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FwpmTransactionBegin0 function (fwpmu.h)

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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:

Transaction flag Meaning
0
 Begin read/write transaction.
FWPM_TXN_READ_ONLY
 Begin read-only transaction.

Return value

Type: DWORD

Return code/value Description
ERROR_SUCCESS
0
 The transaction was started successfully.
FWP_E_* error code
0x80320001—0x80320039
 A Windows Filtering Platform (WFP) specific error. See WFP Error Codes for details.
RPC_* error code
0x80010001—0x80010122
 Failure to communicate with the remote or local firewall engine.

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

Requirement Value
Minimum supported client Windows Vista [desktop apps only]
Minimum supported server Windows Server 2008 [desktop apps only]
Target Platform Windows
Header fwpmu.h
Library Fwpuclnt.lib
DLL Fwpuclnt.dll

See also

FwpmTransactionAbort0

FwpmTransactionCommit0