Your problem is caused by the lack of markers OpenGraph, as you say it is not possible that you implement for some reason.
For you, the only solution is to use the PHP Facebook API.
When creating the application you will have two key data for your code:
YOUR_APP_ID
YOUR_APP_SECRET
Download the Facebook PHP SDK from here.
You can start with this code for share content from your site:
<?php
// Remember to copy files from the SDK's src/ directory to a
// directory in your application on the server, such as php-sdk/
require_once('php-sdk/facebook.php');
$config = array(
'appId' => 'YOUR_APP_ID',
'secret' => 'YOUR_APP_SECRET',
'allowSignedRequest' => false // optional but should be set to false for non-canvas apps
);
$facebook = new Facebook($config);
$user_id = $facebook->getUser();
?>
<html>
<head></head>
<body>
<?php
if($user_id) {
// We have a user ID, so probably a logged in user.
// If not, we'll get an exception, which we handle below.
try {
$ret_obj = $facebook->api('/me/feed', 'POST',
array(
'link' => 'www.example.com',
'message' => 'Posting with the PHP SDK!'
));
echo '<pre>Post ID: ' . $ret_obj['id'] . '</pre>';
// Give the user a logout link
echo '<br /><a href="' . $facebook->getLogoutUrl() . '">logout</a>';
} catch(FacebookApiException $e) {
// If the user is logged out, you can have a
// user ID even though the access token is invalid.
// In this case, we'll get an exception, so we'll
// just ask the user to login again here.
$login_url = $facebook->getLoginUrl( array(
'scope' => 'publish_stream'
));
echo 'Please <a href="' . $login_url . '">login.</a>';
error_log($e->getType());
error_log($e->getMessage());
}
} else {
// No user, so print a link for the user to login
// To post to a user's wall, we need publish_stream permission
// We'll use the current URL as the redirect_uri, so we don't
// need to specify it here.
$login_url = $facebook->getLoginUrl( array( 'scope' => 'publish_stream' ) );
echo 'Please <a href="' . $login_url . '">login.</a>';
}
?>
</body>
</html>
You can find more examples in the Facebook Developers site: