You can use this support function to request that IIS send a complete HTTP response header to the client browser, including the HTTP status, server version, message time, and MIME version. Your filter can also, optionally, append other header information to the end of IIS-generated header, such as Content-Type or Content-Length.

BOOL WINAPI * ServerSupportFunction(
      enum SF_REQ_TYPE sfServerSupportFunction,
      PVOID pData,
      DWORD ul1,
      DWORD ul2


  • pfc
    Points to the HTTP_FILTER_CONTEXT Structure that is associated with the current, active HTTP transaction.

  • sfServerSupportFunction
    The name of the Server Support function, which in this case must be set to SF_REQ_SEND_RESPONSE_HEADER.

  • pData
    Points to a null-terminated string that contains an HTTP status string, such as "401 Access Denied." If pData is set to NULL, then the default response, "200 OK," will be sent in the response header.

  • ul1
    Points to a null-terminated string that contains the optional HTTP headers that you want to be appended to the response header.

  • ul2
    Unused in this support function.


If you append your own headers to the server-generated headers, you must terminate the header string with an extra carriage return and linefeed.

This support function must be called only once per HTTP request.


Client: Requires Windows XP Professional, Windows 2000 Professional, or Windows NT Workstation 4.0.

Server: Requires Windows Server 2003, Windows 2000 Server, or Windows NT Server 4.0.

Product: IIS

Header: Declared in httpfilt.h.