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`realhost', passed back from all the backend init functions, was
[u/mdw/putty] / telnet.c
1 #include <windows.h>
2 #include <stdio.h>
3 #include <stdlib.h>
4
5 #include "putty.h"
6
7 #ifndef FALSE
8 #define FALSE 0
9 #endif
10 #ifndef TRUE
11 #define TRUE 1
12 #endif
13
14 static Socket s = NULL;
15
16 #define IAC 255 /* interpret as command: */
17 #define DONT 254 /* you are not to use option */
18 #define DO 253 /* please, you use option */
19 #define WONT 252 /* I won't use option */
20 #define WILL 251 /* I will use option */
21 #define SB 250 /* interpret as subnegotiation */
22 #define SE 240 /* end sub negotiation */
23
24 #define GA 249 /* you may reverse the line */
25 #define EL 248 /* erase the current line */
26 #define EC 247 /* erase the current character */
27 #define AYT 246 /* are you there */
28 #define AO 245 /* abort output--but let prog finish */
29 #define IP 244 /* interrupt process--permanently */
30 #define BREAK 243 /* break */
31 #define DM 242 /* data mark--for connect. cleaning */
32 #define NOP 241 /* nop */
33 #define EOR 239 /* end of record (transparent mode) */
34 #define ABORT 238 /* Abort process */
35 #define SUSP 237 /* Suspend process */
36 #define xEOF 236 /* End of file: EOF is already used... */
37
38 #define TELOPT_BINARY 0 /* 8-bit data path */
39 #define TELOPT_ECHO 1 /* echo */
40 #define TELOPT_RCP 2 /* prepare to reconnect */
41 #define TELOPT_SGA 3 /* suppress go ahead */
42 #define TELOPT_NAMS 4 /* approximate message size */
43 #define TELOPT_STATUS 5 /* give status */
44 #define TELOPT_TM 6 /* timing mark */
45 #define TELOPT_RCTE 7 /* remote controlled transmission and echo */
46 #define TELOPT_NAOL 8 /* negotiate about output line width */
47 #define TELOPT_NAOP 9 /* negotiate about output page size */
48 #define TELOPT_NAOCRD 10 /* negotiate about CR disposition */
49 #define TELOPT_NAOHTS 11 /* negotiate about horizontal tabstops */
50 #define TELOPT_NAOHTD 12 /* negotiate about horizontal tab disposition */
51 #define TELOPT_NAOFFD 13 /* negotiate about formfeed disposition */
52 #define TELOPT_NAOVTS 14 /* negotiate about vertical tab stops */
53 #define TELOPT_NAOVTD 15 /* negotiate about vertical tab disposition */
54 #define TELOPT_NAOLFD 16 /* negotiate about output LF disposition */
55 #define TELOPT_XASCII 17 /* extended ascic character set */
56 #define TELOPT_LOGOUT 18 /* force logout */
57 #define TELOPT_BM 19 /* byte macro */
58 #define TELOPT_DET 20 /* data entry terminal */
59 #define TELOPT_SUPDUP 21 /* supdup protocol */
60 #define TELOPT_SUPDUPOUTPUT 22 /* supdup output */
61 #define TELOPT_SNDLOC 23 /* send location */
62 #define TELOPT_TTYPE 24 /* terminal type */
63 #define TELOPT_EOR 25 /* end or record */
64 #define TELOPT_TUID 26 /* TACACS user identification */
65 #define TELOPT_OUTMRK 27 /* output marking */
66 #define TELOPT_TTYLOC 28 /* terminal location number */
67 #define TELOPT_3270REGIME 29 /* 3270 regime */
68 #define TELOPT_X3PAD 30 /* X.3 PAD */
69 #define TELOPT_NAWS 31 /* window size */
70 #define TELOPT_TSPEED 32 /* terminal speed */
