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Sprinkle some header comments in various files in an attempt to explain what
[u/mdw/putty] / telnet.c
1 /*
2 * Telnet backend.
3 */
4
5 #include <stdio.h>
6 #include <stdlib.h>
7
8 #include "putty.h"
9
10 #ifndef FALSE
11 #define FALSE 0
12 #endif
13 #ifndef TRUE
14 #define TRUE 1
15 #endif
16
17 #define IAC 255 /* interpret as command: */
18 #define DONT 254 /* you are not to use option */
19 #define DO 253 /* please, you use option */
20 #define WONT 252 /* I won't use option */
21 #define WILL 251 /* I will use option */
22 #define SB 250 /* interpret as subnegotiation */
23 #define SE 240 /* end sub negotiation */
24
25 #define GA 249 /* you may reverse the line */
26 #define EL 248 /* erase the current line */
27 #define EC 247 /* erase the current character */
28 #define AYT 246 /* are you there */
29 #define AO 245 /* abort output--but let prog finish */
30 #define IP 244 /* interrupt process--permanently */
31 #define BREAK 243 /* break */
32 #define DM 242 /* data mark--for connect. cleaning */
33 #define NOP 241 /* nop */
34 #define EOR 239 /* end of record (transparent mode) */
35 #define ABORT 238 /* Abort process */
36 #define SUSP 237 /* Suspend process */
37 #define xEOF 236 /* End of file: EOF is already used... */
38
39 #define TELOPT_BINARY 0 /* 8-bit data path */
40 #define TELOPT_ECHO 1 /* echo */
41 #define TELOPT_RCP 2 /* prepare to reconnect */
42 #define TELOPT_SGA 3 /* suppress go ahead */
43 #define TELOPT_NAMS 4 /* approximate message size */
44 #define TELOPT_STATUS 5 /* give status */
45 #define TELOPT_TM 6 /* timing mark */
46 #define TELOPT_RCTE 7 /* remote controlled transmission and echo */
47 #define TELOPT_NAOL 8 /* negotiate about output line width */
48 #define TELOPT_NAOP 9 /* negotiate about output page size */
49 #define TELOPT_NAOCRD 10 /* negotiate about CR disposition */
50 #define TELOPT_NAOHTS 11 /* negotiate about horizontal tabstops */
51 #define TELOPT_NAOHTD 12 /* negotiate about horizontal tab disposition */
52 #define TELOPT_NAOFFD 13 /* negotiate about formfeed disposition */
53 #define TELOPT_NAOVTS 14 /* negotiate about vertical tab stops */
54 #define TELOPT_NAOVTD 15 /* negotiate about vertical tab disposition */
55 #define TELOPT_NAOLFD 16 /* negotiate about output LF disposition */
56 #define TELOPT_XASCII 17 /* extended ascic character set */
57 #define TELOPT_LOGOUT 18 /* force logout */
58 #define TELOPT_BM 19 /* byte macro */
59 #define TELOPT_DET 20 /* data entry terminal */
60 #define TELOPT_SUPDUP 21 /* supdup protocol */
61 #define TELOPT_SUPDUPOUTPUT 22 /* supdup output */
62 #define TELOPT_SNDLOC 23 /* send location */
63 #define TELOPT_TTYPE 24 /* terminal type */
64 #define TELOPT_EOR 25 /* end or record */
65 #define TELOPT_TUID 26 /* TACACS user identification */
66 #define TELOPT_OUTMRK 27 /* output marking */
67 #define TELOPT_TTYLOC 28 /* terminal location number */
68 #define TELOPT_3270REGIME 29 /* 3270 regime */
69 #define TELOPT_X3PAD 30 /* X.3 PAD */
70 #define TELOPT_NAWS 31 /* window size */
71 #define TELOPT_TSPEED 32 /* terminal speed */
72 #define TELOPT_LFLOW 33 /* remote flow control */
73 #define TELOPT_LINEMODE 34 /* Linemode option */
74 #define TELOPT_XDISPLOC 35 /* X Display Location */
75 #define TELOPT_OLD_ENVIRON 36 /* Old - Environment variables */
76 #define TELOPT_AUTHENTICATION 37 /* Authenticate */
77 #define TELOPT_ENCRYPT 38 /* Encryption option */
78 #define TELOPT_NEW_ENVIRON 39 /* New - Environment variables */
79 #define TELOPT_TN3270E 40 /* TN3270 enhancements */
80 #define TELOPT_XAUTH 41
