From 91b46ad444a1c0d90ae0c309b1386fbd5919f30b Mon Sep 17 00:00:00 2001
From: =?utf8?q?Tim=20D=C3=BCsterhus?= <duesterhus@woltlab.com>
Date: Fri, 23 Oct 2020 16:17:19 +0200
Subject: [PATCH] Remove in-application gzip compression

Resolves #3634
---
 com.woltlab.wcf/option.xml                    |  6 +--
 constants.php                                 |  1 -
 .../install/files/lib/system/WCF.class.php    | 32 ++------------
 .../files/lib/system/WCFSetup.class.php       |  2 -
 .../files/lib/util/HeaderUtil.class.php       | 43 ++-----------------
 wcfsetup/install/files/options.inc.php        |  2 -
 wcfsetup/install/lang/de.xml                  |  2 -
 wcfsetup/install/lang/en.xml                  |  2 -
 8 files changed, 8 insertions(+), 82 deletions(-)

diff --git a/com.woltlab.wcf/option.xml b/com.woltlab.wcf/option.xml
index 6ef303a26f..9eafcf56db 100644
--- a/com.woltlab.wcf/option.xml
+++ b/com.woltlab.wcf/option.xml
@@ -604,11 +604,6 @@ private:wcf.acp.option.exception_privacy.private</selectoptions>
 				<optiontype>boolean</optiontype>
 				<defaultvalue>1</defaultvalue>
 			</option>
-			<option name="http_enable_gzip">
-				<categoryname>general.system.http</categoryname>
-				<optiontype>boolean</optiontype>
-				<defaultvalue>1</defaultvalue>
-			</option>
 			<!-- /general.system.http -->
 			<!-- general.system.packageServer -->
 			<option name="package_server_auth_code">
@@ -1711,5 +1706,6 @@ DESC:wcf.global.sortOrder.descending</selectoptions>
 		</options>
 	</import>
 	<delete>
+		<option name="http_enable_gzip" />
 	</delete>
 </data>
diff --git a/constants.php b/constants.php
index 58157cb8c4..2ca1adb153 100644
--- a/constants.php
+++ b/constants.php
@@ -68,7 +68,6 @@ define('SEARCH_ENGINE', 'mysql');
 define('EXCEPTION_PRIVACY', 'public');
 define('COOKIE_PREFIX', 'wcf21_');
 define('HTTP_SEND_X_FRAME_OPTIONS', 1);
-define('HTTP_ENABLE_GZIP', 1);
 define('PACKAGE_SERVER_AUTH_CODE', '');
 define('PROXY_SERVER_HTTP', '');
 define('IP_ADDRESS_SEARCH_ENGINE', '');
diff --git a/wcfsetup/install/files/lib/system/WCF.class.php b/wcfsetup/install/files/lib/system/WCF.class.php
index dfddbcda02..93ae9dea43 100644
--- a/wcfsetup/install/files/lib/system/WCF.class.php
+++ b/wcfsetup/install/files/lib/system/WCF.class.php
@@ -283,34 +283,6 @@ class WCF {
 			// 
 			// ob_get_level() can return values > 1, if the PHP setting `output_buffering` is on
 			while (ob_get_level()) ob_end_clean();
-			
-			// Some webservers are broken and will apply gzip encoding at all cost, but they fail
-			// to set a proper `Content-Encoding` HTTP header and mess things up even more.
-			// Especially the `identity` value appears to be unrecognized by some of them, hence
-			// we'll just gzip the output of the exception to prevent them from tampering.
-			// This part is copied from `HeaderUtil` in order to isolate the exception handler!
-			if (defined('HTTP_ENABLE_GZIP') && HTTP_ENABLE_GZIP && !defined('HTTP_DISABLE_GZIP')) {
-				if (function_exists('gzcompress') && !@ini_get('zlib.output_compression') && !@ini_get('output_handler') && isset($_SERVER['HTTP_ACCEPT_ENCODING']) && strpos($_SERVER['HTTP_ACCEPT_ENCODING'], 'gzip') !== false) {
-					if (strpos($_SERVER['HTTP_ACCEPT_ENCODING'], 'x-gzip') !== false) {
-						@header('Content-Encoding: x-gzip');
-					}
-					else {
-						@header('Content-Encoding: gzip');
-					}
-					
-					ob_start(function($output) {
-						$size = strlen($output);
-						$crc = crc32($output);
-						
-						$newOutput = "\x1f\x8b\x08\x00\x00\x00\x00\x00\x00\xff";
-						$newOutput .= substr(gzcompress($output, 1), 2, -4);
-						$newOutput .= pack('V', $crc);
-						$newOutput .= pack('V', $size);
-						
-						return $newOutput;
-					});
-				}
-			}
 		}
 		
