/**
* Converts an IPv4 or IPv6 CIDR block into its range.
*
* @todo May not be the fastest way to do this.
*
* @static
* @param string $cidr CIDR block or IP address string.
* @param integer|null $bits If /bits is not specified on string they can be
* passed via this parameter instead.
* @return array A 2 element array with the low, high range
*/
public static function cidr_to_range($cidr, $bits = null)
{
if (strpos($cidr, '/') !== false) {
list($ip, $_bits) = array_pad(explode('/', $cidr, 2), 2, null);
} else {
$ip = $cidr;
$_bits = $bits;
}
if (false === filter_var($ip, FILTER_VALIDATE_IP)) {
throw new \InvalidArgumentException("IP address \"{$cidr}\" is invalid");
}
// force bit length to 32 or 128 depending on type of IP
$bitlen = false === filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4) ? 128 : 32;
if ($bits === null) {
// if no prefix is given use the length of the binary string which
// will give us 32 or 128 and result in a single IP being returned.
$bits = $_bits !== null ? $_bits : $bitlen;
}
if ($bits > $bitlen) {
throw new \InvalidArgumentException("IP address \"{$cidr}\" is invalid");
}
$ipdec = IP::inet_ptod($ip);
$ipbin = BC::bcdecbin($ipdec, $bitlen);
// calculate network
$netmask = BC::bcbindec(str_pad(str_repeat('1', $bits), $bitlen, '0'));
$ip1 = BC::bcand($ipdec, $netmask);
// calculate "broadcast" (not technically a broadcast in IPv6)
$ip2 = BC::bcor($ip1, BC::bcnot($netmask));
return array(IP::inet_dtop($ip1), IP::inet_dtop($ip2));
}