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<?php
class IpUtil
{
public static function rangeToCidr($start, $end)
{
$value = (int)$start ^ (int)$end;
if (!self::isAllOnes($value))
return 'NOT SUBNET: ' . long2ip($start) . '-' . long2ip($end);
$ones = self::countOnes($value);
return long2ip($start) . '/' . (32 - $ones);
}
public static function isValidSubnetRange($start, $end)
{
return self::isAllOnes((int)$start ^ (int)$end);
}
/**
* Return number of one bits required to represent
* this number. Assumes given number is 2^n - 1.
*/
private static function countOnes($value)
{
// This is log(value) / log(2)
// It should actually be $value + 1, but floating point errors
// start to happen either way at higher values, so with
// the round() thrown in, it doesn't matter...
return round(log($value) / 0.69314718055995);
}
/**
* Is the given number just ones if converted to
* binary (ignoring leading zeros)?
*/
private static function isAllOnes($value)
{
return ($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 $cidr 192.168.101/24, 1.2.3.4/16, ...
* @return array|false start and end address, false on error
*/
public static function parseCidr($cidr)
{
$parts = explode('/', $cidr);
if (count($parts) !== 2) {
$ip = ip2long($cidr);
if ($ip === false)
return false;
if (PHP_INT_SIZE === 4) {
$ip = sprintf('%u', $ip);
}
return ['start' => $ip, 'end' => $ip];
}
$ip = $parts[0];
$bits = $parts[1];
if (!is_numeric($bits) || $bits < 0 || $bits > 32)
return false;
$dots = substr_count($ip, '.');
if ($dots < 3) {
$ip .= str_repeat('.0', 3 - $dots);
}
$ip = ip2long($ip);
if ($ip === false)
return false;
$bits = pow(2, 32 - $bits) - 1;
if (PHP_INT_SIZE === 4)
return ['start' => sprintf('%u', $ip & ~$bits), 'end' => sprintf('%u', $ip | $bits)];
return ['start' => $ip & ~$bits, 'end' => $ip | $bits];
}
}
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