Proyectos de Subversion Moodle

<?php

// This file is part of Moodle - http://moodle.org/

//

// Moodle is free software: you can redistribute it and/or modify

// it under the terms of the GNU General Public License as published by

// the Free Software Foundation, either version 3 of the License, or

// (at your option) any later version.

//

// Moodle 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 General Public License for more details.

//

// You should have received a copy of the GNU General Public License

// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**

 * Contains a simple class providing some useful internet protocol-related functions.

 *

 * @package   core

 * @copyright 2016 Jake Dallimore

 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 * @author    Jake Dallimore <jrhdallimore@gmail.com>

 */

namespace core;

defined('MOODLE_INTERNAL') || exit();

/**

 * Static helper class providing some useful internet-protocol-related functions.

 *

 * @package   core

 * @copyright 2016 Jake Dallimore

 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 * @author    Jake Dallimore <jrhdallimore@gmail.com>

 */

final class ip_utils {

    /**

     * Syntax checking for domain names, including fully qualified domain names.

     *

     * This function does not verify the existence of the domain name. It only verifies syntactic correctness.

     * This is based on RFC1034/1035 and does not provide support for validation of internationalised domain names (IDNs).

     * All IDNs must be prior-converted to their ascii-compatible encoding before being passed to this function.

     *

     * @param string $domainname the input string to check.

     * @return bool true if the string has valid syntax, false otherwise.

     */

    public static function is_domain_name($domainname) {

        if (!is_string($domainname)) {

            return false;

        }

        // Usually the trailing dot (null label) is omitted, but is valid if supplied. We'll just remove it and validate as normal.

        $domainname = rtrim($domainname, '.');

        // The entire name cannot exceed 253 ascii characters (255 octets, less the leading label-length byte and null label byte).

        if (strlen($domainname) > 253) {

            return false;

        }

        // Tertiary domain labels can have 63 octets max, and must not have begin or end with a hyphen.

        // The TLD label cannot begin with a number, but otherwise, is only loosely restricted here (TLD list is not checked).

        $domaintertiary = '([a-zA-Z0-9](([a-zA-Z0-9-]{0,61})[a-zA-Z0-9])?\.)*';

        $domaintoplevel = '([a-zA-Z](([a-zA-Z0-9-]*)[a-zA-Z0-9])?)';

        $address = '(' . $domaintertiary .  $domaintoplevel . ')';

        $regexp = '#^' . $address . '$#i'; // Case insensitive matching.

        return preg_match($regexp, $domainname, $match) == true; // False for error, 0 for no match - we treat the same.

    }

    /**

     * Checks whether the input string is a valid wildcard domain matching pattern.

     *

     * A domain matching pattern is essentially a domain name with a single, leading wildcard (*) label, and at least one other

     * label. The wildcard label is considered to match at least one label at or above (to the left of) its position in the string,

     * but will not match the trailing domain (everything to its right).

     *

     * The string must be dot-separated, and the whole pattern must follow the domain name syntax rules defined in RFC1034/1035.

     * Namely, the character type (ascii), total-length (253) and label-length (63) restrictions. This function only confirms

     * syntactic correctness. It does not check for the existence of the domain/subdomains.

     *

     * For example, the string '*.example.com' is a pattern deemed to match any direct subdomain of

     * example.com (such as test.example.com), any higher level subdomains (e.g. another.test.example.com) but will not match

     * the 'example.com' domain itself.

     *

     * @param string $pattern the string to check.

     * @return bool true if the input string is a valid domain wildcard matching pattern, false otherwise.

     */

    public static function is_domain_matching_pattern($pattern) {

        if (!is_string($pattern)) {

            return false;

        }

        // Usually the trailing dot (null label) is omitted, but is valid if supplied. We'll just remove it and validate as normal.

        $pattern = rtrim($pattern, '.');

        // The entire name cannot exceed 253 ascii characters (255 octets, less the leading label-length byte and null label byte).

        if (strlen($pattern) > 253) {

            return false;

        }

        // A valid pattern must left-positioned wildcard symbol (*).

        // Tertiary domain labels can have 63 octets max, and must not have begin or end with a hyphen.

        // The TLD label cannot begin with a number, but otherwise, is only loosely restricted here (TLD list is not checked).

