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pterm.c now relies on backend `exitcode' functions returning <0 when
[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_TN3270E 40 /* TN3270 enhancements */
76 #define TELOPT_XAUTH 41
77 #define TELOPT_CHARSET 42 /* Character set */
78 #define TELOPT_RSP 43 /* Remote serial port */
79 #define TELOPT_COM_PORT_OPTION 44 /* Com port control */
80 #define TELOPT_SLE 45 /* Suppress local echo */
81 #define TELOPT_STARTTLS 46 /* Start TLS */
82 #define TELOPT_KERMIT 47 /* Automatic Kermit file transfer */
83 #define TELOPT_SEND_URL 48
84 #define TELOPT_FORWARD_X 49
85 #define TELOPT_PRAGMA_LOGON 138
86 #define TELOPT_SSPI_LOGON 139
87 #define TELOPT_PRAGMA_HEARTBEAT 140
88 #define TELOPT_EXOPL 255 /* extended-options-list */
89
90 #define TELQUAL_IS 0 /* option is... */
91 #define TELQUAL_SEND 1 /* send option */
92 #define TELQUAL_INFO 2 /* ENVIRON: informational version of IS */
93 #define BSD_VAR 1
94 #define BSD_VALUE 0
95 #define RFC_VAR 0
96 #define RFC_VALUE 1
97
98 #define CR 13
99 #define LF 10
100 #define NUL 0
101
102 #define iswritable(x) \
103 ( (x) != IAC && \
104 (telnet->opt_states[o_we_bin.index] == ACTIVE || (x) != CR))
105
106 static char *telopt(int opt)
107 {
108 #define i(x) if (opt == TELOPT_ ## x) return #x;
109 i(BINARY);
110 i(ECHO);
111 i(RCP);
112 i(SGA);
113 i(NAMS);
114 i(STATUS);
115 i(TM);
116 i(RCTE);
117 i(NAOL);
118 i(NAOP);
119 i(NAOCRD);
120 i(NAOHTS);
121 i(NAOHTD);
122 i(NAOFFD);
123 i(NAOVTS);
124 i(NAOVTD);
125 i(NAOLFD);
126 i(XASCII);
127 i(LOGOUT);
128 i(BM);
129 i(DET);
130 i(SUPDUP);
131 i(SUPDUPOUTPUT);
132 i(SNDLOC);
133 i(TTYPE);
134 i(EOR);
135 i(TUID);
136 i(OUTMRK);
137 i(TTYLOC);
138 i(X3PAD);
139 i(NAWS);
140 i(TSPEED);
141 i(LFLOW);
142 i(LINEMODE);
143 i(XDISPLOC);
144 i(OLD_ENVIRON);
145 i(AUTHENTICATION);
146 i(ENCRYPT);
147 i(NEW_ENVIRON);
148 i(TN3270E);
149 i(XAUTH);
150 i(CHARSET);
151 i(RSP);
152 i(COM_PORT_OPTION);
153 i(SLE);
154 i(STARTTLS);
155 i(KERMIT);
156 i(SEND_URL);
157 i(FORWARD_X);
158 i(PRAGMA_LOGON);
159 i(SSPI_LOGON);
160 i(PRAGMA_HEARTBEAT);
161 i(EXOPL);
162 #undef i
163 return "<unknown>";
164 }
165
166 static void telnet_size(void *handle, int width, int height);
167
168 struct Opt {
169 int send; /* what we initially send */
170 int nsend; /* -ve send if requested to stop it */
171 int ack, nak; /* +ve and -ve acknowledgements */
172 int option; /* the option code */
173 int index; /* index into telnet->opt_states[] */
174 enum {
175 REQUESTED, ACTIVE, INACTIVE, REALLY_INACTIVE
176 } initial_state;
177 };
178
179 enum {
180 OPTINDEX_NAWS,
181 OPTINDEX_TSPEED,
182 OPTINDEX_TTYPE,
183 OPTINDEX_OENV,
184 OPTINDEX_NENV,
185 OPTINDEX_ECHO,
186 OPTINDEX_WE_SGA,
187 OPTINDEX_THEY_SGA,
188 OPTINDEX_WE_BIN,
189 OPTINDEX_THEY_BIN,
190 NUM_OPTS
191 };
192
193 static const struct Opt o_naws =
194 { WILL, WONT, DO, DONT, TELOPT_NAWS, OPTINDEX_NAWS, REQUESTED };
195 static const struct Opt o_tspeed =
196 { WILL, WONT, DO, DONT, TELOPT_TSPEED, OPTINDEX_TSPEED, REQUESTED };