81 #define TELOPT_CHARSET 42 /* Character set */
82 #define TELOPT_RSP 43 /* Remote serial port */
83 #define TELOPT_COM_PORT_OPTION 44 /* Com port control */
84 #define TELOPT_SLE 45 /* Suppress local echo */
85 #define TELOPT_STARTTLS 46 /* Start TLS */
86 #define TELOPT_KERMIT 47 /* Automatic Kermit file transfer */
87 #define TELOPT_SEND_URL 48
88 #define TELOPT_FORWARD_X 49
89 #define TELOPT_PRAGMA_LOGON 138
90 #define TELOPT_SSPI_LOGON 139
91 #define TELOPT_PRAGMA_HEARTBEAT 140
92 #define TELOPT_EXOPL 255 /* extended-options-list */
93
94 #define TELQUAL_IS 0 /* option is... */
95 #define TELQUAL_SEND 1 /* send option */
96 #define TELQUAL_INFO 2 /* ENVIRON: informational version of IS */
97 #define BSD_VAR 1
98 #define BSD_VALUE 0
99 #define RFC_VAR 0
100 #define RFC_VALUE 1
101
102 #define CR 13
103 #define LF 10
104 #define NUL 0
105
106 #define iswritable(x) \
107 ( (x) != IAC && \
108 (telnet->opt_states[o_we_bin.index] == ACTIVE || (x) != CR))
109
110 static char *telopt(int opt)
111 {
112 #define i(x) if (opt == TELOPT_ ## x) return #x;
113 i(BINARY);
114 i(ECHO);
115 i(RCP);
116 i(SGA);
117 i(NAMS);
118 i(STATUS);
119 i(TM);
120 i(RCTE);
121 i(NAOL);
122 i(NAOP);
123 i(NAOCRD);
124 i(NAOHTS);
125 i(NAOHTD);
126 i(NAOFFD);
127 i(NAOVTS);
128 i(NAOVTD);
129 i(NAOLFD);
130 i(XASCII);
131 i(LOGOUT);
132 i(BM);
133 i(DET);
134 i(SUPDUP);
135 i(SUPDUPOUTPUT);
136 i(SNDLOC);
137 i(TTYPE);
138 i(EOR);
139 i(TUID);
140 i(OUTMRK);
141 i(TTYLOC);
142 i(X3PAD);
143 i(NAWS);
144 i(TSPEED);
145 i(LFLOW);
146 i(LINEMODE);
147 i(XDISPLOC);
148 i(OLD_ENVIRON);
149 i(AUTHENTICATION);
150 i(ENCRYPT);
151 i(NEW_ENVIRON);
152 i(TN3270E);
153 i(XAUTH);
154 i(CHARSET);
155 i(RSP);
156 i(COM_PORT_OPTION);
157 i(SLE);
158 i(STARTTLS);
159 i(KERMIT);
160 i(SEND_URL);
161 i(FORWARD_X);
162 i(PRAGMA_LOGON);
163 i(SSPI_LOGON);
164 i(PRAGMA_HEARTBEAT);
165 i(EXOPL);
166 #undef i
167 return "<unknown>";
168 }
169
170 static void telnet_size(void *handle, int width, int height);
171
172 struct Opt {
173 int send; /* what we initially send */
174 int nsend; /* -ve send if requested to stop it */
175 int ack, nak; /* +ve and -ve acknowledgements */
176 int option; /* the option code */
177 int index; /* index into telnet->opt_states[] */
178 enum {
179 REQUESTED, ACTIVE, INACTIVE, REALLY_INACTIVE
180 } initial_state;
181 };
182
183 enum {
184 OPTINDEX_NAWS,
185 OPTINDEX_TSPEED,
186 OPTINDEX_TTYPE,
187 OPTINDEX_OENV,
188 OPTINDEX_NENV,
189 OPTINDEX_ECHO,
190 OPTINDEX_WE_SGA,
191 OPTINDEX_THEY_SGA,
192 OPTINDEX_WE_BIN,
193 OPTINDEX_THEY_BIN,
194 NUM_OPTS
195 };
196
197 static const struct Opt o_naws =
198 { WILL, WONT, DO, DONT, TELOPT_NAWS, OPTINDEX_NAWS, REQUESTED };
199 static const struct Opt o_tspeed =
200 { WILL, WONT, DO, DONT, TELOPT_TSPEED, OPTINDEX_TSPEED, REQUESTED };
201 static const struct Opt o_ttype =
202 { WILL, WONT, DO, DONT, TELOPT_TTYPE, OPTINDEX_TTYPE, REQUESTED };
203 static const struct Opt o_oenv =
204 { WILL, WONT, DO, DONT, TELOPT_OLD_ENVIRON, OPTINDEX_OENV, INACTIVE };
205 static const struct Opt o_nenv =
206 { WILL, WONT, DO, DONT, TELOPT_NEW_ENVIRON, OPTINDEX_NENV, REQUESTED };
207 static const struct Opt o_echo =
208 { DO, DONT, WILL, WONT, TELOPT_ECHO, OPTINDEX_ECHO, REQUESTED };
209 static const struct Opt o_we_sga =
210 { WILL, WONT, DO, DONT, TELOPT_SGA, OPTINDEX_WE_SGA, REQUESTED };
211 static const struct Opt o_they_sga =
212 { DO, DONT, WILL, WONT, TELOPT_SGA, OPTINDEX_THEY_SGA, REQUESTED };
213 static const struct Opt o_we_bin =
214 { WILL, WONT, DO, DONT, TELOPT_BINARY, OPTINDEX_WE_BIN, INACTIVE };
215 static const struct Opt o_they_bin =
