added functionality for Gumroad Redirect Script

admin/insert.php

@@ -8,6 +8,8 @@ if (!isset($_SESSION["login"]) && $_SESSION["login"] != "true-as-hell") {
 
 if (isset($_GET["url"])) {
     $presetedURL = $_GET["url"];
+} else if (isset($_POST["url"])) {
+    $presetedURL = $_POST["url"];
 } else {
     $presetedURL = "";
 }