14 static Socket s = NULL;
16 #define IAC 255 /* interpret as command: */
17 #define DONT 254 /* you are not to use option */
18 #define DO 253 /* please, you use option */
19 #define WONT 252 /* I won't use option */
20 #define WILL 251 /* I will use option */
21 #define SB 250 /* interpret as subnegotiation */
22 #define SE 240 /* end sub negotiation */
24 #define GA 249 /* you may reverse the line */
25 #define EL 248 /* erase the current line */
26 #define EC 247 /* erase the current character */
27 #define AYT 246 /* are you there */
28 #define AO 245 /* abort output--but let prog finish */
29 #define IP 244 /* interrupt process--permanently */
30 #define BREAK 243 /* break */
31 #define DM 242 /* data mark--for connect. cleaning */
32 #define NOP 241 /* nop */
33 #define EOR 239 /* end of record (transparent mode) */
34 #define ABORT 238 /* Abort process */
35 #define SUSP 237 /* Suspend process */
36 #define xEOF 236 /* End of file: EOF is already used... */
38 #define TELOPT_BINARY 0 /* 8-bit data path */
39 #define TELOPT_ECHO 1 /* echo */
40 #define TELOPT_RCP 2 /* prepare to reconnect */
41 #define TELOPT_SGA 3 /* suppress go ahead */
42 #define TELOPT_NAMS 4 /* approximate message size */
43 #define TELOPT_STATUS 5 /* give status */
44 #define TELOPT_TM 6 /* timing mark */
45 #define TELOPT_RCTE 7 /* remote controlled transmission and echo */
46 #define TELOPT_NAOL 8 /* negotiate about output line width */
47 #define TELOPT_NAOP 9 /* negotiate about output page size */
48 #define TELOPT_NAOCRD 10 /* negotiate about CR disposition */
49 #define TELOPT_NAOHTS 11 /* negotiate about horizontal tabstops */
50 #define TELOPT_NAOHTD 12 /* negotiate about horizontal tab disposition */
51 #define TELOPT_NAOFFD 13 /* negotiate about formfeed disposition */
52 #define TELOPT_NAOVTS 14 /* negotiate about vertical tab stops */
53 #define TELOPT_NAOVTD 15 /* negotiate about vertical tab disposition */
54 #define TELOPT_NAOLFD 16 /* negotiate about output LF disposition */
55 #define TELOPT_XASCII 17 /* extended ascic character set */
56 #define TELOPT_LOGOUT 18 /* force logout */
57 #define TELOPT_BM 19 /* byte macro */
58 #define TELOPT_DET 20 /* data entry terminal */
59 #define TELOPT_SUPDUP 21 /* supdup protocol */
60 #define TELOPT_SUPDUPOUTPUT 22 /* supdup output */
61 #define TELOPT_SNDLOC 23 /* send location */
62 #define TELOPT_TTYPE 24 /* terminal type */
63 #define TELOPT_EOR 25 /* end or record */
64 #define TELOPT_TUID 26 /* TACACS user identification */
65 #define TELOPT_OUTMRK 27 /* output marking */
66 #define TELOPT_TTYLOC 28 /* terminal location number */
67 #define TELOPT_3270REGIME 29 /* 3270 regime */
68 #define TELOPT_X3PAD 30 /* X.3 PAD */
69 #define TELOPT_NAWS 31 /* window size */
70 #define TELOPT_TSPEED 32 /* terminal speed */
71 #define TELOPT_LFLOW 33 /* remote flow control */
72 #define TELOPT_LINEMODE 34 /* Linemode option */
73 #define TELOPT_XDISPLOC 35 /* X Display Location */
74 #define TELOPT_OLD_ENVIRON 36 /* Old - Environment variables */
75 #define TELOPT_AUTHENTICATION 37/* Authenticate */
76 #define TELOPT_ENCRYPT 38 /* Encryption option */
77 #define TELOPT_NEW_ENVIRON 39 /* New - Environment variables */
78 #define TELOPT_EXOPL 255 /* extended-options-list */
80 #define TELQUAL_IS 0 /* option is... */
81 #define TELQUAL_SEND 1 /* send option */
82 #define TELQUAL_INFO 2 /* ENVIRON: informational version of IS */
92 #define iswritable(x) ( (x) != IAC && (x) != CR )
94 static char *telopt(int opt) {
95 #define i(x) if (opt == TELOPT_ ## x) return #x;
