/**
* Notifies this <tt>ResponseCollector</tt> that a transaction described by the specified
* <tt>BaseStunMessageEvent</tt> has failed. The possible reasons for the failure include
* timeouts, unreachable destination, etc.
*
* @param event the <tt>BaseStunMessageEvent</tt> which describes the failed transaction and the
* runtime type of which specifies the failure reason
* @see AbstractResponseCollector#processFailure(BaseStunMessageEvent)
*/
@Override
protected void processFailure(BaseStunMessageEvent event) {
TransactionID transactionID = event.getTransactionID();
logger.finest("A transaction expired: tranid=" + transactionID);
logger.finest("localAddr=" + hostCandidate);
/*
* Clean up for the purposes of the workaround which determines the STUN
* Request to which a STUN Response responds.
*/
Request request;
synchronized (requests) {
request = requests.remove(transactionID);
}
if (request == null) {
Message message = event.getMessage();
if (message instanceof Request) request = (Request) message;
}
boolean completedResolvingCandidate = true;
try {
if (processErrorOrFailure(null, request, transactionID)) completedResolvingCandidate = false;
} finally {
if (completedResolvingCandidate) completedResolvingCandidate(request, null);
}
}
/**
* Creates a <tt>ServerReflexiveCandidate</tt> using {@link #hostCandidate} as its base and the
* <tt>XOR-MAPPED-ADDRESS</tt> attribute in <tt>response</tt> for the actual
* <tt>TransportAddress</tt> of the new candidate. If the message is malformed and/or does not
* contain the corresponding attribute, this method simply has no effect.
*
* @param response the STUN <tt>Response</tt> which is supposed to contain the address we should
* use for the new candidate
*/
protected void createServerReflexiveCandidate(Response response) {
TransportAddress addr = getMappedAddress(response);
if (addr != null) {
ServerReflexiveCandidate srvrRflxCand = createServerReflexiveCandidate(addr);
if (srvrRflxCand != null) {
try {
addCandidate(srvrRflxCand);
} finally {
// Free srvrRflxCand if it has not been consumed.
if (!containsCandidate(srvrRflxCand)) {
try {
srvrRflxCand.free();
} catch (Exception ex) {
if (logger.isLoggable(Level.FINE)) {
logger.log(
Level.FINE,
"Failed to free" + " ServerReflexiveCandidate: " + srvrRflxCand,
ex);
}
}
}
}
}
}
}
/**
* Sends a specific <tt>Request</tt> to the STUN server associated with this
* <tt>StunCandidateHarvest</tt>.
*
* @param request the <tt>Request</tt> to send to the STUN server associated with this
* <tt>StunCandidateHarvest</tt>
* @param firstRequest <tt>true</tt> if the specified <tt>request</tt> should be sent as the first
* request in the terms of STUN; otherwise, <tt>false</tt>
* @return the <tt>TransactionID</tt> of the STUN client transaction through which the specified
* <tt>Request</tt> has been sent to the STUN server associated with this
* <tt>StunCandidateHarvest</tt>
* @param transactionID the <tt>TransactionID</tt> of <tt>request</tt> because <tt>request</tt>
* only has it as a <tt>byte</tt> array and <tt>TransactionID</tt> is required for the
* <tt>applicationData</tt> property value
* @throws StunException if anything goes wrong while sending the specified <tt>Request</tt> to
* the STUN server associated with this <tt>StunCandidateHarvest</tt>
*/
protected TransactionID sendRequest(
Request request, boolean firstRequest, TransactionID transactionID) throws StunException {
if (!firstRequest && (longTermCredentialSession != null))
longTermCredentialSession.addAttributes(request);
StunStack stunStack = harvester.getStunStack();
TransportAddress stunServer = harvester.stunServer;
TransportAddress hostCandidateTransportAddress = hostCandidate.getTransportAddress();
if (transactionID == null) {
byte[] transactionIDAsBytes = request.getTransactionID();
transactionID =
(transactionIDAsBytes == null)
? TransactionID.createNewTransactionID()
: TransactionID.createTransactionID(harvester.getStunStack(), transactionIDAsBytes);
}
synchronized (requests) {
try {
transactionID =
stunStack.sendRequest(
request, stunServer, hostCandidateTransportAddress, this, transactionID);
} catch (IllegalArgumentException iaex) {
if (logger.isLoggable(Level.INFO)) {
logger.log(
Level.INFO,
"Failed to send "
+ request
+ " through "
+ hostCandidateTransportAddress
+ " to "
+ stunServer,
iaex);
}
throw new StunException(StunException.ILLEGAL_ARGUMENT, iaex.getMessage(), iaex);
} catch (IOException ioex) {
if (logger.isLoggable(Level.INFO)) {
logger.log(
Level.INFO,
"Failed to send "
+ request
+ " through "
+ hostCandidateTransportAddress
+ " to "
+ stunServer,
ioex);
}
throw new StunException(StunException.NETWORK_ERROR, ioex.getMessage(), ioex);
}
requests.put(transactionID, request);
}
return transactionID;
}
/**
* Runs in {@link #sendKeepAliveMessageThread} and sends STUN keep-alive <tt>Message</tt>s to the
* STUN server associated with the <tt>StunCandidateHarvester</tt> of this instance.
*
* @return <tt>true</tt> if the method is to be invoked again; otherwise, <tt>false</tt>
*/
private boolean runInSendKeepAliveMessageThread() {
synchronized (sendKeepAliveMessageSyncRoot) {
// Since we're going to #wait, make sure we're not canceled yet.
if (sendKeepAliveMessageThread != Thread.currentThread()) return false;
if (sendKeepAliveMessageInterval == SEND_KEEP_ALIVE_MESSAGE_INTERVAL_NOT_SPECIFIED) {
return false;
}
// Determine the amount of milliseconds that we'll have to #wait.
long timeout;
if (sendKeepAliveMessageTime == -1) {
/*
* If we're just starting, don't just go and send a new STUN
* keep-alive message but rather wait for the whole interval.
*/
timeout = sendKeepAliveMessageInterval;
} else {
timeout =
sendKeepAliveMessageTime + sendKeepAliveMessageInterval - System.currentTimeMillis();
}
// At long last, #wait if necessary.
if (timeout > 0) {
try {
sendKeepAliveMessageSyncRoot.wait(timeout);
} catch (InterruptedException iex) {
}
/*
* Apart from being the time to send the STUN keep-alive
* message, it could be that we've experienced a spurious
* wake-up or that we've been canceled.