        $wildcard = '((\*)\.){1}';

        $domaintertiary = '([a-zA-Z0-9](([a-zA-Z0-9-]{0,61})[a-zA-Z0-9])?\.)*';

        $domaintoplevel = '([a-zA-Z](([a-zA-Z0-9-]*)[a-zA-Z0-9])?)';

        $address = '(' . $wildcard . $domaintertiary .  $domaintoplevel . ')';

        $regexp = '#^' . $address . '$#i'; // Case insensitive matching.

        return preg_match($regexp, $pattern, $match) == true; // False for error, 0 for no match - we treat the same.

    }

    /**

     * Syntax validation for IP addresses, supporting both IPv4 and Ipv6 formats.

     *

     * @param string $address the address to check.

     * @return bool true if the address is a valid IPv4 of IPv6 address, false otherwise.

     */

    public static function is_ip_address($address) {

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

    }

    /**

     * Syntax validation for IPv4 addresses.

     *

     * @param string $address the address to check.

     * @return bool true if the address is a valid IPv4 address, false otherwise.

     */

    public static function is_ipv4_address($address) {

        return filter_var($address, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4) !== false;

    }

    /**

     * Syntax checking for IPv4 address ranges.

     * Supports CIDR notation and last-group ranges.

     * Eg. 127.0.0.0/24 or 127.0.0.80-255

     *

     * @param string $addressrange the address range to check.

     * @return bool true if the string is a valid range representation, false otherwise.

     */

    public static function is_ipv4_range($addressrange) {

        // Check CIDR notation.

        if (preg_match('#^(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})\/(\d{1,2})$#', $addressrange, $match)) {

            $address = "{$match[1]}.{$match[2]}.{$match[3]}.{$match[4]}";

            return self::is_ipv4_address($address) && $match[5] <= 32;

        }

        // Check last-group notation.

        if (preg_match('#^(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})-(\d{1,3})$#', $addressrange, $match)) {

            $address = "{$match[1]}.{$match[2]}.{$match[3]}.{$match[4]}";

            return self::is_ipv4_address($address) && $match[5] <= 255 && $match[5] >= $match[4];

        }

        return false;

    }

    /**

     * Syntax validation for IPv6 addresses.

     * This function does not check whether the address is assigned, only its syntactical correctness.

     *

     * @param string $address the address to check.

     * @return bool true if the address is a valid IPv6 address, false otherwise.

     */

    public static function is_ipv6_address($address) {

        return filter_var($address, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6) !== false;

    }

    /**

     * Syntax validation for IPv6 address ranges.

     * Supports CIDR notation and last-group ranges.

     * Eg. fe80::d98c/64 or fe80::d98c-ffee

     *

     * @param string $addressrange the IPv6 address range to check.

     * @return bool true if the string is a valid range representation, false otherwise.

     */

    public static function is_ipv6_range($addressrange) {

        // Check CIDR notation.

        $ipv6parts = explode('/', $addressrange);

        if (count($ipv6parts) == 2) {

            $range = (int)$ipv6parts[1];

            return self::is_ipv6_address($ipv6parts[0]) && (string)$range === $ipv6parts[1] && $range >= 0 && $range <= 128;

        }

        // Check last-group notation.

        $ipv6parts = explode('-', $addressrange);

        if (count($ipv6parts) == 2) {

            $addressparts = explode(':', $ipv6parts[0]);

            $rangestart = $addressparts[count($addressparts) - 1];

            $rangeend = $ipv6parts[1];

            return self::is_ipv6_address($ipv6parts[0]) && ctype_xdigit($rangestart) && ctype_xdigit($rangeend)

            && strlen($rangeend) <= 4 && strlen($rangestart) <= 4 && hexdec($rangeend) >= hexdec($rangestart);

        }

        return false;

    }

    /**

     * Checks the domain name against a list of allowed domains. The list of allowed domains may use wildcards

     * that match {@see is_domain_matching_pattern()}. Domains are compared in a case-insensitive manner

     *

     * @param  string $domain Domain address

     * @param  array $alloweddomains An array of allowed domains.

     * @return boolean True if the domain matches one of the entries in the allowed domains list.

     */

    public static function is_domain_in_allowed_list($domain, $alloweddomains) {

        if (!self::is_domain_name($domain)) {

            return false;

        }

        foreach ($alloweddomains as $alloweddomain) {

            if (strpos($alloweddomain, '*') !== false) {

                if (!self::is_domain_matching_pattern($alloweddomain)) {

                    continue;

                }

                // Use of wildcard for possible subdomains.

