xref: /haiku/src/bin/network/telnetd/state.c (revision 13581b3d2a71545960b98fefebc5225b5bf29072)
1 /*
2  * Copyright (c) 1989, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. Neither the name of the University nor the names of its contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  */
29 
30 #if 0
31 #ifndef lint
32 static const char sccsid[] = "@(#)state.c	8.5 (Berkeley) 5/30/95";
33 #endif
34 #endif
35 #include <sys/cdefs.h>
36 __FBSDID("$FreeBSD$");
37 
38 #include <stdarg.h>
39 #include "telnetd.h"
40 #ifdef	AUTHENTICATION
41 #include <libtelnet/auth.h>
42 #endif
43 #ifdef	ENCRYPTION
44 #include <libtelnet/encrypt.h>
45 #endif
46 
47 unsigned char	doopt[] = { IAC, DO, '%', 'c', 0 };
48 unsigned char	dont[] = { IAC, DONT, '%', 'c', 0 };
49 unsigned char	will[] = { IAC, WILL, '%', 'c', 0 };
50 unsigned char	wont[] = { IAC, WONT, '%', 'c', 0 };
51 int	not42 = 1;
52 
53 /*
54  * Buffer for sub-options, and macros
55  * for suboptions buffer manipulations
56  */
57 unsigned char subbuffer[512], *subpointer= subbuffer, *subend= subbuffer;
58 
59 #define	SB_CLEAR()	subpointer = subbuffer
60 #define	SB_TERM()	{ subend = subpointer; SB_CLEAR(); }
61 #define	SB_ACCUM(c)	if (subpointer < (subbuffer+sizeof subbuffer)) { \
62 				*subpointer++ = (c); \
63 			}
64 #define	SB_GET()	((*subpointer++)&0xff)
65 #define	SB_EOF()	(subpointer >= subend)
66 #define	SB_LEN()	(subend - subpointer)
67 
68 #ifdef	ENV_HACK
69 unsigned char *subsave;
70 #define SB_SAVE()	subsave = subpointer;
71 #define	SB_RESTORE()	subpointer = subsave;
72 #endif
73 
74 
75 /*
76  * State for recv fsm
77  */
78 #define	TS_DATA		0	/* base state */
79 #define	TS_IAC		1	/* look for double IAC's */
80 #define	TS_CR		2	/* CR-LF ->'s CR */
81 #define	TS_SB		3	/* throw away begin's... */
82 #define	TS_SE		4	/* ...end's (suboption negotiation) */
83 #define	TS_WILL		5	/* will option negotiation */
84 #define	TS_WONT		6	/* wont " */
85 #define	TS_DO		7	/* do " */
86 #define	TS_DONT		8	/* dont " */
87 
88 static void doclientstat(void);
89 
90 void
91 telrcv(void)
92 {
93 	int c;
94 	static int state = TS_DATA;
95 
96 	while (ncc > 0) {
97 		if ((&ptyobuf[BUFSIZ] - pfrontp) < 2)
98 			break;
99 		c = *netip++ & 0377, ncc--;
100 #ifdef	ENCRYPTION
101 		if (decrypt_input)
102 			c = (*decrypt_input)(c);
103 #endif	/* ENCRYPTION */
104 		switch (state) {
105 
106 		case TS_CR:
107 			state = TS_DATA;
108 			/* Strip off \n or \0 after a \r */
109 			if ((c == 0) || (c == '\n')) {
110 				break;
111 			}
112 			/* FALLTHROUGH */
113 
114 		case TS_DATA:
115 			if (c == IAC) {
116 				state = TS_IAC;
117 				break;
118 			}
119 			/*
120 			 * We now map \r\n ==> \r for pragmatic reasons.
121 			 * Many client implementations send \r\n when
122 			 * the user hits the CarriageReturn key.
123 			 *
124 			 * We USED to map \r\n ==> \n, since \r\n says
125 			 * that we want to be in column 1 of the next
126 			 * printable line, and \n is the standard
127 			 * unix way of saying that (\r is only good
128 			 * if CRMOD is set, which it normally is).
129 			 */
130 			if ((c == '\r') && his_state_is_wont(TELOPT_BINARY)) {
131 				int nc = *netip;
132 #ifdef	ENCRYPTION
133 				if (decrypt_input)
134 					nc = (*decrypt_input)(nc & 0xff);
135 #endif	/* ENCRYPTION */
136 #ifdef	LINEMODE
137 				/*
138 				 * If we are operating in linemode,
139 				 * convert to local end-of-line.
140 				 */
141 				if (linemode && (ncc > 0) && (('\n' == nc) ||
142 					 ((0 == nc) && tty_iscrnl())) ) {
143 					netip++; ncc--;
144 					c = '\n';
145 				} else
146 #endif
147 				{
148 #ifdef	ENCRYPTION
149 					if (decrypt_input)
150 						(void)(*decrypt_input)(-1);
151 #endif	/* ENCRYPTION */
152 					state = TS_CR;
153 				}
154 			}
155 			*pfrontp++ = c;
156 			break;
157 
158 		case TS_IAC:
159 gotiac:			switch (c) {
160 
161 			/*
162 			 * Send the process on the pty side an
163 			 * interrupt.  Do this with a NULL or
164 			 * interrupt char; depending on the tty mode.
165 			 */
166 			case IP:
167 				DIAG(TD_OPTIONS,
168 					printoption("td: recv IAC", c));
169 				interrupt();
170 				break;
171 
172 			case BREAK:
173 				DIAG(TD_OPTIONS,
174 					printoption("td: recv IAC", c));
175 				sendbrk();
176 				break;
177 
178 			/*
179 			 * Are You There?
180 			 */
181 			case AYT:
182 				DIAG(TD_OPTIONS,
183 					printoption("td: recv IAC", c));
184 				recv_ayt();
185 				break;
186 
187 			/*
188 			 * Abort Output
189 			 */
190 			case AO:
191 			    {
192 				DIAG(TD_OPTIONS,
193 					printoption("td: recv IAC", c));
194 				ptyflush();	/* half-hearted */
195 				init_termbuf();
196 
197 				if (slctab[SLC_AO].sptr &&
198 				    *slctab[SLC_AO].sptr != (cc_t)(_POSIX_VDISABLE)) {
199 				    *pfrontp++ =
200 					(unsigned char)*slctab[SLC_AO].sptr;
201 				}
202 
203 				netclear();	/* clear buffer back */
204 				output_data("%c%c", IAC, DM);
205 				neturg = nfrontp-1; /* off by one XXX */
206 				DIAG(TD_OPTIONS,
207 					printoption("td: send IAC", DM));
208 				break;
209 			    }
210 
211 			/*
212 			 * Erase Character and
213 			 * Erase Line
214 			 */
215 			case EC:
216 			case EL:
217 			    {
218 				cc_t ch;
219 
220 				DIAG(TD_OPTIONS,
221 					printoption("td: recv IAC", c));
222 				ptyflush();	/* half-hearted */
223 				init_termbuf();
224 				if (c == EC)
225 					ch = *slctab[SLC_EC].sptr;
226 				else
227 					ch = *slctab[SLC_EL].sptr;
228 				if (ch != (cc_t)(_POSIX_VDISABLE))
229 					*pfrontp++ = (unsigned char)ch;
230 				break;
231 			    }
232 
233 			/*
234 			 * Check for urgent data...
