALARM,decodeAlarm(eventCode));
  }
  position.set(Position.KEY_EVENT,eventCode);
  double batteryVoltage=parser.nextDouble();
  if (parser.next().isEmpty()) {
    parser.next();
    batteryVoltage*=0.001;
  }
 else {
    batteryVoltage+=parser.nextDouble() * 0.001;
  }
  position.set(Position.KEY_BATTERY,batteryVoltage);
  position.set(Position.KEY_TOTAL_DISTANCE,parser.nextDouble());
  position.set(Position.KEY_GPS,parser.nextInt());
  position.set(Position.PREFIX_ADC + 1,parser.nextDouble() * 0.001);
  position.set(Position.PREFIX_ADC + 2,parser.nextDouble() * 0.001);
  String cellNetCodeString=parser.next();
  String cellIdString=parser.next();
  String countryCodeString=parser.next();
  String operatorCodeString=parser.next();
  if (cellNetCodeString != null && cellIdString != null && countryCodeString != null && operatorCodeString != null) {
    int cellNetCode=Integer.parseInt(cellNetCodeString,16);
    Long cellId=Long.parseLong(cellIdString,16);
    int countryCode=Integer.parseInt(countryCodeString);
    int operatorCode=Integer.parseInt(operatorCodeString);
    position.setNetwork(new Network(CellTower.from(countryCode,operatorCode,cellNetCode,cellId)));
  }
  String checksum=parser.next();
  String result=sentence.replaceAll("String_Node_Str","String_Node_Str");
  if (checksum == null || Integer.parseInt(checksum,16) != Checksum.xor(result)) {
    return null;
  }
  if (channel != null) {
    if (eventCode.equals("String_Node_Str")) {
      channel.write("String_Node_Str");
    }
 else     if (eventCode.equals("String_Node_Str") || eventCode.equals("String_Node_Str")) {
      channel.write("String_Node_Str");
    }
 else     if (eventCode.equals("String_Node_Str")) {
      channel.write("String_Node_Str");
    }
 else     if (Character.isLowerCase(status.charAt(0))) {
      String response="String_Node_Str" + eventCode + "String_Node_Str"+ checksum;
      response+=Checksum.nmea(response);
      response+="String_Node_Str";
      channel.write(response);
    }
  }
  return position;
}

Fixed version (ground truth):
@Override protected Object decode(Channel channel,SocketAddress remoteAddress,Object msg) throws Exception {
  String sentence=(String)msg;
  if (sentence.startsWith("String_Node_Str") && channel != null) {
    channel.write(sentence + "String_Node_Str");
    return null;
  }
  Parser parser=new Parser(PATTERN,sentence);
  if (!parser.matches()) {
    return null;
  }
  DeviceSession deviceSession=getDeviceSession(channel,remoteAddress,parser.next());
  if (deviceSession == null) {
    return null;
  }
  Position position=new Position(getProtocolName());
  position.setDeviceId(deviceSession.getDeviceId());
  DateBuilder dateBuilder=new DateBuilder().setTime(parser.nextInt(0),parser.nextInt(0),parser.nextInt(0));
  String status=parser.next();
  position.setValid(status.toUpperCase().equals("String_Node_Str"));
  position.set(Position.KEY_STATUS,status);
  position.setLatitude(parser.nextCoordinate());
  position.setLongitude(parser.nextCoordinate());
  position.setSpeed(parser.nextDouble(0));
  position.setCourse(parser.nextDouble(0));
  dateBuilder.setDateReverse(parser.nextInt(0),parser.nextInt(0),parser.nextInt(0));
  position.setTime(dateBuilder.getDate());
  String eventCode=parser.next();
  position.set(Position.KEY_ALARM,decodeAlarm(eventCode));
  position.set(Position.KEY_EVENT,eventCode);
  double batteryVoltage=parser.nextDouble();
  if (parser.next().isEmpty()) {
    parser.next();
    batteryVoltage*=0.001;
  }
 else {
    batteryVoltage+=parser.nextDouble() * 0.001;
  }
  position.set(Position.KEY_BATTERY,batteryVoltage);
  position.set(Position.KEY_ODOMETER,parser.nextDouble());
  position.set(Position.KEY_GPS,parser.nextInt());
  position.set(Position.PREFIX_ADC + 1,parser.nextDouble() * 0.001);
  position.set(Position.PREFIX_ADC + 2,parser.nextDouble() * 0.001);
  String lac=parser.next();
  String cid=parser.next();
  String mcc=parser.next();
  String mnc=parser.next();
  if (lac != null && cid != null && mcc != null && mnc != null) {
    position.setNetwork(new Network(CellTower.from(Integer.parseInt(mcc),Integer.parseInt(mnc),Integer.parseInt(lac,16),Long.parseLong(cid,16))));
  }
  String checksum=parser.next();
  if (channel != null) {
    if (eventCode.equals("String_Node_Str")) {
      channel.write("String_Node_Str");
    }
 else     if (eventCode.equals("String_Node_Str") || eventCode.equals("String_Node_Str")) {
      channel.write("String_Node_Str");
    }
 else     if (eventCode.equals("String_Node_Str")) {
      channel.write("String_Node_Str");
    }
 else     if (Character.isLowerCase(status.charAt(0))) {
      String response="String_Node_Str" + eventCode + "String_Node_Str"+ checksum;
      response+=Checksum.nmea(response);
      response+="String_Node_Str";
      channel.write(response);
    }
  }
  return position;
}