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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.network.internal.dhcp;
  14
  15 import java.net.SocketException;
  16 import java.util.Map;
  17 import java.util.TreeMap;
  18
  19 import org.eclipse.jdt.annotation.NonNullByDefault;
  20 import org.eclipse.jdt.annotation.Nullable;
  21 import org.slf4j.Logger;
  22 import org.slf4j.LoggerFactory;
  23
  24 /**
  25  * A singleton. IPRequestReceivedCallback objects can register and unregister.
  26  * If the first one is registered and there is no singleton instance, an instance will be created and the
  27  * receiver thread will be started. If the last IPRequestReceivedCallback is removed, the thread will be stopped
  28  * after the receive socket is closed.
  29  * IPRequestReceivedCallback will be called for the address that is registered and matches the
  30  * DHO_DHCP_REQUESTED_ADDRESS address field.
  31  *
  32  * @author David Graeff - Initial contribution
  33  */
  34 @NonNullByDefault
  35 public class DHCPListenService {
  36     static @Nullable DHCPPacketListenerServer instance;
  37     private static Map<String, IPRequestReceivedCallback> registeredListeners = new TreeMap<>();
  38     private static Logger logger = LoggerFactory.getLogger(DHCPListenService.class);
  39
  40     public static synchronized DHCPPacketListenerServer register(String hostAddress,
  41             IPRequestReceivedCallback dhcpListener) throws SocketException {
  42         DHCPPacketListenerServer instance = DHCPListenService.instance;
  43         if (instance == null) {
  44             instance = new DHCPPacketListenerServer((String ipAddress) -> {
  45                 IPRequestReceivedCallback listener = registeredListeners.get(ipAddress);
  46                 if (listener != null) {
  47                     listener.dhcpRequestReceived(ipAddress);
  48                 } else {
  49                     logger.trace("DHCP request for unknown address: {}", ipAddress);
  50                 }
  51             });
  52             DHCPListenService.instance = instance;
  53             instance.start();
  54         }
  55         synchronized (registeredListeners) {
  56             registeredListeners.put(hostAddress, dhcpListener);
  57         }
  58         return instance;
  59     }
  60
  61     public static void unregister(String hostAddress) {
  62         synchronized (registeredListeners) {
  63             registeredListeners.remove(hostAddress);
  64             if (!registeredListeners.isEmpty()) {
  65                 return;
  66             }
  67         }
  68
  69         final DHCPPacketListenerServer instance = DHCPListenService.instance;
  70         if (instance != null) {
  71             instance.close();
  72         }
  73         DHCPListenService.instance = null;
  74     }
  75 }