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Have one call to from_backend() per call to do_telnet_read(),
[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_write(Telnet telnet, char *buf, int len)
258 {
259 int backlog;
260 backlog = from_backend(telnet->frontend, 0, buf, len);
261 sk_set_frozen(telnet->s, backlog > TELNET_MAX_BACKLOG);
262 }
263
264 static void log_option(Telnet telnet, char *sender, int cmd, int option)
265 {
266 char *buf;
267 /*
268 * The strange-looking "<?""?>" below is there to avoid a
269 * trigraph - a double question mark followed by > maps to a
270 * closing brace character!
271 */
272 buf = dupprintf("%s:\t%s %s", sender,
273 (cmd == WILL ? "WILL" : cmd == WONT ? "WONT" :
274 cmd == DO ? "DO" : cmd == DONT ? "DONT" : "<?""?>"),
275 telopt(option));
276 logevent(telnet->frontend, buf);
277 sfree(buf);
278 }
279
280 static void send_opt(Telnet telnet, int cmd, int option)
281 {
282 unsigned char b[3];
283
284 b[0] = IAC;
285 b[1] = cmd;
286 b[2] = option;
287 telnet->bufsize = sk_write(telnet->s, (char *)b, 3);
288 log_option(telnet, "client", cmd, option);
289 }
290
291 static void deactivate_option(Telnet telnet, const struct Opt *o)
292 {
293 if (telnet->opt_states[o->index] == REQUESTED ||
294 telnet->opt_states[o->index] == ACTIVE)
295 send_opt(telnet, o->nsend, o->option);
296 telnet->opt_states[o->index] = REALLY_INACTIVE;
297 }
298
299 /*
300 * Generate side effects of enabling or disabling an option.
301 */
302 static void option_side_effects(Telnet telnet, const struct Opt *o, int enabled)
303 {
304 if (o->option == TELOPT_ECHO && o->send == DO)
305 telnet->echoing = !enabled;
306 else if (o->option == TELOPT_SGA && o->send == DO)
307 telnet->editing = !enabled;
308 if (telnet->ldisc) /* cause ldisc to notice the change */
309 ldisc_send(telnet->ldisc, NULL, 0, 0);
310
311 /* Ensure we get the minimum options */
312 if (!telnet->activated) {
313 if (telnet->opt_states[o_echo.index] == INACTIVE) {
314 telnet->opt_states[o_echo.index] = REQUESTED;
315 send_opt(telnet, o_echo.send, o_echo.option);
316 }
317 if (telnet->opt_states[o_we_sga.index] == INACTIVE) {
318 telnet->opt_states[o_we_sga.index] = REQUESTED;
319 send_opt(telnet, o_we_sga.send, o_we_sga.option);
320 }
321 if (telnet->opt_states[o_they_sga.index] == INACTIVE) {
322 telnet->opt_states[o_they_sga.index] = REQUESTED;
323 send_opt(telnet, o_they_sga.send, o_they_sga.option);
324 }
325 telnet->activated = TRUE;
326 }
327 }
328
329 static void activate_option(Telnet telnet, const struct Opt *o)
330 {
331 if (o->send == WILL && o->option == TELOPT_NAWS)
332 telnet_size(telnet, telnet->term_width, telnet->term_height);
333 if (o->send == WILL &&
334 (o->option == TELOPT_NEW_ENVIRON ||
335 o->option == TELOPT_OLD_ENVIRON)) {
336 /*
337 * We may only have one kind of ENVIRON going at a time.
338 * This is a hack, but who cares.
