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fe6f5cf94507ab8c600c9cab3f01c0071563a832
[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 =
200 { WILL, WONT, DO, DONT, TELOPT_OLD_ENVIRON, OPTINDEX_OENV, INACTIVE };
201 static const struct Opt o_nenv =
202 { WILL, WONT, DO, DONT, TELOPT_NEW_ENVIRON, OPTINDEX_NENV, REQUESTED };
203 static const struct Opt o_echo =
204 { DO, DONT, WILL, WONT, TELOPT_ECHO, OPTINDEX_ECHO, REQUESTED };
205 static const struct Opt o_we_sga =
206 { WILL, WONT, DO, DONT, TELOPT_SGA, OPTINDEX_WE_SGA, REQUESTED };
207 static const struct Opt o_they_sga =
208 { DO, DONT, WILL, WONT, TELOPT_SGA, OPTINDEX_THEY_SGA, REQUESTED };
209 static const struct Opt o_we_bin =
210 { WILL, WONT, DO, DONT, TELOPT_BINARY, OPTINDEX_WE_BIN, INACTIVE };
211 static const struct Opt o_they_bin =
212 { DO, DONT, WILL, WONT, TELOPT_BINARY, OPTINDEX_THEY_BIN, INACTIVE };
213
214 static const struct Opt *const opts[] = {
215 &o_naws, &o_tspeed, &o_ttype, &o_oenv, &o_nenv, &o_echo,
216 &o_we_sga, &o_they_sga, &o_we_bin, &o_they_bin, NULL
217 };
218
219 typedef struct telnet_tag {
220 const struct plug_function_table *fn;
221 /* the above field _must_ be first in the structure */
222
223 Socket s;
224
225 void *frontend;
226 void *ldisc;
227 int term_width, term_height;
228
229 int opt_states[NUM_OPTS];
230
231 int echoing, editing;
232 int activated;
233 int bufsize;
234 int in_synch;
235 int sb_opt, sb_len;
236 unsigned char *sb_buf;
237 int sb_size;
238
239 enum {
240 TOP_LEVEL, SEENIAC, SEENWILL, SEENWONT, SEENDO, SEENDONT,
241 SEENSB, SUBNEGOT, SUBNEG_IAC, SEENCR
242 } state;
243
244 Config cfg;
245
246 Pinger pinger;
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. If the request was positive (WILL or DO), we send
398 * a negative ack to indicate refusal. If the request was
399 * negative (WONT / DONT), we must do nothing.
400 */
401 if (cmd == WILL || cmd == DO)
402 send_opt(telnet, (cmd == WILL ? DONT : WONT), option);
403 }
404
405 static void process_subneg(Telnet telnet)
406 {
407 unsigned char b[2048], *p, *q;
408 int var, value, n;
409 char *e;
410
411 switch (telnet->sb_opt) {
412 case TELOPT_TSPEED:
413 if (telnet->sb_len == 1 && telnet->sb_buf[0] == TELQUAL_SEND) {
414 char *logbuf;
415 b[0] = IAC;
416 b[1] = SB;
417 b[2] = TELOPT_TSPEED;
418 b[3] = TELQUAL_IS;
419 strcpy((char *)(b + 4), telnet->cfg.termspeed);
420 n = 4 + strlen(telnet->cfg.termspeed);
421 b[n] = IAC;
422 b[n + 1] = SE;
423 telnet->bufsize = sk_write(telnet->s, (char *)b, n + 2);
424 logevent(telnet->frontend, "server:\tSB TSPEED SEND");
425 logbuf = dupprintf("client:\tSB TSPEED IS %s", telnet->cfg.termspeed);
426 logevent(telnet->frontend, logbuf);
427 sfree(logbuf);
428 } else
429 logevent(telnet->frontend, "server:\tSB TSPEED <something weird>");
430 break;
431 case TELOPT_TTYPE:
432 if (telnet->sb_len == 1 && telnet->sb_buf[0] == TELQUAL_SEND) {
433 char *logbuf;
434 b[0] = IAC;
435 b[1] = SB;
436 b[2] = TELOPT_TTYPE;
437 b[3] = TELQUAL_IS;
438 for (n = 0; telnet->cfg.termtype[n]; n++)
