source: MondoRescue/branches/3.3/mindi-busybox/networking/telnet.c@ 3621

Last change on this file since 3621 was 3621, checked in by Bruno Cornec, 7 years ago

New 3?3 banch for incorporation of latest busybox 1.25. Changing minor version to handle potential incompatibilities.
File size: 13.0 KB
Line 
1/* vi: set sw=4 ts=4: */
2/*
3 * telnet implementation for busybox
4 *
5 * Author: Tomi Ollila <too@iki.fi>
6 * Copyright (C) 1994-2000 by Tomi Ollila
7 *
8 * Created: Thu Apr 7 13:29:41 1994 too
9 * Last modified: Fri Jun 9 14:34:24 2000 too
10 *
11 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
12 *
13 * HISTORY
14 * Revision 3.1 1994/04/17 11:31:54 too
15 * initial revision
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
18 * <jam@ltsp.org>
19 * Modified 2004/02/11 to add ability to pass the USER variable to remote host
20 * by Fernando Silveira <swrh@gmx.net>
21 *
22 */
23
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"
31//usage:
32//usage:#else
33//usage:#define telnet_trivial_usage
34//usage: "HOST [PORT]"
35//usage:#define telnet_full_usage "\n\n"
36//usage: "Connect to telnet server"
37//usage:#endif
38
39#include <arpa/telnet.h>
40#include <netinet/in.h>
41#include "libbb.h"
42#include "common_bufsiz.h"
43
44#ifdef __BIONIC__
45/* should be in arpa/telnet.h */
46# define IAC 255 /* interpret as command: */
47# define DONT 254 /* you are not to use option */
48# define DO 253 /* please, you use option */
49# define WONT 252 /* I won't use option */
50# define WILL 251 /* I will use option */
51# define SB 250 /* interpret as subnegotiation */
52# define SE 240 /* end sub negotiation */
53# define TELOPT_ECHO 1 /* echo */
54# define TELOPT_SGA 3 /* suppress go ahead */
55# define TELOPT_TTYPE 24 /* terminal type */
56# define TELOPT_NAWS 31 /* window size */
57#endif
58
59#ifdef DOTRACE
60# define TRACE(x, y) do { if (x) printf y; } while (0)
61#else
62# define TRACE(x, y)
63#endif
64
65enum {
66 DATABUFSIZE = 128,
67 IACBUFSIZE = 128,
68
69 CHM_TRY = 0,
70 CHM_ON = 1,
71 CHM_OFF = 2,
72
73 UF_ECHO = 0x01,
74 UF_SGA = 0x02,
75
76 TS_NORMAL = 0,
77 TS_COPY = 1,
78 TS_IAC = 2,
79 TS_OPT = 3,
80 TS_SUB1 = 4,
81 TS_SUB2 = 5,
82 TS_CR = 6,
83};
84
85typedef unsigned char byte;
86
87enum { netfd = 3 };
88
89struct globals {
90 int iaclen; /* could even use byte, but it's a loss on x86 */
91 byte telstate; /* telnet negotiation state from network input */
92 byte telwish; /* DO, DONT, WILL, WONT */
93 byte charmode;
94 byte telflags;
95 byte do_termios;
96#if ENABLE_FEATURE_TELNET_TTYPE
97 char *ttype;
98#endif
99#if ENABLE_FEATURE_TELNET_AUTOLOGIN
100 const char *autologin;
101#endif
102#if ENABLE_FEATURE_AUTOWIDTH
103 unsigned win_width, win_height;
104#endif
105 /* same buffer used both for network and console read/write */
106 char buf[DATABUFSIZE];
107 /* buffer to handle telnet negotiations */
108 char iacbuf[IACBUFSIZE];
109 struct termios termios_def;
110 struct termios termios_raw;
111} FIX_ALIASING;
112#define G (*(struct globals*)bb_common_bufsiz1)
113#define INIT_G() do { \
114 setup_common_bufsiz(); \
