mb_decode_mimeheader - PHP code example

php Function Mb_Decode_Mimeheader

Article about php function mb_decode_mimeheader:

The inbuilt mb_decode_mimeheader() decodes encoded-word string str in MIME header. It returns the decoded string in internal character encoding.

MIME (Multipurpose Internet Mail Extensions) defines a set of rules for the encoding of text within email messages. For example, it allows you to include non-ASCII text in some of the header fields such as From, To, Cc and Bcc, as well as the subject line.

In order to send such messages, the email client must be able to read the MIME content. This means that the header field must be encoded using one of the schemes defined in RFC 2047. The most common ones are B'' (Base64) and Q'' (Quoted-Printable).

To encode the header field, you can use mb_encode_mimeheader(). The function takes two parameters, charset and transfer-encoding. charset specifies the character encoding name. The default value is ISO-2022-JP. The transfer-encoding should be either B'' (Base64) or Q'' (Quoted-Printable). The latter can be used only if the mb_decode_mimeheader() function is enabled and the email client supports the Q encoding.

It is possible to skip the mb_decode_mimeheader() and directly use the encode_header() function, if a multibyte character set is supported by mbstring (e.g., utf-8). However, this approach is less convenient because it does not support the Q encoding, and it can cause E_USER_NOTICE errors in some cases (see FAQ entry below). If you use the latter option, you should set the mbstring.internal_encoding variable to the same value as the charset specified in your mb_decode_mimeheader() call.

mb_decode_mimeheader example

use Symfony\Polyfill\Mbstring as p;

if (!function_exists('mb_convert_encoding')) {
    function mb_convert_encoding(array|string|null $string, ?string $to_encoding, array|string|null $from_encoding = null): array|string|false { return p\Mbstring::mb_convert_encoding($string ?? '', (string) $to_encoding, $from_encoding); }
}
if (!function_exists('mb_decode_mimeheader')) {
    function mb_decode_mimeheader(?string $string): string { return p\Mbstring::mb_decode_mimeheader((string) $string); }
}
if (!function_exists('mb_encode_mimeheader')) {
    function mb_encode_mimeheader(?string $string, ?string $charset = null, ?string $transfer_encoding = null, ?string $newline = "\r\n", ?int $indent = 0): string { return p\Mbstring::mb_encode_mimeheader((string) $string, $charset, $transfer_encoding, (string) $newline, (int) $indent); }
}
if (!function_exists('mb_decode_numericentity')) {
    function mb_decode_numericentity(?string $string, array $map, ?string $encoding = null): string { return p\Mbstring::mb_decode_numericentity((string) $string, $map, $encoding); }
}
if (!function_exists('mb_encode_numericentity')) {
    function mb_encode_numericentity(?string $string, array $map, ?string $encoding = null, ?bool $hex = false): string { return p\Mbstring::mb_encode_numericentity((string) $string, $map, $encoding, (bool) $hex); }
}
if (!function_exists('mb_convert_case')) {

    if (!function_exists('iconv_strpos')) {
        function iconv_strpos(?string $haystack, ?string $needle, ?int $offset = 0, ?string $encoding = null): int|false { null === $encoding && $encoding = p\Iconv::$internalEncoding; return mb_strpos((string) $haystack, (string) $needle, (int) $offset, $encoding); }
    }
    if (!function_exists('iconv_strrpos')) {
        function iconv_strrpos(?string $haystack, ?string $needle, ?string $encoding = null): int|false { null === $encoding && $encoding = p\Iconv::$internalEncoding; return mb_strrpos((string) $haystack, (string) $needle, 0, $encoding); }
    }
    if (!function_exists('iconv_substr')) {
        function iconv_substr(?string $string, ?int $offset, ?int $length = null, ?string $encoding = null): string|false { null === $encoding && $encoding = p\Iconv::$internalEncoding; return mb_substr((string) $string, (int) $offset, $length, $encoding); }
    }
    if (!function_exists('iconv_mime_decode')) {
        function iconv_mime_decode($string, $mode = 0, $encoding = null) { $currentMbEncoding = mb_internal_encoding(); null === $encoding && $encoding = p\Iconv::$internalEncoding; mb_internal_encoding($encoding); $decoded = mb_decode_mimeheader($string); mb_internal_encoding($currentMbEncoding); return $decoded; }
    }
} else {
    if (!function_exists('iconv_strlen')) {
        if (extension_loaded('xml')) {
            function iconv_strlen(?string $string, ?string $encoding = null): int|false { return p\Iconv::strlen1((string) $string, $encoding); }
        } else {
            function iconv_strlen(?string $string, ?string $encoding = null): int|false { return p\Iconv::strlen2((string) $string, $encoding); }
        }
    }

