From d68fec43390cda917837d788ecffbee4fc419929 Mon Sep 17 00:00:00 2001
From: steckbrief <steckbrief@chefmail.de>
Date: Mon, 4 Jan 2016 12:46:38 +0100
Subject: initial backend script implementation

---
 storage-backend/.htaccess |   3 +
 storage-backend/index.php | 139 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 142 insertions(+)
 create mode 100644 storage-backend/.htaccess
 create mode 100644 storage-backend/index.php

diff --git a/storage-backend/.htaccess b/storage-backend/.htaccess
new file mode 100644
index 0000000..6655c30
--- /dev/null
+++ b/storage-backend/.htaccess
@@ -0,0 +1,3 @@
+RewriteEngine on
+RewriteCond %{REQUEST_METHOD} =PUT
+RewriteRule ^(.*)$ index.php?uri=$1 [L,QSA]
diff --git a/storage-backend/index.php b/storage-backend/index.php
new file mode 100644
index 0000000..3a2668a
--- /dev/null
+++ b/storage-backend/index.php
@@ -0,0 +1,139 @@
+<?php
+/*
+ * This script serves as storing backend for the xmpp extension
+ * XEP-0313 Http Upload
+ */
+ 
+$method = $_SERVER['REQUEST_METHOD'];
+
+// Load configuration
+$config = require('config.php');
+
+switch ($method) {
+  case 'POST':
+    // parse post parameters
+    // check if all parameters are present - return 400 (bad request) if a parameter is missing / empty
+	$xmppServerKey = getMandatoryPostParameter('xmpp_server_key');
+	$filename = getMandatoryPostParameter('filename');
+	$filesize = getMandatoryPostParameter('size');
+	$type = getMandatoryPostParameter('content_type');
+	$userJid = getMandatoryPostParameter('user_jid');
+    // check file size - return 406 (not acceptable) if file too large
+    if ($filesize > $config['max_upload_file_size']) {
+      sendHttpErrorCodeAndMessage(406, 'File too large. Maximum file size: '.$config['max_upload_file_size']);
+	}
+    // check file name - return 406 (not acceptable) if file contains invalid characters
+    foreach ($config['invalid_characters_in_filename'] as $invalidCharacter) {
+      if (stripos($filename, $invalidCharacter) !== false) {
+        sendHttpErrorCodeAndMessage(406, 'Invalid character found in filename.');
+      }
+    }
+    // generate slot uuid, register slot uuid and expected file size and expected mime type
+    $basePath = $config['storage_base_path'];
+    $slotUUID = generate_uuid();
+    registerSlot($slotUUID, $filename, $filesize, $type, $userJid, $config);
+    if (!mkdir(getUploadFilePath($slotUUID, $config))) {
+      sendHttpErrorCodeAndMessage(500, "Could not create directory for upload.");
+    }
+    // return 200 for success and get / put url Json formatted ( ['get'=>url, 'put'=>url] )
+    $result = array('put' => $config['base_url_put'].$slotUUID.'/'.$filename,
+                    'get' => $config['base_url_get'].$slotUUID.'/'.$filename);
+    echo json_encode($result);
+    break;
+  case 'PUT':
+    // check slot uuid - return 403 if not existing
+    $uri = $_SERVER["REQUEST_URI"];
+    $slotUUID = getUUIDFromUri($uri);
+    $filename = getFilenameFromUri($uri);
+    $uploadFilePath = getUploadFilePath($slotUUID, $config, $filename);
+    if (file_exists($uploadFilePath)) {
+      sendHttpErrorCodeAndMessage(403, "The slot was already used.");
+    }
+    if (!slotExists($slotUUID, $config)) {
+      sendHttpErrorCodeAndMessage(403, "The slot does not exist.");
+    }
+    $slotParameters = require(getSlotFilePath($slotUUID, $config));
+    // save file
+    $incomingFileStream = fopen("php://input", "r");
+    $targetFileStream = fopen($uploadFilePath, "w");
+    $uploadedFilesize = stream_copy_to_stream($incomingFileStream, $targetFileStream);
+    fclose($targetFileStream);
+    // check actual file size with registered file size - return 413
+    if ($uploadedFilesize != $slotParameters['filesize']) {
+      unlink($uploadedFilePath);
+      sendHttpErrorCodeAndMessage(403, "Uploaded file size differs from requestes slot size.");
+    }
+    // check actual mime type with registered mime type
+    if (mime_content_type($uploadFilePath) != $slotParameters['content_type']) {
+      unlink($uploadedFilePath);
+      sendHttpErrorCodeAndMessage(403, "Uploaded file content type differs from requestes slot content type.");
+    }
+    // return 500 in case of any error
+    // return 201 for success
+    sendHttpErrorCodeAndMessage(201);
+    break;
+  case 'GET': // better use really apache to serve files...
+    break;
+}
+
+function getMandatoryPostParameter($parameterName) {
+  $parameter = $_POST[$parameterName];
+  if (!isset($parameter) || is_null($parameter) || empty($parameter)) {
+    sendHttpErrorCodeAndMessage(400, 'Missing parameter "'.$parameterName.'"');
+  }
+  return $parameter;
+}
+
+function sendHttpErrorCodeAndMessage($code, $text = '') {
+  http_response_code($code);
+  exit($text);
+}
+
+function getUUIDFromUri($uri) {
+  $pattern = "/[a-f0-9]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}/";
+  preg_match($pattern, $uri, $matches);
+  return $matches[0];
+}
+
+function getFilenameFromUri($uri) {
+  $lastSlash = strrpos($uri, '/');
+  return substr($uri, $lastSlash);
+}
+
+function registerSlot($slotUUID, $filename, $filesize, $contentType, $userJid, $config) {
+  $contents = "<?php\n/*\n * This is an autogenerated file - do not edit\n */\n\n";
+  $contents .= 'return array(\'filename\' => \''.$filename.'\', \'filesize\' => \''.$filesize.'\', ';
+  $contents .= '\'content_type\' => \''.$contentType.'\', \'user_jid\' => \''.$userJid.'\');';
+  if (!file_put_contents(getSlotFilePath($slotUUID, $config), $contents)) {
+    sendHttpErrorCodeAndMessage(500, "Could not create slot registry entry.");
+  }
+}
+
+function slotExists($slotUUID, $config) {
+  return file_exists(getSlotFilePath($slotUUID, $config));
+}
+
+function getSlotFilePath($slotUUID, $config) {
+  return $config['slot_registry_dir'].$slotUUID;
+}
+
+function getUploadFilePath($slotUUID, $config, $filename = NULL) {
+  $path = $config['storage_base_path'].$slotUUID;
+  if (!is_null($filename)) {
+    $path .= '/'.$filename;
+  }
+  return $path;
+}
+
+/**
+ * Copied from http://rogerstringer.com/2013/11/15/generate-uuids-php/
+ */ 
+function generate_uuid() {
+  return sprintf( '%04x%04x-%04x-%04x-%04x-%04x%04x%04x',
+    mt_rand( 0, 0xffff ), mt_rand( 0, 0xffff ),
+    mt_rand( 0, 0xffff ),
+    mt_rand( 0, 0x0fff ) | 0x4000,
+    mt_rand( 0, 0x3fff ) | 0x8000,
+    mt_rand( 0, 0xffff ), mt_rand( 0, 0xffff ), mt_rand( 0, 0xffff )
+  );
+}
-- 
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