passport-facebook-canvas

Facebook canvas authentication strategy for Passport.

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 Canvas support you should use that instead.

App Settings

Configuring Secure Canvas Url

As far as I know, 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);

Configuring Routes

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', { successRedirect: '/',
                                      failureRedirect: '/auth/facebook/canvas/autologin' }));

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( reqres ){
  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


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.