ISendResponseProvider::SetLogData Method

Article
06/14/2022

Configures logging information for the current response.

Syntax

virtual HRESULT SetLogData(  
   IN VOID* pLogData  
) = 0;

Parameters

pLogData
[IN] A pointer to VOID.

Return Value

An HRESULT. Possible values include, but are not limited to, those in the following table.

Value	Description
S_OK	Indicates that the operation was successful.

Remarks

You can use the SetLogData method to modify values that IIS will write to a log file. To use this method in an HTTP module, your module should first call the ISendResponseProvider::GetReadyToLogData method to verify that IIS is ready to log information, and then call the ISendResponseProvider::GetLogData method to retrieve a VOID pointer that you will cast to an HTTP_LOG_FIELDS_DATA structure.

Note

The HTTP_LOG_FIELDS_DATA structure is defined in the Http.h header file.

You can use the HTTP_LOG_FIELDS_DATA structure to modify any of the values that IIS is logging (for example, the server name or the client's user-agent string). When you have finished modifying the log values, you use SetLogData to submit your modified values to IIS.

Example

The following code example demonstrates how to create an HTTP module that uses the GetReadyToLogData method to determine whether IIS is ready log information. The module completes the following steps:

Uses the GetLogData method to retrieve an HTTP_LOG_FIELDS_DATA structure.
Uses this structure to retrieve the server name from the log information.
Modifies the server port in the log entry.
Uses the SetLogData method to submit the modified log information to IIS.
Returns the server name to a Web client and then exits.

#define _WINSOCKAPI_
#include <windows.h>
#include <sal.h>
#include <httpserv.h>

// Create the module class.
class MyHttpModule : public CHttpModule
{
public:
    REQUEST_NOTIFICATION_STATUS
    OnSendResponse(
        IN IHttpContext * pHttpContext,
        IN ISendResponseProvider * pProvider
    )
    {
        
        // Retrieve log status.
        if (TRUE == pProvider->GetReadyToLogData())
        {
            // Retrieve log information.
            PHTTP_LOG_FIELDS_DATA pLogData =
                (PHTTP_LOG_FIELDS_DATA) pProvider->GetLogData();
            // Test for an error.
            if (NULL != pLogData)
            {
                // Clear the existing response.
                pHttpContext->GetResponse()->Clear();
                // Set the MIME type to plain text.
                pHttpContext->GetResponse()->SetHeader(
                    HttpHeaderContentType,"text/plain",
                    (USHORT)strlen("text/plain"),TRUE);
                // Return the server name.
                WriteResponseMessage(pHttpContext,
                    "Server name: ",pLogData->ServerName);
                // Modify the port number.
                pLogData->ServerPort = 8080;
                // Set the log data.
                HRESULT hr = pProvider->SetLogData(pLogData);
                // Test for an error.
                if (FAILED(hr))
                {
                    // Set the error status.
                    pProvider->SetErrorStatus( hr );
                    // End additional processing.
                    return RQ_NOTIFICATION_FINISH_REQUEST;
                }
            }
        }
        // Return processing to the pipeline.
        return RQ_NOTIFICATION_CONTINUE;
    }

private:

    // Create a utility method that inserts a name/value pair into the response.
    HRESULT WriteResponseMessage(
        IHttpContext * pHttpContext,
        PCSTR pszName,
        PCSTR pszValue
    )
    {
        // Create an HRESULT to receive return values from methods.
        HRESULT hr;
        
        // Create a data chunk.
        HTTP_DATA_CHUNK dataChunk;
        // Set the chunk to a chunk in memory.
        dataChunk.DataChunkType = HttpDataChunkFromMemory;
        // Buffer for bytes written of data chunk.
        DWORD cbSent;

        // Set the chunk to the first buffer.
        dataChunk.FromMemory.pBuffer =
            (PVOID) pszName;
        // Set the chunk size to the first buffer size.
        dataChunk.FromMemory.BufferLength =
            (USHORT) strlen(pszName);
        // Insert the data chunk into the response.
        hr = pHttpContext->GetResponse()->WriteEntityChunks(
            &dataChunk,1,FALSE,TRUE,&cbSent);
        // Test for an error.
        if (FAILED(hr))
        {
            // Return the error status.
            return hr;
        }

        // Set the chunk to the second buffer.
        dataChunk.FromMemory.pBuffer =
            (PVOID) pszValue;
        // Set the chunk size to the second buffer size.
        dataChunk.FromMemory.BufferLength =
            (USHORT) strlen(pszValue);
        // Insert the data chunk into the response.
        hr = pHttpContext->GetResponse()->WriteEntityChunks(
            &dataChunk,1,FALSE,TRUE,&cbSent);
        // Test for an error.
        if (FAILED(hr))
        {
            // Return the error status.
            return hr;
        }

        // Return a success status.
        return S_OK;
    }
};

// Create the module's class factory.
class MyHttpModuleFactory : public IHttpModuleFactory
{
public:
    HRESULT
    GetHttpModule(
        OUT CHttpModule ** ppModule, 
        IN IModuleAllocator * pAllocator
    )
    {
        UNREFERENCED_PARAMETER( pAllocator );

        // Create a new instance.
        MyHttpModule * pModule = new MyHttpModule;

        // Test for an error.
        if (!pModule)
        {
            // Return an error if the factory cannot create the instance.
            return HRESULT_FROM_WIN32( ERROR_NOT_ENOUGH_MEMORY );
        }
        else
        {
            // Return a pointer to the module.
            *ppModule = pModule;
            pModule = NULL;
            // Return a success status.
            return S_OK;
        }            
    }

    void Terminate()
    {
        // Remove the class from memory.
        delete this;
    }
};

// Create the module's exported registration function.
HRESULT
__stdcall
RegisterModule(
    DWORD dwServerVersion,
    IHttpModuleRegistrationInfo * pModuleInfo,
    IHttpServer * pGlobalInfo
)
{
    UNREFERENCED_PARAMETER( dwServerVersion );
    UNREFERENCED_PARAMETER( pGlobalInfo );

    // Create an HRESULT to receive return values from methods.
    HRESULT hr;

    // Set the request priority.
    hr = pModuleInfo->SetPriorityForRequestNotification(
        RQ_SEND_RESPONSE,PRIORITY_ALIAS_HIGH);

    // Test for an error and exit if necessary.
    if (FAILED(hr))
    {
        return hr;
    }

    // Set the request notifications and exit.
    return pModuleInfo->SetRequestNotifications(
        new MyHttpModuleFactory,
        RQ_SEND_RESPONSE,
        0
    );
}

Your module must export the RegisterModule function. You can export this function by creating a module definition (.def) file for your project, or you can compile the module by using the /EXPORT:RegisterModule switch. For more information, see Walkthrough: Creating a Request-Level HTTP Module By Using Native Code.

You can optionally compile the code by using the __stdcall (/Gz) calling convention instead of explicitly declaring the calling convention for each function.

Requirements

Type	Description
Client	- IIS 7.0 on Windows Vista - IIS 7.5 on Windows 7 - IIS 8.0 on Windows 8 - IIS 10.0 on Windows 10
Server	- IIS 7.0 on Windows Server 2008 - IIS 7.5 on Windows Server 2008 R2 - IIS 8.0 on Windows Server 2012 - IIS 8.5 on Windows Server 2012 R2 - IIS 10.0 on Windows Server 2016
Product	- IIS 7.0, IIS 7.5, IIS 8.0, IIS 8.5, IIS 10.0 - IIS Express 7.5, IIS Express 8.0, IIS Express 10.0
Header	Httpserv.h