<?php
/**
* @see https://github.com/laminas/laminas-mail for the canonical source repository
* @copyright https://github.com/laminas/laminas-mail/blob/master/COPYRIGHT.md
* @license https://github.com/laminas/laminas-mail/blob/master/LICENSE.md New BSD License
*/
namespace Laminas\Mail\Header;
final class HeaderValue
{
/**
* No public constructor.
*/
private function __construct()
{
}
/**
* Filter the header value according to RFC 2822
*
* @see http://www.rfc-base.org/txt/rfc-2822.txt (section 2.2)
* @param string $value
* @return string
*/
public static function filter($value)
{
$result = '';
$total = strlen($value);
// Filter for CR and LF characters, leaving CRLF + WSP sequences for
// Long Header Fields (section 2.2.3 of RFC 2822)
for ($i = 0; $i < $total; $i += 1) {
$ord = ord($value[$i]);
if ($ord === 10 || $ord > 127) {
continue;
}
if ($ord === 13) {
if ($i + 2 >= $total) {
continue;
}
$lf = ord($value[$i + 1]);
$sp = ord($value[$i + 2]);
if ($lf !== 10 || $sp !== 32) {
continue;
}
$result .= "\r\n ";
$i += 2;
continue;
}
$result .= $value[$i];
}
return $result;
}
/**
* Determine if the header value contains any invalid characters.
*
* @see http://www.rfc-base.org/txt/rfc-2822.txt (section 2.2)
* @param string $value
* @return bool
*/
public static function isValid($value)
{
$total = strlen($value);
for ($i = 0; $i < $total; $i += 1) {
$ord = ord($value[$i]);
// bare LF means we aren't valid
if ($ord === 10 || $ord > 127) {
return false;
}
if ($ord === 13) {
if ($i + 2 >= $total) {
return false;
}
$lf = ord($value[$i + 1]);
$sp = ord($value[$i + 2]);
if ($lf !== 10 || ! in_array($sp, [9, 32], true)) {
return false;
}
// skip over the LF following this
$i += 2;
}
}
return true;
}
/**
* Assert that the header value is valid.
*
* Raises an exception if invalid.
*
* @param string $value
* @throws Exception\RuntimeException
* @return void
*/
public static function assertValid($value)
{
if (! self::isValid($value)) {
throw new Exception\RuntimeException('Invalid header value detected');
}
}
}