IHttpContext::MapHandler Method

Article
06/14/2022

Maps a handler for the specified URL and HTTP verb on a site.

Syntax

virtual HRESULT MapHandler(  
    DWORD               dwSiteId,  
    PCWSTR              pszSiteName,  
    PCWSTR              pszUrl,  
    PCSTR               pszVerb,  
    IScriptMapInfo **   ppScriptMap,  
    BOOL                fIgnoreWildcardMappings  
) = 0;

Parameters

dwSiteId
[IN] The ID of the site that contains the URL for mapping.

pszSiteName
[IN] A pointer to a string that contains the site name for the target URL.

pszUrl
[IN] A pointer to a string that contains the relative URL for mapping.

pszVerb
[IN] A pointer to a string that contains the HTTP verb for mapping.

ppScriptMap
[OUT] A pointer to the IScriptMapInfo interface that contains details for the selected script map.

fIgnoreWildcardMappings
[IN] true to ignore wildcard mapping; otherwise, false.

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.
ERROR_NOT_ENOUGH_MEMORY	Indicates that there is insufficient memory to perform the operation.

Remarks

The IScriptMapInfo interface is valid to use for the lifetime of the IHttpContext interface.

Example

The following code example demonstrates how to use the MapHandler method to create an HTTP module that returns.

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

// Create the module class.
class MyHttpModule : public CHttpModule
{
public:
    REQUEST_NOTIFICATION_STATUS
    OnBeginRequest(
        IN IHttpContext * pHttpContext,
        IN IHttpEventProvider * pProvider
    )
    {
        UNREFERENCED_PARAMETER( pProvider );

        // Retrieve a pointer to the request.
        IHttpRequest * pHttpRequest = pHttpContext->GetRequest();

        // Test for an error.
        if (pHttpRequest != NULL)
        {
            // Length of the returned path.
            DWORD cbPhysicalPath = 0;
            
            // Get the length of the mapped path.
            pHttpContext->MapPath(L"/",NULL,&cbPhysicalPath);
            
            // Allocate space to store the path.
            PWSTR pwszPhysicalPath =
                (PWSTR) pHttpContext->AllocateRequestMemory(cbPhysicalPath+1);
            PSTR pszPhysicalPath  =
                (PSTR) pHttpContext->AllocateRequestMemory(cbPhysicalPath+1);
            
            // Test for an error.
            if ((pwszPhysicalPath==NULL) || (pszPhysicalPath==NULL))
            {
                // Set the error status.
                pHttpContext->GetResponse()->SetStatus(500,"Server Error",0,
                    HRESULT_FROM_WIN32(ERROR_NOT_ENOUGH_MEMORY));
                // End additional processing.
                return RQ_NOTIFICATION_FINISH_REQUEST;
            }
            
            // Retrieve the mapped path.
            pHttpContext->MapPath(L"/",pwszPhysicalPath,&cbPhysicalPath);
            
            // Convert the WCHAR string to a CHAR string.
            wcstombs_s((size_t*)&cbPhysicalPath,pszPhysicalPath,
                cbPhysicalPath,pwszPhysicalPath,cbPhysicalPath);
            
            // 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 path information.
            WriteResponseMessage(pHttpContext,
                "Path: ",pszPhysicalPath);

            // 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 );

    // Set the request notifications and exit.
    return pModuleInfo->SetRequestNotifications(
        new MyHttpModuleFactory,
        RQ_BEGIN_REQUEST,
        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 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