Proyectos de Subversion Moodle

<?php

/**

 +-----------------------------------------------------------------------+

 | This file is part of the Roundcube Webmail client                     |

 |                                                                       |

 | Copyright (C) The Roundcube Dev Team                                  |

 | Copyright (C) Kolab Systems AG                                        |

 |                                                                       |

 | 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:                                                              |

 |   Utility class providing common functions                            |

 +-----------------------------------------------------------------------+

 | Author: Thomas Bruederli <roundcube@gmail.com>                        |

 | Author: Aleksander Machniak <alec@alec.pl>                            |

 +-----------------------------------------------------------------------+

*/

/**

 * Utility class providing common functions

 *

 * @package    Framework

 * @subpackage Utils

 */

class rcube_utils

{

    // define constants for input reading

    const INPUT_GET    = 1;

    const INPUT_POST   = 2;

    const INPUT_COOKIE = 4;

    const INPUT_GP     = 3; // GET + POST

    const INPUT_GPC    = 7; // GET + POST + COOKIE

    /**

     * A wrapper for PHP's explode() that does not throw a warning

     * when the separator does not exist in the string

     *

     * @param string $separator Separator string

     * @param string $string    The string to explode

     *

     * @return array Exploded string. Still an array if there's no separator in the string

     */

    public static function explode($separator, $string)

    {

        if (strpos($string, $separator) !== false) {

            return explode($separator, $string);

        }

        return [$string, null];

    }

    /**

     * Helper method to set a cookie with the current path and host settings

     *

     * @param string $name      Cookie name

     * @param string $value     Cookie value

     * @param int    $exp       Expiration time

     * @param bool   $http_only HTTP Only

     */

    public static function setcookie($name, $value, $exp = 0, $http_only = true)

    {

        if (headers_sent()) {

            return;

        }

        $attrib             = session_get_cookie_params();

        $attrib['expires']  = $exp;

        $attrib['secure']   = $attrib['secure'] || self::https_check();

        $attrib['httponly'] = $http_only;

        // session_get_cookie_params() return includes 'lifetime' but setcookie() does not use it, instead it uses 'expires'

        unset($attrib['lifetime']);

        setcookie($name, $value, $attrib);

    }

    /**

     * E-mail address validation.

     *

     * @param string $email     Email address

     * @param bool   $dns_check True to check dns

     *

     * @return bool True on success, False if address is invalid

     */

    public static function check_email($email, $dns_check = true)

    {

        // Check for invalid (control) characters

        if (preg_match('/\p{Cc}/u', $email)) {

            return false;

        }

        // Check for length limit specified by RFC 5321 (#1486453)

        if (strlen($email) > 254) {

            return false;

        }

        $pos = strrpos($email, '@');

        if (!$pos) {

            return false;

        }

        $domain_part = substr($email, $pos + 1);

        $local_part  = substr($email, 0, $pos);

        // quoted-string, make sure all backslashes and quotes are

        // escaped

        if (substr($local_part, 0, 1) == '"') {

            $local_quoted = preg_replace('/\\\\(\\\\|\")/','', substr($local_part, 1, -1));

            if (preg_match('/\\\\|"/', $local_quoted)) {

                return false;

            }

        }

        // dot-atom portion, make sure there's no prohibited characters

        else if (preg_match('/(^\.|\.\.|\.$)/', $local_part)

            || preg_match('/[\\ ",:;<>@]/', $local_part)

        ) {

            return false;

        }

        // Validate domain part

        if (preg_match('/^\[((IPv6:[0-9a-f:.]+)|([0-9.]+))\]$/i', $domain_part, $matches)) {

            return self::check_ip(preg_replace('/^IPv6:/i', '', $matches[1])); // valid IPv4 or IPv6 address

        }

        else {

            // If not an IP address

            $domain_array = explode('.', $domain_part);

            // Not enough parts to be a valid domain

            if (count($domain_array) < 2) {

                return false;