235 			 */
236 			case DM:
237 				DIAG(TD_OPTIONS,
238 					printoption("td: recv IAC", c));
239 				SYNCHing = stilloob(net);
240 				settimer(gotDM);
241 				break;
242 
243 
244 			/*
245 			 * Begin option subnegotiation...
246 			 */
247 			case SB:
248 				state = TS_SB;
249 				SB_CLEAR();
250 				continue;
251 
252 			case WILL:
253 				state = TS_WILL;
254 				continue;
255 
256 			case WONT:
257 				state = TS_WONT;
258 				continue;
259 
260 			case DO:
261 				state = TS_DO;
262 				continue;
263 
264 			case DONT:
265 				state = TS_DONT;
266 				continue;
267 			case EOR:
268 				if (his_state_is_will(TELOPT_EOR))
269 					doeof();
270 				break;
271 
272 			/*
273 			 * Handle RFC 10xx Telnet linemode option additions
274 			 * to command stream (EOF, SUSP, ABORT).
275 			 */
276 			case xEOF:
277 				doeof();
278 				break;
279 
280 			case SUSP:
281 				sendsusp();
282 				break;
283 
284 			case ABORT:
285 				sendbrk();
286 				break;
287 
288 			case IAC:
289 				*pfrontp++ = c;
290 				break;
291 			}
292 			state = TS_DATA;
293 			break;
294 
295 		case TS_SB:
296 			if (c == IAC) {
297 				state = TS_SE;
298 			} else {
299 				SB_ACCUM(c);
300 			}
301 			break;
302 
303 		case TS_SE:
304 			if (c != SE) {
305 				if (c != IAC) {
306 					/*
307 					 * bad form of suboption negotiation.
308 					 * handle it in such a way as to avoid
309 					 * damage to local state.  Parse
310 					 * suboption buffer found so far,
311 					 * then treat remaining stream as
312 					 * another command sequence.
313 					 */
314 
315 					/* for DIAGNOSTICS */
316 					SB_ACCUM(IAC);
317 					SB_ACCUM(c);
318 					subpointer -= 2;
319 
320 					SB_TERM();
321 					suboption();
322 					state = TS_IAC;
323 					goto gotiac;
324 				}
325 				SB_ACCUM(c);
326 				state = TS_SB;
327 			} else {
328 				/* for DIAGNOSTICS */
329 				SB_ACCUM(IAC);
330 				SB_ACCUM(SE);
331 				subpointer -= 2;
332 
333 				SB_TERM();
334 				suboption();	/* handle sub-option */
335 				state = TS_DATA;
336 			}
337 			break;
338 
339 		case TS_WILL:
340 			willoption(c);
341 			state = TS_DATA;
342 			continue;
343 
344 		case TS_WONT:
345 			wontoption(c);
346 			state = TS_DATA;
347 			continue;
348 
349 		case TS_DO:
350 			dooption(c);
351 			state = TS_DATA;
352 			continue;
353 
354 		case TS_DONT:
355 			dontoption(c);
356 			state = TS_DATA;
357 			continue;
358 
359 		default:
360 			syslog(LOG_ERR, "panic state=%d", state);
361 			printf("telnetd: panic state=%d\n", state);
362 			exit(1);
363 		}
364 	}
365 }  /* end of telrcv */
366 
367 /*
368  * The will/wont/do/dont state machines are based on Dave Borman's
369  * Telnet option processing state machine.
370  *
371  * These correspond to the following states:
372  *	my_state = the last negotiated state
373  *	want_state = what I want the state to go to
374  *	want_resp = how many requests I have sent
375  * All state defaults are negative, and resp defaults to 0.
376  *
377  * When initiating a request to change state to new_state:
378  *
379  * if ((want_resp == 0 && new_state == my_state) || want_state == new_state) {
380  *	do nothing;
381  * } else {
382  *	want_state = new_state;
383  *	send new_state;
384  *	want_resp++;
385  * }
386  *
387  * When receiving new_state:
388  *
389  * if (want_resp) {
390  *	want_resp--;
391  *	if (want_resp && (new_state == my_state))
392  *		want_resp--;
393  * }
394  * if ((want_resp == 0) && (new_state != want_state)) {
395  *	if (ok_to_switch_to new_state)
396  *		want_state = new_state;
397  *	else
398  *		want_resp++;
399  *	send want_state;
400  * }
401  * my_state = new_state;
402  *
403  * Note that new_state is implied in these functions by the function itself.
404  * will and do imply positive new_state, wont and dont imply negative.
405  *
406  * Finally, there is one catch.  If we send a negative response to a
407  * positive request, my_state will be the positive while want_state will
408  * remain negative.  my_state will revert to negative when the negative
409  * acknowlegment arrives from the peer.  Thus, my_state generally tells
410  * us not only the last negotiated state, but also tells us what the peer
411  * wants to be doing as well.  It is important to understand this difference
412  * as we may wish to be processing data streams based on our desired state
413  * (want_state) or based on what the peer thinks the state is (my_state).
414  *
415  * This all works fine because if the peer sends a positive request, the data
416  * that we receive prior to negative acknowlegment will probably be affected
417  * by the positive state, and we can process it as such (if we can; if we
418  * can't then it really doesn't matter).  If it is that important, then the
419  * peer probably should be buffering until this option state negotiation
420  * is complete.
421  *
422  */
423 void
424 send_do(int option, int init)
425 {
426 	if (init) {
427 		if ((do_dont_resp[option] == 0 && his_state_is_will(option)) ||
428 		    his_want_state_is_will(option))
429 			return;
430 		/*
431 		 * Special case for TELOPT_TM:  We send a DO, but pretend
432 		 * that we sent a DONT, so that we can send more DOs if
433 		 * we want to.
434 		 */
435 		if (option == TELOPT_TM)
436 			set_his_want_state_wont(option);
437 		else
438 			set_his_want_state_will(option);
439 		do_dont_resp[option]++;
440 	}
441 	output_data((const char *)doopt, option);
442 
443 	DIAG(TD_OPTIONS, printoption("td: send do", option));
444 }
445 
446 void
447 willoption(int option)
448 {
449 	int changeok = 0;
450 	void (*func)(void) = 0;
451 
452 	/*
453 	 * process input from peer.