*/
return true;
}
}
sendKeepAliveMessageTime = System.currentTimeMillis();
try {
sendKeepAliveMessage();
} catch (StunException sex) {
logger.log(Level.INFO, "Failed to send STUN keep-alive message.", sex);
}
return true;
}
/**
* Notifies this <tt>ResponseCollector</tt> that a STUN response described by the specified
* <tt>StunResponseEvent</tt> has been received.
*
* @param event the <tt>StunResponseEvent</tt> which describes the received STUN response
* @see ResponseCollector#processResponse(StunResponseEvent)
*/
@Override
public void processResponse(StunResponseEvent event) {
TransactionID transactionID = event.getTransactionID();
logger.finest("Received a message: tranid= " + transactionID);
logger.finest("localCand= " + hostCandidate);
/*
* Clean up for the purposes of the workaround which determines the STUN
* Request to which a STUN Response responds.
*/
synchronized (requests) {
requests.remove(transactionID);
}
// At long last, do start handling the received STUN Response.
Response response = event.getResponse();
Request request = event.getRequest();
boolean completedResolvingCandidate = true;
try {
if (response.isSuccessResponse()) {
// Authentication and Message-Integrity Mechanisms
if (request.containsAttribute(Attribute.MESSAGE_INTEGRITY)) {
MessageIntegrityAttribute messageIntegrityAttribute =
(MessageIntegrityAttribute) response.getAttribute(Attribute.MESSAGE_INTEGRITY);
/*
* RFC 5389: If MESSAGE-INTEGRITY was absent, the response
* MUST be discarded, as if it was never received.
*/
if (messageIntegrityAttribute == null) return;
UsernameAttribute usernameAttribute =
(UsernameAttribute) request.getAttribute(Attribute.USERNAME);
/*
* For a request or indication message, the agent MUST
* include the USERNAME and MESSAGE-INTEGRITY attributes in
* the message.
*/
if (usernameAttribute == null) return;
if (!harvester
.getStunStack()
.validateMessageIntegrity(
messageIntegrityAttribute,
LongTermCredential.toString(usernameAttribute.getUsername()),
!request.containsAttribute(Attribute.REALM)
&& !request.containsAttribute(Attribute.NONCE),
event.getRawMessage())) return;
}
processSuccess(response, request, transactionID);
} else {
ErrorCodeAttribute errorCodeAttr =
(ErrorCodeAttribute) response.getAttribute(Attribute.ERROR_CODE);
if ((errorCodeAttr != null) && (errorCodeAttr.getErrorClass() == 4)) {
try {
switch (errorCodeAttr.getErrorNumber()) {
case 1: // 401 Unauthorized
if (processUnauthorized(response, request, transactionID))
completedResolvingCandidate = false;
break;
case 38: // 438 Stale Nonce
if (processStaleNonce(response, request, transactionID))
completedResolvingCandidate = false;
break;
}
} catch (StunException sex) {
completedResolvingCandidate = true;
}
}
if (completedResolvingCandidate && processErrorOrFailure(response, request, transactionID))
completedResolvingCandidate = false;
}
} finally {
if (completedResolvingCandidate) completedResolvingCandidate(request, response);
}
}
/**
* Represents the harvesting of STUN <tt>Candidates</tt> for a specific <tt>HostCandidate</tt>
* performed by a specific <tt>StunCandidateHarvester</tt>.
*
* @author Lyubomir Marinov
*/
public class StunCandidateHarvest extends AbstractResponseCollector {
/**
* The <tt>Logger</tt> used by the <tt>StunCandidateHarvest</tt> class and its instances for
* logging output.
*/
private static final Logger logger = Logger.getLogger(StunCandidateHarvest.class.getName());
/**
* The constant which defines an empty array with <tt>LocalCandidate</tt> element type. Explicitly
* defined in order to reduce unnecessary allocations.
*/
private static final LocalCandidate[] NO_CANDIDATES = new LocalCandidate[0];
/**
* The value of the <tt>sendKeepAliveMessage</tt> property of <tt>StunCandidateHarvest</tt> which
* specifies that no sending of STUN keep-alive messages is to performed for the purposes of
* keeping the <tt>Candidate</tt>s harvested by the <tt>StunCandidateHarvester</tt> in question
* alive.
*/
protected static final long SEND_KEEP_ALIVE_MESSAGE_INTERVAL_NOT_SPECIFIED = 0;
/** The list of <tt>Candidate</tt>s harvested for {@link #hostCandidate} by this harvest. */
private final List<LocalCandidate> candidates = new LinkedList<>();
/**
* The indicator which determines whether this <tt>StunCandidateHarvest</tt> has completed the
* harvesting of <tt>Candidate</tt>s for {@link #hostCandidate}.
*/
private boolean completedResolvingCandidate = false;
/**
* The <tt>StunCandidateHarvester</tt> performing the harvesting of STUN <tt>Candidate</tt>s for a
* <tt>Component</tt> which this harvest is part of.
*/
public final StunCandidateHarvester harvester;
/** The <tt>HostCandidate</tt> the STUN harvesting of which is represented by this instance. */
public final HostCandidate hostCandidate;
/** The <tt>LongTermCredential</tt> used by this instance. */
private LongTermCredentialSession longTermCredentialSession;
/**
* The STUN <tt>Request</tt>s which have been sent by this instance, have not received a STUN
* <tt>Response</tt> yet and have not timed out. Put in place to avoid a limitation of the
* <tt>ResponseCollector</tt> and its use of <tt>StunMessageEvent</tt> which do not make the STUN
* <tt>Request</tt> to which a STUN <tt>Response</tt> responds available though it is known in
* <tt>StunClientTransaction</tt>.
*/
private final Map<TransactionID, Request> requests = new HashMap<>();
/**
* The interval in milliseconds at which a new STUN keep-alive message is to be sent to the STUN
* server associated with the <tt>StunCandidateHarvester</tt> of this instance in order to keep
* one of the <tt>Candidate</tt>s harvested by this instance alive.
*/
private long sendKeepAliveMessageInterval = SEND_KEEP_ALIVE_MESSAGE_INTERVAL_NOT_SPECIFIED;
/**
* The <tt>Object</tt> used to synchronize access to the members related to the sending of STUN
* keep-alive messages to the STUN server associated with the <tt>StunCandidateHarvester</tt> of
* this instance.
