🚀 go-pugleaf

In article <162@lamont.UUCP>, rbd@lamont.UUCP (Roger Davis) writes:
> 
>        ii) Attempting to rlogin from the PDP to a Sun
> 	   crashes the PDP about 75% of the time with a
> 	   "panic: dtom" message, and
> 	   succeeds the other 25% of the time.

There is a simple fix to sohasoutofband() in sys/socket.c that will
prevent one kind of dtom panic:

	sohasoutofband(so)
		struct socket *so;
	{
		mapinfo map;

wrong!		savemap(map);
		if (so->so_pgrp == 0)
			return;
right!		savemap(map);

Remove the savemap(map) call before the if/return and place it after them.
That removes the possibility of an unbalanced savemap/restoremap pair.

Vic Abell, abe@j.cc.purdue.edu
	   j.cc.purdue.edu!abe

>These facts, together with Sun's admission that there were major
>alterations made to rlogin and in.rlogind between 3.0 and 3.2 (mostly
>to pass along window size information),

"Admission" is hardly the appropriate word here.  The major
alterations were made by Berkeley for 4.3BSD; we picked them up for
3.2 because they are a major win, especially when doing "rlogin"s
from a Sun where windows are quite often *not* the canonical 34x80
Sun window and often change size during a session.

>Is this due to a lack of robustness in the 2.9 networking (possible
>bug fix in 2.10?) or is Sun doing something to rlogin that is
>incompatible with 2.9 and maybe other systems as well?

The people at Berkeley's CSRG were the ones who did something to
"rlogin", not us.  The only differences between our "rlogin" and the
4.3BSD one are that ours supports the Sun-style "ioctl" to get the
window size and that ours actually checks the return code from
various network and pseudo-tty I/O operations.  The only differences
between our "in.rlogind" and the 4.3BSD "rlogind" are that ours
supports the Sun-style "ioctl" and has otherwise been modified to run
under a system closer to 4.2BSD than to 4.3BSD, and that it uses a
different strategy for dealing with "write"s that return EWOULDBLOCK.

My suspicion is that 2.9 is at fault here (sorry, Keith).  The fact
that the 2.9 machine crashes indicates that there is certainly at
least one 2.9BSD bug - no machine should crash just because some
packet it doesn't understand comes over the wire.

If you try to log in to a system running the 4.3BSD "rlogin" daemon,
such as a Sun running SunOS 3.2, the "rlogind" daemon will send an
out-of-band message telling the "rlogin" client that it's a new-style
daemon and that it should send the daemon updates when the window
size changes.  The chances are that the 2.9BSD code is somehow not
handling this properly.