339 */
340 deactivate_option(telnet, o->option ==
341 TELOPT_NEW_ENVIRON ? &o_oenv : &o_nenv);
342 }
343 option_side_effects(telnet, o, 1);
344 }
345
346 static void refused_option(Telnet telnet, const struct Opt *o)
347 {
348 if (o->send == WILL && o->option == TELOPT_NEW_ENVIRON &&
349 telnet->opt_states[o_oenv.index] == INACTIVE) {
350 send_opt(telnet, WILL, TELOPT_OLD_ENVIRON);
351 telnet->opt_states[o_oenv.index] = REQUESTED;
352 }
353 option_side_effects(telnet, o, 0);
354 }
355
356 static void proc_rec_opt(Telnet telnet, int cmd, int option)
357 {
358 const struct Opt *const *o;
359
360 log_option(telnet, "server", cmd, option);
361 for (o = opts; *o; o++) {
362 if ((*o)->option == option && (*o)->ack == cmd) {
363 switch (telnet->opt_states[(*o)->index]) {
364 case REQUESTED:
365 telnet->opt_states[(*o)->index] = ACTIVE;
366 activate_option(telnet, *o);
367 break;
368 case ACTIVE:
369 break;
370 case INACTIVE:
371 telnet->opt_states[(*o)->index] = ACTIVE;
372 send_opt(telnet, (*o)->send, option);
373 activate_option(telnet, *o);
374 break;
375 case REALLY_INACTIVE:
376 send_opt(telnet, (*o)->nsend, option);
377 break;
378 }
379 return;
380 } else if ((*o)->option == option && (*o)->nak == cmd) {
381 switch (telnet->opt_states[(*o)->index]) {
382 case REQUESTED:
383 telnet->opt_states[(*o)->index] = INACTIVE;
384 refused_option(telnet, *o);
385 break;
386 case ACTIVE:
387 telnet->opt_states[(*o)->index] = INACTIVE;
388 send_opt(telnet, (*o)->nsend, option);
389 option_side_effects(telnet, *o, 0);
390 break;
391 case INACTIVE:
392 case REALLY_INACTIVE:
393 break;
394 }
395 return;
396 }
397 }
398 /*
399 * If we reach here, the option was one we weren't prepared to
400 * cope with. If the request was positive (WILL or DO), we send
401 * a negative ack to indicate refusal. If the request was
402 * negative (WONT / DONT), we must do nothing.
403 */
404 if (cmd == WILL || cmd == DO)
405 send_opt(telnet, (cmd == WILL ? DONT : WONT), option);
406 }
407
408 static void process_subneg(Telnet telnet)
409 {
410 unsigned char b[2048], *p, *q;
411 int var, value, n;
412 char *e;
413
414 switch (telnet->sb_opt) {
415 case TELOPT_TSPEED:
416 if (telnet->sb_len == 1 && telnet->sb_buf[0] == TELQUAL_SEND) {
417 char *logbuf;
418 b[0] = IAC;
419 b[1] = SB;
420 b[2] = TELOPT_TSPEED;
421 b[3] = TELQUAL_IS;
422 strcpy((char *)(b + 4), telnet->cfg.termspeed);
423 n = 4 + strlen(telnet->cfg.termspeed);
424 b[n] = IAC;
425 b[n + 1] = SE;
426 telnet->bufsize = sk_write(telnet->s, (char *)b, n + 2);
427 logevent(telnet->frontend, "server:\tSB TSPEED SEND");
428 logbuf = dupprintf("client:\tSB TSPEED IS %s", telnet->cfg.termspeed);
429 logevent(telnet->frontend, logbuf);
430 sfree(logbuf);
431 } else
432 logevent(telnet->frontend, "server:\tSB TSPEED <something weird>");
433 break;
434 case TELOPT_TTYPE:
435 if (telnet->sb_len == 1 && telnet->sb_buf[0] == TELQUAL_SEND) {
436 char *logbuf;
437 b[0] = IAC;
438 b[1] = SB;
439 b[2] = TELOPT_TTYPE;
440 b[3] = TELQUAL_IS;
441 for (n = 0; telnet->cfg.termtype[n]; n++)
442 b[n + 4] = (telnet->cfg.termtype[n] >= 'a'
443 && telnet->cfg.termtype[n] <=
444 'z' ? telnet->cfg.termtype[n] + 'A' -
445 'a' : telnet->cfg.termtype[n]);
446 b[n + 4] = IAC;
447 b[n + 5] = SE;
448 telnet->bufsize = sk_write(telnet->s, (char *)b, n + 6);
449 b[n + 4] = 0;
450 logevent(telnet->frontend, "server:\tSB TTYPE SEND");
451 logbuf = dupprintf("client:\tSB TTYPE IS %s", b + 4);
452 logevent(telnet->frontend, logbuf);
453 sfree(logbuf);
454 } else
455 logevent(telnet->frontend, "server:\tSB TTYPE <something weird>\r\n");
456 break;
457 case TELOPT_OLD_ENVIRON:
458 case TELOPT_NEW_ENVIRON:
459 p = telnet->sb_buf;
460 q = p + telnet->sb_len;
461 if (p < q && *p == TELQUAL_SEND) {
462 char *logbuf;
463 p++;
464 logbuf = dupprintf("server:\tSB %s SEND", telopt(telnet->sb_opt));
465 logevent(telnet->frontend, logbuf);
466 sfree(logbuf);
467 if (telnet->sb_opt == TELOPT_OLD_ENVIRON) {
468 if (telnet->cfg.rfc_environ) {
469 value = RFC_VALUE;
470 var = RFC_VAR;
471 } else {
472 value = BSD_VALUE;
473 var = BSD_VAR;
474 }
475 /*
476 * Try to guess the sense of VAR and VALUE.