197 static const struct Opt o_ttype =
198 { WILL, WONT, DO, DONT, TELOPT_TTYPE, OPTINDEX_TTYPE, REQUESTED };
199 static const struct Opt o_oenv = { WILL, WONT, DO, DONT, TELOPT_OLD_ENVIRON,
200 OPTINDEX_OENV, INACTIVE
201 };
202 static const struct Opt o_nenv = { WILL, WONT, DO, DONT, TELOPT_NEW_ENVIRON,
203 OPTINDEX_NENV, REQUESTED
204 };
205 static const struct Opt o_echo =
206 { DO, DONT, WILL, WONT, TELOPT_ECHO, OPTINDEX_ECHO, REQUESTED };
207 static const struct Opt o_we_sga =
208 { WILL, WONT, DO, DONT, TELOPT_SGA, OPTINDEX_WE_SGA, REQUESTED };
209 static const struct Opt o_they_sga =
210 { DO, DONT, WILL, WONT, TELOPT_SGA, OPTINDEX_THEY_SGA, REQUESTED };
211 static const struct Opt o_we_bin =
212 { WILL, WONT, DO, DONT, TELOPT_BINARY, OPTINDEX_WE_BIN, INACTIVE };
213 static const struct Opt o_they_bin =
214 { DO, DONT, WILL, WONT, TELOPT_BINARY, OPTINDEX_THEY_BIN, INACTIVE };
215
216 static const struct Opt *const opts[] = {
217 &o_naws, &o_tspeed, &o_ttype, &o_oenv, &o_nenv, &o_echo,
218 &o_we_sga, &o_they_sga, &o_we_bin, &o_they_bin, NULL
219 };
220
221 typedef struct telnet_tag {
222 const struct plug_function_table *fn;
223 /* the above field _must_ be first in the structure */
224
225 Socket s;
226
227 void *frontend;
228 void *ldisc;
229 int term_width, term_height;
230
231 int opt_states[NUM_OPTS];
232
233 int echoing, editing;
234 int activated;
235 int bufsize;
236 int in_synch;
237 int sb_opt, sb_len;
238 unsigned char *sb_buf;
239 int sb_size;
240
241 enum {
242 TOP_LEVEL, SEENIAC, SEENWILL, SEENWONT, SEENDO, SEENDONT,
243 SEENSB, SUBNEGOT, SUBNEG_IAC, SEENCR
244 } state;
245
246 Config cfg;
247 } *Telnet;
248
249 #define TELNET_MAX_BACKLOG 4096
250
251 #define SB_DELTA 1024
252
253 static void c_write1(Telnet telnet, int c)
254 {
255 int backlog;
256 char cc = (char) c;
257 backlog = from_backend(telnet->frontend, 0, &cc, 1);
258 sk_set_frozen(telnet->s, backlog > TELNET_MAX_BACKLOG);
259 }
260
261 static void log_option(Telnet telnet, char *sender, int cmd, int option)
262 {
263 char *buf;
264 /*
265 * The strange-looking "<?""?>" below is there to avoid a
266 * trigraph - a double question mark followed by > maps to a
267 * closing brace character!
268 */
269 buf = dupprintf("%s:\t%s %s", sender,
270 (cmd == WILL ? "WILL" : cmd == WONT ? "WONT" :
271 cmd == DO ? "DO" : cmd == DONT ? "DONT" : "<?""?>"),
272 telopt(option));
273 logevent(telnet->frontend, buf);
274 sfree(buf);
275 }
276
277 static void send_opt(Telnet telnet, int cmd, int option)
278 {
279 unsigned char b[3];
280
281 b[0] = IAC;
282 b[1] = cmd;
283 b[2] = option;
284 telnet->bufsize = sk_write(telnet->s, (char *)b, 3);
285 log_option(telnet, "client", cmd, option);
286 }
287
288 static void deactivate_option(Telnet telnet, const struct Opt *o)
289 {
290 if (telnet->opt_states[o->index] == REQUESTED ||
291 telnet->opt_states[o->index] == ACTIVE)
292 send_opt(telnet, o->nsend, o->option);
293 telnet->opt_states[o->index] = REALLY_INACTIVE;
294 }
295
296 /*
297 * Generate side effects of enabling or disabling an option.
