mb_encode_mimeheader

(PHP 4 >= 4.0.6, PHP 5, PHP 7, PHP 8)

mb_encode_mimeheader — Codifica un string para la cabecera MIME

Descripción

mb_encode_mimeheader(
    string $str,
    string $charset = determined by mb_language(),
    string $transfer_encoding = "B",
    string $linefeed = "\r\n",
    int $indent = 0
): string

Codifica el string str dado mediante el esquema de codificación de cabecera MIME.

Parámetros

str: El string que va a ser codificado. Su codificación debería ser la misma que mb_internal_encoding().
charset: charset especifica el nombre del conjunto de caracteres en el cual está representado str. El valor predeterminado está determinado por el ajuste NLS en uso (mbstring.language).
transfer_encoding: transfer_encoding especifica el esquema de la codifición MIME. Debería ser "B" (Base64) o "Q" (Quoted-Printable). Si no ser proporciona será "B".
linefeed: linefeed especifica la marca EOL (fin de línea) con la que mb_encode_mimeheader() realiza el pliegue de línea (un término de » RFC, que es el acto de dividir una línea mayor que una cierta longitud en varias líneas. La longitud actualmente es de 74 caracteres). Si no se proporciona será "\r\n" (CRLF).
indent: La indentación de la primera línea (número de caracteres en la cabecera antes de str).

Valores devueltos

Una versión convertida del string representado en ASCII.

Ejemplos

Ejemplo #1 Ejemplo de mb_encode_mimeheader()

<?php
$name = ""; // kanji
$mbox = "kru";
$doma = "gtinn.mon";
$addr = mb_encode_mimeheader($name, "UTF-7", "Q") . " <" . $mbox . "@" . $doma . ">";
echo $addr;
?>

Notas

Nota:
Esta función no está diseñada para dividir líneas en puntos de rotura contextual de alto nivel (límites de palabras, etc.). Este comportamiento podría abarrotar el string original con espacios inesperados.

Ver también

mb_decode_mimeheader() - Decodifica un string en el campo de cabecera MIME

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User Contributed Notes 10 notes

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stormflyCUT at hyh dot pl ¶

18 years ago


Some solution for using national chars and have problem with UTF-8 for example in mail subject. Before you use mb_encode_mimeheader with UTF-8 set mb_internal_encoding('UTF-8').

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nigrez at nius dot waw dot pl ¶

19 years ago


True, function is broken (PHP5.1, encoding from UTF-8 with pl_PL charset). Below is about 15% faster version of proposed _mb_mime_encode. Also it has header more like othe mb_* functions and doesn't trigger any errors/warnings/notices.

<?php

function mb_mime_header($string, $encoding=null, $linefeed="\r\n") {
  if(!$encoding) $encoding = mb_internal_encoding();
  $encoded = '';

  while($length = mb_strlen($string)) {
    $encoded .= "=?$encoding?B?"
             . base64_encode(mb_substr($string,0,24,$encoding))
             . "?=$linefeed";

    $string = mb_substr($string,24,$length,$encoding);
  }

  return $encoded;
}

?>

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gullevek at gullevek dot org ¶

21 years ago


Read this FIRST: http://bugs.php.net/bug.php?id=23192 because mb_encode_mimeheaders is BUGGY!

a work around for the multibyte broken error for too long subjects for ISO-2022-JP:

$pos=0;
$split=36; // after 36 single bytes characters, if then comes MB, it is broken
while ($pos<mb_strlen($string,$encoding))
{
  $output=mb_strimwidth($string,$pos,$split,"",$encoding);
  $pos+=mb_strlen($output,$encoding);
  $_string.=(($_string)?' ':'').mb_encode_mimeheader($output,$encoding);
}
$string=$_string;

is not the best, but it works

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Anonymous ¶

15 years ago


I could not find a PHP function to MIME encode the name for a n email address.



Input   = "Karl Müller<kmueller@gmx.de>"

Output = "Karl%20M%FCller<kmueller@gmx.de>"



I wrote it on my own:



<?php

// required to encode names in email addresses    

// replace " " with "%20"

// replace "ü" with "%FC" 

// replace "%" with "%25"      etc....

// Use "%" as Delimiter for MIME

// Use "=" as Delimiter for Quoted Printable

// Input string must be UTF8 encoded

public static function EncodeMime($Text, $Delimiter)

{

    $Text = utf8_decode($Text);

    $Len  = strlen($Text);

    $Out  = "";

    for ($i=0; $i<$Len; $i++)

    {

        $Chr = substr($Text, $i, 1);

        $Asc = ord($Chr);



        if ($Asc > 0x255) // Unicode not allowed

        {

            $Out .= "?";

        }

        else if ($Chr == " " || $Chr == $Delimiter || $Asc > 127) 

        {

            $Out .= $Delimiter . strtoupper(bin2hex($Chr));

        }

        else $Out .= $Chr;

    }

    return $Out;

}

?>

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tokul at users dot sourceforge dot net ¶

16 years ago


mb_encode_mimeheader() depends on correct mbstring.internal_encoding setting. It tries to convert $str from internal encoding to $charset. If you ignore mbstring internal encoding, function might encode strings incorrectly even when $str character set matches $charset

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gullevek at gullevek dot org ¶

19 years ago


My first post was around 2003, and still the mb_mime_header is broken. It is *NOT* usable with longer subjects, and mostly unusable with anything else than japanese.

iwakura at junx dot org is also not working for me, it produces also some gargabe.

