From 8b73fa9113b3a9ba6241b930373f1e2d7f668163 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Tim=20D=C3=BCsterhus?= <duesterhus@woltlab.com>
Date: Thu, 28 Jan 2021 09:51:10 +0100
Subject: [PATCH] Remove the `blacklist_hostnames` option

The hostname blocklist requires a PTR lookup for every single request. This is
slow and unreliable.

see #3909
---
 com.woltlab.wcf/option.xml                      |  5 +----
 constants.php                                   |  1 -
 wcfsetup/install/files/lib/system/WCF.class.php | 17 +++++------------
 wcfsetup/install/files/options.inc.php          |  1 -
 wcfsetup/install/lang/de.xml                    |  2 --
 wcfsetup/install/lang/en.xml                    |  2 --
 6 files changed, 6 insertions(+), 22 deletions(-)

diff --git a/com.woltlab.wcf/option.xml b/com.woltlab.wcf/option.xml
index cd347cefe2..8c4d12f4a0 100644
--- a/com.woltlab.wcf/option.xml
+++ b/com.woltlab.wcf/option.xml
@@ -722,10 +722,6 @@ block:wcf.acp.option.blacklist_sfs_action.block]]></selectoptions>
 				<categoryname>security.blacklist.custom</categoryname>
 				<optiontype>textarea</optiontype>
 			</option>
-			<option name="blacklist_hostnames">
-				<categoryname>security.blacklist.custom</categoryname>
-				<optiontype>textarea</optiontype>
-			</option>
 			<!-- /security.blacklist.custom -->
 			<!-- security.antispam.captcha -->
 			<option name="captcha_type">
@@ -1704,5 +1700,6 @@ DESC:wcf.global.sortOrder.descending</selectoptions>
 		<option name="session_validate_ip_address" />
 		<option name="session_validate_user_agent" />
 		<option name="session_enable_virtualization" />
+		<option name="blacklist_hostnames" />
 	</delete>
 </data>
diff --git a/constants.php b/constants.php
index e38294011f..c32d15669c 100644
--- a/constants.php
+++ b/constants.php
@@ -80,7 +80,6 @@ define('USER_AUTHENTICATION_FAILURE_EXPIRATION', 30);
 define('SIGNATURE_SECRET', '');
 define('BLACKLIST_IP_ADDRESSES', '');
 define('BLACKLIST_USER_AGENTS', '');
-define('BLACKLIST_HOSTNAMES', '');
 define('CAPTCHA_TYPE', 'com.woltlab.wcf.recaptcha');
 define('REGISTER_USE_CAPTCHA', 1);
 define('LOST_PASSWORD_USE_CAPTCHA', 1);
diff --git a/wcfsetup/install/files/lib/system/WCF.class.php b/wcfsetup/install/files/lib/system/WCF.class.php
index 7c9ae4d70c..f3e2dac4f7 100644
--- a/wcfsetup/install/files/lib/system/WCF.class.php
+++ b/wcfsetup/install/files/lib/system/WCF.class.php
@@ -419,6 +419,10 @@ class WCF
         // https://github.com/WoltLab/WCF/issues/3674
         \define('REGISTER_ADMIN_NOTIFICATION', 0);
 
+        // The hostname blocklist was removed in 5.4.
+        // https://github.com/WoltLab/WCF/issues/3909
+        \define('BLACKLIST_HOSTNAMES', '');
+
         $filename = WCF_DIR . 'options.inc.php';
 
         // create options file if doesn't exist
@@ -551,18 +555,7 @@ class WCF
                 }
             }
         }
-        if (\defined('BLACKLIST_HOSTNAMES') && BLACKLIST_HOSTNAMES != '') {
-            if (!StringUtil::executeWordFilter(@\gethostbyaddr(UserUtil::getIpAddress()), BLACKLIST_HOSTNAMES)) {
-                if ($isAjax) {
-                    throw new AJAXException(
-                        self::getLanguage()->getDynamicVariable('wcf.ajax.error.permissionDenied'),
-                        AJAXException::INSUFFICIENT_PERMISSIONS
-                    );
-                } else {
-                    throw new PermissionDeniedException();
-                }
-            }
-        }
+
 
         // handle banned users
         if (self::getUser()->userID && self::getUser()->banned && !self::getUser()->hasOwnerAccess()) {
diff --git a/wcfsetup/install/files/options.inc.php b/wcfsetup/install/files/options.inc.php
index e319e37ef8..e5a7210d9b 100644
--- a/wcfsetup/install/files/options.inc.php
+++ b/wcfsetup/install/files/options.inc.php
@@ -26,7 +26,6 @@ if (\file_exists(WCF_DIR . 'cookiePrefix.txt')) {
 
 \define('BLACKLIST_IP_ADDRESSES', '');
 \define('BLACKLIST_USER_AGENTS', '');
-\define('BLACKLIST_HOSTNAMES', '');
 
 \define('CACHE_SOURCE_TYPE', 'disk');
 \define('IMAGE_ADAPTER_TYPE', 'gd');
diff --git a/wcfsetup/install/lang/de.xml b/wcfsetup/install/lang/de.xml
index 4242097b9b..e27051d9d3 100644
--- a/wcfsetup/install/lang/de.xml
+++ b/wcfsetup/install/lang/de.xml
@@ -1253,8 +1253,6 @@ ACHTUNG: Die oben genannten Meldungen sind stark gekürzt. Sie können Details z
 		<item name="wcf.acp.notice.showOrder.description"><![CDATA[Legt die Reihenfolge fest, in der die Hinweise angezeigt werden.]]></item>
 	</category>
 	<category name="wcf.acp.option">
-		<item name="wcf.acp.option.blacklist_hostnames"><![CDATA[Hostname ausschließen]]></item>
-		<item name="wcf.acp.option.blacklist_hostnames.description"><![CDATA[Ein Hostname pro Zeile]]></item>
 		<item name="wcf.acp.option.blacklist_ip_addresses"><![CDATA[IP-Adresse ausschließen]]></item>
 		<item name="wcf.acp.option.blacklist_ip_addresses.description"><![CDATA[Eine Adresse pro Zeile]]></item>
 		<item name="wcf.acp.option.blacklist_user_agents"><![CDATA[Browser-Kennung ausschließen]]></item>
diff --git a/wcfsetup/install/lang/en.xml b/wcfsetup/install/lang/en.xml
index 2a4e153609..41930a892f 100644
--- a/wcfsetup/install/lang/en.xml
+++ b/wcfsetup/install/lang/en.xml
@@ -1230,8 +1230,6 @@ ATTENTION: The messages listed above are greatly shortened. You can view details
 		<item name="wcf.acp.notice.showOrder.description"><![CDATA[Choose display order of notices.]]></item>
 	</category>
 	<category name="wcf.acp.option">
-		<item name="wcf.acp.option.blacklist_hostnames"><![CDATA[Block by Hostname]]></item>
-		<item name="wcf.acp.option.blacklist_hostnames.description"><![CDATA[You can specify which hostnames will be blacklisted. Enter one hostname per line.]]></item>
 		<item name="wcf.acp.option.blacklist_ip_addresses"><![CDATA[Block by IP Address]]></item>
 		<item name="wcf.acp.option.blacklist_ip_addresses.description"><![CDATA[You can specify which IP addresses will be blacklisted. Enter one IP address per line.]]></item>
 		<item name="wcf.acp.option.blacklist_user_agents"><![CDATA[Block by User-Agent]]></item>
-- 
2.20.1