298 */
299 static void option_side_effects(Telnet telnet, const struct Opt *o, int enabled)
300 {
301 if (o->option == TELOPT_ECHO && o->send == DO)
302 telnet->echoing = !enabled;
303 else if (o->option == TELOPT_SGA && o->send == DO)
304 telnet->editing = !enabled;
305 if (telnet->ldisc) /* cause ldisc to notice the change */
306 ldisc_send(telnet->ldisc, NULL, 0, 0);
307
308 /* Ensure we get the minimum options */
309 if (!telnet->activated) {
310 if (telnet->opt_states[o_echo.index] == INACTIVE) {
311 telnet->opt_states[o_echo.index] = REQUESTED;
312 send_opt(telnet, o_echo.send, o_echo.option);
313 }
314 if (telnet->opt_states[o_we_sga.index] == INACTIVE) {
315 telnet->opt_states[o_we_sga.index] = REQUESTED;
316 send_opt(telnet, o_we_sga.send, o_we_sga.option);
317 }
318 if (telnet->opt_states[o_they_sga.index] == INACTIVE) {
319 telnet->opt_states[o_they_sga.index] = REQUESTED;
320 send_opt(telnet, o_they_sga.send, o_they_sga.option);
321 }
322 telnet->activated = TRUE;
323 }
324 }
325
326 static void activate_option(Telnet telnet, const struct Opt *o)
327 {
328 if (o->send == WILL && o->option == TELOPT_NAWS)
329 telnet_size(telnet, telnet->term_width, telnet->term_height);
330 if (o->send == WILL &&
331 (o->option == TELOPT_NEW_ENVIRON ||
332 o->option == TELOPT_OLD_ENVIRON)) {
333 /*
334 * We may only have one kind of ENVIRON going at a time.
335 * This is a hack, but who cares.
336 */
337 deactivate_option(telnet, o->option ==
338 TELOPT_NEW_ENVIRON ? &o_oenv : &o_nenv);
339 }
340 option_side_effects(telnet, o, 1);
341 }
342
343 static void refused_option(Telnet telnet, const struct Opt *o)
344 {
345 if (o->send == WILL && o->option == TELOPT_NEW_ENVIRON &&
346 telnet->opt_states[o_oenv.index] == INACTIVE) {
347 send_opt(telnet, WILL, TELOPT_OLD_ENVIRON);
348 telnet->opt_states[o_oenv.index] = REQUESTED;
349 }
350 option_side_effects(telnet, o, 0);
351 }
352
353 static void proc_rec_opt(Telnet telnet, int cmd, int option)
354 {
355 const struct Opt *const *o;
356
357 log_option(telnet, "server", cmd, option);
358 for (o = opts; *o; o++) {
359 if ((*o)->option == option && (*o)->ack == cmd) {
360 switch (telnet->opt_states[(*o)->index]) {
361 case REQUESTED:
362 telnet->opt_states[(*o)->index] = ACTIVE;
363 activate_option(telnet, *o);
364 break;
365 case ACTIVE:
366 break;
367 case INACTIVE:
368 telnet->opt_states[(*o)->index] = ACTIVE;
369 send_opt(telnet, (*o)->send, option);
370 activate_option(telnet, *o);
371 break;
372 case REALLY_INACTIVE:
373 send_opt(telnet, (*o)->nsend, option);
374 break;
375 }
376 return;
377 } else if ((*o)->option == option && (*o)->nak == cmd) {
378 switch (telnet->opt_states[(*o)->index]) {
379 case REQUESTED:
380 telnet->opt_states[(*o)->index] = INACTIVE;
381 refused_option(telnet, *o);
382 break;
383 case ACTIVE:
384 telnet->opt_states[(*o)->index] = INACTIVE;
385 send_opt(telnet, (*o)->nsend, option);
386 option_side_effects(telnet, *o, 0);
387 break;
388 case INACTIVE:
389 case REALLY_INACTIVE:
390 break;
391 }
392 return;
393 }
394 }
395 /*
396 * If we reach here, the option was one we weren't prepared to
397 * cope with. So send a negative ack.