477 */
478 while (p < q) {
479 if (*p == RFC_VAR) {
480 value = RFC_VALUE;
481 var = RFC_VAR;
482 } else if (*p == BSD_VAR) {
483 value = BSD_VALUE;
484 var = BSD_VAR;
485 }
486 p++;
487 }
488 } else {
489 /*
490 * With NEW_ENVIRON, the sense of VAR and VALUE
491 * isn't in doubt.
492 */
493 value = RFC_VALUE;
494 var = RFC_VAR;
495 }
496 b[0] = IAC;
497 b[1] = SB;
498 b[2] = telnet->sb_opt;
499 b[3] = TELQUAL_IS;
500 n = 4;
501 e = telnet->cfg.environmt;
502 while (*e) {
503 b[n++] = var;
504 while (*e && *e != '\t')
505 b[n++] = *e++;
506 if (*e == '\t')
507 e++;
508 b[n++] = value;
509 while (*e)
510 b[n++] = *e++;
511 e++;
512 }
513 if (*telnet->cfg.username) {
514 b[n++] = var;
515 b[n++] = 'U';
516 b[n++] = 'S';
517 b[n++] = 'E';
518 b[n++] = 'R';
519 b[n++] = value;
520 e = telnet->cfg.username;
521 while (*e)
522 b[n++] = *e++;
523 }
524 b[n++] = IAC;
525 b[n++] = SE;
526 telnet->bufsize = sk_write(telnet->s, (char *)b, n);
527 logbuf = dupprintf("client:\tSB %s IS %s%s%s%s",
528 telopt(telnet->sb_opt),
529 *telnet->cfg.username ? "USER=" : "",
530 telnet->cfg.username,
531 *telnet->cfg.username ? " " : "",
532 n == 6 ? "<nothing>" :
533 (*telnet->cfg.environmt ? "<stuff>" : ""));
534 logevent(telnet->frontend, logbuf);
535 sfree(logbuf);
536 }
537 break;
538 }
539 }
540
541 static void do_telnet_read(Telnet telnet, char *buf, int len)
542 {
543 char *outbuf = NULL;
544 int outbuflen = 0, outbufsize = 0;
545
546 #define ADDTOBUF(c) do { \
547 if (outbuflen >= outbufsize) { \
548 outbufsize = outbuflen + 256; \
549 outbuf = sresize(outbuf, outbufsize, char); \
550 } \
551 outbuf[outbuflen++] = (c); \
552 } while (0)
553
554 while (len--) {
555 int c = (unsigned char) *buf++;
556
557 switch (telnet->state) {
558 case TOP_LEVEL:
559 case SEENCR:
560 if (c == NUL && telnet->state == SEENCR)
561 telnet->state = TOP_LEVEL;
562 else if (c == IAC)
563 telnet->state = SEENIAC;
564 else {
565 if (!telnet->in_synch)
566 ADDTOBUF(c);
567
568 #if 1
569 /* I can't get the F***ing winsock to insert the urgent IAC
570 * into the right position! Even with SO_OOBINLINE it gives
571 * it to recv too soon. And of course the DM byte (that
572 * arrives in the same packet!) appears several K later!!
573 *
574 * Oh well, we do get the DM in the right place so I'll
575 * just stop hiding on the next 0xf2 and hope for the best.
