nextcloud / server

	 * @param int $maskBits

	 * @return string

	 */

	private function getIPv4Subnet($ip,

								   $maskBits = 32) {

		$binary = \inet_pton($ip);

		for ($i = 32; $i > $maskBits; $i -= 8) {

			$j = \intdiv($i, 8) - 1;

			$k = (int) \min(8, $i - $maskBits);

			$mask = (0xff - ((pow(2, $k)) - 1));

			$int = \unpack('C', $binary[$j]);

			$binary[$j] = \pack('C', $int[1] & $mask);

		}

		return \inet_ntop($binary).'/'.$maskBits;

	}

	/**

	 * Return the given subnet for an IPv6 address and mask bits

	 * @param int $maskBits

	 * @return string

	 */

	private function getIPv6Subnet($ip, $maskBits = 48) {

		$binary = \inet_pton($ip);

		for ($i = 128; $i > $maskBits; $i -= 8) {

			$j = \intdiv($i, 8) - 1;

			$k = (int) \min(8, $i - $maskBits);

			$mask = (0xff - ((pow(2, $k)) - 1));

			$int = \unpack('C', $binary[$j]);

			$binary[$j] = \pack('C', $int[1] & $mask);

		}

		return \inet_ntop($binary).'/'.$maskBits;

	}

	/**

	 * Gets either the /32 (IPv4) or the /128 (IPv6) subnet of an IP address