398 */
399 send_opt(telnet, (cmd == WILL ? DONT : WONT), option);
400 }
401
402 static void process_subneg(Telnet telnet)
403 {
404 unsigned char b[2048], *p, *q;
405 int var, value, n;
406 char *e;
407
408 switch (telnet->sb_opt) {
409 case TELOPT_TSPEED:
410 if (telnet->sb_len == 1 && telnet->sb_buf[0] == TELQUAL_SEND) {
411 char *logbuf;
412 b[0] = IAC;
413 b[1] = SB;
414 b[2] = TELOPT_TSPEED;
415 b[3] = TELQUAL_IS;
416 strcpy((char *)(b + 4), telnet->cfg.termspeed);
417 n = 4 + strlen(telnet->cfg.termspeed);
418 b[n] = IAC;
419 b[n + 1] = SE;
420 telnet->bufsize = sk_write(telnet->s, (char *)b, n + 2);
421 logevent(telnet->frontend, "server:\tSB TSPEED SEND");
422 logbuf = dupprintf("client:\tSB TSPEED IS %s", telnet->cfg.termspeed);
423 logevent(telnet->frontend, logbuf);
424 sfree(logbuf);
425 } else
426 logevent(telnet->frontend, "server:\tSB TSPEED <something weird>");
427 break;
428 case TELOPT_TTYPE:
429 if (telnet->sb_len == 1 && telnet->sb_buf[0] == TELQUAL_SEND) {
430 char *logbuf;
431 b[0] = IAC;
432 b[1] = SB;
433 b[2] = TELOPT_TTYPE;
434 b[3] = TELQUAL_IS;
435 for (n = 0; telnet->cfg.termtype[n]; n++)
436 b[n + 4] = (telnet->cfg.termtype[n] >= 'a'
437 && telnet->cfg.termtype[n] <=
438 'z' ? telnet->cfg.termtype[n] + 'A' -
439 'a' : telnet->cfg.termtype[n]);
440 b[n + 4] = IAC;
441 b[n + 5] = SE;
442 telnet->bufsize = sk_write(telnet->s, (char *)b, n + 6);
443 b[n + 4] = 0;
444 logevent(telnet->frontend, "server:\tSB TTYPE SEND");
445 logbuf = dupprintf("client:\tSB TTYPE IS %s", b + 4);
446 logevent(telnet->frontend, logbuf);
447 sfree(logbuf);
448 } else
449 logevent(telnet->frontend, "server:\tSB TTYPE <something weird>\r\n");
450 break;
451 case TELOPT_OLD_ENVIRON:
452 case TELOPT_NEW_ENVIRON:
453 p = telnet->sb_buf;
454 q = p + telnet->sb_len;
455 if (p < q && *p == TELQUAL_SEND) {
456 char *logbuf;
457 p++;
458 logbuf = dupprintf("server:\tSB %s SEND", telopt(telnet->sb_opt));
459 logevent(telnet->frontend, logbuf);
460 sfree(logbuf);
461 if (telnet->sb_opt == TELOPT_OLD_ENVIRON) {
462 if (telnet->cfg.rfc_environ) {
463 value = RFC_VALUE;
464 var = RFC_VAR;
465 } else {
466 value = BSD_VALUE;
467 var = BSD_VAR;
468 }
469 /*
470 * Try to guess the sense of VAR and VALUE.
471 */
472 while (p < q) {
473 if (*p == RFC_VAR) {
474 value = RFC_VALUE;
475 var = RFC_VAR;
476 } else if (*p == BSD_VAR) {
477 value = BSD_VALUE;
478 var = BSD_VAR;
479 }
480 p++;
481 }
482 } else {
483 /*
484 * With NEW_ENVIRON, the sense of VAR and VALUE
485 * isn't in doubt.
