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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.amazondashbutton.internal.discovery;
  14
  15 import static org.openhab.binding.amazondashbutton.internal.AmazonDashButtonBindingConstants.*;
  16
  17 import java.math.BigDecimal;
  18 import java.util.Collections;
  19 import java.util.Map;
  20 import java.util.Set;
  21 import java.util.concurrent.ConcurrentHashMap;
  22 import java.util.stream.Collectors;
  23 import java.util.stream.Stream;
  24
  25 import org.openhab.binding.amazondashbutton.internal.capturing.PacketCapturingHandler;
  26 import org.openhab.binding.amazondashbutton.internal.capturing.PacketCapturingService;
  27 import org.openhab.binding.amazondashbutton.internal.pcap.PcapNetworkInterfaceListener;
  28 import org.openhab.binding.amazondashbutton.internal.pcap.PcapNetworkInterfaceService;
  29 import org.openhab.binding.amazondashbutton.internal.pcap.PcapNetworkInterfaceWrapper;
  30 import org.openhab.core.config.discovery.AbstractDiscoveryService;
  31 import org.openhab.core.config.discovery.DiscoveryResult;
  32 import org.openhab.core.config.discovery.DiscoveryResultBuilder;
  33 import org.openhab.core.config.discovery.DiscoveryService;
  34 import org.openhab.core.thing.ThingUID;
  35 import org.osgi.service.component.annotations.Component;
  36 import org.pcap4j.core.PcapNetworkInterface;
  37 import org.pcap4j.util.MacAddress;
  38 import org.slf4j.Logger;
  39 import org.slf4j.LoggerFactory;
  40
  41 /**
  42  * The {@link AmazonDashButtonDiscoveryService} is responsible for discovering Amazon Dash Buttons. It does so by
  43  * capturing ARP and BOOTP requests from all available network devices.
  44  *
  45  * While scanning the user has to press the button in order to send an ARP and BOOTP request packet. The
  46  * {@link AmazonDashButtonDiscoveryService} captures this packet and checks the device's MAC address which sent the
  47  * request against a static list of vendor prefixes ({@link #VENDOR_PREFIXES}).
  48  *
  49  * If an Amazon MAC address is detected a {@link DiscoveryResult} is built and passed to
  50  * {@link #thingDiscovered(DiscoveryResult)}.
  51  *
  52  * @author Oliver Libutzki - Initial contribution
  53  *
  54  */
  55 @Component(service = DiscoveryService.class, configurationPid = "discovery.amazondashbutton")
  56 public class AmazonDashButtonDiscoveryService extends AbstractDiscoveryService implements PcapNetworkInterfaceListener {
  57
  58     private static final int DISCOVER_TIMEOUT_SECONDS = 30;
  59
  60     private final Logger logger = LoggerFactory.getLogger(AmazonDashButtonDiscoveryService.class);
  61
  62     /**
  63      * The Amazon Dash button vendor prefixes
  64      */
  65     // @formatter:off
  66     private static final Set<String> VENDOR_PREFIXES = Collections.unmodifiableSet(Stream.of(
  67             "F0:D2:F1",
  68             "88:71:E5",
  69             "FC:A1:83",
  70             "F0:27:2D",
  71             "74:C2:46",
  72             "68:37:E9",
  73             "78:E1:03",
  74             "38:F7:3D",
  75             "50:DC:E7",
  76             "A0:02:DC",
  77             "0C:47:C9",
  78             "74:75:48",
  79             "AC:63:BE",
  80             "FC:A6:67",
  81             "18:74:2E",
  82             "00:FC:8B",
  83             "FC:65:DE",
  84             "6C:56:97",
  85             "44:65:0D",
  86             "50:F5:DA",
  87             "68:54:FD",
  88             "40:B4:CD",
  89             "84:D6:D0",
  90             "34:D2:70",
  91             "B4:7C:9C"
  92         ).collect(Collectors.toSet()));
  93     // @formatter:on
  94
  95     /**
  96      * Returns true if the passed macAddress is an Amazon MAC address.