216 { DO, DONT, WILL, WONT, TELOPT_BINARY, OPTINDEX_THEY_BIN, INACTIVE };
217
218 static const struct Opt *const opts[] = {
219 &o_naws, &o_tspeed, &o_ttype, &o_oenv, &o_nenv, &o_echo,
220 &o_we_sga, &o_they_sga, &o_we_bin, &o_they_bin, NULL
221 };
222
223 typedef struct telnet_tag {
224 const struct plug_function_table *fn;
225 /* the above field _must_ be first in the structure */
226
227 Socket s;
228
229 void *frontend;
230 void *ldisc;
231 int term_width, term_height;
232
233 int opt_states[NUM_OPTS];
234
235 int echoing, editing;
236 int activated;
237 int bufsize;
238 int in_synch;
239 int sb_opt, sb_len;
240 unsigned char *sb_buf;
241 int sb_size;
242
243 enum {
244 TOP_LEVEL, SEENIAC, SEENWILL, SEENWONT, SEENDO, SEENDONT,
245 SEENSB, SUBNEGOT, SUBNEG_IAC, SEENCR
246 } state;
247
248 Config cfg;
249
250 Pinger pinger;
251 } *Telnet;
252
253 #define TELNET_MAX_BACKLOG 4096
254
255 #define SB_DELTA 1024
256
257 static void c_write1(Telnet telnet, int c)
258 {
259 int backlog;
260 char cc = (char) c;
261 backlog = from_backend(telnet->frontend, 0, &cc, 1);
262 sk_set_frozen(telnet->s, backlog > TELNET_MAX_BACKLOG);
263 }
264
265 static void log_option(Telnet telnet, char *sender, int cmd, int option)
266 {
267 char *buf;
268 /*
269 * The strange-looking "<?""?>" below is there to avoid a
270 * trigraph - a double question mark followed by > maps to a
271 * closing brace character!
272 */
273 buf = dupprintf("%s:\t%s %s", sender,
274 (cmd == WILL ? "WILL" : cmd == WONT ? "WONT" :
275 cmd == DO ? "DO" : cmd == DONT ? "DONT" : "<?""?>"),
276 telopt(option));
277 logevent(telnet->frontend, buf);
278 sfree(buf);
279 }
280
281 static void send_opt(Telnet telnet, int cmd, int option)
282 {
283 unsigned char b[3];
284
285 b[0] = IAC;
286 b[1] = cmd;
287 b[2] = option;
288 telnet->bufsize = sk_write(telnet->s, (char *)b, 3);
289 log_option(telnet, "client", cmd, option);
290 }
291
292 static void deactivate_option(Telnet telnet, const struct Opt *o)
293 {
294 if (telnet->opt_states[o->index] == REQUESTED ||
295 telnet->opt_states[o->index] == ACTIVE)
296 send_opt(telnet, o->nsend, o->option);
297 telnet->opt_states[o->index] = REALLY_INACTIVE;
298 }
299
300 /*
301 * Generate side effects of enabling or disabling an option.
302 */
303 static void option_side_effects(Telnet telnet, const struct Opt *o, int enabled)
304 {
305 if (o->option == TELOPT_ECHO && o->send == DO)
306 telnet->echoing = !enabled;
307 else if (o->option == TELOPT_SGA && o->send == DO)
308 telnet->editing = !enabled;
309 if (telnet->ldisc) /* cause ldisc to notice the change */
310 ldisc_send(telnet->ldisc, NULL, 0, 0);
311
312 /* Ensure we get the minimum options */
313 if (!telnet->activated) {
314 if (telnet->opt_states[o_echo.index] == INACTIVE) {
315 telnet->opt_states[o_echo.index] = REQUESTED;
316 send_opt(telnet, o_echo.send, o_echo.option);
317 }
318 if (telnet->opt_states[o_we_sga.index] == INACTIVE) {
319 telnet->opt_states[o_we_sga.index] = REQUESTED;
320 send_opt(telnet, o_we_sga.send, o_we_sga.option);
321 }
322 if (telnet->opt_states[o_they_sga.index] == INACTIVE) {
323 telnet->opt_states[o_they_sga.index] = REQUESTED;
324 send_opt(telnet, o_they_sga.send, o_they_sga.option);
325 }
326 telnet->activated = TRUE;
327 }
328 }
329
330 static void activate_option(Telnet telnet, const struct Opt *o)
331 {
332 if (o->send == WILL && o->option == TELOPT_NAWS)
333 telnet_size(telnet, telnet->term_width, telnet->term_height);
334 if (o->send == WILL &&
335 (o->option == TELOPT_NEW_ENVIRON ||
336 o->option == TELOPT_OLD_ENVIRON)) {
337 /*
338 * We may only have one kind of ENVIRON going at a time.
339 * This is a hack, but who cares.
