2 * Simple Telnet server code, adapted from PuTTY's own Telnet
3 * client code for use as a Cygwin local pty proxy.
22 #define IAC 255 /* interpret as command: */
23 #define DONT 254 /* you are not to use option */
24 #define DO 253 /* please, you use option */
25 #define WONT 252 /* I won't use option */
26 #define WILL 251 /* I will use option */
27 #define SB 250 /* interpret as subnegotiation */
28 #define SE 240 /* end sub negotiation */
30 #define GA 249 /* you may reverse the line */
31 #define EL 248 /* erase the current line */
32 #define EC 247 /* erase the current character */
33 #define AYT 246 /* are you there */
34 #define AO 245 /* abort output--but let prog finish */
35 #define IP 244 /* interrupt process--permanently */
36 #define BREAK 243 /* break */
37 #define DM 242 /* data mark--for connect. cleaning */
38 #define NOP 241 /* nop */
39 #define EOR 239 /* end of record (transparent mode) */
40 #define ABORT 238 /* Abort process */
41 #define SUSP 237 /* Suspend process */
42 #define xEOF 236 /* End of file: EOF is already used... */
45 X(BINARY, 0) /* 8-bit data path */ \
46 X(ECHO, 1) /* echo */ \
47 X(RCP, 2) /* prepare to reconnect */ \
48 X(SGA, 3) /* suppress go ahead */ \
49 X(NAMS, 4) /* approximate message size */ \
50 X(STATUS, 5) /* give status */ \
51 X(TM, 6) /* timing mark */ \
52 X(RCTE, 7) /* remote controlled transmission and echo */ \
53 X(NAOL, 8) /* negotiate about output line width */ \
54 X(NAOP, 9) /* negotiate about output page size */ \
55 X(NAOCRD, 10) /* negotiate about CR disposition */ \
56 X(NAOHTS, 11) /* negotiate about horizontal tabstops */ \
57 X(NAOHTD, 12) /* negotiate about horizontal tab disposition */ \
58 X(NAOFFD, 13) /* negotiate about formfeed disposition */ \
59 X(NAOVTS, 14) /* negotiate about vertical tab stops */ \
60 X(NAOVTD, 15) /* negotiate about vertical tab disposition */ \
61 X(NAOLFD, 16) /* negotiate about output LF disposition */ \
62 X(XASCII, 17) /* extended ascic character set */ \
63 X(LOGOUT, 18) /* force logout */ \
64 X(BM, 19) /* byte macro */ \
65 X(DET, 20) /* data entry terminal */ \
66 X(SUPDUP, 21) /* supdup protocol */ \
67 X(SUPDUPOUTPUT, 22) /* supdup output */ \
68 X(SNDLOC, 23) /* send location */ \
69 X(TTYPE, 24) /* terminal type */ \
70 X(EOR, 25) /* end or record */ \
71 X(TUID, 26) /* TACACS user identification */ \
72 X(OUTMRK, 27) /* output marking */ \
73 X(TTYLOC, 28) /* terminal location number */ \
74 X(3270REGIME, 29) /* 3270 regime */ \
75 X(X3PAD, 30) /* X.3 PAD */ \
76 X(NAWS, 31) /* window size */ \
77 X(TSPEED, 32) /* terminal speed */ \
78 X(LFLOW, 33) /* remote flow control */ \
79 X(LINEMODE, 34) /* Linemode option */ \
80 X(XDISPLOC, 35) /* X Display Location */ \
81 X(OLD_ENVIRON, 36) /* Old - Environment variables */ \
82 X(AUTHENTICATION, 37) /* Authenticate */ \
83 X(ENCRYPT, 38) /* Encryption option */ \
84 X(NEW_ENVIRON, 39) /* New - Environment variables */ \
