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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
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3 Comments
 
LVL 31

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 2000 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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