486 */
487 value = RFC_VALUE;
488 var = RFC_VAR;
489 }
490 b[0] = IAC;
491 b[1] = SB;
492 b[2] = telnet->sb_opt;
493 b[3] = TELQUAL_IS;
494 n = 4;
495 e = telnet->cfg.environmt;
496 while (*e) {
497 b[n++] = var;
498 while (*e && *e != '\t')
499 b[n++] = *e++;
500 if (*e == '\t')
501 e++;
502 b[n++] = value;
503 while (*e)
504 b[n++] = *e++;
505 e++;
506 }
507 if (*telnet->cfg.username) {
508 b[n++] = var;
509 b[n++] = 'U';
510 b[n++] = 'S';
511 b[n++] = 'E';
512 b[n++] = 'R';
513 b[n++] = value;
514 e = telnet->cfg.username;
515 while (*e)
516 b[n++] = *e++;
517 }
518 b[n++] = IAC;
519 b[n++] = SE;
520 telnet->bufsize = sk_write(telnet->s, (char *)b, n);
521 logbuf = dupprintf("client:\tSB %s IS %s", telopt(telnet->sb_opt),
522 n == 6 ? "<nothing>" : "<stuff>");
523 logevent(telnet->frontend, logbuf);
524 sfree(logbuf);
525 }
526 break;
527 }
528 }
529
530 static void do_telnet_read(Telnet telnet, char *buf, int len)
531 {
532
533 while (len--) {
534 int c = (unsigned char) *buf++;
535
536 switch (telnet->state) {
537 case TOP_LEVEL:
538 case SEENCR:
539 if (c == NUL && telnet->state == SEENCR)
540 telnet->state = TOP_LEVEL;
541 else if (c == IAC)
542 telnet->state = SEENIAC;
543 else {
544 if (!telnet->in_synch)
545 c_write1(telnet, c);
546
547 #if 1
548 /* I can't get the F***ing winsock to insert the urgent IAC
549 * into the right position! Even with SO_OOBINLINE it gives
550 * it to recv too soon. And of course the DM byte (that
551 * arrives in the same packet!) appears several K later!!
552 *
553 * Oh well, we do get the DM in the right place so I'll
554 * just stop hiding on the next 0xf2 and hope for the best.
555 */
556 else if (c == DM)
557 telnet->in_synch = 0;
558 #endif
559 if (c == CR && telnet->opt_states[o_they_bin.index] != ACTIVE)
560 telnet->state = SEENCR;
561 else
562 telnet->state = TOP_LEVEL;
563 }
564 break;
565 case SEENIAC:
566 if (c == DO)
567 telnet->state = SEENDO;
568 else if (c == DONT)
569 telnet->state = SEENDONT;
570 else if (c == WILL)
571 telnet->state = SEENWILL;
572 else if (c == WONT)
573 telnet->state = SEENWONT;
574 else if (c == SB)
575 telnet->state = SEENSB;
576 else if (c == DM) {
577 telnet->in_synch = 0;
578 telnet->state = TOP_LEVEL;
579 } else {
580 /* ignore everything else; print it if it's IAC */
581 if (c == IAC) {
582 c_write1(telnet, c);
583 }
584 telnet->state = TOP_LEVEL;
585 }
586 break;
587 case SEENWILL:
588 proc_rec_opt(telnet, WILL, c);
589 telnet->state = TOP_LEVEL;
590 break;
591 case SEENWONT:
592 proc_rec_opt(telnet, WONT, c);
593 telnet->state = TOP_LEVEL;
594 break;
595 case SEENDO:
596 proc_rec_opt(telnet, DO, c);
597 telnet->state = TOP_LEVEL;
598 break;
599 case SEENDONT:
600 proc_rec_opt(telnet, DONT, c);
601 telnet->state = TOP_LEVEL;
602 break;
603 case SEENSB:
604 telnet->sb_opt = c;
605 telnet->sb_len = 0;
606 telnet->state = SUBNEGOT;
607 break;
608 case SUBNEGOT:
609 if (c == IAC)
610 telnet->state = SUBNEG_IAC;
611 else {
612 subneg_addchar:
613 if (telnet->sb_len >= telnet->sb_size) {
614 telnet->sb_size += SB_DELTA;
615 telnet->sb_buf = sresize(telnet->sb_buf, telnet->sb_size,
616 unsigned char);
617 }
618 telnet->sb_buf[telnet->sb_len++] = c;
619 telnet->state = SUBNEGOT; /* in case we came here by goto */
620 }
621 break;
622 case SUBNEG_IAC:
623 if (c != SE)
