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Monday, 17 December 2012

Facebook login integration with website, Login with Facebook for websites

Facebook provide OAuth support provides web developers are able to create a Login or Sign In option with Existing Facebook Account without spending more time on new registration on your website.
Herewith we saw how to integrate in to your website using  Login with Facebook Button in easy way.

In Order to Create a "Login with Facebook"for your website you need a Facebook account to generate APP_ID and APP_SECRET, Create a Facebook user account and Navigate to the App Developer Page
http://www.facebook.com/developers/

In Top right  press "Create New App" Button.
Read more


<?php
session_start();
define('YOUR_APP_ID', 'YOUR_APP_KEY_HERE');
define('YOUR_APP_SECRET', 'YOUR_SECRET_KEY_HERE');

function get_facebook_cookie($app_id, $app_secret) { 
    $signed_request = parse_signed_request(@$_COOKIE['fbsr_' . $app_id], $app_secret);
    // $signed_request should now have most of the old elements
    $signed_request['uid'] = $signed_request['user_id']; // for compatibility 
    if (!is_null($signed_request)) {
        // the cookie is valid/signed correctly
        // lets change "code" into an "access_token"
  // openssl must enable on your server inorder to access HTTPS
        $access_token_response = file_get_contents("https://graph.facebook.com/oauth/access_token?client_id=$app_id&redirect_uri=&client_secret=$app_secret&code={$signed_request['code']}");
        parse_str($access_token_response);
        $signed_request['access_token'] = $access_token;
        $signed_request['expires'] = time() + $expires;
    }
    return $signed_request;
}

function parse_signed_request($signed_request, $secret) {
  list($encoded_sig, $payload) = explode('.', $signed_request, 2); 

  // decode the data
  $sig = base64_url_decode($encoded_sig);
  $data = json_decode(base64_url_decode($payload), true);

  if (strtoupper($data['algorithm']) !== 'HMAC-SHA256') {
    error_log('Unknown algorithm. Expected HMAC-SHA256');
    return null;
  }

  // check sig
  $expected_sig = hash_hmac('sha256', $payload, $secret, $raw = true);
  if ($sig !== $expected_sig) {
    error_log('Bad Signed JSON signature!');
    return null;
  }

  return $data;
}

function base64_url_decode($input) {
  return base64_decode(strtr($input, '-_', '+/'));
}

if (isset($_COOKIE['fbsr_' . YOUR_APP_ID]))
{ 
$cookie = get_facebook_cookie(YOUR_APP_ID, YOUR_APP_SECRET);

$user = json_decode(@file_get_contents(
    'https://graph.facebook.com/me?access_token=' .
    $cookie['access_token']));
 
/*
Uncomment this to show all available variables
echo "<pre>";
 - print_r function expose all the values available to get from facebook login connect.
print_r($user);
 1. Save nessary values from $user Object to your Database
 2. Register a Sesion Variable based on your user account code
 3. Redirect to Account Dashboard
echo "</pre>";
*/
 
}
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Facebook Login Connect for Website Demo</title>
<style type="text/css">
body,td,th {
 font-family: Verdana, Geneva, sans-serif;
 font-size: 14px;
 color: #333;
}
body {
 margin-left: 50px;
 margin-top: 50px;
}
</style>
</head>
<body>
<?php if (@$cookie) { ?>
<h2>Welcome <?= $user->name ?> </h2> <br />
E-mail ID: <?= $user->email ?>
<br />
<a href="javascript://" onclick="FB.logout(function() { window.location='facebook-login.php' }); return false;" >Logout</a>
<?php } else { ?>
<h2>Welcome Guest! </h2>    
<div id="fb-root"></div>
<fb:login-button perms="email" width="width_value" show_faces="true" autologoutlink="true" size="large">Login with Facebook</fb:login-button>
<?php } ?>
<script src="http://connect.facebook.net/en_US/all.js"></script>   
<script>
 // Initiate FB Object
 FB.init({
   appId: '<?= YOUR_APP_ID ?>', 
   status: true,
   cookie: true, 
   xfbml: true
   });
 // Reloading after successfull login
 FB.Event.subscribe('auth.login', function(response) { 
 window.location.reload(); 
 });
</script>
</body>
</html>