576 */
577 else if (c == DM)
578 telnet->in_synch = 0;
579 #endif
580 if (c == CR && telnet->opt_states[o_they_bin.index] != ACTIVE)
581 telnet->state = SEENCR;
582 else
583 telnet->state = TOP_LEVEL;
584 }
585 break;
586 case SEENIAC:
587 if (c == DO)
588 telnet->state = SEENDO;
589 else if (c == DONT)
590 telnet->state = SEENDONT;
591 else if (c == WILL)
592 telnet->state = SEENWILL;
593 else if (c == WONT)
594 telnet->state = SEENWONT;
595 else if (c == SB)
596 telnet->state = SEENSB;
597 else if (c == DM) {
598 telnet->in_synch = 0;
599 telnet->state = TOP_LEVEL;
600 } else {
601 /* ignore everything else; print it if it's IAC */
602 if (c == IAC) {
603 ADDTOBUF(c);
604 }
605 telnet->state = TOP_LEVEL;
606 }
607 break;
608 case SEENWILL:
609 proc_rec_opt(telnet, WILL, c);
610 telnet->state = TOP_LEVEL;
611 break;
612 case SEENWONT:
613 proc_rec_opt(telnet, WONT, c);
614 telnet->state = TOP_LEVEL;
615 break;
616 case SEENDO:
617 proc_rec_opt(telnet, DO, c);
618 telnet->state = TOP_LEVEL;
619 break;
620 case SEENDONT:
621 proc_rec_opt(telnet, DONT, c);
622 telnet->state = TOP_LEVEL;
623 break;
624 case SEENSB:
625 telnet->sb_opt = c;
626 telnet->sb_len = 0;
627 telnet->state = SUBNEGOT;
628 break;
629 case SUBNEGOT:
630 if (c == IAC)
631 telnet->state = SUBNEG_IAC;
632 else {
633 subneg_addchar:
634 if (telnet->sb_len >= telnet->sb_size) {
635 telnet->sb_size += SB_DELTA;
636 telnet->sb_buf = sresize(telnet->sb_buf, telnet->sb_size,
637 unsigned char);
638 }
639 telnet->sb_buf[telnet->sb_len++] = c;
640 telnet->state = SUBNEGOT; /* in case we came here by goto */
641 }
642 break;
643 case SUBNEG_IAC:
644 if (c != SE)
645 goto subneg_addchar; /* yes, it's a hack, I know, but... */
646 else {
647 process_subneg(telnet);
648 telnet->state = TOP_LEVEL;
649 }
650 break;
651 }
652 }
653
654 if (outbuflen)
655 c_write(telnet, outbuf, outbuflen);
656 sfree(outbuf);
657 }
658
659 static void telnet_log(Plug plug, int type, SockAddr addr, int port,
660 const char *error_msg, int error_code)
661 {
662 Telnet telnet = (Telnet) plug;
663 char addrbuf[256], *msg;
664
665 sk_getaddr(addr, addrbuf, lenof(addrbuf));
666
667 if (type == 0)
668 msg = dupprintf("Connecting to %s port %d", addrbuf, port);
669 else
670 msg = dupprintf("Failed to connect to %s: %s", addrbuf, error_msg);
671
672 logevent(telnet->frontend, msg);
673 }
674
675 static int telnet_closing(Plug plug, const char *error_msg, int error_code,
676 int calling_back)
677 {
678 Telnet telnet = (Telnet) plug;
679
680 if (telnet->s) {
681 sk_close(telnet->s);
682 telnet->s = NULL;
683 notify_remote_exit(telnet->frontend);
684 }
685 if (error_msg) {
686 logevent(telnet->frontend, error_msg);
687 connection_fatal(telnet->frontend, "%s", error_msg);
688 }
689 /* Otherwise, the remote side closed the connection normally. */
690 return 0;
691 }
692
693 static int telnet_receive(Plug plug, int urgent, char *data, int len)
694 {
695 Telnet telnet = (Telnet) plug;
696 if (urgent)
697 telnet->in_synch = TRUE;
698 do_telnet_read(telnet, data, len);
699 return 1;
700 }
701
702 static void telnet_sent(Plug plug, int bufsize)
703 {
704 Telnet telnet = (Telnet) plug;
705 telnet->bufsize = bufsize;
706 }
707
708 /*
709 * Called to set up the Telnet connection.
710 *
711 * Returns an error message, or NULL on success.
712 *
713 * Also places the canonical host name into `realhost'. It must be
714 * freed by the caller.