            }

            foreach ($domain_array as $part) {

                if (!preg_match('/^((xn--)?([A-Za-z0-9][A-Za-z0-9-]{0,61}[A-Za-z0-9])|([A-Za-z0-9]))$/', $part)) {

                    return false;

                }

            }

            // last domain part (allow extended TLD)

            $last_part = array_pop($domain_array);

            if (strpos($last_part, 'xn--') !== 0

                && (preg_match('/[^a-zA-Z0-9]/', $last_part) || preg_match('/^[0-9]+$/', $last_part))

            ) {

                return false;

            }

            $rcube = rcube::get_instance();

            if (!$dns_check || !function_exists('checkdnsrr') || !$rcube->config->get('email_dns_check')) {

                return true;

            }

            // Check DNS record(s)

            // Note: We can't use ANY (#6581)

            foreach (['A', 'MX', 'CNAME', 'AAAA'] as $type) {

                if (checkdnsrr($domain_part, $type)) {

                    return true;

                }

            }

        }

        return false;

    }

    /**

     * Validates IPv4 or IPv6 address

     *

     * @param string $ip IP address in v4 or v6 format

     *

     * @return bool True if the address is valid

     */

    public static function check_ip($ip)

    {

        return filter_var($ip, FILTER_VALIDATE_IP) !== false;

    }

    /**

     * Replacing specials characters to a specific encoding type

     *

     * @param string $str      Input string

     * @param string $enctype  Encoding type: text|html|xml|js|url

     * @param string $mode     Replace mode for tags: show|remove|strict

     * @param bool   $newlines Convert newlines

     *

     * @return string The quoted string

     */

    public static function rep_specialchars_output($str, $enctype = '', $mode = '', $newlines = true)

    {

        static $html_encode_arr = false;

        static $js_rep_table    = false;

        static $xml_rep_table   = false;

        if (!is_string($str)) {

            $str = strval($str);

        }

        // encode for HTML output

        if ($enctype == 'html') {

            if (!$html_encode_arr) {

                $html_encode_arr = get_html_translation_table(HTML_SPECIALCHARS);

                unset($html_encode_arr['?']);

            }

            $encode_arr = $html_encode_arr;

            if ($mode == 'remove') {

                $str = strip_tags($str);

            }

            else if ($mode != 'strict') {

                // don't replace quotes and html tags

                $ltpos = strpos($str, '<');

                if ($ltpos !== false && strpos($str, '>', $ltpos) !== false) {

                    unset($encode_arr['"']);

                    unset($encode_arr['<']);

                    unset($encode_arr['>']);

                    unset($encode_arr['&']);

                }

            }

            $out = strtr($str, $encode_arr);

            return $newlines ? nl2br($out) : $out;

        }

        // if the replace tables for XML and JS are not yet defined

        if ($js_rep_table === false) {

            $js_rep_table = $xml_rep_table = [];

            $xml_rep_table['&'] = '&';

            // can be increased to support more charsets

            for ($c=160; $c<256; $c++) {

                $xml_rep_table[chr($c)] = "&#$c;";

            }

            $xml_rep_table['"'] = '"';

            $js_rep_table['"']  = '\\"';

            $js_rep_table["'"]  = "\\'";

            $js_rep_table["\\"] = "\\\\";

            // Unicode line and paragraph separators (#1486310)

            $js_rep_table[chr(hexdec('E2')).chr(hexdec('80')).chr(hexdec('A8'))] = '
';

            $js_rep_table[chr(hexdec('E2')).chr(hexdec('80')).chr(hexdec('A9'))] = '
';

        }

        // encode for javascript use

        if ($enctype == 'js') {

            return preg_replace(["/\r?\n/", "/\r/", '/<\\//'], ['\n', '\n', '<\\/'], strtr($str, $js_rep_table));

        }

        // encode for plaintext

        if ($enctype == 'text') {

            return str_replace("\r\n", "\n", $mode == 'remove' ? strip_tags($str) : $str);

        }

        if ($enctype == 'url') {

            return rawurlencode($str);

        }

        // encode for XML

        if ($enctype == 'xml') {

            return strtr($str, $xml_rep_table);

        }

        // no encoding given -> return original string

        return $str;

    }

    /**

     * Read input value and make sure it is a string.

     *

     * @param string $fname      Field name to read

     * @param int    $source     Source to get value from (see self::INPUT_*)

     * @param bool   $allow_html Allow HTML tags in field value

     * @param string $charset    Charset to convert into

     *

     * @return string Request parameter value

     * @see self::get_input_value()

     */

    public static function get_input_string($fname, $source, $allow_html = false, $charset = null)

    {

        $value = self::get_input_value($fname, $source, $allow_html, $charset);

        return is_string($value) ? $value : '';

    }

    /**

     * Read request parameter value and convert it for internal use

     * Performs stripslashes() and charset conversion if necessary

     *

     * @param string $fname      Field name to read

     * @param int    $source     Source to get value from (see self::INPUT_*)

     * @param bool   $allow_html Allow HTML tags in field value

     * @param string $charset    Charset to convert into

     *

     * @return string|array|null Request parameter value or NULL if not set

     */

    public static function get_input_value($fname, $source, $allow_html = false, $charset = null)

    {

        $value = null;

        if (($source & self::INPUT_GET) && isset($_GET[$fname])) {

            $value = $_GET[$fname];

        }

        if (($source & self::INPUT_POST) && isset($_POST[$fname])) {

            $value = $_POST[$fname];

        }

        if (($source & self::INPUT_COOKIE) && isset($_COOKIE[$fname])) {

            $value = $_COOKIE[$fname];

        }

        return self::parse_input_value($value, $allow_html, $charset);

    }

    /**

     * Parse/validate input value. See self::get_input_value()

     * Performs stripslashes() and charset conversion if necessary

     *

     * @param string $value      Input value

     * @param bool   $allow_html Allow HTML tags in field value

     * @param string $charset    Charset to convert into

     *

     * @return string Parsed value

     */

    public static function parse_input_value($value, $allow_html = false, $charset = null)

    {

        if (empty($value)) {

            return $value;

        }

        if (is_array($value)) {

            foreach ($value as $idx => $val) {

                $value[$idx] = self::parse_input_value($val, $allow_html, $charset);

            }

            return $value;

        }

        // remove HTML tags if not allowed

        if (!$allow_html) {

            $value = strip_tags($value);

        }

        $rcube          = rcube::get_instance();

        $output_charset = is_object($rcube->output) ? $rcube->output->get_charset() : null;

        // remove invalid characters (#1488124)

        if ($output_charset == 'UTF-8') {

            $value = rcube_charset::clean($value);

        }

        // convert to internal charset

        if ($charset && $output_charset) {

            $value = rcube_charset::convert($value, $output_charset, $charset);

        }

        return $value;

    }

    /**

     * Convert array of request parameters (prefixed with _)

     * to a regular array with non-prefixed keys.

     *

     * @param int    $mode       Source to get value from (GPC)

     * @param string $ignore     PCRE expression to skip parameters by name

     * @param bool   $allow_html Allow HTML tags in field value

     *

     * @return array Hash array with all request parameters

     */

    public static function request2param($mode = null, $ignore = 'task|action', $allow_html = false)

    {

        $out = [];

        $src = $mode == self::INPUT_GET ? $_GET : ($mode == self::INPUT_POST ? $_POST : $_REQUEST);

        foreach (array_keys($src) as $key) {

            $fname = $key[0] == '_' ? substr($key, 1) : $key;

            if ($ignore && !preg_match('/^(' . $ignore . ')$/', $fname)) {

                $out[$fname] = self::get_input_value($key, $mode, $allow_html);

            }

        }

        return $out;

    }

    /**

     * Convert the given string into a valid HTML identifier

     * Same functionality as done in app.js with rcube_webmail.html_identifier()