 		@header('HTTP/1.1 503 Service Unavailable');
@@ -401,6 +373,10 @@ class WCF {
 		// The session timeout is fully managed since 5.4.
 		define('SESSION_TIMEOUT', 3600);
 		
+		// gzip compression is removed in 5.4.
+		// https://github.com/WoltLab/WCF/issues/3634
+		define('HTTP_ENABLE_GZIP', 0);
+		
 		$filename = WCF_DIR.'options.inc.php';
 		
 		// create options file if doesn't exist
diff --git a/wcfsetup/install/files/lib/system/WCFSetup.class.php b/wcfsetup/install/files/lib/system/WCFSetup.class.php
index 08c78c762c..d8868b779e 100644
--- a/wcfsetup/install/files/lib/system/WCFSetup.class.php
+++ b/wcfsetup/install/files/lib/system/WCFSetup.class.php
@@ -34,8 +34,6 @@ use wcf\util\XML;
 
 // define
 define('PACKAGE_ID', 0);
-define('HTTP_ENABLE_GZIP', 0);
-define('HTTP_GZIP_LEVEL', 0);
 define('HTTP_SEND_X_FRAME_OPTIONS', 0);
 define('CACHE_SOURCE_TYPE', 'disk');
 define('MODULE_MASTER_PASSWORD', 1);
diff --git a/wcfsetup/install/files/lib/util/HeaderUtil.class.php b/wcfsetup/install/files/lib/util/HeaderUtil.class.php
index 4c96297ed1..0ca4c32d03 100644
--- a/wcfsetup/install/files/lib/util/HeaderUtil.class.php
+++ b/wcfsetup/install/files/lib/util/HeaderUtil.class.php
@@ -2,7 +2,6 @@
 namespace wcf\util;
 use wcf\system\application\ApplicationHandler;
 use wcf\system\event\EventHandler;
-use wcf\system\exception\SystemException;
 use wcf\system\request\RequestHandler;
 use wcf\system\request\RouteHandler;
 use wcf\system\session\SessionHandler;
@@ -18,17 +17,10 @@ use wcf\system\WCF;
  */
 final class HeaderUtil {
 	/**
-	 * gzip level to user
-	 * @var	integer
+	 * @deprecated 5.4 - gzip support was removed.
 	 */
 	const GZIP_LEVEL = 1;
 	
-	/**
-	 * gzip compression
-	 * @var	boolean
-	 */
-	protected static $enableGzipCompression = false;
-	
 	/**
 	 * output HTML
 	 * @var	string
@@ -79,19 +71,6 @@ final class HeaderUtil {
 			self::sendNoCacheHeaders();
 		}
 		
-		if (HTTP_ENABLE_GZIP && !defined('HTTP_DISABLE_GZIP')) {
-			if (function_exists('gzcompress') && !@ini_get('zlib.output_compression') && !@ini_get('output_handler') && isset($_SERVER['HTTP_ACCEPT_ENCODING']) && strpos($_SERVER['HTTP_ACCEPT_ENCODING'], 'gzip') !== false) {
-				self::$enableGzipCompression = true;
-				
-				if (strpos($_SERVER['HTTP_ACCEPT_ENCODING'], 'x-gzip') !== false) {
-					@header('Content-Encoding: x-gzip');
-				}
-				else {
-					@header('Content-Encoding: gzip');
-				}
-			}
-		}
-		
 		// send X-Frame-Options
 		if (HTTP_SEND_X_FRAME_OPTIONS) {
 			@header('X-Frame-Options: SAMEORIGIN');
@@ -109,12 +88,9 @@ final class HeaderUtil {
 	}
 	
 	/**
-	 * Disables gzip compression on runtime in case of an exception. You should not call
-	 * this method at all, it exists for exception handling only.
+	 * @deprecated 5.4 - This method is a no-op, as gzip support was removed.
 	 */
-	public static function exceptionDisableGzip() {
-		self::$enableGzipCompression = false;
-	}
+	public static function exceptionDisableGzip() { }
 	
 	/**
 	 * Parses the rendered output.
@@ -149,19 +125,6 @@ final class HeaderUtil {
 		// class. Use HeaderUtil::$output to modify it.
 		if (!defined('NO_IMPORTS')) EventHandler::getInstance()->fireAction(self::class, 'parseOutput');
 		