439 b[n + 4] = (telnet->cfg.termtype[n] >= 'a'
440 && telnet->cfg.termtype[n] <=
441 'z' ? telnet->cfg.termtype[n] + 'A' -
442 'a' : telnet->cfg.termtype[n]);
443 b[n + 4] = IAC;
444 b[n + 5] = SE;
445 telnet->bufsize = sk_write(telnet->s, (char *)b, n + 6);
446 b[n + 4] = 0;
447 logevent(telnet->frontend, "server:\tSB TTYPE SEND");
448 logbuf = dupprintf("client:\tSB TTYPE IS %s", b + 4);
449 logevent(telnet->frontend, logbuf);
450 sfree(logbuf);
451 } else
452 logevent(telnet->frontend, "server:\tSB TTYPE <something weird>\r\n");
453 break;
454 case TELOPT_OLD_ENVIRON:
455 case TELOPT_NEW_ENVIRON:
456 p = telnet->sb_buf;
457 q = p + telnet->sb_len;
458 if (p < q && *p == TELQUAL_SEND) {
459 char *logbuf;
460 p++;
461 logbuf = dupprintf("server:\tSB %s SEND", telopt(telnet->sb_opt));
462 logevent(telnet->frontend, logbuf);
463 sfree(logbuf);
464 if (telnet->sb_opt == TELOPT_OLD_ENVIRON) {
465 if (telnet->cfg.rfc_environ) {
466 value = RFC_VALUE;
467 var = RFC_VAR;
468 } else {
469 value = BSD_VALUE;
470 var = BSD_VAR;
471 }
472 /*
473 * Try to guess the sense of VAR and VALUE.
474 */
475 while (p < q) {
476 if (*p == RFC_VAR) {
477 value = RFC_VALUE;
478 var = RFC_VAR;
479 } else if (*p == BSD_VAR) {
480 value = BSD_VALUE;
481 var = BSD_VAR;
482 }
483 p++;
484 }
485 } else {
486 /*
487 * With NEW_ENVIRON, the sense of VAR and VALUE
488 * isn't in doubt.
489 */
490 value = RFC_VALUE;
491 var = RFC_VAR;
492 }
493 b[0] = IAC;
494 b[1] = SB;
495 b[2] = telnet->sb_opt;
496 b[3] = TELQUAL_IS;
497 n = 4;
498 e = telnet->cfg.environmt;
499 while (*e) {
500 b[n++] = var;
501 while (*e && *e != '\t')
502 b[n++] = *e++;
503 if (*e == '\t')
504 e++;
505 b[n++] = value;
506 while (*e)
507 b[n++] = *e++;
508 e++;
509 }
510 if (*telnet->cfg.username) {
511 b[n++] = var;
512 b[n++] = 'U';
513 b[n++] = 'S';
514 b[n++] = 'E';
515 b[n++] = 'R';
516 b[n++] = value;
517 e = telnet->cfg.username;
518 while (*e)
519 b[n++] = *e++;
520 }
521 b[n++] = IAC;
522 b[n++] = SE;
523 telnet->bufsize = sk_write(telnet->s, (char *)b, n);
524 logbuf = dupprintf("client:\tSB %s IS %s%s%s%s",
525 telopt(telnet->sb_opt),
526 *telnet->cfg.username ? "USER=" : "",
527 telnet->cfg.username,
528 *telnet->cfg.username ? " " : "",
529 n == 6 ? "<nothing>" :
530 (*telnet->cfg.environmt ? "<stuff>" : ""));
531 logevent(telnet->frontend, logbuf);
532 sfree(logbuf);
533 }
534 break;
535 }
536 }
537
538 static void do_telnet_read(Telnet telnet, char *buf, int len)
539 {
540
541 while (len--) {
542 int c = (unsigned char) *buf++;
543
544 switch (telnet->state) {
545 case TOP_LEVEL:
546 case SEENCR:
547 if (c == NUL && telnet->state == SEENCR)
548 telnet->state = TOP_LEVEL;
549 else if (c == IAC)
550 telnet->state = SEENIAC;
551 else {
552 if (!telnet->in_synch)
553 c_write1(telnet, c);
554
555 #if 1
556 /* I can't get the F***ing winsock to insert the urgent IAC
557 * into the right position! Even with SO_OOBINLINE it gives
558 * it to recv too soon. And of course the DM byte (that
559 * arrives in the same packet!) appears several K later!!