*/
private final Object sendKeepAliveMessageSyncRoot = new Object();
/**
* The <tt>Thread</tt> which sends the STUN keep-alive messages to the STUN server associated with
* the <tt>StunCandidateHarvester</tt> of this instance in order to keep the <tt>Candidate</tt>s
* harvested by this instance alive.
*/
private Thread sendKeepAliveMessageThread;
/**
* The time (stamp) in milliseconds of the last call to {@link #sendKeepAliveMessage()} which
* completed without throwing an exception. <b>Note</b>: It doesn't mean that the keep-alive
* message was a STUN <tt>Request</tt> and it received a success STUN <tt>Response</tt>.
*/
private long sendKeepAliveMessageTime = -1;
/**
* Initializes a new <tt>StunCandidateHarvest</tt> which is to represent the harvesting of STUN
* <tt>Candidate</tt>s for a specific <tt>HostCandidate</tt> performed by a specific
* <tt>StunCandidateHarvester</tt>.
*
* @param harvester the <tt>StunCandidateHarvester</tt> which is performing the STUN harvesting
* @param hostCandidate the <tt>HostCandidate</tt> for which STUN <tt>Candidate</tt>s are to be
* harvested
*/
public StunCandidateHarvest(StunCandidateHarvester harvester, HostCandidate hostCandidate) {
this.harvester = harvester;
this.hostCandidate = hostCandidate;
}
/**
* Adds a specific <tt>LocalCandidate</tt> to the list of <tt>LocalCandidate</tt>s harvested for
* {@link #hostCandidate} by this harvest.
*
* @param candidate the <tt>LocalCandidate</tt> to be added to the list of
* <tt>LocalCandidate</tt>s harvested for {@link #hostCandidate} by this harvest
* @return <tt>true</tt> if the list of <tt>LocalCandidate</tt>s changed as a result of the method
* invocation; otherwise, <tt>false</tt>
*/
protected boolean addCandidate(LocalCandidate candidate) {
boolean added;
// try to add the candidate to the component and then only add it to the
// harvest if it wasn't deemed redundant
if (!candidates.contains(candidate)
&& hostCandidate.getParentComponent().addLocalCandidate(candidate)) {
added = candidates.add(candidate);
} else {
added = false;
}
return added;
}
/**
* Adds the <tt>Attribute</tt>s to a specific <tt>Request</tt> which support the STUN short-term
* credential mechanism if the mechanism in question is utilized by this
* <tt>StunCandidateHarvest</tt> (i.e. by the associated <tt>StunCandidateHarvester</tt>).
*
* @param request the <tt>Request</tt> to which to add the <tt>Attribute</tt>s supporting the STUN
* short-term credential mechanism if the mechanism in question is utilized by this
* <tt>StunCandidateHarvest</tt>
* @return <tt>true</tt> if the STUN short-term credential mechanism is actually utilized by this
* <tt>StunCandidateHarvest</tt> for the specified <tt>request</tt>; otherwise, <tt>false</tt>
*/
protected boolean addShortTermCredentialAttributes(Request request) {
String shortTermCredentialUsername = harvester.getShortTermCredentialUsername();
if (shortTermCredentialUsername != null) {
request.putAttribute(AttributeFactory.createUsernameAttribute(shortTermCredentialUsername));
request.putAttribute(
AttributeFactory.createMessageIntegrityAttribute(shortTermCredentialUsername));
return true;
} else return false;
}
/**
* Completes the harvesting of <tt>Candidate</tt>s for {@link #hostCandidate}. Notifies {@link
* #harvester} about the completion of the harvesting of <tt>Candidate</tt> for
* <tt>hostCandidate</tt> performed by this <tt>StunCandidateHarvest</tt>.
*
* @param request the <tt>Request</tt> sent by this <tt>StunCandidateHarvest</tt> with which the
* harvesting of <tt>Candidate</tt>s for <tt>hostCandidate</tt> has completed
* @param response the <tt>Response</tt> received by this <tt>StunCandidateHarvest</tt>, if any,
* with which the harvesting of <tt>Candidate</tt>s for <tt>hostCandidate</tt> has completed
* @return <tt>true</tt> if the harvesting of <tt>Candidate</tt>s for <tt>hostCandidate</tt>
* performed by this <tt>StunCandidateHarvest</tt> has completed; otherwise, <tt>false</tt>
*/
protected boolean completedResolvingCandidate(Request request, Response response) {
if (!completedResolvingCandidate) {
completedResolvingCandidate = true;
try {
if (((response == null) || !response.isSuccessResponse())
&& (longTermCredentialSession != null)) {
harvester
.getStunStack()
.getCredentialsManager()
.unregisterAuthority(longTermCredentialSession);
longTermCredentialSession = null;
}
} finally {
harvester.completedResolvingCandidate(this);
}
}
return completedResolvingCandidate;
}
/**
* Determines whether a specific <tt>LocalCandidate</tt> is contained in the list of
* <tt>LocalCandidate</tt>s harvested for {@link #hostCandidate} by this harvest.
*
* @param candidate the <tt>LocalCandidate</tt> to look for in the list of
* <tt>LocalCandidate</tt>s harvested for {@link #hostCandidate} by this harvest
* @return <tt>true</tt> if the list of <tt>LocalCandidate</tt>s contains the specified
* <tt>candidate</tt>; otherwise, <tt>false</tt>
*/
protected boolean containsCandidate(LocalCandidate candidate) {
if (candidate != null) {
LocalCandidate[] candidates = getCandidates();
if ((candidates != null) && (candidates.length != 0)) {
for (LocalCandidate c : candidates) {
if (candidate.equals(c)) return true;
}
}
}
return false;
}
/**
* Creates new <tt>Candidate</tt>s determined by a specific STUN <tt>Response</tt>.
*
* @param response the received STUN <tt>Response</tt>
*/
protected void createCandidates(Response response) {
createServerReflexiveCandidate(response);
}
/**
* Creates a new STUN <tt>Message</tt> to be sent to the STUN server associated with the
* <tt>StunCandidateHarvester</tt> of this instance in order to keep a specific
* <tt>LocalCandidate</tt> (harvested by this instance) alive.
*
* @param candidate the <tt>LocalCandidate</tt> (harvested by this instance) to create a new
* keep-alive STUN message for
* @return a new keep-alive STUN <tt>Message</tt> for the specified <tt>candidate</tt> or
* <tt>null</tt> if no keep-alive sending is to occur
* @throws StunException if anything goes wrong while creating the new keep-alive STUN
* <tt>Message</tt> for the specified <tt>candidate</tt> or the candidate is of an unsupported
* <tt>CandidateType</tt>
*/
protected Message createKeepAliveMessage(LocalCandidate candidate) throws StunException {
/*
* We'll not be keeping a STUN Binding alive for now. If we decide to in
* the future, we'll have to create a Binding Indication and add support
* for sending it.
