FWPM_FILTER_CONDITION0 structure (fwpmtypes.h)

Article
02/22/2024

The FWPM_FILTER_CONDITION0 structure expresses a filter condition that must be true for the action to be taken.

Syntax

typedef struct FWPM_FILTER_CONDITION0_ {
  GUID                 fieldKey;
  FWP_MATCH_TYPE       matchType;
  FWP_CONDITION_VALUE0 conditionValue;
} FWPM_FILTER_CONDITION0;

Members

fieldKey

GUID of the field to be tested. The available keys are listed under Filtering Condition Identifiers.

matchType

A FWP_MATCH_TYPE value that specifies the type of match to be performed.

conditionValue

A FWP_CONDITION_VALUE0 structure that contains the value to match the field against.

Remarks

Field GUIDs are only unique within a layer, so both the field GUID and the layer GUID are required to uniquely identify a field.

The data type of

FWP_MATCH_TYPE for detailed compatibility rules.

FWPM_FILTER_CONDITION0 is a specific implementation of FWPM_FILTER_CONDITION. See WFP Version-Independent Names and Targeting Specific Versions of Windows for more information.

Examples

The following C++ example shows how to initialize and add conditions to a filter.

#include <windows.h>
#include <fwpmu.h>
#include <stdio.h>

#pragma comment(lib, "Fwpuclnt.lib")

// Some application to use for filter testing.
#define FILE0_PATH L"C:\\Program Files\\AppDirectory\\SomeApplication.exe"

void main()
{
    FWP_BYTE_BLOB *fwpApplicationByteBlob;
    FWPM_FILTER0 fwpFilter;
    FWPM_FILTER_CONDITION0 fwpConditions[4];
    int conCount = 0;
    DWORD result = ERROR_SUCCESS; 

    fwpApplicationByteBlob = (FWP_BYTE_BLOB*) malloc(sizeof(FWP_BYTE_BLOB));
    
    printf("Retrieving application identifier for filter testing.\n"); 
    result = FwpmGetAppIdFromFileName0(FILE0_PATH, &fwpApplicationByteBlob);
    if (result != ERROR_SUCCESS)
    {
        printf("FwpmGetAppIdFromFileName failed (%d).\n", result);
        return;
    }

      // Application identifier filter condition.
      fwpConditions[conCount].fieldKey = FWPM_CONDITION_ALE_APP_ID;
      fwpConditions[conCount].matchType = FWP_MATCH_EQUAL;
      fwpConditions[conCount].conditionValue.type = FWP_BYTE_BLOB_TYPE;
      fwpConditions[conCount].conditionValue.byteBlob = fwpApplicationByteBlob;
            
      ++conCount;

      // TCP protocol filter condition
      fwpConditions[conCount].fieldKey = FWPM_CONDITION_IP_PROTOCOL;
      fwpConditions[conCount].matchType = FWP_MATCH_EQUAL;
      fwpConditions[conCount].conditionValue.type = FWP_UINT8;
      fwpConditions[conCount].conditionValue.uint8 = IPPROTO_TCP;

      ++conCount;

      // Add conditions and condition count to a filter.
      memset(&fwpFilter, 0, sizeof(FWPM_FILTER0));

      fwpFilter.numFilterConditions = conCount;
      if (conCount > 0)
        fwpFilter.filterCondition = fwpConditions;

      // Finish initializing filter...

    return;
}

Requirements

Requirement	Value
Minimum supported client	Windows Vista [desktop apps only]
Minimum supported server	Windows Server 2008 [desktop apps only]
Header	fwpmtypes.h