From 05fd92660a268fb05ca05776d81fa68fcdfe7879 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Tim=20D=C3=BCsterhus?= <duesterhus@woltlab.com>
Date: Wed, 8 Apr 2020 14:47:30 +0200
Subject: [PATCH] Specify HTML.Doctype as HTML 4 Strict for HTML Purifier

Not setting a Doctype defaults to HTML 4 Transitional, allowing legacy
tags. HTML 4 Strict will attempt to convert them into a standards compliant
format.

HTML Purifier does not support the HTML 5 Doctype as a readily available
configuration.

Before:

    string '<p><font size="6">This is some text!</font></p>' (length=47)

After:

    string '<p><span style="font-size:xx-large;">This is some text!</span></p>' (length=66)
---
 .../system/html/input/filter/MessageHtmlInputFilter.class.php    | 1 +
 1 file changed, 1 insertion(+)

diff --git a/wcfsetup/install/files/lib/system/html/input/filter/MessageHtmlInputFilter.class.php b/wcfsetup/install/files/lib/system/html/input/filter/MessageHtmlInputFilter.class.php
index f8d6849798..a56d07032e 100644
--- a/wcfsetup/install/files/lib/system/html/input/filter/MessageHtmlInputFilter.class.php
+++ b/wcfsetup/install/files/lib/system/html/input/filter/MessageHtmlInputFilter.class.php
@@ -52,6 +52,7 @@ class MessageHtmlInputFilter implements IHtmlInputFilter {
 			
 			$config->set('CSS.AllowedProperties', ['color', 'font-family', 'font-size']);
 			$config->set('HTML.ForbiddenAttributes', ['*@lang', '*@xml:lang']);
+			$config->set('HTML.Doctype', 'HTML 4.01 Strict');
 			
 			$allowedSchemes = $config->get('URI.AllowedSchemes');
 			$allowedSchemes['ts3server'] = true;
-- 
2.20.1