     *

     * @param string $str    String input

     * @param bool   $encode Use base64 encoding

     *

     * @return string Valid HTML identifier

     */

    public static function html_identifier($str, $encode = false)

    {

        if ($encode) {

            return rtrim(strtr(base64_encode($str), '+/', '-_'), '=');

        }

        return asciiwords($str, true, '_');

    }

    /**

     * Replace all css definitions with #container [def]

     * and remove css-inlined scripting, make position style safe

     *

     * @param string $source       CSS source code

     * @param string $container_id Container ID to use as prefix

     * @param bool   $allow_remote Allow remote content

     * @param string $prefix       Prefix to be added to id/class identifier

     *

     * @return string Modified CSS source

     */

    public static function mod_css_styles($source, $container_id, $allow_remote = false, $prefix = '')

    {

        $last_pos     = 0;

        $replacements = new rcube_string_replacer;

        // ignore the whole block if evil styles are detected

        $source   = self::xss_entity_decode($source);

        $stripped = preg_replace('/[^a-z\(:;]/i', '', $source);

        $evilexpr = 'expression|behavior|javascript:|import[^a]' . (!$allow_remote ? '|url\((?!data:image)' : '');

        if (preg_match("/$evilexpr/i", $stripped)) {

            return '/* evil! */';

        }

        $strict_url_regexp = '!url\s*\(\s*["\']?(https?:)//[a-z0-9/._+-]+["\']?\s*\)!Uims';

        // remove html comments

        $source = preg_replace('/(^\s*<\!--)|(-->\s*$)/m', '', $source);

        // cut out all contents between { and }

        while (($pos = strpos($source, '{', $last_pos)) && ($pos2 = strpos($source, '}', $pos))) {

            $nested = strpos($source, '{', $pos+1);

            if ($nested && $nested < $pos2) { // when dealing with nested blocks (e.g. @media), take the inner one

                $pos = $nested;

            }

            $length = $pos2 - $pos - 1;

            $styles = substr($source, $pos+1, $length);

            $output = '';

            // check every css rule in the style block...

            foreach (self::parse_css_block($styles) as $rule) {

                // Remove 'page' attributes (#7604)

                if ($rule[0] == 'page') {

                    continue;

                }

                // Convert position:fixed to position:absolute (#5264)

                if ($rule[0] == 'position' && strcasecmp($rule[1], 'fixed') === 0) {

                    $rule[1] = 'absolute';

                }

                else if ($allow_remote) {

                    $stripped = preg_replace('/[^a-z\(:;]/i', '', $rule[1]);

                    // allow data:image and strict url() values only

                    if (

                        stripos($stripped, 'url(') !== false

                        && stripos($stripped, 'url(data:image') === false

                        && !preg_match($strict_url_regexp, $rule[1])

                    ) {

                        $rule[1] = '/* evil! */';

                    }

                }

                $output .= sprintf(" %s: %s;", $rule[0] , $rule[1]);

            }

            $key      = $replacements->add($output . ' ');

            $repl     = $replacements->get_replacement($key);

            $source   = substr_replace($source, $repl, $pos+1, $length);

            $last_pos = $pos2 - ($length - strlen($repl));

        }

        // add #container to each tag selector and prefix to id/class identifiers

        if ($container_id || $prefix) {

            // Exclude rcube_string_replacer pattern matches, this is needed

            // for cases like @media { body { position: fixed; } } (#5811)

            $excl     = '(?!' . substr($replacements->pattern, 1, -1) . ')';

            $regexp   = '/(^\s*|,\s*|\}\s*|\{\s*)(' . $excl . ':?[a-z0-9\._#\*\[][a-z0-9\._:\(\)#=~ \[\]"\|\>\+\$\^-]*)/im';

            $callback = function($matches) use ($container_id, $prefix) {

                $replace = $matches[2];

                if (stripos($replace, ':root') === 0) {

                    $replace = substr($replace, 5);

