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First crack at an implementation of TELOPT_BINARY, which apparently
[u/mdw/putty] / telnet.c
1 #include <stdio.h>
2 #include <stdlib.h>
3
4 #include "putty.h"
5
6 #ifndef FALSE
7 #define FALSE 0
8 #endif
9 #ifndef TRUE
10 #define TRUE 1
11 #endif
12
13 #define IAC 255 /* interpret as command: */
14 #define DONT 254 /* you are not to use option */
15 #define DO 253 /* please, you use option */
16 #define WONT 252 /* I won't use option */
17 #define WILL 251 /* I will use option */
18 #define SB 250 /* interpret as subnegotiation */
19 #define SE 240 /* end sub negotiation */
20
21 #define GA 249 /* you may reverse the line */
22 #define EL 248 /* erase the current line */
23 #define EC 247 /* erase the current character */
24 #define AYT 246 /* are you there */
25 #define AO 245 /* abort output--but let prog finish */
26 #define IP 244 /* interrupt process--permanently */
27 #define BREAK 243 /* break */
28 #define DM 242 /* data mark--for connect. cleaning */
29 #define NOP 241 /* nop */
30 #define EOR 239 /* end of record (transparent mode) */
31 #define ABORT 238 /* Abort process */
32 #define SUSP 237 /* Suspend process */
33 #define xEOF 236 /* End of file: EOF is already used... */
34
35 #define TELOPT_BINARY 0 /* 8-bit data path */
36 #define TELOPT_ECHO 1 /* echo */
37 #define TELOPT_RCP 2 /* prepare to reconnect */
38 #define TELOPT_SGA 3 /* suppress go ahead */
39 #define TELOPT_NAMS 4 /* approximate message size */
40 #define TELOPT_STATUS 5 /* give status */
41 #define TELOPT_TM 6 /* timing mark */
42 #define TELOPT_RCTE 7 /* remote controlled transmission and echo */
43 #define TELOPT_NAOL 8 /* negotiate about output line width */
44 #define TELOPT_NAOP 9 /* negotiate about output page size */
45 #define TELOPT_NAOCRD 10 /* negotiate about CR disposition */
46 #define TELOPT_NAOHTS 11 /* negotiate about horizontal tabstops */
47 #define TELOPT_NAOHTD 12 /* negotiate about horizontal tab disposition */
48 #define TELOPT_NAOFFD 13 /* negotiate about formfeed disposition */
49 #define TELOPT_NAOVTS 14 /* negotiate about vertical tab stops */
50 #define TELOPT_NAOVTD 15 /* negotiate about vertical tab disposition */
51 #define TELOPT_NAOLFD 16 /* negotiate about output LF disposition */
52 #define TELOPT_XASCII 17 /* extended ascic character set */
53 #define TELOPT_LOGOUT 18 /* force logout */
54 #define TELOPT_BM 19 /* byte macro */
55 #define TELOPT_DET 20 /* data entry terminal */
56 #define TELOPT_SUPDUP 21 /* supdup protocol */
57 #define TELOPT_SUPDUPOUTPUT 22 /* supdup output */
58 #define TELOPT_SNDLOC 23 /* send location */
59 #define TELOPT_TTYPE 24 /* terminal type */
60 #define TELOPT_EOR 25 /* end or record */
61 #define TELOPT_TUID 26 /* TACACS user identification */
62 #define TELOPT_OUTMRK 27 /* output marking */
63 #define TELOPT_TTYLOC 28 /* terminal location number */
64 #define TELOPT_3270REGIME 29 /* 3270 regime */
65 #define TELOPT_X3PAD 30 /* X.3 PAD */
66 #define TELOPT_NAWS 31 /* window size */
67 #define TELOPT_TSPEED 32 /* terminal speed */
68 #define TELOPT_LFLOW 33 /* remote flow control */
69 #define TELOPT_LINEMODE 34 /* Linemode option */
70 #define TELOPT_XDISPLOC 35 /* X Display Location */
71 #define TELOPT_OLD_ENVIRON 36 /* Old - Environment variables */