71 #define TELOPT_LFLOW 33 /* remote flow control */
72 #define TELOPT_LINEMODE 34 /* Linemode option */
73 #define TELOPT_XDISPLOC 35 /* X Display Location */
74 #define TELOPT_OLD_ENVIRON 36 /* Old - Environment variables */
75 #define TELOPT_AUTHENTICATION 37 /* Authenticate */
76 #define TELOPT_ENCRYPT 38 /* Encryption option */
77 #define TELOPT_NEW_ENVIRON 39 /* New - Environment variables */
78 #define TELOPT_EXOPL 255 /* extended-options-list */
79
80 #define TELQUAL_IS 0 /* option is... */
81 #define TELQUAL_SEND 1 /* send option */
82 #define TELQUAL_INFO 2 /* ENVIRON: informational version of IS */
83 #define BSD_VAR 1
84 #define BSD_VALUE 0
85 #define RFC_VAR 0
86 #define RFC_VALUE 1
87
88 #define CR 13
89 #define LF 10
90 #define NUL 0
91
92 #define iswritable(x) ( (x) != IAC && (x) != CR )
93
94 static char *telopt(int opt)
95 {
96 #define i(x) if (opt == TELOPT_ ## x) return #x;
97 i(BINARY);
98 i(ECHO);
99 i(RCP);
100 i(SGA);
101 i(NAMS);
102 i(STATUS);
103 i(TM);
104 i(RCTE);
105 i(NAOL);
106 i(NAOP);
107 i(NAOCRD);
108 i(NAOHTS);
109 i(NAOHTD);
110 i(NAOFFD);
111 i(NAOVTS);
112 i(NAOVTD);
113 i(NAOLFD);
114 i(XASCII);
115 i(LOGOUT);
116 i(BM);
117 i(DET);
118 i(SUPDUP);
119 i(SUPDUPOUTPUT);
120 i(SNDLOC);
121 i(TTYPE);
122 i(EOR);
123 i(TUID);
124 i(OUTMRK);
125 i(TTYLOC);
126 i(X3PAD);
127 i(NAWS);
128 i(TSPEED);
129 i(LFLOW);
130 i(LINEMODE);
131 i(XDISPLOC);
132 i(OLD_ENVIRON);
133 i(AUTHENTICATION);
134 i(ENCRYPT);
135 i(NEW_ENVIRON);
136 i(EXOPL);
137 #undef i
138 return "<unknown>";
139 }
140
141 static void telnet_size(void);
142
143 struct Opt {
144 int send; /* what we initially send */
145 int nsend; /* -ve send if requested to stop it */
146 int ack, nak; /* +ve and -ve acknowledgements */
147 int option; /* the option code */
148 enum {
149 REQUESTED, ACTIVE, INACTIVE, REALLY_INACTIVE
150 } state;
151 };
152
153 static struct Opt o_naws =
154 { WILL, WONT, DO, DONT, TELOPT_NAWS, REQUESTED };
155 static struct Opt o_tspeed =
156 { WILL, WONT, DO, DONT, TELOPT_TSPEED, REQUESTED };
157 static struct Opt o_ttype =
158 { WILL, WONT, DO, DONT, TELOPT_TTYPE, REQUESTED };
159 static struct Opt o_oenv = { WILL, WONT, DO, DONT, TELOPT_OLD_ENVIRON,
160 INACTIVE
161 };
162 static struct Opt o_nenv = { WILL, WONT, DO, DONT, TELOPT_NEW_ENVIRON,
163 REQUESTED
164 };
165 static struct Opt o_echo =
166 { DO, DONT, WILL, WONT, TELOPT_ECHO, REQUESTED };
167 static struct Opt o_we_sga =
168 { WILL, WONT, DO, DONT, TELOPT_SGA, REQUESTED };
169 static struct Opt o_they_sga =
170 { DO, DONT, WILL, WONT, TELOPT_SGA, REQUESTED };
171
172 static struct Opt *opts[] = {
173 &o_naws, &o_tspeed, &o_ttype, &o_oenv, &o_nenv, &o_echo,
174 &o_we_sga, &o_they_sga, NULL
175 };
176
177 static int echoing = TRUE, editing = TRUE;
178 static int activated = FALSE;
179
180 static int in_synch;
181 static int sb_opt, sb_len;
182 static char *sb_buf = NULL;
183 static int sb_size = 0;
184 #define SB_DELTA 1024
185
186 static void c_write1(int c)
187 {
188 char cc = (char) c;
189 from_backend(0, &cc, 1);
190 }
191
192 static void log_option(char *sender, int cmd, int option)
193 {
194 char buf[50];
195 sprintf(buf, "%s:\t%s %s", sender,
