vb.org Archive - Miscellaneous Hacks - Prevent APNG for users that are not allowed to have GIF images

This is a very small plugin.

We don't allow users to have GIF images. But users, clever as they are, started using APNG images instead (Animated Portable Network Graphics) which vBulletin sees as regular PNG images. Even though it only works on a couple of browsers (unsupported browsers only see the first frame), we found it created allot of confusion (other users wondering why they couldn't upload animated avatars, while other had them).

This is a small plugin that will prevent users from uploading APNG images. It's so small it isn't even worth to be made into a product. It only rejects the image if the user is not allowed to upload animated images.

I only tested it on vBulletin 3.8, but I'm pretty sure this works on most versions.

Please note: this will only prevent new APNG avatars from being uploaded.

I got the detection part from: http://foone.org/apng/.

I hope a few of you can use this :).

Installation
Go to your Administration Panel then:

1. Go to the 'Plugins & Products' menu
2. 'Add New plugin'
3. Values:

Product: vBulletin
Hook location: upload_accept
Title: Prevent APNG for users that are not allowed to have GIF images
Execution Order: 5 (doesn't really matter)
Plugin PHP Code:

PHP Code:


		
			
if(isset($this->allowanimation) AND $this->allowanimation === false)

{

    $img_bytes = @file_get_contents($this->upload['location']);



    if($img_bytes) 

    {

        if(strpos(substr($img_bytes, 0, strpos($img_bytes, 'IDAT')), 'acTL') !== false)

        {

            $this->set_error('upload_invalid_animatedgif');

            eval(standard_error($this->fetch_error()));

        }

    }

}

Plugin is Active: yes

4. Click 'Save'

X vBulletin 3.8.12 by vBS Debug Information
Template Usage: (1)ad_footer_end (1)ad_footer_start (1)ad_header_end (1)ad_header_logo (1)ad_navbar_below (1)bbcode_php_printable (1)footer (1)gobutton (1)header (1)headinclude (6)option (1)post_thanks_navbar_search (1)printthread (2)printthreadbit (1)spacer_close (1)spacer_open Phrase Groups Available: global postbit showthread	Included Files: ./printthread.php ./global.php ./includes/init.php ./includes/class_core.php ./includes/config.php ./includes/functions.php ./includes/class_hook.php ./includes/modsystem_functions.php ./includes/class_bbcode_alt.php ./includes/class_bbcode.php ./includes/functions_bigthree.php Hooks Called: init_startup init_startup_session_setup_start init_startup_session_setup_complete cache_permissions fetch_threadinfo_query fetch_threadinfo fetch_foruminfo style_fetch cache_templates global_start parse_templates global_setup_complete printthread_start bbcode_fetch_tags bbcode_create bbcode_parse_start bbcode_parse_complete_precache bbcode_parse_complete printthread_post printthread_complete
Messages:

X vBulletin 3.8.12 by vBS Debug Information

Page Generation 0.03372 seconds
Memory Usage 1,722KB
Queries Executed 10 (?)

More Information

Template Usage:

(1)ad_footer_end
(1)ad_footer_start
(1)ad_header_end
(1)ad_header_logo
(1)ad_navbar_below
(1)bbcode_php_printable
(1)footer
(1)gobutton
(1)header
(1)headinclude
(6)option
(1)post_thanks_navbar_search
(1)printthread
(2)printthreadbit
(1)spacer_close
(1)spacer_open

Phrase Groups Available:

global
postbit
showthread

Included Files:

./printthread.php
./global.php
./includes/init.php
./includes/class_core.php
./includes/config.php
./includes/functions.php
./includes/class_hook.php
./includes/modsystem_functions.php
./includes/class_bbcode_alt.php
./includes/class_bbcode.php
./includes/functions_bigthree.php

Hooks Called:

init_startup
init_startup_session_setup_start
init_startup_session_setup_complete
cache_permissions
fetch_threadinfo_query
fetch_threadinfo
fetch_foruminfo
style_fetch
cache_templates
global_start
parse_templates
global_setup_complete
printthread_start
bbcode_fetch_tags
bbcode_create
bbcode_parse_start
bbcode_parse_complete_precache
bbcode_parse_complete
printthread_post
printthread_complete

Messages:

X vBulletin 3.8.12 by vBS Debug Information
Page Generation 0.03372 seconds Memory Usage 1,722KB Queries Executed 10 (?)
More Information
Template Usage: (1)ad_footer_end (1)ad_footer_start (1)ad_header_end (1)ad_header_logo (1)ad_navbar_below (1)bbcode_php_printable (1)footer (1)gobutton (1)header (1)headinclude (6)option (1)post_thanks_navbar_search (1)printthread (2)printthreadbit (1)spacer_close (1)spacer_open Phrase Groups Available: global postbit showthread	Included Files: ./printthread.php ./global.php ./includes/init.php ./includes/class_core.php ./includes/config.php ./includes/functions.php ./includes/class_hook.php ./includes/modsystem_functions.php ./includes/class_bbcode_alt.php ./includes/class_bbcode.php ./includes/functions_bigthree.php Hooks Called: init_startup init_startup_session_setup_start init_startup_session_setup_complete cache_permissions fetch_threadinfo_query fetch_threadinfo fetch_foruminfo style_fetch cache_templates global_start parse_templates global_setup_complete printthread_start bbcode_fetch_tags bbcode_create bbcode_parse_start bbcode_parse_complete_precache bbcode_parse_complete printthread_post printthread_complete
Messages: