How to provide frontend with JSON web token after server authentication? - node.js

Question

So far I have only dealt with server-rendered apps, where after a user logs in via username/password or using an OAuth provider (Facebook etc.), the server just sets a session cookie while redirecting to the relevant page.
However now I'm attempting to build an app using a more 'modern' approach, with React on the frontend and a JSON API backend. Apparently the standard choice for this is to use a JSON web token for authentication, however I'm having trouble working out how I'm meant to provide the JWT to the client so it can be stored in session/local storage or wherever.
Example to illustrate better:
User clicks link (/auth/facebook) to log in via Facebook
User is redirected and shown Facebook login form and/or permission dialog (if necessary)
Facebook redirects user back to /auth/facebook/callback with an authorization code in tow, the server exchanges this for an access token and some information about the user
Server finds or creates the user in the DB using the info, then creates a JWT containing a relevant subset of the user data (e.g. ID)
???
At this point I just want the user to be redirected to the main page for the React app (let's say /app) with the JWT in tow, so the frontend can take over. But I can't think of an (elegant) way to do that without losing the JWT along the way, other than to put it in the query string for the redirect (/app?authtoken=...) - but that will display in the address bar until I remove it manually using replaceState() or whatever, and seems a little weird to me.
Really I'm just wondering how this is typically done, and I'm almost sure I'm missing something here. The server is Node (Koa with Passport), if that helps.
Edit: To be clear, I'm asking what the best way is to provide a token to the client (so it can be saved) after an OAuth redirect flow using Passport.

Answer 1

I recently ran across this same issue, and, not finding a solution here or elsewhere, wrote this blog post with my in-depth thoughts.
TL;DR: I came up with 3 possible approaches to send the JWT to the client after OAuth logins/redirects:
Save the JWT in a cookie, then extract it on the front-end or server in a future step (eg. extract it on the client with JS, or send a request to the server, server uses the cookie to get the JWT, returns the JWT).
Send the JWT back as part of the query string (which you suggest in your question).
Send back a server-rendered HTML page with a <script> tag that:
Automatically saves the embedded JWT to localStorage
Automatically redirects the client to whatever page you like after that.
(Since logging in with JWTs is essentially equivalent to "saving the JWT to localStorage, my favorite option was #3, but it's possible there are downsides I haven't considered. I'm interested in hearing what others think here.)
Hope that helps!

Answer 2

Client: Open a popup window via $auth.authenticate('provider name').
Client: Sign in with that provider, if necessary, then authorize the application.
Client: After successful authorization, the popup is redirected back to your app, e.g. http://localhost:3000, with the code (authorization code) query string parameter.
Client: The code parameter is sent back to the parent window that opened the popup.
Client: Parent window closes the popup and sends a POST request to /auth/provider withcode parameter.
Server: Authorization code is exchanged for access token.
Server: User information is retrived using the access token from Step 6.
Server: Look up the user by their unique Provider ID. If user already exists, grab the existing user, otherwise create a new user account.
Server: In both cases of Step 8, create a JSON Web Token and send it back to the client.
Client: Parse the token and save it to Local Storage for subsequent use after page reload.
Log out
Client: Remove token from Local Storage

Answer 3

here is a login request from the server side. it's storing the token in the header:
router.post('/api/users/login', function (req, res) {
var body = _.pick(req.body, 'username', 'password');
var userInfo;
models.User.authenticate(body).then(function (user) {
var token = user.generateToken('authentication');
userInfo = user;
return models.Token.create({
token: token
});
}).then(function (tokenInstance) {
res.header('Auth', tokenInstance.get('token')).json(userInfo.toPublicJSON());
}).catch(function () {
res.status(401).send();
});
});
here is the login request on the react side, where I am grabbing the token from the header and setting the token in local storage once the username and password pass authentication:
handleNewData (creds) {
const { authenticated } = this.state;
const loginUser = {
username: creds.username,
password: creds.password
}
fetch('/api/users/login', {
method: 'post',
body: JSON.stringify(loginUser),
headers: {
'Authorization': 'Basic'+btoa('username:password'),
'content-type': 'application/json',
'accept': 'application/json'
},
credentials: 'include'
}).then((response) => {
if (response.statusText === "OK"){
localStorage.setItem('token', response.headers.get('Auth'));
browserHistory.push('route');
response.json();
} else {
alert ('Incorrect Login Credentials');
}
})
}