                }

                if ($prefix) {

                    $replace = str_replace(['.', '#'], [".$prefix", "#$prefix"], $replace);

                }

                if ($container_id) {

                    $replace = "#$container_id " . $replace;

                }

                // Remove redundant spaces (for simpler testing)

                $replace = preg_replace('/\s+/', ' ', $replace);

                return str_replace($matches[2], $replace, $matches[0]);

            };

            $source = preg_replace_callback($regexp, $callback, $source);

        }

        // replace body definition because we also stripped off the <body> tag

        if ($container_id) {

            $regexp = '/#' . preg_quote($container_id, '/') . '\s+body/i';

            $source = preg_replace($regexp, "#$container_id", $source);

        }

        // put block contents back in

        $source = $replacements->resolve($source);

        return $source;

    }

    /**

     * Explode css style. Property names will be lower-cased and trimmed.

     * Values will be trimmed. Invalid entries will be skipped.

     *

     * @param string $style CSS style

     *

     * @return array List of CSS rule pairs, e.g. [['color', 'red'], ['top', '0']]

     */

    public static function parse_css_block($style)

    {

        $pos = 0;

        // first remove comments

        while (($pos = strpos($style, '/*', $pos)) !== false) {

            $end = strpos($style, '*/', $pos+2);

            if ($end === false) {

                $style = substr($style, 0, $pos);

            }

            else {

                $style = substr_replace($style, '', $pos, $end - $pos + 2);

            }

        }

        // Replace new lines with spaces

        $style = preg_replace('/[\r\n]+/', ' ', $style);

        $style  = trim($style);

        $length = strlen($style);

        $result = [];

        $pos    = 0;

        while ($pos < $length && ($colon_pos = strpos($style, ':', $pos))) {

            // Property name

            $name = strtolower(trim(substr($style, $pos, $colon_pos - $pos)));

            // get the property value

            $q = $s = false;

            for ($i = $colon_pos + 1; $i < $length; $i++) {

                if (($style[$i] == "\"" || $style[$i] == "'") && ($i == 0 || $style[$i-1] != "\\")) {

                    if ($q == $style[$i]) {

                        $q = false;

                    }

                    else if ($q === false) {

                        $q = $style[$i];

                    }

                }

                else if ($style[$i] == "(" && !$q && ($i == 0 || $style[$i-1] != "\\")) {

                    $q = "(";

                }

                else if ($style[$i] == ")" && $q == "(" && $style[$i-1] != "\\") {

                    $q = false;

                }

                if ($q === false && (($s = $style[$i] == ';') || $i == $length - 1)) {

                    break;

                }

            }

            $value_length = $i - $colon_pos - ($s ? 1 : 0);

            $value        = trim(substr($style, $colon_pos + 1, $value_length));

            if (strlen($name) && !preg_match('/[^a-z-]/', $name) && strlen($value) && $value !== ';') {

                $result[] = [$name, $value];

            }

            $pos = $i + 1;

        }

        return $result;

    }

    /**

     * Generate CSS classes from mimetype and filename extension

     *

     * @param string $mimetype Mimetype

     * @param string $filename Filename

     *

     * @return string CSS classes separated by space

     */

    public static function file2class($mimetype, $filename)

    {

        $mimetype = strtolower($mimetype);

        $filename = strtolower($filename);

        list($primary, $secondary) = rcube_utils::explode('/', $mimetype);

        $classes = [$primary ?: 'unknown'];

        if (!empty($secondary)) {

            $classes[] = $secondary;

        }

        if (preg_match('/\.([a-z0-9]+)$/', $filename, $m)) {

            if (!in_array($m[1], $classes)) {

                $classes[] = $m[1];

            }

        }

        return implode(' ', $classes);

    }

    /**

     * Decode escaped entities used by known XSS exploits.