I updated my old function (the one I posted 2003) and I tested it with overlong subjects in UTF-8, ISO-2022-JP (japanese), GB2312 (simplified chinese) and EUC-KR (korean) and I got readable results in thunderbird, mail.app, outlook, etc.

<?php

function _mb_mime_encode($string, $encoding)
{
    $pos = 0;
    // after 36 single bytes characters if then comes MB, it is broken
    // but I trimmed it down to 24, to stay 100% < 76 chars per line
    $split = 24;
    while ($pos < mb_strlen($string, $encoding))
    {
        $output = mb_strimwidth($string, $pos, $split, "", $encoding);
        $pos += mb_strlen($output, $encoding);
        $_string_encoded = "=?".$encoding."?B?".base64_encode($output)."?=";
        if ($_string)
            $_string .= "\r\n";
        $_string .= $_string_encoded;
    }
    $string = $_string;
    return $string;
}

?>

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paravoid ¶

18 years ago


If mb_ version doesn't work for you in MIME-B mode:

function encode_mimeheader($string, $charset=null, $linefeed="\r\n") {
    if (!$charset)
        $charset = mb_internal_encoding();

    $start = "=?$charset?B?";
    $end = "?=";
    $encoded = '';

    /* Each line must have length <= 75, including $start and $end */
    $length = 75 - strlen($start) - strlen($end);
    /* Average multi-byte ratio */
    $ratio = mb_strlen($string, $charset) / strlen($string);
    /* Base64 has a 4:3 ratio */
    $magic = $avglength = floor(3 * $length * $ratio / 4);

    for ($i=0; $i <= mb_strlen($string, $charset); $i+=$magic) {
        $magic = $avglength;
        $offset = 0;
        /* Recalculate magic for each line to be 100% sure */
        do {
            $magic -= $offset;
            $chunk = mb_substr($string, $i, $magic, $charset);
            $chunk = base64_encode($chunk);
            $offset++;
        } while (strlen($chunk) > $length);
        if ($chunk)
            $encoded .= ' '.$start.$chunk.$end.$linefeed;
    }
    /* Chomp the first space and the last linefeed */
    $encoded = substr($encoded, 1, -strlen($linefeed));

    return $encoded;
}

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chappy at citromail dot hu ¶

19 years ago


In countries where there's non-us ASCII, it's a very good example, for sending mail:

mb_internal_encoding('iso-8859-2');
setlocale(LC_CTYPE, 'hu_HU');

function encode($str,$charset){
    $str=mb_encode_mimeheader(trim($str),$charset, 'Q', "\n\t");
    return $str;
}

print encode('the text with spec. chars: &#337; &#368; &#336; &#369;, ?','iso-8859-2');

It creates a 7bit string

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-1

iwakura at junx dot org ¶

19 years ago


i think mb_encode_mimeheader still have bug. here is sample code:

function mb_encode_mimeheader2($string, $encoding = "ISO-2022-JP") {
    $string_array = array();
    $pos = 0;
    $row = 0;
    $mode = 0;
    
    while ($pos < mb_strlen($string)) {
        $word = mb_strimwidth($string, $pos, 1);
        if (!$word) {
            $word = mb_strimwidth($string, $pos, 2);
        }
        if (mb_ereg_match("[ -~]", $word)) {    // ascii
            if ($mode != 1) {
                $row++;
                $mode = 1;
                $string_array[$row] = NULL;
            }
        } else {                                // multibyte
            if ($mode != 2) {
                $row++;
                $mode = 2;
                $string_array[$row] = NULL;
            }
        }
        $string_array[$row] .= $word;
        $pos++;
    }
    
    //echo "<pre>";
    //print_r($string_array);
    //echo "</pre>";
    
    foreach ($string_array as $key => $value) {
        $value = mb_convert_encoding($value, $encoding);
        $string_array[$key] = mb_encode_mimeheader($value, $encoding);
    }
    
    //echo "<pre>";
    //print_r($string_array);
    //echo "</pre>";
    
    return implode("", $string_array);
}

is not the best, but it works

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-3

mortoray at ecircle-ag dot com ¶

19 years ago


At least for Q encoding, this function is unsafe and does not encode correctly. Raw characters which appear as RFC2047 sequences are simply left as is.

Ex:

mb_encode_mimeheader( '=?iso-8859-1?q?this=20is=20some=20text?=' );

returns '=?iso-8859-1?q?this=20is=20some=20text?='

The exact same string, which is obviously not the encoding for the source string.  That is, mb_encode_mimeheader does not do any type of escaping.

That is, the following condition is not always true:
    mb_decode_mimeheader( mb_encode_mimeheader( $text ) ) == $text

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