Not terribly useful, but the bitshifting was kinda fun.
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/** * Determine if a given IP belongs to a given subnet (written in CIDR notation) * * @param string IP address in dotted notation (X.X.X.X) * @param string IP subnet in CIDR notation (X.X.X.X/XX) * @return bool whether or not the IP belongs to the subnet * @author Poprocks */ function __cidr_match( $ip, $cidr ) { list( $subnet, $mask ) = explode( '/', $cidr ); return ( ip2long( $ip ) & ~ ( ( 1 << ( 32 - $mask ) ) - 1 ) ) == ( ip2long( $subnet ) >> ( 32 - $mask ) ) << ( 32 - $mask ); } /** * Match a given IP address in an array of subnets * * @param string IP address in dotted notation (X.X.X.X) * @param array IP subnets in CIDR notation(array("X.X.X.X/XX", "Y.Y.Y.Y/YY") * @param string optional string noting which subnet the IP matched, if any. Will return the first match present * @return bool whether or not the IP belongs in any of the subnets * @author Poprocks */ function cidr_match( $ip, $cidrs, &$cidr_matched = null ) { if ( ! is_array( $cidrs ) ) { $cidrs = array( $cidrs ); } foreach ( $cidrs as $cidr ) { if ( __cidr_match( $ip, $cidr ) ) { $cidr_matched = $cidr; return true; } } return false; } |