454 	 */
455 
456 	DIAG(TD_OPTIONS, printoption("td: recv will", option));
457 
458 	if (do_dont_resp[option]) {
459 		do_dont_resp[option]--;
460 		if (do_dont_resp[option] && his_state_is_will(option))
461 			do_dont_resp[option]--;
462 	}
463 	if (do_dont_resp[option] == 0) {
464 	    if (his_want_state_is_wont(option)) {
465 		switch (option) {
466 
467 		case TELOPT_BINARY:
468 			init_termbuf();
469 			tty_binaryin(1);
470 			set_termbuf();
471 			changeok++;
472 			break;
473 
474 		case TELOPT_ECHO:
475 			/*
476 			 * See comments below for more info.
477 			 */
478 			not42 = 0;	/* looks like a 4.2 system */
479 			break;
480 
481 		case TELOPT_TM:
482 #if	defined(LINEMODE) && defined(KLUDGELINEMODE)
483 			/*
484 			 * This telnetd implementation does not really
485 			 * support timing marks, it just uses them to
486 			 * support the kludge linemode stuff.  If we
487 			 * receive a will or wont TM in response to our
488 			 * do TM request that may have been sent to
489 			 * determine kludge linemode support, process
490 			 * it, otherwise TM should get a negative
491 			 * response back.
492 			 */
493 			/*
494 			 * Handle the linemode kludge stuff.
495 			 * If we are not currently supporting any
496 			 * linemode at all, then we assume that this
497 			 * is the client telling us to use kludge
498 			 * linemode in response to our query.  Set the
499 			 * linemode type that is to be supported, note
500 			 * that the client wishes to use linemode, and
501 			 * eat the will TM as though it never arrived.
502 			 */
503 			if (lmodetype < KLUDGE_LINEMODE) {
504 				lmodetype = KLUDGE_LINEMODE;
505 				clientstat(TELOPT_LINEMODE, WILL, 0);
506 				send_wont(TELOPT_SGA, 1);
507 			} else if (lmodetype == NO_AUTOKLUDGE) {
508 				lmodetype = KLUDGE_OK;
509 			}
510 #endif	/* defined(LINEMODE) && defined(KLUDGELINEMODE) */
511 			/*
512 			 * We never respond to a WILL TM, and
513 			 * we leave the state WONT.
514 			 */
515 			return;
516 
517 		case TELOPT_LFLOW:
518 			/*
519 			 * If we are going to support flow control
520 			 * option, then don't worry peer that we can't
521 			 * change the flow control characters.
522 			 */
523 			slctab[SLC_XON].defset.flag &= ~SLC_LEVELBITS;
524 			slctab[SLC_XON].defset.flag |= SLC_DEFAULT;
525 			slctab[SLC_XOFF].defset.flag &= ~SLC_LEVELBITS;
526 			slctab[SLC_XOFF].defset.flag |= SLC_DEFAULT;
527 		case TELOPT_TTYPE:
528 		case TELOPT_SGA:
529 		case TELOPT_NAWS:
530 		case TELOPT_TSPEED:
531 		case TELOPT_XDISPLOC:
532 		case TELOPT_NEW_ENVIRON:
533 		case TELOPT_OLD_ENVIRON:
534 			changeok++;
535 			break;
536 
537 #ifdef	LINEMODE
538 		case TELOPT_LINEMODE:
539 # ifdef	KLUDGELINEMODE
540 			/*
541 			 * Note client's desire to use linemode.
542 			 */
543 			lmodetype = REAL_LINEMODE;
544 # endif	/* KLUDGELINEMODE */
545 			func = doclientstat;
546 			changeok++;
547 			break;
548 #endif	/* LINEMODE */
549 
550 #ifdef	AUTHENTICATION
551 		case TELOPT_AUTHENTICATION:
552 			if (auth_level >= 0) {
553 				func = auth_request;
554 				changeok++;
555 			}
556 			break;
557 #endif
558 
559 #ifdef	ENCRYPTION
560 		case TELOPT_ENCRYPT:
561 			func = encrypt_send_support;
562 			changeok++;
563 			break;
564 #endif	/* ENCRYPTION */
565 
566 		default:
567 			break;
568 		}
569 		if (changeok) {
570 			set_his_want_state_will(option);
571 			send_do(option, 0);
572 		} else {
573 			do_dont_resp[option]++;
574 			send_dont(option, 0);
575 		}
576 	    } else {
577 		/*
578 		 * Option processing that should happen when
579 		 * we receive conformation of a change in
580 		 * state that we had requested.
581 		 */
582 		switch (option) {
583 		case TELOPT_ECHO:
584 			not42 = 0;	/* looks like a 4.2 system */
585 			/*
586 			 * Egads, he responded "WILL ECHO".  Turn
587 			 * it off right now!
588 			 */
589 			send_dont(option, 1);
590 			/*
591 			 * "WILL ECHO".  Kludge upon kludge!
592 			 * A 4.2 client is now echoing user input at
593 			 * the tty.  This is probably undesireable and
594 			 * it should be stopped.  The client will
595 			 * respond WONT TM to the DO TM that we send to
596 			 * check for kludge linemode.  When the WONT TM
597 			 * arrives, linemode will be turned off and a
598 			 * change propogated to the pty.  This change
599 			 * will cause us to process the new pty state
600 			 * in localstat(), which will notice that
601 			 * linemode is off and send a WILL ECHO
602 			 * so that we are properly in character mode and
603 			 * all is well.
604 			 */
605 			break;
606 #ifdef	LINEMODE
607 		case TELOPT_LINEMODE:
608 # ifdef	KLUDGELINEMODE
609 			/*
610 			 * Note client's desire to use linemode.
611 			 */
612 			lmodetype = REAL_LINEMODE;
613 # endif	/* KLUDGELINEMODE */
614 			func = doclientstat;
615 			break;
616 #endif	/* LINEMODE */
617 
618 #ifdef	AUTHENTICATION
619 		case TELOPT_AUTHENTICATION:
620 			func = auth_request;
621 			break;
622 #endif
623 
624 #ifdef	ENCRYPTION
625 		case TELOPT_ENCRYPT:
626 			func = encrypt_send_support;
627 			break;
628 #endif	/* ENCRYPTION */
629 		case TELOPT_LFLOW:
630 			func = flowstat;
631 			break;
632 		}
633 	    }
634 	}
635 	set_his_state_will(option);
636 	if (func)
637 		(*func)();
638 }  /* end of willoption */
639 
640 void
641 send_dont(int option, int init)
642 {
643 	if (init) {
644 		if ((do_dont_resp[option] == 0 && his_state_is_wont(option)) ||
645 		    his_want_state_is_wont(option))
646 			return;
647 		set_his_want_state_wont(option);
648 		do_dont_resp[option]++;
649 	}
650 	output_data((const char *)dont, option);
651 
652 	DIAG(TD_OPTIONS, printoption("td: send dont", option));
653 }
654 
655 void
656 wontoption(int option)
657 {
658 	/*
659 	 * Process client input.