72 #define TELOPT_AUTHENTICATION 37 /* Authenticate */
73 #define TELOPT_ENCRYPT 38 /* Encryption option */
74 #define TELOPT_NEW_ENVIRON 39 /* New - Environment variables */
75 #define TELOPT_EXOPL 255 /* extended-options-list */
76
77 #define TELQUAL_IS 0 /* option is... */
78 #define TELQUAL_SEND 1 /* send option */
79 #define TELQUAL_INFO 2 /* ENVIRON: informational version of IS */
80 #define BSD_VAR 1
81 #define BSD_VALUE 0
82 #define RFC_VAR 0
83 #define RFC_VALUE 1
84
85 #define CR 13
86 #define LF 10
87 #define NUL 0
88
89 #define iswritable(x) \
90 ( (x) != IAC && \
91 (telnet->opt_states[o_we_bin.index] == ACTIVE || (x) != CR))
92
93 static char *telopt(int opt)
94 {
95 #define i(x) if (opt == TELOPT_ ## x) return #x;
96 i(BINARY);
97 i(ECHO);
98 i(RCP);
99 i(SGA);
100 i(NAMS);
101 i(STATUS);
102 i(TM);
103 i(RCTE);
104 i(NAOL);
105 i(NAOP);
106 i(NAOCRD);
107 i(NAOHTS);
108 i(NAOHTD);
109 i(NAOFFD);
110 i(NAOVTS);
111 i(NAOVTD);
112 i(NAOLFD);
113 i(XASCII);
114 i(LOGOUT);
115 i(BM);
116 i(DET);
117 i(SUPDUP);
118 i(SUPDUPOUTPUT);
119 i(SNDLOC);
120 i(TTYPE);
121 i(EOR);
122 i(TUID);
123 i(OUTMRK);
124 i(TTYLOC);
125 i(X3PAD);
126 i(NAWS);
127 i(TSPEED);
128 i(LFLOW);
129 i(LINEMODE);
130 i(XDISPLOC);
131 i(OLD_ENVIRON);
132 i(AUTHENTICATION);
133 i(ENCRYPT);
134 i(NEW_ENVIRON);
135 i(EXOPL);
136 #undef i
137 return "<unknown>";
138 }
139
140 static void telnet_size(void *handle, int width, int height);
141
142 struct Opt {
143 int send; /* what we initially send */
144 int nsend; /* -ve send if requested to stop it */
145 int ack, nak; /* +ve and -ve acknowledgements */
146 int option; /* the option code */
147 int index; /* index into telnet->opt_states[] */
148 enum {
149 REQUESTED, ACTIVE, INACTIVE, REALLY_INACTIVE
150 } initial_state;
151 };
152
153 enum {
154 OPTINDEX_NAWS,
155 OPTINDEX_TSPEED,
156 OPTINDEX_TTYPE,
157 OPTINDEX_OENV,
158 OPTINDEX_NENV,
159 OPTINDEX_ECHO,
160 OPTINDEX_WE_SGA,
161 OPTINDEX_THEY_SGA,
162 OPTINDEX_WE_BIN,
163 OPTINDEX_THEY_BIN,
164 NUM_OPTS
165 };
166
167 static const struct Opt o_naws =
168 { WILL, WONT, DO, DONT, TELOPT_NAWS, OPTINDEX_NAWS, REQUESTED };
169 static const struct Opt o_tspeed =
170 { WILL, WONT, DO, DONT, TELOPT_TSPEED, OPTINDEX_TSPEED, REQUESTED };
171 static const struct Opt o_ttype =
172 { WILL, WONT, DO, DONT, TELOPT_TTYPE, OPTINDEX_TTYPE, REQUESTED };
173 static const struct Opt o_oenv = { WILL, WONT, DO, DONT, TELOPT_OLD_ENVIRON,
174 OPTINDEX_OENV, INACTIVE
175 };
176 static const struct Opt o_nenv = { WILL, WONT, DO, DONT, TELOPT_NEW_ENVIRON,
177 OPTINDEX_NENV, REQUESTED
178 };
179 static const struct Opt o_echo =
180 { DO, DONT, WILL, WONT, TELOPT_ECHO, OPTINDEX_ECHO, REQUESTED };
181 static const struct Opt o_we_sga =
182 { WILL, WONT, DO, DONT, TELOPT_SGA, OPTINDEX_WE_SGA, REQUESTED };
183 static const struct Opt o_they_sga =
184 { DO, DONT, WILL, WONT, TELOPT_SGA, OPTINDEX_THEY_SGA, REQUESTED };
185 static const struct Opt o_we_bin =
186 { WILL, WONT, DO, DONT, TELOPT_BINARY, OPTINDEX_WE_BIN, INACTIVE };
187 static const struct Opt o_they_bin =
188 { DO, DONT, WILL, WONT, TELOPT_BINARY, OPTINDEX_THEY_BIN, INACTIVE };
189
190 static const struct Opt *const opts[] = {
191 &o_naws, &o_tspeed, &o_ttype, &o_oenv, &o_nenv, &o_echo,
192 &o_we_sga, &o_they_sga, &o_we_bin, &o_they_bin, NULL
193 };
194