196 (cmd == WILL ? "WILL" : cmd == WONT ? "WONT" :
197 cmd == DO ? "DO" : cmd == DONT ? "DONT" : "<??>"),
198 telopt(option));
199 logevent(buf);
200 }
201
202 static void send_opt(int cmd, int option)
203 {
204 unsigned char b[3];
205
206 b[0] = IAC;
207 b[1] = cmd;
208 b[2] = option;
209 sk_write(s, b, 3);
210 log_option("client", cmd, option);
211 }
212
213 static void deactivate_option(struct Opt *o)
214 {
215 if (o->state == REQUESTED || o->state == ACTIVE)
216 send_opt(o->nsend, o->option);
217 o->state = REALLY_INACTIVE;
218 }
219
220 /*
221 * Generate side effects of enabling or disabling an option.
222 */
223 static void option_side_effects(struct Opt *o, int enabled)
224 {
225 if (o->option == TELOPT_ECHO && o->send == DO)
226 echoing = !enabled;
227 else if (o->option == TELOPT_SGA && o->send == DO)
228 editing = !enabled;
229 ldisc_send(NULL, 0); /* cause ldisc to notice the change */
230
231 /* Ensure we get the minimum options */
232 if (!activated) {
233 if (o_echo.state == INACTIVE) {
234 o_echo.state = REQUESTED;
235 send_opt(o_echo.send, o_echo.option);
236 }
237 if (o_we_sga.state == INACTIVE) {
238 o_we_sga.state = REQUESTED;
239 send_opt(o_we_sga.send, o_we_sga.option);
240 }
241 if (o_they_sga.state == INACTIVE) {
242 o_they_sga.state = REQUESTED;
243 send_opt(o_they_sga.send, o_they_sga.option);
244 }
245 activated = TRUE;
246 }
247 }
248
249 static void activate_option(struct Opt *o)
250 {
251 if (o->send == WILL && o->option == TELOPT_NAWS)
252 telnet_size();
253 if (o->send == WILL &&
254 (o->option == TELOPT_NEW_ENVIRON ||
255 o->option == TELOPT_OLD_ENVIRON)) {
256 /*
257 * We may only have one kind of ENVIRON going at a time.
258 * This is a hack, but who cares.
259 */
260 deactivate_option(o->option ==
261 TELOPT_NEW_ENVIRON ? &o_oenv : &o_nenv);
262 }
263 option_side_effects(o, 1);
264 }
265
266 static void refused_option(struct Opt *o)
267 {
268 if (o->send == WILL && o->option == TELOPT_NEW_ENVIRON &&
269 o_oenv.state == INACTIVE) {
270 send_opt(WILL, TELOPT_OLD_ENVIRON);
271 o_oenv.state = REQUESTED;
272 }
273 option_side_effects(o, 0);
274 }
275
276 static void proc_rec_opt(int cmd, int option)
277 {
278 struct Opt **o;
279
280 log_option("server", cmd, option);
281 for (o = opts; *o; o++) {
282 if ((*o)->option == option && (*o)->ack == cmd) {
283 switch ((*o)->state) {
284 case REQUESTED:
285 (*o)->state = ACTIVE;
286 activate_option(*o);
287 break;
288 case ACTIVE:
289 break;
290 case INACTIVE:
291 (*o)->state = ACTIVE;
292 send_opt((*o)->send, option);
293 activate_option(*o);
294 break;
295 case REALLY_INACTIVE:
296 send_opt((*o)->nsend, option);
297 break;
298 }
299 return;
300 } else if ((*o)->option == option && (*o)->nak == cmd) {
301 switch ((*o)->state) {
302 case REQUESTED:
303 (*o)->state = INACTIVE;
304 refused_option(*o);
305 break;
306 case ACTIVE:
307 (*o)->state = INACTIVE;
308 send_opt((*o)->nsend, option);
309 option_side_effects(*o, 0);
310 break;
311 case INACTIVE:
312 case REALLY_INACTIVE:
313 break;
314 }
315 return;
316 }
317 }
318 /*
319 * If we reach here, the option was one we weren't prepared to
320 * cope with. So send a negative ack.
