How to Refresh Firebase Session Cookie

Question

I'm developing a web application using Node.js/Express.js for the backend and I use Firebase for user authentication, and to manage user registration etc I use Firebase Admin SDK.

When a user want to login I sign him in using Firebase Client SDK like this:

// Handling User SignIn
$('#signin').on('click', function(e){
    e.preventDefault();

    let form = $('#signin-form'),
        email = form.find('#email').val(),
        pass = form.find('#password').val(),
        errorWrapper = form.find('.error-wrapper');

    if(email && pass){
        firebase.auth().signInWithEmailAndPassword(email, pass)
            .catch(err => {
                showError(errorWrapper, err.code)
            });
    }else {
        showError(errorWrapper, 'auth/required');
    }
});

Below this code, I set an observer to watch for when the user successfully sign in, After a successfull sign in I get a Firebase ID token which I send to an endpoint on the server to exchange it for a session cookie that has the same claims the ID token since the later expires after 1 hour.

// POST to session login endpoint.
let postIdTokenToSessionLogin = function(url, idToken, csrfToken) {
    return $.ajax({
        type: 'POST',
        url: url,
        data: {
            idToken: idToken,
            csrfToken: csrfToken
        },
        contentType: 'application/x-www-form-urlencoded'
    });
};

// Handling SignedIn Users 
firebase.auth().onAuthStateChanged(function(user) {
    if (user) {
        user.getIdToken().then(function(idToken) {
            let csrfToken = getCookie('csrfToken');
            return postIdTokenToSessionLogin('/auth/signin', idToken, csrfToken)
                .then(() => {
                        location.href = '/dashboard';
                    }).catch(err => {
                        location.href = '/signin';
                    });
                });
        });
    } else {
        // No user is signed in.
    }
});

Sign in endpoint on the server looks like this:

// Session signin endpoint.
router.post('/auth/signin', (req, res) => {
    // Omitted Code...
    firebase.auth().verifyIdToken(idToken).then(decodedClaims => {
        return firebase.auth().createSessionCookie(idToken, {
            expiresIn
        });
    }).then(sessionCookie => {
        // Omitted Code...
        res.cookie('session', sessionCookie, options);
        res.end(JSON.stringify({
            status: 'success'
        }));
    }).catch(err => {
        res.status(401).send('UNAUTHORIZED REQUEST!');
    });
});

I have created a middle ware to verify user session cookie before giving him access to protected content that looks like this:

function isAuthenticated(auth) {
    return (req, res, next) => {
        let sessionCookie = req.cookies.session || '';
        firebase.auth().verifySessionCookie(sessionCookie, true).then(decodedClaims => {
            if (auth) {
                return res.redirect('/dashboard')
            } else {
                res.locals.user = decodedClaims;
                next();
            }
        }).catch(err => {
            if (auth) next();
            else return res.redirect('/signin')
        });
    }
}

To show user information on the view I set the decoded claims on res.locals.user variable and pass it to the next middle ware where I render the view and passing that variable like this.

router.get('/', (req, res) => {
    res.render('dashboard/settings', {
        user: res.locals.user
    });
});

So far everything is fine, now the problem comes after the user go to his dashboard to change his information (name and email), when he submits the form that has his name and email to an endpoint on the server I update his credentials using Firebase Admin SDK

// Handling User Profile Update
function settingsRouter(req, res) {
    // Validate User Information ...
    // Update User Info
    let displayName = req.body.fullName,
        email = req.body.email
    let userRecord = {
        email,
        displayName
    }
    return updateUser(res.locals.user.sub, userRecord).then(userRecord => {
        res.locals.user = userRecord;
        return res.render('dashboard/settings', {
            user: res.locals.user
        });
    }).catch(err => {
        return res.status(422).render('dashboard/settings', {
            user: res.locals.user
        });
    });
}

Now the view gets updated when the user submits the form because I set the res.locals.user variable to the new userRecord but once he refreshes the page the view shows the old credentials because before any get request for a protected content the middle ware isAuthenticated gets executed and the later gets user information from the session cookie which contains the old user credentials before he updated them.

So far these are the conclusions that I came to and what I tried to do:

• If I want the view to render properly I should sign out and sign in again to get a new Firebase ID token to create a new session cookie which is not an option.

• I tried to refresh the session cookie by creating a new ID token from the Admin SDK but it doesn't seem to have this option available and I can't do that through the client SDK because the user is already signed in.

• Storing the ID token to use later in creating session cookies is not an option as they expire after 1 hour.

I Googled the hell out of this problem before posting here so any help is so much appreciated.

Answer 1

I am facing a very similar scenario with one of my apps. I think the answer lies in these clues.

From Firebase docs

Firebase Auth provides server-side session cookie management for traditional websites that rely on session cookies. This solution has several advantages over client-side short-lived ID tokens, which may require a redirect mechanism each time to update the session cookie on expiration:

So they're hinting here that you want to manage the session and it's lifetime from the server.

Second clue is in the docs

Assuming an application is using httpOnly server side cookies, sign in a user on the login page using the client SDKs. A Firebase ID token is generated, and the ID token is then sent via HTTP POST to a session login endpoint where, using the Admin SDK, a session cookie is generated. On success, the state should be cleared from the client side storage.

If you look at the example code, the even explicitly set persistence to None to clear state from the client using firebase.auth().setPersistence(firebase.auth.Auth.Persistence.NONE);

So they are intending there to be no state on the client beyond the initial auth. They explicitly clear that state and expect an httponly cookie so the client can't grab the cookie (which really is just the ID token) and use it to get a new one.

It is odd that there is no clear way of refreshing the token client-side but there it is. You can only really create a session cookie with a super long lifetime and decide on the server when to delete the cookie or revoke the refresh token etc.

So that leaves the other option: manage state client-side. Some examples and tutorials simply send the ID token from the client to the server in a cookie. The satte sits on the client and the client can use the ID token to use all firebase features. The server can verify the user identity and use the token etc.

This scenario should work better. If the server needs to kick the user then it can delete the cookie revoke the refresh token (a bit harsh admittedly).

Hope that helps. Another scheme would be to build custom tokens, then you have complete control.