660 	 */
661 
662 	DIAG(TD_OPTIONS, printoption("td: recv wont", option));
663 
664 	if (do_dont_resp[option]) {
665 		do_dont_resp[option]--;
666 		if (do_dont_resp[option] && his_state_is_wont(option))
667 			do_dont_resp[option]--;
668 	}
669 	if (do_dont_resp[option] == 0) {
670 	    if (his_want_state_is_will(option)) {
671 		/* it is always ok to change to negative state */
672 		switch (option) {
673 		case TELOPT_ECHO:
674 			not42 = 1; /* doesn't seem to be a 4.2 system */
675 			break;
676 
677 		case TELOPT_BINARY:
678 			init_termbuf();
679 			tty_binaryin(0);
680 			set_termbuf();
681 			break;
682 
683 #ifdef	LINEMODE
684 		case TELOPT_LINEMODE:
685 # ifdef	KLUDGELINEMODE
686 			/*
687 			 * If real linemode is supported, then client is
688 			 * asking to turn linemode off.
689 			 */
690 			if (lmodetype != REAL_LINEMODE)
691 				break;
692 			lmodetype = KLUDGE_LINEMODE;
693 # endif	/* KLUDGELINEMODE */
694 			clientstat(TELOPT_LINEMODE, WONT, 0);
695 			break;
696 #endif	/* LINEMODE */
697 
698 		case TELOPT_TM:
699 			/*
700 			 * If we get a WONT TM, and had sent a DO TM,
701 			 * don't respond with a DONT TM, just leave it
702 			 * as is.  Short circut the state machine to
703 			 * achive this.
704 			 */
705 			set_his_want_state_wont(TELOPT_TM);
706 			return;
707 
708 		case TELOPT_LFLOW:
709 			/*
710 			 * If we are not going to support flow control
711 			 * option, then let peer know that we can't
712 			 * change the flow control characters.
713 			 */
714 			slctab[SLC_XON].defset.flag &= ~SLC_LEVELBITS;
715 			slctab[SLC_XON].defset.flag |= SLC_CANTCHANGE;
716 			slctab[SLC_XOFF].defset.flag &= ~SLC_LEVELBITS;
717 			slctab[SLC_XOFF].defset.flag |= SLC_CANTCHANGE;
718 			break;
719 
720 #ifdef	AUTHENTICATION
721 		case TELOPT_AUTHENTICATION:
722 			auth_finished(0, AUTH_REJECT);
723 			break;
724 #endif
725 
726 		/*
727 		 * For options that we might spin waiting for
728 		 * sub-negotiation, if the client turns off the
729 		 * option rather than responding to the request,
730 		 * we have to treat it here as if we got a response
731 		 * to the sub-negotiation, (by updating the timers)
732 		 * so that we'll break out of the loop.
733 		 */
734 		case TELOPT_TTYPE:
735 			settimer(ttypesubopt);
736 			break;
737 
738 		case TELOPT_TSPEED:
739 			settimer(tspeedsubopt);
740 			break;
741 
742 		case TELOPT_XDISPLOC:
743 			settimer(xdisplocsubopt);
744 			break;
745 
746 		case TELOPT_OLD_ENVIRON:
747 			settimer(oenvironsubopt);
748 			break;
749 
750 		case TELOPT_NEW_ENVIRON:
751 			settimer(environsubopt);
752 			break;
753 
754 		default:
755 			break;
756 		}
757 		set_his_want_state_wont(option);
758 		if (his_state_is_will(option))
759 			send_dont(option, 0);
760 	    } else {
761 		switch (option) {
762 		case TELOPT_TM:
763 #if	defined(LINEMODE) && defined(KLUDGELINEMODE)
764 			if (lmodetype < NO_AUTOKLUDGE) {
765 				lmodetype = NO_LINEMODE;
766 				clientstat(TELOPT_LINEMODE, WONT, 0);
767 				send_will(TELOPT_SGA, 1);
768 				send_will(TELOPT_ECHO, 1);
769 			}
770 #endif	/* defined(LINEMODE) && defined(KLUDGELINEMODE) */
771 			break;
772 
773 #ifdef AUTHENTICATION
774 		case TELOPT_AUTHENTICATION:
775 			auth_finished(0, AUTH_REJECT);
776 			break;
777 #endif
778 		default:
779 			break;
780 		}
781 	    }
782 	}
783 	set_his_state_wont(option);
784 
785 }  /* end of wontoption */
786 
787 void
788 send_will(int option, int init)
789 {
790 	if (init) {
791 		if ((will_wont_resp[option] == 0 && my_state_is_will(option))||
792 		    my_want_state_is_will(option))
793 			return;
794 		set_my_want_state_will(option);
795 		will_wont_resp[option]++;
796 	}
797 	output_data((const char *)will, option);
798 
799 	DIAG(TD_OPTIONS, printoption("td: send will", option));
800 }
801 
802 #if	!defined(LINEMODE) || !defined(KLUDGELINEMODE)
803 /*
804  * When we get a DONT SGA, we will try once to turn it
805  * back on.  If the other side responds DONT SGA, we
806  * leave it at that.  This is so that when we talk to
807  * clients that understand KLUDGELINEMODE but not LINEMODE,
808  * we'll keep them in char-at-a-time mode.
809  */
810 int turn_on_sga = 0;
811 #endif
812 
813 void
814 dooption(int option)
815 {
816 	int changeok = 0;
817 
818 	/*
819 	 * Process client input.
820 	 */
821 
822 	DIAG(TD_OPTIONS, printoption("td: recv do", option));
823 
824 	if (will_wont_resp[option]) {
825 		will_wont_resp[option]--;
826 		if (will_wont_resp[option] && my_state_is_will(option))
827 			will_wont_resp[option]--;
828 	}
829 	if ((will_wont_resp[option] == 0) && (my_want_state_is_wont(option))) {
830 		switch (option) {
831 		case TELOPT_ECHO:
832 #ifdef	LINEMODE
833 # ifdef	KLUDGELINEMODE
834 			if (lmodetype == NO_LINEMODE)
835 # else
836 			if (his_state_is_wont(TELOPT_LINEMODE))
837 # endif
838 #endif
839 			{
840 				init_termbuf();
841 				tty_setecho(1);
842 				set_termbuf();
843 			}
844 			changeok++;
845 			break;
846 
847 		case TELOPT_BINARY:
848 			init_termbuf();
849 			tty_binaryout(1);
850 			set_termbuf();
851 			changeok++;
852 			break;
853 
854 		case TELOPT_SGA:
855 #if	defined(LINEMODE) && defined(KLUDGELINEMODE)
856 			/*
857 			 * If kludge linemode is in use, then we must
858 			 * process an incoming do SGA for linemode
859 			 * purposes.
