14 static Socket s = NULL;
16 static void *frontend;
17 static int telnet_term_width, telnet_term_height;
19 #define IAC 255 /* interpret as command: */
20 #define DONT 254 /* you are not to use option */
21 #define DO 253 /* please, you use option */
22 #define WONT 252 /* I won't use option */
23 #define WILL 251 /* I will use option */
24 #define SB 250 /* interpret as subnegotiation */
25 #define SE 240 /* end sub negotiation */
27 #define GA 249 /* you may reverse the line */
28 #define EL 248 /* erase the current line */
29 #define EC 247 /* erase the current character */
30 #define AYT 246 /* are you there */
31 #define AO 245 /* abort output--but let prog finish */
32 #define IP 244 /* interrupt process--permanently */
33 #define BREAK 243 /* break */
34 #define DM 242 /* data mark--for connect. cleaning */
35 #define NOP 241 /* nop */
36 #define EOR 239 /* end of record (transparent mode) */
37 #define ABORT 238 /* Abort process */
38 #define SUSP 237 /* Suspend process */
39 #define xEOF 236 /* End of file: EOF is already used... */
41 #define TELOPT_BINARY 0 /* 8-bit data path */
42 #define TELOPT_ECHO 1 /* echo */
43 #define TELOPT_RCP 2 /* prepare to reconnect */
44 #define TELOPT_SGA 3 /* suppress go ahead */
45 #define TELOPT_NAMS 4 /* approximate message size */
46 #define TELOPT_STATUS 5 /* give status */
47 #define TELOPT_TM 6 /* timing mark */
48 #define TELOPT_RCTE 7 /* remote controlled transmission and echo */
49 #define TELOPT_NAOL 8 /* negotiate about output line width */
50 #define TELOPT_NAOP 9 /* negotiate about output page size */
51 #define TELOPT_NAOCRD 10 /* negotiate about CR disposition */
52 #define TELOPT_NAOHTS 11 /* negotiate about horizontal tabstops */
53 #define TELOPT_NAOHTD 12 /* negotiate about horizontal tab disposition */
54 #define TELOPT_NAOFFD 13 /* negotiate about formfeed disposition */
55 #define TELOPT_NAOVTS 14 /* negotiate about vertical tab stops */
56 #define TELOPT_NAOVTD 15 /* negotiate about vertical tab disposition */
57 #define TELOPT_NAOLFD 16 /* negotiate about output LF disposition */
58 #define TELOPT_XASCII 17 /* extended ascic character set */
59 #define TELOPT_LOGOUT 18 /* force logout */
60 #define TELOPT_BM 19 /* byte macro */
61 #define TELOPT_DET 20 /* data entry terminal */
62 #define TELOPT_SUPDUP 21 /* supdup protocol */
63 #define TELOPT_SUPDUPOUTPUT 22 /* supdup output */
64 #define TELOPT_SNDLOC 23 /* send location */
65 #define TELOPT_TTYPE 24 /* terminal type */
66 #define TELOPT_EOR 25 /* end or record */
67 #define TELOPT_TUID 26 /* TACACS user identification */
68 #define TELOPT_OUTMRK 27 /* output marking */
69 #define TELOPT_TTYLOC 28 /* terminal location number */
70 #define TELOPT_3270REGIME 29 /* 3270 regime */
71 #define TELOPT_X3PAD 30 /* X.3 PAD */
72 #define TELOPT_NAWS 31 /* window size */