340 */
341 deactivate_option(telnet, o->option ==
342 TELOPT_NEW_ENVIRON ? &o_oenv : &o_nenv);
343 }
344 option_side_effects(telnet, o, 1);
345 }
346
347 static void refused_option(Telnet telnet, const struct Opt *o)
348 {
349 if (o->send == WILL && o->option == TELOPT_NEW_ENVIRON &&
350 telnet->opt_states[o_oenv.index] == INACTIVE) {
351 send_opt(telnet, WILL, TELOPT_OLD_ENVIRON);
352 telnet->opt_states[o_oenv.index] = REQUESTED;
353 }
354 option_side_effects(telnet, o, 0);
355 }
356
357 static void proc_rec_opt(Telnet telnet, int cmd, int option)
358 {
359 const struct Opt *const *o;
360
361 log_option(telnet, "server", cmd, option);
362 for (o = opts; *o; o++) {
363 if ((*o)->option == option && (*o)->ack == cmd) {
364 switch (telnet->opt_states[(*o)->index]) {
365 case REQUESTED:
366 telnet->opt_states[(*o)->index] = ACTIVE;
367 activate_option(telnet, *o);
368 break;
369 case ACTIVE:
370 break;
371 case INACTIVE:
372 telnet->opt_states[(*o)->index] = ACTIVE;
373 send_opt(telnet, (*o)->send, option);
374 activate_option(telnet, *o);
375 break;
376 case REALLY_INACTIVE:
377 send_opt(telnet, (*o)->nsend, option);
378 break;
379 }
380 return;
381 } else if ((*o)->option == option && (*o)->nak == cmd) {
382 switch (telnet->opt_states[(*o)->index]) {
383 case REQUESTED:
384 telnet->opt_states[(*o)->index] = INACTIVE;
385 refused_option(telnet, *o);
386 break;
387 case ACTIVE:
388 telnet->opt_states[(*o)->index] = INACTIVE;
389 send_opt(telnet, (*o)->nsend, option);
390 option_side_effects(telnet, *o, 0);
391 break;
392 case INACTIVE:
393 case REALLY_INACTIVE:
394 break;
395 }
396 return;
397 }
398 }
399 /*
400 * If we reach here, the option was one we weren't prepared to
401 * cope with. If the request was positive (WILL or DO), we send
402 * a negative ack to indicate refusal. If the request was
403 * negative (WONT / DONT), we must do nothing.
404 */
405 if (cmd == WILL || cmd == DO)
406 send_opt(telnet, (cmd == WILL ? DONT : WONT), option);
407 }
408
409 static void process_subneg(Telnet telnet)
410 {
411 unsigned char b[2048], *p, *q;
412 int var, value, n;
413 char *e;
414
415 switch (telnet->sb_opt) {
416 case TELOPT_TSPEED:
417 if (telnet->sb_len == 1 && telnet->sb_buf[0] == TELQUAL_SEND) {
418 char *logbuf;
419 b[0] = IAC;
420 b[1] = SB;
421 b[2] = TELOPT_TSPEED;
422 b[3] = TELQUAL_IS;
423 strcpy((char *)(b + 4), telnet->cfg.termspeed);
424 n = 4 + strlen(telnet->cfg.termspeed);
425 b[n] = IAC;
426 b[n + 1] = SE;
427 telnet->bufsize = sk_write(telnet->s, (char *)b, n + 2);
428 logevent(telnet->frontend, "server:\tSB TSPEED SEND");
429 logbuf = dupprintf("client:\tSB TSPEED IS %s", telnet->cfg.termspeed);
430 logevent(telnet->frontend, logbuf);
431 sfree(logbuf);
432 } else
433 logevent(telnet->frontend, "server:\tSB TSPEED <something weird>");
434 break;
435 case TELOPT_TTYPE:
436 if (telnet->sb_len == 1 && telnet->sb_buf[0] == TELQUAL_SEND) {
437 char *logbuf;
438 b[0] = IAC;
439 b[1] = SB;
440 b[2] = TELOPT_TTYPE;
441 b[3] = TELQUAL_IS;
442 for (n = 0; telnet->cfg.termtype[n]; n++)
443 b[n + 4] = (telnet->cfg.termtype[n] >= 'a'
444 && telnet->cfg.termtype[n] <=
445 'z' ? telnet->cfg.termtype[n] + 'A' -
446 'a' : telnet->cfg.termtype[n]);
447 b[n + 4] = IAC;
448 b[n + 5] = SE;
449 telnet->bufsize = sk_write(telnet->s, (char *)b, n + 6);
450 b[n + 4] = 0;
451 logevent(telnet->frontend, "server:\tSB TTYPE SEND");
452 logbuf = dupprintf("client:\tSB TTYPE IS %s", b + 4);
453 logevent(telnet->frontend, logbuf);
454 sfree(logbuf);
455 } else
456 logevent(telnet->frontend, "server:\tSB TTYPE <something weird>\r\n");
457 break;
458 case TELOPT_OLD_ENVIRON:
459 case TELOPT_NEW_ENVIRON:
460 p = telnet->sb_buf;
461 q = p + telnet->sb_len;
462 if (p < q && *p == TELQUAL_SEND) {
463 char *logbuf;
464 p++;
465 logbuf = dupprintf("server:\tSB %s SEND", telopt(telnet->sb_opt));
466 logevent(telnet->frontend, logbuf);
467 sfree(logbuf);
468 if (telnet->sb_opt == TELOPT_OLD_ENVIRON) {
469 if (telnet->cfg.rfc_environ) {
470 value = RFC_VALUE;
471 var = RFC_VAR;
472 } else {
473 value = BSD_VALUE;
474 var = BSD_VAR;
475 }
476 /*
477 * Try to guess the sense of VAR and VALUE.
