Date: Tue, 10 Sep 1996 20:30:38 -0500 (CDT) From: David Kelly <dkelly@hiwaay.net> To: hackers@freebsd.org Cc: Jim Durham <durham@w2xo.pgh.pa.us>, John Perry <perry@alpha.jpunix.com> Subject: pty's and slattach Message-ID: <XFMail.960910211424.dkelly@hiwaay.net>
next in thread | raw e-mail | index | archive | help
In the amateur radio world where Linux dominates amateur radio operators
have their (our) own suite of network protocols, namely AX.25. Linux
developers have built AX.25 support into Linux kernels, yet there are
many Linux users that don't use that mode for one reason or another.
One of many derivatives of Phil Karn KA9Q's NET/NOS is usually run in DOS
to produce an advanced network node. There are two (that I know of)
derivatives for Un*x, WAMPES (out of Germany?) and TNOS (out of Tampa, FL)
that continue the DOS tradition under Un*x... until something better comes
along.
Ok, so far we've got a single large do-everything binary that implements a
BBS, telnet, ftp, nntp, smtp, slip, ppp, etc, over AX.25. But no connection
back to the Un*x kernel. Whats currently used in Linux is a SL/IP connection
thru a pty/tty pair. In TNOS an attach line to the kernal migh look like
this if connecting to a host named "bsd":
attach asy ttypf - slip bsd 2048 1024 38400
And you'd like to catch that slip connection (on the FreeBSD side) with:
slattach -l -L /dev/ptypf
or similar. Of course you should realize by now it works somewhere else but
not in FreeBSD. What we get in /var/log/messages is:
Sep 10 19:53:08 nexgen slattach[11472]: ioctl(TIOCSCTTY): Operation
not permitted
No telling what will break next when we get that fixed. :-)
Studying /usr/src/sys/kern/tty_pty.c I find no mention of TIOCSCTTY. No
wonder its not permitted. Studying /usr1/src/sbin/slattach/slattach.c we
find:
/* acquire the serial line as a controling terminal. */
if (ioctl(fd, TIOCSCTTY, 0) < 0) {
syslog(LOG_ERR,"ioctl(TIOCSCTTY): %m");
exit_handler(1);
}
I don't know how to run gdb thru a daemon(0,0), but I'm quite sure this is
where the error message originates and slattach quits. A bandaid approach
would be to bypass the above in slattach. But I don't know enough about
*why* the author of slattach.c wants to be a controlling terminal to be
confident about skipping the ioctl(). And I don't know enough about the
operation of the pty driver to be able to add support for TIOCSCTTY or
answer the question, "why isn't it in there already?"
Am going to start digging thru my texts and see what I can learn about
terminal I/O. Gotta figure out what a "controlling terminal" is. And this
other stuff about "process groups".
Obviously lots of stuff works very well thru pty's. The most correct fix
would be to take the amateur radio code and teach it to connect to the tun
device directly. Or the sl devices. But for now I'd like to get this other
stuff working thru pty.
Oh, and before I forget to mention I'm running something between 2.1.0R and
2.1.5R.... if it makes any difference. Should I grab -current?
Any suggestions?
--
David Kelly N4HHE, dkelly@tomcat1.tbe.com (wk), dkelly@hiwaay.net (hm)
=====================================================================
The human mind ordinarily operates at only ten percent of its
capacity -- the rest is overhead for the operating system.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?XFMail.960910211424.dkelly>