4.2 telnet and XON/XOFF flow control

[Liudvikas Bukys]

Index:	ucb/telnet.c 4.2 Fix

Description:
	Some terminals require local XON/XOFF flow control to work
	right, e.g., VT125s at >2400 baud, or just about anything at
	19.2Kbaud without hardware flow control.

	Telnet should leave this enabled, at least as an option.

Repeat-By:
	Find such a terminal, telnet to something, and watch your
	terminal lose characters when the remote system doesn't
	respond quickly enough.

Fix:
	The following diffs add a "flow" command for toggling the
	presence of flow control.  It defaults to "on", but the default
	can be changed by changing the 1 in line 43 to a 0.

	It really should be an argument line flag, but at least this
	implementation is consistent with the rest of the telnet option
	setting code.

Diffs (-c):
-------

*** /tmp/,RCSt1026121	(old)
--- telnet.c		(new)
***************
*** 40,45
  int	options;
  int	debug = 0;
  int	crmod = 0;
  char	*prompt;
  char	escape = CTRL(]);
  

--- 40,46 -----
  int	options;
  int	debug = 0;
  int	crmod = 0;
+ int	flow = 1;
  char	*prompt;
  char	escape = CTRL(]);
  
***************
*** 54,60
  
  int	tn(), quit(), suspend(), bye(), help();
  int	setescape(), status(), toggle(), setoptions();
! int	setcrmod(), setdebug();
  
  #define HELPINDENT (sizeof ("connect"))
  

--- 55,61 -----
  
  int	tn(), quit(), suspend(), bye(), help();
  int	setescape(), status(), toggle(), setoptions();
! int	setcrmod(), setflow(), setdebug();
  
  #define HELPINDENT (sizeof ("connect"))
  
***************
*** 74,79
  char	helphelp[] =	"print help information";
  char	optionshelp[] =	"toggle viewing of options processing";
  char	crmodhelp[] =	"toggle mapping of received carriage returns";
  
  struct cmd cmdtab[] = {
  	{ "open",	openhelp,	tn },

--- 75,81 -----
  char	helphelp[] =	"print help information";
  char	optionshelp[] =	"toggle viewing of options processing";
  char	crmodhelp[] =	"toggle mapping of received carriage returns";
+ char	flowhelp[] =	"toggle flow control (usually XON/XOFF)";
  
  struct cmd cmdtab[] = {
  	{ "open",	openhelp,	tn },
***************
*** 84,89
  	{ "status",	statushelp,	status },
  	{ "options",	optionshelp,	setoptions },
  	{ "crmod",	crmodhelp,	setcrmod },
  	{ "debug",	debughelp,	setdebug },
  	{ "?",		helphelp,	help },
  	0

--- 86,92 -----
  	{ "status",	statushelp,	status },
  	{ "options",	optionshelp,	setoptions },
  	{ "crmod",	crmodhelp,	setcrmod },
+ 	{ "flow",	flowhelp,	setflow },
  	{ "debug",	debughelp,	setdebug },
  	{ "?",		helphelp,	help },
  	0
***************
*** 354,359
  		tc = ¬c;
  		ltc = &noltc;
  		onoff = 1;
  		break;
  
  	default:

--- 357,367 -----
  		tc = ¬c;
  		ltc = &noltc;
  		onoff = 1;
+ 		if (flow) {
+ 			notc.t_startc = otc.t_startc;
+ 			notc.t_stopc = otc.t_stopc;
+ 		} else
+ 			notc.t_startc = notc.t_stopc = -1;
  		break;
  
  	default:
***************
*** 721,726
  
  	crmod = !crmod;
  	printf("%s map carriage return on output.\n", crmod ? "Will" : "Wont");
  	fflush(stdout);
  }
  

--- 729,747 -----
  
  	crmod = !crmod;
  	printf("%s map carriage return on output.\n", crmod ? "Will" : "Wont");
+ 	fflush(stdout);
+ }
+ 
+ /*VARARGS*/
+ setflow()
+ {
+ 
+ 	flow = !flow;
+ 	printf("%s use local flow control.\n", flow ? "Will" : "Wont");
+ 	if (flow) {
+ 		printf("(%s to stop,", control(otc.t_stopc));
+ 		printf(" %s to start)\n", control(otc.t_startc));
+ 	}
  	fflush(stdout);
  }

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