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 #include <arpa/telnet.h>
25 #include <netinet/in.h>
29 #define TRACE(x, y) do { if (x) printf y; } while (0)
54 typedef unsigned char byte;
59 int iaclen; /* could even use byte, but it's a loss on x86 */
60 byte telstate; /* telnet negotiation state from network input */
61 byte telwish; /* DO, DONT, WILL, WONT */
65 #if ENABLE_FEATURE_TELNET_TTYPE
68 #if ENABLE_FEATURE_TELNET_AUTOLOGIN
69 const char *autologin;
71 #if ENABLE_FEATURE_AUTOWIDTH
72 unsigned win_width, win_height;
74 /* same buffer used both for network and console read/write */
75 char buf[DATABUFSIZE];
76 /* buffer to handle telnet negotiations */
77 char iacbuf[IACBUFSIZE];
78 struct termios termios_def;
79 struct termios termios_raw;
81 #define G (*(struct globals*)&bb_common_bufsiz1)
82 #define INIT_G() do { \
83 struct G_sizecheck { \
84 char G_sizecheck[sizeof(G) > COMMON_BUFSIZE ? -1 : 1]; \
89 static void rawmode(void);
90 static void cookmode(void);
91 static void do_linemode(void);
92 static void will_charmode(void);
93 static void telopt(byte c);
94 static void subneg(byte c);
96 static void iac_flush(void)
98 write(netfd, G.iacbuf, G.iaclen);
102 #define write_str(fd, str) write(fd, str, sizeof(str) - 1)
104 static void doexit(int ev) NORETURN;
105 static void doexit(int ev)
111 static void con_escape(void)
115 if (bb_got_signal) /* came from line mode... go raw */
118 write_str(1, "\r\nConsole escape. Commands are:\r\n\n"
119 " l go to line mode\r\n"
120 " c go to character mode\r\n"
121 " z suspend telnet\r\n"
122 " e exit telnet\r\n");
124 if (read(STDIN_FILENO, &b, 1) <= 0)
125 doexit(EXIT_FAILURE);
129 if (!bb_got_signal) {
146 doexit(EXIT_SUCCESS);
149 write_str(1, "continuing...\r\n");
157 static void handle_net_output(int len)
159 /* here we could do smart tricks how to handle 0xFF:s in output
160 * stream like writing twice every sequence of FF:s (thus doing
161 * many write()s. But I think interactive telnet application does
162 * not need to be 100% 8-bit clean, so changing every 0xff:s to
165 * 2002-mar-21, Przemyslaw Czerpak (druzus@polbox.com)
167 * first - I cannot use programs like sz/rz
168 * second - the 0x0D is sent as one character and if the next
169 * char is 0x0A then it's eaten by a server side.
170 * third - why do you have to make 'many write()s'?
171 * I don't understand.
172 * So I implemented it. It's really useful for me. I hope that
173 * other people will find it interesting too.
175 byte outbuf[2 * DATABUFSIZE];
176 byte *p = (byte*)G.buf;
179 for (; len > 0; len--, p++) {
187 outbuf[j++] = c; /* IAC -> IAC IAC */
189 outbuf[j++] = '\0'; /* CR -> CR NUL */
192 full_write(netfd, outbuf, j);
195 static void handle_net_input(int len)
200 for (i = 0; i < len; i++) {
203 if (G.telstate == TS_NORMAL) { /* most typical state */
208 else if (c == '\r') {
212 /* No IACs were seen so far, no need to copy
213 * bytes within G.buf: */
217 switch (G.telstate) {
219 /* Prev char was CR. If cur one is NUL, ignore it.
220 * See RFC 1123 section 3.3.1 for discussion of telnet EOL handling.
