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) ATTRIBUTE_NORETURN;
105 static void doexit(int ev)
111 static void conescape(void)
115 if (G.gotsig) /* 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(0, &b, 1) <= 0)
149 write_str(1, "continuing...\r\n");
159 static void handlenetoutput(int len)
161 /* here we could do smart tricks how to handle 0xFF:s in output
162 * stream like writing twice every sequence of FF:s (thus doing
163 * many write()s. But I think interactive telnet application does
164 * not need to be 100% 8-bit clean, so changing every 0xff:s to
167 * 2002-mar-21, Przemyslaw Czerpak (druzus@polbox.com)
169 * first - I cannot use programs like sz/rz
170 * second - the 0x0D is sent as one character and if the next
171 * char is 0x0A then it's eaten by a server side.
172 * third - whay doy you have to make 'many write()s'?
173 * I don't understand.
174 * So I implemented it. It's realy useful for me. I hope that
175 * others people will find it interesting too.
179 byte * p = (byte*)G.buf;
180 byte outbuf[4*DATABUFSIZE];
182 for (i = len, j = 0; i > 0; i--, p++) {
194 write(G.netfd, outbuf, j);
197 static void handlenetinput(int len)
202 for (i = 0; i < len; i++) {
205 if (G.telstate == 0) { /* most of the time state == 0 */
211 switch (G.telstate) {
220 if (c == IAC) { /* IAC IAC -> 0xFF */
228 G.telstate = TS_SUB1;
238 G.telstate = TS_0; /* DATA MARK must be added later */
241 case TS_OPT: /* WILL, WONT, DO, DONT */
245 case TS_SUB1: /* Subnegotiation */
246 case TS_SUB2: /* Subnegotiation */
253 if (G.iaclen) iacflush();
254 if (G.telstate == TS_0) G.telstate = 0;
259 write(1, G.buf, len);
262 static void putiac(int c)
264 G.iacbuf[G.iaclen++] = c;
267 static void putiac2(byte wwdd, byte c)
269 if (G.iaclen + 3 > IACBUFSIZE)
277 #if ENABLE_FEATURE_TELNET_TTYPE
278 static void putiac_subopt(byte c, char *str)
280 int len = strlen(str) + 6; // ( 2 + 1 + 1 + strlen + 2 )
282 if (G.iaclen + len > IACBUFSIZE)
298 #if ENABLE_FEATURE_TELNET_AUTOLOGIN
299 static void putiac_subopt_autologin(void)
301 int len = strlen(G.autologin) + 6; // (2 + 1 + 1 + strlen + 2)
302 const char *user = "USER";
304 if (G.iaclen + len > IACBUFSIZE)
309 putiac(TELOPT_NEW_ENVIRON);
316 putiac(NEW_ENV_VALUE);
319 putiac(*G.autologin++);
326 #if ENABLE_FEATURE_AUTOWIDTH
327 static void putiac_naws(byte c, int x, int y)
329 if (G.iaclen + 9 > IACBUFSIZE)
336 putiac((x >> 8) & 0xff);
338 putiac((y >> 8) & 0xff);
346 static char const escapecharis[] ALIGN1 = "\r\nEscape character is ";
348 static void setConMode(void)
350 if (G.telflags & UF_ECHO) {
351 if (G.charmode == CHM_TRY) {
353 printf("\r\nEntering character mode%s'^]'.\r\n", escapecharis);
357 if (G.charmode != CHM_OFF) {
358 G.charmode = CHM_OFF;
359 printf("\r\nEntering line mode%s'^C'.\r\n", escapecharis);
365 static void will_charmode(void)
367 G.charmode = CHM_TRY;
368 G.telflags |= (UF_ECHO | UF_SGA);
371 putiac2(DO, TELOPT_ECHO);
372 putiac2(DO, TELOPT_SGA);
376 static void do_linemode(void)
378 G.charmode = CHM_TRY;
379 G.telflags &= ~(UF_ECHO | UF_SGA);
382 putiac2(DONT, TELOPT_ECHO);
383 putiac2(DONT, TELOPT_SGA);
387 static void to_notsup(char c)
389 if (G.telwish == WILL)
391 else if (G.telwish == DO)
395 static void to_echo(void)
397 /* if server requests ECHO, don't agree */
398 if (G.telwish == DO) {
399 putiac2(WONT, TELOPT_ECHO);
402 if (G.telwish == DONT)
405 if (G.telflags & UF_ECHO) {
406 if (G.telwish == WILL)
