AddHeader Callback Function

Article
08/13/2010

The AddHeader callback function adds an HTTP header to an incoming request after an SF_NOTIFY_PREPROC_HEADERS or SF_NOTIFY_AUTH_COMPLETE event notification, to an incoming response after an SF_NOTIFY_RECEIVE_RESPONSE_HEADERS notification, or to an outgoing response after an SF_NOTIFY_SEND_RESPONSE notification. For more information about the types of event notifications that are sent to Web filters, see Event Notifications.

The AddHeader callback function is declared as:

Syntax

BOOL WINAPI * AddHeader(
  __in  struct _HTTP_FILTER_CONTEXT* pfc,
  __in  LPSTR lpszName,
  __in  LPSTR lpszValue
);

Parameters

pfc
Pointer to the HTTP_FILTER_CONTEXT data structure that is associated with the current, active HTTP session. Pass the filter context in this parameter.
lpszName
Pointer to a null-terminated string containing the name of the header to add. Header names should include the trailing colon (:). This parameter is not case-sensitive.
lpszValue
Pointer to a null-terminated string containing the new value to add to the header, or to "\0" to add a header with an empty value.

Return Value

This callback function returns TRUE if the call is successful; otherwise, it returns FALSE. To obtain extended error information, call GetLastError, which may return one of the following Windows system error codes:

ERROR_SUCCESS
The header was successfully added. This error code is returned when the callback function returns TRUE.
ERROR_INVALID_PARAMETER
The value specified in the lpszValue parameter is invalid. This error code is also returned after an SF_NOTIFY_AUTH_COMPLETE notification if the filter tries to modify the URL, method, or version portion of the request line.
ERROR_NOT_ENOUGH_MEMORY
Not enough memory was available to complete the requested operation.
ERROR_NOT_SUPPORTED
The request is an HTTP 0.9 request, or the value specified in the lpszName parameter is not valid.

Remarks

A pointer to this function is included as a member of the following structures:

Requirements

Server	Requires Windows Server 2008 R2 or Windows Server 2008 x64 Edition with SP2.
Version	Requires Forefront Threat Management Gateway (TMG) 2010.
Header	Declared in Wpxhttpfilt.h.
DLL	Requires W3Filter.dll.