{
sess.sendResponse("502 Authentication not supported");
return;
}
AuthenticationHandler authHandler = authFactory.create();
String[] args = this.getArgs(commandString);
// Let's check the command syntax
if (args.length < 2)
{
sess.sendResponse("501 Syntax: " + VERB + " mechanism [initial-response]");
return;
}
// Let's check if we support the required authentication mechanism
String mechanism = args[1];
if (!authFactory.getAuthenticationMechanisms().contains(mechanism.toUpperCase(Locale.ENGLISH)))
{
sess.sendResponse("504 The requested authentication mechanism is not supported");
return;
}
// OK, let's go trough the authentication process.
try
{
// The authentication process may require a series of challenge-responses
CRLFTerminatedReader reader = sess.getReader();
String response = authHandler.auth(commandString);
if (response != null)
{
// challenge-response iteration
sess.sendResponse(response);
}
while (response != null)
{
String clientInput = reader.readLine();
if (clientInput.trim().equals(AUTH_CANCEL_COMMAND))
{
// RFC 2554 explicitly states this:
sess.sendResponse("501 Authentication canceled by client.");
return;
}
else
{
response = authHandler.auth(clientInput);
if (response != null)
{
// challenge-response iteration
sess.sendResponse(response);
}