560 *
561 * Oh well, we do get the DM in the right place so I'll
562 * just stop hiding on the next 0xf2 and hope for the best.
563 */
564 else if (c == DM)
565 telnet->in_synch = 0;
566 #endif
567 if (c == CR && telnet->opt_states[o_they_bin.index] != ACTIVE)
568 telnet->state = SEENCR;
569 else
570 telnet->state = TOP_LEVEL;
571 }
572 break;
573 case SEENIAC:
574 if (c == DO)
575 telnet->state = SEENDO;
576 else if (c == DONT)
577 telnet->state = SEENDONT;
578 else if (c == WILL)
579 telnet->state = SEENWILL;
580 else if (c == WONT)
581 telnet->state = SEENWONT;
582 else if (c == SB)
583 telnet->state = SEENSB;
584 else if (c == DM) {
585 telnet->in_synch = 0;
586 telnet->state = TOP_LEVEL;
587 } else {
588 /* ignore everything else; print it if it's IAC */
589 if (c == IAC) {
590 c_write1(telnet, c);
591 }
592 telnet->state = TOP_LEVEL;
593 }
594 break;
595 case SEENWILL:
596 proc_rec_opt(telnet, WILL, c);
597 telnet->state = TOP_LEVEL;
598 break;
599 case SEENWONT:
600 proc_rec_opt(telnet, WONT, c);
601 telnet->state = TOP_LEVEL;
602 break;
603 case SEENDO:
604 proc_rec_opt(telnet, DO, c);
605 telnet->state = TOP_LEVEL;
606 break;
607 case SEENDONT:
608 proc_rec_opt(telnet, DONT, c);
609 telnet->state = TOP_LEVEL;
610 break;
611 case SEENSB:
612 telnet->sb_opt = c;
613 telnet->sb_len = 0;
614 telnet->state = SUBNEGOT;
615 break;
616 case SUBNEGOT:
617 if (c == IAC)
618 telnet->state = SUBNEG_IAC;
619 else {
620 subneg_addchar:
621 if (telnet->sb_len >= telnet->sb_size) {
622 telnet->sb_size += SB_DELTA;
623 telnet->sb_buf = sresize(telnet->sb_buf, telnet->sb_size,
624 unsigned char);
625 }
626 telnet->sb_buf[telnet->sb_len++] = c;
627 telnet->state = SUBNEGOT; /* in case we came here by goto */
628 }
629 break;
630 case SUBNEG_IAC:
631 if (c != SE)
632 goto subneg_addchar; /* yes, it's a hack, I know, but... */
633 else {
634 process_subneg(telnet);
635 telnet->state = TOP_LEVEL;
636 }
637 break;
638 }
639 }
640 }
641
642 static void telnet_log(Plug plug, int type, SockAddr addr, int port,
643 const char *error_msg, int error_code)
644 {
645 Telnet telnet = (Telnet) plug;
646 char addrbuf[256], *msg;
647
648 sk_getaddr(addr, addrbuf, lenof(addrbuf));
649
650 if (type == 0)
651 msg = dupprintf("Connecting to %s port %d", addrbuf, port);
652 else
653 msg = dupprintf("Failed to connect to %s: %s", addrbuf, error_msg);
654
655 logevent(telnet->frontend, msg);
656 }
657
658 static int telnet_closing(Plug plug, const char *error_msg, int error_code,
659 int calling_back)
660 {
661 Telnet telnet = (Telnet) plug;
662
663 if (telnet->s) {
664 sk_close(telnet->s);
665 telnet->s = NULL;
666 notify_remote_exit(telnet->frontend);
667 }
668 if (error_msg) {
669 logevent(telnet->frontend, error_msg);
670 connection_fatal(telnet->frontend, "%s", error_msg);
671 }
672 /* Otherwise, the remote side closed the connection normally. */
673 return 0;
674 }
675
676 static int telnet_receive(Plug plug, int urgent, char *data, int len)
677 {
678 Telnet telnet = (Telnet) plug;
679 if (urgent)
680 telnet->in_synch = TRUE;
681 do_telnet_read(telnet, data, len);
682 return 1;
683 }
684
685 static void telnet_sent(Plug plug, int bufsize)
686 {
687 Telnet telnet = (Telnet) plug;
688 telnet->bufsize = bufsize;
689 }
690
691 /*
692 * Called to set up the Telnet connection.