624 goto subneg_addchar; /* yes, it's a hack, I know, but... */
625 else {
626 process_subneg(telnet);
627 telnet->state = TOP_LEVEL;
628 }
629 break;
630 }
631 }
632 }
633
634 static int telnet_closing(Plug plug, char *error_msg, int error_code,
635 int calling_back)
636 {
637 Telnet telnet = (Telnet) plug;
638
639 if (telnet->s) {
640 sk_close(telnet->s);
641 telnet->s = NULL;
642 }
643 if (error_msg) {
644 /* A socket error has occurred. */
645 logevent(telnet->frontend, error_msg);
646 connection_fatal("%s", error_msg);
647 } /* Otherwise, the remote side closed the connection normally. */
648 return 0;
649 }
650
651 static int telnet_receive(Plug plug, int urgent, char *data, int len)
652 {
653 Telnet telnet = (Telnet) plug;
654 if (urgent)
655 telnet->in_synch = TRUE;
656 do_telnet_read(telnet, data, len);
657 return 1;
658 }
659
660 static void telnet_sent(Plug plug, int bufsize)
661 {
662 Telnet telnet = (Telnet) plug;
663 telnet->bufsize = bufsize;
664 }
665
666 /*
667 * Called to set up the Telnet connection.
668 *
669 * Returns an error message, or NULL on success.
670 *
671 * Also places the canonical host name into `realhost'. It must be
672 * freed by the caller.
673 */
674 static char *telnet_init(void *frontend_handle, void **backend_handle,
675 Config *cfg,
676 char *host, int port, char **realhost, int nodelay)
677 {
678 static const struct plug_function_table fn_table = {
679 telnet_closing,
680 telnet_receive,
681 telnet_sent
682 };
683 SockAddr addr;
684 char *err;
685 Telnet telnet;
686
687 telnet = snew(struct telnet_tag);
688 telnet->fn = &fn_table;
689 telnet->cfg = *cfg; /* STRUCTURE COPY */
690 telnet->s = NULL;
691 telnet->echoing = TRUE;
692 telnet->editing = TRUE;
693 telnet->activated = FALSE;
694 telnet->sb_buf = NULL;
695 telnet->sb_size = 0;
696 telnet->frontend = frontend_handle;
697 telnet->term_width = telnet->cfg.width;
698 telnet->term_height = telnet->cfg.height;
699 telnet->state = TOP_LEVEL;
700 *backend_handle = telnet;
701
702 /*
703 * Try to find host.
704 */
705 {
706 char *buf;
707 buf = dupprintf("Looking up host \"%s\"", host);
708 logevent(telnet->frontend, buf);
709 sfree(buf);
710 }
711 addr = name_lookup(host, port, realhost, &telnet->cfg);
712 if ((err = sk_addr_error(addr)) != NULL)
713 return err;
714
715 if (port < 0)
716 port = 23; /* default telnet port */
717
718 /*
719 * Open socket.
720 */
721 {
722 char *buf, addrbuf[100];
723 sk_getaddr(addr, addrbuf, 100);
724 buf = dupprintf("Connecting to %s port %d", addrbuf, port);
725 logevent(telnet->frontend, buf);
726 sfree(buf);
727 }
728 telnet->s = new_connection(addr, *realhost, port, 0, 1,
729 nodelay, (Plug) telnet, &telnet->cfg);
730 if ((err = sk_socket_error(telnet->s)) != NULL)
731 return err;
732
733 sk_addr_free(addr);
734
735 /*
736 * Initialise option states.
737 */
738 if (telnet->cfg.passive_telnet) {
739 const struct Opt *const *o;
740
741 for (o = opts; *o; o++)
742 telnet->opt_states[(*o)->index] = INACTIVE;
743 } else {
744 const struct Opt *const *o;
745
746 for (o = opts; *o; o++) {
747 telnet->opt_states[(*o)->index] = (*o)->initial_state;
748 if (telnet->opt_states[(*o)->index] == REQUESTED)
749 send_opt(telnet, (*o)->send, (*o)->option);
750 }
751 telnet->activated = TRUE;
752 }
753
754 /*
755 * Set up SYNCH state.
