C / C++ / MFC

7-May-09 6:06

I use in my program MFC to download files from the internet, and I want to know if it will work through an authenticating proxy server.

This is my CInternetSession object:

m_pInternetSession = new CInternetSession("Microsoft Internet Explorer 5.0");

And this is CInternetSession constructor from MFC sources.

#define PRE_CONFIG_INTERNET_ACCESS  INTERNET_OPEN_TYPE_PRECONFIG

.................................

	/* explicit */ CInternetSession(LPCTSTR pstrAgent = NULL,
		DWORD_PTR dwContext = 1,
		DWORD dwAccessType = PRE_CONFIG_INTERNET_ACCESS,
		LPCTSTR pstrProxyName = NULL,
		LPCTSTR pstrProxyBypass = NULL,
		DWORD dwFlags = 0);

So it uses INTERNET_OPEN_TYPE_PRECONFIG by default.

And this is written about INTERNET_OPEN_TYPE_PRECONFIG in MSDN:
Use INTERNET_OPEN_TYPE_PRECONFIG to instruct your application to retrieve the configuration from the registry

So does that mean that my program will correctly load any proxy settings that were set for internet explorer and how can I check that? I've never really used proxies, so I'm at a loss here.

There is sufficient light for those who desire to see, and there is sufficient darkness for those of a contrary disposition.
Blaise Pascal

Stuart Dootson7-May-09 7:32

7-May-09 7:32

Have you tried it to see if it does work or not?

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

sashoalm7-May-09 22:37

7-May-09 22:37

How can I check if it works? I myself don't connect through a proxy, this issue happens with a client.

Is there any way I can use a public proxy to make a test?

There is sufficient light for those who desire to see, and there is sufficient darkness for those of a contrary disposition.
Blaise Pascal

Stuart Dootson7-May-09 22:42

7-May-09 22:42

sashoalm wrote:
How can I check if it works? I myself don't connect through a proxy, this issue happens with a client.

Is there any way I can use a public proxy to make a test?

I think you can make Fiddler[^] act as a proxy that requires authentication. You could test it with that?

Fiddler's an incredibly useful tool to have anyway if you're doing lower-level web development, as you are - it's like Visual Studio's debugger, but for web traffic!

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

sashoalm8-May-09 0:34

8-May-09 0:34

Thanks for the link. I installed Fiddler, and I see that it has set my connection settings to use proxy at 127.0.0.1:8888, so it should be working. But I couldn't find any option to make it issue authentification challenges (I checked in Tools->Fiddler Options)

There is sufficient light for those who desire to see, and there is sufficient darkness for those of a contrary disposition.
Blaise Pascal

Stuart Dootson8-May-09 2:04

8-May-09 2:04

It might need scripting (if it's possible) - have a look at this page[^]

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

sashoalm8-May-09 4:32

8-May-09 4:32

Thanks for your help, it worked. I now get an auth. request when I start Internet Explorer, and I found where the problem with our app is. Btw it didn't need scripting, there was a menu entry "Rules->Require Proxy Authentification".

There is sufficient light for those who desire to see, and there is sufficient darkness for those of a contrary disposition.
Blaise Pascal

Stuart Dootson8-May-09 4:47

8-May-09 4:47

So there is! Blush | :O

Glad it worked for you!

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

Stuart Dootson7-May-09 22:54

capturing notify messages

7-May-09 22:54

As an alternative to Fiddler, Squid[^] is a well-respected web proxy that (may be) easy to install and configure. It supports authentication (including HTTP Basic and Windows NTLM), so would probably make a good simulation of your customer's scenario (hey - they might use Squid, in which case you could use their configuration to guide you possibly?).

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

kitkat120127-May-09 6:00

kitkat12012

7-May-09 6:00

ok, so i have a dialog, which i'll call CMainDlg.

