FWPS_CALLOUT_CLASSIFY_FN2 callback function (fwpsk.h)

Article
10/21/2021

The filter engine calls a callout's classifyFn2 callout function whenever there is data to be processed by the callout.

Note classifyFn2 is the specific version of classifyFn used in Windows 8 and later. See WFP Version-Independent Names and Targeting Specific Versions of Windows for more information. For Windows 7, classifyFn1 is available. For Windows Vista, classifyFn0 is available.

Syntax

FWPS_CALLOUT_CLASSIFY_FN2 FwpsCalloutClassifyFn2;

void FwpsCalloutClassifyFn2(
  [in]                const FWPS_INCOMING_VALUES0 *inFixedValues,
  [in]                const FWPS_INCOMING_METADATA_VALUES0 *inMetaValues,
  [in, out, optional] void *layerData,
  [in, optional]      const void *classifyContext,
  [in]                const FWPS_FILTER2 *filter,
  [in]                UINT64 flowContext,
  [in, out]           FWPS_CLASSIFY_OUT0 *classifyOut
)
{...}

Parameters

[in] inFixedValues

A pointer to an FWPS_INCOMING_VALUES0 structure. This structure contains the values for each of the data fields in the layer being filtered.

[in] inMetaValues

A pointer to an FWPS_INCOMING_METADATA_VALUES0 structure. This structure contains the values for each of the metadata fields in the layer being filtered.

[in, out, optional] layerData

A pointer to a structure that describes the raw data in the layer being filtered. This parameter might be NULL, depending on the layer being filtered and the conditions under which the classifyFn2 callout function is called. For the stream layer, this parameter points to an FWPS_STREAM_CALLOUT_IO_PACKET0 structure. For all of the other layers, this parameter points to a NET_BUFFER_LIST structure if it is not NULL.

[in, optional] classifyContext

A pointer to context data associated with the callout driver by the filter engine.

[in] filter

A pointer to an FWPS_FILTER2 structure. This structure describes the filter that specifies the callout for the filter's action.

[in] flowContext

A UINT64-typed variable that contains the context associated with the data flow. If no context is associated with the data flow, then this parameter is zero. If the callout is added to the filter engine at a filtering layer that does not support data flows, the classifyFn2 callout function should ignore this parameter.

[in, out] classifyOut

A pointer to an FWPS_CLASSIFY_OUT0 structure that receives any data that the classifyFn2 callout function returns to the caller.

Return value

None

Remarks

A callout driver registers a callout's callout functions with the filter engine by calling the FwpsCalloutRegister2 function.

The filter engine calls a callout's classifyFn2 callout function with data to be processed whenever all of the test conditions are true for a filter in the filter engine that specifies the callout for the filter's action.

A callout's classifyFn2 callout function should clear the FWPS_RIGHT_ACTION_WRITE flag in the rights member of the FWPS_CLASSIFY_OUT0 structure in any of the following situations:

When the classifyFn2 callout function sets the actionType member of the FWPS_CLASSIFY_OUT0 structure to FWP_ACTION_BLOCK.
When the classifyFn2 callout function sets the actionType member of the FWPS_CLASSIFY_OUT0 structure to FWP_ACTION_PERMIT and the FWPS_FILTER_FLAG_CLEAR_ACTION_RIGHT flag is set in the Flags member of the FWPS_FILTER2 structure.
When a callout has indicated that it intends to modify the clone net buffer list by setting the intendToModify parameter to TRUE in a call to the FwpsReferenceNetBufferList0 function.
This function is essentially identical to the previous version, classifyFn1. However, the updated FWPS_FILTER2 structure is pointed to by the filter parameter and the layerData parameter is optional.

Requirements

Requirement	Value
Minimum supported client	Available starting with Windows 8.
Target Platform	Windows
Header	fwpsk.h (include Fwpsk.h)
IRQL	<= DISPATCH_LEVEL