73 #define TELOPT_TSPEED 32 /* terminal speed */
74 #define TELOPT_LFLOW 33 /* remote flow control */
75 #define TELOPT_LINEMODE 34 /* Linemode option */
76 #define TELOPT_XDISPLOC 35 /* X Display Location */
77 #define TELOPT_OLD_ENVIRON 36 /* Old - Environment variables */
78 #define TELOPT_AUTHENTICATION 37 /* Authenticate */
79 #define TELOPT_ENCRYPT 38 /* Encryption option */
80 #define TELOPT_NEW_ENVIRON 39 /* New - Environment variables */
81 #define TELOPT_EXOPL 255 /* extended-options-list */
83 #define TELQUAL_IS 0 /* option is... */
84 #define TELQUAL_SEND 1 /* send option */
85 #define TELQUAL_INFO 2 /* ENVIRON: informational version of IS */
95 #define iswritable(x) ( (x) != IAC && (x) != CR )
97 static char *telopt(int opt)
99 #define i(x) if (opt == TELOPT_ ## x) return #x;
144 static void telnet_size(int width, int height);
147 int send; /* what we initially send */
148 int nsend; /* -ve send if requested to stop it */
149 int ack, nak; /* +ve and -ve acknowledgements */
150 int option; /* the option code */
152 REQUESTED, ACTIVE, INACTIVE, REALLY_INACTIVE
156 static struct Opt o_naws =
157 { WILL, WONT, DO, DONT, TELOPT_NAWS, REQUESTED };
158 static struct Opt o_tspeed =
159 { WILL, WONT, DO, DONT, TELOPT_TSPEED, REQUESTED };
160 static struct Opt o_ttype =
161 { WILL, WONT, DO, DONT, TELOPT_TTYPE, REQUESTED };
162 static struct Opt o_oenv = { WILL, WONT, DO, DONT, TELOPT_OLD_ENVIRON,
165 static struct Opt o_nenv = { WILL, WONT, DO, DONT, TELOPT_NEW_ENVIRON,
168 static struct Opt o_echo =
169 { DO, DONT, WILL, WONT, TELOPT_ECHO, REQUESTED };
170 static struct Opt o_we_sga =
171 { WILL, WONT, DO, DONT, TELOPT_SGA, REQUESTED };
172 static struct Opt o_they_sga =
173 { DO, DONT, WILL, WONT, TELOPT_SGA, REQUESTED };
175 static struct Opt *opts[] = {
176 &o_naws, &o_tspeed, &o_ttype, &o_oenv, &o_nenv, &o_echo,
177 &o_we_sga, &o_they_sga, NULL
180 #define TELNET_MAX_BACKLOG 4096
182 static int echoing = TRUE, editing = TRUE;
183 static int activated = FALSE;
184 static int telnet_bufsize;
186 static int sb_opt, sb_len;
187 static char *sb_buf = NULL;
188 static int sb_size = 0;
189 #define SB_DELTA 1024
191 static void c_write1(int c)
195 backlog = from_backend(frontend, 0, &cc, 1);
196 sk_set_frozen(s, backlog > TELNET_MAX_BACKLOG);
199 static void log_option(char *sender, int cmd, int option)
202 sprintf(buf, "%s:\t%s %s", sender,
203 (cmd == WILL ? "WILL" : cmd == WONT ? "WONT" :
204 cmd == DO ? "DO" : cmd == DONT ? "DONT" : "<??>"),
209 static void send_opt(int cmd, int option)
216 telnet_bufsize = sk_write(s, b, 3);
217 log_option("client", cmd, option);
220 static void deactivate_option(struct Opt *o)
222 if (o->state == REQUESTED || o->state == ACTIVE)
223 send_opt(o->nsend, o->option);
224 o->state = REALLY_INACTIVE;
228 * Generate side effects of enabling or disabling an option.
