1<?php
  2/**
  3 * Class to validate and to work with IPv6 addresses
  4 *
  5 * @package Requests\Utilities
  6 */
  7
  8namespace WpOrg\Requests;
  9
 10use WpOrg\Requests\Exception\InvalidArgument;
 11use WpOrg\Requests\Utility\InputValidator;
 12
 13/**
 14 * Class to validate and to work with IPv6 addresses
 15 *
 16 * This was originally based on the PEAR class of the same name, but has been
 17 * entirely rewritten.
 18 *
 19 * @package Requests\Utilities
 20 */
 21final class Ipv6 {
 22	/**
 23	 * Uncompresses an IPv6 address
 24	 *
 25	 * RFC 4291 allows you to compress consecutive zero pieces in an address to
 26	 * '::'. This method expects a valid IPv6 address and expands the '::' to
 27	 * the required number of zero pieces.
 28	 *
 29	 * Example:  FF01::101   ->  FF01:0:0:0:0:0:0:101
 30	 *           ::1         ->  0:0:0:0:0:0:0:1
 31	 *
 32	 * @author Alexander Merz <alexander.merz@web.de>
 33	 * @author elfrink at introweb dot nl
 34	 * @author Josh Peck <jmp at joshpeck dot org>
 35	 * @copyright 2003-2005 The PHP Group
 36	 * @license https://opensource.org/licenses/bsd-license.php
 37	 *
 38	 * @param string|Stringable $ip An IPv6 address
 39	 * @return string The uncompressed IPv6 address
 40	 *
 41	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed argument is not a string or a stringable object.
 42	 */
 43	public static function uncompress($ip) {
 44		if (InputValidator::is_string_or_stringable($ip) === false) {
 45			throw InvalidArgument::create(1, '$ip', 'string|Stringable', gettype($ip));
 46		}
 47
 48		$ip = (string) $ip;
 49
 50		if (substr_count($ip, '::') !== 1) {
 51			return $ip;
 52		}
 53
 54		list($ip1, $ip2) = explode('::', $ip);
 55		$c1              = ($ip1 === '') ? -1 : substr_count($ip1, ':');
 56		$c2              = ($ip2 === '') ? -1 : substr_count($ip2, ':');
 57
 58		if (strpos($ip2, '.') !== false) {
 59			$c2++;
 60		}
 61
 62		if ($c1 === -1 && $c2 === -1) {
 63			// ::
 64			$ip = '0:0:0:0:0:0:0:0';
 65		} elseif ($c1 === -1) {
 66			// ::xxx
 67			$fill = str_repeat('0:', 7 - $c2);
 68			$ip   = str_replace('::', $fill, $ip);
 69		} elseif ($c2 === -1) {
 70			// xxx::
 71			$fill = str_repeat(':0', 7 - $c1);
 72			$ip   = str_replace('::', $fill, $ip);
 73		} else {
 74			// xxx::xxx
 75			$fill = ':' . str_repeat('0:', 6 - $c2 - $c1);
 76			$ip   = str_replace('::', $fill, $ip);
 77		}
 78
 79		return $ip;
 80	}
 81
 82	/**
 83	 * Compresses an IPv6 address
 84	 *
 85	 * RFC 4291 allows you to compress consecutive zero pieces in an address to
 86	 * '::'. This method expects a valid IPv6 address and compresses consecutive
 87	 * zero pieces to '::'.
 88	 *
 89	 * Example:  FF01:0:0:0:0:0:0:101   ->  FF01::101
 90	 *           0:0:0:0:0:0:0:1        ->  ::1
 91	 *
 92	 * @see \WpOrg\Requests\Ipv6::uncompress()
 93	 *
 94	 * @param string $ip An IPv6 address
 95	 * @return string The compressed IPv6 address
 96	 */
 97	public static function compress($ip) {
 98		// Prepare the IP to be compressed.
 99		// Note: Input validation is handled in the `uncompress()` method, which is the first call made in this method.
100		$ip       = self::uncompress($ip);
101		$ip_parts = self::split_v6_v4($ip);
102
103		// Replace all leading zeros
104		$ip_parts[0] = preg_replace('/(^|:)0+([0-9])/', '\1\2', $ip_parts[0]);
105
106		// Find bunches of zeros
107		if (preg_match_all('/(?:^|:)(?:0(?::|$))+/', $ip_parts[0], $matches, PREG_OFFSET_CAPTURE)) {
108			$max = 0;
109			$pos = null;
110			foreach ($matches[0] as $match) {
111				if (strlen($match[0]) > $max) {
112					$max = strlen($match[0]);
113					$pos = $match[1];
114				}
115			}
116
117			$ip_parts[0] = substr_replace($ip_parts[0], '::', $pos, $max);
118		}
119
120		if ($ip_parts[1] !== '') {
121			return implode(':', $ip_parts);
122		} else {
123			return $ip_parts[0];
124		}
125	}
126
127	/**
128	 * Splits an IPv6 address into the IPv6 and IPv4 representation parts
129	 *
130	 * RFC 4291 allows you to represent the last two parts of an IPv6 address
131	 * using the standard IPv4 representation
132	 *
133	 * Example:  0:0:0:0:0:0:13.1.68.3
134	 *           0:0:0:0:0:FFFF:129.144.52.38
135	 *
136	 * @param string $ip An IPv6 address
137	 * @return string[] [0] contains the IPv6 represented part, and [1] the IPv4 represented part
138	 */
139	private static function split_v6_v4($ip) {
140		if (strpos($ip, '.') !== false) {
141			$pos       = strrpos($ip, ':');
142			$ipv6_part = substr($ip, 0, $pos);
143			$ipv4_part = substr($ip, $pos + 1);
144			return [$ipv6_part, $ipv4_part];
145		} else {
146			return [$ip, ''];
147		}
148	}
149
150	/**
151	 * Checks an IPv6 address
152	 *
153	 * Checks if the given IP is a valid IPv6 address
154	 *
155	 * @param string $ip An IPv6 address
156	 * @return bool true if $ip is a valid IPv6 address
157	 */
158	public static function check_ipv6($ip) {
159		// Note: Input validation is handled in the `uncompress()` method, which is the first call made in this method.
160		$ip                = self::uncompress($ip);
161		list($ipv6, $ipv4) = self::split_v6_v4($ip);
162		$ipv6              = explode(':', $ipv6);
163		$ipv4              = explode('.', $ipv4);
164		if (count($ipv6) === 8 && count($ipv4) === 1 || count($ipv6) === 6 && count($ipv4) === 4) {
165			foreach ($ipv6 as $ipv6_part) {
166				// The section can't be empty
167				if ($ipv6_part === '') {
168					return false;
169				}
170
171				// Nor can it be over four characters
172				if (strlen($ipv6_part) > 4) {
173					return false;
174				}
175
176				// Remove leading zeros (this is safe because of the above)
177				$ipv6_part = ltrim($ipv6_part, '0');
178				if ($ipv6_part === '') {
179					$ipv6_part = '0';
180				}
181
182				// Check the value is valid
183				$value = hexdec($ipv6_part);
184				if (dechex($value) !== strtolower($ipv6_part) || $value < 0 || $value > 0xFFFF) {
185					return false;
186				}
187			}
188
189			if (count($ipv4) === 4) {
190				foreach ($ipv4 as $ipv4_part) {
191					$value = (int) $ipv4_part;
192					if ((string) $value !== $ipv4_part || $value < 0 || $value > 0xFF) {
193						return false;
194					}
195				}
196			}
197
198			return true;
199		} else {
200			return false;
201		}
202	}
203}
204