1 /* vi: set sw=4 ts=4: */
3 * telnet implementation for busybox
5 * Author: Tomi Ollila <too@iki.fi>
6 * Copyright (C) 1994-2000 by Tomi Ollila
8 * Created: Thu Apr 7 13:29:41 1994 too
9 * Last modified: Fri Jun 9 14:34:24 2000 too
11 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
14 * Revision 3.1 1994/04/17 11:31:54 too
16 * Modified 2000/06/13 for inclusion into BusyBox by Erik Andersen <andersen@codepoet.org>
17 * Modified 2001/05/07 to add ability to pass TTYPE to remote host by Jim McQuillan
19 * Modified 2004/02/11 to add ability to pass the USER variable to remote host
20 * by Fernando Silveira <swrh@gmx.net>
24 //usage:#if ENABLE_FEATURE_TELNET_AUTOLOGIN
25 //usage:#define telnet_trivial_usage
26 //usage: "[-a] [-l USER] HOST [PORT]"
27 //usage:#define telnet_full_usage "\n\n"
28 //usage: "Connect to telnet server\n"
29 //usage: "\n -a Automatic login with $USER variable"
30 //usage: "\n -l USER Automatic login as USER"
33 //usage:#define telnet_trivial_usage
34 //usage: "HOST [PORT]"
35 //usage:#define telnet_full_usage "\n\n"
36 //usage: "Connect to telnet server"
39 #include <arpa/telnet.h>
40 #include <netinet/in.h>
44 /* should be in arpa/telnet.h */
45 # define IAC 255 /* interpret as command: */
46 # define DONT 254 /* you are not to use option */
47 # define DO 253 /* please, you use option */
48 # define WONT 252 /* I won't use option */
49 # define WILL 251 /* I will use option */
50 # define SB 250 /* interpret as subnegotiation */
51 # define SE 240 /* end sub negotiation */
52 # define TELOPT_ECHO 1 /* echo */
53 # define TELOPT_SGA 3 /* suppress go ahead */
54 # define TELOPT_TTYPE 24 /* terminal type */
55 # define TELOPT_NAWS 31 /* window size */
59 # define TRACE(x, y) do { if (x) printf y; } while (0)
84 typedef unsigned char byte;
89 int iaclen; /* could even use byte, but it's a loss on x86 */
90 byte telstate; /* telnet negotiation state from network input */
91 byte telwish; /* DO, DONT, WILL, WONT */
95 #if ENABLE_FEATURE_TELNET_TTYPE
98 #if ENABLE_FEATURE_TELNET_AUTOLOGIN
99 const char *autologin;
101 #if ENABLE_FEATURE_AUTOWIDTH
102 unsigned win_width, win_height;
104 /* same buffer used both for network and console read/write */
105 char buf[DATABUFSIZE];
106 /* buffer to handle telnet negotiations */
107 char iacbuf[IACBUFSIZE];
108 struct termios termios_def;
109 struct termios termios_raw;
111 #define G (*(struct globals*)&bb_common_bufsiz1)
112 #define INIT_G() do { \
113 struct G_sizecheck { \
114 char G_sizecheck[sizeof(G) > COMMON_BUFSIZE ? -1 : 1]; \
119 static void rawmode(void);
120 static void cookmode(void);
121 static void do_linemode(void);
122 static void will_charmode(void);
123 static void telopt(byte c);
124 static void subneg(byte c);
126 static void iac_flush(void)
128 full_write(netfd, G.iacbuf, G.iaclen);
132 static void doexit(int ev) NORETURN;
133 static void doexit(int ev)
139 static void con_escape(void)
143 if (bb_got_signal) /* came from line mode... go raw */
146 full_write1_str("\r\nConsole escape. Commands are:\r\n\n"
147 " l go to line mode\r\n"
148 " c go to character mode\r\n"
149 " z suspend telnet\r\n"
150 " e exit telnet\r\n");
152 if (read(STDIN_FILENO, &b, 1) <= 0)
153 doexit(EXIT_FAILURE);
157 if (!bb_got_signal) {
174 doexit(EXIT_SUCCESS);
177 full_write1_str("continuing...\r\n");
185 static void handle_net_output(int len)
187 byte outbuf[2 * DATABUFSIZE];
189 byte *src = (byte*)G.buf;
190 byte *end = src + len;
200 *++dst = c; /* IAC -> IAC IAC */
202 if (c == '\r' || c == '\n') {
203 /* Enter key sends '\r' in raw mode and '\n' in cooked one.
205 * See RFC 1123 3.3.1 Telnet End-of-Line Convention.
