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Support for falling back through the list of addresses returned from
[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
248 Pinger pinger;
249 } *Telnet;
250
251 #define TELNET_MAX_BACKLOG 4096
252
253 #define SB_DELTA 1024
254
255 static void c_write1(Telnet telnet, int c)
256 {
257 int backlog;
258 char cc = (char) c;
259 backlog = from_backend(telnet->frontend, 0, &cc, 1);
260 sk_set_frozen(telnet->s, backlog > TELNET_MAX_BACKLOG);
261 }
262
263 static void log_option(Telnet telnet, char *sender, int cmd, int option)
264 {
265 char *buf;
266 /*
267 * The strange-looking "<?""?>" below is there to avoid a
268 * trigraph - a double question mark followed by > maps to a
269 * closing brace character!
270 */
271 buf = dupprintf("%s:\t%s %s", sender,
272 (cmd == WILL ? "WILL" : cmd == WONT ? "WONT" :
273 cmd == DO ? "DO" : cmd == DONT ? "DONT" : "<?""?>"),
274 telopt(option));
275 logevent(telnet->frontend, buf);
276 sfree(buf);
277 }
278
279 static void send_opt(Telnet telnet, int cmd, int option)
280 {
281 unsigned char b[3];
282
283 b[0] = IAC;
284 b[1] = cmd;
285 b[2] = option;
286 telnet->bufsize = sk_write(telnet->s, (char *)b, 3);
287 log_option(telnet, "client", cmd, option);
288 }
289
290 static void deactivate_option(Telnet telnet, const struct Opt *o)
291 {
292 if (telnet->opt_states[o->index] == REQUESTED ||
293 telnet->opt_states[o->index] == ACTIVE)
294 send_opt(telnet, o->nsend, o->option);
295 telnet->opt_states[o->index] = REALLY_INACTIVE;
296 }
297
298 /*
299 * Generate side effects of enabling or disabling an option.
300 */
301 static void option_side_effects(Telnet telnet, const struct Opt *o, int enabled)
302 {
303 if (o->option == TELOPT_ECHO && o->send == DO)
304 telnet->echoing = !enabled;
305 else if (o->option == TELOPT_SGA && o->send == DO)
306 telnet->editing = !enabled;
307 if (telnet->ldisc) /* cause ldisc to notice the change */
308 ldisc_send(telnet->ldisc, NULL, 0, 0);
309
310 /* Ensure we get the minimum options */
311 if (!telnet->activated) {
312 if (telnet->opt_states[o_echo.index] == INACTIVE) {
313 telnet->opt_states[o_echo.index] = REQUESTED;
314 send_opt(telnet, o_echo.send, o_echo.option);
315 }
316 if (telnet->opt_states[o_we_sga.index] == INACTIVE) {
317 telnet->opt_states[o_we_sga.index] = REQUESTED;
318 send_opt(telnet, o_we_sga.send, o_we_sga.option);
319 }
320 if (telnet->opt_states[o_they_sga.index] == INACTIVE) {
321 telnet->opt_states[o_they_sga.index] = REQUESTED;
322 send_opt(telnet, o_they_sga.send, o_they_sga.option);
323 }
324 telnet->activated = TRUE;
325 }
326 }
327
328 static void activate_option(Telnet telnet, const struct Opt *o)
329 {
330 if (o->send == WILL && o->option == TELOPT_NAWS)
331 telnet_size(telnet, telnet->term_width, telnet->term_height);
332 if (o->send == WILL &&
333 (o->option == TELOPT_NEW_ENVIRON ||
334 o->option == TELOPT_OLD_ENVIRON)) {
335 /*
336 * We may only have one kind of ENVIRON going at a time.
337 * This is a hack, but who cares.