860 			 */
861 			if (lmodetype == KLUDGE_LINEMODE) {
862 				/*
863 				 * Receipt of "do SGA" in kludge
864 				 * linemode is the peer asking us to
865 				 * turn off linemode.  Make note of
866 				 * the request.
867 				 */
868 				clientstat(TELOPT_LINEMODE, WONT, 0);
869 				/*
870 				 * If linemode did not get turned off
871 				 * then don't tell peer that we did.
872 				 * Breaking here forces a wont SGA to
873 				 * be returned.
874 				 */
875 				if (linemode)
876 					break;
877 			}
878 #else
879 			turn_on_sga = 0;
880 #endif	/* defined(LINEMODE) && defined(KLUDGELINEMODE) */
881 			changeok++;
882 			break;
883 
884 		case TELOPT_STATUS:
885 			changeok++;
886 			break;
887 
888 		case TELOPT_TM:
889 			/*
890 			 * Special case for TM.  We send a WILL, but
891 			 * pretend we sent a WONT.
892 			 */
893 			send_will(option, 0);
894 			set_my_want_state_wont(option);
895 			set_my_state_wont(option);
896 			return;
897 
898 		case TELOPT_LOGOUT:
899 			/*
900 			 * When we get a LOGOUT option, respond
901 			 * with a WILL LOGOUT, make sure that
902 			 * it gets written out to the network,
903 			 * and then just go away...
904 			 */
905 			set_my_want_state_will(TELOPT_LOGOUT);
906 			send_will(TELOPT_LOGOUT, 0);
907 			set_my_state_will(TELOPT_LOGOUT);
908 			(void)netflush();
909 			cleanup(0);
910 			/* NOT REACHED */
911 			break;
912 
913 #ifdef	ENCRYPTION
914 		case TELOPT_ENCRYPT:
915 			changeok++;
916 			break;
917 #endif	/* ENCRYPTION */
918 		case TELOPT_LINEMODE:
919 		case TELOPT_TTYPE:
920 		case TELOPT_NAWS:
921 		case TELOPT_TSPEED:
922 		case TELOPT_LFLOW:
923 		case TELOPT_XDISPLOC:
924 #ifdef	TELOPT_ENVIRON
925 		case TELOPT_NEW_ENVIRON:
926 #endif
927 		case TELOPT_OLD_ENVIRON:
928 		default:
929 			break;
930 		}
931 		if (changeok) {
932 			set_my_want_state_will(option);
933 			send_will(option, 0);
934 		} else {
935 			will_wont_resp[option]++;
936 			send_wont(option, 0);
937 		}
938 	}
939 	set_my_state_will(option);
940 
941 }  /* end of dooption */
942 
943 void
944 send_wont(int option, int init)
945 {
946 	if (init) {
947 		if ((will_wont_resp[option] == 0 && my_state_is_wont(option)) ||
948 		    my_want_state_is_wont(option))
949 			return;
950 		set_my_want_state_wont(option);
951 		will_wont_resp[option]++;
952 	}
953 	output_data((const char *)wont, option);
954 
955 	DIAG(TD_OPTIONS, printoption("td: send wont", option));
956 }
957 
958 void
959 dontoption(int option)
960 {
961 	/*
962 	 * Process client input.
963 	 */
964 
965 
966 	DIAG(TD_OPTIONS, printoption("td: recv dont", option));
967 
968 	if (will_wont_resp[option]) {
969 		will_wont_resp[option]--;
970 		if (will_wont_resp[option] && my_state_is_wont(option))
971 			will_wont_resp[option]--;
972 	}
973 	if ((will_wont_resp[option] == 0) && (my_want_state_is_will(option))) {
974 		switch (option) {
975 		case TELOPT_BINARY:
976 			init_termbuf();
977 			tty_binaryout(0);
978 			set_termbuf();
979 			break;
980 
981 		case TELOPT_ECHO:	/* we should stop echoing */
982 #ifdef	LINEMODE
983 # ifdef	KLUDGELINEMODE
984 			if ((lmodetype != REAL_LINEMODE) &&
985 			    (lmodetype != KLUDGE_LINEMODE))
986 # else
987 			if (his_state_is_wont(TELOPT_LINEMODE))
988 # endif
989 #endif
990 			{
991 				init_termbuf();
992 				tty_setecho(0);
993 				set_termbuf();
994 			}
995 			break;
996 
997 		case TELOPT_SGA:
998 #if	defined(LINEMODE) && defined(KLUDGELINEMODE)
999 			/*
1000 			 * If kludge linemode is in use, then we
1001 			 * must process an incoming do SGA for
1002 			 * linemode purposes.
1003 			 */
1004 			if ((lmodetype == KLUDGE_LINEMODE) ||
1005 			    (lmodetype == KLUDGE_OK)) {
1006 				/*
1007 				 * The client is asking us to turn
1008 				 * linemode on.
1009 				 */
1010 				lmodetype = KLUDGE_LINEMODE;
1011 				clientstat(TELOPT_LINEMODE, WILL, 0);
1012 				/*
1013 				 * If we did not turn line mode on,
1014 				 * then what do we say?  Will SGA?
1015 				 * This violates design of telnet.
1016 				 * Gross.  Very Gross.
1017 				 */
1018 			}
1019 			break;
1020 #else
1021 			set_my_want_state_wont(option);
1022 			if (my_state_is_will(option))
1023 				send_wont(option, 0);
1024 			set_my_state_wont(option);
1025 			if (turn_on_sga ^= 1)
1026 				send_will(option, 1);
1027 			return;
1028 #endif	/* defined(LINEMODE) && defined(KLUDGELINEMODE) */
1029 
1030 		default:
1031 			break;
1032 		}
1033 
1034 		set_my_want_state_wont(option);
1035 		if (my_state_is_will(option))
1036 			send_wont(option, 0);
1037 	}
1038 	set_my_state_wont(option);
1039 
1040 }  /* end of dontoption */
1041 
1042 #ifdef	ENV_HACK
1043 int env_ovar = -1;
1044 int env_ovalue = -1;
1045 #else	/* ENV_HACK */
1046 # define env_ovar OLD_ENV_VAR
1047 # define env_ovalue OLD_ENV_VALUE
1048 #endif	/* ENV_HACK */
1049 
1050 /*
1051  * suboption()
1052  *
1053  *	Look at the sub-option buffer, and try to be helpful to the other
1054  * side.
