/**
    *
    */
   package javax.jmdns.impl;
   
   import java.lang.reflect.Method;
   import java.net.InetAddress;
   import java.net.NetworkInterface;
   import java.net.SocketException;
  import java.util.Enumeration;
  import java.util.HashSet;
  import java.util.Set;
  import java.util.logging.Level;
  import java.util.logging.Logger;
  
  import javax.jmdns.NetworkTopologyDiscovery;
  
  /**
   * This class implements NetworkTopologyDiscovery.
   *
   * @author Pierre Frisch
   */
  public class NetworkTopologyDiscoveryImpl implements NetworkTopologyDiscovery {
      private final static Logger logger = Logger.getLogger(NetworkTopologyDiscoveryImpl.class.getName());
  
      private final Method        _isUp;
  
      private final Method        _supportsMulticast;
  
      /**
       *
       */
      public NetworkTopologyDiscoveryImpl() {
          super();
          Method isUp;
          try {
              isUp = NetworkInterface.class.getMethod("isUp", (Class<?>[]) null);
          } catch (Exception exception) {
              // We do not want to throw anything if the method does not exist.
              isUp = null;
          }
          _isUp = isUp;
          Method supportsMulticast;
          try {
              supportsMulticast = NetworkInterface.class.getMethod("supportsMulticast", (Class<?>[]) null);
          } catch (Exception exception) {
              // We do not want to throw anything if the method does not exist.
              supportsMulticast = null;
          }
          _supportsMulticast = supportsMulticast;
      }
  
      /*
       * (non-Javadoc)
       * @see javax.jmdns.JmmDNS.NetworkTopologyDiscovery#getInetAddresses()
       */
      @Override
      public InetAddress[] getInetAddresses() {
          Set<InetAddress> result = new HashSet<InetAddress>();
          try {
  
              for (Enumeration<NetworkInterface> nifs = NetworkInterface.getNetworkInterfaces(); nifs.hasMoreElements();) {
                  NetworkInterface nif = nifs.nextElement();
                  for (Enumeration<InetAddress> iaenum = nif.getInetAddresses(); iaenum.hasMoreElements();) {
                      InetAddress interfaceAddress = iaenum.nextElement();
                      if (logger.isLoggable(Level.FINEST)) {
                          logger.finest("Found NetworkInterface/InetAddress: " + nif + " -- " + interfaceAddress);
                      }
                      if (this.useInetAddress(nif, interfaceAddress)) {
                          result.add(interfaceAddress);
                      }
                  }
              }
          } catch (SocketException se) {
              logger.warning("Error while fetching network interfaces addresses: " + se);
          }
          return result.toArray(new InetAddress[result.size()]);
      }
  
      /*
       * (non-Javadoc)
       * @see javax.jmdns.JmmDNS.NetworkTopologyDiscovery#useInetAddress(java.net.NetworkInterface, java.net.InetAddress)
       */
      @Override
      public boolean useInetAddress(NetworkInterface networkInterface, InetAddress interfaceAddress) {
          try {
              if (_isUp != null) {
                  try {
                      if (!((Boolean) _isUp.invoke(networkInterface, (Object[]) null)).booleanValue()) {
                          return false;
                      }
                  } catch (Exception exception) {
                      // We should hide that exception.
                  }
              }
              if (_supportsMulticast != null) {
                  try {
                      if (!((Boolean) _supportsMulticast.invoke(networkInterface, (Object[]) null)).booleanValue()) {
                          return false;
                     }
                 } catch (Exception exception) {
                     // We should hide that exception.
                 }
             }
             if (interfaceAddress.isLoopbackAddress()) {
                 return false;
             }
             return true;
         } catch (Exception exception) {
             return false;
         }
     }
 
     /*
      * (non-Javadoc)
      * @see javax.jmdns.NetworkTopologyDiscovery#lockInetAddress(java.net.InetAddress)
      */
     @Override
     public void lockInetAddress(InetAddress interfaceAddress) {
         // Default implementation does nothing.
     }
 
     /*
      * (non-Javadoc)
      * @see javax.jmdns.NetworkTopologyDiscovery#unlockInetAddress(java.net.InetAddress)
      */
     @Override
     public void unlockInetAddress(InetAddress interfaceAddress) {
         // Default implementation does nothing.
     }
 
 }