478 */
479 while (p < q) {
480 if (*p == RFC_VAR) {
481 value = RFC_VALUE;
482 var = RFC_VAR;
483 } else if (*p == BSD_VAR) {
484 value = BSD_VALUE;
485 var = BSD_VAR;
486 }
487 p++;
488 }
489 } else {
490 /*
491 * With NEW_ENVIRON, the sense of VAR and VALUE
492 * isn't in doubt.
493 */
494 value = RFC_VALUE;
495 var = RFC_VAR;
496 }
497 b[0] = IAC;
498 b[1] = SB;
499 b[2] = telnet->sb_opt;
500 b[3] = TELQUAL_IS;
501 n = 4;
502 e = telnet->cfg.environmt;
503 while (*e) {
504 b[n++] = var;
505 while (*e && *e != '\t')
506 b[n++] = *e++;
507 if (*e == '\t')
508 e++;
509 b[n++] = value;
510 while (*e)
511 b[n++] = *e++;
512 e++;
513 }
514 if (*telnet->cfg.username) {
515 b[n++] = var;
516 b[n++] = 'U';
517 b[n++] = 'S';
518 b[n++] = 'E';
519 b[n++] = 'R';
520 b[n++] = value;
521 e = telnet->cfg.username;
522 while (*e)
523 b[n++] = *e++;
524 }
525 b[n++] = IAC;
526 b[n++] = SE;
527 telnet->bufsize = sk_write(telnet->s, (char *)b, n);
528 logbuf = dupprintf("client:\tSB %s IS %s%s%s%s",
529 telopt(telnet->sb_opt),
530 *telnet->cfg.username ? "USER=" : "",
531 telnet->cfg.username,
532 *telnet->cfg.username ? " " : "",
533 n == 6 ? "<nothing>" :
534 (*telnet->cfg.environmt ? "<stuff>" : ""));
535 logevent(telnet->frontend, logbuf);
536 sfree(logbuf);
537 }
538 break;
539 }
540 }
541
542 static void do_telnet_read(Telnet telnet, char *buf, int len)
543 {
544
545 while (len--) {
546 int c = (unsigned char) *buf++;
547
548 switch (telnet->state) {
549 case TOP_LEVEL:
550 case SEENCR:
551 if (c == NUL && telnet->state == SEENCR)
552 telnet->state = TOP_LEVEL;
553 else if (c == IAC)
554 telnet->state = SEENIAC;
555 else {
556 if (!telnet->in_synch)
557 c_write1(telnet, c);
558
559 #if 1
560 /* I can't get the F***ing winsock to insert the urgent IAC
561 * into the right position! Even with SO_OOBINLINE it gives
562 * it to recv too soon. And of course the DM byte (that
563 * arrives in the same packet!) appears several K later!!
564 *
565 * Oh well, we do get the DM in the right place so I'll
566 * just stop hiding on the next 0xf2 and hope for the best.
567 */
568 else if (c == DM)
569 telnet->in_synch = 0;
570 #endif
571 if (c == CR && telnet->opt_states[o_they_bin.index] != ACTIVE)
572 telnet->state = SEENCR;
573 else
574 telnet->state = TOP_LEVEL;
575 }
576 break;
577 case SEENIAC:
578 if (c == DO)
579 telnet->state = SEENDO;
580 else if (c == DONT)
581 telnet->state = SEENDONT;
582 else if (c == WILL)
583 telnet->state = SEENWILL;
584 else if (c == WONT)
585 telnet->state = SEENWONT;
586 else if (c == SB)
587 telnet->state = SEENSB;
588 else if (c == DM) {
589 telnet->in_synch = 0;
590 telnet->state = TOP_LEVEL;
591 } else {
592 /* ignore everything else; print it if it's IAC */
593 if (c == IAC) {
594 c_write1(telnet, c);
595 }
596 telnet->state = TOP_LEVEL;
597 }
598 break;
599 case SEENWILL:
600 proc_rec_opt(telnet, WILL, c);
601 telnet->state = TOP_LEVEL;
602 break;
603 case SEENWONT:
604 proc_rec_opt(telnet, WONT, c);
605 telnet->state = TOP_LEVEL;
606 break;
607 case SEENDO:
608 proc_rec_opt(telnet, DO, c);
609 telnet->state = TOP_LEVEL;
610 break;
611 case SEENDONT:
612 proc_rec_opt(telnet, DONT, c);
613 telnet->state = TOP_LEVEL;
614 break;
615 case SEENSB:
616 telnet->sb_opt = c;
617 telnet->sb_len = 0;
618 telnet->state = SUBNEGOT;
619 break;
620 case SUBNEGOT:
621 if (c == IAC)
622 telnet->state = SUBNEG_IAC;
623 else {
624 subneg_addchar:
625 if (telnet->sb_len >= telnet->sb_size) {
626 telnet->sb_size += SB_DELTA;
627 telnet->sb_buf = sresize(telnet->sb_buf, telnet->sb_size,
628 unsigned char);
629 }
630 telnet->sb_buf[telnet->sb_len++] = c;
631 telnet->state = SUBNEGOT; /* in case we came here by goto */
632 }
633 break;
634 case SUBNEG_IAC:
635 if (c != SE)
636 goto subneg_addchar; /* yes, it's a hack, I know, but... */
637 else {
638 process_subneg(telnet);
