<?php
/**
 * These helpful functions were lifted from the Symfony library
 * https://github.com/symfony/http-foundation/blob/master/LICENSE
 *
 * Http utility functions.
 *
 * @author Fabien Potencier <fabien@symfony.com>
 */
namespace SilverStripe\Control\Util;

/**
 * Http utility functions.
 *
 * @author Fabien Potencier <fabien@symfony.com>
 */
class IPUtils
{
    /**
     * This class should not be instantiated.
     */
    private function __construct()
    {
    }
    /**
     * Checks if an IPv4 or IPv6 address is contained in the list of given IPs or subnets.
     *
     * @param string       $requestIP IP to check
     * @param string|array $ips       List of IPs or subnets (can be a string if only a single one)
     *
     * @return bool Whether the IP is valid
     *
     * @package framework
     * @subpackage core
     */
    public static function checkIP($requestIP, $ips)
    {
        if (!is_array($ips)) {
            $ips = [$ips];
        }

        $method = substr_count($requestIP ?? '', ':') > 1 ? 'checkIP6' : 'checkIP4';

        foreach ($ips as $ip) {
            if (self::$method($requestIP, trim($ip ?? ''))) {
                return true;
            }
        }

        return false;
    }
    /**
     * Compares two IPv4 addresses.
     * In case a subnet is given, it checks if it contains the request IP.
     *
     * @param string $requestIP IPv4 address to check
     * @param string $ip        IPv4 address or subnet in CIDR notation
     *
     * @return bool Whether the request IP matches the IP, or whether the request IP is within the CIDR subnet
     */
    public static function checkIP4($requestIP, $ip)
    {
        if (!filter_var($requestIP, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4)) {
            return false;
        }

        if (false !== strpos($ip ?? '', '/')) {
            list($address, $netmask) = explode('/', $ip ?? '', 2);

            if ($netmask === '0') {
                return filter_var($address, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4);
            }

            if ($netmask < 0 || $netmask > 32) {
                return false;
            }
        } else {
            $address = $ip;
            $netmask = 32;
        }

        return 0 === substr_compare(sprintf('%032b', ip2long($requestIP ?? '')), sprintf('%032b', ip2long($address ?? '')), 0, $netmask);
    }
    /**
     * Compares two IPv6 addresses.
     * In case a subnet is given, it checks if it contains the request IP.
     *
     * @author David Soria Parra <dsp@php.net>
     *
     * @see https://github.com/dsp/v6tools
     *
     * @param string $requestIP IPv6 address to check
     * @param string $ip        IPv6 address or subnet in CIDR notation
     *
     * @return bool Whether the IP is valid
     *
     * @throws \RuntimeException When IPV6 support is not enabled
     */
    public static function checkIP6($requestIP, $ip)
    {
        if (!((extension_loaded('sockets') && defined('AF_INET6')) || @inet_pton('::1'))) {
            throw new \RuntimeException('Unable to check IPv6. Check that PHP was not compiled with option "disable-ipv6".');
        }

        if (false !== strpos($ip ?? '', '/')) {
            list($address, $netmask) = explode('/', $ip ?? '', 2);

            if ($netmask < 1 || $netmask > 128) {
                return false;
            }
        } else {
            $address = $ip;
            $netmask = 128;
        }

        $bytesAddr = unpack('n*', @inet_pton($address ?? ''));
        $bytesTest = unpack('n*', @inet_pton($requestIP ?? ''));

        if (!$bytesAddr || !$bytesTest) {
            return false;
        }

        for ($i = 1, $ceil = ceil($netmask / 16); $i <= $ceil; ++$i) {
            $left = $netmask - 16 * ($i - 1);
            $left = ($left <= 16) ? $left : 16;
            $mask = ~(0xffff >> $left) & 0xffff;
            if (($bytesAddr[$i] & $mask) != ($bytesTest[$i] & $mask)) {
                return false;
            }
        }

        return true;
    }
}