mb_encode_mimeheader

Anonymous (2009-04-11 18:19:35)

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;
}
?>

tokul at users dot sourceforge dot net (2008-03-30 04:26:36)

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

chappy at citromail dot hu (2006-06-05 04:33:59)

I found a bad function. 

<?php
function encodeHeader($input, $charset = 'ISO-8859-2')
{
    preg_match_all('/(\\w*[\\x80-\\xFF]+\\w*)/', $input, $matches);
    foreach ($matches[1] as $value) {
        $replacement = preg_replace('/([\\x80-\\xFF])/e', '"=" . strtoupper(dechex(ord("\\1")))', $value);
        $input = str_replace($value, '=?' . $charset . '?Q?' . $replacement . '?=', $input);
    }
    return $input;
}
?>

This function should be used:

<?php
function encodeHeader($input, $charset = 'ISO-8859-2')
{
    $m=preg_match_all('/(\w*[\x80-\xFF]+\w*)/', $input, $matches);
    if($m)$input=mb_encode_mimeheader($input,$charset, 'Q');
    return $input;
}
?>

stormflyCUT at hyh dot pl (2006-05-05 04:41:46)

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').

paravoid (2006-01-01 17:58:23)

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;
}

nigrez at nius dot waw dot pl (2005-12-13 15:42:26)

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;
}

?>

gullevek at gullevek dot org (2005-11-06 17:29:18)

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;
}

?>

chappy at citromail dot hu (2005-10-28 23:14:36)

iwakura at junx dot org (2005-09-15 23:35:15)

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

mortoray at ecircle-ag dot com (2005-03-15 01:19:59)

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

gullevek at gullevek dot org (2003-07-30 00:02:10)

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

masataka (2003-04-12 07:46:20)

second parameter 'charset' is character encoding name, but default must be UTF-8 on PHP4.3.1.