[14124] in Athena Bugs
telnetd: spurious "You must use the encryption option"
daemon@ATHENA.MIT.EDU (brlewis@MIT.EDU)
Thu Jan 18 10:34:44 1996
From: brlewis@MIT.EDU
Date: Thu, 18 Jan 96 10:34:38 -0500
To: bugs@MIT.EDU
Sometimes users of NCSA telnet for Mac find that their windows disappear
mysteriously. Setting an option that makes the window stay up shows
that there's a "You must use the encryption option" message even though
they have the encryption option turned on. What happens is that telnetd
gets to the password prompt before NCSA telnet starts encryption.
The following patches to telnetd make it wait for a slow client to go
ahead and start encryption if encryption is required.
*** 1.1 1995/04/26 19:25:51
--- state.c 1995/04/27 00:50:31
***************
*** 1480,1485 ****
--- 1480,1486 ----
break;
case ENCRYPT_START:
encrypt_start(subpointer, SB_LEN());
+ did_encrypt_start = 1;
break;
case ENCRYPT_END:
encrypt_end();
*** 1.4 1995/03/16 20:04:03
--- telnetd.c 1995/04/27 00:18:15
***************
*** 79,84 ****
--- 79,88 ----
int require_SecurID = 0;
#endif
+ #if defined(ENCRYPTION)
+ int did_encrypt_start = 0;
+ #endif
+
extern int utmp_len;
int registered_host_only = 0;
***************
*** 126,131 ****
--- 130,139 ----
int lowpty = 0, highpty; /* low, high pty numbers */
#endif /* CRAY */
+ #ifdef ATHENA_LOGIN
+ #include <unistd.h> /* for POSIX alarm() */
+ #endif
+
int debug = 0;
int keepalive = 1;
char *progname;
***************
*** 590,595 ****
--- 598,614 ----
IAC, SB, TELOPT_TTYPE, TELQUAL_SEND, IAC, SE
};
+
+ #ifdef ATHENA_LOGIN
+ int alarm_caught;
+ void
+ alarm_catcher(int sig)
+ {
+ if (sig == SIGALRM) alarm_caught++;
+ return;
+ }
+ #endif
+
int
getterminaltype(name)
char *name;
***************
*** 622,627 ****
--- 641,647 ----
while (
#ifdef ENCRYPTION
his_do_dont_is_changing(TELOPT_ENCRYPT) ||
+ his_will_wont_is_changing(TELOPT_ENCRYPT) ||
#endif /* ENCRYPTION */
his_will_wont_is_changing(TELOPT_TTYPE) ||
his_will_wont_is_changing(TELOPT_TSPEED) ||
***************
*** 637,642 ****
--- 657,686 ----
*/
if (his_state_is_will(TELOPT_ENCRYPT)) {
encrypt_wait();
+ #ifdef ATHENA_LOGIN
+ if (auth_level < 0) /* asking for password regardless of krb auth */
+ {
+ struct sigaction alarm_action, old_action;
+
+ alarm_action.sa_handler=alarm_catcher;
+ sigemptyset(&alarm_action.sa_mask);
+ alarm_action.sa_flags=0;
+ sigaction(SIGALRM, &alarm_action, &old_action);
+ /*
+ * Wait for encryption to actually start.
+ */
+ alarm_caught=0;
+ while (!did_encrypt_start)
+ {
+ alarm(5); /* wait 5 seconds for more input */
+ ttloop(); /* hopefully receive ENCRYPT REQUEST-START */
+ if (alarm_caught) break; /* give up */
+ }
+ alarm(0);
+ sigaction(SIGALRM, &old_action, NULL);
+ }
+
+ #endif /* ATHENA_LOGIN */
}
#endif /* ENCRYPTION */
if (his_state_is_will(TELOPT_TSPEED)) {
*** 1.3 1995/02/02 16:09:52
--- utility.c 1995/04/27 00:14:02
***************
*** 36,41 ****
--- 36,42 ----
#endif /* not lint */
#define PRINTOPTIONS
+ #include <errno.h>
#include "telnetd.h"
/*
***************
*** 63,68 ****
--- 64,70 ----
}
ncc = read(net, netibuf, sizeof netibuf);
if (ncc < 0) {
+ if (errno == EINTR) return; /* interrupt from alarm() */
syslog(LOG_INFO, "ttloop: read: %m\n");
exit(1);
} else if (ncc == 0) {
*** 1.1 1995/04/26 19:21:50
--- ext.h 1995/04/27 00:51:20
***************
*** 63,68 ****
--- 63,71 ----
#if defined(AUTHENTICATION)
extern int auth_level;
#endif
+ #if defined(ENCRYPTION)
+ extern int did_encrypt_start;
+ #endif
extern slcfun slctab[NSLC + 1]; /* slc mapping table */