195 typedef struct telnet_tag {
196 const struct plug_function_table *fn;
197 /* the above field _must_ be first in the structure */
198
199 Socket s;
200
201 void *frontend;
202 void *ldisc;
203 int term_width, term_height;
204
205 int opt_states[NUM_OPTS];
206
207 int echoing, editing;
208 int activated;
209 int bufsize;
210 int in_synch;
211 int sb_opt, sb_len;
212 char *sb_buf;
213 int sb_size;
214
215 enum {
216 TOP_LEVEL, SEENIAC, SEENWILL, SEENWONT, SEENDO, SEENDONT,
217 SEENSB, SUBNEGOT, SUBNEG_IAC, SEENCR
218 } state;
219
220 } *Telnet;
221
222 #define TELNET_MAX_BACKLOG 4096
223
224 #define SB_DELTA 1024
225
226 static void c_write1(Telnet telnet, int c)
227 {
228 int backlog;
229 char cc = (char) c;
230 backlog = from_backend(telnet->frontend, 0, &cc, 1);
231 sk_set_frozen(telnet->s, backlog > TELNET_MAX_BACKLOG);
232 }
233
234 static void log_option(Telnet telnet, char *sender, int cmd, int option)
235 {
236 char *buf;
237 /*
238 * The strange-looking "<?""?>" below is there to avoid a
239 * trigraph - a double question mark followed by > maps to a
240 * closing brace character!
241 */
242 buf = dupprintf("%s:\t%s %s", sender,
243 (cmd == WILL ? "WILL" : cmd == WONT ? "WONT" :
244 cmd == DO ? "DO" : cmd == DONT ? "DONT" : "<?""?>"),
245 telopt(option));
246 logevent(telnet->frontend, buf);
247 sfree(buf);
248 }
249
250 static void send_opt(Telnet telnet, int cmd, int option)
251 {
252 unsigned char b[3];
253
254 b[0] = IAC;
255 b[1] = cmd;
256 b[2] = option;
257 telnet->bufsize = sk_write(telnet->s, b, 3);
258 log_option(telnet, "client", cmd, option);
259 }
260
261 static void deactivate_option(Telnet telnet, const struct Opt *o)
262 {
263 if (telnet->opt_states[o->index] == REQUESTED ||
264 telnet->opt_states[o->index] == ACTIVE)
265 send_opt(telnet, o->nsend, o->option);
266 telnet->opt_states[o->index] = REALLY_INACTIVE;
267 }
268
269 /*
270 * Generate side effects of enabling or disabling an option.
271 */
272 static void option_side_effects(Telnet telnet, const struct Opt *o, int enabled)
273 {
274 if (o->option == TELOPT_ECHO && o->send == DO)
275 telnet->echoing = !enabled;
276 else if (o->option == TELOPT_SGA && o->send == DO)
277 telnet->editing = !enabled;
278 if (telnet->ldisc) /* cause ldisc to notice the change */
279 ldisc_send(telnet->ldisc, NULL, 0, 0);
280
281 /* Ensure we get the minimum options */
282 if (!telnet->activated) {
283 if (telnet->opt_states[o_echo.index] == INACTIVE) {
284 telnet->opt_states[o_echo.index] = REQUESTED;
285 send_opt(telnet, o_echo.send, o_echo.option);
286 }
287 if (telnet->opt_states[o_we_sga.index] == INACTIVE) {
288 telnet->opt_states[o_we_sga.index] = REQUESTED;
289 send_opt(telnet, o_we_sga.send, o_we_sga.option);
290 }
291 if (telnet->opt_states[o_they_sga.index] == INACTIVE) {
292 telnet->opt_states[o_they_sga.index] = REQUESTED;
293 send_opt(telnet, o_they_sga.send, o_they_sga.option);
294 }
295 telnet->activated = TRUE;
296 }
297 }
298
299 static void activate_option(Telnet telnet, const struct Opt *o)
300 {
301 if (o->send == WILL && o->option == TELOPT_NAWS)
302 telnet_size(telnet, telnet->term_width, telnet->term_height);
303 if (o->send == WILL &&
304 (o->option == TELOPT_NEW_ENVIRON ||
305 o->option == TELOPT_OLD_ENVIRON)) {
306 /*
307 * We may only have one kind of ENVIRON going at a time.