230 static void option_side_effects(struct Opt *o, int enabled)
232 if (o->option == TELOPT_ECHO && o->send == DO)
234 else if (o->option == TELOPT_SGA && o->send == DO)
236 ldisc_send(NULL, 0, 0); /* cause ldisc to notice the change */
238 /* Ensure we get the minimum options */
240 if (o_echo.state == INACTIVE) {
241 o_echo.state = REQUESTED;
242 send_opt(o_echo.send, o_echo.option);
244 if (o_we_sga.state == INACTIVE) {
245 o_we_sga.state = REQUESTED;
246 send_opt(o_we_sga.send, o_we_sga.option);
248 if (o_they_sga.state == INACTIVE) {
249 o_they_sga.state = REQUESTED;
250 send_opt(o_they_sga.send, o_they_sga.option);
256 static void activate_option(struct Opt *o)
258 if (o->send == WILL && o->option == TELOPT_NAWS)
259 telnet_size(telnet_term_width, telnet_term_height);
260 if (o->send == WILL &&
261 (o->option == TELOPT_NEW_ENVIRON ||
262 o->option == TELOPT_OLD_ENVIRON)) {
264 * We may only have one kind of ENVIRON going at a time.
265 * This is a hack, but who cares.
267 deactivate_option(o->option ==
268 TELOPT_NEW_ENVIRON ? &o_oenv : &o_nenv);
270 option_side_effects(o, 1);
273 static void refused_option(struct Opt *o)
275 if (o->send == WILL && o->option == TELOPT_NEW_ENVIRON &&
276 o_oenv.state == INACTIVE) {
277 send_opt(WILL, TELOPT_OLD_ENVIRON);
278 o_oenv.state = REQUESTED;
280 option_side_effects(o, 0);
283 static void proc_rec_opt(int cmd, int option)
287 log_option("server", cmd, option);
288 for (o = opts; *o; o++) {
289 if ((*o)->option == option && (*o)->ack == cmd) {
290 switch ((*o)->state) {
292 (*o)->state = ACTIVE;
298 (*o)->state = ACTIVE;
299 send_opt((*o)->send, option);
302 case REALLY_INACTIVE:
303 send_opt((*o)->nsend, option);
307 } else if ((*o)->option == option && (*o)->nak == cmd) {
308 switch ((*o)->state) {
310 (*o)->state = INACTIVE;
314 (*o)->state = INACTIVE;
315 send_opt((*o)->nsend, option);
316 option_side_effects(*o, 0);
319 case REALLY_INACTIVE:
326 * If we reach here, the option was one we weren't prepared to
327 * cope with. So send a negative ack.
329 send_opt((cmd == WILL ? DONT : WONT), option);
332 static void process_subneg(void)
334 unsigned char b[2048], *p, *q;
340 if (sb_len == 1 && sb_buf[0] == TELQUAL_SEND) {
341 char logbuf[sizeof(cfg.termspeed) + 80];
344 b[2] = TELOPT_TSPEED;
346 strcpy(b + 4, cfg.termspeed);
347 n = 4 + strlen(cfg.termspeed);
350 telnet_bufsize = sk_write(s, b, n + 2);
351 logevent("server:\tSB TSPEED SEND");
352 sprintf(logbuf, "client:\tSB TSPEED IS %s", cfg.termspeed);
355 logevent("server:\tSB TSPEED <something weird>");
358 if (sb_len == 1 && sb_buf[0] == TELQUAL_SEND) {
359 char logbuf[sizeof(cfg.termtype) + 80];
364 for (n = 0; cfg.termtype[n]; n++)
365 b[n + 4] = (cfg.termtype[n] >= 'a'
366 && cfg.termtype[n] <=
367 'z' ? cfg.termtype[n] + 'A' -
368 'a' : cfg.termtype[n]);
371 telnet_bufsize = sk_write(s, b, n + 6);
373 logevent("server:\tSB TTYPE SEND");
374 sprintf(logbuf, "client:\tSB TTYPE IS %s", b + 4);
377 logevent("server:\tSB TTYPE <something weird>\r\n");
379 case TELOPT_OLD_ENVIRON:
380 case TELOPT_NEW_ENVIRON:
383 if (p < q && *p == TELQUAL_SEND) {
386 sprintf(logbuf, "server:\tSB %s SEND", telopt(sb_opt));
388 if (sb_opt == TELOPT_OLD_ENVIRON) {
389 if (cfg.rfc_environ) {
397 * Try to guess the sense of VAR and VALUE.