756 */
757 telnet->in_synch = FALSE;
758
759 return NULL;
760 }
761
762 static void telnet_free(void *handle)
763 {
764 Telnet telnet = (Telnet) handle;
765
766 sfree(telnet->sb_buf);
767 if (telnet->s)
768 sk_close(telnet->s);
769 sfree(telnet);
770 }
771 /*
772 * Reconfigure the Telnet backend. There's no immediate action
773 * necessary, in this backend: we just save the fresh config for
774 * any subsequent negotiations.
775 */
776 static void telnet_reconfig(void *handle, Config *cfg)
777 {
778 Telnet telnet = (Telnet) handle;
779 telnet->cfg = *cfg; /* STRUCTURE COPY */
780 }
781
782 /*
783 * Called to send data down the Telnet connection.
784 */
785 static int telnet_send(void *handle, char *buf, int len)
786 {
787 Telnet telnet = (Telnet) handle;
788 unsigned char *p, *end;
789 static const unsigned char iac[2] = { IAC, IAC };
790 static const unsigned char cr[2] = { CR, NUL };
791 #if 0
792 static const unsigned char nl[2] = { CR, LF };
793 #endif
794
795 if (telnet->s == NULL)
796 return 0;
797
798 p = (unsigned char *)buf;
799 end = (unsigned char *)(buf + len);
800 while (p < end) {
801 unsigned char *q = p;
802
803 while (p < end && iswritable(*p))
804 p++;
805 telnet->bufsize = sk_write(telnet->s, (char *)q, p - q);
806
807 while (p < end && !iswritable(*p)) {
808 telnet->bufsize =
809 sk_write(telnet->s, (char *)(*p == IAC ? iac : cr), 2);
810 p++;
811 }
812 }
813
814 return telnet->bufsize;
815 }
816
817 /*
818 * Called to query the current socket sendability status.
819 */
820 static int telnet_sendbuffer(void *handle)
821 {
822 Telnet telnet = (Telnet) handle;
823 return telnet->bufsize;
824 }
825
826 /*
827 * Called to set the size of the window from Telnet's POV.
828 */
829 static void telnet_size(void *handle, int width, int height)
830 {
831 Telnet telnet = (Telnet) handle;
832 unsigned char b[24];
833 int n;
834 char *logbuf;
835
836 telnet->term_width = width;
837 telnet->term_height = height;
838
839 if (telnet->s == NULL || telnet->opt_states[o_naws.index] != ACTIVE)
840 return;
841 n = 0;
842 b[n++] = IAC;
843 b[n++] = SB;
844 b[n++] = TELOPT_NAWS;
845 b[n++] = telnet->term_width >> 8;
846 if (b[n-1] == IAC) b[n++] = IAC; /* duplicate any IAC byte occurs */
847 b[n++] = telnet->term_width & 0xFF;
848 if (b[n-1] == IAC) b[n++] = IAC; /* duplicate any IAC byte occurs */
849 b[n++] = telnet->term_height >> 8;
850 if (b[n-1] == IAC) b[n++] = IAC; /* duplicate any IAC byte occurs */
851 b[n++] = telnet->term_height & 0xFF;
852 if (b[n-1] == IAC) b[n++] = IAC; /* duplicate any IAC byte occurs */
853 b[n++] = IAC;
854 b[n++] = SE;
855 telnet->bufsize = sk_write(telnet->s, (char *)b, n);
856 logbuf = dupprintf("client:\tSB NAWS %d,%d",
857 telnet->term_width, telnet->term_height);
858 logevent(telnet->frontend, logbuf);
859 sfree(logbuf);
860 }
861
862 /*
863 * Send Telnet special codes.
