--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/program/lib/Roundcube/rcube_base_replacer.php	Thu Jan 04 15:52:31 2018 -0500
@@ -0,0 +1,123 @@
+<?php
+
+/**
+ +-----------------------------------------------------------------------+
+ | This file is part of the Roundcube Webmail client                     |
+ | Copyright (C) 2005-2012, The Roundcube Dev Team                       |
+ |                                                                       |
+ | Licensed under the GNU General Public License version 3 or            |
+ | any later version with exceptions for skins & plugins.                |
+ | See the README file for a full license statement.                     |
+ |                                                                       |
+ | PURPOSE:                                                              |
+ |   Provide basic functions for base URL replacement                    |
+ +-----------------------------------------------------------------------+
+ | Author: Thomas Bruederli <roundcube@gmail.com>                        |
+ +-----------------------------------------------------------------------+
+*/
+
+/**
+ * Helper class to turn relative urls into absolute ones
+ * using a predefined base
+ *
+ * @package    Framework
+ * @subpackage Utils
+ * @author     Thomas Bruederli <roundcube@gmail.com>
+ */
+class rcube_base_replacer
+{
+    private $base_url;
+
+
+    /**
+     * Class constructor
+     *
+     * @param string $base Base URL
+     */
+    public function __construct($base)
+    {
+        $this->base_url = $base;
+    }
+
+    /**
+     * Replace callback
+     *
+     * @param array $matches Matching entries
+     *
+     * @return string Replaced text with absolute URL
+     */
+    public function callback($matches)
+    {
+        return $matches[1] . '="' . self::absolute_url($matches[3], $this->base_url) . '"';
+    }
+
+    /**
+     * Convert base URLs to absolute ones
+     *
+     * @param string $body Text body
+     *
+     * @return string Replaced text
+     */
+    public function replace($body)
+    {
+        $regexp = array(
+            '/(src|background|href)=(["\']?)([^"\'\s>]+)(\2|\s|>)/i',
+            '/(url\s*\()(["\']?)([^"\'\)\s]+)(\2)\)/i',
+        );
+
+        return preg_replace_callback($regexp, array($this, 'callback'), $body);
+    }
+
+    /**
+     * Convert paths like ../xxx to an absolute path using a base url
+     *
+     * @param string $path     Relative path
+     * @param string $base_url Base URL
+     *
+     * @return string Absolute URL
+     */
+    public static function absolute_url($path, $base_url)
+    {
+        // check if path is an absolute URL
+        if (preg_match('/^[fhtps]+:\/\//', $path)) {
+            return $path;
+        }
+
+        // check if path is a content-id scheme
+        if (strpos($path, 'cid:') === 0) {
+            return $path;
+        }
+
+        $host_url = $base_url;
+        $abs_path = $path;
+
+        // cut base_url to the last directory
+        if (strrpos($base_url, '/') > 7) {
+            $host_url = substr($base_url, 0, strpos($base_url, '/', 7));
+            $base_url = substr($base_url, 0, strrpos($base_url, '/'));
+        }
+
+        // $path is absolute
+        if ($path[0] == '/') {
+            $abs_path = $host_url.$path;
+        }
+        else {
+            // strip './' because its the same as ''
+            $path = preg_replace('/^\.\//', '', $path);
+
+            if (preg_match_all('/\.\.\//', $path, $matches, PREG_SET_ORDER)) {
+                $cnt = count($matches);
+                while ($cnt--) {
+                    if ($pos = strrpos($base_url, '/')) {
+                        $base_url = substr($base_url, 0, $pos);
+                    }
+                    $path = substr($path, 3);
+                }
+            }
+
+            $abs_path = $base_url.'/'.$path;
+        }
+
+        return $abs_path;
+    }
+}