308 * This is a hack, but who cares.
309 */
310 deactivate_option(telnet, o->option ==
311 TELOPT_NEW_ENVIRON ? &o_oenv : &o_nenv);
312 }
313 option_side_effects(telnet, o, 1);
314 }
315
316 static void refused_option(Telnet telnet, const struct Opt *o)
317 {
318 if (o->send == WILL && o->option == TELOPT_NEW_ENVIRON &&
319 telnet->opt_states[o_oenv.index] == INACTIVE) {
320 send_opt(telnet, WILL, TELOPT_OLD_ENVIRON);
321 telnet->opt_states[o_oenv.index] = REQUESTED;
322 }
323 option_side_effects(telnet, o, 0);
324 }
325
326 static void proc_rec_opt(Telnet telnet, int cmd, int option)
327 {
328 const struct Opt *const *o;
329
330 log_option(telnet, "server", cmd, option);
331 for (o = opts; *o; o++) {
332 if ((*o)->option == option && (*o)->ack == cmd) {
333 switch (telnet->opt_states[(*o)->index]) {
334 case REQUESTED:
335 telnet->opt_states[(*o)->index] = ACTIVE;
336 activate_option(telnet, *o);
337 break;
338 case ACTIVE:
339 break;
340 case INACTIVE:
341 telnet->opt_states[(*o)->index] = ACTIVE;
342 send_opt(telnet, (*o)->send, option);
343 activate_option(telnet, *o);
344 break;
345 case REALLY_INACTIVE:
346 send_opt(telnet, (*o)->nsend, option);
347 break;
348 }
349 return;
350 } else if ((*o)->option == option && (*o)->nak == cmd) {
351 switch (telnet->opt_states[(*o)->index]) {
352 case REQUESTED:
353 telnet->opt_states[(*o)->index] = INACTIVE;
354 refused_option(telnet, *o);
355 break;
356 case ACTIVE:
357 telnet->opt_states[(*o)->index] = INACTIVE;
358 send_opt(telnet, (*o)->nsend, option);
359 option_side_effects(telnet, *o, 0);
360 break;
361 case INACTIVE:
362 case REALLY_INACTIVE:
363 break;
364 }
365 return;
366 }
367 }
368 /*
369 * If we reach here, the option was one we weren't prepared to
370 * cope with. So send a negative ack.
371 */
372 send_opt(telnet, (cmd == WILL ? DONT : WONT), option);
373 }
374
375 static void process_subneg(Telnet telnet)
376 {
377 unsigned char b[2048], *p, *q;
378 int var, value, n;
379 char *e;
380
381 switch (telnet->sb_opt) {
382 case TELOPT_TSPEED:
383 if (telnet->sb_len == 1 && telnet->sb_buf[0] == TELQUAL_SEND) {
384 char *logbuf;
385 b[0] = IAC;
386 b[1] = SB;
387 b[2] = TELOPT_TSPEED;
388 b[3] = TELQUAL_IS;
389 strcpy(b + 4, cfg.termspeed);
390 n = 4 + strlen(cfg.termspeed);
391 b[n] = IAC;
392 b[n + 1] = SE;
393 telnet->bufsize = sk_write(telnet->s, b, n + 2);
394 logevent(telnet->frontend, "server:\tSB TSPEED SEND");
395 logbuf = dupprintf("client:\tSB TSPEED IS %s", cfg.termspeed);
396 logevent(telnet->frontend, logbuf);
397 sfree(logbuf);
398 } else
399 logevent(telnet->frontend, "server:\tSB TSPEED <something weird>");
400 break;
401 case TELOPT_TTYPE:
402 if (telnet->sb_len == 1 && telnet->sb_buf[0] == TELQUAL_SEND) {
403 char *logbuf;
404 b[0] = IAC;
405 b[1] = SB;
406 b[2] = TELOPT_TTYPE;
407 b[3] = TELQUAL_IS;
408 for (n = 0; cfg.termtype[n]; n++)
409 b[n + 4] = (cfg.termtype[n] >= 'a'
410 && cfg.termtype[n] <=
411 'z' ? cfg.termtype[n] + 'A' -
412 'a' : cfg.termtype[n]);
413 b[n + 4] = IAC;
414 b[n + 5] = SE;
415 telnet->bufsize = sk_write(telnet->s, b, n + 6);
416 b[n + 4] = 0;
417 logevent(telnet->frontend, "server:\tSB TTYPE SEND");
418 logbuf = dupprintf("client:\tSB TTYPE IS %s", b + 4);
419 logevent(telnet->frontend, logbuf);
420 sfree(logbuf);
421 } else
422 logevent(telnet->frontend, "server:\tSB TTYPE <something weird>\r\n");
423 break;
424 case TELOPT_OLD_ENVIRON:
425 case TELOPT_NEW_ENVIRON:
426 p = telnet->sb_buf;
427 q = p + telnet->sb_len;
428 if (p < q && *p == TELQUAL_SEND) {
429 char *logbuf;
430 p++;
431 logbuf = dupprintf("server:\tSB %s SEND", telopt(telnet->sb_opt));
432 logevent(telnet->frontend, logbuf);
433 sfree(logbuf);
434 if (telnet->sb_opt == TELOPT_OLD_ENVIRON) {
435 if (cfg.rfc_environ) {
436 value = RFC_VALUE;
437 var = RFC_VAR;
438 } else {
439 value = BSD_VALUE;
440 var = BSD_VAR;
441 }
442 /*
443 * Try to guess the sense of VAR and VALUE.