                $escapeperiods = str_replace('.', '\.', $alloweddomain);

                $replacewildcard = str_replace('*', '.*', $escapeperiods);

                $ultimatepattern = '/' . $replacewildcard . '$/i';

                if (preg_match($ultimatepattern, $domain)) {

                    return true;

                }

            } else {

                if (!self::is_domain_name($alloweddomain)) {

                    continue;

                }

                // Strict domain setting.

                if (strcasecmp($domain, $alloweddomain) === 0) {

                    return true;

                }

            }

        }

        return false;

    }

    /**

     * Is an ip in a given list of subnets?

     *

     * @param string $ip - the IP to test against the list

     * @param string $list - the list of IP subnets

     * @param string $delim a delimiter of the list

     * @return bool

     */

    public static function is_ip_in_subnet_list($ip, $list, $delim = "\n") {

        $list = explode($delim, $list);

        foreach ($list as $line) {

            $tokens = explode('#', $line);

            $subnet = trim($tokens[0]);

            if (address_in_subnet($ip, $subnet)) {

                return true;

            }

        }

        return false;

    }

    /**

     * Return IP address for given hostname, or null on failure

     *

     * @param string $hostname

     * @return string|null

     */

    public static function get_ip_address(string $hostname): ?string {

        if (self::is_domain_name($hostname)) {

            $address = gethostbyname($hostname);

            // If address is different from hostname, we have success.

            if (strcasecmp($address, $hostname) !== 0) {

                return $address;

            }

        }

        return null;

    }

    /**

     * Normalize internet address.

     *

     * Accepted input formats are :

     * - a valid range or full ip address (e.g.: 192.168.0.0/16, fe80::ffff, 127.0.0.1 or fe80:fe80:fe80:fe80:fe80:fe80:fe80:fe80)

     * - a valid domain name or pattern (e.g.: www.moodle.com or *.moodle.org)

     *

     * Convert forbidden syntaxes since MDL-74289 to allowed values. For examples:

     * - 192.168. => 192.168.0.0/16

     * - .domain.tld => *.domain.tld

     *

     * @param string $address The input string to normalize.

     *

     * @return string If $address is not normalizable, an empty string is returned.

     */

    public static function normalize_internet_address(string $address): string {

        $address = str_replace([" ", "\n", "\r", "\t", "\v", "\x00"], '', strtolower($address));

        // Replace previous allowed "192.168." format to CIDR format (192.168.0.0/16).

        if (str_ends_with($address, '.') && preg_match('/^[0-9\.]+$/', $address) === 1) {

            $count = substr_count($address, '.');

            // Remove final dot.

            $address = substr($address, 0, -1);

            // Fill address with missing ".0".

            $address .= str_repeat('.0', 4 - $count);

            // Add subnet mask.

            $address .= '/' . ($count * 8);

        }

        if (self::is_ip_address($address) ||

            self::is_ipv4_range($address) || self::is_ipv6_range($address)) {

            // Keep full or range ip addresses.

            return $address;

        }

        // Replace previous allowed ".domain.tld" format to "*.domain.tld" format.

        if (str_starts_with($address, '.')) {

            $address = '*'.$address;

        }

        // Usually the trailing dot (null label) is omitted, but is valid if supplied. We'll just remove it and validate as normal.

        $address = rtrim($address, '.');

        if (self::is_domain_name($address) || self::is_domain_matching_pattern($address)) {

            // Keep valid or pattern domain name.

            return $address;

        }

        // Return empty string for invalid values.

        return '';

    }

    /**

     * Normalize a list of internet addresses.

     *

     * This function will:

     * - normalize internet addresses {@see normalize_internet_address()}

     * - remove invalid values

     * - remove duplicate values

     *

     * @param string $addresslist A string representing a list of internet addresses separated by a common value.

     * @param string $separator A separator character used within the list string.

     *

     * @return string

     */

    public static function normalize_internet_address_list(string $addresslist, string $separator = ','): string {

        $addresses = [];

        foreach (explode($separator, $addresslist) as $value) {

            $address = self::normalize_internet_address($value);

            if (empty($address)) {

                // Ignore invalid input.

                continue;

            }

            if (in_array($address, $addresses, true)) {

                // Ignore duplicate value.

                continue;

            }

            $addresses[] = $address;

        }

        return implode($separator, $addresses);

    }

}