<?php

/**

 * Class to validate and to work with IPv6 addresses

 *

 * @package Requests

 * @subpackage Utilities

 */

/**

 * Class to validate and to work with IPv6 addresses

 *

 * This was originally based on the PEAR class of the same name, but has been

 * entirely rewritten.

 *

 * @package Requests

 * @subpackage Utilities

 */

class Requests_IPv6 {

	/**

	 * Uncompresses an IPv6 address

	 *

	 * RFC 4291 allows you to compress consecutive zero pieces in an address to

	 * '::'. This method expects a valid IPv6 address and expands the '::' to

	 * the required number of zero pieces.

	 *

	 * Example:  FF01::101   ->  FF01:0:0:0:0:0:0:101

	 *           ::1         ->  0:0:0:0:0:0:0:1

	 *

	 * @author Alexander Merz <alexander.merz@web.de>

	 * @author elfrink at introweb dot nl

	 * @author Josh Peck <jmp at joshpeck dot org>

	 * @copyright 2003-2005 The PHP Group

	 * @license http://www.opensource.org/licenses/bsd-license.php

	 * @param string $ip An IPv6 address

	 * @return string The uncompressed IPv6 address

	 */

	public static function uncompress($ip) {

		if (substr_count($ip, '::') !== 1) {

			return $ip;

		}

		list($ip1, $ip2) = explode('::', $ip);

		$c1 = ($ip1 === '') ? -1 : substr_count($ip1, ':');

		$c2 = ($ip2 === '') ? -1 : substr_count($ip2, ':');

		if (strpos($ip2, '.') !== false) {

			$c2++;

		}

		// ::

		if ($c1 === -1 && $c2 === -1) {

			$ip = '0:0:0:0:0:0:0:0';

		}

		// ::xxx

		else if ($c1 === -1) {

			$fill = str_repeat('0:', 7 - $c2);

			$ip = str_replace('::', $fill, $ip);

		}

		// xxx::

		else if ($c2 === -1) {

			$fill = str_repeat(':0', 7 - $c1);

			$ip = str_replace('::', $fill, $ip);

		}

		// xxx::xxx

		else {

			$fill = ':' . str_repeat('0:', 6 - $c2 - $c1);

			$ip = str_replace('::', $fill, $ip);

		}

		return $ip;

	}

	/**

	 * Compresses an IPv6 address

	 *

	 * RFC 4291 allows you to compress consecutive zero pieces in an address to

	 * '::'. This method expects a valid IPv6 address and compresses consecutive

	 * zero pieces to '::'.

	 *

	 * Example:  FF01:0:0:0:0:0:0:101   ->  FF01::101

	 *           0:0:0:0:0:0:0:1        ->  ::1

	 *

	 * @see uncompress()

	 * @param string $ip An IPv6 address

	 * @return string The compressed IPv6 address

	 */

	public static function compress($ip) {

		// Prepare the IP to be compressed

		$ip = self::uncompress($ip);

		$ip_parts = self::split_v6_v4($ip);

		// Replace all leading zeros

		$ip_parts[0] = preg_replace('/(^|:)0+([0-9])/', '\1\2', $ip_parts[0]);

		// Find bunches of zeros

		if (preg_match_all('/(?:^|:)(?:0(?::|$))+/', $ip_parts[0], $matches, PREG_OFFSET_CAPTURE)) {

			$max = 0;

			$pos = null;

			foreach ($matches[0] as $match) {

				if (strlen($match[0]) > $max) {

					$max = strlen($match[0]);

					$pos = $match[1];

				}

			}

			$ip_parts[0] = substr_replace($ip_parts[0], '::', $pos, $max);

		}

		if ($ip_parts[1] !== '') {

			return implode(':', $ip_parts);

		}

		else {

			return $ip_parts[0];

		}

	}

	/**

	 * Splits an IPv6 address into the IPv6 and IPv4 representation parts

	 *

	 * RFC 4291 allows you to represent the last two parts of an IPv6 address

	 * using the standard IPv4 representation

	 *

	 * Example:  0:0:0:0:0:0:13.1.68.3

	 *           0:0:0:0:0:FFFF:129.144.52.38

	 *

	 * @param string $ip An IPv6 address

	 * @return string[] [0] contains the IPv6 represented part, and [1] the IPv4 represented part

	 */

	protected static function split_v6_v4($ip) {

		if (strpos($ip, '.') !== false) {

			$pos = strrpos($ip, ':');

			$ipv6_part = substr($ip, 0, $pos);

			$ipv4_part = substr($ip, $pos + 1);

			return array($ipv6_part, $ipv4_part);

		}

		else {

			return array($ip, '');

		}

	}

	/**

	 * Checks an IPv6 address

	 *

	 * Checks if the given IP is a valid IPv6 address

	 *

	 * @param string $ip An IPv6 address

	 * @return bool true if $ip is a valid IPv6 address

	 */

	public static function check_ipv6($ip) {

		$ip = self::uncompress($ip);

		list($ipv6, $ipv4) = self::split_v6_v4($ip);

		$ipv6 = explode(':', $ipv6);

		$ipv4 = explode('.', $ipv4);

		if (count($ipv6) === 8 && count($ipv4) === 1 || count($ipv6) === 6 && count($ipv4) === 4) {

			foreach ($ipv6 as $ipv6_part) {

				// The section can't be empty

				if ($ipv6_part === '') {

					return false;

				}

				// Nor can it be over four characters

				if (strlen($ipv6_part) > 4) {

					return false;

				}

				// Remove leading zeros (this is safe because of the above)

				$ipv6_part = ltrim($ipv6_part, '0');

				if ($ipv6_part === '') {

					$ipv6_part = '0';

				}

				// Check the value is valid

				$value = hexdec($ipv6_part);

				if (dechex($value) !== strtolower($ipv6_part) || $value < 0 || $value > 0xFFFF) {

					return false;

				}

			}

			if (count($ipv4) === 4) {

				foreach ($ipv4 as $ipv4_part) {

					$value = (int) $ipv4_part;

					if ((string) $value !== $ipv4_part || $value < 0 || $value > 0xFF) {

						return false;

					}

				}

			}

			return true;

		}

		else {

			return false;

		}

	}

}