Fooling Around

Although I personally have no experience with tricky DirectShow filters that decide on possibility of connection not only looking at media type and other capabilities, there has been a number of cases mentioned that certain video decoders will only connect to renderers or video renderers in order to avoid interception of decoded data.

It was recently mentioned that one of such filters checked Misc Flags obtained through IAMFilterMiscFlags interface to make sure it is connected to renderer downstream. Before we proceed, let us make it clear that it is silly and can only protect from beginner, a complete newbie. At the very least it should have checked peer filter’s CLSID and compare against white list of stock video renderer: Video Renderer, Video Mixing Rendeder 7, Video Mixing Rendeder 9, Enhanced Video Renderer. A custom video renderer or even just a transformation filter with a renderer flag would be able to receive decoded data and make it available for any further processing.

What I am going to do is to take Sample Grabber Filter as a base and make a new filter from it which will only connect to renderer (it will check the flags as described above). Then another filter, which will also use Sample Grabber Filter base, will accurately fool the first one and connect to output of the first filter and will render video to complete the graph.

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WinHttpCrackUrl and WinHttpCreateUrl API functions are breaking URL string into components and recompose back to string. There was a mess with passwords and security issues since when putting password into URL is no more acceptable. Experienced users might remember the times when URL could embed password, e.g. ftp://john:mysecretpassword@host.com/path. Password is lo longer accepted by major applications in a typed in string and no more allowed by updated RFC 3986 “Uniform Resource Identifier (URI): Generic Syntax”:

3.2.1.  User Information

   The userinfo subcomponent may consist of a user name and, optionally,
   scheme-specific information about how to gain authorization to access
   the resource.  The user information, if present, is followed by a
   commercial at-sign ("@") that delimits it from the host.

      userinfo    = *( unreserved / pct-encoded / sub-delims / ":" )

   Use of the format "user:password" in the userinfo field is
   deprecated.  Applications should not render as clear text any data
   after the first colon (":") character found within a userinfo
   subcomponent unless the data after the colon is the empty string
   (indicating no password).

What if we don’t have URLs typed in? But it still convenient to keep password as a part of URL? Luckily there is such thing as compatibility, so we can rely on WinHTTP subsystem to process passwords for us. The problem however is escapement. The most tricky is that it is not a bug, it is documented but is unintuitive. The cracking part would unescape all components if ICU_DECODE flag is provided. The composing part however will only escape (ICU_ESCAPE) the part to the right from port number (whether it is specified or expected to be)!

For example (see source code below):

g_ppszUrls[3] http://user:pa%40ss@site.com/path?name=value%20%2F%3A%40
.lpszScheme http
.nScheme 1
.lpszHostName site.com
.nPort 80
.lpszUserName user
.lpszPassword pa@ss
.lpszUrlPath /path
.lpszExtraInfo ?name=value /:@
pszUrl http://user:pa@ss@site.com/path?name=value /:@
pszUrl (ICU_ESCAPE) http://user:pa@ss@site.com/path?name=value%20/:@

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Longman Dictionary Online updated their website and changed HTTP request syntax, so search plugin for Firefox requires update. Here is the updated Longman Dictionary of Contemporary English Search Plugin for FireFox.

A simple question being asked all over again. Given IBasicVideo, IBasicVideo2, IVMRWindowlessControl or IVMRWindowlessControl9, how to save image to file? It is easy. It is a bit easier with IBasicVideo because it is possible to query this interface directly from graph’s interface, such as  IGraphBuilder, and the call will be forwarded to video renderer. This code assumes internal bitmap format is non-paletted, which I believe is always the case.

LONG nBufferSize = 0;
ATLENSURE_SUCCEEDED(pBasicVideo->GetCurrentImage(&nBufferSize, NULL));
CHeapPtr<BITMAPINFO> pBitmapInfo;
ATLENSURE_THROW(pBitmapInfo.AllocateBytes(nBufferSize), E_OUTOFMEMORY);
ATLENSURE_SUCCEEDED(pBasicVideo->GetCurrentImage(&nBufferSize, (LONG*) (BITMAPINFO*) pBitmapInfo));
const BYTE* pnData = (const BYTE*) (&pBitmapInfo->bmiHeader + 1);
// NOTE: You might wish to handle <=8 bpp bitmaps here
ATLASSERT(pBitmapInfo->bmiHeader.biBitCount > 8);
ATLASSERT(pBitmapInfo->bmiHeader.biCompression == BI_RGB);
ATLASSERT(pBitmapInfo->bmiHeader.biSizeImage);
BITMAPFILEHEADER BitmapFileHeader;
ZeroMemory(&BitmapFileHeader, sizeof BitmapFileHeader);
BitmapFileHeader.bfType = 'MB';
BitmapFileHeader.bfSize = (DWORD) (sizeof (BITMAPFILEHEADER) + pBitmapInfo->bmiHeader.biSize + pBitmapInfo->bmiHeader.biSizeImage);
BitmapFileHeader.bfOffBits = (DWORD) (sizeof (BITMAPFILEHEADER) + pBitmapInfo->bmiHeader.biSize);
ATLENSURE_SUCCEEDED(File.Write(&BitmapFileHeader, sizeof BitmapFileHeader));
ATLENSURE_SUCCEEDED(File.Write(&pBitmapInfo->bmiHeader, pBitmapInfo->bmiHeader.biSize));
ATLENSURE_SUCCEEDED(File.Write(pnData, (DWORD) pBitmapInfo->bmiHeader.biSizeImage));