222 G.telstate = TS_COPY;
225 /* else: fall through - need to handle CR IAC ... properly */
227 case TS_COPY: /* Prev char was ordinary */
228 /* Similar to NORMAL, but in TS_COPY we need to copy bytes */
237 case TS_IAC: /* Prev char was IAC */
238 if (c == IAC) { /* IAC IAC -> one IAC */
240 G.telstate = TS_COPY;
246 G.telstate = TS_SUB1;
255 /* DATA MARK must be added later */
257 G.telstate = TS_COPY;
261 case TS_OPT: /* Prev chars were IAC WILL/WONT/DO/DONT */
263 G.telstate = TS_COPY;
266 case TS_SUB1: /* Subnegotiation */
267 case TS_SUB2: /* Subnegotiation */
268 subneg(c); /* can change G.telstate */
273 if (G.telstate != TS_NORMAL) {
274 /* We had some IACs, or CR */
277 if (G.telstate == TS_COPY) /* we aren't in the middle of IAC */
278 G.telstate = TS_NORMAL;
283 full_write(STDOUT_FILENO, G.buf, len);
286 static void put_iac(int c)
288 G.iacbuf[G.iaclen++] = c;
291 static void put_iac2(byte wwdd, byte c)
293 if (G.iaclen + 3 > IACBUFSIZE)
301 #if ENABLE_FEATURE_TELNET_TTYPE
302 static void put_iac_subopt(byte c, char *str)
304 int len = strlen(str) + 6; // ( 2 + 1 + 1 + strlen + 2 )
306 if (G.iaclen + len > IACBUFSIZE)
322 #if ENABLE_FEATURE_TELNET_AUTOLOGIN
323 static void put_iac_subopt_autologin(void)
325 int len = strlen(G.autologin) + 6; // (2 + 1 + 1 + strlen + 2)
326 const char *p = "USER";
328 if (G.iaclen + len > IACBUFSIZE)
333 put_iac(TELOPT_NEW_ENVIRON);
335 put_iac(NEW_ENV_VAR);
340 put_iac(NEW_ENV_VALUE);
351 #if ENABLE_FEATURE_AUTOWIDTH
352 static void put_iac_naws(byte c, int x, int y)
354 if (G.iaclen + 9 > IACBUFSIZE)
361 put_iac((x >> 8) & 0xff);
363 put_iac((y >> 8) & 0xff);
371 static char const escapecharis[] ALIGN1 = "\r\nEscape character is ";
373 static void setConMode(void)
375 if (G.telflags & UF_ECHO) {
376 if (G.charmode == CHM_TRY) {
378 printf("\r\nEntering character mode%s'^]'.\r\n", escapecharis);
382 if (G.charmode != CHM_OFF) {
383 G.charmode = CHM_OFF;
384 printf("\r\nEntering line mode%s'^C'.\r\n", escapecharis);
390 static void will_charmode(void)
392 G.charmode = CHM_TRY;
393 G.telflags |= (UF_ECHO | UF_SGA);
396 put_iac2(DO, TELOPT_ECHO);
397 put_iac2(DO, TELOPT_SGA);
401 static void do_linemode(void)
403 G.charmode = CHM_TRY;
404 G.telflags &= ~(UF_ECHO | UF_SGA);
407 put_iac2(DONT, TELOPT_ECHO);
408 put_iac2(DONT, TELOPT_SGA);
412 static void to_notsup(char c)
414 if (G.telwish == WILL)
416 else if (G.telwish == DO)
420 static void to_echo(void)
422 /* if server requests ECHO, don't agree */
423 if (G.telwish == DO) {
424 put_iac2(WONT, TELOPT_ECHO);
427 if (G.telwish == DONT)
430 if (G.telflags & UF_ECHO) {
431 if (G.telwish == WILL)
433 } else if (G.telwish == WONT)
436 if (G.charmode != CHM_OFF)
437 G.telflags ^= UF_ECHO;
439 if (G.telflags & UF_ECHO)
440 put_iac2(DO, TELOPT_ECHO);
442 put_iac2(DONT, TELOPT_ECHO);
445 full_write1_str("\r\n"); /* sudden modec */
448 static void to_sga(void)
450 /* daemon always sends will/wont, client do/dont */
452 if (G.telflags & UF_SGA) {