     * See http://downloads.securityfocus.com/vulnerabilities/exploits/26800.eml for examples

     *

     * @param string $content CSS content to decode

     *

     * @return string Decoded string

     */

    public static function xss_entity_decode($content)

    {

        $callback = function($matches) { return chr(hexdec($matches[1])); };

        $out = html_entity_decode(html_entity_decode($content));

        $out = trim(preg_replace('/(^<!--|-->$)/', '', trim($out)));

        $out = preg_replace_callback('/\\\([0-9a-f]{2,6})\s*/i', $callback, $out);

        $out = preg_replace('/\\\([^0-9a-f])/i', '\\1', $out);

        $out = preg_replace('#/\*.*\*/#Ums', '', $out);

        $out = strip_tags($out);

        return $out;

    }

    /**

     * Check if we can process not exceeding memory_limit

     *

     * @param int $need Required amount of memory

     *

     * @return bool True if memory won't be exceeded, False otherwise

     */

    public static function mem_check($need)

    {

        $mem_limit = parse_bytes(ini_get('memory_limit'));

        $memory    = function_exists('memory_get_usage') ? memory_get_usage() : 16*1024*1024; // safe value: 16MB

        return $mem_limit > 0 && $memory + $need > $mem_limit ? false : true;

    }

    /**

     * Check if working in SSL mode

     *

     * @param int  $port      HTTPS port number

     * @param bool $use_https Enables 'use_https' option checking

     *

     * @return bool True in SSL mode, False otherwise

     */

    public static function https_check($port = null, $use_https = true)

    {

        if (!empty($_SERVER['HTTPS']) && strtolower($_SERVER['HTTPS']) != 'off') {

            return true;

        }

        if (!empty($_SERVER['HTTP_X_FORWARDED_PROTO'])

            && strtolower($_SERVER['HTTP_X_FORWARDED_PROTO']) == 'https'

            && self::check_proxy_whitelist_ip()

        ) {

            return true;

        }

        if ($port && isset($_SERVER['SERVER_PORT']) && $_SERVER['SERVER_PORT'] == $port) {

            return true;

        }

        if ($use_https && rcube::get_instance()->config->get('use_https')) {

            return true;

        }

        return false;

    }

    /**

     * Check if the reported REMOTE_ADDR is in the 'proxy_whitelist' config option

     */

    public static function check_proxy_whitelist_ip() {

        return in_array($_SERVER['REMOTE_ADDR'], (array) rcube::get_instance()->config->get('proxy_whitelist', []));

    }

    /**

     * Replaces hostname variables.

     *

     * @param string $name Hostname

     * @param string $host Optional IMAP hostname

     *

     * @return string Hostname

     */

    public static function parse_host($name, $host = '')

    {

        if (!is_string($name)) {

            return $name;

        }

        // %n - host

        $n = self::server_name();

        // %t - host name without first part, e.g. %n=mail.domain.tld, %t=domain.tld

        // If %n=domain.tld then %t=domain.tld as well (remains valid)

        $t = preg_replace('/^[^.]+\.(?![^.]+$)/', '', $n);

        // %d - domain name without first part (up to domain.tld)

        $d = preg_replace('/^[^.]+\.(?![^.]+$)/', '', self::server_name('HTTP_HOST'));

        // %h - IMAP host

        $h = !empty($_SESSION['storage_host']) ? $_SESSION['storage_host'] : $host;

        // %z - IMAP domain without first part, e.g. %h=imap.domain.tld, %z=domain.tld

        // If %h=domain.tld then %z=domain.tld as well (remains valid)

        $z = preg_replace('/^[^.]+\.(?![^.]+$)/', '', $h);

        // %s - domain name after the '@' from e-mail address provided at login screen.

        //      Returns FALSE if an invalid email is provided

        $s = '';

        if (strpos($name, '%s') !== false) {

            $user_email = self::idn_to_ascii(self::get_input_value('_user', self::INPUT_POST));

            $matches    = preg_match('/(.*)@([a-z0-9\.\-\[\]\:]+)/i', $user_email, $s);

            if ($matches < 1 || filter_var($s[1]."@".$s[2], FILTER_VALIDATE_EMAIL) === false) {

                return false;

            }

            $s = $s[2];

        }

        return str_replace(['%n', '%t', '%d', '%h', '%z', '%s'], [$n, $t, $d, $h, $z, $s], $name);

    }

    /**

     * Parse host specification URI.

