/** * Tries to obtain a mapped/public address for the specified port (possibly by executing a STUN * query). * * @param dst the destination that we'd like to use this address with. * @param port the port whose mapping we are interested in. * @return a public address corresponding to the specified port or null if all attempts to * retrieve such an address have failed. * @throws IOException if an error occurs while stun4j is using sockets. * @throws BindException if the port is already in use. */ public InetSocketAddress getPublicAddressFor(InetAddress dst, int port) throws IOException, BindException { if (!useStun || (dst instanceof Inet6Address)) { logger.debug( "Stun is disabled for destination " + dst + ", skipping mapped address recovery (useStun=" + useStun + ", IPv6@=" + (dst instanceof Inet6Address) + ")."); // we'll still try to bind though so that we could notify the caller // if the port has been taken already. DatagramSocket bindTestSocket = new DatagramSocket(port); bindTestSocket.close(); // if we're here then the port was free. return new InetSocketAddress(getLocalHost(dst), port); } StunAddress mappedAddress = queryStunServer(port); InetSocketAddress result = null; if (mappedAddress != null) result = mappedAddress.getSocketAddress(); else { // Apparently STUN failed. Let's try to temporarily disble it // and use algorithms in getLocalHost(). ... We should probably // eveng think about completely disabling stun, and not only // temporarily. // Bug report - John J. Barton - IBM InetAddress localHost = getLocalHost(dst); result = new InetSocketAddress(localHost, port); } if (logger.isDebugEnabled()) logger.debug("Returning mapping for port:" + port + " as follows: " + result); return result; }