FwpmTransactionBegin0 function (fwpmu.h)

The FwpmTransactionBegin0 function begins an explicit transaction within the current session.

Syntax

DWORD FwpmTransactionBegin0(
 [in] HANDLE engineHandle,
 [in] UINT32 flags
);

Parameters

[in] engineHandle

Type: HANDLE

Handle for an open session to the filter engine. Call FwpmEngineOpen0 to open a session to the filter engine.

[in] flags

Type: UINT32

Possible values:

Return value

Type: DWORD

Remarks

This function cannot be called from within a transaction. It will fail with FWP_E_TXN_IN_PROGRESS. See Object Management for more information about transactions.

For a read-only transaction, the caller needs FWPM_ACTRL_BEGIN_READ_TXN access to the filter engine. For a read/write transaction, the caller needs FWPM_ACTRL_BEGIN_WRITE_TXN access to the filter engine. See Access Control for more information.

FwpmTransactionBegin0 is a specific implementation of FwpmTransactionBegin. See WFP Version-Independent Names and Targeting Specific Versions of Windows for more information.

Examples

The following C++ example illustrates wrapping the FwpmFilterAdd0 function in an FWP transaction.

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

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

void main()
{
 HANDLE engineHandle = NULL; 

 FWPM_FILTER0 fwpFilter;

 RtlZeroMemory(&fwpFilter, sizeof(FWPM_FILTER0));
 fwpFilter.layerKey = FWPM_LAYER_ALE_AUTH_RECV_ACCEPT_V4;
 fwpFilter.action.type = FWP_ACTION_BLOCK;
 fwpFilter.weight.type = FWP_EMPTY;
 fwpFilter.numFilterConditions = 0;

 DWORD result = ERROR_SUCCESS; 
 DWORD fwpTxStatus = ERROR_SUCCESS;

 printf("Opening filter engine.\n");
 result = FwpmEngineOpen0(NULL, RPC_C_AUTHN_WINNT, NULL, NULL, &engineHandle);
 if (result != ERROR_SUCCESS)
 { 
 printf("FwpmEngineOpen0 failed (%d).\n", result);
 return;
 }
 
 printf("Adding filter to permit traffic for Application 1.\n");
 fwpTxStatus = FwpmTransactionBegin0(engineHandle, NULL);
 if (fwpTxStatus != ERROR_SUCCESS)
 { 
 printf("FwpmTransactionBegin0 failed (%d).\n", fwpTxStatus);
 return;
 }

 result = FwpmFilterAdd0(engineHandle, &fwpFilter, NULL, NULL);
 if (result != ERROR_SUCCESS)
 { 
 printf("FwpmFilterAdd0 failed (%d).\n", result);
 return;
 }

 result = FwpmTransactionCommit0(engineHandle);
 if (result != ERROR_SUCCESS)
 { 
 printf("FwpmTransactionCommit0 failed (%d).\n", result);
 return;
 }
 else
 {
 printf("Filter transaction (adding a filter) committed successfully.\n");
 }

 return;
}
// ----------------------------------------------------------------------

Requirements

See also

FwpmTransactionAbort0

FwpmTransactionCommit0