453 if (G.telwish == WILL)
455 } else if (G.telwish == WONT)
458 G.telflags ^= UF_SGA; /* toggle */
459 if (G.telflags & UF_SGA)
460 put_iac2(DO, TELOPT_SGA);
462 put_iac2(DONT, TELOPT_SGA);
465 #if ENABLE_FEATURE_TELNET_TTYPE
466 static void to_ttype(void)
468 /* Tell server we will (or won't) do TTYPE */
470 put_iac2(WILL, TELOPT_TTYPE);
472 put_iac2(WONT, TELOPT_TTYPE);
476 #if ENABLE_FEATURE_TELNET_AUTOLOGIN
477 static void to_new_environ(void)
479 /* Tell server we will (or will not) do AUTOLOGIN */
481 put_iac2(WILL, TELOPT_NEW_ENVIRON);
483 put_iac2(WONT, TELOPT_NEW_ENVIRON);
487 #if ENABLE_FEATURE_AUTOWIDTH
488 static void to_naws(void)
490 /* Tell server we will do NAWS */
491 put_iac2(WILL, TELOPT_NAWS);
495 static void telopt(byte c)
502 #if ENABLE_FEATURE_TELNET_TTYPE
506 #if ENABLE_FEATURE_TELNET_AUTOLOGIN
507 case TELOPT_NEW_ENVIRON:
508 to_new_environ(); break;
510 #if ENABLE_FEATURE_AUTOWIDTH
513 put_iac_naws(c, G.win_width, G.win_height);
522 /* subnegotiation -- ignore all (except TTYPE,NAWS) */
523 static void subneg(byte c)
525 switch (G.telstate) {
528 G.telstate = TS_SUB2;
529 #if ENABLE_FEATURE_TELNET_TTYPE
531 if (c == TELOPT_TTYPE && G.ttype)
532 put_iac_subopt(TELOPT_TTYPE, G.ttype);
534 #if ENABLE_FEATURE_TELNET_AUTOLOGIN
536 if (c == TELOPT_NEW_ENVIRON && G.autologin)
537 put_iac_subopt_autologin();
542 G.telstate = TS_COPY;
545 G.telstate = TS_SUB1;
550 static void rawmode(void)
553 tcsetattr(0, TCSADRAIN, &G.termios_raw);
556 static void cookmode(void)
559 tcsetattr(0, TCSADRAIN, &G.termios_def);
562 int telnet_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
563 int telnet_main(int argc UNUSED_PARAM, char **argv)
568 struct pollfd ufds[2];
572 #if ENABLE_FEATURE_AUTOWIDTH
573 get_terminal_width_height(0, &G.win_width, &G.win_height);
576 #if ENABLE_FEATURE_TELNET_TTYPE
577 G.ttype = getenv("TERM");
580 if (tcgetattr(0, &G.termios_def) >= 0) {
582 G.termios_raw = G.termios_def;
583 cfmakeraw(&G.termios_raw);
586 #if ENABLE_FEATURE_TELNET_AUTOLOGIN
587 if (1 & getopt32(argv, "al:", &G.autologin))
588 G.autologin = getenv("USER");
596 port = bb_lookup_port(*argv ? *argv++ : "telnet", "tcp", 23);
597 if (*argv) /* extra params?? */
600 xmove_fd(create_and_connect_stream_or_die(host, port), netfd);
602 setsockopt(netfd, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1));
604 signal(SIGINT, record_signo);
606 ufds[0].fd = 0; ufds[1].fd = netfd;
607 ufds[0].events = ufds[1].events = POLLIN;
610 switch (poll(ufds, 2, -1)) {
614 /* error, ignore and/or log something, bay go to loop */
622 if (ufds[0].revents) {
623 len = safe_read(STDIN_FILENO, G.buf, DATABUFSIZE);
625 doexit(EXIT_SUCCESS);
626 TRACE(0, ("Read con: %d\n", len));
627 handle_net_output(len);
630 if (ufds[1].revents) {
631 len = safe_read(netfd, G.buf, DATABUFSIZE);
633 full_write1_str("Connection closed by foreign host\r\n");
634 doexit(EXIT_FAILURE);
636 TRACE(0, ("Read netfd (%d): %d\n", netfd, len));
637 handle_net_input(len);