1055  *
1056  *	Currently we recognize:
1057  *
1058  *	Terminal type is
1059  *	Linemode
1060  *	Window size
1061  *	Terminal speed
1062  */
1063 void
1064 suboption(void)
1065 {
1066     int subchar;
1067 
1068     DIAG(TD_OPTIONS, {netflush(); printsub('<', subpointer, SB_LEN()+2);});
1069 
1070     subchar = SB_GET();
1071     switch (subchar) {
1072     case TELOPT_TSPEED: {
1073 	int xspeed, rspeed;
1074 
1075 	if (his_state_is_wont(TELOPT_TSPEED))	/* Ignore if option disabled */
1076 		break;
1077 
1078 	settimer(tspeedsubopt);
1079 
1080 	if (SB_EOF() || SB_GET() != TELQUAL_IS)
1081 		return;
1082 
1083 	xspeed = atoi((char *)subpointer);
1084 
1085 	while (SB_GET() != ',' && !SB_EOF());
1086 	if (SB_EOF())
1087 		return;
1088 
1089 	rspeed = atoi((char *)subpointer);
1090 	clientstat(TELOPT_TSPEED, xspeed, rspeed);
1091 
1092 	break;
1093 
1094     }  /* end of case TELOPT_TSPEED */
1095 
1096     case TELOPT_TTYPE: {		/* Yaaaay! */
1097 	static char terminalname[41];
1098 
1099 	if (his_state_is_wont(TELOPT_TTYPE))	/* Ignore if option disabled */
1100 		break;
1101 	settimer(ttypesubopt);
1102 
1103 	if (SB_EOF() || SB_GET() != TELQUAL_IS) {
1104 	    return;		/* ??? XXX but, this is the most robust */
1105 	}
1106 
1107 	terminaltype = terminalname;
1108 
1109 	while ((terminaltype < (terminalname + sizeof terminalname-1)) &&
1110 								    !SB_EOF()) {
1111 	    int c;
1112 
1113 	    c = SB_GET();
1114 	    if (isupper(c)) {
1115 		c = tolower(c);
1116 	    }
1117 	    *terminaltype++ = c;    /* accumulate name */
1118 	}
1119 	*terminaltype = 0;
1120 	terminaltype = terminalname;
1121 	break;
1122     }  /* end of case TELOPT_TTYPE */
1123 
1124     case TELOPT_NAWS: {
1125 	int xwinsize, ywinsize;
1126 
1127 	if (his_state_is_wont(TELOPT_NAWS))	/* Ignore if option disabled */
1128 		break;
1129 
1130 	if (SB_EOF())
1131 		return;
1132 	xwinsize = SB_GET() << 8;
1133 	if (SB_EOF())
1134 		return;
1135 	xwinsize |= SB_GET();
1136 	if (SB_EOF())
1137 		return;
1138 	ywinsize = SB_GET() << 8;
1139 	if (SB_EOF())
1140 		return;
1141 	ywinsize |= SB_GET();
1142 	clientstat(TELOPT_NAWS, xwinsize, ywinsize);
1143 
1144 	break;
1145 
1146     }  /* end of case TELOPT_NAWS */
1147 
1148 #ifdef	LINEMODE
1149     case TELOPT_LINEMODE: {
1150 	int request;
1151 
1152 	if (his_state_is_wont(TELOPT_LINEMODE))	/* Ignore if option disabled */
1153 		break;
1154 	/*
1155 	 * Process linemode suboptions.
1156 	 */
1157 	if (SB_EOF())
1158 	    break;		/* garbage was sent */
1159 	request = SB_GET();	/* get will/wont */
1160 
1161 	if (SB_EOF())
1162 	    break;		/* another garbage check */
1163 
1164 	if (request == LM_SLC) {  /* SLC is not preceeded by WILL or WONT */
1165 		/*
1166 		 * Process suboption buffer of slc's
1167 		 */
1168 		start_slc(1);
1169 		do_opt_slc(subpointer, subend - subpointer);
1170 		(void) end_slc(0);
1171 		break;
1172 	} else if (request == LM_MODE) {
1173 		if (SB_EOF())
1174 		    return;
1175 		useeditmode = SB_GET();  /* get mode flag */
1176 		clientstat(LM_MODE, 0, 0);
1177 		break;
1178 	}
1179 
1180 	if (SB_EOF())
1181 	    break;
1182 	switch (SB_GET()) {  /* what suboption? */
1183 	case LM_FORWARDMASK:
1184 		/*
1185 		 * According to spec, only server can send request for
1186 		 * forwardmask, and client can only return a positive response.
1187 		 * So don't worry about it.
1188 		 */
1189 
1190 	default:
1191 		break;
1192 	}
1193 	break;
1194     }  /* end of case TELOPT_LINEMODE */
1195 #endif
1196     case TELOPT_STATUS: {
1197 	int mode;
1198 
1199 	if (SB_EOF())
1200 	    break;
1201 	mode = SB_GET();
1202 	switch (mode) {
1203 	case TELQUAL_SEND:
1204 	    if (my_state_is_will(TELOPT_STATUS))
1205 		send_status();
1206 	    break;
1207 
1208 	case TELQUAL_IS:
1209 	    break;
1210 
1211 	default:
1212 	    break;
1213 	}
1214 	break;
1215     }  /* end of case TELOPT_STATUS */
1216 
1217     case TELOPT_XDISPLOC: {
1218 	if (SB_EOF() || SB_GET() != TELQUAL_IS)
1219 		return;
1220 	settimer(xdisplocsubopt);
1221 	subpointer[SB_LEN()] = '\0';
1222 	(void)setenv("DISPLAY", (char *)subpointer, 1);
1223 	break;
1224     }  /* end of case TELOPT_XDISPLOC */
1225 
1226 #ifdef	TELOPT_NEW_ENVIRON
1227     case TELOPT_NEW_ENVIRON:
1228 #endif
1229     case TELOPT_OLD_ENVIRON: {
1230 	int c;
1231 	char *cp, *varp, *valp;
1232 
1233 	if (SB_EOF())
1234 		return;
1235 	c = SB_GET();
1236 	if (c == TELQUAL_IS) {
1237 		if (subchar == TELOPT_OLD_ENVIRON)
1238 			settimer(oenvironsubopt);
1239 		else
1240 			settimer(environsubopt);
1241 	} else if (c != TELQUAL_INFO) {
1242 		return;
1243 	}
1244 
1245 #ifdef	TELOPT_NEW_ENVIRON
1246 	if (subchar == TELOPT_NEW_ENVIRON) {
1247 	    while (!SB_EOF()) {
1248 		c = SB_GET();
1249 		if ((c == NEW_ENV_VAR) || (c == ENV_USERVAR))
1250 			break;
1251 	    }
1252 	} else
1253 #endif
1254 	{
1255 #ifdef	ENV_HACK
1256 	    /*
1257 	     * We only want to do this if we haven't already decided
1258 	     * whether or not the other side has its VALUE and VAR
1259 	     * reversed.
