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Bug #60494 iconv_mime_decode does ignore special characters
Submitted: 2011-12-11 21:12 UTC Modified: 2018-11-13 22:31 UTC
From: bin at webcandy dot at Assigned: cmb (profile)
Status: Closed Package: ICONV related
PHP Version: Irrelevant OS: Windows 7
Private report: No CVE-ID: None
View Developer Edit
 [2011-12-11 21:12 UTC] bin at webcandy dot at 
Description:
------------
If the string $text passed to iconv_mime_decode($text) does contain special characters (tested with ä, ü and ß), it will just return an empty character for these characters.

In my opinion it iconv_mime_decode should leave special characters as they are as long as they're not encoded via Q-encoding.

Tested on Windows 7 and Debian.

iconv.output_encoding is set to "UTF-8"

Test script:
---------------
<?php

var_dump(iconv_mime_decode('ä'));
var_dump(iconv_mime_decode('ö'));
var_dump(iconv_mime_decode('ß'));

?>

Expected result:
----------------
string(1) "ä"
string(1) "ö"
string(1) "ß"

Actual result:
--------------
string(0) ""
string(0) ""
string(0) ""

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 [2011-12-11 21:16 UTC] bin at webcandy dot at 
Expected result should probably have 2 bytes as I expect it to be UTF-8 when using iconv.output_encoding = UTF-8

Exptected result:
----------------
string(2) "ä"
string(2) "ö"
string(2) "ß"
 [2018-03-11 23:12 UTC] [email protected]
-Status: Open +Status: Verified
 [2018-03-11 23:12 UTC] [email protected] 
iconv_mime_decode() is supposed to decode a MIME header according
to RFC 2047. Neither 'ä', 'ö' nor 'ß' are valid characters in
headers, so returning these characters unmodified would be wrong.

However, it is not correct to simply skip invalid characters.
Instead the function should fail (i.e. return FALSE).  It seems
the problem is that inside of _php_iconv_mime_decode() all calls
to _php_iconv_appendc() ignore its return value (although all
calls to _php_iconv_appendl() cater to it).  In this case the
culprit is:
<https://github.com/php/php-src/blob/php-7.2.3/ext/iconv/iconv.c#L1538>
 [2018-08-25 15:38 UTC] [email protected]
-Assigned To: +Assigned To: cmb
 [2018-08-25 15:54 UTC] [email protected] 
Automatic comment on behalf of [email protected]
Revision: http://git.php.net/?p=php-src.git;a=commit;h=e29c946c29afdb0bf89c5329fcf3038448d50e17
Log: Fix #60494: iconv_mime_decode does ignore special characters
 [2018-08-25 15:54 UTC] [email protected]
-Status: Verified +Status: Closed
 [2018-11-13 22:17 UTC] shafer_w2002 at yahoo dot com 
This fix has now broken all headers even with the ICONV_MIME_DECODE_CONTINUE_ON_ERROR flag set.   When this flag is set it should continue anyway.
 [2018-11-13 22:31 UTC] [email protected] 
> This fix has now broken all headers even with the
> ICONV_MIME_DECODE_CONTINUE_ON_ERROR flag set.   When this flag is
> set it should continue anyway.

Thanks for reporting!  Tentatively, I agree with your statement.
However, since this fix has already been shipped with PHP 7.1.22
and 7.2.10, please open a new ticket (and assign to me, if
possible) to better be able to track the bug(fixe)s.
 
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