Comments on: On USB Driver Coding #7 http://evilcodecave.wordpress.com/2007/11/30/on-usb-driver-coding-7/ Just another RCE Weblog Fri, 12 Mar 2010 00:45:24 +0000 hourly 1 http://wordpress.com/ By: Alex http://evilcodecave.wordpress.com/2007/11/30/on-usb-driver-coding-7/#comment-737 Sun, 28 Jun 2009 15:10:56 +0000 http://evilcodecave.wordpress.com/2007/11/30/on-usb-driver-coding-7/#comment-737 Hi dude! I’m quite surprised somebody really decided to make such a review of a USB lower filter-driver. I’m doing the same just now (except it’s in russian) and have some particular questions about it.
First of all i don’t understand, why you don’t use the FilterDispatchAny routine in your DriverEntry function, but still have it for some reasons. In the sources i have (it’s Benoit’s driver-filter, http://benoit.papillault.free.fr/index.php.en ) this routine is actually used (for every major function, except IRP_MJ_PNP and IRP_MJ_POWER).
The second thing i didn’t get is about the DispatchPnP routine. IRP_MJ_PNP is actually set to be handled by the FilterDispatchPnP routine, but FilterDispatchAny has the branch to handle IRP_MJ_PNP too. Why???
Next, I didn’t get it, where my driver actually is??? It’s said to be lower-filter and installed as lower-filter, but sources say FDO appears to be our LOWER device, so the truth is that my driver is UPPER-filter driver. How is it possible? May be my understanding of WMD is inaccurate?
And finally, WHY IN THE WORLD we have to hook FDO dispatch tables just because of 2 IRP function codes??? Why can we not handle them by our FiDO?

P.S. Thanks a lot for your work. I think many people would appreciate and find it useful.

P.P.S. Can you suggest some literature or links about the topic?

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