321 */
322 send_opt((cmd == WILL ? DONT : WONT), option);
323 }
324
325 static void process_subneg(void)
326 {
327 unsigned char b[2048], *p, *q;
328 int var, value, n;
329 char *e;
330
331 switch (sb_opt) {
332 case TELOPT_TSPEED:
333 if (sb_len == 1 && sb_buf[0] == TELQUAL_SEND) {
334 char logbuf[sizeof(cfg.termspeed) + 80];
335 b[0] = IAC;
336 b[1] = SB;
337 b[2] = TELOPT_TSPEED;
338 b[3] = TELQUAL_IS;
339 strcpy(b + 4, cfg.termspeed);
340 n = 4 + strlen(cfg.termspeed);
341 b[n] = IAC;
342 b[n + 1] = SE;
343 sk_write(s, b, n + 2);
344 logevent("server:\tSB TSPEED SEND");
345 sprintf(logbuf, "client:\tSB TSPEED IS %s", cfg.termspeed);
346 logevent(logbuf);
347 } else
348 logevent("server:\tSB TSPEED <something weird>");
349 break;
350 case TELOPT_TTYPE:
351 if (sb_len == 1 && sb_buf[0] == TELQUAL_SEND) {
352 char logbuf[sizeof(cfg.termtype) + 80];
353 b[0] = IAC;
354 b[1] = SB;
355 b[2] = TELOPT_TTYPE;
356 b[3] = TELQUAL_IS;
357 for (n = 0; cfg.termtype[n]; n++)
358 b[n + 4] = (cfg.termtype[n] >= 'a'
359 && cfg.termtype[n] <=
360 'z' ? cfg.termtype[n] + 'A' -
361 'a' : cfg.termtype[n]);
362 b[n + 4] = IAC;
363 b[n + 5] = SE;
364 sk_write(s, b, n + 6);
365 b[n + 4] = 0;
366 logevent("server:\tSB TTYPE SEND");
367 sprintf(logbuf, "client:\tSB TTYPE IS %s", b + 4);
368 logevent(logbuf);
369 } else
370 logevent("server:\tSB TTYPE <something weird>\r\n");
371 break;
372 case TELOPT_OLD_ENVIRON:
373 case TELOPT_NEW_ENVIRON:
374 p = sb_buf;
375 q = p + sb_len;
376 if (p < q && *p == TELQUAL_SEND) {
377 char logbuf[50];
378 p++;
379 sprintf(logbuf, "server:\tSB %s SEND", telopt(sb_opt));
380 logevent(logbuf);
381 if (sb_opt == TELOPT_OLD_ENVIRON) {
382 if (cfg.rfc_environ) {
383 value = RFC_VALUE;
384 var = RFC_VAR;
385 } else {
386 value = BSD_VALUE;
387 var = BSD_VAR;
388 }
389 /*
390 * Try to guess the sense of VAR and VALUE.
391 */
392 while (p < q) {
393 if (*p == RFC_VAR) {
394 value = RFC_VALUE;
395 var = RFC_VAR;
396 } else if (*p == BSD_VAR) {
397 value = BSD_VALUE;
398 var = BSD_VAR;
399 }
400 p++;
401 }
402 } else {
403 /*
404 * With NEW_ENVIRON, the sense of VAR and VALUE
405 * isn't in doubt.