CMainDlg has a regular CSplitterWnd with two columns.

the splitter has two CWnd derived objects in it, which i'll call CNewWnd

so here's how i created them:

(inside CMainDlg's onInitDialog)

CCreateContext* con = new CCreateContext();<br />
con->m_pNewViewClass = RUNTIME_CLASS(CNewWnd);<br />
<br />
splitter.CreateStatic( this, 1, 2, WS_VISIBLE);<br />
splitter.CreateView(0,0, con->m_pNewViewClass, CSize(200, 200), con);<br />
splitter.CreateView(0,1, con->m_pNewViewClass, CSize(200, 200), con);

that creates the splitters, and the stuff inside them, everything works perfectly, except for the fact that i can't seem to catch the messages from the CNewWnd using ON_NOTIFY

so the problem is, ON_NOTIFY requires the DlgCtrlID like this:
ON_NOTIFY(NM_CLICK, IDD_DLG, func)

but i dont have that value cause the CNewWnd objects are created dynamically

i tried using SetDlgCtrlID() on the CNewWnd objects but it seems to crash the splitter

i also tried sending custom ids using SendMessage but it's not getting caught

(inside CMainDlg)

ON_NOTIFY(NM_CLICK, 15, func)<br />
splitter.GetPane(0, 0)->m_customid = 15;

(inside CNewWnd)
GetOwner->SendMessage(WM_NOTIFY, (WPARAM) m_customid, (LPARAM)hdr);

any suggestions? thanks

Re: capturing notify messages

led mike7-May-09 7:02

led mike

7-May-09 7:02

kitkat12012 wrote:
i can't seem to catch the messages from the CNewWnd using ON_NOTIFY

so the problem is, ON_NOTIFY requires the DlgCtrlID like this:
ON_NOTIFY(NM_CLICK, IDD_DLG, func)

but i dont have that value cause the CNewWnd objects are created dynamically

It's been a while but I think you want to be notified of WM messages from a CView. NM messages are sent from specific controls.

See here[^]

Confusion about object code generated?

lionelcyril7-May-09 5:12

lionelcyril

7-May-09 5:12

When we compile a C/C++ program we get the object code.
Now my doubt is :
When the object code is executed after transferring into the main memory what is it :
1. Is it a PROGRAM or
2. IS it a process....

I got really confused today in my vivas today cause of my examiner....

Eytukan7-May-09 5:20

Eytukan

7-May-09 5:20

A program in execution is called "Process". A program is what you call as .exe. That would also call as an application.
So Program, process, Application all would mean same.

lionelcyril wrote:
When the object code is executed after transferring into the main memory what is it :

Also, You don't execute an object code. Your object code gets through linker to make it executable code. .exe

Starting to think people post kid pics in their profiles because that was the last time they were cute - Jeremy.

«_Superman_»7-May-09 5:22

«_Superman_»

7-May-09 5:22

Another thing to add is that object code cannot be executed.
It has to be linked by a linker into an executable before it can be executed.

«_Superman_»
I love work. It gives me something to do between weekends.

Eytukan7-May-09 5:25

Eytukan

7-May-09 5:25

Oops I was just adding it.

Starting to think people post kid pics in their profiles because that was the last time they were cute - Jeremy.

IWinHttpRequest get_ResponseStream and Bitmap FromStream [modified]

CPallini7-May-09 7:00

CPallini

7-May-09 7:00

When you compile C/C++ sources, usually you obtain an executable (or an application): the object code (usually again) is just an intermediate result.

lionelcyril wrote:
When the object code is executed after transferring into the main memory what is it :
1. Is it a PROGRAM or
2. IS it a process....

Is is a process, i.e. a running executable (or running application).

'Program', on the other hand, has a very broad sense, usually the context qualify better its meaning.
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

J.B.7-May-09 4:54

J.B.

7-May-09 4:54

Hi,

I am writing some code that can download JPEG images from the net (HTTP) and display them on my dialog app.

So far I am able to get the image with IStream interface by using IWinHttpRequest's get_ResponseStream(). But I found myself failing to take the Stream object to load it to GDI+ Bitmap object.

IStream *pStream; // valid Stream object downloaded
if (NULL != pStream)
{
	Bitmap *pGdiBmp = NULL;

	// Rewind IStream.
	LARGE_INTEGER llMove;
	llMove.LowPart = 0;
	llMove.HighPart = 0;
	pStream->Seek(llMove, STREAM_SEEK_SET, NULL);
	pGdiBmp = Bitmap::FromStream(pStream);
}

pGdiBmp is always NULL. I tried to save pStream to disk and the resulted binary is correct JPEG file.

What am I doing wrong here?