85 X(TN3270E, 40) /* TN3270 enhancements */ \
87 X(CHARSET, 42) /* Character set */ \
88 X(RSP, 43) /* Remote serial port */ \
89 X(COM_PORT_OPTION, 44) /* Com port control */ \
90 X(SLE, 45) /* Suppress local echo */ \
91 X(STARTTLS, 46) /* Start TLS */ \
92 X(KERMIT, 47) /* Automatic Kermit file transfer */ \
95 X(PRAGMA_LOGON, 138) \
97 X(PRAGMA_HEARTBEAT, 140) \
98 X(EXOPL, 255) /* extended-options-list */
100 #define telnet_enum(x,y) TELOPT_##x = y,
101 enum { TELOPTS(telnet_enum) dummy=0 };
104 #define TELQUAL_IS 0 /* option is... */
105 #define TELQUAL_SEND 1 /* send option */
106 #define TELQUAL_INFO 2 /* ENVIRON: informational version of IS */
116 #define iswritable(x) ( (x) != IAC && (x) != CR )
118 static char *telopt(int opt)
120 #define telnet_str(x,y) case TELOPT_##x: return #x;
129 static void telnet_size(void *handle, int width, int height);
132 int send; /* what we initially send */
133 int nsend; /* -ve send if requested to stop it */
134 int ack, nak; /* +ve and -ve acknowledgements */
135 int option; /* the option code */
136 int index; /* index into telnet->opt_states[] */
138 REQUESTED, ACTIVE, INACTIVE, REALLY_INACTIVE
156 static const struct Opt o_naws =
157 { DO, DONT, WILL, WONT, TELOPT_NAWS, OPTINDEX_NAWS, REQUESTED };
158 static const struct Opt o_ttype =
159 { DO, DONT, WILL, WONT, TELOPT_TTYPE, OPTINDEX_TTYPE, REQUESTED };
160 static const struct Opt o_oenv =
161 { DO, DONT, WILL, WONT, TELOPT_OLD_ENVIRON, OPTINDEX_OENV, INACTIVE };
162 static const struct Opt o_nenv =
163 { DO, DONT, WILL, WONT, TELOPT_NEW_ENVIRON, OPTINDEX_NENV, REQUESTED };
164 static const struct Opt o_echo =
165 { WILL, WONT, DO, DONT, TELOPT_ECHO, OPTINDEX_ECHO, REQUESTED };
166 static const struct Opt o_they_sga =
167 { DO, DONT, WILL, WONT, TELOPT_SGA, OPTINDEX_WE_SGA, REQUESTED };
168 static const struct Opt o_we_sga =
169 { WILL, WONT, DO, DONT, TELOPT_SGA, OPTINDEX_THEY_SGA, REQUESTED };
171 static const struct Opt *const opts[] = {
172 &o_echo, &o_we_sga, &o_they_sga, &o_naws, &o_ttype, &o_oenv, &o_nenv, NULL
176 int opt_states[NUM_OPTS];
179 unsigned char *sb_buf;
183 TOP_LEVEL, SEENIAC, SEENWILL, SEENWONT, SEENDO, SEENDONT,
184 SEENSB, SUBNEGOT, SUBNEG_IAC, SEENCR
190 * Options we must finish processing before launching the shell
192 int old_environ_done, new_environ_done, ttype_done;
195 * Ready to start shell?
199 struct shell_data shdata;
202 #define TELNET_MAX_BACKLOG 4096
204 #define SB_DELTA 1024
206 static void send_opt(Telnet telnet, int cmd, int option)
213 sel_write(telnet->net, (char *)b, 3);
216 static void deactivate_option(Telnet telnet, const struct Opt *o)
218 if (telnet->opt_states[o->index] == REQUESTED ||
219 telnet->opt_states[o->index] == ACTIVE)
220 send_opt(telnet, o->nsend, o->option);
221 telnet->opt_states[o->index] = REALLY_INACTIVE;
225 * Generate side effects of enabling or disabling an option.