693 *
694 * Returns an error message, or NULL on success.
695 *
696 * Also places the canonical host name into `realhost'. It must be
697 * freed by the caller.
698 */
699 static const char *telnet_init(void *frontend_handle, void **backend_handle,
700 Config *cfg,
701 char *host, int port, char **realhost,
702 int nodelay, int keepalive)
703 {
704 static const struct plug_function_table fn_table = {
705 telnet_log,
706 telnet_closing,
707 telnet_receive,
708 telnet_sent
709 };
710 SockAddr addr;
711 const char *err;
712 Telnet telnet;
713
714 telnet = snew(struct telnet_tag);
715 telnet->fn = &fn_table;
716 telnet->cfg = *cfg; /* STRUCTURE COPY */
717 telnet->s = NULL;
718 telnet->echoing = TRUE;
719 telnet->editing = TRUE;
720 telnet->activated = FALSE;
721 telnet->sb_buf = NULL;
722 telnet->sb_size = 0;
723 telnet->frontend = frontend_handle;
724 telnet->term_width = telnet->cfg.width;
725 telnet->term_height = telnet->cfg.height;
726 telnet->state = TOP_LEVEL;
727 telnet->ldisc = NULL;
728 telnet->pinger = NULL;
729 *backend_handle = telnet;
730
731 /*
732 * Try to find host.
733 */
734 {
735 char *buf;
736 buf = dupprintf("Looking up host \"%s\"%s", host,
737 (cfg->addressfamily == ADDRTYPE_IPV4 ? " (IPv4)" :
738 (cfg->addressfamily == ADDRTYPE_IPV6 ? " (IPv6)" :
739 "")));
740 logevent(telnet->frontend, buf);
741 sfree(buf);
742 }
743 addr = name_lookup(host, port, realhost, &telnet->cfg, cfg->addressfamily);
744 if ((err = sk_addr_error(addr)) != NULL) {
745 sk_addr_free(addr);
746 return err;
747 }
748
749 if (port < 0)
750 port = 23; /* default telnet port */
751
752 /*
753 * Open socket.
754 */
755 telnet->s = new_connection(addr, *realhost, port, 0, 1,
756 nodelay, keepalive, (Plug) telnet, &telnet->cfg);
757 if ((err = sk_socket_error(telnet->s)) != NULL)
758 return err;
759
760 telnet->pinger = pinger_new(&telnet->cfg, &telnet_backend, telnet);
761
762 /*
763 * Initialise option states.
764 */
765 if (telnet->cfg.passive_telnet) {
766 const struct Opt *const *o;
767
768 for (o = opts; *o; o++)
769 telnet->opt_states[(*o)->index] = INACTIVE;
770 } else {
771 const struct Opt *const *o;
772
773 for (o = opts; *o; o++) {
774 telnet->opt_states[(*o)->index] = (*o)->initial_state;
775 if (telnet->opt_states[(*o)->index] == REQUESTED)
776 send_opt(telnet, (*o)->send, (*o)->option);
777 }
778 telnet->activated = TRUE;
779 }
780
781 /*
782 * Set up SYNCH state.
783 */
784 telnet->in_synch = FALSE;
785
786 /*
787 * We can send special commands from the start.
788 */
789 update_specials_menu(telnet->frontend);
790
791 return NULL;
792 }
793
794 static void telnet_free(void *handle)
795 {
796 Telnet telnet = (Telnet) handle;
797
798 sfree(telnet->sb_buf);
799 if (telnet->s)
800 sk_close(telnet->s);
801 if (telnet->pinger)
802 pinger_free(telnet->pinger);
803 sfree(telnet);
804 }
805 /*
806 * Reconfigure the Telnet backend. There's no immediate action
807 * necessary, in this backend: we just save the fresh config for
808 * any subsequent negotiations.
809 */
810 static void telnet_reconfig(void *handle, Config *cfg)
811 {
812 Telnet telnet = (Telnet) handle;
813 pinger_reconfig(telnet->pinger, &telnet->cfg, cfg);
814 telnet->cfg = *cfg; /* STRUCTURE COPY */
815 }
816
817 /*
818 * Called to send data down the Telnet connection.