338 */
339 deactivate_option(telnet, o->option ==
340 TELOPT_NEW_ENVIRON ? &o_oenv : &o_nenv);
341 }
342 option_side_effects(telnet, o, 1);
343 }
344
345 static void refused_option(Telnet telnet, const struct Opt *o)
346 {
347 if (o->send == WILL && o->option == TELOPT_NEW_ENVIRON &&
348 telnet->opt_states[o_oenv.index] == INACTIVE) {
349 send_opt(telnet, WILL, TELOPT_OLD_ENVIRON);
350 telnet->opt_states[o_oenv.index] = REQUESTED;
351 }
352 option_side_effects(telnet, o, 0);
353 }
354
355 static void proc_rec_opt(Telnet telnet, int cmd, int option)
356 {
357 const struct Opt *const *o;
358
359 log_option(telnet, "server", cmd, option);
360 for (o = opts; *o; o++) {
361 if ((*o)->option == option && (*o)->ack == cmd) {
362 switch (telnet->opt_states[(*o)->index]) {
363 case REQUESTED:
364 telnet->opt_states[(*o)->index] = ACTIVE;
365 activate_option(telnet, *o);
366 break;
367 case ACTIVE:
368 break;
369 case INACTIVE:
370 telnet->opt_states[(*o)->index] = ACTIVE;
371 send_opt(telnet, (*o)->send, option);
372 activate_option(telnet, *o);
373 break;
374 case REALLY_INACTIVE:
375 send_opt(telnet, (*o)->nsend, option);
376 break;
377 }
378 return;
379 } else if ((*o)->option == option && (*o)->nak == cmd) {
380 switch (telnet->opt_states[(*o)->index]) {
381 case REQUESTED:
382 telnet->opt_states[(*o)->index] = INACTIVE;
383 refused_option(telnet, *o);
384 break;
385 case ACTIVE:
386 telnet->opt_states[(*o)->index] = INACTIVE;
387 send_opt(telnet, (*o)->nsend, option);
388 option_side_effects(telnet, *o, 0);
389 break;
390 case INACTIVE:
391 case REALLY_INACTIVE:
392 break;
393 }
394 return;
395 }
396 }
397 /*
398 * If we reach here, the option was one we weren't prepared to
399 * cope with. So send a negative ack.
400 */
401 send_opt(telnet, (cmd == WILL ? DONT : WONT), option);
402 }
403
404 static void process_subneg(Telnet telnet)
405 {
406 unsigned char b[2048], *p, *q;
407 int var, value, n;
408 char *e;
409
410 switch (telnet->sb_opt) {
411 case TELOPT_TSPEED:
412 if (telnet->sb_len == 1 && telnet->sb_buf[0] == TELQUAL_SEND) {
413 char *logbuf;
414 b[0] = IAC;
415 b[1] = SB;
416 b[2] = TELOPT_TSPEED;
417 b[3] = TELQUAL_IS;
418 strcpy((char *)(b + 4), telnet->cfg.termspeed);
419 n = 4 + strlen(telnet->cfg.termspeed);
420 b[n] = IAC;
421 b[n + 1] = SE;
422 telnet->bufsize = sk_write(telnet->s, (char *)b, n + 2);
423 logevent(telnet->frontend, "server:\tSB TSPEED SEND");
424 logbuf = dupprintf("client:\tSB TSPEED IS %s", telnet->cfg.termspeed);
425 logevent(telnet->frontend, logbuf);
426 sfree(logbuf);
427 } else
428 logevent(telnet->frontend, "server:\tSB TSPEED <something weird>");
429 break;
430 case TELOPT_TTYPE:
431 if (telnet->sb_len == 1 && telnet->sb_buf[0] == TELQUAL_SEND) {
432 char *logbuf;
433 b[0] = IAC;
434 b[1] = SB;
435 b[2] = TELOPT_TTYPE;
436 b[3] = TELQUAL_IS;
437 for (n = 0; telnet->cfg.termtype[n]; n++)
438 b[n + 4] = (telnet->cfg.termtype[n] >= 'a'
439 && telnet->cfg.termtype[n] <=
440 'z' ? telnet->cfg.termtype[n] + 'A' -
441 'a' : telnet->cfg.termtype[n]);
442 b[n + 4] = IAC;
443 b[n + 5] = SE;
444 telnet->bufsize = sk_write(telnet->s, (char *)b, n + 6);
445 b[n + 4] = 0;
446 logevent(telnet->frontend, "server:\tSB TTYPE SEND");
447 logbuf = dupprintf("client:\tSB TTYPE IS %s", b + 4);
448 logevent(telnet->frontend, logbuf);
449 sfree(logbuf);
450 } else
451 logevent(telnet->frontend, "server:\tSB TTYPE <something weird>\r\n");
452 break;
453 case TELOPT_OLD_ENVIRON:
454 case TELOPT_NEW_ENVIRON:
455 p = telnet->sb_buf;
456 q = p + telnet->sb_len;
457 if (p < q && *p == TELQUAL_SEND) {
458 char *logbuf;
459 p++;
460 logbuf = dupprintf("server:\tSB %s SEND", telopt(telnet->sb_opt));
461 logevent(telnet->frontend, logbuf);
462 sfree(logbuf);
463 if (telnet->sb_opt == TELOPT_OLD_ENVIRON) {
464 if (telnet->cfg.rfc_environ) {
465 value = RFC_VALUE;
466 var = RFC_VAR;
467 } else {
468 value = BSD_VALUE;
469 var = BSD_VAR;
470 }
471 /*
472 * Try to guess the sense of VAR and VALUE.