403 } else if (*p == BSD_VAR) {
411 * With NEW_ENVIRON, the sense of VAR and VALUE
425 while (*e && *e != '\t')
447 telnet_bufsize = sk_write(s, b, n);
448 sprintf(logbuf, "client:\tSB %s IS %s", telopt(sb_opt),
449 n == 6 ? "<nothing>" : "<stuff>");
457 TOP_LEVEL, SEENIAC, SEENWILL, SEENWONT, SEENDO, SEENDONT,
458 SEENSB, SUBNEGOT, SUBNEG_IAC, SEENCR
459 } telnet_state = TOP_LEVEL;
461 static void do_telnet_read(char *buf, int len)
465 int c = (unsigned char) *buf++;
467 switch (telnet_state) {
470 if (c == NUL && telnet_state == SEENCR)
471 telnet_state = TOP_LEVEL;
473 telnet_state = SEENIAC;
479 /* I can't get the F***ing winsock to insert the urgent IAC
480 * into the right position! Even with SO_OOBINLINE it gives
481 * it to recv too soon. And of course the DM byte (that
482 * arrives in the same packet!) appears several K later!!
484 * Oh well, we do get the DM in the right place so I'll
485 * just stop hiding on the next 0xf2 and hope for the best.
491 telnet_state = SEENCR;
493 telnet_state = TOP_LEVEL;
498 telnet_state = SEENDO;
500 telnet_state = SEENDONT;
502 telnet_state = SEENWILL;
504 telnet_state = SEENWONT;
506 telnet_state = SEENSB;
509 telnet_state = TOP_LEVEL;
511 /* ignore everything else; print it if it's IAC */
515 telnet_state = TOP_LEVEL;
519 proc_rec_opt(WILL, c);
520 telnet_state = TOP_LEVEL;
523 proc_rec_opt(WONT, c);
524 telnet_state = TOP_LEVEL;
528 telnet_state = TOP_LEVEL;
531 proc_rec_opt(DONT, c);
532 telnet_state = TOP_LEVEL;
537 telnet_state = SUBNEGOT;
541 telnet_state = SUBNEG_IAC;
544 if (sb_len >= sb_size) {
548 srealloc(sb_buf, sb_size) :
555 if (sb_len < sb_size)
556 sb_buf[sb_len++] = c;
557 telnet_state = SUBNEGOT; /* in case we came here by goto */
562 goto subneg_addchar; /* yes, it's a hack, I know, but... */
565 telnet_state = TOP_LEVEL;
572 static int telnet_closing(Plug plug, char *error_msg, int error_code,
580 /* A socket error has occurred. */
582 connection_fatal("%s", error_msg);
583 } /* Otherwise, the remote side closed the connection normally. */
587 static int telnet_receive(Plug plug, int urgent, char *data, int len)
591 do_telnet_read(data, len);
595 static void telnet_sent(Plug plug, int bufsize)
597 telnet_bufsize = bufsize;
601 * Called to set up the Telnet connection.
603 * Returns an error message, or NULL on success.
605 * Also places the canonical host name into `realhost'. It must be
606 * freed by the caller.
608 static char *telnet_init(void *frontend_handle,
609 char *host, int port, char **realhost, int nodelay)
611 static struct plug_function_table fn_table = {
615 }, *fn_table_ptr = &fn_table;
620 frontend = frontend_handle;
621 telnet_term_width = cfg.width;
622 telnet_term_height = cfg.height;
629 sprintf(buf, "Looking up host \"%.170s\"", host);
632 addr = sk_namelookup(host, realhost);
633 if ((err = sk_addr_error(addr)))
637 port = 23; /* default telnet port */
643 char buf[200], addrbuf[100];
644 sk_getaddr(addr, addrbuf, 100);
645 sprintf(buf, "Connecting to %.100s port %d", addrbuf, port);
648 s = new_connection(addr, *realhost, port, 0, 1, nodelay, &fn_table_ptr);
649 if ((err = sk_socket_error(s)))
655 * Initialise option states.