819 */
820 static int telnet_send(void *handle, char *buf, int len)
821 {
822 Telnet telnet = (Telnet) handle;
823 unsigned char *p, *end;
824 static const unsigned char iac[2] = { IAC, IAC };
825 static const unsigned char cr[2] = { CR, NUL };
826 #if 0
827 static const unsigned char nl[2] = { CR, LF };
828 #endif
829
830 if (telnet->s == NULL)
831 return 0;
832
833 p = (unsigned char *)buf;
834 end = (unsigned char *)(buf + len);
835 while (p < end) {
836 unsigned char *q = p;
837
838 while (p < end && iswritable(*p))
839 p++;
840 telnet->bufsize = sk_write(telnet->s, (char *)q, p - q);
841
842 while (p < end && !iswritable(*p)) {
843 telnet->bufsize =
844 sk_write(telnet->s, (char *)(*p == IAC ? iac : cr), 2);
845 p++;
846 }
847 }
848
849 return telnet->bufsize;
850 }
851
852 /*
853 * Called to query the current socket sendability status.
854 */
855 static int telnet_sendbuffer(void *handle)
856 {
857 Telnet telnet = (Telnet) handle;
858 return telnet->bufsize;
859 }
860
861 /*
862 * Called to set the size of the window from Telnet's POV.
863 */
864 static void telnet_size(void *handle, int width, int height)
865 {
866 Telnet telnet = (Telnet) handle;
867 unsigned char b[24];
868 int n;
869 char *logbuf;
870
871 telnet->term_width = width;
872 telnet->term_height = height;
873
874 if (telnet->s == NULL || telnet->opt_states[o_naws.index] != ACTIVE)
875 return;
876 n = 0;
877 b[n++] = IAC;
878 b[n++] = SB;
879 b[n++] = TELOPT_NAWS;
880 b[n++] = telnet->term_width >> 8;
881 if (b[n-1] == IAC) b[n++] = IAC; /* duplicate any IAC byte occurs */
882 b[n++] = telnet->term_width & 0xFF;
883 if (b[n-1] == IAC) b[n++] = IAC; /* duplicate any IAC byte occurs */
884 b[n++] = telnet->term_height >> 8;
885 if (b[n-1] == IAC) b[n++] = IAC; /* duplicate any IAC byte occurs */
886 b[n++] = telnet->term_height & 0xFF;
887 if (b[n-1] == IAC) b[n++] = IAC; /* duplicate any IAC byte occurs */
888 b[n++] = IAC;
889 b[n++] = SE;
890 telnet->bufsize = sk_write(telnet->s, (char *)b, n);
891 logbuf = dupprintf("client:\tSB NAWS %d,%d",
892 telnet->term_width, telnet->term_height);
893 logevent(telnet->frontend, logbuf);
894 sfree(logbuf);
895 }
896
897 /*
898 * Send Telnet special codes.
899 */
900 static void telnet_special(void *handle, Telnet_Special code)
901 {
902 Telnet telnet = (Telnet) handle;
903 unsigned char b[2];
904
905 if (telnet->s == NULL)
906 return;
907
908 b[0] = IAC;
909 switch (code) {
910 case TS_AYT:
911 b[1] = AYT;
912 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
913 break;
914 case TS_BRK:
915 b[1] = BREAK;
916 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
917 break;
918 case TS_EC:
919 b[1] = EC;
920 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
921 break;
922 case TS_EL:
923 b[1] = EL;
924 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
925 break;
926 case TS_GA:
927 b[1] = GA;
928 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
929 break;
930 case TS_NOP:
931 b[1] = NOP;
932 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
933 break;
934 case TS_ABORT:
935 b[1] = ABORT;
936 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
937 break;
938 case TS_AO:
939 b[1] = AO;
940 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
941 break;
942 case TS_IP:
943 b[1] = IP;
944 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
945 break;
946 case TS_SUSP:
947 b[1] = SUSP;
948 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
949 break;
950 case TS_EOR:
951 b[1] = EOR;
952 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
953 break;
954 case TS_EOF:
955 b[1] = xEOF;
956 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