227 static void option_side_effects(Telnet telnet, const struct Opt *o, int enabled)
231 static void activate_option(Telnet telnet, const struct Opt *o)
233 if (o->option == TELOPT_NEW_ENVIRON ||
234 o->option == TELOPT_OLD_ENVIRON ||
235 o->option == TELOPT_TTYPE) {
240 buf[3] = TELQUAL_SEND;
243 sel_write(telnet->net, buf, 6);
245 option_side_effects(telnet, o, 1);
248 static void done_option(Telnet telnet, int option)
250 if (option == TELOPT_OLD_ENVIRON)
251 telnet->old_environ_done = 1;
252 else if (option == TELOPT_NEW_ENVIRON)
253 telnet->new_environ_done = 1;
254 else if (option == TELOPT_TTYPE)
255 telnet->ttype_done = 1;
257 if (telnet->old_environ_done && telnet->new_environ_done &&
258 telnet->ttype_done) {
259 telnet->shell_ok = 1;
263 static void refused_option(Telnet telnet, const struct Opt *o)
265 done_option(telnet, o->option);
266 if (o->send == WILL && o->option == TELOPT_NEW_ENVIRON &&
267 telnet->opt_states[o_oenv.index] == INACTIVE) {
268 send_opt(telnet, WILL, TELOPT_OLD_ENVIRON);
269 telnet->opt_states[o_oenv.index] = REQUESTED;
270 telnet->old_environ_done = 0;
272 option_side_effects(telnet, o, 0);
275 static void proc_rec_opt(Telnet telnet, int cmd, int option)
277 const struct Opt *const *o;
279 for (o = opts; *o; o++) {
280 if ((*o)->option == option && (*o)->ack == cmd) {
281 switch (telnet->opt_states[(*o)->index]) {
283 telnet->opt_states[(*o)->index] = ACTIVE;
284 activate_option(telnet, *o);
289 telnet->opt_states[(*o)->index] = ACTIVE;
290 send_opt(telnet, (*o)->send, option);
291 activate_option(telnet, *o);
293 case REALLY_INACTIVE:
294 send_opt(telnet, (*o)->nsend, option);
298 } else if ((*o)->option == option && (*o)->nak == cmd) {
299 switch (telnet->opt_states[(*o)->index]) {
301 telnet->opt_states[(*o)->index] = INACTIVE;
302 refused_option(telnet, *o);
305 telnet->opt_states[(*o)->index] = INACTIVE;
306 send_opt(telnet, (*o)->nsend, option);
307 option_side_effects(telnet, *o, 0);
310 case REALLY_INACTIVE:
317 * If we reach here, the option was one we weren't prepared to
318 * cope with. If the request was positive (WILL or DO), we send
319 * a negative ack to indicate refusal. If the request was
320 * negative (WONT / DONT), we must do nothing.
322 if (cmd == WILL || cmd == DO)
323 send_opt(telnet, (cmd == WILL ? DONT : WONT), option);
326 static void process_subneg(Telnet telnet)
328 unsigned char b[2048], *p, *q;
332 switch (telnet->sb_opt) {
333 case TELOPT_OLD_ENVIRON:
334 case TELOPT_NEW_ENVIRON:
335 if (telnet->sb_buf[0] == TELQUAL_IS) {
336 if (telnet->sb_opt == TELOPT_NEW_ENVIRON) {
340 if (telnet->sb_len > 1 && !(telnet->sb_buf[0] &~ 1)) {
341 var = telnet->sb_buf[0];
342 value = BSD_VAR ^ BSD_VALUE ^ var;
350 while (n < telnet->sb_len && telnet->sb_buf[n] == var) {
351 int varpos, varlen, valpos, vallen;
355 while (n < telnet->sb_len && telnet->sb_buf[n] != value)
357 if (n == telnet->sb_len)
361 while (n < telnet->sb_len && telnet->sb_buf[n] != var)
365 result = snewn(varlen + vallen + 2, char);
366 sprintf(result, "%.*s=%.*s",
367 varlen, telnet->sb_buf+varpos,
368 vallen, telnet->sb_buf+valpos);
369 if (telnet->shdata.nenvvars >= telnet->envvarsize) {
370 telnet->envvarsize = telnet->shdata.nenvvars * 3 / 2 + 16;
371 telnet->shdata.envvars = sresize(telnet->shdata.envvars,
372 telnet->envvarsize, char *);
374 telnet->shdata.envvars[telnet->shdata.nenvvars++] = result;
376 done_option(telnet, telnet->sb_opt);
379 if (telnet->sb_len >= 1 && telnet->sb_buf[0] == TELQUAL_IS) {
380 telnet->shdata.termtype = snewn(5 + telnet->sb_len, char);
381 strcpy(telnet->shdata.termtype, "TERM=");
382 for (n = 0; n < telnet->sb_len-1; n++) {
383 char c = telnet->sb_buf[n+1];
384 if (c >= 'A' && c <= 'Z')
386 telnet->shdata.termtype[n+5] = c;
388 telnet->shdata.termtype[telnet->sb_len+5-1] = '\0';
390 done_option(telnet, telnet->sb_opt);
393 if (telnet->sb_len == 4) {
395 w = (unsigned char)telnet->sb_buf[0];
396 w = (w << 8) | (unsigned char)telnet->sb_buf[1];
397 h = (unsigned char)telnet->sb_buf[2];
398 h = (h << 8) | (unsigned char)telnet->sb_buf[3];
405 void telnet_from_net(Telnet telnet, char *buf, int len)
408 int c = (unsigned char) *buf++;
410 switch (telnet->state) {
414 * PuTTY sends Telnet's new line sequence (CR LF on
415 * the wire) in response to the return key. We must
416 * therefore treat that as equivalent to CR NUL, and
417 * send CR to the pty.