473 */
474 while (p < q) {
475 if (*p == RFC_VAR) {
476 value = RFC_VALUE;
477 var = RFC_VAR;
478 } else if (*p == BSD_VAR) {
479 value = BSD_VALUE;
480 var = BSD_VAR;
481 }
482 p++;
483 }
484 } else {
485 /*
486 * With NEW_ENVIRON, the sense of VAR and VALUE
487 * isn't in doubt.
488 */
489 value = RFC_VALUE;
490 var = RFC_VAR;
491 }
492 b[0] = IAC;
493 b[1] = SB;
494 b[2] = telnet->sb_opt;
495 b[3] = TELQUAL_IS;
496 n = 4;
497 e = telnet->cfg.environmt;
498 while (*e) {
499 b[n++] = var;
500 while (*e && *e != '\t')
501 b[n++] = *e++;
502 if (*e == '\t')
503 e++;
504 b[n++] = value;
505 while (*e)
506 b[n++] = *e++;
507 e++;
508 }
509 if (*telnet->cfg.username) {
510 b[n++] = var;
511 b[n++] = 'U';
512 b[n++] = 'S';
513 b[n++] = 'E';
514 b[n++] = 'R';
515 b[n++] = value;
516 e = telnet->cfg.username;
517 while (*e)
518 b[n++] = *e++;
519 }
520 b[n++] = IAC;
521 b[n++] = SE;
522 telnet->bufsize = sk_write(telnet->s, (char *)b, n);
523 logbuf = dupprintf("client:\tSB %s IS %s%s%s%s",
524 telopt(telnet->sb_opt),
525 *telnet->cfg.username ? "USER=" : "",
526 telnet->cfg.username,
527 *telnet->cfg.username ? " " : "",
528 n == 6 ? "<nothing>" :
529 (*telnet->cfg.environmt ? "<stuff>" : ""));
530 logevent(telnet->frontend, logbuf);
531 sfree(logbuf);
532 }
533 break;
534 }
535 }
536
537 static void do_telnet_read(Telnet telnet, char *buf, int len)
538 {
539
540 while (len--) {
541 int c = (unsigned char) *buf++;
542
543 switch (telnet->state) {
544 case TOP_LEVEL:
545 case SEENCR:
546 if (c == NUL && telnet->state == SEENCR)
547 telnet->state = TOP_LEVEL;
548 else if (c == IAC)
549 telnet->state = SEENIAC;
550 else {
551 if (!telnet->in_synch)
552 c_write1(telnet, c);
553
554 #if 1
555 /* I can't get the F***ing winsock to insert the urgent IAC
556 * into the right position! Even with SO_OOBINLINE it gives
557 * it to recv too soon. And of course the DM byte (that
558 * arrives in the same packet!) appears several K later!!
559 *
560 * Oh well, we do get the DM in the right place so I'll
561 * just stop hiding on the next 0xf2 and hope for the best.
