/**
* 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;
}
