IPv6

21class IPv622{23    /**24     * Uncompresses an IPv6 address25     *26     * RFC 4291 allows you to compress consecutive zero pieces in an address to27     * '::'. This method expects a valid IPv6 address and expands the '::' to28     * the required number of zero pieces.29     *30     * Example:  FF01::101   ->  FF01:0:0:0:0:0:0:10131     *           ::1         ->  0:0:0:0:0:0:0:132     *33     * @author Alexander Merz <[email protected]>34     * @author elfrink at introweb dot nl35     * @author Josh Peck <jmp at joshpeck dot org>36     * @copyright 2003-2005 The PHP Group37     * @license http://www.opensource.org/licenses/bsd-license.php38     * @param string $ip An IPv6 address39     * @return string The uncompressed IPv6 address40     */41    public static function uncompress(string $ip)42    {43        $c1 = -1;44        $c2 = -1;45        if (substr_count($ip, '::') === 1) {46            [$ip1, $ip2] = explode('::', $ip);47            if ($ip1 === '') {48                $c1 = -1;49            } else {50                $c1 = substr_count($ip1, ':');51            }52            if ($ip2 === '') {53                $c2 = -1;54            } else {55                $c2 = substr_count($ip2, ':');56            }57            if (strpos($ip2, '.') !== false) {58                $c2++;59            }60            // ::61            if ($c1 === -1 && $c2 === -1) {62                $ip = '0:0:0:0:0:0:0:0';63            }64            // ::xxx65            elseif ($c1 === -1) {66                $fill = str_repeat('0:', 7 - $c2);67                $ip = str_replace('::', $fill, $ip);68            }69            // xxx::70            elseif ($c2 === -1) {71                $fill = str_repeat(':0', 7 - $c1);72                $ip = str_replace('::', $fill, $ip);73            }74            // xxx::xxx75            else {76                $fill = ':' . str_repeat('0:', 6 - $c2 - $c1);77                $ip = str_replace('::', $fill, $ip);78            }79        }80        return $ip;81    }82 83    /**84     * Compresses an IPv6 address85     *86     * RFC 4291 allows you to compress consecutive zero pieces in an address to87     * '::'. This method expects a valid IPv6 address and compresses consecutive88     * zero pieces to '::'.89     *90     * Example:  FF01:0:0:0:0:0:0:101   ->  FF01::10191     *           0:0:0:0:0:0:0:1        ->  ::192     *93     * @see uncompress()94     * @param string $ip An IPv6 address95     * @return string The compressed IPv6 address96     */97    public static function compress(string $ip)98    {99        // Prepare the IP to be compressed100        $ip = self::uncompress($ip);