419 if ((c == NUL || c == '\n') && telnet->state == SEENCR)
420 telnet->state = TOP_LEVEL;
422 telnet->state = SEENIAC;
425 sel_write(telnet->pty, &cc, 1);
428 telnet->state = SEENCR;
430 telnet->state = TOP_LEVEL;
435 telnet->state = SEENDO;
437 telnet->state = SEENDONT;
439 telnet->state = SEENWILL;
441 telnet->state = SEENWONT;
443 telnet->state = SEENSB;
445 telnet->state = TOP_LEVEL;
447 /* ignore everything else; print it if it's IAC */
450 sel_write(telnet->pty, &cc, 1);
452 telnet->state = TOP_LEVEL;
456 proc_rec_opt(telnet, WILL, c);
457 telnet->state = TOP_LEVEL;
460 proc_rec_opt(telnet, WONT, c);
461 telnet->state = TOP_LEVEL;
464 proc_rec_opt(telnet, DO, c);
465 telnet->state = TOP_LEVEL;
468 proc_rec_opt(telnet, DONT, c);
469 telnet->state = TOP_LEVEL;
474 telnet->state = SUBNEGOT;
478 telnet->state = SUBNEG_IAC;
481 if (telnet->sb_len >= telnet->sb_size) {
482 telnet->sb_size += SB_DELTA;
483 telnet->sb_buf = sresize(telnet->sb_buf, telnet->sb_size,
486 telnet->sb_buf[telnet->sb_len++] = c;
487 telnet->state = SUBNEGOT; /* in case we came here by goto */
492 goto subneg_addchar; /* yes, it's a hack, I know, but... */
494 process_subneg(telnet);
495 telnet->state = TOP_LEVEL;
502 Telnet telnet_new(sel_wfd *net, sel_wfd *pty)
506 telnet = snew(struct telnet_tag);
507 telnet->sb_buf = NULL;
509 telnet->state = TOP_LEVEL;
512 telnet->shdata.envvars = NULL;
513 telnet->shdata.nenvvars = telnet->envvarsize = 0;
514 telnet->shdata.termtype = NULL;
517 * Initialise option states.
520 const struct Opt *const *o;
522 for (o = opts; *o; o++) {
523 telnet->opt_states[(*o)->index] = (*o)->initial_state;
524 if (telnet->opt_states[(*o)->index] == REQUESTED)
525 send_opt(telnet, (*o)->send, (*o)->option);
529 telnet->old_environ_done = 1; /* initially don't want to bother */
530 telnet->new_environ_done = 0;
531 telnet->ttype_done = 0;
532 telnet->shell_ok = 0;
537 void telnet_free(Telnet telnet)
539 sfree(telnet->sb_buf);
543 void telnet_from_pty(Telnet telnet, char *buf, int len)
545 unsigned char *p, *end;
546 static const unsigned char iac[2] = { IAC, IAC };
547 static const unsigned char cr[2] = { CR, NUL };
549 static const unsigned char nl[2] = { CR, LF };
552 p = (unsigned char *)buf;
553 end = (unsigned char *)(buf + len);
555 unsigned char *q = p;
557 while (p < end && iswritable(*p))
559 sel_write(telnet->net, (char *)q, p - q);
561 while (p < end && !iswritable(*p)) {
562 sel_write(telnet->net, (char *)(*p == IAC ? iac : cr), 2);
568 int telnet_shell_ok(Telnet telnet, struct shell_data *shdata)
570 if (telnet->shell_ok)
571 *shdata = telnet->shdata; /* structure copy */
572 return telnet->shell_ok;