957 break;
958 case TS_EOL:
959 /* In BINARY mode, CR-LF becomes just CR -
960 * and without the NUL suffix too. */
961 if (telnet->opt_states[o_we_bin.index] == ACTIVE)
962 telnet->bufsize = sk_write(telnet->s, "\r", 1);
963 else
964 telnet->bufsize = sk_write(telnet->s, "\r\n", 2);
965 break;
966 case TS_SYNCH:
967 b[1] = DM;
968 telnet->bufsize = sk_write(telnet->s, (char *)b, 1);
969 telnet->bufsize = sk_write_oob(telnet->s, (char *)(b + 1), 1);
970 break;
971 case TS_RECHO:
972 if (telnet->opt_states[o_echo.index] == INACTIVE ||
973 telnet->opt_states[o_echo.index] == REALLY_INACTIVE) {
974 telnet->opt_states[o_echo.index] = REQUESTED;
975 send_opt(telnet, o_echo.send, o_echo.option);
976 }
977 break;
978 case TS_LECHO:
979 if (telnet->opt_states[o_echo.index] == ACTIVE) {
980 telnet->opt_states[o_echo.index] = REQUESTED;
981 send_opt(telnet, o_echo.nsend, o_echo.option);
982 }
983 break;
984 case TS_PING:
985 if (telnet->opt_states[o_they_sga.index] == ACTIVE) {
986 b[1] = NOP;
987 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
988 }
989 break;
990 default:
991 break; /* never heard of it */
992 }
993 }
994
995 static const struct telnet_special *telnet_get_specials(void *handle)
996 {
997 static const struct telnet_special specials[] = {
998 {"Are You There", TS_AYT},
999 {"Break", TS_BRK},
1000 {"Synch", TS_SYNCH},
1001 {"Erase Character", TS_EC},
1002 {"Erase Line", TS_EL},
1003 {"Go Ahead", TS_GA},
1004 {"No Operation", TS_NOP},
1005 {NULL, TS_SEP},
1006 {"Abort Process", TS_ABORT},
1007 {"Abort Output", TS_AO},
1008 {"Interrupt Process", TS_IP},
1009 {"Suspend Process", TS_SUSP},
1010 {NULL, TS_SEP},
1011 {"End Of Record", TS_EOR},
1012 {"End Of File", TS_EOF},
1013 {NULL, TS_EXITMENU}
1014 };
1015 return specials;
1016 }
1017
1018 static Socket telnet_socket(void *handle)
1019 {
1020 Telnet telnet = (Telnet) handle;
1021 return telnet->s;
1022 }
1023
1024 static int telnet_sendok(void *handle)
1025 {
1026 /* Telnet telnet = (Telnet) handle; */
1027 return 1;
1028 }
1029
1030 static void telnet_unthrottle(void *handle, int backlog)
1031 {
1032 Telnet telnet = (Telnet) handle;
1033 sk_set_frozen(telnet->s, backlog > TELNET_MAX_BACKLOG);
1034 }
1035
1036 static int telnet_ldisc(void *handle, int option)
1037 {
1038 Telnet telnet = (Telnet) handle;
1039 if (option == LD_ECHO)
1040 return telnet->echoing;
1041 if (option == LD_EDIT)
1042 return telnet->editing;
1043 return FALSE;
1044 }
1045
1046 static void telnet_provide_ldisc(void *handle, void *ldisc)
1047 {
1048 Telnet telnet = (Telnet) handle;
1049 telnet->ldisc = ldisc;
1050 }
1051
1052 static void telnet_provide_logctx(void *handle, void *logctx)
1053 {
1054 /* This is a stub. */
1055 }
1056
1057 static int telnet_exitcode(void *handle)
1058 {
1059 Telnet telnet = (Telnet) handle;
1060 if (telnet->s != NULL)
1061 return -1; /* still connected */
1062 else
1063 /* Telnet doesn't transmit exit codes back to the client */
1064 return 0;
1065 }
1066
1067 /*
1068 * cfg_info for Telnet does nothing at all.
1069 */
1070 static int telnet_cfg_info(void *handle)
1071 {
1072 return 0;
1073 }
1074
1075 Backend telnet_backend = {
1076 telnet_init,
1077 telnet_free,
1078 telnet_reconfig,
1079 telnet_send,
1080 telnet_sendbuffer,
1081 telnet_size,
1082 telnet_special,
1083 telnet_get_specials,
1084 telnet_socket,
1085 telnet_exitcode,
1086 telnet_sendok,
1087 telnet_ldisc,
1088 telnet_provide_ldisc,
1089 telnet_provide_logctx,
1090 telnet_unthrottle,
1091 telnet_cfg_info,
1092 23
1093 };
Local modifications for Simon Tatham's `PuTTY' SSH client and terminal emulator