444 */
445 while (p < q) {
446 if (*p == RFC_VAR) {
447 value = RFC_VALUE;
448 var = RFC_VAR;
449 } else if (*p == BSD_VAR) {
450 value = BSD_VALUE;
451 var = BSD_VAR;
452 }
453 p++;
454 }
455 } else {
456 /*
457 * With NEW_ENVIRON, the sense of VAR and VALUE
458 * isn't in doubt.
459 */
460 value = RFC_VALUE;
461 var = RFC_VAR;
462 }
463 b[0] = IAC;
464 b[1] = SB;
465 b[2] = telnet->sb_opt;
466 b[3] = TELQUAL_IS;
467 n = 4;
468 e = cfg.environmt;
469 while (*e) {
470 b[n++] = var;
471 while (*e && *e != '\t')
472 b[n++] = *e++;
473 if (*e == '\t')
474 e++;
475 b[n++] = value;
476 while (*e)
477 b[n++] = *e++;
478 e++;
479 }
480 if (*cfg.username) {
481 b[n++] = var;
482 b[n++] = 'U';
483 b[n++] = 'S';
484 b[n++] = 'E';
485 b[n++] = 'R';
486 b[n++] = value;
487 e = cfg.username;
488 while (*e)
489 b[n++] = *e++;
490 }
491 b[n++] = IAC;
492 b[n++] = SE;
493 telnet->bufsize = sk_write(telnet->s, b, n);
494 logbuf = dupprintf("client:\tSB %s IS %s", telopt(telnet->sb_opt),
495 n == 6 ? "<nothing>" : "<stuff>");
496 logevent(telnet->frontend, logbuf);
497 sfree(logbuf);
498 }
499 break;
500 }
501 }
502
503 static void do_telnet_read(Telnet telnet, char *buf, int len)
504 {
505
506 while (len--) {
507 int c = (unsigned char) *buf++;
508
509 switch (telnet->state) {
510 case TOP_LEVEL:
511 case SEENCR:
512 if (c == NUL && telnet->state == SEENCR)
513 telnet->state = TOP_LEVEL;
514 else if (c == IAC)
515 telnet->state = SEENIAC;
516 else {
517 if (!telnet->in_synch)
518 c_write1(telnet, c);
519
520 #if 1
521 /* I can't get the F***ing winsock to insert the urgent IAC
522 * into the right position! Even with SO_OOBINLINE it gives
523 * it to recv too soon. And of course the DM byte (that
524 * arrives in the same packet!) appears several K later!!
525 *
526 * Oh well, we do get the DM in the right place so I'll
527 * just stop hiding on the next 0xf2 and hope for the best.