562 */
563 else if (c == DM)
564 telnet->in_synch = 0;
565 #endif
566 if (c == CR && telnet->opt_states[o_they_bin.index] != ACTIVE)
567 telnet->state = SEENCR;
568 else
569 telnet->state = TOP_LEVEL;
570 }
571 break;
572 case SEENIAC:
573 if (c == DO)
574 telnet->state = SEENDO;
575 else if (c == DONT)
576 telnet->state = SEENDONT;
577 else if (c == WILL)
578 telnet->state = SEENWILL;
579 else if (c == WONT)
580 telnet->state = SEENWONT;
581 else if (c == SB)
582 telnet->state = SEENSB;
583 else if (c == DM) {
584 telnet->in_synch = 0;
585 telnet->state = TOP_LEVEL;
586 } else {
587 /* ignore everything else; print it if it's IAC */
588 if (c == IAC) {
589 c_write1(telnet, c);
590 }
591 telnet->state = TOP_LEVEL;
592 }
593 break;
594 case SEENWILL:
595 proc_rec_opt(telnet, WILL, c);
596 telnet->state = TOP_LEVEL;
597 break;
598 case SEENWONT:
599 proc_rec_opt(telnet, WONT, c);
600 telnet->state = TOP_LEVEL;
601 break;
602 case SEENDO:
603 proc_rec_opt(telnet, DO, c);
604 telnet->state = TOP_LEVEL;
605 break;
606 case SEENDONT:
607 proc_rec_opt(telnet, DONT, c);
608 telnet->state = TOP_LEVEL;
609 break;
610 case SEENSB:
611 telnet->sb_opt = c;
612 telnet->sb_len = 0;
613 telnet->state = SUBNEGOT;
614 break;
615 case SUBNEGOT:
616 if (c == IAC)
617 telnet->state = SUBNEG_IAC;
618 else {
619 subneg_addchar:
620 if (telnet->sb_len >= telnet->sb_size) {
621 telnet->sb_size += SB_DELTA;
622 telnet->sb_buf = sresize(telnet->sb_buf, telnet->sb_size,
623 unsigned char);
624 }
625 telnet->sb_buf[telnet->sb_len++] = c;
626 telnet->state = SUBNEGOT; /* in case we came here by goto */
627 }
628 break;
629 case SUBNEG_IAC:
630 if (c != SE)
631 goto subneg_addchar; /* yes, it's a hack, I know, but... */
632 else {
633 process_subneg(telnet);
634 telnet->state = TOP_LEVEL;
635 }
636 break;
637 }
638 }
639 }
640
641 static void telnet_log(Plug plug, int type, SockAddr addr, int port,
642 const char *error_msg, int error_code)
643 {
644 Telnet telnet = (Telnet) plug;
645 char addrbuf[256], *msg;
646
647 sk_getaddr(addr, addrbuf, lenof(addrbuf));
648
649 if (type == 0)
650 msg = dupprintf("Connecting to %s port %d", addrbuf, port);
651 else
652 msg = dupprintf("Failed to connect to %s: %s", addrbuf, error_msg);
653
654 logevent(telnet->frontend, msg);
655 }
656
657 static int telnet_closing(Plug plug, const char *error_msg, int error_code,
658 int calling_back)
659 {
660 Telnet telnet = (Telnet) plug;
661
662 if (telnet->s) {
663 sk_close(telnet->s);
664 telnet->s = NULL;
665 notify_remote_exit(telnet->frontend);
666 }
667 if (error_msg) {
668 logevent(telnet->frontend, error_msg);
669 connection_fatal(telnet->frontend, "%s", error_msg);
670 }
671 /* Otherwise, the remote side closed the connection normally. */
672 return 0;
673 }
674
675 static int telnet_receive(Plug plug, int urgent, char *data, int len)
676 {
677 Telnet telnet = (Telnet) plug;
678 if (urgent)
679 telnet->in_synch = TRUE;
680 do_telnet_read(telnet, data, len);
681 return 1;
682 }
683
684 static void telnet_sent(Plug plug, int bufsize)
685 {
686 Telnet telnet = (Telnet) plug;
687 telnet->bufsize = bufsize;
688 }
689
690 /*
691 * Called to set up the Telnet connection.
692 *
693 * Returns an error message, or NULL on success.
694 *
695 * Also places the canonical host name into `realhost'. It must be
696 * freed by the caller.