406 */
407 value = RFC_VALUE;
408 var = RFC_VAR;
409 }
410 b[0] = IAC;
411 b[1] = SB;
412 b[2] = sb_opt;
413 b[3] = TELQUAL_IS;
414 n = 4;
415 e = cfg.environmt;
416 while (*e) {
417 b[n++] = var;
418 while (*e && *e != '\t')
419 b[n++] = *e++;
420 if (*e == '\t')
421 e++;
422 b[n++] = value;
423 while (*e)
424 b[n++] = *e++;
425 e++;
426 }
427 if (*cfg.username) {
428 b[n++] = var;
429 b[n++] = 'U';
430 b[n++] = 'S';
431 b[n++] = 'E';
432 b[n++] = 'R';
433 b[n++] = value;
434 e = cfg.username;
435 while (*e)
436 b[n++] = *e++;
437 }
438 b[n++] = IAC;
439 b[n++] = SE;
440 sk_write(s, b, n);
441 sprintf(logbuf, "client:\tSB %s IS %s", telopt(sb_opt),
442 n == 6 ? "<nothing>" : "<stuff>");
443 logevent(logbuf);
444 }
445 break;
446 }
447 }
448
449 static enum {
450 TOPLEVEL, SEENIAC, SEENWILL, SEENWONT, SEENDO, SEENDONT,
451 SEENSB, SUBNEGOT, SUBNEG_IAC, SEENCR
452 } telnet_state = TOPLEVEL;
453
454 static void do_telnet_read(char *buf, int len)
455 {
456
457 while (len--) {
458 int c = (unsigned char) *buf++;
459
460 switch (telnet_state) {
461 case TOPLEVEL:
462 case SEENCR:
463 if (c == NUL && telnet_state == SEENCR)
464 telnet_state = TOPLEVEL;
465 else if (c == IAC)
466 telnet_state = SEENIAC;
467 else {
468 if (!in_synch)
469 c_write1(c);
470
471 #if 1
472 /* I can't get the F***ing winsock to insert the urgent IAC
473 * into the right position! Even with SO_OOBINLINE it gives
474 * it to recv too soon. And of course the DM byte (that
475 * arrives in the same packet!) appears several K later!!
476 *
477 * Oh well, we do get the DM in the right place so I'll
478 * just stop hiding on the next 0xf2 and hope for the best.
479 */
480 else if (c == DM)
481 in_synch = 0;
482 #endif
483 if (c == CR)
484 telnet_state = SEENCR;
485 else
486 telnet_state = TOPLEVEL;
487 }
488 break;
489 case SEENIAC:
490 if (c == DO)
491 telnet_state = SEENDO;
492 else if (c == DONT)
493 telnet_state = SEENDONT;
494 else if (c == WILL)
495 telnet_state = SEENWILL;
496 else if (c == WONT)
497 telnet_state = SEENWONT;
498 else if (c == SB)
499 telnet_state = SEENSB;
500 else if (c == DM) {
501 in_synch = 0;
502 telnet_state = TOPLEVEL;
503 } else {
504 /* ignore everything else; print it if it's IAC */
505 if (c == IAC) {
506 c_write1(c);
507 }
508 telnet_state = TOPLEVEL;
509 }
510 break;
511 case SEENWILL:
512 proc_rec_opt(WILL, c);
513 telnet_state = TOPLEVEL;
514 break;
515 case SEENWONT:
516 proc_rec_opt(WONT, c);
517 telnet_state = TOPLEVEL;
518 break;
519 case SEENDO:
520 proc_rec_opt(DO, c);
521 telnet_state = TOPLEVEL;
522 break;
523 case SEENDONT:
524 proc_rec_opt(DONT, c);
525 telnet_state = TOPLEVEL;
526 break;
527 case SEENSB:
528 sb_opt = c;
529 sb_len = 0;
530 telnet_state = SUBNEGOT;
531 break;
532 case SUBNEGOT:
533 if (c == IAC)
534 telnet_state = SUBNEG_IAC;
535 else {
536 subneg_addchar:
537 if (sb_len >= sb_size) {
538 char *newbuf;
539 sb_size += SB_DELTA;
540 newbuf = (sb_buf ?