*/
if (CandidateType.SERVER_REFLEXIVE_CANDIDATE.equals(candidate.getType())) return null;
else {
throw new StunException(StunException.ILLEGAL_ARGUMENT, "candidate");
}
}
/**
* Creates a new <tt>Request</tt> instance which is to be sent by this
* <tt>StunCandidateHarvest</tt> in order to retry a specific <tt>Request</tt>. For example, the
* long-term credential mechanism dictates that a <tt>Request</tt> is first sent by the client
* without any credential-related attributes, then it gets challenged by the server and the client
* retries the original <tt>Request</tt> with the appropriate credential-related attributes in
* response.
*
* @param request the <tt>Request</tt> which is to be retried by this
* <tt>StunCandidateHarvest</tt>
* @return the new <tt>Request</tt> instance which is to be sent by this
* <tt>StunCandidateHarvest</tt> in order to retry the specified <tt>request</tt>
*/
protected Request createRequestToRetry(Request request) {
switch (request.getMessageType()) {
case Message.BINDING_REQUEST:
return MessageFactory.createBindingRequest();
default:
throw new IllegalArgumentException("request.messageType");
}
}
/**
* Creates a new <tt>Request</tt> which is to be sent to {@link StunCandidateHarvester#stunServer}
* in order to start resolving {@link #hostCandidate}.
*
* @return a new <tt>Request</tt> which is to be sent to {@link StunCandidateHarvester#stunServer}
* in order to start resolving {@link #hostCandidate}
*/
protected Request createRequestToStartResolvingCandidate() {
return MessageFactory.createBindingRequest();
}
/**
* Creates and starts the {@link #sendKeepAliveMessageThread} which is to send STUN keep-alive
* <tt>Message</tt>s to the STUN server associated with the <tt>StunCandidateHarvester</tt> of
* this instance in order to keep the <tt>Candidate</tt>s harvested by this instance alive.
*/
private void createSendKeepAliveMessageThread() {
synchronized (sendKeepAliveMessageSyncRoot) {
Thread t = new SendKeepAliveMessageThread(this);
t.setDaemon(true);
t.setName(getClass().getName() + ".sendKeepAliveMessageThread: " + hostCandidate);
boolean started = false;
sendKeepAliveMessageThread = t;
try {
t.start();
started = true;
} finally {
if (!started && (sendKeepAliveMessageThread == t)) sendKeepAliveMessageThread = null;
}
}
}
/**
* Creates a <tt>ServerReflexiveCandidate</tt> using {@link #hostCandidate} as its base and the
* <tt>XOR-MAPPED-ADDRESS</tt> attribute in <tt>response</tt> for the actual
* <tt>TransportAddress</tt> of the new candidate. If the message is malformed and/or does not
* contain the corresponding attribute, this method simply has no effect.
*
* @param response the STUN <tt>Response</tt> which is supposed to contain the address we should
* use for the new candidate
*/
protected void createServerReflexiveCandidate(Response response) {
TransportAddress addr = getMappedAddress(response);
if (addr != null) {
ServerReflexiveCandidate srvrRflxCand = createServerReflexiveCandidate(addr);
if (srvrRflxCand != null) {
try {
addCandidate(srvrRflxCand);
} finally {
// Free srvrRflxCand if it has not been consumed.
if (!containsCandidate(srvrRflxCand)) {
try {
srvrRflxCand.free();
} catch (Exception ex) {
if (logger.isLoggable(Level.FINE)) {
logger.log(
Level.FINE,
"Failed to free" + " ServerReflexiveCandidate: " + srvrRflxCand,
ex);
}
}
}
}
}
}
}
/**
* Creates a new <tt>ServerReflexiveCandidate</tt> instance which is to represent a specific
* <tt>TransportAddress</tt> harvested through {@link #hostCandidate} and the STUN server
* associated with {@link #harvester}.
*
* @param transportAddress the <tt>TransportAddress</tt> to be represented by the new
* <tt>ServerReflexiveCandidate</tt> instance
* @return a new <tt>ServerReflexiveCandidate</tt> instance which represents the specified
* <tt>TransportAddress</tt> harvested through {@link #hostCandidate} and the STUN server
* associated with {@link #harvester}
*/
protected ServerReflexiveCandidate createServerReflexiveCandidate(
TransportAddress transportAddress) {
return new ServerReflexiveCandidate(
transportAddress,
hostCandidate,
harvester.stunServer,
CandidateExtendedType.STUN_SERVER_REFLEXIVE_CANDIDATE);
}
/**
* Runs in {@link #sendKeepAliveMessageThread} to notify this instance that
* <tt>sendKeepAliveMessageThread</tt> is about to exit.
*/
private void exitSendKeepAliveMessageThread() {
synchronized (sendKeepAliveMessageSyncRoot) {
if (sendKeepAliveMessageThread == Thread.currentThread()) sendKeepAliveMessageThread = null;
/*
* Well, if the currentThread is finishing and this instance is
* still to send keep-alive messages, we'd better start another
* Thread for the purpose to continue the work that the
* currentThread was supposed to carry out.
*/
if ((sendKeepAliveMessageThread == null)
&& (sendKeepAliveMessageInterval != SEND_KEEP_ALIVE_MESSAGE_INTERVAL_NOT_SPECIFIED)) {
createSendKeepAliveMessageThread();
}
}
}
/**
* Gets the number of <tt>Candidate</tt>s harvested for {@link #hostCandidate} during this
* harvest.
*
* @return the number of <tt>Candidate</tt>s harvested for {@link #hostCandidate} during this
* harvest
*/
int getCandidateCount() {
return candidates.size();
}
/**
* Gets the <tt>Candidate</tt>s harvested for {@link #hostCandidate} during this harvest.
*
* @return an array containing the <tt>Candidate</tt>s harvested for {@link #hostCandidate} during
* this harvest
*/
LocalCandidate[] getCandidates() {
return candidates.toArray(NO_CANDIDATES);
}
/**
* Gets the <tt>TransportAddress</tt> specified in the XOR-MAPPED-ADDRESS attribute of a specific
* <tt>Response</tt>.