715 */
716 static const char *telnet_init(void *frontend_handle, void **backend_handle,
717 Config *cfg,
718 char *host, int port, char **realhost,
719 int nodelay, int keepalive)
720 {
721 static const struct plug_function_table fn_table = {
722 telnet_log,
723 telnet_closing,
724 telnet_receive,
725 telnet_sent
726 };
727 SockAddr addr;
728 const char *err;
729 Telnet telnet;
730
731 telnet = snew(struct telnet_tag);
732 telnet->fn = &fn_table;
733 telnet->cfg = *cfg; /* STRUCTURE COPY */
734 telnet->s = NULL;
735 telnet->echoing = TRUE;
736 telnet->editing = TRUE;
737 telnet->activated = FALSE;
738 telnet->sb_buf = NULL;
739 telnet->sb_size = 0;
740 telnet->frontend = frontend_handle;
741 telnet->term_width = telnet->cfg.width;
742 telnet->term_height = telnet->cfg.height;
743 telnet->state = TOP_LEVEL;
744 telnet->ldisc = NULL;
745 telnet->pinger = NULL;
746 *backend_handle = telnet;
747
748 /*
749 * Try to find host.
750 */
751 {
752 char *buf;
753 buf = dupprintf("Looking up host \"%s\"%s", host,
754 (cfg->addressfamily == ADDRTYPE_IPV4 ? " (IPv4)" :
755 (cfg->addressfamily == ADDRTYPE_IPV6 ? " (IPv6)" :
756 "")));
757 logevent(telnet->frontend, buf);
758 sfree(buf);
759 }
760 addr = name_lookup(host, port, realhost, &telnet->cfg, cfg->addressfamily);
761 if ((err = sk_addr_error(addr)) != NULL) {
762 sk_addr_free(addr);
763 return err;
764 }
765
766 if (port < 0)
767 port = 23; /* default telnet port */
768
769 /*
770 * Open socket.
771 */
772 telnet->s = new_connection(addr, *realhost, port, 0, 1,
773 nodelay, keepalive, (Plug) telnet, &telnet->cfg);
774 if ((err = sk_socket_error(telnet->s)) != NULL)
775 return err;
776
777 telnet->pinger = pinger_new(&telnet->cfg, &telnet_backend, telnet);
778
779 /*
780 * Initialise option states.
781 */
782 if (telnet->cfg.passive_telnet) {
783 const struct Opt *const *o;
784
785 for (o = opts; *o; o++)
786 telnet->opt_states[(*o)->index] = INACTIVE;
787 } else {
788 const struct Opt *const *o;
789
790 for (o = opts; *o; o++) {
791 telnet->opt_states[(*o)->index] = (*o)->initial_state;
792 if (telnet->opt_states[(*o)->index] == REQUESTED)
793 send_opt(telnet, (*o)->send, (*o)->option);
794 }
795 telnet->activated = TRUE;
796 }
797
798 /*
799 * Set up SYNCH state.
800 */
801 telnet->in_synch = FALSE;
802
803 /*
804 * We can send special commands from the start.
805 */
806 update_specials_menu(telnet->frontend);
807
808 return NULL;
809 }
810
811 static void telnet_free(void *handle)
812 {
813 Telnet telnet = (Telnet) handle;
814
815 sfree(telnet->sb_buf);
816 if (telnet->s)
817 sk_close(telnet->s);
818 if (telnet->pinger)
819 pinger_free(telnet->pinger);
820 sfree(telnet);
821 }
822 /*
823 * Reconfigure the Telnet backend. There's no immediate action
824 * necessary, in this backend: we just save the fresh config for
825 * any subsequent negotiations.
826 */
827 static void telnet_reconfig(void *handle, Config *cfg)
828 {
829 Telnet telnet = (Telnet) handle;
830 pinger_reconfig(telnet->pinger, &telnet->cfg, cfg);
831 telnet->cfg = *cfg; /* STRUCTURE COPY */
832 }
833
834 /*
835 * Called to send data down the Telnet connection.
