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<?php
declare(strict_types=1);
class IpUtil
{
public static function rangeToCidr(int $start, int $end): string
{
$value = $start ^ $end;
if (!self::isAllOnes($value))
return 'NOT SUBNET: ' . long2ip($start) . '-' . long2ip($end);
$ones = self::bitLength($value);
return long2ip($start) . '/' . (32 - $ones);
}
public static function isValidSubnetRange(int $start, int $end): bool
{
return self::isAllOnes($start ^ $end);
}
/**
* Return number of bits required to represent
* this number.
* !! Assumes given number is 2^n - 1 !!
*/
private static function bitLength(int $value): int
{
// This is log(value) / log(2)
// It should actually be $value + 1, but floating point errors
// start to happen either way at higher values, so with
// the round() thrown in, it doesn't matter...
return (int)round(log($value) / 0.69314718055995);
}
/**
* Is the given number just ones if converted to
* binary (ignoring leading zeros)?
*/
private static function isAllOnes(int $value): bool
{
return ($value & ($value + 1)) === 0;
}
/**
* Parse network range in CIDR notion, return
* ['start' => (int), 'end' => (int)] representing
* the according start and end addresses as integer
* values. Returns false on malformed input.
*
* @param string $cidr 192.168.101/24, 1.2.3.4/16, ...
* @return array{start: int, end: int}|null start and end address, false on error
*/
public static function parseCidr(string $cidr): ?array
{
$parts = explode('/', $cidr);
if (count($parts) !== 2) {
$ip = ip2long($cidr);
if ($ip === false)
return null;
return ['start' => $ip, 'end' => $ip];
}
$ip = $parts[0];
$bits = $parts[1];
if (!is_numeric($bits) || $bits < 0 || $bits > 32)
return null;
$dots = substr_count($ip, '.');
if ($dots < 3) {
$ip .= str_repeat('.0', 3 - $dots);
}
$ip = ip2long($ip);
if ($ip === false)
return null;
$bits = (int)((2 ** (32 - $bits)) - 1);
return ['start' => $ip & ~$bits, 'end' => $ip | $bits];
}
}
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