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   1 /**
   2  * Copyright (c) 2010-2023 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.capturing;
  14
  15 import java.util.concurrent.ExecutorService;
  16 import java.util.concurrent.Executors;
  17
  18 import org.openhab.binding.amazondashbutton.internal.pcap.PcapNetworkInterfaceWrapper;
  19 import org.pcap4j.core.BpfProgram.BpfCompileMode;
  20 import org.pcap4j.core.NotOpenException;
  21 import org.pcap4j.core.PacketListener;
  22 import org.pcap4j.core.PcapHandle;
  23 import org.pcap4j.core.PcapNetworkInterface.PromiscuousMode;
  24 import org.pcap4j.packet.ArpPacket;
  25 import org.pcap4j.packet.EthernetPacket;
  26 import org.pcap4j.packet.Packet;
  27 import org.pcap4j.packet.UdpPacket;
  28 import org.pcap4j.packet.namednumber.ArpOperation;
  29 import org.pcap4j.packet.namednumber.UdpPort;
  30 import org.pcap4j.util.MacAddress;
  31 import org.slf4j.Logger;
  32 import org.slf4j.LoggerFactory;
  33
  34 /**
  35  * The {@link PacketCapturingService} is responsible for capturing packets.
  36  *
  37  * @author Oliver Libutzki - Initial contribution
  38  *
  39  */
  40 public class PacketCapturingService {
  41
  42     private final Logger logger = LoggerFactory.getLogger(PacketCapturingService.class);
  43
  44     private static final int READ_TIMEOUT = 10; // [ms]
  45     private static final int SNAPLEN = 65536; // [bytes]
  46
  47     private final PcapNetworkInterfaceWrapper pcapNetworkInterface;
  48
  49     private PcapHandle pcapHandle;
  50
  51     public PacketCapturingService(PcapNetworkInterfaceWrapper pcapNetworkInterface) {
  52         this.pcapNetworkInterface = pcapNetworkInterface;
  53     }
  54
  55     /**
  56      * Calls {@link #startCapturing(PacketCapturingHandler, String)} with a null MAC address.
  57      *
  58      * @param packetCapturingHandler The handler to be called every time packet is captured
  59      * @return Returns true, if the capturing has been started successfully, otherwise returns false
  60      */
  61     public boolean startCapturing(final PacketCapturingHandler packetCapturingHandler) {
  62         return startCapturing(packetCapturingHandler, null);
  63     }
  64
  65     /**
  66      * Starts the capturing in a dedicated thread, so this method returns immediately. Every time a packet is captured,
  67      * the {@link PacketCapturingHandler#packetCaptured(MacAddress)} of the given
  68      * {@link PacketCapturingHandler} is called.
  69      *
  70      * It's possible to capture packets sent by a specific MAC address by providing the given parameter. If the
  71      * macAddress is null, all MAC addresses are considered.
  72      *
  73      * @param packetCapturingHandler The handler to be called every time a packet is captured
  74      * @param macAddress The source MAC address of the captured packet, might be null in order to deactivate this filter
  75      *            criteria
  76      * @return Returns true, if the capturing has been started successfully, otherwise returns false
  77      * @throws IllegalStateException Thrown if {@link PcapHandle#isOpen()} of {@link #pcapHandle} returns true
  78      */
  79
  80     public boolean startCapturing(final PacketCapturingHandler packetCapturingHandler, final String macAddress) {
  81         if (pcapHandle != null) {
  82             if (pcapHandle.isOpen()) {
  83                 throw new IllegalStateException("There is an open pcap handle.");
  84             } else {
  85                 pcapHandle.close();
  86             }
  87         }
  88         try {
  89             pcapHandle = pcapNetworkInterface.openLive(SNAPLEN, PromiscuousMode.PROMISCUOUS, READ_TIMEOUT);
  90             StringBuilder filterBuilder = new StringBuilder("(arp or port bootps)");
  91             if (macAddress != null) {
  92                 filterBuilder.append(" and ether src " + macAddress);
  93             }
  94             pcapHandle.setFilter(filterBuilder.toString(), BpfCompileMode.OPTIMIZE);
  95         } catch (Exception e) {
  96             logger.error("Capturing packets on device {} failed.", pcapNetworkInterface.getName(), e);
  97             return false;
  98         }
  99         ExecutorService executorService = Executors.newSingleThreadExecutor();
 100         executorService.submit(() -> {
 101             try {
 102                 pcapHandle.loop(-1, new PacketListener() {
 103
 104                     @Override
 105                     public void gotPacket(Packet packet) {
 106                         if (!packet.contains(EthernetPacket.class)) {
 107                             return;
 108                         }
 109                         final EthernetPacket ethernetPacket = packet.get(EthernetPacket.class);
 110                         final MacAddress sourceMacAddress = ethernetPacket.getHeader().getSrcAddr();
 111                         if (shouldCapture(packet)) {
 112                             packetCapturingHandler.packetCaptured(sourceMacAddress);
 113                         }
 114                     }
 115                 });
 116             } finally {
 117                 if (pcapHandle != null && pcapHandle.isOpen()) {
 118                     pcapHandle.close();
 119                     pcapHandle = null;
 120                 }
 121             }
 122             return null;
 123         });
 124         if (macAddress == null) {
 125             logger.debug("Started capturing ARP and BOOTP requests for network device {}.",
 126                     pcapNetworkInterface.getName());
 127         } else {
 128             logger.debug("Started capturing ARP  and BOOTP requests for network device {} and MAC address {}.",
 129                     pcapNetworkInterface.getName(), macAddress);
 130         }
 131         return true;
 132     }
 133
 134     /**
 135      * Checks if the given {@link Packet} should be captured.
 136      *
 137      * @param packet The packet to be checked
 138      * @return Returns true, if the packet should be captured, otherwise false
 139      */
 140     @SuppressWarnings("PMD.CompareObjectsWithEquals")
 141     private boolean shouldCapture(final Packet packet) {
 142         if (packet.contains(ArpPacket.class)) {
 143             ArpPacket arpPacket = packet.get(ArpPacket.class);
 144             if (arpPacket.getHeader().getOperation().equals(ArpOperation.REQUEST)) {
 145                 return true;
 146             }
 147         }
 148         if (packet.contains(UdpPacket.class)) {
 149             final UdpPacket udpPacket = packet.get(UdpPacket.class);
 150             if (UdpPort.BOOTPS == udpPacket.getHeader().getDstPort()) {
 151                 return true;
 152             }
 153         }
 154         return false;
 155     }
 156
 157     /**
 158      * Stops the capturing. This can be called without calling {@link #startCapturing(PacketCapturingHandler)} or
 159      * {@link #startCapturing(PacketCapturingHandler, String)} before.
 160      */
 161     public void stopCapturing() {
 162         if (pcapHandle != null) {
 163             if (pcapHandle.isOpen()) {
 164                 try {
 165                     pcapHandle.breakLoop();
 166                     logger.debug("Stopped capturing ARP and BOOTP requests for network device {}.",
 167                             pcapNetworkInterface.getName());
 168                 } catch (NotOpenException e) {
 169                     // Just ignore
 170                 }
 171             } else {
 172                 pcapHandle = null;
 173             }
 174         }
 175     }
 176
 177     /**
 178      * Returns the tracked {@link PcapNetworkInterfaceWrapper}.
 179      *
 180      * @return the tracked {@link PcapNetworkInterfaceWrapper}
 181      */
 182     public PcapNetworkInterfaceWrapper getPcapNetworkInterface() {
 183         return pcapNetworkInterface;
 184     }
 185 }