Prevent possible issues with gzip compression headers

Fixes #1405

diff --git a/wcfsetup/install/files/lib/util/HeaderUtil.class.php b/wcfsetup/install/files/lib/util/HeaderUtil.class.php
index 94eecb09dcb4a93a3a744af52422c37efc118288..1694969680b3c8b8b807965d143222f320f1634c 100644 (file)
--- 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;