Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!rick
From: rick@seismo.CSS.GOV (Rick Adams)
Newsgroups: net.bugs.4bsd
Subject: 4.3 BSD telnet can get into infinite loop
Message-ID: <41296@beno.seismo.CSS.GOV>
Date: Fri, 15-Aug-86 16:40:16 EDT
Article-I.D.: beno.41296
Posted: Fri Aug 15 16:40:16 1986
Date-Received: Sun, 17-Aug-86 06:13:02 EDT
Sender: news@seismo.CSS.GOV
Organization: Center for Seismic Studies, Arlington, VA
Lines: 114
Keywords: telnet eof


Subject: telnet can infinite loop if eof on input
Index:	ucb/telnet.c 4.3BSD

Description:
	1) telnet should exit non-zero if connect failed
		this is useful for shell scripts if you want to test if
		a host is up
	2) telnet can go into an infinite loop if stdin returns EOF
Repeat-By:
	1) grep exit() telnet.c
	2) telnet localhosts </dev/null
Fix:
*** telnet.c.old	Fri Aug 15 16:03:39 1986
--- telnet.c		Fri Aug 15 15:57:15 1986
***************
*** 98,104 ****
  	int	needconnect;	/* Do we need to be connected to execute? */
  };
  
! int	connected;
  int	net;
  int	tout;
  int	showoptions = 0;
--- 98,104 ----
  	int	needconnect;	/* Do we need to be connected to execute? */
  };
  
! int	connected, didconnect;
  int	net;
  int	tout;
  int	showoptions = 0;
***************
*** 731,737 ****
  
  char	sibuf[BUFSIZ], *sbp;
  char	tibuf[BUFSIZ], *tbp;
! int	scc, tcc;
  
  
  /*
--- 731,737 ----
  
  char	sibuf[BUFSIZ], *sbp;
  char	tibuf[BUFSIZ], *tbp;
! int	scc, tcc, neofs;
  
  
  /*
***************
*** 903,909 ****
  					/* must be an EOF... */
  					*tbp = ntc.t_eofc;
  					c = 1;
! 				}
  				if (c <= 0) {
  					tcc = c;
  					break;
--- 903,913 ----
  					/* must be an EOF... */
  					*tbp = ntc.t_eofc;
  					c = 1;
! 					if (neofs++ > 4)
! 						quit();
! 				} else
! 					neofs = 0;
! 
  				if (c <= 0) {
  					tcc = c;
  					break;
***************
*** 1980,1986 ****
  quit()
  {
  	(void) call(bye, "bye", 0);
! 	exit(0);
  	/*NOTREACHED*/
  }
  
--- 1984,1990 ----
  quit()
  {
  	(void) call(bye, "bye", 0);
! 	exit(didconnect ? 0 : 1);
  	/*NOTREACHED*/
  }
  
***************
*** 2115,2120 ****
--- 2119,2125 ----
  			return 0;
  		}
  		connected++;
+ 		didconnect++;
  	} while (connected == 0);
  	call(status, "status", "notmuch", 0);
  	if (setjmp(peerdied) == 0)
***************
*** 2355,2361 ****
  	}
  	if (argc != 1) {
  		if (setjmp(toplevel) != 0)
! 			exit(0);
  		tn(argc, argv);
  	}
  	setjmp(toplevel);
--- 2360,2366 ----
  	}
  	if (argc != 1) {
  		if (setjmp(toplevel) != 0)
! 			exit(didconnect ? 0 : 1);
  		tn(argc, argv);
  	}
  	setjmp(toplevel);