user authentication libraries for node.js?

Question

If you are looking for an authentication framework for Connect or Express, Passport is worth investigating: https://github.com/jaredhanson/passport

(Disclosure: I'm the developer of Passport)

I developed Passport after investigating both connect-auth and everyauth. While they are both great modules, they didn't suit my needs. I wanted something that was more light-weight and unobtrusive.

Passport is broken down into separate modules, so you can choose to use only what you need (OAuth, only if necessary). Passport also does not mount any routes in your application, giving you the flexibility to decide when and where you want authentication, and hooks to control what happens when authentication succeeds or fails.

For example, here is the two-step process to setup form-based (username and password) authentication:

passport.use(new LocalStrategy(
  function(username, password, done) {
    // Find the user from your DB (MongoDB, CouchDB, other...)
    User.findOne({ username: username, password: password }, function (err, user) {
      done(err, user);
    });
  }
));

app.post('/login', 
  passport.authenticate('local', { failureRedirect: '/login' }),
  function(req, res) {
    // Authentication successful. Redirect home.
    res.redirect('/');
  });

Additional strategies are available for authentication via Facebook, Twitter, etc. Custom strategies can be plugged-in, if necessary.

Session + If

I guess the reason that you haven't found many good libraries is that using a library for authentication is mostly over engineered.

What you are looking for is just a session-binder :) A session with:

if login and user == xxx and pwd == xxx 
   then store an authenticated=true into the session 
if logout destroy session

thats it.

---

I disagree with your conclusion that the connect-auth plugin is the way to go.

I'm using also connect but I do not use connect-auth for two reasons:

1. IMHO breaks connect-auth the very powerful and easy to read onion-ring architecture of connect. A no-go - my opinion :). You can find a very good and short article about how connect works and the onion ring idea here.

2. If you - as written - just want to use a basic or http login with database or file. Connect-auth is way too big. It's more for stuff like OAuth 1.0, OAuth 2.0 & Co

---

A very simple authentication with connect

(It's complete. Just execute it for testing but if you want to use it in production, make sure to use https) (And to be REST-Principle-Compliant you should use a POST-Request instead of a GET-Request b/c you change a state :)

var connect = require('connect');
var urlparser = require('url');

var authCheck = function (req, res, next) {
    url = req.urlp = urlparser.parse(req.url, true);

    // ####
    // Logout
    if ( url.pathname == "/logout" ) {
      req.session.destroy();
    }

    // ####
    // Is User already validated?
    if (req.session && req.session.auth == true) {
      next(); // stop here and pass to the next onion ring of connect
      return;
    }

    // ########
    // Auth - Replace this example with your Database, Auth-File or other things
    // If Database, you need a Async callback...
    if ( url.pathname == "/login" && 
         url.query.name == "max" && 
         url.query.pwd == "herewego"  ) {
      req.session.auth = true;
      next();
      return;
    }

    // ####
    // This user is not authorized. Stop talking to him.
    res.writeHead(403);
    res.end('Sorry you are not authorized.\n\nFor a login use: /login?name=max&pwd=herewego');
    return;
}

var helloWorldContent = function (req, res, next) {
    res.writeHead(200, { 'Content-Type': 'text/plain' });
    res.end('authorized. Walk around :) or use /logout to leave\n\nYou are currently at '+req.urlp.pathname);
}

var server = connect.createServer(
      connect.logger({ format: ':method :url' }),
      connect.cookieParser(),
      connect.session({ secret: 'foobar' }),
      connect.bodyParser(),
      authCheck,
      helloWorldContent
);

server.listen(3000);

NOTE

I wrote this statement over a year ago and have currently no active node projects. So there are may be API-Changes in Express. Please add a comment if I should change anything.

