IScriptMapInfo::GetRequiredAccess Method

Article
03/09/2018

Retrieves the required-access setting for the script processor.

Syntax

virtual DWORD GetRequiredAccess(  
   VOID  
) const = 0;

Parameters

This method takes no parameters.

Return Value

A DWORD that contains the required-access setting for the script processor.

Remarks

The GetRequiredAccess method retrieves the requireAccess attribute for a request handler that is located in the <handlers> section of the ApplicationHost.config file. This attribute contains the type of access (for example, read, write, and so on) that the request handler requires. The following values for the required-access setting are defined in the Schema.xml file for IIS:

<attribute name="requireAccess" type="enum" defaultValue="Script">  
   <enum name="None" value="0" />  
   <enum name="Read" value="1" />  
   <enum name="Write" value="2" />  
   <enum name="Script" value="3" />  
   <enum name="Execute" value="4" />  
</attribute>

For example, when a client requests a file that is processed by the static file handler, the required-access value is 1, because the static file handler requires read-only access by default. A request for an Internet Server API (ISAPI) DLL, however, will return a value of 4, because execute access is required.

Example

The following code example demonstrates how to use the IHttpContext::GetScriptMap method to create an HTTP module that retrieves a pointer to an IScriptMapInfo interface. The example then uses the GetRequiredAccess method to retrieve the required-access setting for the request handler that is processing the current request. The module converts the required-access setting to a string, returns the string 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
    OnPostMapRequestHandler(
        IN IHttpContext * pHttpContext,
        IN IHttpEventProvider * pProvider
    )
    {
        UNREFERENCED_PARAMETER( pProvider );

        // Retrieve the IScriptMapInfo interface.
        IScriptMapInfo * pScriptMapInfo = pHttpContext->GetScriptMap();

        // Test for an error.
        if (NULL != pScriptMapInfo)
        {
            // Clear the existing response.
            pHttpContext->GetResponse()->Clear();
            // Set the MIME type to plain text.
            pHttpContext->GetResponse()->SetHeader(
                HttpHeaderContentType,"text/plain",
                10,TRUE);

            // Create an array of required access strings.
            const char * szRequiredAccess[5] =
                {"None","Read","Write","Script","Execute"};

            // Retrieve the required access setting.
            DWORD dwRequiredAccess = pScriptMapInfo->GetRequiredAccess();

            // Test if the required access is within the bounds of the array.
            if ( dwRequiredAccess < 5 )
            {
                // Return the required access setting to the client.
                WriteResponseMessage(pHttpContext,
                    "Required access: ",szRequiredAccess[dwRequiredAccess]);
            }
            else
            {
                // Return an unspecified access setting to the client.
                WriteResponseMessage(pHttpContext,
                    "Required access: ","Unspecified");
            }

            // 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,
        0,
        RQ_MAP_REQUEST_HANDLER
    );
}

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 Technical Preview
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

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