Date: Mon, 19 Feb 96 22:09 WET From: uhclem@nemesis.lonestar.org To: FreeBSD-gnats-submit@freebsd.org Subject: bin/1037: 2.x telnetd handles CTRL-M differently than other ttys FDIV044 Message-ID: <m0tojOB-000CiCC@nemesis.lonestar.org> Resent-Message-ID: <199602200420.UAA18436@freefall.freebsd.org>
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>Number: 1037
>Category: bin
>Synopsis: 2.x telnetd handles CTRL-M differently than other ttys FDIV044
>Confidential: no
>Severity: non-critical
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Mon Feb 19 20:20:01 PST 1996
>Last-Modified:
>Originator: Frank Durda IV
>Organization:
That's extra
>Release: FreeBSD 2.1-STABLE i386
>Environment:
FreeBSD 2.1.0 stock system, using various applications that place
tty in character-at-a-time modes.
>Description:
Some applications that ran correctly under BSD43 on vaxen, and later on
SYSIII, SYS5 and 1.1.5.1 PC systems break when used via telnet in 2.0.5
or 2.1.0.
When these programs are running, they interactively parse each character
received, including [ENTER], which is received as 0x0a when the program
is run from the console (syscons), from a terminal attached to a sio port,
or when connected using via telnet using telnetd from 1.1.5.1.
When the telnetd from 2.0.5 or 2.1.0 is used, instead of a 0x0a,
the program receives a 0x0d character, which it does not expect (never
sees anywhere else) and treats as an not-valid-here character.
>How-To-Repeat:
The attached code fragment can be compiled to demonstrate the problem.
Simply run it from terminals, the console, and from telnet sessions to
see the difference in performance. (I have stripped out the SYS3-specific
code, but can provide it if needed.) Follow the instructions in the
program source.
-----enterbug.c-----
/* This program is peeled out of a much larger program called
xmail. When run in 2.1.0 over telnet, pressing ENTER
is no longer detected by the program as receiving a 0x0a
as it did in 1.1.5.1 telnet sessions, or from ttys, or
from the console, or on other platforms (BSD43, SYS3, SYSV)
that this program has been used on.
Start the program, and press at least the following keys:
[ENTER] [CTRL][J] [CTRL][M] Press Capital Q to exit.
Here is what I see here: (This is a 2.1.0 system)
System sio telnetd telnetd
console tty 2.1.0 1.1.5.1*
[ENTER] 0a 0a **0d** 0a
[CTRL][J] 0a 0a 0a 0a
[CTRL][M] 0a 0a **0d** 0a
* By replacing the 2.1.0 telnetd with the telnetd from 1.1.5.1
(but still running on a 2.1.0 system), the correct character
(0x0a) is returned when ENTER is presed.
Run this program from the console, from terminals, and then
via telnet to see the difference in behavior.
*/
#include <stdio.h>
#include <sgtty.h>
#include <sys/stat.h>
#include <sys/file.h>
#define TRUE 1
#define FALSE 0
#define EOT '\004'
static struct sgttyb old, new;
static struct stat ttystatus;
static int eof=EOT, killc=CTRL('U'), erase=CTRL('H'), werase=CTRL('W');
char *ttynam_stdout;
int stdin_isatty, stdout_isatty;
main()
{
char c;
save_tty();
set_tty();
clearerr(stdin);
do {
c = getchar();
printf("%02x ",c);
} while (c != 'Q');
restore_tty();
exit(0);
}
save_tty()
{
struct tchars tc;
fstat(fileno(stdout), &ttystatus);
ttynam_stdout = (char*) ttyname(fileno(stdout));
stdout_isatty = (ioctl(fileno(stdout), TIOCGETP, &old) >= 0);
stdin_isatty = (ioctl(fileno(stdin), TIOCGETP, &old) >= 0);
printf("stdin is%s a tty\n",stdin_isatty?"":" not");
printf("stdout is%s a tty\n",stdout_isatty?"":" not");
killc = (int)old.sg_kill;
erase = (int)old.sg_erase;
if (ioctl(fileno(stdin), TIOCGETC, &tc) == 0)
eof = (int)tc.t_eofc;
new = old;
new.sg_flags |= CBREAK;
new.sg_flags &= ~ECHO;
}
set_tty()
{
ioctl(fileno(stdin), TIOCSETN, &new);
}
restore_tty()
{
if (stdout_isatty)
chmod(ttynam_stdout, (int)ttystatus.st_mode&0777);
if (stdin_isatty)
ioctl(fileno(stdin), TIOCSETP, &old);
}
-----end of enterbug.c-----
>Fix:
The workaround is to replace the telnetd in 2.1.0 or 2.0.5
with the telnetd from 1.1.5.1. This solves this problem and allows
these legacy applications to be used on FreeBSD 2.x.
*END*
>Audit-Trail:
>Unformatted:
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