96 i(BINARY); i(ECHO); i(RCP); i(SGA); i(NAMS); i(STATUS); i(TM); i(RCTE);
97 i(NAOL); i(NAOP); i(NAOCRD); i(NAOHTS); i(NAOHTD); i(NAOFFD); i(NAOVTS);
98 i(NAOVTD); i(NAOLFD); i(XASCII); i(LOGOUT); i(BM); i(DET); i(SUPDUP);
99 i(SUPDUPOUTPUT); i(SNDLOC); i(TTYPE); i(EOR); i(TUID); i(OUTMRK);
100 i(TTYLOC); i(X3PAD); i(NAWS); i(TSPEED); i(LFLOW); i(LINEMODE);
101 i(XDISPLOC); i(OLD_ENVIRON); i(AUTHENTICATION); i(ENCRYPT);
102 i(NEW_ENVIRON); i(EXOPL);
107 static void telnet_size(void);
110 int send; /* what we initially send */
111 int nsend; /* -ve send if requested to stop it */
112 int ack, nak; /* +ve and -ve acknowledgements */
113 int option; /* the option code */
115 REQUESTED, ACTIVE, INACTIVE, REALLY_INACTIVE
119 static struct Opt o_naws = {WILL, WONT, DO, DONT, TELOPT_NAWS, REQUESTED};
120 static struct Opt o_tspeed = {WILL, WONT, DO, DONT, TELOPT_TSPEED, REQUESTED};
121 static struct Opt o_ttype = {WILL, WONT, DO, DONT, TELOPT_TTYPE, REQUESTED};
122 static struct Opt o_oenv = {WILL, WONT, DO, DONT, TELOPT_OLD_ENVIRON,
124 static struct Opt o_nenv = {WILL, WONT, DO, DONT, TELOPT_NEW_ENVIRON,
126 static struct Opt o_echo = {DO, DONT, WILL, WONT, TELOPT_ECHO, REQUESTED};
127 static struct Opt o_we_sga = {WILL, WONT, DO, DONT, TELOPT_SGA, REQUESTED};
128 static struct Opt o_they_sga = {DO, DONT, WILL, WONT, TELOPT_SGA, REQUESTED};
130 static struct Opt *opts[] = {
131 &o_naws, &o_tspeed, &o_ttype, &o_oenv, &o_nenv, &o_echo,
132 &o_we_sga, &o_they_sga, NULL
136 static int sb_opt, sb_len;
137 static char *sb_buf = NULL;
138 static int sb_size = 0;
139 #define SB_DELTA 1024
141 static void c_write1(int c) {
143 from_backend(0, &cc, 1);
146 static void log_option (char *sender, int cmd, int option) {
148 sprintf(buf, "%s:\t%s %s", sender,
149 (cmd == WILL ? "WILL" : cmd == WONT ? "WONT" :
150 cmd == DO ? "DO" : cmd == DONT ? "DONT" : "<??>"),
155 static void send_opt (int cmd, int option) {
158 b[0] = IAC; b[1] = cmd; b[2] = option;
160 log_option("client", cmd, option);
163 static void deactivate_option (struct Opt *o) {
164 if (o->state == REQUESTED || o->state == ACTIVE)
165 send_opt (o->nsend, o->option);
166 o->state = REALLY_INACTIVE;
169 static void activate_option (struct Opt *o) {
170 if (o->send == WILL && o->option == TELOPT_NAWS)
172 if (o->send == WILL &&
173 (o->option == TELOPT_NEW_ENVIRON ||
174 o->option == TELOPT_OLD_ENVIRON)) {
176 * We may only have one kind of ENVIRON going at a time.
177 * This is a hack, but who cares.
179 deactivate_option (o->option==TELOPT_NEW_ENVIRON ? &o_oenv : &o_nenv);
181 if (o->option == TELOPT_ECHO && cfg.ldisc_term)
182 ldisc = &ldisc_simple;
185 static void refused_option (struct Opt *o) {
186 if (o->send == WILL && o->option == TELOPT_NEW_ENVIRON &&
187 o_oenv.state == INACTIVE) {
188 send_opt (WILL, TELOPT_OLD_ENVIRON);
189 o_oenv.state = REQUESTED;
191 if (o->option == TELOPT_ECHO && cfg.ldisc_term)
195 static void proc_rec_opt (int cmd, int option) {
198 log_option ("server", cmd, option);
199 for (o = opts; *o; o++) {
200 if ((*o)->option == option && (*o)->ack == cmd) {
201 switch ((*o)->state) {
203 (*o)->state = ACTIVE;
204 activate_option (*o);
209 (*o)->state = ACTIVE;
210 send_opt ((*o)->send, option);
211 activate_option (*o);
213 case REALLY_INACTIVE:
214 send_opt ((*o)->nsend, option);
218 } else if ((*o)->option == option && (*o)->nak == cmd) {
219 switch ((*o)->state) {
221 (*o)->state = INACTIVE;
225 (*o)->state = INACTIVE;
226 send_opt ((*o)->nsend, option);
229 case REALLY_INACTIVE:
236 * If we reach here, the option was one we weren't prepared to
237 * cope with. So send a negative ack.
