<?php

/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier <fabien@symfony.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Symfony\Component\HttpFoundation;

/**
 * Http utility functions.
 *
 * @author Fabien Potencier <fabien@symfony.com>
 */
class IpUtils
{
    private static $checkedIps = [];

    /**
     * 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 $ips       List of IPs or subnets (can be a string if only a single one)
     *
     * @return bool Whether the IP is valid
     */
    public static function checkIp($requestIp, $ips)
    {
        if (null === $requestIp) {
            return false;
        }

        if (!\is_array($ips)) {
            $ips = [$ips];
        }

        $method = substr_count($requestIp, ':') > 1 ? 'checkIp6' : 'checkIp4';

        foreach ($ips as $ip) {
            if (self::$method($requestIp, $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)
    {
        $cacheKey = $requestIp.'-'.$ip;
        if (isset(self::$checkedIps[$cacheKey])) {
            return self::$checkedIps[$cacheKey];
        }

        if (!filter_var($requestIp, \FILTER_VALIDATE_IP, \FILTER_FLAG_IPV4)) {
            return self::$checkedIps[$cacheKey] = false;
        }

        if (str_contains($ip, '/')) {
            [$address, $netmask] = explode('/', $ip, 2);

            if ('0' === $netmask) {
                return self::$checkedIps[$cacheKey] = filter_var($address, \FILTER_VALIDATE_IP, \FILTER_FLAG_IPV4);
            }

            if ($netmask < 0 || $netmask > 32) {
                return self::$checkedIps[$cacheKey] = false;
            }
        } else {
            $address = $ip;
            $netmask = 32;
        }

        if (false === ip2long($address)) {
            return self::$checkedIps[$cacheKey] = false;
        }

        return self::$checkedIps[$cacheKey] = 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 at php dot 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)
    {
        $cacheKey = $requestIp.'-'.$ip;
        if (isset(self::$checkedIps[$cacheKey])) {
            return self::$checkedIps[$cacheKey];
        }

        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 (str_contains($ip, '/')) {
            [$address, $netmask] = explode('/', $ip, 2);

            if ('0' === $netmask) {
                return (bool) unpack('n*', @inet_pton($address));
            }

            if ($netmask < 1 || $netmask > 128) {
                return self::$checkedIps[$cacheKey] = false;
            }
        } else {
            $address = $ip;
            $netmask = 128;
        }

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

        if (!$bytesAddr || !$bytesTest) {
            return self::$checkedIps[$cacheKey] = 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] & $mask)) {
                return self::$checkedIps[$cacheKey] = false;
            }
        }

        return self::$checkedIps[$cacheKey] = true;
    }

    /**
     * Anonymizes an IP/IPv6.
     *
     * Removes the last byte for v4 and the last 8 bytes for v6 IPs
     */
    public static function anonymize(string $ip): string
    {
        $wrappedIPv6 = false;
        if ('[' === substr($ip, 0, 1) && ']' === substr($ip, -1, 1)) {
            $wrappedIPv6 = true;
            $ip = substr($ip, 1, -1);
        }

        $packedAddress = inet_pton($ip);
        if (4 === \strlen($packedAddress)) {
            $mask = '255.255.255.0';
        } elseif ($ip === inet_ntop($packedAddress & inet_pton('::ffff:ffff:ffff'))) {
            $mask = '::ffff:ffff:ff00';
        } elseif ($ip === inet_ntop($packedAddress & inet_pton('::ffff:ffff'))) {
            $mask = '::ffff:ff00';
        } else {
            $mask = 'ffff:ffff:ffff:ffff:0000:0000:0000:0000';
        }
        $ip = inet_ntop($packedAddress & inet_pton($mask));

        if ($wrappedIPv6) {
            $ip = '['.$ip.']';
        }

        return $ip;
    }
}