697 */
698 static const char *telnet_init(void *frontend_handle, void **backend_handle,
699 Config *cfg,
700 char *host, int port, char **realhost,
701 int nodelay, int keepalive)
702 {
703 static const struct plug_function_table fn_table = {
704 telnet_log,
705 telnet_closing,
706 telnet_receive,
707 telnet_sent
708 };
709 SockAddr addr;
710 const char *err;
711 Telnet telnet;
712
713 telnet = snew(struct telnet_tag);
714 telnet->fn = &fn_table;
715 telnet->cfg = *cfg; /* STRUCTURE COPY */
716 telnet->s = NULL;
717 telnet->echoing = TRUE;
718 telnet->editing = TRUE;
719 telnet->activated = FALSE;
720 telnet->sb_buf = NULL;
721 telnet->sb_size = 0;
722 telnet->frontend = frontend_handle;
723 telnet->term_width = telnet->cfg.width;
724 telnet->term_height = telnet->cfg.height;
725 telnet->state = TOP_LEVEL;
726 telnet->ldisc = NULL;
727 telnet->pinger = NULL;
728 *backend_handle = telnet;
729
730 /*
731 * Try to find host.
732 */
733 {
734 char *buf;
735 buf = dupprintf("Looking up host \"%s\"%s", host,
736 (cfg->addressfamily == ADDRTYPE_IPV4 ? " (IPv4)" :
737 (cfg->addressfamily == ADDRTYPE_IPV6 ? " (IPv6)" :
738 "")));
739 logevent(telnet->frontend, buf);
740 sfree(buf);
741 }
742 addr = name_lookup(host, port, realhost, &telnet->cfg, cfg->addressfamily);
743 if ((err = sk_addr_error(addr)) != NULL) {
744 sk_addr_free(addr);
745 return err;
746 }
747
748 if (port < 0)
749 port = 23; /* default telnet port */
750
751 /*
752 * Open socket.
753 */
754 telnet->s = new_connection(addr, *realhost, port, 0, 1,
755 nodelay, keepalive, (Plug) telnet, &telnet->cfg);
756 if ((err = sk_socket_error(telnet->s)) != NULL)
757 return err;
758
759 telnet->pinger = pinger_new(&telnet->cfg, &telnet_backend, telnet);
760
761 /*
762 * Initialise option states.
763 */
764 if (telnet->cfg.passive_telnet) {
765 const struct Opt *const *o;
766
767 for (o = opts; *o; o++)
768 telnet->opt_states[(*o)->index] = INACTIVE;
769 } else {
770 const struct Opt *const *o;
771
772 for (o = opts; *o; o++) {
773 telnet->opt_states[(*o)->index] = (*o)->initial_state;
774 if (telnet->opt_states[(*o)->index] == REQUESTED)
775 send_opt(telnet, (*o)->send, (*o)->option);
776 }
777 telnet->activated = TRUE;
778 }
779
780 /*
781 * Set up SYNCH state.
782 */
783 telnet->in_synch = FALSE;
784
785 /*
786 * We can send special commands from the start.
787 */
788 update_specials_menu(telnet->frontend);
789
790 return NULL;
791 }
792
793 static void telnet_free(void *handle)
794 {
795 Telnet telnet = (Telnet) handle;
796
797 sfree(telnet->sb_buf);
798 if (telnet->s)
799 sk_close(telnet->s);
800 if (telnet->pinger)
801 pinger_free(telnet->pinger);
802 sfree(telnet);
803 }
804 /*
805 * Reconfigure the Telnet backend. There's no immediate action
806 * necessary, in this backend: we just save the fresh config for
807 * any subsequent negotiations.
808 */
809 static void telnet_reconfig(void *handle, Config *cfg)
810 {
811 Telnet telnet = (Telnet) handle;
812 pinger_reconfig(telnet->pinger, &telnet->cfg, cfg);
813 telnet->cfg = *cfg; /* STRUCTURE COPY */
814 }
815
816 /*
817 * Called to send data down the Telnet connection.