*
* @param response the <tt>Response</tt> from which the XOR-MAPPED-ADDRESS attribute is to be
* retrieved and its <tt>TransportAddress</tt> value is to be returned
* @return the <tt>TransportAddress</tt> specified in the XOR-MAPPED-ADDRESS attribute of
* <tt>response</tt>
*/
protected TransportAddress getMappedAddress(Response response) {
Attribute attribute = response.getAttribute(Attribute.XOR_MAPPED_ADDRESS);
if (attribute instanceof XorMappedAddressAttribute) {
return ((XorMappedAddressAttribute) attribute).getAddress(response.getTransactionID());
}
// old STUN servers (RFC3489) send MAPPED-ADDRESS address
attribute = response.getAttribute(Attribute.MAPPED_ADDRESS);
if (attribute instanceof MappedAddressAttribute) {
return ((MappedAddressAttribute) attribute).getAddress();
} else return null;
}
/**
* Notifies this <tt>StunCandidateHarvest</tt> that a specific STUN <tt>Request</tt> has been
* challenged for a long-term credential (as the short-term credential mechanism does not utilize
* challenging) in a specific <tt>realm</tt> and with a specific <tt>nonce</tt>.
*
* @param realm the realm in which the specified STUN <tt>Request</tt> has been challenged for a
* long-term credential
* @param nonce the nonce with which the specified STUN <tt>Request</tt> has been challenged for a
* long-term credential
* @param request the STUN <tt>Request</tt> which has been challenged for a long-term credential
* @param requestTransactionID the <tt>TransactionID</tt> of <tt>request</tt> because
* <tt>request</tt> only has it as a <tt>byte</tt> array and <tt>TransactionID</tt> is
* required for the <tt>applicationData</tt> property value
* @return <tt>true</tt> if the challenge has been processed and this
* <tt>StunCandidateHarvest</tt> is to continue processing STUN <tt>Response</tt>s; otherwise,
* <tt>false</tt>
* @throws StunException if anything goes wrong while processing the challenge
*/
private boolean processChallenge(
byte[] realm, byte[] nonce, Request request, TransactionID requestTransactionID)
throws StunException {
UsernameAttribute usernameAttribute =
(UsernameAttribute) request.getAttribute(Attribute.USERNAME);
if (usernameAttribute == null) {
if (longTermCredentialSession == null) {
LongTermCredential longTermCredential = harvester.createLongTermCredential(this, realm);
if (longTermCredential == null) {
// The long-term credential mechanism is not being utilized.
return false;
} else {
longTermCredentialSession = new LongTermCredentialSession(longTermCredential, realm);
harvester
.getStunStack()
.getCredentialsManager()
.registerAuthority(longTermCredentialSession);
}
} else {
/*
* If we're going to use the long-term credential to retry the
* request, the long-term credential should be for the request
* in terms of realm.
*/
if (!longTermCredentialSession.realmEquals(realm)) return false;
}
} else {
/*
* If we sent a USERNAME in our request, then we had the long-term
* credential at the time we sent the request in question.
*/
if (longTermCredentialSession == null) return false;
else {
/*
* If we're going to use the long-term credential to retry the
* request, the long-term credential should be for the request
* in terms of username.
*/
if (!longTermCredentialSession.usernameEquals(usernameAttribute.getUsername()))
return false;
else {
// And it terms of realm, of course.
if (!longTermCredentialSession.realmEquals(realm)) return false;
}
}
}
/*
* The nonce is either becoming known for the first time or being
* updated after the old one has gone stale.
*/
longTermCredentialSession.setNonce(nonce);
Request retryRequest = createRequestToRetry(request);
TransactionID retryRequestTransactionID = null;
if (retryRequest != null) {
if (requestTransactionID != null) {
Object applicationData = requestTransactionID.getApplicationData();
if (applicationData != null) {
byte[] retryRequestTransactionIDAsBytes = retryRequest.getTransactionID();
retryRequestTransactionID =
(retryRequestTransactionIDAsBytes == null)
? TransactionID.createNewTransactionID()
: TransactionID.createTransactionID(
harvester.getStunStack(), retryRequestTransactionIDAsBytes);
retryRequestTransactionID.setApplicationData(applicationData);
}
}
retryRequestTransactionID = sendRequest(retryRequest, false, retryRequestTransactionID);
}
return (retryRequestTransactionID != null);
}
/**
* Notifies this <tt>StunCandidateHarvest</tt> that a specific STUN <tt>Response</tt> has been
* received and it challenges a specific STUN <tt>Request</tt> for a long-term credential (as the
* short-term credential mechanism does not utilize challenging).
*
* @param response the STUN <tt>Response</tt> which has been received
* @param request the STUN <tt>Request</tt> to which <tt>response</tt> responds and which it
* challenges for a long-term credential
* @return <tt>true</tt> if the challenge has been processed and this
* <tt>StunCandidateHarvest</tt> is to continue processing STUN <tt>Response</tt>s; otherwise,
* <tt>false</tt>
* @param transactionID the <tt>TransactionID</tt> of <tt>response</tt> and <tt>request</tt>
* because <tt>response</tt> and <tt>request</tt> only have it as a <tt>byte</tt> array and
* <tt>TransactionID</tt> is required for the <tt>applicationData</tt> property value
* @throws StunException if anything goes wrong while processing the challenge
*/
private boolean processChallenge(Response response, Request request, TransactionID transactionID)
throws StunException {
boolean retried = false;
if (response.getAttributeCount() > 0) {
/*
* The response SHOULD NOT contain a USERNAME or
* MESSAGE-INTEGRITY attribute.
*/
char[] excludedResponseAttributeTypes =
new char[] {Attribute.USERNAME, Attribute.MESSAGE_INTEGRITY};
boolean challenge = true;
for (char excludedResponseAttributeType : excludedResponseAttributeTypes) {
if (response.containsAttribute(excludedResponseAttributeType)) {
challenge = false;
break;
}
}
if (challenge) {
// This response MUST include a REALM value.
RealmAttribute realmAttribute = (RealmAttribute) response.getAttribute(Attribute.REALM);
if (realmAttribute == null) challenge = false;
else {
// The response MUST include a NONCE.
NonceAttribute nonceAttribute = (NonceAttribute) response.getAttribute(Attribute.NONCE);
if (nonceAttribute == null) challenge = false;
else {
retried =
processChallenge(
realmAttribute.getRealm(), nonceAttribute.getNonce(), request, transactionID);
}
}
}
}
return retried;
}
/**
* Notifies this <tt>StunCandidateHarvest</tt> that a specific <tt>Request</tt> has either
* received an error <tt>Response</tt> or has failed to receive any <tt>Response</tt>. Allows
* extenders to override and process unhandled error <tt>Response</tt>s or failures. The default
* implementation does no processing.
