chip@ateng.ateng.com (Chip Salzenberg) (05/18/89)
I've become interested in the use of "redirectors" in extending MS-DOS's
idea of a file system. Essentially, there are two ways to make MS-DOS
network:
A network SHELL intercepts interrupt 21H, notices requests for access to
virtual drives, and performs the requested action without MS-DOS ever
knowing what happened.
A network REDIRECTOR intercepts an MS-DOS interrupt intended
specifically for network extensions. This interrupt is called at
strategic points in the processing of file requests, and gives the
network extension a chance to do its thing.
Now, I'm sure that given enough time (:-)) I could write a shell, but I'd
much rather write a redirector. The only problem is that Microsoft doesn't
release info about how to do it! Their reason becomes clear when you realize
that they license their for mucho bucks.
So: Does anyone out there know where redirectors hook in? Even a solid
lead on an interrupt number will gain my eternal gratitude.
(Well, I'll kiss your feet, anyway.)
--
Chip Salzenberg <chip@ateng.com> or <uunet!ateng!chip>
A T Engineering Me? Speak for my company? Surely you jest!
"It's no good. They're tapping the lines."chip@ateng.ateng.com (Chip Salzenberg) (05/20/89)
According to kjeld@iesd.dk (Kjeld Flarup): >According to chip@ateng.ateng.com (Chip Salzenberg): >>I've become interested in the use of "redirectors" in extending MS-DOS's >>idea of a file system. > > Instead you should keep at int 021H and put a layer above that. It is >not a problem to make a program belive i got an virtual drive if it uses file >handles. However if the program uses the old DOS 1.0 file control blocks you >may have some hard work to do. Anyway you must have a tecnical reference over >MS-DOS. This is the "SHELL" approach I described in my article. I want to avoid this approach if possible. Several people (thanks!) have mailed me with information on the redirector interrupt being documented in the standard interrupt list, and that it's on interrupt 2Fh, with AH=11h. The minor function is in AL; unfortunately, with the exception of the standard functions 00/01/FF, there's no hint of which minor functions do what. Sigh. I've been recommended the book "Inside NetBIOS" for further information. I'm currently trying to locate a copy of that book. Thanks for the info, all. If you find out anything I haven't posted, please don't hesitate to send E-Mail. -- Chip Salzenberg <chip@ateng.com> or <uunet!ateng!chip> A T Engineering Me? Speak for my company? Surely you jest! "It's no good. They're tapping the lines."