From 06c3a8a9dbb3b582b4be26b67fe534734f74b38b Mon Sep 17 00:00:00 2001
From: Alexander Ebert <ebert@woltlab.com>
Date: Tue, 9 Jul 2013 15:22:59 +0200
Subject: [PATCH] Prevent possible issues with gzip compression headers

Fixes #1405
---
 .../files/lib/util/HeaderUtil.class.php       | 52 +++++++++++--------
 1 file changed, 31 insertions(+), 21 deletions(-)

diff --git a/wcfsetup/install/files/lib/util/HeaderUtil.class.php b/wcfsetup/install/files/lib/util/HeaderUtil.class.php
index 94eecb09dc..1694969680 100644
--- a/wcfsetup/install/files/lib/util/HeaderUtil.class.php
+++ b/wcfsetup/install/files/lib/util/HeaderUtil.class.php
@@ -16,6 +16,12 @@ use wcf\system\WCF;
  * @category	Community Framework
  */
 final class HeaderUtil {
+	/**
+	 * gzip compression
+	 * @var	boolean
+	 */
+	protected static $enableGzipCompression = false;
+	
 	/**
 	 * output HTML
 	 * @var	string
@@ -44,10 +50,23 @@ final class HeaderUtil {
 			self::sendNoCacheHeaders();
 		}
 		
-		ob_start(array('wcf\util\HeaderUtil', 'parseOutput'));
+		if (HTTP_ENABLE_GZIP && HTTP_GZIP_LEVEL > 0 && HTTP_GZIP_LEVEL < 10 && !defined('HTTP_DISABLE_GZIP')) {
+			if (function_exists('gzcompress') && !@ini_get('zlib.output_compression') && !@ini_get('output_handler') && isset($_SERVER['HTTP_ACCEPT_ENCODING']) && strstr($_SERVER['HTTP_ACCEPT_ENCODING'], 'gzip')) {
+				self::$enableGzipCompression = true;
+				
+				if (strstr($_SERVER['HTTP_ACCEPT_ENCODING'], 'x-gzip')) {
+					@header('Content-Encoding: x-gzip');
+				}
+				else {
+					@header('Content-Encoding: gzip');
+				}
+			}
+		}
 		
 		// send Internet Explorer compatibility mode
 		@header('X-UA-Compatible: IE=edge');
+		
+		ob_start(array('wcf\util\HeaderUtil', 'parseOutput'));
 	}
 	
 	/**
@@ -84,26 +103,17 @@ final class HeaderUtil {
 		// class. Use HeaderUtil::$output to modify it.
 		if (!defined('NO_IMPORTS')) EventHandler::getInstance()->fireAction('wcf\util\HeaderUtil', 'parseOutput');
 		
-		// enable gzip compression
-		if (HTTP_ENABLE_GZIP && HTTP_GZIP_LEVEL > 0 && HTTP_GZIP_LEVEL < 10 && !defined('HTTP_DISABLE_GZIP')) {
-			if (function_exists('gzcompress') && !@ini_get('zlib.output_compression') && !@ini_get('output_handler') && isset($_SERVER['HTTP_ACCEPT_ENCODING']) && strstr($_SERVER['HTTP_ACCEPT_ENCODING'], 'gzip')) {
-				if (strstr($_SERVER['HTTP_ACCEPT_ENCODING'], 'x-gzip')) {
-					@header('Content-Encoding: x-gzip');
-				}
-				else {
-					@header('Content-Encoding: gzip');
-				}
-				
-				$size = strlen(self::$output);
-				$crc = crc32(self::$output);
-				
-				$newOutput = "\x1f\x8b\x08\x00\x00\x00\x00\x00\x00\xff";
-				$newOutput .= substr(gzcompress(self::$output, HTTP_GZIP_LEVEL), 2, -4);
-				$newOutput .= pack('V', $crc);
-				$newOutput .= pack('V', $size);
-				
-				self::$output = $newOutput;
-			}
+		// gzip compression
+		if (self::$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, HTTP_GZIP_LEVEL), 2, -4);
+			$newOutput .= pack('V', $crc);
+			$newOutput .= pack('V', $size);
+			
+			self::$output = $newOutput;
 		}
 		
 		return self::$output;
-- 
2.20.1