Web Filter Structures

The Forefront TMG Web proxy works with the structures described here.

HTTP_FILTER_CONTEXT

The HTTP_FILTER_CONTEXT structure is used for passing control and information associated with the current, active HTTP session in event notifications that are sent by the Forefront TMG Web proxy to Web filters by calling HttpFilterProc and HttpWPXFilterProc. This structure includes pointers to the following functions:

• GetServerVariable
• AddResponseHeaders
• WriteClient
• AllocMem
• ServerSupportFunction

HTTP_FILTER_VERSION

The HTTP_FILTER_VERSION structure is used by the GetFilterVersion and the GetWPXFilterVersion functions to set the filter version information and to specify the types of event notifications which are to be sent to a Web filter.

WPX_FILTER_CONTEXT

The WPX_FILTER_CONTEXT structure is used for passing information associated with the current, active HTTP session. This structure extends the HTTP_FILTER_CONTEXT structure and adds the following functions:

• WriteServer
• AllocMemoryPerRequest
• GetAuthSchemeStatus
• WPXSupportFunction

Note  To use these functions you must get a pointer to the WPX_FILTER_CONTEXT structure from a pointer to an HTTP_FILTER_CONTEXT structure. To do so, use the TO_WPX_FILTER_CONTEXT macro as follows:

  WPX_FILTER_CONTEXT* pwfc = TO_WPX_FILTER_CONTEXT(pfc);
  if (pwfc != NULL) {
  ...
  }

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Build date: 11/30/2009