Proper way to decode incoming email subject (utf 8) - php

Question

I'm trying to pipe my incoming mails to a PHP script so I can store them in a database and other things. I'm using the class MIME E-mail message parser (registration required) although I don't think that's important.
I have a problem with email subjects. It works fine when the title is in English but if the subject uses non-latin Characters I get something like
=?UTF-8?B?2KLYstmF2KfbjNi0?=
for a title like
یک دو سه
I decode the subject like this:
$subject = str_replace('=?UTF-8?B?' , '' , $subject);
$subject = str_replace('?=' , '' , $subject);
$subject = base64_decode($subject);
It works fine with short subjects with like 10-15 characters but with a longer title I get half of the original title with something like ��� at the end.
If the title is even longer, like 30 characters, I get nothing. Am I doing this right?

Answer 1

You can use the mb_decode_mimeheader() function to decode your string.

Answer 2

Despite the fact that this is almost a year old - I found this and am facing a similar problem.
I'm unsure why you're getting odd characters, but perhaps you are trying to display them somewhere your charset is unsupported.
Here's some code I wrote which should handle everything except the charset conversion, which is a large problem that many libraries handle much better. (PHP's MB library, for instance)
class mail {
/**
* If you change one of these, please check the other for fixes as well
*
* #const Pattern to match RFC 2047 charset encodings in mail headers
*/
const rfc2047header = '/=\?([^ ?]+)\?([BQbq])\?([^ ?]+)\?=/';
const rfc2047header_spaces = '/(=\?[^ ?]+\?[BQbq]\?[^ ?]+\?=)\s+(=\?[^ ?]+\?[BQbq]\?[^ ?]+\?=)/';
/**
* http://www.rfc-archive.org/getrfc.php?rfc=2047
*
* =?<charset>?<encoding>?<data>?=
*
* #param string $header
*/
public static function is_encoded_header($header) {
// e.g. =?utf-8?q?Re=3a=20Support=3a=204D09EE9A=20=2d=20Re=3a=20Support=3a=204D078032=20=2d=20Wordpress=20Plugin?=
// e.g. =?utf-8?q?Wordpress=20Plugin?=
return preg_match(self::rfc2047header, $header) !== 0;
}
public static function header_charsets($header) {
$matches = null;
if (!preg_match_all(self::rfc2047header, $header, $matches, PREG_PATTERN_ORDER)) {
return array();
}
return array_map('strtoupper', $matches[1]);
}
public static function decode_header($header) {
$matches = null;
/* Repair instances where two encodings are together and separated by a space (strip the spaces) */
$header = preg_replace(self::rfc2047header_spaces, "$1$2", $header);
/* Now see if any encodings exist and match them */
if (!preg_match_all(self::rfc2047header, $header, $matches, PREG_SET_ORDER)) {
return $header;
}
foreach ($matches as $header_match) {
list($match, $charset, $encoding, $data) = $header_match;
$encoding = strtoupper($encoding);
switch ($encoding) {
case 'B':
$data = base64_decode($data);
break;
case 'Q':
$data = quoted_printable_decode(str_replace("_", " ", $data));
break;
default:
throw new Exception("preg_match_all is busted: didn't find B or Q in encoding $header");
}
// This part needs to handle every charset
switch (strtoupper($charset)) {
case "UTF-8":
break;
default:
/* Here's where you should handle other character sets! */
throw new Exception("Unknown charset in header - time to write some code.");
}
$header = str_replace($match, $data, $header);
}
return $header;
}
}
When run through a script and displayed in a browser using UTF-8, the result is:
آزمایش
You would run it like so:
$decoded = mail::decode_header("=?UTF-8?B?2KLYstmF2KfbjNi0?=");

Answer 3

Use php native function
<?php
mb_decode_mimeheader($text);
?>
This function can handle utf8 as well as iso-8859-1 string.
I have tested it.

Answer 4

Use php function:
<?php
imap_utf8($text);
?>

Answer 5

Just to add yet one more way to do this (or if you don't have the mbstring extension installed but do have iconv):
iconv_mime_decode($str, ICONV_MIME_DECODE_CONTINUE_ON_ERROR, 'UTF-8')

Answer 6

Would the imap-mime-header-decode function help here?
Found myself in a similar situation today.
http://www.php.net/manual/en/function.imap-mime-header-decode.php