639 telnet->state = TOP_LEVEL;
640 }
641 break;
642 }
643 }
644 }
645
646 static void telnet_log(Plug plug, int type, SockAddr addr, int port,
647 const char *error_msg, int error_code)
648 {
649 Telnet telnet = (Telnet) plug;
650 char addrbuf[256], *msg;
651
652 sk_getaddr(addr, addrbuf, lenof(addrbuf));
653
654 if (type == 0)
655 msg = dupprintf("Connecting to %s port %d", addrbuf, port);
656 else
657 msg = dupprintf("Failed to connect to %s: %s", addrbuf, error_msg);
658
659 logevent(telnet->frontend, msg);
660 }
661
662 static int telnet_closing(Plug plug, const char *error_msg, int error_code,
663 int calling_back)
664 {
665 Telnet telnet = (Telnet) plug;
666
667 if (telnet->s) {
668 sk_close(telnet->s);
669 telnet->s = NULL;
670 notify_remote_exit(telnet->frontend);
671 }
672 if (error_msg) {
673 logevent(telnet->frontend, error_msg);
674 connection_fatal(telnet->frontend, "%s", error_msg);
675 }
676 /* Otherwise, the remote side closed the connection normally. */
677 return 0;
678 }
679
680 static int telnet_receive(Plug plug, int urgent, char *data, int len)
681 {
682 Telnet telnet = (Telnet) plug;
683 if (urgent)
684 telnet->in_synch = TRUE;
685 do_telnet_read(telnet, data, len);
686 return 1;
687 }
688
689 static void telnet_sent(Plug plug, int bufsize)
690 {
691 Telnet telnet = (Telnet) plug;
692 telnet->bufsize = bufsize;
693 }
694
695 /*
696 * Called to set up the Telnet connection.
697 *
698 * Returns an error message, or NULL on success.
699 *
700 * Also places the canonical host name into `realhost'. It must be
701 * freed by the caller.
702 */
703 static const char *telnet_init(void *frontend_handle, void **backend_handle,
704 Config *cfg,
705 char *host, int port, char **realhost,
706 int nodelay, int keepalive)
707 {
708 static const struct plug_function_table fn_table = {
709 telnet_log,
710 telnet_closing,
711 telnet_receive,
712 telnet_sent
713 };
714 SockAddr addr;
715 const char *err;
716 Telnet telnet;
717
718 telnet = snew(struct telnet_tag);
719 telnet->fn = &fn_table;
720 telnet->cfg = *cfg; /* STRUCTURE COPY */
721 telnet->s = NULL;
722 telnet->echoing = TRUE;
723 telnet->editing = TRUE;
724 telnet->activated = FALSE;
725 telnet->sb_buf = NULL;
726 telnet->sb_size = 0;
727 telnet->frontend = frontend_handle;
728 telnet->term_width = telnet->cfg.width;
729 telnet->term_height = telnet->cfg.height;
730 telnet->state = TOP_LEVEL;
731 telnet->ldisc = NULL;
732 telnet->pinger = NULL;
733 *backend_handle = telnet;
734
735 /*
736 * Try to find host.
737 */
738 {
739 char *buf;
740 buf = dupprintf("Looking up host \"%s\"%s", host,
741 (cfg->addressfamily == ADDRTYPE_IPV4 ? " (IPv4)" :
742 (cfg->addressfamily == ADDRTYPE_IPV6 ? " (IPv6)" :
743 "")));
744 logevent(telnet->frontend, buf);
745 sfree(buf);
746 }
747 addr = name_lookup(host, port, realhost, &telnet->cfg, cfg->addressfamily);
748 if ((err = sk_addr_error(addr)) != NULL) {
749 sk_addr_free(addr);
750 return err;
751 }
752
753 if (port < 0)
754 port = 23; /* default telnet port */
755
756 /*
757 * Open socket.
758 */
759 telnet->s = new_connection(addr, *realhost, port, 0, 1,
760 nodelay, keepalive, (Plug) telnet, &telnet->cfg);
761 if ((err = sk_socket_error(telnet->s)) != NULL)
762 return err;
763
764 telnet->pinger = pinger_new(&telnet->cfg, &telnet_backend, telnet);
765
766 /*
767 * Initialise option states.
768 */
769 if (telnet->cfg.passive_telnet) {
770 const struct Opt *const *o;
771
772 for (o = opts; *o; o++)
773 telnet->opt_states[(*o)->index] = INACTIVE;
774 } else {
775 const struct Opt *const *o;
776
777 for (o = opts; *o; o++) {
778 telnet->opt_states[(*o)->index] = (*o)->initial_state;
779 if (telnet->opt_states[(*o)->index] == REQUESTED)
780 send_opt(telnet, (*o)->send, (*o)->option);
781 }
782 telnet->activated = TRUE;
783 }
784
785 /*
786 * Set up SYNCH state.