239 send_opt ((cmd == WILL ? DONT : WONT), option);
242 static void process_subneg (void) {
243 unsigned char b[2048], *p, *q;
249 if (sb_len == 1 && sb_buf[0] == TELQUAL_SEND) {
250 char logbuf[sizeof(cfg.termspeed)+80];
251 b[0] = IAC; b[1] = SB; b[2] = TELOPT_TSPEED;
253 strcpy(b+4, cfg.termspeed);
254 n = 4 + strlen(cfg.termspeed);
255 b[n] = IAC; b[n+1] = SE;
257 logevent("server:\tSB TSPEED SEND");
258 sprintf(logbuf, "client:\tSB TSPEED IS %s", cfg.termspeed);
261 logevent ("server:\tSB TSPEED <something weird>");
264 if (sb_len == 1 && sb_buf[0] == TELQUAL_SEND) {
265 char logbuf[sizeof(cfg.termtype)+80];
266 b[0] = IAC; b[1] = SB; b[2] = TELOPT_TTYPE;
268 for (n = 0; cfg.termtype[n]; n++)
269 b[n+4] = (cfg.termtype[n] >= 'a' && cfg.termtype[n] <= 'z' ?
270 cfg.termtype[n] + 'A'-'a' : cfg.termtype[n]);
271 b[n+4] = IAC; b[n+5] = SE;
274 logevent("server:\tSB TTYPE SEND");
275 sprintf(logbuf, "client:\tSB TTYPE IS %s", b+4);
278 logevent("server:\tSB TTYPE <something weird>\r\n");
280 case TELOPT_OLD_ENVIRON:
281 case TELOPT_NEW_ENVIRON:
284 if (p < q && *p == TELQUAL_SEND) {
287 sprintf (logbuf, "server:\tSB %s SEND", telopt(sb_opt));
289 if (sb_opt == TELOPT_OLD_ENVIRON) {
290 if (cfg.rfc_environ) {
298 * Try to guess the sense of VAR and VALUE.
304 } else if (*p == BSD_VAR) {
312 * With NEW_ENVIRON, the sense of VAR and VALUE
318 b[0] = IAC; b[1] = SB; b[2] = sb_opt;
324 while (*e && *e != '\t') b[n++] = *e++;
327 while (*e) b[n++] = *e++;
331 b[n++] = var; b[n++] = 'U'; b[n++] = 'S';
332 b[n++] = 'E'; b[n++] = 'R'; b[n++] = value;
334 while (*e) b[n++] = *e++;
336 b[n++] = IAC; b[n++] = SE;
338 sprintf(logbuf, "client:\tSB %s IS %s", telopt(sb_opt),
339 n==6 ? "<nothing>" : "<stuff>");
347 TOPLEVEL, SEENIAC, SEENWILL, SEENWONT, SEENDO, SEENDONT,
348 SEENSB, SUBNEGOT, SUBNEG_IAC, SEENCR
349 } telnet_state = TOPLEVEL;
351 static void do_telnet_read (char *buf, int len) {
354 int c = (unsigned char) *buf++;
356 switch (telnet_state) {
359 if (c == NUL && telnet_state == SEENCR)
360 telnet_state = TOPLEVEL;
362 telnet_state = SEENIAC;
368 /* I can't get the F***ing winsock to insert the urgent IAC
369 * into the right position! Even with SO_OOBINLINE it gives
370 * it to recv too soon. And of course the DM byte (that
371 * arrives in the same packet!) appears several K later!!
373 * Oh well, we do get the DM in the right place so I'll
374 * just stop hiding on the next 0xf2 and hope for the best.