Answer 4

When you get a token from any passport authentication sites you have to save the token in your browser's localStorage. The Dispatch is Redux's Middleware. Ignore dispatch if you don't use redux in your app. you can just use setState here (A bit weird without redux).
Client-side:
Here's something similar API of mine, which returns token.
saving tokens
axios.post(`${ROOT_URL}/api/signin`, { email, password })
.then(response => {
dispatch({ type: AUTH_USER }); //setting state (Redux's Style)
localStorage.setItem('token', response.data.token); //saving token
browserHistory.push('/home'); //pushes back the user after storing token
})
.catch(error => {
var ERROR_DATA;
try{
ERROR_DATA = JSON.parse(error.response.request.response).error;
}
catch(error) {
ERROR_DATA = 'SOMETHING WENT WRONG';
}
dispatch(authError(ERROR_DATA)); //throw error (Redux's Style)
});
So When you make some authenticated requests,you have to attach the token with the request in this form.
authenticated requests
axios.get(`${ROOT_URL}/api/blog/${blogId}`, {
headers: { authorization: localStorage.getItem('token') }
//take the token from localStorage and put it on headers ('authorization is my own header')
})
.then(response => {
dispatch({
type: FETCH_BLOG,
payload: response.data
});
})
.catch(error => {
console.log(error);
});
Here's my index.js:
The token is checked each and everytime, so even if the browser got refreshed, you can still set the state.
checks if the user is authenticated
const token = localStorage.getItem('token');
if (token) {
store.dispatch({ type: AUTH_USER })
}
ReactDOM.render(
<Provider store={store}>
<Router history={browserHistory}>
<Route path="/" component={App}>
..
..
..
<Route path="/blog/:blogid" component={RequireAuth(Blog)} />
//ignore this requireAuth - that's another component, checks if a user is authenticated. if not pushes to the index route
</Route>
</Router>
</Provider>
, document.querySelector('.container'));
All that dispach actions does is it sets the state.
my reducer file(Redux only) else you can just use setState() in your index route file to provide the state to the whole application. Every time the dispatch is called, it runs a similar reducer file like this which sets the state.
setting the state
import { AUTH_USER, UNAUTH_USER, AUTH_ERROR } from '../actions/types';
export default function(state = {}, action) {
switch(action.type) {
case AUTH_USER:
return { ...state, error: '', authenticated: true };
case UNAUTH_USER:
return { ...state, error: '', authenticated: false };
case AUTH_ERROR:
return { ...state, error: action.payload };
}
return state;
} //you can skip this and use setState() in your index route instead
Delete the token from your localStorage to logout.
caution: Use any different name rather than token to save the token in your browser's localStorage
Server-Side:
considering your passport services file. You must set the header search.
Here's passport.js
const passport = require('passport');
const ExtractJwt = require('passport-jwt').ExtractJwt;
const JwtStrategy = require('passport-jwt').Strategy;
..
..
..
..
const jwtOptions = {
jwtFromRequest: ExtractJwt.fromHeader('authorization'), //client's side must specify this header
secretOrKey: config.secret
};
const JWTVerify = new JwtStrategy(jwtOptions, (payload, done) => {
User.findById(payload._id, (err, user) => {
if (err) { done(err, null); }
if (user) {
done(null, user);
} else {
done(null, false);
}
});
});
passport.use(JWTVerify);
In my router.js
const passportService = require('./services/passport');
const requireAuthentication = passport.authenticate('jwt', { session: false });
..
..
..
//for example the api router the above react action used
app.get('/api/blog/:blogId', requireAuthentication, BlogController.getBlog);