Better url detection

user-binding.php

@@ -23,5 +23,6 @@ $isTeacher = has_capability('mod/labnbook:addinstance', $context);
 $role = ($isTeacher ? 'teacher' : 'learner');
 global $USER;
 $url = $fetchInstitution->getRedirectUrl();
-$token=$fetchInstitution->getBindingTokenForRedirect($returnUrl, $role, $USER);
+$actual_link = (isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] === 'on' ? "https" : "http") . "://$_SERVER[HTTP_HOST]$returnUrl";
+$token=$fetchInstitution->getBindingTokenForRedirect($actual_link, $role, $USER);
 redirect($url."?token=".$token);