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 the GPL v2 or later, see the file LICENSE in this tarball.
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>
25 #include <arpa/telnet.h>
26 #include <netinet/in.h>
30 #define TRACE(x, y) do { if (x) printf y; } while (0)
53 typedef unsigned char byte;
56 int netfd; /* console fd:s are 0 and 1 (and 2) */
57 short iaclen; /* could even use byte */
58 byte telstate; /* telnet negotiation state from network input */
59 byte telwish; /* DO, DONT, WILL, WONT */
64 #if ENABLE_FEATURE_TELNET_TTYPE
67 #if ENABLE_FEATURE_TELNET_AUTOLOGIN
68 const char *autologin;
70 #if ENABLE_FEATURE_AUTOWIDTH
71 int win_width, win_height;
73 /* same buffer used both for network and console read/write */
74 char buf[DATABUFSIZE];
75 /* buffer to handle telnet negotiations */
76 char iacbuf[IACBUFSIZE];
77 struct termios termios_def;
78 struct termios termios_raw;
80 #define G (*(struct globals*)&bb_common_bufsiz1)
81 void BUG_telnet_globals_too_big(void);
82 #define INIT_G() do { \
83 if (sizeof(G) > COMMON_BUFSIZE) \
84 BUG_telnet_globals_too_big(); \
85 /* memset(&G, 0, sizeof G); - already is */ \
88 /* Function prototypes */
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 int subneg(byte c);
96 static void iacflush(void)
98 write(G.netfd, G.iacbuf, G.iaclen);
102 #define write_str(fd, str) write(fd, str, sizeof(str) - 1)
104 static void doexit(int ev)
110 static void conescape(void)
114 if (G.gotsig) /* came from line mode... go raw */
117 write_str(1, "\r\nConsole escape. Commands are:\r\n\n"
118 " l go to line mode\r\n"
119 " c go to character mode\r\n"
120 " z suspend telnet\r\n"
121 " e exit telnet\r\n");
123 if (read(0, &b, 1) <= 0)
148 write_str(1, "continuing...\r\n");
158 static void handlenetoutput(int len)
160 /* here we could do smart tricks how to handle 0xFF:s in output
161 * stream like writing twice every sequence of FF:s (thus doing
162 * many write()s. But I think interactive telnet application does
163 * not need to be 100% 8-bit clean, so changing every 0xff:s to
166 * 2002-mar-21, Przemyslaw Czerpak (druzus@polbox.com)
168 * first - I cannot use programs like sz/rz
169 * second - the 0x0D is sent as one character and if the next
170 * char is 0x0A then it's eaten by a server side.
171 * third - whay doy you have to make 'many write()s'?
172 * I don't understand.
173 * So I implemented it. It's realy useful for me. I hope that
174 * others people will find it interesting to.
178 byte * p = (byte*)G.buf;
179 byte outbuf[4*DATABUFSIZE];
181 for (i = len, j = 0; i > 0; i--, p++)
195 write(G.netfd, outbuf, j);
198 static void handlenetinput(int len)
203 for (i = 0; i < len; i++)
207 if (G.telstate == 0) /* most of the time state == 0 */
226 if (c == IAC) /* IAC IAC -> 0xFF */
236 G.telstate = TS_SUB1;
246 G.telstate = TS_0; /* DATA MARK must be added later */
249 case TS_OPT: /* WILL, WONT, DO, DONT */
253 case TS_SUB1: /* Subnegotiation */
254 case TS_SUB2: /* Subnegotiation */
262 if (G.iaclen) iacflush();
263 if (G.telstate == TS_0) G.telstate = 0;
269 write(1, G.buf, len);
272 static void putiac(int c)
274 G.iacbuf[G.iaclen++] = c;
277 static void putiac2(byte wwdd, byte c)
279 if (G.iaclen + 3 > IACBUFSIZE)
287 #if ENABLE_FEATURE_TELNET_TTYPE
288 static void putiac_subopt(byte c, char *str)
290 int len = strlen(str) + 6; // ( 2 + 1 + 1 + strlen + 2 )
292 if (G.iaclen + len > IACBUFSIZE)
308 #if ENABLE_FEATURE_TELNET_AUTOLOGIN
309 static void putiac_subopt_autologin(void)
311 int len = strlen(G.autologin) + 6; // (2 + 1 + 1 + strlen + 2)
312 const char *user = "USER";
314 if (G.iaclen + len > IACBUFSIZE)
319 putiac(TELOPT_NEW_ENVIRON);
326 putiac(NEW_ENV_VALUE);
329 putiac(*G.autologin++);
336 #if ENABLE_FEATURE_AUTOWIDTH
337 static void putiac_naws(byte c, int x, int y)
339 if (G.iaclen + 9 > IACBUFSIZE)
346 putiac((x >> 8) & 0xff);
348 putiac((y >> 8) & 0xff);
356 static char const escapecharis[] = "\r\nEscape character is ";
358 static void setConMode(void)
360 if (G.telflags & UF_ECHO) {
361 if (G.charmode == CHM_TRY) {
363 printf("\r\nEntering character mode%s'^]'.\r\n", escapecharis);
