Ipv6::compress( string $ip ): string

Compresses an IPv6 address

Description

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 also

Parameters

$ipstringrequired
An IPv6 address

Return

string The compressed IPv6 address

Source

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];
	}
}

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