864 */
865 static void telnet_special(void *handle, Telnet_Special code)
866 {
867 Telnet telnet = (Telnet) handle;
868 unsigned char b[2];
869
870 if (telnet->s == NULL)
871 return;
872
873 b[0] = IAC;
874 switch (code) {
875 case TS_AYT:
876 b[1] = AYT;
877 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
878 break;
879 case TS_BRK:
880 b[1] = BREAK;
881 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
882 break;
883 case TS_EC:
884 b[1] = EC;
885 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
886 break;
887 case TS_EL:
888 b[1] = EL;
889 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
890 break;
891 case TS_GA:
892 b[1] = GA;
893 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
894 break;
895 case TS_NOP:
896 b[1] = NOP;
897 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
898 break;
899 case TS_ABORT:
900 b[1] = ABORT;
901 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
902 break;
903 case TS_AO:
904 b[1] = AO;
905 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
906 break;
907 case TS_IP:
908 b[1] = IP;
909 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
910 break;
911 case TS_SUSP:
912 b[1] = SUSP;
913 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
914 break;
915 case TS_EOR:
916 b[1] = EOR;
917 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
918 break;
919 case TS_EOF:
920 b[1] = xEOF;
921 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
922 break;
923 case TS_EOL:
924 /* In BINARY mode, CR-LF becomes just CR -
925 * and without the NUL suffix too. */
926 if (telnet->opt_states[o_we_bin.index] == ACTIVE)
927 telnet->bufsize = sk_write(telnet->s, "\r", 1);
928 else
929 telnet->bufsize = sk_write(telnet->s, "\r\n", 2);
930 break;
931 case TS_SYNCH:
932 b[1] = DM;
933 telnet->bufsize = sk_write(telnet->s, (char *)b, 1);
934 telnet->bufsize = sk_write_oob(telnet->s, (char *)(b + 1), 1);
935 break;
936 case TS_RECHO:
937 if (telnet->opt_states[o_echo.index] == INACTIVE ||
938 telnet->opt_states[o_echo.index] == REALLY_INACTIVE) {
939 telnet->opt_states[o_echo.index] = REQUESTED;
940 send_opt(telnet, o_echo.send, o_echo.option);
941 }
942 break;
943 case TS_LECHO:
944 if (telnet->opt_states[o_echo.index] == ACTIVE) {
945 telnet->opt_states[o_echo.index] = REQUESTED;
946 send_opt(telnet, o_echo.nsend, o_echo.option);
947 }
948 break;
949 case TS_PING:
950 if (telnet->opt_states[o_they_sga.index] == ACTIVE) {
951 b[1] = NOP;
952 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
953 }
954 break;
955 }
956 }
957
958 static Socket telnet_socket(void *handle)
959 {
960 Telnet telnet = (Telnet) handle;
961 return telnet->s;
962 }
963
964 static int telnet_sendok(void *handle)
965 {
966 /* Telnet telnet = (Telnet) handle; */
967 return 1;
968 }
969
970 static void telnet_unthrottle(void *handle, int backlog)
971 {
972 Telnet telnet = (Telnet) handle;
973 sk_set_frozen(telnet->s, backlog > TELNET_MAX_BACKLOG);
974 }
975
976 static int telnet_ldisc(void *handle, int option)
977 {
978 Telnet telnet = (Telnet) handle;
979 if (option == LD_ECHO)
980 return telnet->echoing;
981 if (option == LD_EDIT)
982 return telnet->editing;
983 return FALSE;
984 }
985
986 static void telnet_provide_ldisc(void *handle, void *ldisc)
987 {
988 Telnet telnet = (Telnet) handle;
989 telnet->ldisc = ldisc;
990 }
991
992 static void telnet_provide_logctx(void *handle, void *logctx)
993 {
994 /* This is a stub. */
995 }
996
997 static int telnet_exitcode(void *handle)
998 {
999 Telnet telnet = (Telnet) handle;
1000 if (telnet->s != NULL)
1001 return -1; /* still connected */
1002 else
1003 /* Telnet doesn't transmit exit codes back to the client */
1004 return 0;
1005 }
1006
1007 Backend telnet_backend = {
1008 telnet_init,
1009 telnet_free,
1010 telnet_reconfig,
1011 telnet_send,
1012 telnet_sendbuffer,
1013 telnet_size,
1014 telnet_special,
1015 telnet_socket,
1016 telnet_exitcode,
1017 telnet_sendok,
1018 telnet_ldisc,
1019 telnet_provide_ldisc,
1020 telnet_provide_logctx,
1021 telnet_unthrottle,
1022 23
1023 };
Local modifications for Simon Tatham's `PuTTY' SSH client and terminal emulator