HTTP_FILTER_CONTEXT Structure

The HTTP_FILTER_CONTEXT structure has the following form:

typedef struct _HTTP_FILTER_CONTEXT
{

DWORD    cbSize;                                  //IN
DWORD    Revision;                                //IN
PVOID    ServerContext;                           //IN
DWORD    ulReserved;                              //IN
BOOL     fIsSecurePort;                           //IN
PVOID    pFilterContext;                      //IN/OUT

BOOL    (WINAPI * GetServerVariable) (   
    struct _HTTP_FILTER_CONTEXT *    pfc,
    LPSTR      lpszVariableName,
    LPVOID     lpvBuffer,
    LPDWORD    lpdwSize
    );   

BOOL    (WINAPI * AddResponseHeaders) (   
    struct _HTTP_FILTER_CONTEXT *    pfc,
    LPSTR    lpszHeaders,
    DWORD    dwReserved
    );    

BOOL    (WINAPI * WriteClient)  (   
    struct _HTTP_FILTER_CONTEXT *    pfc,
    LPVOID     Buffer,
    LPDWORD    lpdwBytes,
    DWORD      dwReserved
    );    

VOID *     (WINAPI * AllocMem) (   
    struct _HTTP_FILTER_CONTEXT *    pfc,
    DWORD      cbSize,
    DWORD      dwReserved
    );   

BOOL    (WINAPI * ServerSupportFunction) (   
    struct _HTTP_FILTER_CONTEXT *    pfc,
    enum SF_REQ_TYPE    sfReq,
    PVOID       pData,
    DWORD       ul1,
    DWORD       ul2
    );    

} HTTP_FILTER_CONTEXT, *PHTTP_FILTER_CONTEXT;

The references to IN or IN/OUT above indicate whether the member applies to messages to the filter (IN) or both to and from the filter (IN/OUT).

Members

cbSize

Size of this structure, in bytes.

Revision

 Revision level of this structure. Less than or equal to the version of the  HTTP_FILTER_REVISION.

ServerContext

Reserved for server use.

ulReserved

Reserved for server use.

fIsSecurePort

TRUE indicates that this event is occurring over a secure port.

pFilterContext

A pointer to be used by the filter for any context information that the filter wants to associate with this request. Any memory associated with this request can be safely freed during the SF_NOTIFY_END_OF_NET_SESSION notification.

GetServerVariable

Pointer to a function to retrieve information about the server and this connection.  See CHttpServerContext::GetServerVariable for details. GetServerVariable takes the following parameters:

• pfc   Pointer to a filter context passed to CHttpFilter::HttpFilterProc.

• lpszVariableName   Server variable to retrieve.

• lpvBuffer   Buffer to store value of variable.

• lpdwSize   Size of buffer lpvBuffer.

AddResponseHeaders

Pointer to a function that adds a header to the HTTP response. See the description of HSE_REQ_SEND_RESPONSE_HEADER at CHttpServerContext::ServerSupportFunction for details. AddResponseHeaders takes the following parameters:

• pfc   Pointer to a filter context passed to CHttpFilter::HttpFilterProc.

• lpszHeaders   Pointer string containing headers to add.

• dwReserved   Reserved for future use. Must be 0.

WriteClient

Pointer to a function that sends raw data back to the client. See CHttpFilterContext::WriteClient for details. WriteClient takes the following parameters:

• pfc   Pointer passed to CHttpFilter::HttpFilterProc.

• Buffer   Buffer containing data to send to the client.

• lpdwBytes   Size of the buffer pointed to by Buffer.

• dwReserved   Reserved for future use.

AllocMem

Pointer to a function used to allocate memory. Any memory allocated with this function will automatically be freed when the request is completed. AllocMem takes the following parameters:

• pfc   Pointer passed to CHttpFilter::HttpFilterProc.

• cbSize   Size of the buffer to allocate.

• dwReserved   Reserved for future use.

ServerSupportFunction

Pointer to a function used to extend the ISAPI filter APIs. Parameters, listed below, are specific to the ISA used.

• pfc   Pointer to a function used to extend the ISAPI filter APIs.

• sfReq   Server function notification. Possible values:

  SF_REQ_SEND_RESPONSE_HEADER   Sends a complete HTTP server response header including the status, server version, message time and MIME version.  Server extensions should append other information at the end, such as Content-type, Content-length, and so forth, followed by an extra '\r\n'.

  SF_REQ_ADD_HEADERS_ON_DENIAL   If the server denies the HTTP request, add the specified headers to the server error response. This allows an authentication filter to advertise its services without filtering every request. Generally the headers will be WWW-Authenticate headers with custom authentication schemes, but no restriction is placed on what headers may be specified.

  SF_REQ_SET_NEXT_READ_SIZE   Only used by raw data filters that return SF_STATUS_READ_NEXT.

• pData   Pointer to a string. Specific to the ISA. See the table under the Comments section for the appropriate values for each sfReq value.

• ul1, ul2   Specific to the ISA. See the table under the Comments section for the appropriate values for each sfReq value.

Comments

Below are the corresponding possible values for the ServerSupportFunction parameters:

See AlsoCHttpFilter::HttpFilterProc, CHttpFilter::OnLog, CHttpServerContext, CHttpServerContext::GetServerVariable, CHttpServerContext::ServerSupportFunction, CHttpServerContext::WriteClient