How to download a file with WinHTTP in C/C++?

Question

I know how to download an html/txt page. For example :

//Variables 
DWORD dwSize = 0;
DWORD dwDownloaded = 0;
LPSTR pszOutBuffer;
vector <string>  vFileContent;
BOOL  bResults = FALSE;
HINTERNET  hSession = NULL, 
           hConnect = NULL,
           hRequest = NULL;

// Use WinHttpOpen to obtain a session handle.
hSession = WinHttpOpen( L"WinHTTP Example/1.0",  
                        WINHTTP_ACCESS_TYPE_DEFAULT_PROXY,
                        WINHTTP_NO_PROXY_NAME, 
                        WINHTTP_NO_PROXY_BYPASS, 0);

// Specify an HTTP server.
if (hSession)
    hConnect = WinHttpConnect( hSession, L"nytimes.com",
                               INTERNET_DEFAULT_HTTP_PORT, 0);

// Create an HTTP request handle.
if (hConnect)
    hRequest = WinHttpOpenRequest( hConnect, L"GET", L"/ref/multimedia/podcasts.html",
                                   NULL, WINHTTP_NO_REFERER, 
                                   NULL, 
                                   NULL);

// Send a request.
if (hRequest)
    bResults = WinHttpSendRequest( hRequest,
                                   WINHTTP_NO_ADDITIONAL_HEADERS,
                                   0, WINHTTP_NO_REQUEST_DATA, 0, 
                                   0, 0);


// End the request.
if (bResults)
    bResults = WinHttpReceiveResponse( hRequest, NULL);

// Keep checking for data until there is nothing left.
if (bResults)
    do 
    {

        // Check for available data.
        dwSize = 0;
        if (!WinHttpQueryDataAvailable( hRequest, &dwSize))
            printf( "Error %u in WinHttpQueryDataAvailable.\n",
                    GetLastError());

        // Allocate space for the buffer.
        pszOutBuffer = new char[dwSize+1];
        if (!pszOutBuffer)
        {
            printf("Out of memory\n");
            dwSize=0;
        }
        else
        {
            // Read the Data.
            ZeroMemory(pszOutBuffer, dwSize+1);

            if (!WinHttpReadData( hRequest, (LPVOID)pszOutBuffer, 
                                  dwSize, &dwDownloaded))
            {
                printf( "Error %u in WinHttpReadData.\n", 
                        GetLastError());
            }
            else
            {
                        printf("%s", pszOutBuffer);
                            // Data in vFileContent
                vFileContent.push_back(pszOutBuffer);
            }

            // Free the memory allocated to the buffer.
            delete [] pszOutBuffer;
        }

    } while (dwSize>0);


// Report any errors.
if (!bResults)
    printf("Error %d has occurred.\n",GetLastError());

// Close any open handles.
if (hRequest) WinHttpCloseHandle(hRequest);
if (hConnect) WinHttpCloseHandle(hConnect);
if (hSession) WinHttpCloseHandle(hSession);

// Write vFileContent to file
ofstream out("test.txt",ios::binary);
for (int i = 0; i < (int) vFileContent.size();i++)
out << vFileContent[i];
out.close();

When I try to download a picture, I get only the first lines of the file and no error message. The problem seems related to this parameter (ppwszAcceptTypes) in WinHttpOpenRequest Function.

link text

Solution

Looks like this thread on MSDN is the same and has the solution

http://social.msdn.microsoft.com/forums/en-US/vclanguage/thread/45ccd91c-6794-4f9b-8f4f-865c76cc146d

Comments

[Admin]

I've read this thread before, but the solution (opening the file in binary mode) didn't work for me. But I've just retried it, this time using C, not C++, and it works. So ofstream is not working with WinHttp, as far as I can tell.