1260 	     */
1261 	    if (env_ovar < 0) {
1262 		int last = -1;		/* invalid value */
1263 		int empty = 0;
1264 		int got_var = 0, got_value = 0, got_uservar = 0;
1265 
1266 		/*
1267 		 * The other side might have its VALUE and VAR values
1268 		 * reversed.  To be interoperable, we need to determine
1269 		 * which way it is.  If the first recognized character
1270 		 * is a VAR or VALUE, then that will tell us what
1271 		 * type of client it is.  If the fist recognized
1272 		 * character is a USERVAR, then we continue scanning
1273 		 * the suboption looking for two consecutive
1274 		 * VAR or VALUE fields.  We should not get two
1275 		 * consecutive VALUE fields, so finding two
1276 		 * consecutive VALUE or VAR fields will tell us
1277 		 * what the client is.
1278 		 */
1279 		SB_SAVE();
1280 		while (!SB_EOF()) {
1281 			c = SB_GET();
1282 			switch(c) {
1283 			case OLD_ENV_VAR:
1284 				if (last < 0 || last == OLD_ENV_VAR
1285 				    || (empty && (last == OLD_ENV_VALUE)))
1286 					goto env_ovar_ok;
1287 				got_var++;
1288 				last = OLD_ENV_VAR;
1289 				break;
1290 			case OLD_ENV_VALUE:
1291 				if (last < 0 || last == OLD_ENV_VALUE
1292 				    || (empty && (last == OLD_ENV_VAR)))
1293 					goto env_ovar_wrong;
1294 				got_value++;
1295 				last = OLD_ENV_VALUE;
1296 				break;
1297 			case ENV_USERVAR:
1298 				/* count strings of USERVAR as one */
1299 				if (last != ENV_USERVAR)
1300 					got_uservar++;
1301 				if (empty) {
1302 					if (last == OLD_ENV_VALUE)
1303 						goto env_ovar_ok;
1304 					if (last == OLD_ENV_VAR)
1305 						goto env_ovar_wrong;
1306 				}
1307 				last = ENV_USERVAR;
1308 				break;
1309 			case ENV_ESC:
1310 				if (!SB_EOF())
1311 					c = SB_GET();
1312 				/* FALLTHROUGH */
1313 			default:
1314 				empty = 0;
1315 				continue;
1316 			}
1317 			empty = 1;
1318 		}
1319 		if (empty) {
1320 			if (last == OLD_ENV_VALUE)
1321 				goto env_ovar_ok;
1322 			if (last == OLD_ENV_VAR)
1323 				goto env_ovar_wrong;
1324 		}
1325 		/*
1326 		 * Ok, the first thing was a USERVAR, and there
1327 		 * are not two consecutive VAR or VALUE commands,
1328 		 * and none of the VAR or VALUE commands are empty.
1329 		 * If the client has sent us a well-formed option,
1330 		 * then the number of VALUEs received should always
1331 		 * be less than or equal to the number of VARs and
1332 		 * USERVARs received.
1333 		 *
1334 		 * If we got exactly as many VALUEs as VARs and
1335 		 * USERVARs, the client has the same definitions.
1336 		 *
1337 		 * If we got exactly as many VARs as VALUEs and
1338 		 * USERVARS, the client has reversed definitions.
1339 		 */
1340 		if (got_uservar + got_var == got_value) {
1341 	    env_ovar_ok:
1342 			env_ovar = OLD_ENV_VAR;
1343 			env_ovalue = OLD_ENV_VALUE;
1344 		} else if (got_uservar + got_value == got_var) {
1345 	    env_ovar_wrong:
1346 			env_ovar = OLD_ENV_VALUE;
1347 			env_ovalue = OLD_ENV_VAR;
1348 			DIAG(TD_OPTIONS,
1349 			    output_data("ENVIRON VALUE and VAR are reversed!\r\n"));
1350 
1351 		}
1352 	    }
1353 	    SB_RESTORE();
1354 #endif
1355 
1356 	    while (!SB_EOF()) {
1357 		c = SB_GET();
1358 		if ((c == env_ovar) || (c == ENV_USERVAR))
1359 			break;
1360 	    }
1361 	}
1362 
1363 	if (SB_EOF())
1364 		return;
1365 
1366 	cp = varp = (char *)subpointer;
1367 	valp = 0;
1368 
1369 	while (!SB_EOF()) {
1370 		c = SB_GET();
1371 		if (subchar == TELOPT_OLD_ENVIRON) {
1372 			if (c == env_ovar)
1373 				c = NEW_ENV_VAR;
1374 			else if (c == env_ovalue)
1375 				c = NEW_ENV_VALUE;
1376 		}
1377 		switch (c) {
1378 
1379 		case NEW_ENV_VALUE:
1380 			*cp = '\0';
1381 			cp = valp = (char *)subpointer;
1382 			break;
1383 
1384 		case NEW_ENV_VAR:
1385 		case ENV_USERVAR:
1386 			*cp = '\0';
1387 			if (valp)
1388 				(void)setenv(varp, valp, 1);
1389 			else
1390 				unsetenv(varp);
1391 			cp = varp = (char *)subpointer;
1392 			valp = 0;
1393 			break;
1394 
1395 		case ENV_ESC:
1396 			if (SB_EOF())
1397 				break;
1398 			c = SB_GET();
1399 			/* FALLTHROUGH */
1400 		default:
1401 			*cp++ = c;
1402 			break;
1403 		}
1404 	}
1405 	*cp = '\0';
1406 	if (valp)
1407 		(void)setenv(varp, valp, 1);
1408 	else
1409 		unsetenv(varp);
1410 	break;
1411     }  /* end of case TELOPT_NEW_ENVIRON */
1412 #ifdef	AUTHENTICATION
1413     case TELOPT_AUTHENTICATION:
1414 	if (SB_EOF())
1415 		break;
1416 	switch(SB_GET()) {
1417 	case TELQUAL_SEND:
1418 	case TELQUAL_REPLY:
1419 		/*
1420 		 * These are sent by us and cannot be sent by
1421 		 * the client.
