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   1 /**
   2  * Copyright (c) 2010-2021 Contributors to the openHAB project
   3  *
   4  * See the NOTICE file(s) distributed with this work for additional
   5  * information.
   6  *
   7  * This program and the accompanying materials are made available under the
   8  * terms of the Eclipse Public License 2.0 which is available at
   9  * http://www.eclipse.org/legal/epl-2.0
  10  *
  11  * SPDX-License-Identifier: EPL-2.0
  12  */
  13 package org.openhab.binding.powermax.internal.connector;
  14
  15 import java.io.IOException;
  16 import java.io.InterruptedIOException;
  17 import java.util.Arrays;
  18
  19 import org.openhab.binding.powermax.internal.message.PowermaxCommManager;
  20 import org.openhab.binding.powermax.internal.message.PowermaxReceiveType;
  21 import org.openhab.core.util.HexUtils;
  22 import org.slf4j.Logger;
  23 import org.slf4j.LoggerFactory;
  24
  25 /**
  26  * A class that reads messages from the Visonic alarm panel in a dedicated thread
  27  *
  28  * @author Laurent Garnier - Initial contribution
  29  */
  30 public class PowermaxReaderThread extends Thread {
  31
  32     private final Logger logger = LoggerFactory.getLogger(PowermaxReaderThread.class);
  33
  34     private static final int READ_BUFFER_SIZE = 20;
  35     private static final int MAX_MSG_SIZE = 0xC0;
  36
  37     private PowermaxConnector connector;
  38
  39     /**
  40      * Constructor
  41      *
  42      * @param in the input stream
  43      * @param connector the object that should handle the received message
  44      * @param threadName the name of the thread
  45      */
  46     public PowermaxReaderThread(PowermaxConnector connector, String threadName) {
  47         super(threadName);
  48         this.connector = connector;
  49     }
  50
  51     @Override
  52     public void run() {
  53         logger.debug("Data listener started");
  54
  55         byte[] readDataBuffer = new byte[READ_BUFFER_SIZE];
  56         byte[] dataBuffer = new byte[MAX_MSG_SIZE];
  57         int index = 0;
  58         int msgLen = 0;
  59         boolean variableLen = false;
  60
  61         try {
  62             while (!Thread.interrupted()) {
  63                 int len = connector.read(readDataBuffer);
  64                 if (len > 0) {
  65                     for (int i = 0; i < len; i++) {
  66                         if (index >= MAX_MSG_SIZE) {
  67                             // too many bytes received, try to find new start
  68                             if (logger.isDebugEnabled()) {
  69                                 byte[] logData = Arrays.copyOf(dataBuffer, index);
  70                                 logger.debug("Truncating message {}", HexUtils.bytesToHex(logData));
  71                             }
  72                             index = 0;
  73                         }
  74
  75                         if (index == 0 && readDataBuffer[i] == 0x0D) {
  76                             // Preamble
  77
  78                             dataBuffer[index++] = readDataBuffer[i];
  79                         } else if (index > 0) {
  80                             dataBuffer[index++] = readDataBuffer[i];
  81
  82                             if (index == 2) {
  83                                 try {
  84                                     PowermaxReceiveType msgType = PowermaxReceiveType.fromCode(readDataBuffer[i]);
  85                                     msgLen = msgType.getLength();
  86                                     variableLen = ((readDataBuffer[i] & 0x000000FF) > 0x10) && (msgLen == 0);
  87                                 } catch (IllegalArgumentException arg0) {
  88                                     msgLen = 0;
  89                                     variableLen = false;
  90                                 }
  91                             } else if (index == 5 && variableLen) {
  92                                 msgLen = (readDataBuffer[i] & 0x000000FF) + 7;
  93                             } else if ((msgLen == 0 && readDataBuffer[i] == 0x0A) || (index == msgLen)) {
  94                                 // Postamble
  95
  96                                 if (readDataBuffer[i] != 0x0A && dataBuffer[index - 1] == 0x43) {
  97                                     // adjust message length for 0x43
  98                                     msgLen++;
  99                                 } else if (checkCRC(dataBuffer, index)) {
 100                                     // whole message received with a right CRC
 101
 102                                     byte[] msg = new byte[index];
 103                                     msg = Arrays.copyOf(dataBuffer, index);
 104
 105                                     connector.setWaitingForResponse(System.currentTimeMillis());
 106                                     connector.handleIncomingMessage(msg);
 107
 108                                     // find new preamble
 109                                     index = 0;
 110                                 } else if (msgLen == 0) {
 111                                     // CRC check failed for a message with an unknown length
 112                                     logger.debug("Message length is now {} but message is apparently not complete",
 113                                             index + 1);
 114                                 } else {
 115                                     // CRC check failed for a message with a known length
 116
 117                                     connector.setWaitingForResponse(System.currentTimeMillis());
 118
 119                                     // find new preamble
 120                                     index = 0;
 121                                 }
 122                             }
 123                         }
 124                     }
 125                 }
 126             }
 127         } catch (InterruptedIOException e) {
 128             Thread.currentThread().interrupt();
 129             logger.debug("Interrupted via InterruptedIOException");
 130         } catch (IOException e) {
 131             logger.debug("Reading failed: {}", e.getMessage(), e);
 132         }
 133
 134         logger.debug("Data listener stopped");
 135     }
 136
 137     /**
 138      * Check if the CRC inside a received message is valid or not
 139      *
 140      * @param data the buffer containing the message
 141      * @param len the size of the message in the buffer
 142      *
 143      * @return true if the CRC is valid or false if not
 144      */
 145     private boolean checkCRC(byte[] data, int len) {
 146         byte checksum = PowermaxCommManager.computeCRC(data, len);
 147         byte expected = data[len - 2];
 148         if (checksum != expected) {
 149             byte[] logData = Arrays.copyOf(data, len);
 150             logger.warn("Powermax alarm binding: message CRC check failed (expected {}, got {}, message {})",
 151                     String.format("%02X", expected), String.format("%02X", checksum), HexUtils.bytesToHex(logData));
 152         }
 153         return (checksum == expected);
 154     }
 155 }