Any help would be great.
Thanks in advance.

modified on Thursday, May 7, 2009 11:48 AM

Re: IWinHttpRequest get_ResponseStream and Bitmap FromStream

Stuart Dootson7-May-09 7:28

Re: IWinHttpRequest get_ResponseStream and Bitmap FromStream

7-May-09 7:28

I'd verify that the contents of the stream are a JPEG by loading it into memory using GetHGlobalFromStream followed by a GlobalLock on the HGLOBAL you got back from the first function. Then verify that the memory starts with the string "JFIF".

I used the WinHttp functions to download a JPG and found that the JPG started after the first six bytes of the response (I created a stream on a set of bytes) - I needed to offset the stream by six bytes to get the Bitmap to load:

Gdiplus::Bitmap* LoadBitmapFromUrl(CString const& url)
{
   HINTERNET hInternet = WinHttpOpen(L"hello", WINHTTP_ACCESS_TYPE_DEFAULT_PROXY, WINHTTP_NO_PROXY_NAME, WINHTTP_NO_PROXY_BYPASS, 0);
   if (!hInternet) return 0;
   HINTERNET hConnection = WinHttpConnect(hInternet, L"www.python.org", INTERNET_DEFAULT_PORT, 0);
   if (!hConnection) return 0;
   LPCWSTR types[] = { L"image/jpeg", 0 };
   HINTERNET hRequest = WinHttpOpenRequest(hConnection, L"GET", L"/images/success/standrews.jpg", 0, WINHTTP_NO_REFERER, types, 0);
   if (!hRequest) return 0;
   if (!WinHttpSendRequest(hRequest, WINHTTP_NO_ADDITIONAL_HEADERS, 0, WINHTTP_NO_REQUEST_DATA, 0, 0, 0)) return 0;
   if (!WinHttpReceiveResponse(hRequest, 0)) return 0;
   HGLOBAL gblBuffer = GlobalAlloc(0, 1<<20);
   LPBYTE buffer = (LPBYTE)GlobalLock(gblBuffer);
   DWORD nBytesRead;
   if (!WinHttpReadData(hRequest, buffer, 1<<20, &nBytesRead)) return 0;
   IStream* pStream = 0;
   CreateStreamOnHGlobal(gblBuffer, FALSE, &pStream);
   ULARGE_INTEGER size; size.QuadPart = nBytesRead;
   pStream->SetSize(size);
   LARGE_INTEGER offset; offset.QuadPart = 6;
   pStream->Seek(offset, STREAM_SEEK_SET, 0);
   return new Gdiplus::Bitmap(pStream, FALSE);
}

(Please ignore the memory leak - I couldn't be bothered to tidy up - it's not production code Smile | :)

)

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

J.B.7-May-09 20:58

J.B.

7-May-09 20:58

Dear Stuart,

Thanks for the help. I'd get invalid image if I offset the stream by 6 bytes. I am not sure why it worked in your case.

Anyway, I found where my problem was. I have that code running outside of GDI+ library init scope. After I moved the following init code to CWinApp::InitInstance(), it worked fine.

// Initialize GDI+.
Gdiplus::GdiplusStartupInput gdiplusStartupInput;
Gdiplus::GdiplusStartup(&m_gdiplusToken, &gdiplusStartupInput, NULL);

Re: IWinHttpRequest get_ResponseStream and Bitmap FromStream

Stuart Dootson7-May-09 21:47

Re: IWinHttpRequest get_ResponseStream and Bitmap FromStream

7-May-09 21:47

I took it as a given that the GDI+ stuff was right - more fool me Smile | :)

J.B. wrote:
I'd get invalid image if I offset the stream by 6 bytes. I am not sure why it worked in your case.

Maybe because I was using WinHttpReadData rather than getting a stream directly from the IWinHttpRequest object.

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

J.B.7-May-09 22:50

J.B.

7-May-09 22:50

Stuart Dootson wrote:
Maybe because I was using WinHttpReadData rather than getting a stream directly from the IWinHttpRequest object.

That'd be strange, because I checked the my Stream buffer and it had the same pattern as you described - after first 6 bytes, it comes with "JFIF"

FF D8 FF E0 00 10 4A 46 49 46
                  J  F  I  F

Re: IWinHttpRequest get_ResponseStream and Bitmap FromStream

Stuart Dootson7-May-09 23:04