/**
* 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;
}
