Add validateuser.php ajax file returning json data saying whether a user...

Add validateuser.php ajax file returning json data saying whether a user exists and the credentials are correct

core/ajax/validateuser.php

+<?php
+
+/**
+* ownCloud
+*
+* @author Hans Bakker
+* @copyright 2011 Hans Bakker hansmbakker+kde@gmail.com
+*
+* This library is free software; you can redistribute it and/or
+* modify it under the terms of the GNU AFFERO GENERAL PUBLIC LICENSE
+* License as published by the Free Software Foundation; either
+* version 3 of the License, or any later version.
+*
+* This library is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+* GNU AFFERO GENERAL PUBLIC LICENSE for more details.
+*
+* You should have received a copy of the GNU Affero General Public
+* License along with this library.  If not, see <http://www.gnu.org/licenses/>.
+*
+*/
+
+header("Content-Type: application/jsonrequest");
+
+$RUNTIME_NOAPPS = TRUE; //no apps, yet
+
+require_once('../../lib/base.php');
+
+$not_installed = !OC_Config::getValue('installed', false);
+
+// First step : check if the server is correctly configured for ownCloud :
+$errors = OC_Util::checkServer();
+if(count($errors) > 0) {
+        echo json_encode(array("user_valid" => "false", "comment" => $errors));
+}
+
+// Setup required :
+elseif($not_installed) {
+        echo json_encode(array("user_valid" => "false", "comment" => "not_installed"));
+
+}
+
+// Someone wants to check a user:
+elseif(isset($_GET["user"]) and isset($_GET["password"])) {
+        if(OC_User::checkPassword($_GET["user"], $_GET["password"]))
+		echo json_encode(array("user_valid" => "true", "comment" => ""));
+	else
+		echo json_encode(array("user_valid" => "false", "comment" => ""));
+}
+
+// For all others cases:
+else {
+        echo json_encode(array("user_valid" => "false", "comment" => "unknown"));
+}
+
+?>