787 */
788 telnet->in_synch = FALSE;
789
790 /*
791 * We can send special commands from the start.
792 */
793 update_specials_menu(telnet->frontend);
794
795 return NULL;
796 }
797
798 static void telnet_free(void *handle)
799 {
800 Telnet telnet = (Telnet) handle;
801
802 sfree(telnet->sb_buf);
803 if (telnet->s)
804 sk_close(telnet->s);
805 if (telnet->pinger)
806 pinger_free(telnet->pinger);
807 sfree(telnet);
808 }
809 /*
810 * Reconfigure the Telnet backend. There's no immediate action
811 * necessary, in this backend: we just save the fresh config for
812 * any subsequent negotiations.
813 */
814 static void telnet_reconfig(void *handle, Config *cfg)
815 {
816 Telnet telnet = (Telnet) handle;
817 pinger_reconfig(telnet->pinger, &telnet->cfg, cfg);
818 telnet->cfg = *cfg; /* STRUCTURE COPY */
819 }
820
821 /*
822 * Called to send data down the Telnet connection.
823 */
824 static int telnet_send(void *handle, char *buf, int len)
825 {
826 Telnet telnet = (Telnet) handle;
827 unsigned char *p, *end;
828 static const unsigned char iac[2] = { IAC, IAC };
829 static const unsigned char cr[2] = { CR, NUL };
830 #if 0
831 static const unsigned char nl[2] = { CR, LF };
832 #endif
833
834 if (telnet->s == NULL)
835 return 0;
836
837 p = (unsigned char *)buf;
838 end = (unsigned char *)(buf + len);
839 while (p < end) {
840 unsigned char *q = p;
841
842 while (p < end && iswritable(*p))
843 p++;
844 telnet->bufsize = sk_write(telnet->s, (char *)q, p - q);
845
846 while (p < end && !iswritable(*p)) {
847 telnet->bufsize =
848 sk_write(telnet->s, (char *)(*p == IAC ? iac : cr), 2);
849 p++;
850 }
851 }
852
853 return telnet->bufsize;
854 }
855
856 /*
857 * Called to query the current socket sendability status.
858 */
859 static int telnet_sendbuffer(void *handle)
860 {
861 Telnet telnet = (Telnet) handle;
862 return telnet->bufsize;
863 }
864
865 /*
866 * Called to set the size of the window from Telnet's POV.
867 */
868 static void telnet_size(void *handle, int width, int height)
869 {
870 Telnet telnet = (Telnet) handle;
871 unsigned char b[24];
872 int n;
873 char *logbuf;
874
875 telnet->term_width = width;
876 telnet->term_height = height;
877
878 if (telnet->s == NULL || telnet->opt_states[o_naws.index] != ACTIVE)
879 return;
880 n = 0;
881 b[n++] = IAC;
882 b[n++] = SB;
883 b[n++] = TELOPT_NAWS;
884 b[n++] = telnet->term_width >> 8;
885 if (b[n-1] == IAC) b[n++] = IAC; /* duplicate any IAC byte occurs */
886 b[n++] = telnet->term_width & 0xFF;
887 if (b[n-1] == IAC) b[n++] = IAC; /* duplicate any IAC byte occurs */
888 b[n++] = telnet->term_height >> 8;
889 if (b[n-1] == IAC) b[n++] = IAC; /* duplicate any IAC byte occurs */
890 b[n++] = telnet->term_height & 0xFF;
891 if (b[n-1] == IAC) b[n++] = IAC; /* duplicate any IAC byte occurs */
892 b[n++] = IAC;
893 b[n++] = SE;
894 telnet->bufsize = sk_write(telnet->s, (char *)b, n);
895 logbuf = dupprintf("client:\tSB NAWS %d,%d",
896 telnet->term_width, telnet->term_height);
897 logevent(telnet->frontend, logbuf);
898 sfree(logbuf);
899 }
900
901 /*
902 * Send Telnet special codes.
