first version of change_password interceptor (more see details)

- add stripLocalpart in helpers.php
- extend mxDatabase to update the password once validated

internal/intercept_change_password.php

@@ -0,0 +1,73 @@
+<?php
+/**
+ * Copyright 2018 Matthias Kesler
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// URL for this: /_matrix/client/r0/account/password?access_token=$ACCESS_TOKEN
+$response=[
+	"errcode" => "M_UNKNOWN",
+	"error" => "Unknown error while handling password changing",
+];
+header('Access-Control-Allow-Origin: *');
+header('Access-Control-Allow-Methods: POST, OPTIONS');
+header('Access-Control-Allow-Headers: Origin, X-Requested-With, Content-Type, Accept, Authorization');
+if ($_SERVER['REQUEST_METHOD'] === 'OPTIONS') {
+	$response = [];
+	// return with success
+	exit();
+}
+try {
+	$inputJSON = file_get_contents('php://input');
+	$input = json_decode($inputJSON, TRUE);
+	if (empty($input)) {
+		throw new Exception('no valid json as input present');
+	}
+	if (!isset($input["auth"])) {
+		throw new Exception('"auth" is not defined');
+	}
+	if (!isset($input["auth"]["user"]) || !isset($input["auth"]["password"])) {
+		throw new Exception('"auth.user" or "auth.password" is not defined');
+	}
+	if (!isset($input["auth"]["type"]) || $input["auth"]["type"] !== "m.login.password") {
+		throw new Exception('no or unknown auth.type');
+	}
+	if (!isset($input["new_password"])) {
+		throw new Exception('"new_password" is not defined');
+	}
+
+	require_once("../helpers.php");
+	$localpart = stripLocalpart($input["auth"]["user"]);
+
+	if (empty($localpart)) {
+		throw new Exception ("localpart cannot be identified");
+	}
+
+	require_once("../database.php");
+	if ($mx_db->updatePassword(
+		$localpart,
+		$input["auth"]["password"],
+		$input["new_password"]
+	)) {
+		$response=[];
+	} else {
+		throw new Exception("invalid credentials or another error while updating");
+	}
+
+} catch (Exception $e) {
+	header("HTTP/1.0 500 Internal Error");
+	error_log("failed with error: " . $e->getMessage());
+	$response["error"] = $e->getMessage();
+}
+print (json_encode($response, JSON_PRETTY_PRINT) . "\n");
+?>