*
* @param response the error <tt>Response</tt> which has been received for <tt>request</tt>
* @param request the <tt>Request</tt> to which <tt>Response</tt> responds
* @param transactionID the <tt>TransactionID</tt> of <tt>response</tt> and <tt>request</tt>
* because <tt>response</tt> and <tt>request</tt> only have it as a <tt>byte</tt> array and
* <tt>TransactionID</tt> is required for the <tt>applicationData</tt> property value
* @return <tt>true</tt> if the error or failure condition has been processed and this instance
* can continue its execution (e.g. the resolution of the candidate) as if it was expected;
* otherwise, <tt>false</tt>
*/
protected boolean processErrorOrFailure(
Response response, Request request, TransactionID transactionID) {
return false;
}
/**
* Notifies this <tt>ResponseCollector</tt> that a transaction described by the specified
* <tt>BaseStunMessageEvent</tt> has failed. The possible reasons for the failure include
* timeouts, unreachable destination, etc.
*
* @param event the <tt>BaseStunMessageEvent</tt> which describes the failed transaction and the
* runtime type of which specifies the failure reason
* @see AbstractResponseCollector#processFailure(BaseStunMessageEvent)
*/
@Override
protected void processFailure(BaseStunMessageEvent event) {
TransactionID transactionID = event.getTransactionID();
logger.finest("A transaction expired: tranid=" + transactionID);
logger.finest("localAddr=" + hostCandidate);
/*
* Clean up for the purposes of the workaround which determines the STUN
* Request to which a STUN Response responds.
*/
Request request;
synchronized (requests) {
request = requests.remove(transactionID);
}
if (request == null) {
Message message = event.getMessage();
if (message instanceof Request) request = (Request) message;
}
boolean completedResolvingCandidate = true;
try {
if (processErrorOrFailure(null, request, transactionID)) completedResolvingCandidate = false;
} finally {
if (completedResolvingCandidate) completedResolvingCandidate(request, null);
}
}
/**
* Notifies this <tt>ResponseCollector</tt> that a STUN response described by the specified
* <tt>StunResponseEvent</tt> has been received.
*
* @param event the <tt>StunResponseEvent</tt> which describes the received STUN response
* @see ResponseCollector#processResponse(StunResponseEvent)
*/
@Override
public void processResponse(StunResponseEvent event) {
TransactionID transactionID = event.getTransactionID();
logger.finest("Received a message: tranid= " + transactionID);
logger.finest("localCand= " + hostCandidate);
/*
* Clean up for the purposes of the workaround which determines the STUN
* Request to which a STUN Response responds.
*/
synchronized (requests) {
requests.remove(transactionID);
}
// At long last, do start handling the received STUN Response.
Response response = event.getResponse();
Request request = event.getRequest();
boolean completedResolvingCandidate = true;
try {
if (response.isSuccessResponse()) {
// Authentication and Message-Integrity Mechanisms
if (request.containsAttribute(Attribute.MESSAGE_INTEGRITY)) {
MessageIntegrityAttribute messageIntegrityAttribute =
(MessageIntegrityAttribute) response.getAttribute(Attribute.MESSAGE_INTEGRITY);
/*
* RFC 5389: If MESSAGE-INTEGRITY was absent, the response
* MUST be discarded, as if it was never received.
*/
if (messageIntegrityAttribute == null) return;
UsernameAttribute usernameAttribute =
(UsernameAttribute) request.getAttribute(Attribute.USERNAME);
/*
* For a request or indication message, the agent MUST
* include the USERNAME and MESSAGE-INTEGRITY attributes in
* the message.
*/
if (usernameAttribute == null) return;
if (!harvester
.getStunStack()
.validateMessageIntegrity(
messageIntegrityAttribute,
LongTermCredential.toString(usernameAttribute.getUsername()),
!request.containsAttribute(Attribute.REALM)
&& !request.containsAttribute(Attribute.NONCE),
event.getRawMessage())) return;
}
processSuccess(response, request, transactionID);
} else {
ErrorCodeAttribute errorCodeAttr =
(ErrorCodeAttribute) response.getAttribute(Attribute.ERROR_CODE);
if ((errorCodeAttr != null) && (errorCodeAttr.getErrorClass() == 4)) {
try {
switch (errorCodeAttr.getErrorNumber()) {
case 1: // 401 Unauthorized
if (processUnauthorized(response, request, transactionID))
completedResolvingCandidate = false;
break;
case 38: // 438 Stale Nonce
if (processStaleNonce(response, request, transactionID))
completedResolvingCandidate = false;
break;
}
} catch (StunException sex) {
completedResolvingCandidate = true;
}
}
if (completedResolvingCandidate && processErrorOrFailure(response, request, transactionID))
completedResolvingCandidate = false;
}
} finally {
if (completedResolvingCandidate) completedResolvingCandidate(request, response);
}
}
/**
* Handles a specific STUN error <tt>Response</tt> with error code "438 Stale Nonce" to a specific
* STUN <tt>Request</tt>.
*
* @param response the received STUN error <tt>Response</tt> with error code "438 Stale Nonce"
* which is to be handled
* @param request the STUN <tt>Request</tt> to which <tt>response</tt> responds
* @param transactionID the <tt>TransactionID</tt> of <tt>response</tt> and <tt>request</tt>
* because <tt>response</tt> and <tt>request</tt> only have it as a <tt>byte</tt> array and
* <tt>TransactionID</tt> is required for the <tt>applicationData</tt> property value
* @return <tt>true</tt> if the specified STUN error <tt>response</tt> was successfully handled;
* <tt>false</tt>, otherwise
* @throws StunException if anything goes wrong while handling the specified "438 Stale Nonce"
* error <tt>response</tt>
*/
private boolean processStaleNonce(Response response, Request request, TransactionID transactionID)
throws StunException {
/*
* The request MUST contain USERNAME, REALM, NONCE and MESSAGE-INTEGRITY
* attributes.
*/
boolean challenge;
if (request.getAttributeCount() > 0) {
char[] includedRequestAttributeTypes =
new char[] {
Attribute.USERNAME, Attribute.REALM, Attribute.NONCE, Attribute.MESSAGE_INTEGRITY
};
challenge = true;
for (char includedRequestAttributeType : includedRequestAttributeTypes) {
if (!request.containsAttribute(includedRequestAttributeType)) {
challenge = false;
break;
}
}
} else challenge = false;
return (challenge && processChallenge(response, request, transactionID));
}
/**
* Handles a specific STUN success <tt>Response</tt> to a specific STUN <tt>Request</tt>.
