/**
* 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;
}
/**
* Schedule a timer for retransmission.
*
* @throws Exception if message cannot be sent on the socket
*/
public void schedule() throws Exception {
sock.send(message);
/* choose a random between [-1, 1] */
int rand = new Random().nextInt(2) - 1;
timer.schedule(new RetransmissionHandler(), (interval + rand) * 1000);
}
/**
* 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;
}