657 if (cfg.passive_telnet) {
660 for (o = opts; *o; o++)
661 if ((*o)->state == REQUESTED)
662 (*o)->state = INACTIVE;
666 for (o = opts; *o; o++)
667 if ((*o)->state == REQUESTED)
668 send_opt((*o)->send, (*o)->option);
673 * Set up SYNCH state.
681 * Called to send data down the Telnet connection.
683 static int telnet_send(char *buf, int len)
686 static unsigned char iac[2] = { IAC, IAC };
687 static unsigned char cr[2] = { CR, NUL };
689 static unsigned char nl[2] = { CR, LF };
696 while (p < buf + len) {
699 while (iswritable((unsigned char) *p) && p < buf + len)
701 telnet_bufsize = sk_write(s, q, p - q);
703 while (p < buf + len && !iswritable((unsigned char) *p)) {
705 sk_write(s, (unsigned char) *p == IAC ? iac : cr, 2);
710 return telnet_bufsize;
714 * Called to query the current socket sendability status.
716 static int telnet_sendbuffer(void)
718 return telnet_bufsize;
722 * Called to set the size of the window from Telnet's POV.
724 static void telnet_size(int width, int height)
729 telnet_term_width = width;
730 telnet_term_height = height;
732 if (s == NULL || o_naws.state != ACTIVE)
737 b[3] = telnet_term_width >> 8;
738 b[4] = telnet_term_width & 0xFF;
739 b[5] = telnet_term_height >> 8;
740 b[6] = telnet_term_height & 0xFF;
743 telnet_bufsize = sk_write(s, b, 9);
744 sprintf(logbuf, "client:\tSB NAWS %d,%d",
745 ((unsigned char) b[3] << 8) + (unsigned char) b[4],
746 ((unsigned char) b[5] << 8) + (unsigned char) b[6]);
751 * Send Telnet special codes.
753 static void telnet_special(Telnet_Special code)
764 telnet_bufsize = sk_write(s, b, 2);
768 telnet_bufsize = sk_write(s, b, 2);
772 telnet_bufsize = sk_write(s, b, 2);
776 telnet_bufsize = sk_write(s, b, 2);
780 telnet_bufsize = sk_write(s, b, 2);
784 telnet_bufsize = sk_write(s, b, 2);
788 telnet_bufsize = sk_write(s, b, 2);
792 telnet_bufsize = sk_write(s, b, 2);
796 telnet_bufsize = sk_write(s, b, 2);
800 telnet_bufsize = sk_write(s, b, 2);
804 telnet_bufsize = sk_write(s, b, 2);
808 telnet_bufsize = sk_write(s, b, 2);
811 telnet_bufsize = sk_write(s, "\r\n", 2);
815 telnet_bufsize = sk_write(s, b, 1);
816 telnet_bufsize = sk_write_oob(s, b + 1, 1);
819 if (o_echo.state == INACTIVE || o_echo.state == REALLY_INACTIVE) {
820 o_echo.state = REQUESTED;
821 send_opt(o_echo.send, o_echo.option);
825 if (o_echo.state == ACTIVE) {
826 o_echo.state = REQUESTED;
827 send_opt(o_echo.nsend, o_echo.option);
831 if (o_they_sga.state == ACTIVE) {
833 telnet_bufsize = sk_write(s, b, 2);
839 static Socket telnet_socket(void)
844 static int telnet_sendok(void)
849 static void telnet_unthrottle(int backlog)
851 sk_set_frozen(s, backlog > TELNET_MAX_BACKLOG);
854 static int telnet_ldisc(int option)
856 if (option == LD_ECHO)
858 if (option == LD_EDIT)
863 static int telnet_exitcode(void)
865 /* Telnet doesn't transmit exit codes back to the client */
869 Backend telnet_backend = {