IHttpRequest::InsertEntityBody Method

Article
05/20/2022

Inserts a new entity body into the existing HTTP request body.

Syntax

virtual HRESULT InsertEntityBody(  
   IN VOID* pvBuffer,  
   IN DWORD cbBuffer  
) = 0;

Parameters

pvBuffer
[IN] A pointer to a VOID buffer that contains the request entity body.

cbBuffer
[IN] A DWORD that contains the size, in bytes, of the buffer.

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

The InsertEntityBody method inserts the entity body that is pointed to by the pvBuffer parameter into the HTTP request entity body.

Note

The insertion point of the new entity body is before any remaining unread entity body that can be subsequently retrieved from the Web client.

Important

IIS does not make a copy of the entity body buffer. Your module's entity buffer must be preserved until the end of the request.

This method does not update the Content-Length header value. A module that uses this method must update the Content-Length separately.

Example

The following code example demonstrates how create an HTTP module that calls the IHttpContext::AllocateRequestMemory method to allocate a 1-KB buffer. The module then copies the string "Hello World" into the buffer. Finally, the module calls the InsertEntityBody method to replace the preloaded HTTP request entity body with the buffer and then exits.

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

// NOTE - Data needs to be passed to this module, e.g. a POST request, or it will not appear to return anything.

// Create the module class.
class MyHttpModule : public CHttpModule
{
public:
    REQUEST_NOTIFICATION_STATUS
    OnBeginRequest(
        IN IHttpContext * pHttpContext,
        IN IHttpEventProvider * pProvider
    )
    {
        // Create an HRESULT to receive return values from methods.
        HRESULT hr;

        // Allocate a 1K buffer.
        DWORD cbBuffer = 1024;
        void * pvBuffer = pHttpContext->AllocateRequestMemory(cbBuffer);
        
        // Test for an error.
        if (NULL == pvBuffer)
        {
            // Set the error status.
            pProvider->SetErrorStatus(
                HRESULT_FROM_WIN32(ERROR_NOT_ENOUGH_MEMORY));
            // End additional processing.
            return RQ_NOTIFICATION_FINISH_REQUEST;
        }
        
        // Copy a string into the buffer.
        strcpy_s((char*)pvBuffer,cbBuffer,"Hello world!");
        // Insert the entity body into the buffer.
        hr = pHttpContext->GetRequest()->InsertEntityBody(
            pvBuffer,(DWORD)strlen((char*)pvBuffer));

        // 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;
    }
};

// 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 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

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