Httpqueryinfo() - access violation reading location 0x00000800 [SOLVED]

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I expect a response from the server after sending it some data with HttpSendRequest() function. I want to read the response, I call the HttpQueryInfo() function, and the debugger stops with Exception thrown ... Access violation reading location 0x00000800 message. I'd use the buffer array for the response, and I assume the problem is somewhere there. I don't get any errors with the GetLastError() function.

else if (method == _T("POST")) {
		LPCTSTR header = _T("Content-Type: text/html\nCustomers");
		BOOL hHttpSendReq = HttpSendRequest(hHttpOpenReq, NULL, NULL, toSend, strlen(toSend));
		if (!hHttpSendReq) {
			DWORD ErrorNum = GetLastError();
			std::cout << "HttpSendRequest() error No: " << ErrorNum;
			InternetCloseHandle(hHttpOpenReq);
			InternetCloseHandle(hIntConnect);
			InternetCloseHandle(hIntOpen);
			getchar();
			return 0;
		}
		char buffer[2048];
		if (HttpQueryInfo(hHttpOpenReq, HTTP_QUERY_RAW_HEADERS_CRLF, buffer, (LPDWORD)2048, NULL)) {
		
		}
		else {
			cout << "GetLastError:"<<GetLastError();
		}

In the debugger 'buffer' is shown red, and there is no content in there, only funny characters.
Any idea? Thanks.

What I have tried:

I don't know where to look, I checked some examples on the net, but they look similar. I also changed the flags (arguments), but I don't think the problem is there anyway.

Posted 22-Feb-18 12:30pm

m_smith

Updated 11-Mar-18 23:31pm

v2

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m_smith · Answer 1 · 2018-02-22T13:10:00

Solution 1

I don't know exactly what the problem was, but now it works :)

char buffer[4096];
		DWORD bufferSize = 4096;
		if (HttpQueryInfo(hHttpOpenReq, HTTP_QUERY_RAW_HEADERS_CRLF, (LPVOID)buffer, &bufferSize, NULL)) {
			cout << "buffer:" << buffer;
		}

Posted 22-Feb-18 13:10pm

m_smith