@harvard-library/passport-cas2-strategy

@harvard-library/passport-cas2-strategy

A CAS2 authentication strategy for PassportJS authentication middleware. This code was written based on the code in the passport-cas module and has been adapted specifically for Harvard Library.

Install

$ npm install @harvard-library/passport-cas2-strategy

Configure Strategy

const passport = require('passport');
const Cas2Strategy = require('@harvard-library/passport-cas2-strategy').Strategy;

passport.use(new Cas2Strategy({
  ssoBaseUrl: process.env.CAS_SSO_BASE_URL,
  ssoLoginUrl: process.env.CAS_SSO_LOGIN_URL,
  validateEndpoint: process.env.CAS_VALIDATE_ENDPOINT,
  appServiceUrl: process.env.CAS_APP_SERVICE_URL
}, (user, done) => {

    let email, eppn;

    // Check if all required user object properites were returned by the CAS server
    if (!user || !user.mail) {
      done(`Missing required user properties from the authentication server.`);
      return null;
    } else {
      email = user.mail;
    }

    // Check if email address exists in database here...

    console.log(`Authentication completed successfully ${email}`);

    // Return user object properties
    const payload = {
      EmailAddress: email,
    };

    done(null, payload);
    return null;

  }

));

Authenticate Requests

// GET: '/cas_login'
exports.casLogin = function(req, res, next) {

  passport.authenticate('cas2', function (err, user, info) {
    // Authentication strategy callback
    console.log(`passport.authenticate ${user} ${info}`);

    // Check error
    if (err) {
      console.error(err);
      return res.status(500).json(err);
    }

    /* AUTHENTICATION FAILED */
    // Check if user empty
    if (!user) {
      const message = info ? info : `Authentication failed`;
      // Render server side unauthorized page with error message
      return res.status(401).render('unauthorized', {
        error: true,
        errorMsg: message
      });
    }

    /* AUTHENTICATION SUCCESS */

    // Create session or generate JWT token here...

    // Redirect
    return res.redirect(200, '/');

  })(req, res, next);

}

CAS 2.0 configuration

ssoBaseUrl

• CAS server base URL
• e.g. https://www.example.com

ssoLoginUrl

• CAS server login url
• e.g. https://www.example.com/cas/login

validateEndpoint

• CAS validation endpoint (this will be appended to ssoBaseUrl)
• e.g. /cas/serviceValidate

appServiceUrl

• Application URL
• CAS server must be configured to allow the application service url
• After successful authentication, browser is redirected back to this url
• e.g. https://exampleapp.com/login

License

The MIT License