uploading files using httpSendRequest c++ - asp.net

Question

I am trying to send a file to HTTP server via POST request (c++ and winapi), steps:
// Read file into "buff" and file size into "buffSize"
....
....
....
HINTERNET internetRoot;
HINTERNET httpSession;
HINTERNET httpRequest;
internetRoot = InternetOpen(agent_info, INTERNET_OPEN_TYPE_DIRECT, NULL, NULL, NULL);
//Connecting to the http server
httpSession = InternetConnect(internetRoot, IP,PORT_NUMBER, NULL, NULL, INTERNET_SERVICE_HTTP, NULL, NULL);
//Creating a new HTTP POST request to the default resource on the server
httpRequest = HttpOpenRequest(httpSession, TEXT("POST"), TEXT("/Post.aspx"), NULL, NULL, NULL, INTERNET_FLAG_RELOAD | INTERNET_FLAG_NO_CACHE_WRITE, NULL);
//Send POST request
HttpSendRequest(httpRequest, NULL, NULL, buff, buffSize);
//Closing handles...
In server I am recieving the file using this code (asp.net)
Stream httpStream;
try
{
httpStream = request.RequestContext.HttpContext.Request.InputStream;
}
catch (HttpException)
{
return;
}
byte[] tmp = new byte[httpStream.Length];
int bytesRead = httpStream.Read(tmp, 0, 1024 * 1024);
int totalBytesRead = bytesRead;
while (bytesRead > 0)
{
bytesRead = httpStream.Read(tmp, totalBytesRead, 1024 * 1024);
totalBytesRead += bytesRead;
}
httpStream.Close();
httpStream.Dispose();
//Save "tmp" to file...
I can send large files on local server (visual studio asp server), but I cannot send files over 1 MB to internet server. (HttpOpenRequest is failing)
is there a better way to upload files?

Answer 1

Caveat: My Wininet is very rusty these days.
I wonder whether you ought to be setting the "Content-Length" header yourself. Your code seems to assume that either a) you are making a HTTP/1.0 request or b) that HttpSendRequest will add the header for your (which I don't think it does).
Either way without the server being told how big the incoming request is the default configuration of IIS will reject it if it can't determine the request size itself quickly.
My guess is if you use the lpszHeaders and dwHeadersLength parameters of the HttpSendRequest function to include the appropriate "Content-Length" header the problem will be resolved.

Answer 2

What error do you receive? I mean what does GetLastError() returns? If you send file 800KB then it works OK? I dont really see how because HttpOpenRequest does not know about size of the data.
Maybe it timeouts? But this would mean that HttpSendRequest actually fails. It might buffer all data but since size is huge, then it takes more time than timeout allows.
use following code to query current timeouts (in ms):
InternetQueryOption(h, INTERNET_OPTION_RECEIVE_TIMEOUT, &dwReceiveTimeOut, sizeof(dwReceiveTimeOut));
InternetQueryOption(h, INTERNET_OPTION_SEND_TIMEOUT, &dwSendTimeOut, sizeof(dwSendTimeOut));
and following to set new ones:
InternetSetOption(h, INTERNET_OPTION_RECEIVE_TIMEOUT, &dwNewReceiveTimeOut, sizeof(dwNewReceiveTimeOut));
InternetSetOption(h, INTERNET_OPTION_SEND_TIMEOUT, &dwNewSendTimeOut, sizeof(dwNewSendTimeOut));