903 */
904 static void telnet_special(void *handle, Telnet_Special code)
905 {
906 Telnet telnet = (Telnet) handle;
907 unsigned char b[2];
908
909 if (telnet->s == NULL)
910 return;
911
912 b[0] = IAC;
913 switch (code) {
914 case TS_AYT:
915 b[1] = AYT;
916 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
917 break;
918 case TS_BRK:
919 b[1] = BREAK;
920 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
921 break;
922 case TS_EC:
923 b[1] = EC;
924 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
925 break;
926 case TS_EL:
927 b[1] = EL;
928 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
929 break;
930 case TS_GA:
931 b[1] = GA;
932 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
933 break;
934 case TS_NOP:
935 b[1] = NOP;
936 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
937 break;
938 case TS_ABORT:
939 b[1] = ABORT;
940 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
941 break;
942 case TS_AO:
943 b[1] = AO;
944 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
945 break;
946 case TS_IP:
947 b[1] = IP;
948 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
949 break;
950 case TS_SUSP:
951 b[1] = SUSP;
952 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
953 break;
954 case TS_EOR:
955 b[1] = EOR;
956 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
957 break;
958 case TS_EOF:
959 b[1] = xEOF;
960 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
961 break;
962 case TS_EOL:
963 /* In BINARY mode, CR-LF becomes just CR -
964 * and without the NUL suffix too. */
965 if (telnet->opt_states[o_we_bin.index] == ACTIVE)
966 telnet->bufsize = sk_write(telnet->s, "\r", 1);
967 else
968 telnet->bufsize = sk_write(telnet->s, "\r\n", 2);
969 break;
970 case TS_SYNCH:
971 b[1] = DM;
972 telnet->bufsize = sk_write(telnet->s, (char *)b, 1);
973 telnet->bufsize = sk_write_oob(telnet->s, (char *)(b + 1), 1);
974 break;
975 case TS_RECHO:
976 if (telnet->opt_states[o_echo.index] == INACTIVE ||
977 telnet->opt_states[o_echo.index] == REALLY_INACTIVE) {
978 telnet->opt_states[o_echo.index] = REQUESTED;
979 send_opt(telnet, o_echo.send, o_echo.option);
980 }
981 break;
982 case TS_LECHO:
983 if (telnet->opt_states[o_echo.index] == ACTIVE) {
984 telnet->opt_states[o_echo.index] = REQUESTED;
985 send_opt(telnet, o_echo.nsend, o_echo.option);
986 }
987 break;
988 case TS_PING:
989 if (telnet->opt_states[o_they_sga.index] == ACTIVE) {
990 b[1] = NOP;
991 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
992 }
993 break;
994 default:
995 break; /* never heard of it */
996 }
997 }
998
999 static const struct telnet_special *telnet_get_specials(void *handle)
1000 {
1001 static const struct telnet_special specials[] = {
1002 {"Are You There", TS_AYT},
1003 {"Break", TS_BRK},
1004 {"Synch", TS_SYNCH},
1005 {"Erase Character", TS_EC},
1006 {"Erase Line", TS_EL},
1007 {"Go Ahead", TS_GA},
1008 {"No Operation", TS_NOP},
1009 {NULL, TS_SEP},
1010 {"Abort Process", TS_ABORT},
1011 {"Abort Output", TS_AO},
1012 {"Interrupt Process", TS_IP},
1013 {"Suspend Process", TS_SUSP},
1014 {NULL, TS_SEP},
1015 {"End Of Record", TS_EOR},
1016 {"End Of File", TS_EOF},
1017 {NULL, TS_EXITMENU}
1018 };
1019 return specials;
1020 }
1021
1022 static Socket telnet_socket(void *handle)
1023 {
1024 Telnet telnet = (Telnet) handle;
1025 return telnet->s;
1026 }
1027
1028 static int telnet_sendok(void *handle)
1029 {
1030 /* Telnet telnet = (Telnet) handle; */
1031 return 1;
1032 }
1033
1034 static void telnet_unthrottle(void *handle, int backlog)
1035 {
1036 Telnet telnet = (Telnet) handle;
1037 sk_set_frozen(telnet->s, backlog > TELNET_MAX_BACKLOG);
1038 }
1039
1040 static int telnet_ldisc(void *handle, int option)
1041 {
1042 Telnet telnet = (Telnet) handle;
1043 if (option == LD_ECHO)
1044 return telnet->echoing;
1045 if (option == LD_EDIT)
1046 return telnet->editing;
1047 return FALSE;
1048 }
1049
1050 static void telnet_provide_ldisc(void *handle, void *ldisc)
1051 {
1052 Telnet telnet = (Telnet) handle;
1053 telnet->ldisc = ldisc;
1054 }
1055
1056 static void telnet_provide_logctx(void *handle, void *logctx)
1057 {
1058 /* This is a stub. */
1059 }
1060
1061 static int telnet_exitcode(void *handle)
1062 {
1063 Telnet telnet = (Telnet) handle;
1064 if (telnet->s != NULL)
1065 return -1; /* still connected */
1066 else
1067 /* Telnet doesn't transmit exit codes back to the client */
1068 return 0;
1069 }
1070
1071 /*
1072 * cfg_info for Telnet does nothing at all.
1073 */
1074 static int telnet_cfg_info(void *handle)
1075 {
1076 return 0;
1077 }
1078
1079 Backend telnet_backend = {
1080 telnet_init,
1081 telnet_free,
1082 telnet_reconfig,
1083 telnet_send,
1084 telnet_sendbuffer,
1085 telnet_size,
1086 telnet_special,
1087 telnet_get_specials,
1088 telnet_socket,
1089 telnet_exitcode,
1090 telnet_sendok,
1091 telnet_ldisc,
1092 telnet_provide_ldisc,
1093 telnet_provide_logctx,
1094 telnet_unthrottle,
1095 telnet_cfg_info,
1096 23
1097 };
Local modifications for Simon Tatham's `PuTTY' SSH client and terminal emulator