836 */
837 static int telnet_send(void *handle, char *buf, int len)
838 {
839 Telnet telnet = (Telnet) handle;
840 unsigned char *p, *end;
841 static const unsigned char iac[2] = { IAC, IAC };
842 static const unsigned char cr[2] = { CR, NUL };
843 #if 0
844 static const unsigned char nl[2] = { CR, LF };
845 #endif
846
847 if (telnet->s == NULL)
848 return 0;
849
850 p = (unsigned char *)buf;
851 end = (unsigned char *)(buf + len);
852 while (p < end) {
853 unsigned char *q = p;
854
855 while (p < end && iswritable(*p))
856 p++;
857 telnet->bufsize = sk_write(telnet->s, (char *)q, p - q);
858
859 while (p < end && !iswritable(*p)) {
860 telnet->bufsize =
861 sk_write(telnet->s, (char *)(*p == IAC ? iac : cr), 2);
862 p++;
863 }
864 }
865
866 return telnet->bufsize;
867 }
868
869 /*
870 * Called to query the current socket sendability status.
871 */
872 static int telnet_sendbuffer(void *handle)
873 {
874 Telnet telnet = (Telnet) handle;
875 return telnet->bufsize;
876 }
877
878 /*
879 * Called to set the size of the window from Telnet's POV.
880 */
881 static void telnet_size(void *handle, int width, int height)
882 {
883 Telnet telnet = (Telnet) handle;
884 unsigned char b[24];
885 int n;
886 char *logbuf;
887
888 telnet->term_width = width;
889 telnet->term_height = height;
890
891 if (telnet->s == NULL || telnet->opt_states[o_naws.index] != ACTIVE)
892 return;
893 n = 0;
894 b[n++] = IAC;
895 b[n++] = SB;
896 b[n++] = TELOPT_NAWS;
897 b[n++] = telnet->term_width >> 8;
898 if (b[n-1] == IAC) b[n++] = IAC; /* duplicate any IAC byte occurs */
899 b[n++] = telnet->term_width & 0xFF;
900 if (b[n-1] == IAC) b[n++] = IAC; /* duplicate any IAC byte occurs */
901 b[n++] = telnet->term_height >> 8;
902 if (b[n-1] == IAC) b[n++] = IAC; /* duplicate any IAC byte occurs */
903 b[n++] = telnet->term_height & 0xFF;
904 if (b[n-1] == IAC) b[n++] = IAC; /* duplicate any IAC byte occurs */
905 b[n++] = IAC;
906 b[n++] = SE;
907 telnet->bufsize = sk_write(telnet->s, (char *)b, n);
908 logbuf = dupprintf("client:\tSB NAWS %d,%d",
909 telnet->term_width, telnet->term_height);
910 logevent(telnet->frontend, logbuf);
911 sfree(logbuf);
912 }
913
914 /*
915 * Send Telnet special codes.
916 */
917 static void telnet_special(void *handle, Telnet_Special code)
918 {
919 Telnet telnet = (Telnet) handle;
920 unsigned char b[2];
921
922 if (telnet->s == NULL)
923 return;
924
925 b[0] = IAC;
926 switch (code) {
927 case TS_AYT:
928 b[1] = AYT;
929 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
930 break;
931 case TS_BRK:
932 b[1] = BREAK;
933 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
934 break;
935 case TS_EC:
936 b[1] = EC;
937 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
938 break;
939 case TS_EL:
940 b[1] = EL;
941 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
942 break;
943 case TS_GA:
944 b[1] = GA;
945 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
946 break;
947 case TS_NOP:
948 b[1] = NOP;
949 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
950 break;
951 case TS_ABORT:
952 b[1] = ABORT;
953 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
954 break;
955 case TS_AO:
956 b[1] = AO;
957 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
958 break;
959 case TS_IP:
960 b[1] = IP;
961 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
962 break;
963 case TS_SUSP:
964 b[1] = SUSP;
965 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
966 break;
967 case TS_EOR:
968 b[1] = EOR;
969 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
970 break;
971 case TS_EOF:
972 b[1] = xEOF;
973 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