  97      *
  98      * @param macAddress
  99      * @return
 100      */
 101     private static boolean isAmazonVendor(String macAddress) {
 102         String vendorPrefix = macAddress.substring(0, 8).toUpperCase();
 103         return VENDOR_PREFIXES.contains(vendorPrefix);
 104     }
 105
 106     private final Map<PcapNetworkInterfaceWrapper, PacketCapturingService> packetCapturingServices = new ConcurrentHashMap<>();
 107
 108     private boolean explicitScanning = false;
 109     private boolean backgroundScanning = false;
 110
 111     public AmazonDashButtonDiscoveryService() {
 112         super(Collections.singleton(DASH_BUTTON_THING_TYPE), DISCOVER_TIMEOUT_SECONDS, false);
 113     }
 114
 115     @Override
 116     protected void startScan() {
 117         explicitScanning = true;
 118         updateListenerRegistry();
 119     }
 120
 121     @Override
 122     protected synchronized void stopScan() {
 123         explicitScanning = false;
 124         updateListenerRegistry();
 125         super.stopScan();
 126     }
 127
 128     @Override
 129     protected void startBackgroundDiscovery() {
 130         backgroundScanning = true;
 131         updateListenerRegistry();
 132     }
 133
 134     @Override
 135     protected void stopBackgroundDiscovery() {
 136         backgroundScanning = false;
 137         updateListenerRegistry();
 138     }
 139
 140     @Override
 141     public void onPcapNetworkInterfaceAdded(final PcapNetworkInterfaceWrapper networkInterface) {
 142         startCapturing(networkInterface);
 143     }
 144
 145     @Override
 146     public void onPcapNetworkInterfaceRemoved(PcapNetworkInterfaceWrapper networkInterface) {
 147         stopCapturing(networkInterface);
 148     }
 149
 150     private void updateListenerRegistry() {
 151         boolean shouldListen = explicitScanning || backgroundScanning;
 152         if (shouldListen) {
 153             PcapNetworkInterfaceService.instance().registerListener(this);
 154             // Start capturing for all network interfaces
 155             final Set<PcapNetworkInterfaceWrapper> networkInterfaces = PcapNetworkInterfaceService.instance()
 156                     .getNetworkInterfaces();
 157             for (PcapNetworkInterfaceWrapper pcapNetworkInterface : networkInterfaces) {
 158                 startCapturing(pcapNetworkInterface);
 159             }
 160         } else {
 161             PcapNetworkInterfaceService.instance().unregisterListener(this);
 162             // Stop capturing for all network interfaces
 163             final Set<PcapNetworkInterfaceWrapper> networkInterfaces = packetCapturingServices.keySet();
 164             for (PcapNetworkInterfaceWrapper pcapNetworkInterface : networkInterfaces) {
 165                 stopCapturing(pcapNetworkInterface);
 166             }
 167         }
 168     }
 169
 170     /**
 171      * Stops capturing for packets for the given {@link PcapNetworkInterface}.
 172      *
 173      * @param pcapNetworkInterface The {@link PcapNetworkInterface} the capturing should be stopped for.
 174      */
 175     private void stopCapturing(final PcapNetworkInterfaceWrapper pcapNetworkInterface) {
 176         final PacketCapturingService packetCapturingService = packetCapturingServices.remove(pcapNetworkInterface);
 177         final String interfaceName = pcapNetworkInterface.getName();
 178         if (packetCapturingService != null) {
 179             packetCapturingService.stopCapturing();
 180             logger.debug("Stopped capturing for {}.", interfaceName);
 181         } else {
 182             logger.warn("No active PacketCapturingService registered for {}.", interfaceName);
 183         }
 184     }
 185
 186     /**
 187      * Starts capturing for packets for the given {@link PcapNetworkInterface}. If the network interface is already
 188      * captured this method returns without doing anything.
 189      *
 190      * @param pcapNetworkInterface The {@link PcapNetworkInterface} to be captured
 191      */
 192     private void startCapturing(final PcapNetworkInterfaceWrapper pcapNetworkInterface) {
 193         if (packetCapturingServices.containsKey(pcapNetworkInterface)) {
 194             // We already have a tracker
 195             return;
 196         }
 197
 198         PacketCapturingService packetCapturingService = new PacketCapturingService(pcapNetworkInterface);
 199
 200         packetCapturingServices.put(pcapNetworkInterface, packetCapturingService);
 201         final String interfaceName = pcapNetworkInterface.getName();
 202         final boolean capturingStarted = packetCapturingService.startCapturing(new PacketCapturingHandler() {
 203
 204             @Override
 205             public void packetCaptured(MacAddress macAddress) {
 206                 String macAdressString = macAddress.toString();
 207
 208                 if (isAmazonVendor(macAdressString)) {
 209                     logger.debug("Captured a packet from {} which seems to be sent from an Amazon Dash Button device.",
 210                             macAdressString);
 211                     ThingUID dashButtonThing = new ThingUID(DASH_BUTTON_THING_TYPE, macAdressString.replace(":", "-"));
 212                     // @formatter:off
 213                     DiscoveryResult discoveryResult = DiscoveryResultBuilder.create(dashButtonThing)
 214                             .withLabel("Dash Button")
 215                             .withRepresentationProperty(macAdressString)
 216                             .withProperty(PROPERTY_MAC_ADDRESS, macAdressString)
 217                             .withProperty(PROPERTY_NETWORK_INTERFACE_NAME, interfaceName)
 218                             .withProperty(PROPERTY_PACKET_INTERVAL, BigDecimal.valueOf(5000))
 219                             .build();
 220                     // @formatter:on
 221                     thingDiscovered(discoveryResult);
 222                 } else {
 223                     logger.trace(
 224                             "Captured a packet from {} which is ignored as it's not on the list of supported vendor prefixes.",
 225                             macAdressString);
 226                 }
 227             }
 228         });
 229         if (capturingStarted) {
 230             logger.debug("Started capturing for {}.", interfaceName);
 231         }
 232     }
 233 }