541 srealloc(sb_buf, sb_size) :
542 smalloc(sb_size));
543 if (newbuf)
544 sb_buf = newbuf;
545 else
546 sb_size -= SB_DELTA;
547 }
548 if (sb_len < sb_size)
549 sb_buf[sb_len++] = c;
550 telnet_state = SUBNEGOT; /* in case we came here by goto */
551 }
552 break;
553 case SUBNEG_IAC:
554 if (c != SE)
555 goto subneg_addchar; /* yes, it's a hack, I know, but... */
556 else {
557 process_subneg();
558 telnet_state = TOPLEVEL;
559 }
560 break;
561 }
562 }
563 }
564
565 static int telnet_closing(Plug plug, char *error_msg, int error_code,
566 int calling_back)
567 {
568 sk_close(s);
569 s = NULL;
570 if (error_msg) {
571 /* A socket error has occurred. */
572 connection_fatal(error_msg);
573 } /* Otherwise, the remote side closed the connection normally. */
574 return 0;
575 }
576
577 static int telnet_receive(Plug plug, int urgent, char *data, int len)
578 {
579 if (urgent)
580 in_synch = TRUE;
581 do_telnet_read(data, len);
582 return 1;
583 }
584
585 /*
586 * Called to set up the Telnet connection.
587 *
588 * Returns an error message, or NULL on success.
589 *
590 * Also places the canonical host name into `realhost'. It must be
591 * freed by the caller.
592 */
593 static char *telnet_init(char *host, int port, char **realhost)
594 {
595 static struct plug_function_table fn_table = {
596 telnet_closing,
597 telnet_receive
598 }, *fn_table_ptr = &fn_table;
599
600 SockAddr addr;
601 char *err;
602
603 /*
604 * Try to find host.
605 */
606 addr = sk_namelookup(host, realhost);
607 if ((err = sk_addr_error(addr)))
608 return err;
609
610 if (port < 0)
611 port = 23; /* default telnet port */
612
613 /*
614 * Open socket.
615 */
616 s = sk_new(addr, port, 0, 1, &fn_table_ptr);
617 if ((err = sk_socket_error(s)))
618 return err;
619
620 sk_addr_free(addr);
621
622 /*
623 * Initialise option states.
624 */
625 if (cfg.passive_telnet) {
626 struct Opt **o;
627
628 for (o = opts; *o; o++)
629 if ((*o)->state == REQUESTED)
630 (*o)->state = INACTIVE;
631 } else {
632 struct Opt **o;
633
634 for (o = opts; *o; o++)
635 if ((*o)->state == REQUESTED)
636 send_opt((*o)->send, (*o)->option);
637 activated = TRUE;
638 }
639
640 /*
641 * Set up SYNCH state.
642 */
643 in_synch = FALSE;
644
645 return NULL;
646 }
647
648 /*
649 * Called to send data down the Telnet connection.
650 */
651 static void telnet_send(char *buf, int len)
652 {
653 char *p;
654 static unsigned char iac[2] = { IAC, IAC };
655 static unsigned char cr[2] = { CR, NUL };
656 static unsigned char nl[2] = { CR, LF };
657
658 if (s == NULL)
659 return;
660
661 p = buf;
662 while (p < buf + len) {
663 char *q = p;
664
665 while (iswritable((unsigned char) *p) && p < buf + len)
666 p++;
667 sk_write(s, q, p - q);
668
669 while (p < buf + len && !iswritable((unsigned char) *p)) {
670 sk_write(s, (unsigned char) *p == IAC ? iac : nl, 2);
671 p++;
672 }
673 }
674 }
675
676 /*
677 * Called to set the size of the window from Telnet's POV.