528 */
529 else if (c == DM)
530 telnet->in_synch = 0;
531 #endif
532 if (c == CR && telnet->opt_states[o_they_bin.index] != ACTIVE)
533 telnet->state = SEENCR;
534 else
535 telnet->state = TOP_LEVEL;
536 }
537 break;
538 case SEENIAC:
539 if (c == DO)
540 telnet->state = SEENDO;
541 else if (c == DONT)
542 telnet->state = SEENDONT;
543 else if (c == WILL)
544 telnet->state = SEENWILL;
545 else if (c == WONT)
546 telnet->state = SEENWONT;
547 else if (c == SB)
548 telnet->state = SEENSB;
549 else if (c == DM) {
550 telnet->in_synch = 0;
551 telnet->state = TOP_LEVEL;
552 } else {
553 /* ignore everything else; print it if it's IAC */
554 if (c == IAC) {
555 c_write1(telnet, c);
556 }
557 telnet->state = TOP_LEVEL;
558 }
559 break;
560 case SEENWILL:
561 proc_rec_opt(telnet, WILL, c);
562 telnet->state = TOP_LEVEL;
563 break;
564 case SEENWONT:
565 proc_rec_opt(telnet, WONT, c);
566 telnet->state = TOP_LEVEL;
567 break;
568 case SEENDO:
569 proc_rec_opt(telnet, DO, c);
570 telnet->state = TOP_LEVEL;
571 break;
572 case SEENDONT:
573 proc_rec_opt(telnet, DONT, c);
574 telnet->state = TOP_LEVEL;
575 break;
576 case SEENSB:
577 telnet->sb_opt = c;
578 telnet->sb_len = 0;
579 telnet->state = SUBNEGOT;
580 break;
581 case SUBNEGOT:
582 if (c == IAC)
583 telnet->state = SUBNEG_IAC;
584 else {
585 subneg_addchar:
586 if (telnet->sb_len >= telnet->sb_size) {
587 char *newbuf;
588 telnet->sb_size += SB_DELTA;
589 newbuf = (telnet->sb_buf ?
590 srealloc(telnet->sb_buf, telnet->sb_size) :
591 smalloc(telnet->sb_size));
592 if (newbuf)
593 telnet->sb_buf = newbuf;
594 else
595 telnet->sb_size -= SB_DELTA;
596 }
597 if (telnet->sb_len < telnet->sb_size)
598 telnet->sb_buf[telnet->sb_len++] = c;
599 telnet->state = SUBNEGOT; /* in case we came here by goto */
600 }
601 break;
602 case SUBNEG_IAC:
603 if (c != SE)
604 goto subneg_addchar; /* yes, it's a hack, I know, but... */
605 else {
606 process_subneg(telnet);
607 telnet->state = TOP_LEVEL;
608 }
609 break;
610 }
611 }
612 }
613
614 static int telnet_closing(Plug plug, char *error_msg, int error_code,
615 int calling_back)
616 {
617 Telnet telnet = (Telnet) plug;
618
619 if (telnet->s) {
620 sk_close(telnet->s);
621 telnet->s = NULL;
622 }
623 if (error_msg) {
624 /* A socket error has occurred. */
625 logevent(telnet->frontend, error_msg);
626 connection_fatal("%s", error_msg);
627 } /* Otherwise, the remote side closed the connection normally. */
628 return 0;
629 }
630
631 static int telnet_receive(Plug plug, int urgent, char *data, int len)
632 {
633 Telnet telnet = (Telnet) plug;
634 if (urgent)
635 telnet->in_synch = TRUE;
636 do_telnet_read(telnet, data, len);
637 return 1;
638 }
639
640 static void telnet_sent(Plug plug, int bufsize)
641 {
642 Telnet telnet = (Telnet) plug;
643 telnet->bufsize = bufsize;
644 }
645
646 /*
647 * Called to set up the Telnet connection.
648 *
649 * Returns an error message, or NULL on success.
650 *
651 * Also places the canonical host name into `realhost'. It must be
652 * freed by the caller.
653 */
654 static char *telnet_init(void *frontend_handle, void **backend_handle,
655 char *host, int port, char **realhost, int nodelay)
656 {
657 static const struct plug_function_table fn_table = {
658 telnet_closing,
659 telnet_receive,
660 telnet_sent
661 };
662 SockAddr addr;
663 char *err;
664 Telnet telnet;
665
666 telnet = smalloc(sizeof(*telnet));
667 telnet->fn = &fn_table;
668 telnet->s = NULL;
669 telnet->echoing = TRUE;
670 telnet->editing = TRUE;
671 telnet->activated = FALSE;
672 telnet->sb_buf = NULL;
673 telnet->sb_size = 0;
674 telnet->frontend = frontend_handle;
675 telnet->term_width = cfg.width;
676 telnet->term_height = cfg.height;
677 telnet->state = TOP_LEVEL;
678 *backend_handle = telnet;
679
680 /*
681 * Try to find host.
682 */
683 {
684 char *buf;
685 buf = dupprintf("Looking up host \"%s\"", host);
686 logevent(telnet->frontend, buf);
687 sfree(buf);
688 }
689 addr = name_lookup(host, port, realhost);
690 if ((err = sk_addr_error(addr)))
691 return err;
692
693 if (port < 0)
694 port = 23; /* default telnet port */
695
696 /*
697 * Open socket.