*
* @param response the received STUN success <tt>Response</tt> which is to be handled
* @param request the STUN <tt>Request</tt> to which <tt>response</tt> responds
* @param transactionID the <tt>TransactionID</tt> of <tt>response</tt> and <tt>request</tt>
* because <tt>response</tt> and <tt>request</tt> only have it as a <tt>byte</tt> array and
* <tt>TransactionID</tt> is required for the <tt>applicationData</tt> property value
*/
protected void processSuccess(Response response, Request request, TransactionID transactionID) {
if (!completedResolvingCandidate) createCandidates(response);
}
/**
* Handles a specific STUN error <tt>Response</tt> with error code "401 Unauthorized" to a
* specific STUN <tt>Request</tt>.
*
* @param response the received STUN error <tt>Response</tt> with error code "401 Unauthorized"
* which is to be handled
* @param request the STUN <tt>Request</tt> to which <tt>response</tt> responds
* @param transactionID the <tt>TransactionID</tt> of <tt>response</tt> and <tt>request</tt>
* because <tt>response</tt> and <tt>request</tt> only have it as a <tt>byte</tt> array and
* <tt>TransactionID</tt> is required for the <tt>applicationData</tt> property value
* @return <tt>true</tt> if the specified STUN error <tt>response</tt> was successfully handled;
* <tt>false</tt>, otherwise
* @throws StunException if anything goes wrong while handling the specified "401 Unauthorized"
* error <tt>response</tt>
*/
private boolean processUnauthorized(
Response response, Request request, TransactionID transactionID) throws StunException {
/*
* If the response is a challenge, retry the request with a new
* transaction.
*/
boolean challenge = true;
/*
* The client SHOULD omit the USERNAME, MESSAGE-INTEGRITY, REALM, and
* NONCE attributes from the "First Request".
*/
if (request.getAttributeCount() > 0) {
char[] excludedRequestAttributeTypes =
new char[] {
Attribute.USERNAME, Attribute.MESSAGE_INTEGRITY, Attribute.REALM, Attribute.NONCE
};
for (char excludedRequestAttributeType : excludedRequestAttributeTypes) {
if (request.containsAttribute(excludedRequestAttributeType)) {
challenge = false;
break;
}
}
}
return (challenge && processChallenge(response, request, transactionID));
}
/**
* Runs in {@link #sendKeepAliveMessageThread} and sends STUN keep-alive <tt>Message</tt>s to the
* STUN server associated with the <tt>StunCandidateHarvester</tt> of this instance.
*
* @return <tt>true</tt> if the method is to be invoked again; otherwise, <tt>false</tt>
*/
private boolean runInSendKeepAliveMessageThread() {
synchronized (sendKeepAliveMessageSyncRoot) {
// Since we're going to #wait, make sure we're not canceled yet.
if (sendKeepAliveMessageThread != Thread.currentThread()) return false;
if (sendKeepAliveMessageInterval == SEND_KEEP_ALIVE_MESSAGE_INTERVAL_NOT_SPECIFIED) {
return false;
}
// Determine the amount of milliseconds that we'll have to #wait.
long timeout;
if (sendKeepAliveMessageTime == -1) {
/*
* If we're just starting, don't just go and send a new STUN
* keep-alive message but rather wait for the whole interval.
*/
timeout = sendKeepAliveMessageInterval;
} else {
timeout =
sendKeepAliveMessageTime + sendKeepAliveMessageInterval - System.currentTimeMillis();
}
// At long last, #wait if necessary.
if (timeout > 0) {
try {
sendKeepAliveMessageSyncRoot.wait(timeout);
} catch (InterruptedException iex) {
}
/*
* Apart from being the time to send the STUN keep-alive
* message, it could be that we've experienced a spurious
* wake-up or that we've been canceled.
*/
return true;
}
}
sendKeepAliveMessageTime = System.currentTimeMillis();
try {
sendKeepAliveMessage();
} catch (StunException sex) {
logger.log(Level.INFO, "Failed to send STUN keep-alive message.", sex);
}
return true;
}
/**
* Sends a new STUN <tt>Message</tt> to the STUN server associated with the
* <tt>StunCandidateHarvester</tt> of this instance in order to keep a <tt>LocalCandidate</tt>
* harvested by this instance alive.
*
* @throws StunException if anything goes wrong while sending a new keep-alive STUN
* <tt>Message</tt>
*/
protected void sendKeepAliveMessage() throws StunException {
for (LocalCandidate candidate : getCandidates()) if (sendKeepAliveMessage(candidate)) break;
}
/**
* Sends a new STUN <tt>Message</tt> to the STUN server associated with the
* <tt>StunCandidateHarvester</tt> of this instance in order to keep a specific
* <tt>LocalCandidate</tt> alive.
*
* @param candidate the <tt>LocalCandidate</tt> to send a new keep-alive STUN <tt>Message</tt> for
* @return <tt>true</tt> if a new STUN <tt>Message</tt> was sent to the STUN server associated
* with the <tt>StunCandidateHarvester</tt> of this instance or <tt>false</tt> if the STUN
* kee-alive functionality was not been used for the specified <tt>candidate</tt>
* @throws StunException if anything goes wrong while sending the new keep-alive STUN
* <tt>Message</tt> for the specified <tt>candidate</tt>
*/
protected boolean sendKeepAliveMessage(LocalCandidate candidate) throws StunException {
Message keepAliveMessage = createKeepAliveMessage(candidate);
/*
* The #createKeepAliveMessage method javadoc says it returns null when
* the STUN keep-alive functionality of this StunCandidateHarvest is to
* not be utilized.
*/
if (keepAliveMessage == null) {
return false;
} else if (keepAliveMessage instanceof Request) {
return (sendRequest((Request) keepAliveMessage, false, null) != null);
} else {
throw new StunException(
StunException.ILLEGAL_ARGUMENT,
"Failed to create keep-alive STUN message for candidate: " + candidate);
}
}
/**
* Sends a specific <tt>Request</tt> to the STUN server associated with this
* <tt>StunCandidateHarvest</tt>.
