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From: NETOPRWA@ncsuvm.ncsu.edu (Wayne Aiken)
Newsgroups: alt.bbs,comp.sys.ibm.pc,alt.msdos.programmer
Subject: Re: C/Bulletin Board Live Door/Ctty Problem
Message-ID: <90034.003834NETOPRWA@NCSUVM.BITNET>
Date: 3 Feb 90 05:38:33 GMT
Organization: North Carolina State University Computing Center
Lines: 36

In article <8200@bunny.GTE.COM> hhg1@GTE.COM (Hallett German) asks:
>The sysop  of NESUG BBS is trying to build a live door and has run into
>this problem. He is using Microsoft C and wants to know how to redirect
>without using CTTY. Your help is appreciated. Here is his note below:
>
>I would like to know the standard for writing a applications C program
>which uses either the local screen or com1: for output automatically.
>
>Currently, I am using CTTY COM1: prior to execution and CTTY CON: after
>execution of C program.  Howvever, for security reasons this is not
>recommended.  Also this does not allow for the flexibility to run one
>application program which will take care of both situations depending
>on whether com1: is active.

First: make sure the program traps Ctrl-C and other nasty characters which
could abort the program, giving the remote user access to DOS.

For the COM: port, I recommend using a device driver such as GATEWAY.  When
you do a CTTY to GATEx, all output (from stdout) is written both to the local
screen and to the COM: port.  Plus, both the local keyboard and the remote
user can enter characters to the program.  Then, do a CTTY CON: when the
program is finished.  Thus, the program doesn't have to know anything at all
about the COM: port (except possibly monitoring Carrier Detect...)

It's tough to write a program to monitor both local and/or remotes; and
although this method still uses CTTY, the GATEWAY package seems relatively
well-behaved and secure.  If you still don't want CTTY, try doing a
fprintf() with the device name instead of a file/stream pointer.

This is available on SIMTEL20, or my BBS  (919) 782-3095.  I have no interest
in GATEWAY other than a satisfied user.

Wayne Aiken                netoprwa@ncsuvm.bitnet      "You can BE what
PO Box 30904               netoprwa@ncsuvm.ncsu.edu     you WON'T!!"
Raleigh, NC  27622         wayne@shumv1.ncsu.edu         --"Bob"
(919) 782-8171             BBS: (919) 782-3095