818 */
819 static int telnet_send(void *handle, char *buf, int len)
820 {
821 Telnet telnet = (Telnet) handle;
822 unsigned char *p, *end;
823 static const unsigned char iac[2] = { IAC, IAC };
824 static const unsigned char cr[2] = { CR, NUL };
825 #if 0
826 static const unsigned char nl[2] = { CR, LF };
827 #endif
828
829 if (telnet->s == NULL)
830 return 0;
831
832 p = (unsigned char *)buf;
833 end = (unsigned char *)(buf + len);
834 while (p < end) {
835 unsigned char *q = p;
836
837 while (p < end && iswritable(*p))
838 p++;
839 telnet->bufsize = sk_write(telnet->s, (char *)q, p - q);
840
841 while (p < end && !iswritable(*p)) {
842 telnet->bufsize =
843 sk_write(telnet->s, (char *)(*p == IAC ? iac : cr), 2);
844 p++;
845 }
846 }
847
848 return telnet->bufsize;
849 }
850
851 /*
852 * Called to query the current socket sendability status.
853 */
854 static int telnet_sendbuffer(void *handle)
855 {
856 Telnet telnet = (Telnet) handle;
857 return telnet->bufsize;
858 }
859
860 /*
861 * Called to set the size of the window from Telnet's POV.
862 */
863 static void telnet_size(void *handle, int width, int height)
864 {
865 Telnet telnet = (Telnet) handle;
866 unsigned char b[24];
867 int n;
868 char *logbuf;
869
870 telnet->term_width = width;
871 telnet->term_height = height;
872
873 if (telnet->s == NULL || telnet->opt_states[o_naws.index] != ACTIVE)
874 return;
875 n = 0;
876 b[n++] = IAC;
877 b[n++] = SB;
878 b[n++] = TELOPT_NAWS;
879 b[n++] = telnet->term_width >> 8;
880 if (b[n-1] == IAC) b[n++] = IAC; /* duplicate any IAC byte occurs */
881 b[n++] = telnet->term_width & 0xFF;
882 if (b[n-1] == IAC) b[n++] = IAC; /* duplicate any IAC byte occurs */
883 b[n++] = telnet->term_height >> 8;
884 if (b[n-1] == IAC) b[n++] = IAC; /* duplicate any IAC byte occurs */
885 b[n++] = telnet->term_height & 0xFF;
886 if (b[n-1] == IAC) b[n++] = IAC; /* duplicate any IAC byte occurs */
887 b[n++] = IAC;
888 b[n++] = SE;
889 telnet->bufsize = sk_write(telnet->s, (char *)b, n);
890 logbuf = dupprintf("client:\tSB NAWS %d,%d",
891 telnet->term_width, telnet->term_height);
892 logevent(telnet->frontend, logbuf);
893 sfree(logbuf);
894 }
895
896 /*
897 * Send Telnet special codes.
898 */
899 static void telnet_special(void *handle, Telnet_Special code)
900 {
901 Telnet telnet = (Telnet) handle;
902 unsigned char b[2];
903
904 if (telnet->s == NULL)
905 return;
906
907 b[0] = IAC;
908 switch (code) {
909 case TS_AYT:
910 b[1] = AYT;
911 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
912 break;
913 case TS_BRK:
914 b[1] = BREAK;
915 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
916 break;
917 case TS_EC:
918 b[1] = EC;
919 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
920 break;
921 case TS_EL:
922 b[1] = EL;
923 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
924 break;
925 case TS_GA:
926 b[1] = GA;
927 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
928 break;
929 case TS_NOP:
930 b[1] = NOP;
931 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
932 break;
933 case TS_ABORT:
934 b[1] = ABORT;
935 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
936 break;
937 case TS_AO:
938 b[1] = AO;
939 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
940 break;
941 case TS_IP:
942 b[1] = IP;
943 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
944 break;
945 case TS_SUSP:
946 b[1] = SUSP;
947 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
948 break;
949 case TS_EOR:
950 b[1] = EOR;
951 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
952 break;
953 case TS_EOF:
954 b[1] = xEOF;
955 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