408 } else if (G.telwish == WONT)
411 if (G.charmode != CHM_OFF)
412 G.telflags ^= UF_ECHO;
414 if (G.telflags & UF_ECHO)
415 putiac2(DO, TELOPT_ECHO);
417 putiac2(DONT, TELOPT_ECHO);
420 write_str(1, "\r\n"); /* sudden modec */
423 static void to_sga(void)
425 /* daemon always sends will/wont, client do/dont */
427 if (G.telflags & UF_SGA) {
428 if (G.telwish == WILL)
430 } else if (G.telwish == WONT)
433 G.telflags ^= UF_SGA; /* toggle */
434 if (G.telflags & UF_SGA)
435 putiac2(DO, TELOPT_SGA);
437 putiac2(DONT, TELOPT_SGA);
440 #if ENABLE_FEATURE_TELNET_TTYPE
441 static void to_ttype(void)
443 /* Tell server we will (or won't) do TTYPE */
446 putiac2(WILL, TELOPT_TTYPE);
448 putiac2(WONT, TELOPT_TTYPE);
452 #if ENABLE_FEATURE_TELNET_AUTOLOGIN
453 static void to_new_environ(void)
455 /* Tell server we will (or will not) do AUTOLOGIN */
458 putiac2(WILL, TELOPT_NEW_ENVIRON);
460 putiac2(WONT, TELOPT_NEW_ENVIRON);
464 #if ENABLE_FEATURE_AUTOWIDTH
465 static void to_naws(void)
467 /* Tell server we will do NAWS */
468 putiac2(WILL, TELOPT_NAWS);
472 static void telopt(byte c)
479 #if ENABLE_FEATURE_TELNET_TTYPE
483 #if ENABLE_FEATURE_TELNET_AUTOLOGIN
484 case TELOPT_NEW_ENVIRON:
485 to_new_environ(); break;
487 #if ENABLE_FEATURE_AUTOWIDTH
490 putiac_naws(c, G.win_width, G.win_height);
499 /* subnegotiation -- ignore all (except TTYPE,NAWS) */
500 static int subneg(byte c)
502 switch (G.telstate) {
505 G.telstate = TS_SUB2;
506 #if ENABLE_FEATURE_TELNET_TTYPE
508 if (c == TELOPT_TTYPE)
509 putiac_subopt(TELOPT_TTYPE, G.ttype);
511 #if ENABLE_FEATURE_TELNET_AUTOLOGIN
513 if (c == TELOPT_NEW_ENVIRON)
514 putiac_subopt_autologin();
520 G.telstate = TS_SUB1;
526 static void fgotsig(int sig)
532 static void rawmode(void)
535 tcsetattr(0, TCSADRAIN, &G.termios_raw);
538 static void cookmode(void)
541 tcsetattr(0, TCSADRAIN, &G.termios_def);
544 /* poll gives smaller (-70 bytes) code */
547 int telnet_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
548 int telnet_main(int argc, char **argv)
554 struct pollfd ufds[2];
562 #if ENABLE_FEATURE_AUTOWIDTH
563 get_terminal_width_height(0, &G.win_width, &G.win_height);
566 #if ENABLE_FEATURE_TELNET_TTYPE
567 G.ttype = getenv("TERM");
570 if (tcgetattr(0, &G.termios_def) >= 0) {
572 G.termios_raw = G.termios_def;
573 cfmakeraw(&G.termios_raw);
579 #if ENABLE_FEATURE_TELNET_AUTOLOGIN
580 if (1 & getopt32(argv, "al:", &G.autologin))
581 G.autologin = getenv("USER");
589 port = bb_lookup_port(*argv ? *argv++ : "telnet", "tcp", 23);
590 if (*argv) /* extra params?? */
593 G.netfd = create_and_connect_stream_or_die(host, port);
595 setsockopt(G.netfd, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1));
597 signal(SIGINT, fgotsig);
600 ufds[0].fd = 0; ufds[1].fd = G.netfd;
601 ufds[0].events = ufds[1].events = POLLIN;
605 FD_SET(G.netfd, &readfds);
611 fd_set rfds = readfds;
613 switch (select(maxfd, &rfds, NULL, NULL, NULL))
615 switch (poll(ufds, 2, -1))
621 /* error, ignore and/or log something, bay go to loop */
630 if (ufds[0].revents) /* well, should check POLLIN, but ... */
632 if (FD_ISSET(0, &rfds))
635 len = read(0, G.buf, DATABUFSIZE);
638 TRACE(0, ("Read con: %d\n", len));
639 handlenetoutput(len);
643 if (ufds[1].revents) /* well, should check POLLIN, but ... */
645 if (FD_ISSET(G.netfd, &rfds))
648 len = read(G.netfd, G.buf, DATABUFSIZE);
650 write_str(1, "Connection closed by foreign host\r\n");
653 TRACE(0, ("Read netfd (%d): %d\n", G.netfd, len));