passport-facebook-canvas

Facebook canvas authentication strategy for Passport.

npm install passport-facebook-canvas
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Passport Strategy for Facebook Canvas apps

Use this strategy to log users in to your Facebook Canvas app automatically.

Note: This strategy simply augments passport-facebook, if you don't need Facebook Canvas support you should use that module instead.

npm install passport-facebook-canvas --save

NPM

App Settings

Facebook Settings

Configuring Secure Canvas Url

Facebook has deprecated Canvas Url in favour of Secure Canvas Url and so requires setting up an SSL cert. You can produce a self-signed certificate with a command such as this: (don't set a password for a testing cert)

# Ubuntu
sudo openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout self_signed_ssl.key -out self_signed_ssl.crt

Then you must tell express to listen on another port, something like this:

var certificate = {
  key: fs.readFileSync(path.resolve(__dirname, './self_signed_ssl.key'), 'utf8'),
  cert: fs.readFileSync(path.resolve(__dirname, './self_signed_ssl.crt'), 'utf8')
}

http.createServer(app).listen(3000);
https.createServer(certificate, app).listen(3001);

Configure Strategy

Configuration is exactly the same as with passport-facebook except the module name is 'passport-facebook-canvas' instead of 'passport-facebook'.

var FacebookStrategy = require('passport-facebook-canvas');

passport.use(new FacebookStrategy({
    clientID: FACEBOOK_APP_ID,
    clientSecret: FACEBOOK_APP_SECRET,
    callbackURL: "http://localhost:3000/auth/facebook/callback"
  },
  function(accessToken, refreshToken, profile, done) {
    User.findOrCreate({ facebookId: profile.id }, function (err, user) {
      return done(err, user);
    });
  }
));

Authentication Routes

Configuration is exactly the same as with passport-facebook except the strategy name is 'facebook-canvas' instead of 'facebook'.

app.get('/auth/facebook', passport.authenticate('facebook-canvas'));

app.get('/auth/facebook/callback', 
  passport.authenticate('facebook-canvas', { successRedirect: '/',
                                             failureRedirect: '/error' }));

Canvas Route

This is the Secure Canvas Url route that Facebook will POST data to.

Note If this is the first time the app has seen this user then redirect to failureRedirect.

app.post('/auth/facebook/canvas', 
  passport.authenticate('facebook-canvas', { successRedirect: '/',
                                             failureRedirect: '/auth/facebook/canvas/autologin' }));

Auto Login Route

We cannot forward the user to another URL via HTTP redirect so we have to use a client-side js hack instead.

app.get('/auth/facebook/canvas/autologin', function( req, res ){
  res.send( '<!DOCTYPE html>' +
              '<body>' +
                '<script type="text/javascript">' +
                  'top.location.href = "/auth/facebook";' +
                '</script>' +
              '</body>' +
            '</html>' );
});

Please suggest a better solution: https://developers.facebook.com/docs/appsonfacebook/tutorial/#canvas

Done

Now you should be able to navigate to your app page: https://apps.facebook.com/myapp/ and be prompted to approve the app. On subsequent visits you should be logged in automatically.

License

(The MIT License)

Copyright (c) 2013 Peter Johnson <@insertcoffee>

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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