956 break;
957 case TS_EOL:
958 /* In BINARY mode, CR-LF becomes just CR -
959 * and without the NUL suffix too. */
960 if (telnet->opt_states[o_we_bin.index] == ACTIVE)
961 telnet->bufsize = sk_write(telnet->s, "\r", 1);
962 else
963 telnet->bufsize = sk_write(telnet->s, "\r\n", 2);
964 break;
965 case TS_SYNCH:
966 b[1] = DM;
967 telnet->bufsize = sk_write(telnet->s, (char *)b, 1);
968 telnet->bufsize = sk_write_oob(telnet->s, (char *)(b + 1), 1);
969 break;
970 case TS_RECHO:
971 if (telnet->opt_states[o_echo.index] == INACTIVE ||
972 telnet->opt_states[o_echo.index] == REALLY_INACTIVE) {
973 telnet->opt_states[o_echo.index] = REQUESTED;
974 send_opt(telnet, o_echo.send, o_echo.option);
975 }
976 break;
977 case TS_LECHO:
978 if (telnet->opt_states[o_echo.index] == ACTIVE) {
979 telnet->opt_states[o_echo.index] = REQUESTED;
980 send_opt(telnet, o_echo.nsend, o_echo.option);
981 }
982 break;
983 case TS_PING:
984 if (telnet->opt_states[o_they_sga.index] == ACTIVE) {
985 b[1] = NOP;
986 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
987 }
988 break;
989 default:
990 break; /* never heard of it */
991 }
992 }
993
994 static const struct telnet_special *telnet_get_specials(void *handle)
995 {
996 static const struct telnet_special specials[] = {
997 {"Are You There", TS_AYT},
998 {"Break", TS_BRK},
999 {"Synch", TS_SYNCH},
1000 {"Erase Character", TS_EC},
1001 {"Erase Line", TS_EL},
1002 {"Go Ahead", TS_GA},
1003 {"No Operation", TS_NOP},
1004 {NULL, TS_SEP},
1005 {"Abort Process", TS_ABORT},
1006 {"Abort Output", TS_AO},
1007 {"Interrupt Process", TS_IP},
1008 {"Suspend Process", TS_SUSP},
1009 {NULL, TS_SEP},
1010 {"End Of Record", TS_EOR},
1011 {"End Of File", TS_EOF},
1012 {NULL, TS_EXITMENU}
1013 };
1014 return specials;
1015 }
1016
1017 static Socket telnet_socket(void *handle)
1018 {
1019 Telnet telnet = (Telnet) handle;
1020 return telnet->s;
1021 }
1022
1023 static int telnet_sendok(void *handle)
1024 {
1025 /* Telnet telnet = (Telnet) handle; */
1026 return 1;
1027 }
1028
1029 static void telnet_unthrottle(void *handle, int backlog)
1030 {
1031 Telnet telnet = (Telnet) handle;
1032 sk_set_frozen(telnet->s, backlog > TELNET_MAX_BACKLOG);
1033 }
1034
1035 static int telnet_ldisc(void *handle, int option)
1036 {
1037 Telnet telnet = (Telnet) handle;
1038 if (option == LD_ECHO)
1039 return telnet->echoing;
1040 if (option == LD_EDIT)
1041 return telnet->editing;
1042 return FALSE;
1043 }
1044
1045 static void telnet_provide_ldisc(void *handle, void *ldisc)
1046 {
1047 Telnet telnet = (Telnet) handle;
1048 telnet->ldisc = ldisc;
1049 }
1050
1051 static void telnet_provide_logctx(void *handle, void *logctx)
1052 {
1053 /* This is a stub. */
1054 }
1055
1056 static int telnet_exitcode(void *handle)
1057 {
1058 Telnet telnet = (Telnet) handle;
1059 if (telnet->s != NULL)
1060 return -1; /* still connected */
1061 else
1062 /* Telnet doesn't transmit exit codes back to the client */
1063 return 0;
1064 }
1065
1066 /*
1067 * cfg_info for Telnet does nothing at all.
1068 */
1069 static int telnet_cfg_info(void *handle)
1070 {
1071 return 0;
1072 }
1073
1074 Backend telnet_backend = {
1075 telnet_init,
1076 telnet_free,
1077 telnet_reconfig,
1078 telnet_send,
1079 telnet_sendbuffer,
1080 telnet_size,
1081 telnet_special,
1082 telnet_get_specials,
1083 telnet_socket,
1084 telnet_exitcode,
1085 telnet_sendok,
1086 telnet_ldisc,
1087 telnet_provide_ldisc,
1088 telnet_provide_logctx,
1089 telnet_unthrottle,
1090 telnet_cfg_info,
1091 23
1092 };
Local modifications for Simon Tatham's `PuTTY' SSH client and terminal emulator