*
* @param request the <tt>Request</tt> to send to the STUN server associated with this
* <tt>StunCandidateHarvest</tt>
* @param firstRequest <tt>true</tt> if the specified <tt>request</tt> should be sent as the first
* request in the terms of STUN; otherwise, <tt>false</tt>
* @return the <tt>TransactionID</tt> of the STUN client transaction through which the specified
* <tt>Request</tt> has been sent to the STUN server associated with this
* <tt>StunCandidateHarvest</tt>
* @param transactionID the <tt>TransactionID</tt> of <tt>request</tt> because <tt>request</tt>
* only has it as a <tt>byte</tt> array and <tt>TransactionID</tt> is required for the
* <tt>applicationData</tt> property value
* @throws StunException if anything goes wrong while sending the specified <tt>Request</tt> to
* the STUN server associated with this <tt>StunCandidateHarvest</tt>
*/
protected TransactionID sendRequest(
Request request, boolean firstRequest, TransactionID transactionID) throws StunException {
if (!firstRequest && (longTermCredentialSession != null))
longTermCredentialSession.addAttributes(request);
StunStack stunStack = harvester.getStunStack();
TransportAddress stunServer = harvester.stunServer;
TransportAddress hostCandidateTransportAddress = hostCandidate.getTransportAddress();
if (transactionID == null) {
byte[] transactionIDAsBytes = request.getTransactionID();
transactionID =
(transactionIDAsBytes == null)
? TransactionID.createNewTransactionID()
: TransactionID.createTransactionID(harvester.getStunStack(), transactionIDAsBytes);
}
synchronized (requests) {
try {
transactionID =
stunStack.sendRequest(
request, stunServer, hostCandidateTransportAddress, this, transactionID);
} catch (IllegalArgumentException iaex) {
if (logger.isLoggable(Level.INFO)) {
logger.log(
Level.INFO,
"Failed to send "
+ request
+ " through "
+ hostCandidateTransportAddress
+ " to "
+ stunServer,
iaex);
}
throw new StunException(StunException.ILLEGAL_ARGUMENT, iaex.getMessage(), iaex);
} catch (IOException ioex) {
if (logger.isLoggable(Level.INFO)) {
logger.log(
Level.INFO,
"Failed to send "
+ request
+ " through "
+ hostCandidateTransportAddress
+ " to "
+ stunServer,
ioex);
}
throw new StunException(StunException.NETWORK_ERROR, ioex.getMessage(), ioex);
}
requests.put(transactionID, request);
}
return transactionID;
}
/**
* Sets the interval in milliseconds at which a new STUN keep-alive message is to be sent to the
* STUN server associated with the <tt>StunCandidateHarvester</tt> of this instance in order to
* keep one of the <tt>Candidate</tt>s harvested by this instance alive.
*
* @param sendKeepAliveMessageInterval the interval in milliseconds at which a new STUN keep-alive
* message is to be sent to the STUN server associated with the
* <tt>StunCandidateHarvester</tt> of this instance in order to keep one of the
* <tt>Candidate</tt>s harvested by this instance alive or {@link
* #SEND_KEEP_ALIVE_MESSAGE_INTERVAL_NOT_SPECIFIED} if the keep-alive functionality is to not
* be utilized
*/
protected void setSendKeepAliveMessageInterval(long sendKeepAliveMessageInterval) {
if ((sendKeepAliveMessageInterval != SEND_KEEP_ALIVE_MESSAGE_INTERVAL_NOT_SPECIFIED)
&& (sendKeepAliveMessageInterval < 1))
throw new IllegalArgumentException("sendKeepAliveMessageInterval");
synchronized (sendKeepAliveMessageSyncRoot) {
this.sendKeepAliveMessageInterval = sendKeepAliveMessageInterval;
if (sendKeepAliveMessageThread == null) {
if (this.sendKeepAliveMessageInterval != SEND_KEEP_ALIVE_MESSAGE_INTERVAL_NOT_SPECIFIED)
createSendKeepAliveMessageThread();
} else sendKeepAliveMessageSyncRoot.notify();
}
}
/**
* Starts the harvesting of <tt>Candidate</tt>s to be performed for {@link #hostCandidate}.
*
* @return <tt>true</tt> if this <tt>StunCandidateHarvest</tt> has started the harvesting of
* <tt>Candidate</tt>s for {@link #hostCandidate}; otherwise, <tt>false</tt>
* @throws Exception if anything goes wrong while starting the harvesting of <tt>Candidate</tt>s
* to be performed for {@link #hostCandidate}
*/
boolean startResolvingCandidate() throws Exception {
Request requestToStartResolvingCandidate;
if (!completedResolvingCandidate
&& ((requestToStartResolvingCandidate = createRequestToStartResolvingCandidate())
!= null)) {
// Short-Term Credential Mechanism
addShortTermCredentialAttributes(requestToStartResolvingCandidate);
sendRequest(requestToStartResolvingCandidate, true, null);
return true;
} else return false;
}
/** Close the harvest. */
public void close() {
// stop keep alive thread
setSendKeepAliveMessageInterval(SEND_KEEP_ALIVE_MESSAGE_INTERVAL_NOT_SPECIFIED);
}
/**
* Sends STUN keep-alive <tt>Message</tt>s to the STUN server associated with the
* <tt>StunCandidateHarvester</tt> of this instance.
*
* @author Lyubomir Marinov
*/
private static class SendKeepAliveMessageThread extends Thread {
/**
* The <tt>StunCandidateHarvest</tt> which has initialized this instance. The
* <tt>StunCandidateHarvest</tt> is referenced by a <tt>WeakReference</tt> in an attempt to
* reduce the risk that the <tt>Thread</tt> may live regardless of the fact that the specified
* <tt>StunCandidateHarvest<tt> may no longer be reachable.
*/
private final WeakReference<StunCandidateHarvest> harvest;
/**
* Initializes a new <tt>SendKeepAliveMessageThread</tt> instance with a specific
* <tt>StunCandidateHarvest</tt>.
*
* @param harvest the <tt>StunCandidateHarvest</tt> to initialize the new instance with
*/
public SendKeepAliveMessageThread(StunCandidateHarvest harvest) {
this.harvest = new WeakReference<>(harvest);
}
@Override
public void run() {
try {
do {
StunCandidateHarvest harvest = this.harvest.get();
if ((harvest == null) || !harvest.runInSendKeepAliveMessageThread()) {
break;
}
} while (true);
} finally {
StunCandidateHarvest harvest = this.harvest.get();
if (harvest != null) harvest.exitSendKeepAliveMessageThread();
}
}
}
}