case CHALLENGE:
try {
if (log.isTraceEnabled())
log.trace("%s: received CHALLENGE from %s", getAddress(), remoteAddress);
// the response computed can be null if the challenge-response cycle has ended
Message response = saslContext.nextMessage(remoteAddress, saslHeader);
if (response != null) {
if (log.isTraceEnabled())
log.trace("%s: sending RESPONSE to %s", getAddress(), remoteAddress);
down_prot.down(new Event(Event.MSG, response));
} else {