1422 		 */
1423 		break;
1424 	case TELQUAL_IS:
1425 		auth_is(subpointer, SB_LEN());
1426 		break;
1427 	case TELQUAL_NAME:
1428 		auth_name(subpointer, SB_LEN());
1429 		break;
1430 	}
1431 	break;
1432 #endif
1433 #ifdef	ENCRYPTION
1434     case TELOPT_ENCRYPT:
1435 	if (SB_EOF())
1436 		break;
1437 	switch(SB_GET()) {
1438 	case ENCRYPT_SUPPORT:
1439 		encrypt_support(subpointer, SB_LEN());
1440 		break;
1441 	case ENCRYPT_IS:
1442 		encrypt_is(subpointer, SB_LEN());
1443 		break;
1444 	case ENCRYPT_REPLY:
1445 		encrypt_reply(subpointer, SB_LEN());
1446 		break;
1447 	case ENCRYPT_START:
1448 		encrypt_start(subpointer, SB_LEN());
1449 		break;
1450 	case ENCRYPT_END:
1451 		encrypt_end();
1452 		break;
1453 	case ENCRYPT_REQSTART:
1454 		encrypt_request_start(subpointer, SB_LEN());
1455 		break;
1456 	case ENCRYPT_REQEND:
1457 		/*
1458 		 * We can always send an REQEND so that we cannot
1459 		 * get stuck encrypting.  We should only get this
1460 		 * if we have been able to get in the correct mode
1461 		 * anyhow.
1462 		 */
1463 		encrypt_request_end();
1464 		break;
1465 	case ENCRYPT_ENC_KEYID:
1466 		encrypt_enc_keyid(subpointer, SB_LEN());
1467 		break;
1468 	case ENCRYPT_DEC_KEYID:
1469 		encrypt_dec_keyid(subpointer, SB_LEN());
1470 		break;
1471 	default:
1472 		break;
1473 	}
1474 	break;
1475 #endif	/* ENCRYPTION */
1476 
1477     default:
1478 	break;
1479     }  /* end of switch */
1480 
1481 }  /* end of suboption */
1482 
1483 static void
1484 doclientstat(void)
1485 {
1486 	clientstat(TELOPT_LINEMODE, WILL, 0);
1487 }
1488 
1489 #define	ADD(c)	 *ncp++ = c
1490 #define	ADD_DATA(c) { *ncp++ = c; if (c == SE || c == IAC) *ncp++ = c; }
1491 void
1492 send_status(void)
1493 {
1494 	unsigned char statusbuf[256];
1495 	unsigned char *ncp;
1496 	unsigned char i;
1497 
1498 	ncp = statusbuf;
1499 
1500 	netflush();	/* get rid of anything waiting to go out */
1501 
1502 	ADD(IAC);
1503 	ADD(SB);
1504 	ADD(TELOPT_STATUS);
1505 	ADD(TELQUAL_IS);
1506 
1507 	/*
1508 	 * We check the want_state rather than the current state,
1509 	 * because if we received a DO/WILL for an option that we
1510 	 * don't support, and the other side didn't send a DONT/WONT
1511 	 * in response to our WONT/DONT, then the "state" will be
1512 	 * WILL/DO, and the "want_state" will be WONT/DONT.  We
1513 	 * need to go by the latter.
1514 	 */
1515 	for (i = 0; i < (unsigned char)NTELOPTS; i++) {
1516 		if (my_want_state_is_will(i)) {
1517 			ADD(WILL);
1518 			ADD_DATA(i);
1519 			if (i == IAC)
1520 				ADD(IAC);
1521 		}
1522 		if (his_want_state_is_will(i)) {
1523 			ADD(DO);
1524 			ADD_DATA(i);
1525 			if (i == IAC)
1526 				ADD(IAC);
1527 		}
1528 	}
1529 
1530 	if (his_want_state_is_will(TELOPT_LFLOW)) {
1531 		ADD(SB);
1532 		ADD(TELOPT_LFLOW);
1533 		if (flowmode) {
1534 			ADD(LFLOW_ON);
1535 		} else {
1536 			ADD(LFLOW_OFF);
1537 		}
1538 		ADD(SE);
1539 
1540 		if (restartany >= 0) {
1541 			ADD(SB);
1542 			ADD(TELOPT_LFLOW);
1543 			if (restartany) {
1544 				ADD(LFLOW_RESTART_ANY);
1545 			} else {
1546 				ADD(LFLOW_RESTART_XON);
1547 			}
1548 			ADD(SE);
1549 		}
1550 	}
1551 
1552 #ifdef	LINEMODE
1553 	if (his_want_state_is_will(TELOPT_LINEMODE)) {
1554 		unsigned char *cp, *cpe;
1555 		int len;
1556 
1557 		ADD(SB);
1558 		ADD(TELOPT_LINEMODE);
1559 		ADD(LM_MODE);
1560 		ADD_DATA(editmode);
1561 		ADD(SE);
1562 
1563 		ADD(SB);
1564 		ADD(TELOPT_LINEMODE);
1565 		ADD(LM_SLC);
1566 		start_slc(0);
1567 		send_slc();
1568 		len = end_slc(&cp);
1569 		for (cpe = cp + len; cp < cpe; cp++)
1570 			ADD_DATA(*cp);
1571 		ADD(SE);
1572 	}
1573 #endif	/* LINEMODE */
1574 
1575 	ADD(IAC);
1576 	ADD(SE);
1577 
1578 	output_datalen(statusbuf, ncp - statusbuf);
1579 	netflush();	/* Send it on its way */
1580 
1581 	DIAG(TD_OPTIONS,
1582 		{printsub('>', statusbuf, ncp - statusbuf); netflush();});
1583 }
1584 
1585 /*
1586  * This function appends data to nfrontp and advances nfrontp.
1587  * Returns the number of characters written altogether (the
1588  * buffer may have been flushed in the process).
1589  */
1590 
1591 int
1592 output_data(const char *format, ...)
1593 {
1594 	va_list args;
1595 	int len;
1596 	char *buf;
1597 
1598 	va_start(args, format);
1599 	if ((len = vasprintf(&buf, format, args)) == -1) {
1600 		va_end(args);
1601 		return -1;
1602 	}
1603 	output_datalen(buf, len);
1604 	va_end(args);
1605 	free(buf);
1606 	return (len);
1607 }
1608 
1609 void
1610 output_datalen(const char *buf, int len)
1611 {
1612 	int remaining, copied;
1613 
1614 	remaining = BUFSIZ - (nfrontp - netobuf);
1615 	while (len > 0) {
1616 		/* Free up enough space if the room is too low*/
1617 		if ((len > BUFSIZ ? BUFSIZ : len) > remaining) {
1618 			netflush();
1619 			remaining = BUFSIZ - (nfrontp - netobuf);
1620 		}
1621 
1622 		/* Copy out as much as will fit */
1623 		copied = remaining > len ? len : remaining;
1624 		memmove(nfrontp, buf, copied);
1625 		nfrontp += copied;
1626 		len -= copied;
1627 		remaining -= copied;
1628 		buf += copied;
1629 	}
1630 	return;
1631 }
1632