698 */
699 {
700 char *buf, addrbuf[100];
701 sk_getaddr(addr, addrbuf, 100);
702 buf = dupprintf("Connecting to %s port %d", addrbuf, port);
703 logevent(telnet->frontend, buf);
704 sfree(buf);
705 }
706 telnet->s = new_connection(addr, *realhost, port, 0, 1,
707 nodelay, (Plug) telnet);
708 if ((err = sk_socket_error(telnet->s)))
709 return err;
710
711 sk_addr_free(addr);
712
713 /*
714 * Initialise option states.
715 */
716 if (cfg.passive_telnet) {
717 const struct Opt *const *o;
718
719 for (o = opts; *o; o++)
720 telnet->opt_states[(*o)->index] = INACTIVE;
721 } else {
722 const struct Opt *const *o;
723
724 for (o = opts; *o; o++) {
725 telnet->opt_states[(*o)->index] = (*o)->initial_state;
726 if (telnet->opt_states[(*o)->index] == REQUESTED)
727 send_opt(telnet, (*o)->send, (*o)->option);
728 }
729 telnet->activated = TRUE;
730 }
731
732 /*
733 * Set up SYNCH state.
734 */
735 telnet->in_synch = FALSE;
736
737 return NULL;
738 }
739
740 /*
741 * Called to send data down the Telnet connection.
742 */
743 static int telnet_send(void *handle, char *buf, int len)
744 {
745 Telnet telnet = (Telnet) handle;
746 char *p;
747 static unsigned char iac[2] = { IAC, IAC };
748 static unsigned char cr[2] = { CR, NUL };
749 #if 0
750 static unsigned char nl[2] = { CR, LF };
751 #endif
752
753 if (telnet->s == NULL)
754 return 0;
755
756 p = buf;
757 while (p < buf + len) {
758 char *q = p;
759
760 while (p < buf + len && iswritable((unsigned char) *p))
761 p++;
762 telnet->bufsize = sk_write(telnet->s, q, p - q);
763
764 while (p < buf + len && !iswritable((unsigned char) *p)) {
765 telnet->bufsize =
766 sk_write(telnet->s, (unsigned char) *p == IAC ? iac : cr, 2);
767 p++;
768 }
769 }
770
771 return telnet->bufsize;
772 }
773
774 /*
775 * Called to query the current socket sendability status.
776 */
777 static int telnet_sendbuffer(void *handle)
778 {
779 Telnet telnet = (Telnet) handle;
780 return telnet->bufsize;
781 }
782
783 /*
784 * Called to set the size of the window from Telnet's POV.
785 */
786 static void telnet_size(void *handle, int width, int height)
787 {
788 Telnet telnet = (Telnet) handle;
789 unsigned char b[16];
790 char *logbuf;
791
792 telnet->term_width = width;
793 telnet->term_height = height;
794
795 if (telnet->s == NULL || telnet->opt_states[o_naws.index] != ACTIVE)
796 return;
797 b[0] = IAC;
798 b[1] = SB;
799 b[2] = TELOPT_NAWS;
800 b[3] = telnet->term_width >> 8;
801 b[4] = telnet->term_width & 0xFF;
802 b[5] = telnet->term_height >> 8;
803 b[6] = telnet->term_height & 0xFF;
804 b[7] = IAC;
805 b[8] = SE;
806 telnet->bufsize = sk_write(telnet->s, b, 9);
807 logbuf = dupprintf("client:\tSB NAWS %d,%d",
808 ((unsigned char) b[3] << 8) + (unsigned char) b[4],
809 ((unsigned char) b[5] << 8) + (unsigned char) b[6]);
810 logevent(telnet->frontend, logbuf);
811 sfree(logbuf);
812 }
813
814 /*
815 * Send Telnet special codes.
