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Calling an HTTP server from MFC, using POST

Posted on 2009-04-07
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Last Modified: 2013-12-03
I have to modify existing code (shown below).
The existing code queries an HTTP server using a simple GET (Actual URL is not shown)
Then starts to download the response (First few lines of the download loop are shown below)
The new code must use a POST request, and otherwise do the same.
Where do I tell the server
1)This is a POST, not a GET request,
2)Where is the POSTed buffer supposed to show in the request?
3)Anything else about the HTTP headers matters if it's a POST, not a GET?, if so please tell.

...

	HINTERNET  hConnect = NULL;

	HINTERNET  hSession = NULL;

	BYTE *pBuffer;

	hSession = InternetOpen("SPLOOKUP",  INTERNET_OPEN_TYPE_PRECONFIG,NULL, NULL, 0);

	if(hSession == NULL ){

		delete pParam;

		return;

	}

	hConnect = InternetOpenUrl(hSession,  csLink ,NULL, 0, INTERNET_FLAG_RELOAD, 0);  

	if(hConnect == NULL ){

		InternetCloseHandle(hSession);

		delete pParam;

		return;

	}
 

	char szSizeBuffer[32];

	DWORD dwLengthSizeBuffer = sizeof(szSizeBuffer); 

	BOOL bQuery = ::HttpQueryInfo(hConnect,HTTP_QUERY_CONTENT_LENGTH, szSizeBuffer, &dwLengthSizeBuffer, NULL) ;

	DWORD dwFileSize=atol(szSizeBuffer);

	BOOL bRet = TRUE;

	BOOL bCanceled = FALSE;

	CString csInBuffer;
 

	static const iMAXSIZE = 50000;
 

	while(true){

		DWORD dwNumberOfBytesAvailable = 0;

		InternetQueryDataAvailable(hConnect, &dwNumberOfBytesAvailable, 0, 0);

		pBuffer = new BYTE[dwNumberOfBytesAvailable+1];

		DWORD dwBytesRead = 0;

		bRet = InternetReadFile(hConnect,(LPVOID)pBuffer,dwNumberOfBytesAvailable,  &dwBytesRead);  

...

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Question by:yossikally
3 Comments
 
LVL 30

Expert Comment

by:Zoppo
ID: 24092089
Hi yossikally,

I'm not quite expert for this, but in MSDN I found no way to do this with InternetOpenUrl.

I think you'll have to use InternetConnect to initialize the connection after InternetOpen and then use HttpSendRequestEx, but unfortunateley up to now the only sample code I found seems to have a bug (http://www.codeguru.com/forum/showthread.php?p=1194917) - but I guess it shouldn't be to difficult to find other samples.

Hope that helps,

ZOPPO
0
 

Author Comment

by:yossikally
ID: 24092443
Thanks Zoppo

Aside from the error, I couln't quite understand from the example how and where I send the request headers along with the request.

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LVL 2

Accepted Solution

by:
crystyce earned 500 total points
ID: 24094666
Maybe this example helps
	CString url_data = "I'm posting this by http";
 

	HINTERNET hInternetSession;

	hInternetSession = ::InternetOpen("Serv",INTERNET_OPEN_TYPE_PRECONFIG,NULL,NULL,0 );
 

	if (hInternetSession==NULL)

		return 0;
 

	HINTERNET hFile,hRequest;

	

	hFile = InternetConnect(hInternetSession,server,port,NULL,NULL,INTERNET_SERVICE_HTTP,0,(DWORD_PTR)&dwContext);

	if (hFile==NULL)

	{

		InternetCloseHandle(hInternetSession);

		return 0;

	}
 

	

	DWORD dwFlags=INTERNET_FLAG_NO_AUTH|INTERNET_FLAG_PRAGMA_NOCACHE|INTERNET_FLAG_RELOAD;

	

	hRequest = HttpOpenRequest(hFile,"POST","",NULL,NULL,NULL,dwFlags,(DWORD_PTR)&dwContext);
 

	if (hFile==NULL)

	{

		InternetCloseHandle(hFile);

		InternetCloseHandle(hInternetSession);

		return 0;

	}
 

	BOOL ret = HttpSendRequest(hRequest,NULL,0,(LPVOID)(LPCTSTR)url_data,url_data.GetLength());

	if (!ret)

	{

		InternetCloseHandle(hRequest);

		InternetCloseHandle(hFile);

		InternetCloseHandle(hInternetSession);

		return 0;

	}

	

	while (...)

	{

		status = InternetReadFile(hRequest,buf,buffer_size,&dwBytes);

	}

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