<?php
/**
* Class to validate and to work with IPv6 addresses
*
* @package Requests\Utilities
*/

namespace WpOrg\Requests;

use WpOrg\Requests\Exception\InvalidArgument;
use WpOrg\Requests\Utility\InputValidator;

/**
* 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\Utilities
*/
final class 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 https://opensource.org/licenses/bsd-license.php
*
* @param string|Stringable $ip An IPv6 address
* @return string The uncompressed IPv6 address
*
* @throws \WpOrg\Requests\Exception\InvalidArgument When the passed argument is not a string or a stringable object.
*/
public static function uncompress($ip) {
if (InputValidator::is_string_or_stringable($ip) === false) {
throw InvalidArgument::create(1, '$ip', 'string|Stringable', gettype($ip));
}

$ip = (string) $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) {
// ::
$ip = '0:0:0:0:0:0:0:0';
} elseif ($c1 === -1) {
// ::xxx
$fill = str_repeat('0:', 7 - $c2);
$ip = str_replace('::', $fill, $ip);
} elseif ($c2 === -1) {
// xxx::
$fill = str_repeat(':0', 7 - $c1);
$ip = str_replace('::', $fill, $ip);
} else {
// xxx::xxx
$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 \WpOrg\Requests\Ipv6::uncompress()
*
* @param string $ip An IPv6 address
* @return string The compressed IPv6 address
*/
public static function compress($ip) {
// Prepare the IP to be compressed.
// Note: Input validation is handled in the `uncompress()` method, which is the first call made in this method.
$ip = self::uncompress($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 $ip An IPv6 address
* @return string[] [0] contains the IPv6 represented part, and [1] the IPv4 represented part
*/
private static function split_v6_v4($ip) {
if (strpos($ip, '.') !== false) {
$pos = strrpos($ip, ':');
$ipv6_part = substr($ip, 0, $pos);
$ipv4_part = substr($ip, $pos + 1);
return [$ipv6_part, $ipv4_part];
} else {
return [$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) {
// Note: Input validation is handled in the `uncompress()` method, which is the first call made in this method.
$ip = self::uncompress($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;
}
}
}