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<?php
namespace Laminas\Http\Header;
use function ord;
use function strlen;
final class HeaderValue
{
/**
* Private constructor; non-instantiable.
*/
private function __construct()
{
}
/**
* Filter a header value
*
* Ensures CRLF header injection vectors are filtered.
*
* Per RFC 7230, only VISIBLE ASCII characters, spaces, and horizontal
* tabs are allowed in values; only one whitespace character is allowed
* between visible characters.
*
* @see http://en.wikipedia.org/wiki/HTTP_response_splitting
*
* @param string $value
* @return string
*/
public static function filter($value)
{
$value = (string) $value;
$length = strlen($value);
$string = '';
for ($i = 0; $i < $length; $i += 1) {
$ascii = ord($value[$i]);
// Non-visible, non-whitespace characters
// 9 === horizontal tab
// 32-126, 128-254 === visible
// 127 === DEL
// 255 === null byte
if (
($ascii < 32 && $ascii !== 9)
|| $ascii === 127
|| $ascii > 254
) {
continue;
}
$string .= $value[$i];
}
return $string;
}
/**
* Validate a header value.
*
* Per RFC 7230, only VISIBLE ASCII characters, spaces, and horizontal
* tabs are allowed in values; only one whitespace character is allowed
* between visible characters.
*
* @see http://en.wikipedia.org/wiki/HTTP_response_splitting
*
* @param string $value
* @return bool
*/
public static function isValid($value)
{
$value = (string) $value;
$length = strlen($value);
for ($i = 0; $i < $length; $i += 1) {
$ascii = ord($value[$i]);
// Non-visible, non-whitespace characters
// 9 === horizontal tab
// 32-126, 128-254 === visible
// 127 === DEL
// 255 === null byte
if (
($ascii < 32 && $ascii !== 9)
|| $ascii === 127
|| $ascii > 254
) {
return false;
}
}
return true;
}
/**
* Assert a header value is valid.
*
* @param string $value
* @throws Exception\RuntimeException For invalid values.
* @return void
*/
public static function assertValid($value)
{
if (! self::isValid($value)) {
throw new Exception\InvalidArgumentException('Invalid header value');
}
}
}