wp_kses_check_attr_val( string $value, string $vless, string $checkname, mixed $checkvalue ): bool

1655function wp_kses_check_attr_val( $value, $vless, $checkname, $checkvalue ) {1656	$ok = true;1657 1658	switch ( strtolower( $checkname ) ) {1659		case 'maxlen':1660			/*1661			 * The maxlen check makes sure that the attribute value has a length not1662			 * greater than the given value. This can be used to avoid Buffer Overflows1663			 * in WWW clients and various Internet servers.1664			 */1665 1666			if ( strlen( $value ) > $checkvalue ) {1667				$ok = false;1668			}1669			break;1670 1671		case 'minlen':1672			/*1673			 * The minlen check makes sure that the attribute value has a length not1674			 * smaller than the given value.1675			 */1676 1677			if ( strlen( $value ) < $checkvalue ) {1678				$ok = false;1679			}1680			break;1681 1682		case 'maxval':1683			/*1684			 * The maxval check does two things: it checks that the attribute value is1685			 * an integer from 0 and up, without an excessive amount of zeroes or1686			 * whitespace (to avoid Buffer Overflows). It also checks that the attribute1687			 * value is not greater than the given value.1688			 * This check can be used to avoid Denial of Service attacks.1689			 */1690 1691			if ( ! preg_match( '/^\s{0,6}[0-9]{1,6}\s{0,6}$/', $value ) ) {1692				$ok = false;1693			}1694			if ( $value > $checkvalue ) {1695				$ok = false;1696			}1697			break;1698 1699		case 'minval':1700			/*1701			 * The minval check makes sure that the attribute value is a positive integer,1702			 * and that it is not smaller than the given value.1703			 */1704 1705			if ( ! preg_match( '/^\s{0,6}[0-9]{1,6}\s{0,6}$/', $value ) ) {1706				$ok = false;1707			}1708			if ( $value < $checkvalue ) {1709				$ok = false;1710			}1711			break;1712 1713		case 'valueless':1714			/*1715			 * The valueless check makes sure if the attribute has a value1716			 * (like `<a href="blah">`) or not (`<option selected>`). If the given value1717			 * is a "y" or a "Y", the attribute must not have a value.1718			 * If the given value is an "n" or an "N", the attribute must have a value.1719			 */1720 1721			if ( strtolower( $checkvalue ) !== $vless ) {1722				$ok = false;1723			}1724			break;1725 1726		case 'values':1727			/*1728			 * The values check is used when you want to make sure that the attribute1729			 * has one of the given values.1730			 */1731 1732			if ( false === array_search( strtolower( $value ), $checkvalue, true ) ) {1733				$ok = false;1734			}