Develop a Script for External Passcode Validation

/**
* This library defines the following namespaces: SAP, SAP.sample and SAP.util.
* It has to be included before any other library provided by SAP.
*/
var SAP = {
    sample : {},
    util : {}
}

/**
* This library provides an utility class for passcode validation against RSA SecurID server.
* For additional information check the online documentation at http://help.sap.com/saphelp_nwsso20/helpdata/en/2c/c4781832aa4cd9bf5a253aa0ac1445/content.htm
*/
SAP.util.rsa = {

    PasscodeValidator : {

        /**
         * Function to validate RSA passcode against a RSA server.
         * Supports RSA server failover via multiple RADIUS destinations
         *
         *
         * @param  {PolicyConfiguration} config  the configuration used for the current login. Different configuration options can be read and set
         * @param  {PolicyContext} context  policy context for the current login
         * @param  {PasscodeValidationLoginResult} result passcode validation result. End-user messages (warnings, errors, infos) are returned here along with the passcode validation status
         * @param  {String} username username used in the current login
         * @param  {String} passcode passcode to be validated
         * @param  {String[]} [destinations] array with the names of RADIUS destinations for failover support.
         *          When it is null or empty, the RADIUS destination name is taken from the login module option "rsa.login.module.option.RadiusDestination".
         *          When there is no such login module option the default RADIUS destination is used by "SecureLoginModule20RADIUS" login module.
         * @return {boolean} true when the given passcode is valid, false when is not valid or the validation is not possible
         */
        validate: function (config, context, result, username, passcode, destinations) {
            // The type of "logger" is LogAccessor
            var logger = context.getLogger();
            logger.traceDebug("Validating passcode against RSA server for user: " + username);

            // The type of "rsaContext" is RSAContext
           var rsaContext = context.getRsaContext();

            // RSA context is using the login module configured with configuration property "rsa.login.module" and default value "SecureLoginModule20RADIUS" for passcode validation.
            // "passcodeStatus" is of type String with values "VALID_PASSCODE", "INVALID_PASSCODE", "VALID_NEXT_PASSCODE_REQUIRED" or "RSA_SERVICE_UNAVAILABLE".
            var passcodeStatus;

            var processedPasscodeStatus;

            // no failover
            if (typeof destinations == "undefined" || destinations == null || destinations.length == 0) {
                logger.traceInfo("No failover RADIUS destinations are specified.");

                passcodeStatus = rsaContext.validatePasscode(username, passcode);
                processedPasscodeStatus = processPasscodeStatus(passcodeStatus);

                if (processedPasscodeStatus == null) {
                    logger.logError("The RADIUS destination was not available for passcode validation.");
                    result.setValidationFailureWithErrorMessage("Unable to validate RSA SecurID passcode. Contact your system administrator.");
                    return false;
                }
                return processedPasscodeStatus;
            }

            // failover
            logger.traceInfo("Using the following RADIUS destinations: " + destinations);
            var destinationsCount = destinations.length;
            for (var i = 0; i < destinationsCount; i++) {
                if (!destinations[i]) {
                    continue;
                }

                rsaContext.setRADIUSDestination(destinations[i]);

                passcodeStatus = rsaContext.validatePasscode(username, passcode);
                processedPasscodeStatus = processPasscodeStatus(passcodeStatus);
                if (processedPasscodeStatus == null) {
                    continue;
                }

                return processedPasscodeStatus;
            }

            // unsuccessful failover
            logger.logError("None of the configured RADIUS destinations were available for passcode validation.");
            result.setValidationFailureWithErrorMessage("Unable to validate RSA SecurID passcode. Contact your system administrator.");
            return false;



            function processPasscodeStatus(passcodeStatus) {
                switch (passcodeStatus) {
                    // the configured RADIUS server is not available
                    case rsaContext.RSA_SERVICE_UNAVAILABLE: {
                        return null;
                    }

                    // Passcode validation passed successfully.
                    case rsaContext.VALID_PASSCODE:
                    {
                        logger.traceDebug("RSA SecurID passcode is accepted.");
                        result.setValidationSuccessful();
                        return true;
                    }

                    // Passcode is invalid. Issue a warning message.
                    case rsaContext.INVALID_PASSCODE:
                    {
                        logger.traceDebug("Invalid RSA SecurID passcode");
                        // A warning message is displayed on the logon page.
                        result.setValidationFailureWithWarningMessage("Wrong RSA SecurID passcode");
                        return false;
                    }

                    // Provide the next passcode. For example, when several wrong passcodes were entered on previous attempts.
                    case rsaContext.VALID_NEXT_PASSCODE_REQUIRED:
                    {
                        logger.traceDebug("RSA SecurID passcode is accepted. User should provide next one for confirmation");
                        // An information message is displayed on the logon page in case a second passcode is required.
                        result.setValidationFailureWithInfoMessage("RSA SecurID passcode accepted. Enter a second passcode to log on.");
                        return true;
                    }

                    default:
                    {
                        logger.traceDebug("Unknown RSA SecurID passcode status: " + passcodeStatus);
                        result.setValidationFailureWithErrorMessage("Unknown RSA SecurID passcode status. Contact your system administrator.");
                        return false;
                    }
                }
            }
        }
    }
};