206 * Using CR LF instead of other allowed possibilities
207 * like CR NUL - easier to talk to HTTP/SMTP servers.
209 *dst = '\r'; /* Enter -> CR LF */
214 if (dst - outbuf != 0)
215 full_write(netfd, outbuf, dst - outbuf);
218 static void handle_net_input(int len)
223 for (i = 0; i < len; i++) {
226 if (G.telstate == TS_NORMAL) { /* most typical state */
231 else if (c == '\r') {
235 /* No IACs were seen so far, no need to copy
236 * bytes within G.buf: */
240 switch (G.telstate) {
242 /* Prev char was CR. If cur one is NUL, ignore it.
243 * See RFC 1123 section 3.3.1 for discussion of telnet EOL handling.
245 G.telstate = TS_COPY;
248 /* else: fall through - need to handle CR IAC ... properly */
250 case TS_COPY: /* Prev char was ordinary */
251 /* Similar to NORMAL, but in TS_COPY we need to copy bytes */
260 case TS_IAC: /* Prev char was IAC */
261 if (c == IAC) { /* IAC IAC -> one IAC */
263 G.telstate = TS_COPY;
269 G.telstate = TS_SUB1;
278 /* DATA MARK must be added later */
280 G.telstate = TS_COPY;
284 case TS_OPT: /* Prev chars were IAC WILL/WONT/DO/DONT */
286 G.telstate = TS_COPY;
289 case TS_SUB1: /* Subnegotiation */
290 case TS_SUB2: /* Subnegotiation */
291 subneg(c); /* can change G.telstate */
296 if (G.telstate != TS_NORMAL) {
297 /* We had some IACs, or CR */
300 if (G.telstate == TS_COPY) /* we aren't in the middle of IAC */
301 G.telstate = TS_NORMAL;
306 full_write(STDOUT_FILENO, G.buf, len);
309 static void put_iac(int c)
311 G.iacbuf[G.iaclen++] = c;
314 static void put_iac2(byte wwdd, byte c)
316 if (G.iaclen + 3 > IACBUFSIZE)
324 #if ENABLE_FEATURE_TELNET_TTYPE
325 static void put_iac_subopt(byte c, char *str)
327 int len = strlen(str) + 6; // ( 2 + 1 + 1 + strlen + 2 )
329 if (G.iaclen + len > IACBUFSIZE)
345 #if ENABLE_FEATURE_TELNET_AUTOLOGIN
346 static void put_iac_subopt_autologin(void)
348 int len = strlen(G.autologin) + 6; // (2 + 1 + 1 + strlen + 2)
349 const char *p = "USER";
351 if (G.iaclen + len > IACBUFSIZE)
356 put_iac(TELOPT_NEW_ENVIRON);
358 put_iac(NEW_ENV_VAR);
363 put_iac(NEW_ENV_VALUE);
374 #if ENABLE_FEATURE_AUTOWIDTH
375 static void put_iac_naws(byte c, int x, int y)
377 if (G.iaclen + 9 > IACBUFSIZE)
384 /* "... & 0xff" implicitly done below */
395 static void setConMode(void)
397 if (G.telflags & UF_ECHO) {
398 if (G.charmode == CHM_TRY) {
400 printf("\r\nEntering %s mode"
401 "\r\nEscape character is '^%c'.\r\n", "character", ']');
405 if (G.charmode != CHM_OFF) {
406 G.charmode = CHM_OFF;
407 printf("\r\nEntering %s mode"
408 "\r\nEscape character is '^%c'.\r\n", "line", 'C');
414 static void will_charmode(void)
416 G.charmode = CHM_TRY;
417 G.telflags |= (UF_ECHO | UF_SGA);
420 put_iac2(DO, TELOPT_ECHO);
421 put_iac2(DO, TELOPT_SGA);
425 static void do_linemode(void)
427 G.charmode = CHM_TRY;
428 G.telflags &= ~(UF_ECHO | UF_SGA);
431 put_iac2(DONT, TELOPT_ECHO);
432 put_iac2(DONT, TELOPT_SGA);
436 static void to_notsup(char c)
438 if (G.telwish == WILL)
440 else if (G.telwish == DO)
444 static void to_echo(void)
446 /* if server requests ECHO, don't agree */
447 if (G.telwish == DO) {
448 put_iac2(WONT, TELOPT_ECHO);
451 if (G.telwish == DONT)
454 if (G.telflags & UF_ECHO) {
455 if (G.telwish == WILL)
457 } else if (G.telwish == WONT)
460 if (G.charmode != CHM_OFF)
461 G.telflags ^= UF_ECHO;
