/**
  * The method queries a Stun server for a binding for the port and address that <tt>sock</tt> is
  * bound on.
  *
  * @param sock the socket whose port and address we'dlike to resolve (the stun message gets sent
  *     trhough that socket)
  * @return StunAddress the address returned by the stun server or null if an error occurred or no
  *     address was returned
  * @throws IOException if an error occurs while stun4j is using sockets.
  * @throws BindException if the port is already in use.
  */
 private StunAddress queryStunServer(DatagramSocket sock) throws IOException, BindException {
   StunAddress mappedAddress = null;
   if (detector != null && useStun) {
     mappedAddress = detector.getMappingFor(sock);
     if (logger.isTraceEnabled()) {
       logger.trace(
           "For socket with address "
               + sock.getLocalAddress().getHostAddress()
               + " and port "
               + sock.getLocalPort()
               + " the stun server returned the "
               + "following mapping ["
               + mappedAddress
               + "]");
     }
   }
   return mappedAddress;
 }
  /**
   * Returns an InetAddress instance that represents the localhost, and that a socket can bind upon
   * or distribute to peers as a contact address.
   *
   * @param intendedDestination the destination that we'd like to use the localhost address with.
   * @return an InetAddress instance representing the local host, and that a socket can bind upon or
   *     distribute to peers as a contact address.
   */
  public synchronized InetAddress getLocalHost(InetAddress intendedDestination) {
    // no point in making sure that the localHostFinderSocket is initialized.
    // better let it through a NullPointerException.
    InetAddress localHost = null;
    localHostFinderSocket.connect(intendedDestination, this.RANDOM_ADDR_DISC_PORT);
    localHost = localHostFinderSocket.getLocalAddress();
    localHostFinderSocket.disconnect();
    // windows socket implementations return the any address so we need to
    // find something else here ... InetAddress.getLocalHost seems to work
    // better on windows so lets hope it'll do the trick.
    if (localHost.isAnyLocalAddress()) {
      try {
        // all that's inside the if is an ugly IPv6 hack
        // (good ol' IPv6 - always causing more problems than it solves.)
        if (intendedDestination instanceof Inet6Address) {
          // return the first globally routable ipv6 address we find
          // on the machine (and hope it's a good one)
          Enumeration interfaces = NetworkInterface.getNetworkInterfaces();

          while (interfaces.hasMoreElements()) {
            NetworkInterface iface = (NetworkInterface) interfaces.nextElement();
            Enumeration addresses = iface.getInetAddresses();
            while (addresses.hasMoreElements()) {
              InetAddress address = (InetAddress) addresses.nextElement();
              if (address instanceof Inet6Address) {
                if (!address.isAnyLocalAddress()
                    && !address.isLinkLocalAddress()
                    && !address.isSiteLocalAddress()
                    && !address.isLoopbackAddress()) {
                  return address;
                }
              }
            }
          }
        } else localHost = InetAddress.getLocalHost();
        /** @todo test on windows for ipv6 cases */
      } catch (Exception ex) {
        // sigh ... ok return 0.0.0.0
        logger.warn("Failed to get localhost ", ex);
      }
    }

    return localHost;
  }