     *

     * @param string $host       Host URI

     * @param int    $plain_port Plain port number

     * @param int    $ssl_port   SSL port number

     *

     * @return array An array with three elements (hostname, scheme, port)

     */

    public static function parse_host_uri($host, $plain_port = null, $ssl_port = null)

    {

        if (preg_match('#^(unix|ldapi)://#i', $host, $matches)) {

            return [$host, $matches[1], -1];

        }

        $url    = parse_url($host);

        $port   = $plain_port;

        $scheme = null;

        if (!empty($url['host'])) {

            $host   = $url['host'];

            $scheme = $url['scheme'] ?? null;

            if (!empty($url['port'])) {

                $port = $url['port'];

            }

            else if (

                $scheme

                && $ssl_port

                && ($scheme === 'ssl' || ($scheme != 'tls' && $scheme[strlen($scheme) - 1] === 's'))

            ) {

                // assign SSL port to ssl://, imaps://, ldaps://, but not tls://

                $port = $ssl_port;

            }

        }

        return [$host, $scheme, $port];

    }

    /**

     * Returns the server name after checking it against trusted hostname patterns.

     *

     * Returns 'localhost' and logs a warning when the hostname is not trusted.

     *

     * @param string $type       The $_SERVER key, e.g. 'HTTP_HOST', Default: 'SERVER_NAME'.

     * @param bool   $strip_port Strip port from the host name

     *

     * @return string Server name

     */

    public static function server_name($type = null, $strip_port = true)

    {

        if (!$type) {

            $type = 'SERVER_NAME';

        }

        $name     = $_SERVER[$type] ?? '';

        $rcube    = rcube::get_instance();

        $patterns = (array) $rcube->config->get('trusted_host_patterns');

        if (!empty($name)) {

            if ($strip_port) {

                $name = preg_replace('/:\d+$/', '', $name);

            }

            if (empty($patterns)) {

                return $name;

            }

            foreach ($patterns as $pattern) {

                // the pattern might be a regular expression or just a host/domain name

                if (preg_match('/[^a-zA-Z0-9.:-]/', $pattern)) {

                    if (preg_match("/$pattern/", $name)) {

                        return $name;

                    }

                }

                else if (strtolower($name) === strtolower($pattern)) {

                    return $name;

                }

            }

            $rcube->raise_error([

                    'file' => __FILE__, 'line' => __LINE__,

                    'message' => "Specified host is not trusted. Using 'localhost'."

                ]

                , true, false

            );

        }

        return 'localhost';

    }

    /**

     * Returns remote IP address and forwarded addresses if found

     *

     * @return string Remote IP address(es)

     */

    public static function remote_ip()

    {

        $address = $_SERVER['REMOTE_ADDR'] ?? '';

        // append the NGINX X-Real-IP header, if set

        if (!empty($_SERVER['HTTP_X_REAL_IP']) && $_SERVER['HTTP_X_REAL_IP'] != $address) {

            $remote_ip[] = 'X-Real-IP: ' . $_SERVER['HTTP_X_REAL_IP'];

        }

        // append the X-Forwarded-For header, if set

        if (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) {

            $remote_ip[] = 'X-Forwarded-For: ' . $_SERVER['HTTP_X_FORWARDED_FOR'];

        }

        if (!empty($remote_ip)) {

            $address .= ' (' . implode(',', $remote_ip) . ')';

        }

        return $address;

    }

    /**

     * Returns the real remote IP address

     *

     * @return string Remote IP address

     */

    public static function remote_addr()

    {

        // Check if any of the headers are set first to improve performance

        if (!empty($_SERVER['HTTP_X_FORWARDED_FOR']) || !empty($_SERVER['HTTP_X_REAL_IP'])) {