816 */
817 static void telnet_special(void *handle, Telnet_Special code)
818 {
819 Telnet telnet = (Telnet) handle;
820 unsigned char b[2];
821
822 if (telnet->s == NULL)
823 return;
824
825 b[0] = IAC;
826 switch (code) {
827 case TS_AYT:
828 b[1] = AYT;
829 telnet->bufsize = sk_write(telnet->s, b, 2);
830 break;
831 case TS_BRK:
832 b[1] = BREAK;
833 telnet->bufsize = sk_write(telnet->s, b, 2);
834 break;
835 case TS_EC:
836 b[1] = EC;
837 telnet->bufsize = sk_write(telnet->s, b, 2);
838 break;
839 case TS_EL:
840 b[1] = EL;
841 telnet->bufsize = sk_write(telnet->s, b, 2);
842 break;
843 case TS_GA:
844 b[1] = GA;
845 telnet->bufsize = sk_write(telnet->s, b, 2);
846 break;
847 case TS_NOP:
848 b[1] = NOP;
849 telnet->bufsize = sk_write(telnet->s, b, 2);
850 break;
851 case TS_ABORT:
852 b[1] = ABORT;
853 telnet->bufsize = sk_write(telnet->s, b, 2);
854 break;
855 case TS_AO:
856 b[1] = AO;
857 telnet->bufsize = sk_write(telnet->s, b, 2);
858 break;
859 case TS_IP:
860 b[1] = IP;
861 telnet->bufsize = sk_write(telnet->s, b, 2);
862 break;
863 case TS_SUSP:
864 b[1] = SUSP;
865 telnet->bufsize = sk_write(telnet->s, b, 2);
866 break;
867 case TS_EOR:
868 b[1] = EOR;
869 telnet->bufsize = sk_write(telnet->s, b, 2);
870 break;
871 case TS_EOF:
872 b[1] = xEOF;
873 telnet->bufsize = sk_write(telnet->s, b, 2);
874 break;
875 case TS_EOL:
876 /* In BINARY mode, CR-LF becomes just CR. */
877 if (telnet->opt_states[o_we_bin.index] == ACTIVE)
878 telnet->bufsize = sk_write(telnet->s, "\r", 2);
879 else
880 telnet->bufsize = sk_write(telnet->s, "\r\n", 2);
881 break;
882 case TS_SYNCH:
883 b[1] = DM;
884 telnet->bufsize = sk_write(telnet->s, b, 1);
885 telnet->bufsize = sk_write_oob(telnet->s, b + 1, 1);
886 break;
887 case TS_RECHO:
888 if (telnet->opt_states[o_echo.index] == INACTIVE ||
889 telnet->opt_states[o_echo.index] == REALLY_INACTIVE) {
890 telnet->opt_states[o_echo.index] = REQUESTED;
891 send_opt(telnet, o_echo.send, o_echo.option);
892 }
893 break;
894 case TS_LECHO:
895 if (telnet->opt_states[o_echo.index] == ACTIVE) {
896 telnet->opt_states[o_echo.index] = REQUESTED;
897 send_opt(telnet, o_echo.nsend, o_echo.option);
898 }
899 break;
900 case TS_PING:
901 if (telnet->opt_states[o_they_sga.index] == ACTIVE) {
902 b[1] = NOP;
903 telnet->bufsize = sk_write(telnet->s, b, 2);
904 }
905 break;
906 }
907 }
908
909 static Socket telnet_socket(void *handle)
910 {
911 Telnet telnet = (Telnet) handle;
912 return telnet->s;
913 }
914
915 static int telnet_sendok(void *handle)
916 {
917 /* Telnet telnet = (Telnet) handle; */
918 return 1;
919 }
920
921 static void telnet_unthrottle(void *handle, int backlog)
922 {
923 Telnet telnet = (Telnet) handle;
924 sk_set_frozen(telnet->s, backlog > TELNET_MAX_BACKLOG);
925 }
926
927 static int telnet_ldisc(void *handle, int option)
928 {
929 Telnet telnet = (Telnet) handle;
930 if (option == LD_ECHO)
931 return telnet->echoing;
932 if (option == LD_EDIT)
933 return telnet->editing;
934 return FALSE;
935 }
936
937 static void telnet_provide_ldisc(void *handle, void *ldisc)
938 {
939 Telnet telnet = (Telnet) handle;
940 telnet->ldisc = ldisc;
941 }
942
943 static void telnet_provide_logctx(void *handle, void *logctx)
944 {
945 /* This is a stub. */
946 }
947
948 static int telnet_exitcode(void *handle)
949 {
950 /* Telnet telnet = (Telnet) handle; */
951 /* Telnet doesn't transmit exit codes back to the client */
952 return 0;
953 }
954
955 Backend telnet_backend = {
956 telnet_init,
957 telnet_send,
958 telnet_sendbuffer,
959 telnet_size,
960 telnet_special,
961 telnet_socket,
962 telnet_exitcode,
963 telnet_sendok,
964 telnet_ldisc,
965 telnet_provide_ldisc,
966 telnet_provide_logctx,
967 telnet_unthrottle,
968 23
969 };
Local modifications for Simon Tatham's `PuTTY' SSH client and terminal emulator