steve@gec-mi-at.co.uk (Steve Lademann) (07/08/87)
Having spent the last couple of months upgrading two 11/750s to 4.3BSD, I
have encountered a few minor bugs which I have fixes for. This one is in
telnet.
Problem: We have a lot of System V.0 systems, and a few other
miscellaneous systems using vintage telnets which will
not interwork with the 4.3BSD telnet daemon. This is
due to the new features added to 4.3BSD which arbitrate
terminal types, etc. When used with a very old telnet, the
daemon hangs waiting for a response from the remote telnet.
Fix: This modification adds a timeout around the code which waits
for a response.
*** telnetd.c.old Tue May 13 06:21:51 1986
--- telnetd.c Wed Jul 8 12:50:36 1987
***************
*** 17,22 ****
--- 17,28 ----
/*
* Telnet server.
*/
+
+ /*
+ * Modified by steve@gec-mi-at.co.uk to enable Sytem V.0 telnets to work
+ * with BSD4.3
+ */
+
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/wait.h>
***************
*** 64,69 ****
--- 70,76 ----
char *neturg = 0; /* one past last bye of urgent data */
/* the remote system seems to NOT be an old 4.2 */
int not42 = 1;
+ int sysV0 = 0; /* Flag to identify a stone-age telnet client */
char BANNER1[] = "\r\n\r\n4.3 BSD UNIX (",
***************
*** 209,226 ****
--- 216,247 ----
* Output is the variable terminaltype filled in.
*/
+ #include <setjmp.h>
+ jmp_buf tmo;
+
void
getterminaltype()
{
static char sbuf[] = { IAC, DO, TELOPT_TTYPE };
+ int tmout();
settimer(getterminal);
bcopy(sbuf, nfrontp, sizeof sbuf);
nfrontp += sizeof sbuf;
hisopts[TELOPT_TTYPE] = OPT_YES_BUT_ALWAYS_LOOK;
+ if (setjmp(tmo))
+ {
+ hisopts[TELOPT_TTYPE] = OPT_NO;
+ sysV0 = 1; /* Kludge ^ 2 It must be a stone-age client */
+ return;
+ }
+ signal(SIGALRM,tmout);
+ alarm(2);
while (sequenceIs(ttypeopt, getterminal)) {
ttloop();
}
+ signal(SIGALRM,SIG_DFL);
+ alarm(0);
if (hisopts[TELOPT_TTYPE] == OPT_YES) {
static char sbbuf[] = { IAC, SB, TELOPT_TTYPE, TELQUAL_SEND, IAC, SE };
***************
*** 232,237 ****
--- 253,263 ----
}
}
+ int tmout()
+ {
+ longjmp(tmo,1);
+ }
+
/*
* Get a pty, scan input lines.
*/
***************
*** 408,417 ****
* WE, the server, sends it; it does NOT mean that the client will
* echo the terminal input).
*/
! sprintf(nfrontp, doopt, TELOPT_ECHO);
! nfrontp += sizeof doopt-2;
! hisopts[TELOPT_ECHO] = OPT_YES_BUT_ALWAYS_LOOK;
/*
* Show banner that getty never gave.
*
--- 434,452 ----
* WE, the server, sends it; it does NOT mean that the client will
* echo the terminal input).
*/
! /*
! * However, the following code does not help System V.0 systems,
! * which we identify by there reluctance to reply to the terminal
! * type sequence (KLUDGE UPON KLUDGE)! steve@gec-mi-at.co.uk
! */
+ if (!sysV0)
+ {
+ sprintf(nfrontp, doopt, TELOPT_ECHO);
+ nfrontp += sizeof doopt-2;
+ hisopts[TELOPT_ECHO] = OPT_YES_BUT_ALWAYS_LOOK;
+ }
+
/*
* Show banner that getty never gave.
*
|Steve Lademann |Phone: 44 727 59292 x326 |
|Marconi Instruments Ltd|UUCP : ...mcvax!ukc!hrc63!miduet!steve |
|St. Albans AL4 0JN |NRS : steve@uk.co.gec-mi-at |
|Herts. UK | "disclaimers.all"