678 */
679 static void telnet_size(void)
680 {
681 unsigned char b[16];
682 char logbuf[50];
683
684 if (s == NULL || o_naws.state != ACTIVE)
685 return;
686 b[0] = IAC;
687 b[1] = SB;
688 b[2] = TELOPT_NAWS;
689 b[3] = cols >> 8;
690 b[4] = cols & 0xFF;
691 b[5] = rows >> 8;
692 b[6] = rows & 0xFF;
693 b[7] = IAC;
694 b[8] = SE;
695 sk_write(s, b, 9);
696 sprintf(logbuf, "client:\tSB NAWS %d,%d",
697 ((unsigned char) b[3] << 8) + (unsigned char) b[4],
698 ((unsigned char) b[5] << 8) + (unsigned char) b[6]);
699 logevent(logbuf);
700 }
701
702 /*
703 * Send Telnet special codes.
704 */
705 static void telnet_special(Telnet_Special code)
706 {
707 unsigned char b[2];
708
709 if (s == NULL)
710 return;
711
712 b[0] = IAC;
713 switch (code) {
714 case TS_AYT:
715 b[1] = AYT;
716 sk_write(s, b, 2);
717 break;
718 case TS_BRK:
719 b[1] = BREAK;
720 sk_write(s, b, 2);
721 break;
722 case TS_EC:
723 b[1] = EC;
724 sk_write(s, b, 2);
725 break;
726 case TS_EL:
727 b[1] = EL;
728 sk_write(s, b, 2);
729 break;
730 case TS_GA:
731 b[1] = GA;
732 sk_write(s, b, 2);
733 break;
734 case TS_NOP:
735 b[1] = NOP;
736 sk_write(s, b, 2);
737 break;
738 case TS_ABORT:
739 b[1] = ABORT;
740 sk_write(s, b, 2);
741 break;
742 case TS_AO:
743 b[1] = AO;
744 sk_write(s, b, 2);
745 break;
746 case TS_IP:
747 b[1] = IP;
748 sk_write(s, b, 2);
749 break;
750 case TS_SUSP:
751 b[1] = SUSP;
752 sk_write(s, b, 2);
753 break;
754 case TS_EOR:
755 b[1] = EOR;
756 sk_write(s, b, 2);
757 break;
758 case TS_EOF:
759 b[1] = xEOF;
760 sk_write(s, b, 2);
761 break;
762 case TS_SYNCH:
763 b[1] = DM;
764 sk_write(s, b, 1);
765 sk_write_oob(s, b + 1, 1);
766 break;
767 case TS_RECHO:
768 if (o_echo.state == INACTIVE || o_echo.state == REALLY_INACTIVE) {
769 o_echo.state = REQUESTED;
770 send_opt(o_echo.send, o_echo.option);
771 }
772 break;
773 case TS_LECHO:
774 if (o_echo.state == ACTIVE) {
775 o_echo.state = REQUESTED;
776 send_opt(o_echo.nsend, o_echo.option);
777 }
778 break;
779 case TS_PING:
780 if (o_they_sga.state == ACTIVE) {
781 b[1] = NOP;
782 sk_write(s, b, 2);
783 }
784 break;
785 }
786 }
787
788 static Socket telnet_socket(void)
789 {
790 return s;
791 }
792
793 static int telnet_sendok(void)
794 {
795 return 1;
796 }
797
798 static int telnet_ldisc(int option)
799 {
800 if (option == LD_ECHO)
801 return echoing;
802 if (option == LD_EDIT)
803 return editing;
804 return FALSE;
805 }
806
807 Backend telnet_backend = {
808 telnet_init,
809 telnet_send,
810 telnet_size,
811 telnet_special,
812 telnet_socket,
813 telnet_sendok,
814 telnet_ldisc,
815 23
816 };
Local modifications for Simon Tatham's `PuTTY' SSH client and terminal emulator