463 if (G.telflags & UF_ECHO)
464 put_iac2(DO, TELOPT_ECHO);
466 put_iac2(DONT, TELOPT_ECHO);
469 full_write1_str("\r\n"); /* sudden modec */
472 static void to_sga(void)
474 /* daemon always sends will/wont, client do/dont */
476 if (G.telflags & UF_SGA) {
477 if (G.telwish == WILL)
479 } else if (G.telwish == WONT)
482 G.telflags ^= UF_SGA; /* toggle */
483 if (G.telflags & UF_SGA)
484 put_iac2(DO, TELOPT_SGA);
486 put_iac2(DONT, TELOPT_SGA);
489 #if ENABLE_FEATURE_TELNET_TTYPE
490 static void to_ttype(void)
492 /* Tell server we will (or won't) do TTYPE */
494 put_iac2(WILL, TELOPT_TTYPE);
496 put_iac2(WONT, TELOPT_TTYPE);
500 #if ENABLE_FEATURE_TELNET_AUTOLOGIN
501 static void to_new_environ(void)
503 /* Tell server we will (or will not) do AUTOLOGIN */
505 put_iac2(WILL, TELOPT_NEW_ENVIRON);
507 put_iac2(WONT, TELOPT_NEW_ENVIRON);
511 #if ENABLE_FEATURE_AUTOWIDTH
512 static void to_naws(void)
514 /* Tell server we will do NAWS */
515 put_iac2(WILL, TELOPT_NAWS);
519 static void telopt(byte c)
526 #if ENABLE_FEATURE_TELNET_TTYPE
530 #if ENABLE_FEATURE_TELNET_AUTOLOGIN
531 case TELOPT_NEW_ENVIRON:
532 to_new_environ(); break;
534 #if ENABLE_FEATURE_AUTOWIDTH
537 put_iac_naws(c, G.win_width, G.win_height);
546 /* subnegotiation -- ignore all (except TTYPE,NAWS) */
547 static void subneg(byte c)
549 switch (G.telstate) {
552 G.telstate = TS_SUB2;
553 #if ENABLE_FEATURE_TELNET_TTYPE
555 if (c == TELOPT_TTYPE && G.ttype)
556 put_iac_subopt(TELOPT_TTYPE, G.ttype);
558 #if ENABLE_FEATURE_TELNET_AUTOLOGIN
560 if (c == TELOPT_NEW_ENVIRON && G.autologin)
561 put_iac_subopt_autologin();
566 G.telstate = TS_COPY;
569 G.telstate = TS_SUB1;
574 static void rawmode(void)
577 tcsetattr(0, TCSADRAIN, &G.termios_raw);
580 static void cookmode(void)
583 tcsetattr(0, TCSADRAIN, &G.termios_def);
586 int telnet_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
587 int telnet_main(int argc UNUSED_PARAM, char **argv)
592 struct pollfd ufds[2];
596 #if ENABLE_FEATURE_AUTOWIDTH
597 get_terminal_width_height(0, &G.win_width, &G.win_height);
600 #if ENABLE_FEATURE_TELNET_TTYPE
601 G.ttype = getenv("TERM");
604 if (tcgetattr(0, &G.termios_def) >= 0) {
606 G.termios_raw = G.termios_def;
607 cfmakeraw(&G.termios_raw);
610 #if ENABLE_FEATURE_TELNET_AUTOLOGIN
611 if (1 & getopt32(argv, "al:", &G.autologin))
612 G.autologin = getenv("USER");
620 port = bb_lookup_port(*argv ? *argv++ : "telnet", "tcp", 23);
621 if (*argv) /* extra params?? */
624 xmove_fd(create_and_connect_stream_or_die(host, port), netfd);
626 setsockopt(netfd, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1));
628 signal(SIGINT, record_signo);
630 ufds[0].fd = STDIN_FILENO;
631 ufds[0].events = POLLIN;
633 ufds[1].events = POLLIN;
636 if (poll(ufds, 2, -1) < 0) {
637 /* error, ignore and/or log something, bay go to loop */
645 // FIXME: reads can block. Need full bidirectional buffering.
647 if (ufds[0].revents) {
648 len = safe_read(STDIN_FILENO, G.buf, DATABUFSIZE);
650 doexit(EXIT_SUCCESS);
651 TRACE(0, ("Read con: %d\n", len));
652 handle_net_output(len);
655 if (ufds[1].revents) {
656 len = safe_read(netfd, G.buf, DATABUFSIZE);
658 full_write1_str("Connection closed by foreign host\r\n");
659 doexit(EXIT_FAILURE);
661 TRACE(0, ("Read netfd (%d): %d\n", netfd, len));
662 handle_net_input(len);