376 else if (c == DM) in_synch = 0;
379 telnet_state = SEENCR;
381 telnet_state = TOPLEVEL;
385 if (c == DO) telnet_state = SEENDO;
386 else if (c == DONT) telnet_state = SEENDONT;
387 else if (c == WILL) telnet_state = SEENWILL;
388 else if (c == WONT) telnet_state = SEENWONT;
389 else if (c == SB) telnet_state = SEENSB;
392 telnet_state = TOPLEVEL;
395 /* ignore everything else; print it if it's IAC */
399 telnet_state = TOPLEVEL;
403 proc_rec_opt (WILL, c);
404 telnet_state = TOPLEVEL;
407 proc_rec_opt (WONT, c);
408 telnet_state = TOPLEVEL;
411 proc_rec_opt (DO, c);
412 telnet_state = TOPLEVEL;
415 proc_rec_opt (DONT, c);
416 telnet_state = TOPLEVEL;
421 telnet_state = SUBNEGOT;
425 telnet_state = SUBNEG_IAC;
428 if (sb_len >= sb_size) {
432 srealloc(sb_buf, sb_size) :
439 if (sb_len < sb_size)
440 sb_buf[sb_len++] = c;
441 telnet_state = SUBNEGOT;/* in case we came here by goto */
446 goto subneg_addchar; /* yes, it's a hack, I know, but... */
449 telnet_state = TOPLEVEL;
456 static int telnet_receive(Socket s, int urgent, char *data, int len) {
458 /* Connection has closed. */
463 do_telnet_read (data, len);
468 * Called to set up the Telnet connection.
470 * Returns an error message, or NULL on success.
472 * Also places the canonical host name into `realhost'.
474 static char *telnet_init (char *host, int port, char **realhost) {
481 addr = sk_namelookup(host, realhost);
482 if ( (err = sk_addr_error(addr)) )
486 port = 23; /* default telnet port */
491 s = sk_new(addr, port, telnet_receive);
492 if ( (err = sk_socket_error(s)) )
498 * Initialise option states.
504 for (o = opts; *o; o++)
505 if ((*o)->state == REQUESTED)
506 (*o)->state = INACTIVE;
512 for (o = opts; *o; o++)
513 if ((*o)->state == REQUESTED)
514 send_opt ((*o)->send, (*o)->option);
518 * Set up SYNCH state.
523 * We have no pre-session phase.
531 * Called to send data down the Telnet connection.
533 static void telnet_send (char *buf, int len) {
535 static unsigned char iac[2] = { IAC, IAC };
536 static unsigned char cr[2] = { CR, NUL };
537 static unsigned char nl[2] = { CR, LF };
543 while (p < buf+len) {
546 while (iswritable((unsigned char)*p) && p < buf+len) p++;
549 while (p < buf+len && !iswritable((unsigned char)*p)) {
550 sk_write(s, (unsigned char)*p == IAC ? iac : nl, 2);
557 * Called to set the size of the window from Telnet's POV.
559 static void telnet_size(void) {
563 if (s == NULL || o_naws.state != ACTIVE)
565 b[0] = IAC; b[1] = SB; b[2] = TELOPT_NAWS;
566 b[3] = cols >> 8; b[4] = cols & 0xFF;
567 b[5] = rows >> 8; b[6] = rows & 0xFF;
568 b[7] = IAC; b[8] = SE;
570 sprintf(logbuf, "client:\tSB NAWS %d,%d",
571 ((unsigned char)b[3] << 8) + (unsigned char)b[4],
572 ((unsigned char)b[5] << 8) + (unsigned char)b[6]);
577 * Send Telnet special codes.
579 static void telnet_special (Telnet_Special code) {
587 case TS_AYT: b[1] = AYT; sk_write(s, b, 2); break;
588 case TS_BRK: b[1] = BREAK; sk_write(s, b, 2); break;
589 case TS_EC: b[1] = EC; sk_write(s, b, 2); break;
590 case TS_EL: b[1] = EL; sk_write(s, b, 2); break;
591 case TS_GA: b[1] = GA; sk_write(s, b, 2); break;
592 case TS_NOP: b[1] = NOP; sk_write(s, b, 2); break;
593 case TS_ABORT: b[1] = ABORT; sk_write(s, b, 2); break;
594 case TS_AO: b[1] = AO; sk_write(s, b, 2); break;
595 case TS_IP: b[1] = IP; sk_write(s, b, 2); break;
596 case TS_SUSP: b[1] = SUSP; sk_write(s, b, 2); break;
597 case TS_EOR: b[1] = EOR; sk_write(s, b, 2); break;
598 case TS_EOF: b[1] = xEOF; sk_write(s, b, 2); break;
602 sk_write_oob (s, b+1, 1);
605 if (o_echo.state == INACTIVE || o_echo.state == REALLY_INACTIVE) {
606 o_echo.state = REQUESTED;
607 send_opt (o_echo.send, o_echo.option);
611 if (o_echo.state == ACTIVE) {
612 o_echo.state = REQUESTED;
613 send_opt (o_echo.nsend, o_echo.option);
617 if (o_they_sga.state == ACTIVE) {
625 static Socket telnet_socket(void) { return s; }
627 static int telnet_sendok(void) { return 1; }
629 Backend telnet_backend = {