FOSOAuthServerBundle - generate manually an access token - ios

Question

I have a symfony2 website and a web service secured via oauth using FOSOAuthServerBundle accessible via an iOS app. On the website I use FOSUserBundle and FOSFacebookBundle.
The only thing I miss is giving the possibility to the user to login with facebook on the iOS app and to return him an access_token for my oauth linked to his user account so that he can access my api like other users.
So basically I want to send the user facebookID and facebook_access_token to my webservice, check that the user is correct (token matches my app) and return an authentication token.
QUESTION: is there an easy way to add a "Facebook" grant_type to FOSOAuthServerBundle ?
I know some people have done this seeing these questions:
Design for Facebook authentication in an iOS app that also accesses a secured web service
Get application id from user access token (or verify the source application for a token)
But they do not explain how, they do not seem to use FOSOauthServerBundle and questions are quite old.
I have tried using this bundle:
https://github.com/TheFootballSocialClub/FSCOAuth2FacebookGrantBundle
but this bundle has been downloaded only 9 times before me and is not fully suited to my app (it considers that a Facebook user username equals his facebookId for instance). So I guess what I want to do is re-implement the same kind of thing my own way.
If anyone has already done that our could provide any guidance it would be very much appreciated.
Thank you

Answer 1

To do this, you have to add a Grant Extensions, see the official document "Adding Grant Extensions" : https://github.com/FriendsOfSymfony/FOSOAuthServerBundle/blob/master/Resources/doc/adding_grant_extensions.md
You can find my FacebookGrantExtension to get a token from a FB access_token :
class FacebookGrantExtension implements GrantExtensionInterface
{
protected $userManager = null;
protected $facebookSdk = null;
public function __construct(UserManager $userManager, \BaseFacebook $facebookSdk)
{
$this->userManager = $userManager;
$this->facebookSdk = $facebookSdk;
}
/**
* #see OAuth2\IOAuth2GrantExtension::checkGrantExtension
*/
public function checkGrantExtension(IOAuth2Client $client, array $inputData, array $authHeaders)
{
if (!isset($inputData['facebook_access_token'])) {
return false;
}
$this->facebookSdk->setAccessToken($inputData['facebook_access_token']);
try {
// Try to get the user with the facebook token from Open Graph
$fbData = $this->facebookSdk->api('/me');
if (empty($fbData) || !isset($fbData['id'])) {
return false;
}
// Check if a user match in database with the facebook id
$user = $this->userManager->findUserBy(array(
'facebookId' => $fbData['id']
));
// If no user found, register a new user and grant token
if (null === $user) {
return false;
}
// Else, return the access_token for the user
else {
return array(
'data' => $user
);
}
} catch(\FacebookApiExceptionion $e) {
return false;
}
}
}
And the config.yml :
my.oauth.facebook_extension:
class: My\CoreBundle\Oauth\FacebookGrantExtension
arguments:
userManager: "#fos_user.user_manager"
facebookSdk: "#fos_facebook.api"
tags:
- { name: fos_oauth_server.grant_extension, uri: 'http://grants.api.mywebsite.com/facebook_access_token' }