FIX: Incorrect response or connection fails in IIS 7.5 after an ISAPI filter registers for SF_NOTIFY_SEND_RAW_DATA event notifications

Consider the following scenario:

• You install Internet Information Services (IIS) 7.5 on a computer that is running Windows Server 2008 R2 or Windows 7.
• You add an ISAPI filter that registers for SF_NOTIFY_SEND_RAW_DATA event notifications in IIS.
• The computer that is running IIS 7.5 receives a Client HTTP request that contains a Range header.

In this scenario, one of the following symptoms occurs:

• If the response data size is equal to 8 MB or is less than 8 MB, IIS sends a response that states that the data length is equal to the Content-Range header, and an incorrect Content-Length header is returned in the response. Therefore, the client waits for data that does not exist.
  
  For example, the client sends the following request to the computer that is running IIS:
  
  GET /examplefile.txt HTTP/1.1
  
  Range: bytes=1000-2000
  
  Host: localhost
  The response to this request resembles the following:
  
  HTTP/1.1 206 Partial Content
  
  Content-Length: 8192000
  
  Content-Type: text/plain
  
  Last-Modified: <Day, Date and time>
  
  Accept-Ranges: bytes
  
  ETag: "0e7ef5bd70cb1:0"
  
  Server: Microsoft-IIS/7.5
  
  X-Powered-By: ASP.NET
  
  Date: Date and time
  
  Content-Range: bytes 1000-2000/8192000
  Note The correct value of the Content-Length header for the response is 1001. However, this response contains a value of 8192000.
• If the response data size is greater than 8 MB, the client connection fails. Additionally, the following error message is logged in the HTTP API error log:
  
  Connection_Dropped.

Note After you apply the following hotfix, the Range header is not processed if the response is larger than 8 MB. The 14.35.2 section of Request for Comments (RFC) 2616 states that a server may ignore the Range header.

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that described in this article. Apply this hotfix only to systems that are experiencing the problem described in this article. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft website:

http://support.microsoft.com/contactus/?ws=support

Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Prerequisites

To apply this hotfix, you must have IIS 7.5 installed on a computer that is running one of the following operating systems:

• Windows 7
• Windows 7 Service Pack 1 (SP1)
• Windows Server 2008 R2
• Windows Server 2008 R2 Service Pack 1 (SP1)

Restart requirement

After you install this hotfix, you must restart the computer if IIS was running when you installed this hotfix.

Hotfix replacement information

This hotfix does not replace a previously released hotfix.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.

For all supported x86-based versions of Windows 7

For all supported x64-based versions of Windows 7 and of Windows Server 2008 R2

For all supported IA-64–based versions of Windows Server 2008 R2