974 break;
975 case TS_EOL:
976 /* In BINARY mode, CR-LF becomes just CR -
977 * and without the NUL suffix too. */
978 if (telnet->opt_states[o_we_bin.index] == ACTIVE)
979 telnet->bufsize = sk_write(telnet->s, "\r", 1);
980 else
981 telnet->bufsize = sk_write(telnet->s, "\r\n", 2);
982 break;
983 case TS_SYNCH:
984 b[1] = DM;
985 telnet->bufsize = sk_write(telnet->s, (char *)b, 1);
986 telnet->bufsize = sk_write_oob(telnet->s, (char *)(b + 1), 1);
987 break;
988 case TS_RECHO:
989 if (telnet->opt_states[o_echo.index] == INACTIVE ||
990 telnet->opt_states[o_echo.index] == REALLY_INACTIVE) {
991 telnet->opt_states[o_echo.index] = REQUESTED;
992 send_opt(telnet, o_echo.send, o_echo.option);
993 }
994 break;
995 case TS_LECHO:
996 if (telnet->opt_states[o_echo.index] == ACTIVE) {
997 telnet->opt_states[o_echo.index] = REQUESTED;
998 send_opt(telnet, o_echo.nsend, o_echo.option);
999 }
1000 break;
1001 case TS_PING:
1002 if (telnet->opt_states[o_they_sga.index] == ACTIVE) {
1003 b[1] = NOP;
1004 telnet->bufsize = sk_write(telnet->s, (char *)b, 2);
1005 }
1006 break;
1007 default:
1008 break; /* never heard of it */
1009 }
1010 }
1011
1012 static const struct telnet_special *telnet_get_specials(void *handle)
1013 {
1014 static const struct telnet_special specials[] = {
1015 {"Are You There", TS_AYT},
1016 {"Break", TS_BRK},
1017 {"Synch", TS_SYNCH},
1018 {"Erase Character", TS_EC},
1019 {"Erase Line", TS_EL},
1020 {"Go Ahead", TS_GA},
1021 {"No Operation", TS_NOP},
1022 {NULL, TS_SEP},
1023 {"Abort Process", TS_ABORT},
1024 {"Abort Output", TS_AO},
1025 {"Interrupt Process", TS_IP},
1026 {"Suspend Process", TS_SUSP},
1027 {NULL, TS_SEP},
1028 {"End Of Record", TS_EOR},
1029 {"End Of File", TS_EOF},
1030 {NULL, TS_EXITMENU}
1031 };
1032 return specials;
1033 }
1034
1035 static int telnet_connected(void *handle)
1036 {
1037 Telnet telnet = (Telnet) handle;
1038 return telnet->s != NULL;
1039 }
1040
1041 static int telnet_sendok(void *handle)
1042 {
1043 /* Telnet telnet = (Telnet) handle; */
1044 return 1;
1045 }
1046
1047 static void telnet_unthrottle(void *handle, int backlog)
1048 {
1049 Telnet telnet = (Telnet) handle;
1050 sk_set_frozen(telnet->s, backlog > TELNET_MAX_BACKLOG);
1051 }
1052
1053 static int telnet_ldisc(void *handle, int option)
1054 {
1055 Telnet telnet = (Telnet) handle;
1056 if (option == LD_ECHO)
1057 return telnet->echoing;
1058 if (option == LD_EDIT)
1059 return telnet->editing;
1060 return FALSE;
1061 }
1062
1063 static void telnet_provide_ldisc(void *handle, void *ldisc)
1064 {
1065 Telnet telnet = (Telnet) handle;
1066 telnet->ldisc = ldisc;
1067 }
1068
1069 static void telnet_provide_logctx(void *handle, void *logctx)
1070 {
1071 /* This is a stub. */
1072 }
1073
1074 static int telnet_exitcode(void *handle)
1075 {
1076 Telnet telnet = (Telnet) handle;
1077 if (telnet->s != NULL)
1078 return -1; /* still connected */
1079 else
1080 /* Telnet doesn't transmit exit codes back to the client */
1081 return 0;
1082 }
1083
1084 /*
1085 * cfg_info for Telnet does nothing at all.
1086 */
1087 static int telnet_cfg_info(void *handle)
1088 {
1089 return 0;
1090 }
1091
1092 Backend telnet_backend = {
1093 telnet_init,
1094 telnet_free,
1095 telnet_reconfig,
1096 telnet_send,
1097 telnet_sendbuffer,
1098 telnet_size,
1099 telnet_special,
1100 telnet_get_specials,
1101 telnet_connected,
1102 telnet_exitcode,
1103 telnet_sendok,
1104 telnet_ldisc,
1105 telnet_provide_ldisc,
1106 telnet_provide_logctx,
1107 telnet_unthrottle,
1108 telnet_cfg_info,
1109 23
1110 };
Local modifications for Simon Tatham's `PuTTY' SSH client and terminal emulator