Looks like the connect-auth plugin to the connect middleware is exactly what I need

I'm using express [ http://expressjs.com ] so the connect plugin fits in very nicely since express is subclassed (ok - prototyped) from connect

I was basically looking for the same thing. Specifically, I wanted the following:

1. To use express.js, which wraps Connect's middleware capability
2. "Form based" authentication
3. Granular control over which routes are authenticated
4. A database back-end for users/passwords
5. Use sessions

What I ended up doing was creating my own middleware function check_auth that I pass as an argument to each route I want authenticated. check_auth merely checks the session and if the user is not logged in, then redirects them to the login page, like so:

function check_auth(req, res, next) {

  //  if the user isn't logged in, redirect them to a login page
  if(!req.session.login) {
    res.redirect("/login");
    return; // the buck stops here... we do not call next(), because
            // we don't want to proceed; instead we want to show a login page
  }

  //  the user is logged in, so call next()
  next();
}

Then for each route, I ensure this function is passed as middleware. For example:

app.get('/tasks', check_auth, function(req, res) {
    // snip
});

Finally, we need to actually handle the login process. This is straightforward:

app.get('/login', function(req, res) {
  res.render("login", {layout:false});
});

app.post('/login', function(req, res) {

  // here, I'm using mongoose.js to search for the user in mongodb
  var user_query = UserModel.findOne({email:req.body.email}, function(err, user){
    if(err) {
      res.render("login", {layout:false, locals:{ error:err } });
      return;
    }

    if(!user || user.password != req.body.password) {
      res.render("login",
        {layout:false,
          locals:{ error:"Invalid login!", email:req.body.email }
        }
      );
    } else {
      // successful login; store the session info
      req.session.login = req.body.email;
      res.redirect("/");
    }
  });
});

At any rate, this approach was mostly designed to be flexible and simple. I'm sure there are numerous ways to improve it. If you have any, I'd very much like your feedback.

EDIT: This is a simplified example. In a production system, you'd never want to store & compare passwords in plain text. As a commenter points out, there are libs that can help manage password security.

Also have a look at everyauth if you want third party/social network login integration.

Here is some code for basic authentication from one of my projects. I use it against CouchDB with and additional auth data cache, but I stripped that code.

Wrap an authentication method around you request handling, and provide a second callback for unsuccessfull authentication. The success callback will get the username as an additional parameter. Don't forget to correctly handle requests with wrong or missing credentials in the failure callback:

/**
 * Authenticate a request against this authentication instance.
 * 
 * @param request
 * @param failureCallback
 * @param successCallback
 * @return
 */
Auth.prototype.authenticate = function(request, failureCallback, successCallback)
{
    var requestUsername = "";
    var requestPassword = "";
    if (!request.headers['authorization'])
    {
        failureCallback();
    }
    else
    {
        var auth = this._decodeBase64(request.headers['authorization']);
        if (auth)
        {
            requestUsername = auth.username;
            requestPassword = auth.password;
        }
        else
        {
            failureCallback();
        }
    }


    //TODO: Query your database (don't forget to do so async)


    db.query( function(result)
    {
        if (result.username == requestUsername && result.password == requestPassword)
        {
            successCallback(requestUsername);
        }
        else
        {
            failureCallback();
        }
    });

};


/**
 * Internal method for extracting username and password out of a Basic
 * Authentication header field.
 * 
 * @param headerValue
 * @return
 */
Auth.prototype._decodeBase64 = function(headerValue)
{
    var value;
    if (value = headerValue.match("^Basic\\s([A-Za-z0-9+/=]+)$"))
    {
        var auth = (new Buffer(value[1] || "", "base64")).toString("ascii");
        return {
            username : auth.slice(0, auth.indexOf(':')),
            password : auth.slice(auth.indexOf(':') + 1, auth.length)
        };
    }
    else
    {
        return null;
    }

};

A different take on authentication is Passwordless, a token-based authentication module for express that circumvents the inherent problem of passwords [1]. It's fast to implement, doesn't require too many forms, and offers better security for the average user (full disclosure: I'm the author).

[1]: Passwords are Obsolete