    if (!function_exists('iconv_strpos')) {

    if (!function_exists('iconv_strpos')) {
        function iconv_strpos($haystack, $needle, $offset = 0, $encoding = null) { null === $encoding && $encoding = p\Iconv::$internalEncoding; return mb_strpos($haystack, $needle, $offset, $encoding); }
    }
    if (!function_exists('iconv_strrpos')) {
        function iconv_strrpos($haystack, $needle, $encoding = null) { null === $encoding && $encoding = p\Iconv::$internalEncoding; return mb_strrpos($haystack, $needle, 0, $encoding); }
    }
    if (!function_exists('iconv_substr')) {
        function iconv_substr($string, $offset, $length = 2147483647, $encoding = null) { null === $encoding && $encoding = p\Iconv::$internalEncoding; return mb_substr($string, $offset, $length, $encoding); }
    }
    if (!function_exists('iconv_mime_decode')) {
        function iconv_mime_decode($string, $mode = 0, $encoding = null) { $currentMbEncoding = mb_internal_encoding(); null === $encoding && $encoding = p\Iconv::$internalEncoding; mb_internal_encoding($encoding); $decoded = mb_decode_mimeheader($string); mb_internal_encoding($currentMbEncoding); return $decoded; }
    }
} else {
    if (!function_exists('iconv_strlen')) {
        if (extension_loaded('xml')) {
            function iconv_strlen($string, $encoding = null) { return p\Iconv::strlen1($string, $encoding); }
        } else {
            function iconv_strlen($string, $encoding = null) { return p\Iconv::strlen2($string, $encoding); }
        }
    }

    if (!function_exists('iconv_strpos')) {

                    if (
                        property_exists($address, 'personal') &&
                        //Check for a Mbstring constant rather than using extension_loaded, which is sometimes disabled                         defined('MB_CASE_UPPER') &&
                        preg_match('/^=\?.*\?=$/s', $address->personal)
                    ) {
                        $origCharset = mb_internal_encoding();
                        mb_internal_encoding($charset);
                        //Undo any RFC2047-encoded spaces-as-underscores                         $address->personal = str_replace('_', '=20', $address->personal);
                        //Decode the name                         $address->personal = mb_decode_mimeheader($address->personal);
                        mb_internal_encoding($origCharset);
                    }

                    $addresses[] = [
                        'name' => (property_exists($address, 'personal') ? $address->personal : ''),
                        'address' => $address->mailbox . '@' . $address->host,
                    ];
                }
            }
        } else {
            //Use this simpler parser

use Symfony\Polyfill\Mbstring as p;

if (\PHP_VERSION_ID >= 80000) {
    return require __DIR__.'/bootstrap80.php';
}

if (!function_exists('mb_convert_encoding')) {
    function mb_convert_encoding($string, $to_encoding, $from_encoding = null) { return p\Mbstring::mb_convert_encoding($string, $to_encoding, $from_encoding); }
}
if (!function_exists('mb_decode_mimeheader')) {
    function mb_decode_mimeheader($string) { return p\Mbstring::mb_decode_mimeheader($string); }
}
if (!function_exists('mb_encode_mimeheader')) {
    function mb_encode_mimeheader($string, $charset = null, $transfer_encoding = null, $newline = "\r\n", $indent = 0) { return p\Mbstring::mb_encode_mimeheader($string, $charset, $transfer_encoding, $newline, $indent); }
}
if (!function_exists('mb_decode_numericentity')) {
    function mb_decode_numericentity($string, $map, $encoding = null) { return p\Mbstring::mb_decode_numericentity($string, $map, $encoding); }
}
if (!function_exists('mb_encode_numericentity')) {
    function mb_encode_numericentity($string, $map, $encoding = null, $hex = false) { return p\Mbstring::mb_encode_numericentity($string, $map, $encoding, $hex); }
}
if (!function_exists('mb_convert_case')) {