Viewing file:  HeaderSecurity.php (4.65 KB) -rw-r--r--
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<?php
declare(strict_types=1);
namespace Laminas\Diactoros;
use function get_debug_type;
use function in_array;
use function is_numeric;
use function is_string;
use function ord;
use function preg_match;
use function sprintf;
use function strlen;
/**
* Provide security tools around HTTP headers to prevent common injection vectors.
*/
final class HeaderSecurity
{
/**
* Private constructor; non-instantiable.
*
* @codeCoverageIgnore
*/
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; header continuations MUST consist of
* a single CRLF sequence followed by a space or horizontal tab.
*
* This method filters any values not allowed from the string, and is
* lossy.
*
* @see http://en.wikipedia.org/wiki/HTTP_response_splitting
*/
public static function filter(string $value): string
{
$length = strlen($value);
$string = '';
for ($i = 0; $i < $length; $i += 1) {
$ascii = ord($value[$i]);
// Detect continuation sequences
if ($ascii === 13) {
$lf = ord($value[$i + 1]);
$ws = ord($value[$i + 2]);
if ($lf === 10 && in_array($ws, [9, 32], true)) {
$string .= $value[$i] . $value[$i + 1];
$i += 1;
}
continue;
}
// Non-visible, non-whitespace characters
// 9 === horizontal tab
// 32-126, 128-254 === visible
// 127 === DEL
// 255 === null byte
if (
($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; header continuations MUST consist of
* a single CRLF sequence followed by a space or horizontal tab.
*
* @see http://en.wikipedia.org/wiki/HTTP_response_splitting
*
* @param string|int|float $value
*/
public static function isValid($value): bool
{
$value = (string) $value;
// Look for:
// \n not preceded by \r, OR
// \r not followed by \n, OR
// \r\n not followed by space or horizontal tab; these are all CRLF attacks
if (preg_match("#(?:(?:(?<!\r)\n)|(?:\r(?!\n))|(?:\r\n(?![ \t])))#", $value)) {
return false;
}
// Non-visible, non-whitespace characters
// 9 === horizontal tab
// 10 === line feed
// 13 === carriage return
// 32-126, 128-254 === visible
// 127 === DEL (disallowed)
// 255 === null byte (disallowed)
if (preg_match('/[^\x09\x0a\x0d\x20-\x7E\x80-\xFE]/', $value)) {
return false;
}
return true;
}
/**
* Assert a header value is valid.
*
* @param mixed $value Value to be tested. This method asserts it is a string or number.
* @throws Exception\InvalidArgumentException For invalid values.
*/
public static function assertValid(mixed $value): void
{
if (! is_string($value) && ! is_numeric($value)) {
throw new Exception\InvalidArgumentException(sprintf(
'Invalid header value type; must be a string or numeric; received %s',
get_debug_type($value)
));
}
if (! self::isValid($value)) {
throw new Exception\InvalidArgumentException(sprintf(
'"%s" is not valid header value',
$value
));
}
}
/**
* Assert whether or not a header name is valid.
*
* @see http://tools.ietf.org/html/rfc7230#section-3.2
*
* @throws Exception\InvalidArgumentException
*/
public static function assertValidName(mixed $name): void
{
if (! is_string($name)) {
throw new Exception\InvalidArgumentException(sprintf(
'Invalid header name type; expected string; received %s',
get_debug_type($name)
));
}
if (! preg_match('/^[a-zA-Z0-9\'`#$%&*+.^_|~!-]+$/D', $name)) {
throw new Exception\InvalidArgumentException(sprintf(
'"%s" is not valid header name',
$name
));
}
}
}
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