Fixed php 8 + unfurl - mb_convert_encoding can throw ValueError

X

Xon

Well-known member
Affected version
2.2.6 Patch 2
On fetching https://www.toei-anim.co.jp:443/tv/digimon_t/chara/dukemon.html

A ValueError is thrown and the unfurl is not marked as failed.
Code: 
ValueError: mb_convert_encoding(): Argument #3 ($from_encoding) contains invalid encoding "none" src/XF/Http/Metadata.php:200
Generated by: Unknown account Sep 9, 2021 at 10:47 PM
Stack trace
#0 src/XF/Http/Metadata.php(200): mb_convert_encoding('<html>
<head>
<...', 'utf-8', 'none')
#1 src/XF/Http/Metadata.php(35): XF\Http\Metadata->convertBodyCharset()
#2 src/XF/Http/MetadataFetcher.php(129): XF\Http\Metadata->__construct(Object(XF\Pub\App), '<html>
<head>
<...', Array, 'http://www.toei...')
#3 src/XF/Service/Unfurl/Fetcher.php(22): XF\Http\MetadataFetcher->fetch('http://www.toei...', NULL)
#4 unfurl.php(57): XF\Service\Unfurl\Fetcher->fetch()
#5 {main}

The URL returns the following headers;
Code: 
HTTP/1.1 200 OK
Date: Thu, 09 Sep 2021 15:57:05 GMT
Content-Type: text/html; charset=none
Content-Length: 4982
Connection: keep-alive
Server: Apache
Last-Modified: Mon, 18 Nov 2013 07:27:01 GMT
ETag: "1376-4eb6e794f1b40"
Accept-Ranges: bytes

Content-Type: text/html; charset=none makes php 8 sad.
 
Before php 7.4, the unfurl would fail and it would just render as the title "LN^[" which isn't really correct either. But at least it didn't cause an error
 
Xon said:
Content-Type: text/html; charset=none makes php 8 sad.
Click to expand...
Me too :(

Ironically the meta tag in the HTML output has it as Shift_JIS and that would be a valid encoding. Though somewhat annoyingly if we checked that against mb_list_encodings then it wouldn't be found. Which is my current approach to protecting against this error so this may not be fixable for this site.

Alternative would be to do a try and catch the ValueError but then we have to have a different code path for PHP 8.

Final alternative would be to bail out entirely if it's an unknown charset but as I just pointed out Shift_JIS is supported, it just isn't listed. That would turn it into a basic link at least.

SAD
 
Thank you for reporting this issue, it has now been resolved. We are aiming to include any changes that have been made in a future XF release (2.2.7).

Change log:
When fetching metadata from a URL improve checks to ensure we get a valid charset encoding where possible and prevent against an Error exception thrown if an invalid character set encoding is encountered.
Click to expand...
There may be a delay before changes are rolled out to the XenForo Community.
 

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