-		// gzip compression
-		if (self::$enableGzipCompression) {
-			$size = strlen(self::$output);
-			$crc = crc32(self::$output);
-			
-			$newOutput = "\x1f\x8b\x08\x00\x00\x00\x00\x00\x00\xff";
-			$newOutput .= substr(gzcompress(self::$output, self::GZIP_LEVEL), 2, -4);
-			$newOutput .= pack('V', $crc);
-			$newOutput .= pack('V', $size);
-			
-			self::$output = $newOutput;
-		}
-		
 		return self::$output;
 	}
 	
diff --git a/wcfsetup/install/files/options.inc.php b/wcfsetup/install/files/options.inc.php
index 0f3807648b..4d07ccb8d1 100644
--- a/wcfsetup/install/files/options.inc.php
+++ b/wcfsetup/install/files/options.inc.php
@@ -20,8 +20,6 @@ define('COOKIE_PREFIX', $prefix);
 define('COOKIE_PATH', '');
 define('COOKIE_DOMAIN', '');
 
-define('HTTP_ENABLE_GZIP', 0);
-define('HTTP_GZIP_LEVEL', 1);
 define('HTTP_SEND_X_FRAME_OPTIONS', 0);
 
 define('BLACKLIST_IP_ADDRESSES', '');
diff --git a/wcfsetup/install/lang/de.xml b/wcfsetup/install/lang/de.xml
index eeb6e361a0..6552a97087 100644
--- a/wcfsetup/install/lang/de.xml
+++ b/wcfsetup/install/lang/de.xml
@@ -1320,8 +1320,6 @@ ACHTUNG: Die oben genannten Meldungen sind stark gekürzt. Sie können Details z
 		<item name="wcf.acp.option.error.controllerReplacementUnknown"><![CDATA[Der Controller „{$urlControllerReplacementError}“ ist unbekannt.]]></item>
 		<item name="wcf.acp.option.error.tooHigh"><![CDATA[Der angegebene Wert ist zu hoch.{if $option->maxvalue !== null} Der maximale Wert ist {#$option->maxvalue}.{/if}]]></item>
 		<item name="wcf.acp.option.error.tooLow"><![CDATA[Der angegebene Wert ist zu gering.{if $option->minvalue !== null} Der minimale Wert ist {#$option->minvalue}.{/if}]]></item>
-		<item name="wcf.acp.option.http_enable_gzip"><![CDATA[Gzip-Komprimierung aktivieren]]></item>
-		<item name="wcf.acp.option.http_enable_gzip.description"><![CDATA[Aktiviert die Komprimierung der Inhalte bei der Übertragung vom Server an den Client. Dies reduziert den Traffic und kann den Ladevorgang erheblich beschleunigen.]]></item>
 		<item name="wcf.acp.option.http_send_x_frame_options"><![CDATA[Einbindung in einem Frame verhindern]]></item>
 		<item name="wcf.acp.option.http_send_x_frame_options.description"><![CDATA[Sendet den <a href="https://de.wikipedia.org/wiki/Clickjacking" class="externalURL">„X-Frame-Options“</a> Header, um die Einbettung dieser Seite in einem Frame zu verhindern (sendet „SAMEORIGIN“).]]></item>
 		<item name="wcf.acp.option.image_adapter_type"><![CDATA[Grafik-Bibliothek]]></item>
diff --git a/wcfsetup/install/lang/en.xml b/wcfsetup/install/lang/en.xml
index 23abb23ecd..e682e140af 100644
--- a/wcfsetup/install/lang/en.xml
+++ b/wcfsetup/install/lang/en.xml
@@ -1297,8 +1297,6 @@ ATTENTION: The messages listed above are greatly shortened. You can view details
 		<item name="wcf.acp.option.error.controllerReplacementUnknown"><![CDATA[The controller “{$urlControllerReplacementError}” is unknown.]]></item>
 		<item name="wcf.acp.option.error.tooHigh"><![CDATA[Exceeds the maximum value{if $option->maxvalue !== null} of {#$option->maxvalue}{/if}.]]></item>
 		<item name="wcf.acp.option.error.tooLow"><![CDATA[Under the minimum value{if $option->minvalue !== null} of {#$option->minvalue}{/if}.]]></item>
-		<item name="wcf.acp.option.http_enable_gzip"><![CDATA[Enable gzip-compression]]></item>
-		<item name="wcf.acp.option.http_enable_gzip.description"><![CDATA[Compresses content transferred to users, it also reduces traffic and page load times. It does not affect files, e.g. images.]]></item>
 		<item name="wcf.acp.option.http_send_x_frame_options"><![CDATA[Disallow embedding in a frame]]></item>
 		<item name="wcf.acp.option.http_send_x_frame_options.description"><![CDATA[Sends the <a href="https://en.wikipedia.org/wiki/Clickjacking" class="externalURL">“X-Frame-Options”</a> header to prevent 3rd party sites from embedding this site in a frame (sends “SAMEORIGIN”).]]></item>
 		<item name="wcf.acp.option.image_adapter_type"><![CDATA[Graphics Library]]></item>
-- 
2.20.1