            $proxy_whitelist = (array) rcube::get_instance()->config->get('proxy_whitelist', []);

            if (in_array($_SERVER['REMOTE_ADDR'], $proxy_whitelist)) {

                if (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) {

                    foreach (array_reverse(explode(',', $_SERVER['HTTP_X_FORWARDED_FOR'])) as $forwarded_ip) {

                        $forwarded_ip = trim($forwarded_ip);

                        if (!in_array($forwarded_ip, $proxy_whitelist)) {

                            return $forwarded_ip;

                        }

                    }

                }

                if (!empty($_SERVER['HTTP_X_REAL_IP'])) {

                    return $_SERVER['HTTP_X_REAL_IP'];

                }

            }

        }

        if (!empty($_SERVER['REMOTE_ADDR'])) {

            return $_SERVER['REMOTE_ADDR'];

        }

        return '';

    }

    /**

     * Read a specific HTTP request header.

     *

     * @param string $name Header name

     *

     * @return string|null Header value or null if not available

     */

    public static function request_header($name)

    {

        if (function_exists('apache_request_headers')) {

            $headers = apache_request_headers();

            $key     = strtoupper($name);

        }

        else {

            $headers = $_SERVER;

            $key     = 'HTTP_' . strtoupper(strtr($name, '-', '_'));

        }

        if (!empty($headers)) {

            $headers = array_change_key_case($headers, CASE_UPPER);

            return $headers[$key] ?? null;

        }

    }

    /**

     * Explode quoted string

     *

     * @param string $delimiter Delimiter expression string for preg_match()

     * @param string $string    Input string

     *

     * @return array String items

     */

    public static function explode_quoted_string($delimiter, $string)

    {

        $result = [];

        $strlen = strlen($string);

        for ($q=$p=$i=0; $i < $strlen; $i++) {

            if ($string[$i] == "\"" && (!isset($string[$i-1]) || $string[$i-1] != "\\")) {

                $q = $q ? false : true;

            }

            else if (!$q && preg_match("/$delimiter/", $string[$i])) {

                $result[] = substr($string, $p, $i - $p);

                $p = $i + 1;

            }

        }

        $result[] = (string) substr($string, $p);

        return $result;

    }

    /**

     * Improved equivalent to strtotime()

     *

     * @param string       $date     Date string

     * @param DateTimeZone $timezone Timezone to use for DateTime object

     *

     * @return int Unix timestamp

     */

    public static function strtotime($date, $timezone = null)

    {

        $date   = self::clean_datestr($date);

        $tzname = $timezone ? ' ' . $timezone->getName() : '';

        // unix timestamp

        if (is_numeric($date)) {

            return (int) $date;

        }

        // It can be very slow when provided string is not a date and very long

        if (strlen($date) > 128) {

            $date = substr($date, 0, 128);

        }

        // if date parsing fails, we have a date in non-rfc format.

        // remove token from the end and try again

        while (($ts = @strtotime($date . $tzname)) === false || $ts < 0) {

            if (($pos = strrpos($date, ' ')) === false) {

                break;

            }

            $date = rtrim(substr($date, 0, $pos));

        }

        return (int) $ts;

    }

    /**

     * Date parsing function that turns the given value into a DateTime object

     *

     * @param string       $date     Date string

     * @param DateTimeZone $timezone Timezone to use for DateTime object

     *

     * @return DateTime|false DateTime object or False on failure

     */

    public static function anytodatetime($date, $timezone = null)

    {

        if ($date instanceof DateTime) {

            return $date;

        }

        $dt   = false;

        $date = self::clean_datestr($date);

        // try to parse string with DateTime first

        if (!empty($date)) {

            try {

                $_date = preg_match('/^[0-9]+$/', $date) ? "@$date" : $date;

                $dt    = $timezone ? new DateTime($_date, $timezone) : new DateTime($_date);

            }

            catch (Exception $e) {

                // ignore

            }

        }