ATL regular expression code adds dump/debug capabilities with ATL_REGEXP_DUMP preprocessor definition defined (undocumented). Dump output is directed to stdout, so if the application is not console, it has to be redirected in advance, e.g. into a $(BinaryPath)$(BinaryName)-atlrx.h file.

	CAtlRegExp<> Expression; LPCTSTR pszPattern; BOOL bCaseSensitive;
#if defined(ATL_REGEXP_DUMP)
	REParseError Error = Expression.Parse(pszPattern, bCaseSensitive);
	if(Error != REPARSE_ERROR_OK)
	{
		FILE* pStream = NULL;
		if(!GetStdHandle(STD_OUTPUT_HANDLE))
		{
			TCHAR pszPath[MAX_PATH] = { 0 };
			ATLVERIFY(GetModuleFileName(_AtlBaseModule.GetModuleInstance(), pszPath, _countof(pszPath)));
			RemoveExtension(pszPath); // ATLPath::
			_tcscat_s(pszPath, _countof(pszPath), _T("-atlrx.txt"));
			ATLVERIFY(freopen_s(&pStream, CStringA(pszPath), "w", stdout) == 0);
		}
		_tprintf(_T("Error %d\n"), Error);
		Expression.Dump();
		if(pStream)
			ATLVERIFY(fclose(pStream) == 0);
		ATLASSERT(FALSE); // Break into debugger
	}
#else
	ATLVERIFY(Expression.Parse(pszPattern, bCaseSensitive) == REPARSE_ERROR_OK);
#endif // defined(ATL_REGEXP_DUMP)

There is also ATLRX_DEBUG definition, which enables other debug capabilities. CAtlRegExp object is given a virtual function OnDebugEvent through which it prints comments on CAtlRegExp::Match process, which can be also redirected to file similar way.

Can there be any justification for a completely custom GUI replacing standard caption, buttons etc. and imitating Vista look on Windows XP? Vista look, but with unusual custom controls and still with a jerky Windows 3.11 style font (see prompt for installation path below).

I was about to write that unlike previous versions of Nokia PC Suite, this one at least does the very first thing it is expected to do… but nope, it crashed on… viewing contacts! And it crashes every time soon after contacts browsing is opened!

OK, this might be a “little glitch”, but the Suite is still losing USB cable connections just like it has been doing for a long long time, even when it did not yet have Vista look…

How many Windows processes is necessary for this type of application? I left Bluetooth and Infrared disabled as unneeded. Service context: ServiceLayer.exe which started NclMSBTSrv.exe, NclUSBSrv.exe, NclRSSrv.exe (thanks, because there is 4 more .exes in this Transports subdirectory); Desktop: PCSuite.exe and an application for any major task: ContentCopier.exe, ConnectionManager.exe, CommunicationCentre.exe. It makes an impression I have installed another operating system on top of Windows. I never thought that communication with a cellular phone might be such complex task, which requires so many applications started.

Nokia’s service is “ServiceLayer”, display name “ServiceLayer”, service description is missing…

How did they come to this software design? To implement custom look and feel, fully customized GUI and just not provide any descriptive name for the service, which is by the way starting automatically (well, service startup is Manual, but user applications auto-start by default and would start the service) and keeps bloating system even when the Suite is not being used.

Given a DirectShow filter graph, what media samples are being sent through particular graph point? DumpMediaSamples utility gives a fast answer to this question. It prints out connection media type details (with details of VIDEOINFOHEADER, VIDEOINFOHEADER2 and WAVEFORMATEX structures corresponding to FORMAT_VideoInfo, FORMAT_VideoInfo2 and FORMAT_WaveFormatEx format types) and IMediaSample details obtained through AM_SAMPLE2_PROPERTIES structure.

First of all, it is necessary to create a graph of interest using GraphEdit utility. At the point of interest it is necessary to insert [an uninitialized] Sample Grabber Filter with the filter name “SampleGrabber” (this is the default name but if you add second filter which will be given a different name and remove first filter then, the utility would fail).

The graph may look like this:

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