367 if (G.charmode != CHM_OFF) {
368 G.charmode = CHM_OFF;
369 printf("\r\nEntering line mode%s'^C'.\r\n", escapecharis);
375 static void will_charmode(void)
377 G.charmode = CHM_TRY;
378 G.telflags |= (UF_ECHO | UF_SGA);
381 putiac2(DO, TELOPT_ECHO);
382 putiac2(DO, TELOPT_SGA);
386 static void do_linemode(void)
388 G.charmode = CHM_TRY;
389 G.telflags &= ~(UF_ECHO | UF_SGA);
392 putiac2(DONT, TELOPT_ECHO);
393 putiac2(DONT, TELOPT_SGA);
397 static void to_notsup(char c)
399 if (G.telwish == WILL)
401 else if (G.telwish == DO)
405 static void to_echo(void)
407 /* if server requests ECHO, don't agree */
408 if (G.telwish == DO) {
409 putiac2(WONT, TELOPT_ECHO);
412 if (G.telwish == DONT)
415 if (G.telflags & UF_ECHO) {
416 if (G.telwish == WILL)
418 } else if (G.telwish == WONT)
421 if (G.charmode != CHM_OFF)
422 G.telflags ^= UF_ECHO;
424 if (G.telflags & UF_ECHO)
425 putiac2(DO, TELOPT_ECHO);
427 putiac2(DONT, TELOPT_ECHO);
430 write_str(1, "\r\n"); /* sudden modec */
433 static void to_sga(void)
435 /* daemon always sends will/wont, client do/dont */
437 if (G.telflags & UF_SGA) {
438 if (G.telwish == WILL)
440 } else if (G.telwish == WONT)
443 if ((G.telflags ^= UF_SGA) & UF_SGA) /* toggle */
444 putiac2(DO, TELOPT_SGA);
446 putiac2(DONT, TELOPT_SGA);
449 #if ENABLE_FEATURE_TELNET_TTYPE
450 static void to_ttype(void)
452 /* Tell server we will (or won't) do TTYPE */
455 putiac2(WILL, TELOPT_TTYPE);
457 putiac2(WONT, TELOPT_TTYPE);
461 #if ENABLE_FEATURE_TELNET_AUTOLOGIN
462 static void to_new_environ(void)
464 /* Tell server we will (or will not) do AUTOLOGIN */
467 putiac2(WILL, TELOPT_NEW_ENVIRON);
469 putiac2(WONT, TELOPT_NEW_ENVIRON);
473 #if ENABLE_FEATURE_AUTOWIDTH
474 static void to_naws(void)
476 /* Tell server we will do NAWS */
477 putiac2(WILL, TELOPT_NAWS);
481 static void telopt(byte c)
488 #if ENABLE_FEATURE_TELNET_TTYPE
492 #if ENABLE_FEATURE_TELNET_AUTOLOGIN
493 case TELOPT_NEW_ENVIRON:
494 to_new_environ(); break;
496 #if ENABLE_FEATURE_AUTOWIDTH
499 putiac_naws(c, G.win_width, G.win_height);
508 /* subnegotiation -- ignore all (except TTYPE,NAWS) */
509 static int subneg(byte c)
511 switch (G.telstate) {
514 G.telstate = TS_SUB2;
515 #if ENABLE_FEATURE_TELNET_TTYPE
517 if (c == TELOPT_TTYPE)
518 putiac_subopt(TELOPT_TTYPE, G.ttype);
520 #if ENABLE_FEATURE_TELNET_AUTOLOGIN
522 if (c == TELOPT_NEW_ENVIRON)
523 putiac_subopt_autologin();
529 G.telstate = TS_SUB1;
535 static void fgotsig(int sig)
541 static void rawmode(void)
544 tcsetattr(0, TCSADRAIN, &G.termios_raw);
547 static void cookmode(void)
550 tcsetattr(0, TCSADRAIN, &G.termios_def);
553 int telnet_main(int argc, char** argv);
554 int telnet_main(int argc, char** argv)
560 struct pollfd ufds[2];
568 #if ENABLE_FEATURE_AUTOWIDTH
569 get_terminal_width_height(0, &G.win_width, &G.win_height);
572 #if ENABLE_FEATURE_TELNET_TTYPE
573 G.ttype = getenv("TERM");
576 if (tcgetattr(0, &G.termios_def) >= 0) {
578 G.termios_raw = G.termios_def;
579 cfmakeraw(&G.termios_raw);
585 #if ENABLE_FEATURE_TELNET_AUTOLOGIN
586 if (1 & getopt32(argc, argv, "al:", &G.autologin))
587 G.autologin = getenv("USER");
595 port = bb_lookup_port(*argv ? *argv++ : "telnet", "tcp", 23);
596 if (*argv) /* extra params?? */
599 G.netfd = create_and_connect_stream_or_die(host, port);
601 setsockopt(G.netfd, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1));
603 signal(SIGINT, fgotsig);
606 ufds[0].fd = 0; ufds[1].fd = G.netfd;
607 ufds[0].events = ufds[1].events = POLLIN;
611 FD_SET(G.netfd, &readfds);
617 fd_set rfds = readfds;
619 switch (select(maxfd, &rfds, NULL, NULL, NULL))
621 switch (poll(ufds, 2, -1))
627 /* error, ignore and/or log something, bay go to loop */
636 if (ufds[0].revents) /* well, should check POLLIN, but ... */
638 if (FD_ISSET(0, &rfds))
641 len = read(0, G.buf, DATABUFSIZE);
644 TRACE(0, ("Read con: %d\n", len));
645 handlenetoutput(len);
649 if (ufds[1].revents) /* well, should check POLLIN, but ... */
651 if (FD_ISSET(G.netfd, &rfds))
654 len = read(G.netfd, G.buf, DATABUFSIZE);
656 write_str(1, "Connection closed by foreign host\r\n");
659 TRACE(0, ("Read netfd (%d): %d\n", G.netfd, len));