115 BUILD_BUG_ON(sizeof(G) > COMMON_BUFSIZE); \
116} while (0)
117
118
119static void rawmode(void);
120static void cookmode(void);
121static void do_linemode(void);
122static void will_charmode(void);
123static void telopt(byte c);
124static void subneg(byte c);
125
126static void iac_flush(void)
127{
128 full_write(netfd, G.iacbuf, G.iaclen);
129 G.iaclen = 0;
130}
131
132static void doexit(int ev) NORETURN;
133static void doexit(int ev)
134{
135 cookmode();
136 exit(ev);
137}
138
139static void con_escape(void)
140{
141 char b;
142
143 if (bb_got_signal) /* came from line mode... go raw */
144 rawmode();
145
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");
151
152 if (read(STDIN_FILENO, &b, 1) <= 0)
153 doexit(EXIT_FAILURE);
154
155 switch (b) {
156 case 'l':
157 if (!bb_got_signal) {
158 do_linemode();
159 goto ret;
160 }
161 break;
162 case 'c':
163 if (bb_got_signal) {
164 will_charmode();
165 goto ret;
166 }
167 break;
168 case 'z':
169 cookmode();
170 kill(0, SIGTSTP);
171 rawmode();
172 break;
173 case 'e':
174 doexit(EXIT_SUCCESS);
175 }
176
177 full_write1_str("continuing...\r\n");
178
179 if (bb_got_signal)
180 cookmode();
181 ret:
182 bb_got_signal = 0;
183}
184
185static void handle_net_output(int len)
186{
187 byte outbuf[2 * DATABUFSIZE];
188 byte *dst = outbuf;
189 byte *src = (byte*)G.buf;
190 byte *end = src + len;
191
192 while (src < end) {
193 byte c = *src++;
194 if (c == 0x1d) {
195 con_escape();
196 return;
197 }
198 *dst = c;
199 if (c == IAC)
200 *++dst = c; /* IAC -> IAC IAC */
201 else
202 if (c == '\r' || c == '\n') {
203 /* Enter key sends '\r' in raw mode and '\n' in cooked one.
204 *
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.
208 */
209 *dst = '\r'; /* Enter -> CR LF */
210 *++dst = '\n';
211 }
212 dst++;
213 }
214 if (dst - outbuf != 0)
215 full_write(netfd, outbuf, dst - outbuf);
216}
217
218static void handle_net_input(int len)
219{
220 int i;
221 int cstart = 0;
222
223 for (i = 0; i < len; i++) {
224 byte c = G.buf[i];
225
226 if (G.telstate == TS_NORMAL) { /* most typical state */
227 if (c == IAC) {
228 cstart = i;
229 G.telstate = TS_IAC;
230 }
231 else if (c == '\r') {
232 cstart = i + 1;
233 G.telstate = TS_CR;
234 }
235 /* No IACs were seen so far, no need to copy
236 * bytes within G.buf: */
237 continue;
238 }
239
240 switch (G.telstate) {
241 case TS_CR:
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.
244 */
245 G.telstate = TS_COPY;
246 if (c == '\0')
247 break;
248 /* else: fall through - need to handle CR IAC ... properly */
249
250 case TS_COPY: /* Prev char was ordinary */
251 /* Similar to NORMAL, but in TS_COPY we need to copy bytes */
252 if (c == IAC)
253 G.telstate = TS_IAC;
254 else
255 G.buf[cstart++] = c;
256 if (c == '\r')
257 G.telstate = TS_CR;
258 break;
259
260 case TS_IAC: /* Prev char was IAC */
261 if (c == IAC) { /* IAC IAC -> one IAC */
262 G.buf[cstart++] = c;
263 G.telstate = TS_COPY;
264 break;
265 }
266 /* else */
267 switch (c) {
268 case SB:
269 G.telstate = TS_SUB1;
270 break;
271 case DO:
272 case DONT:
273 case WILL:
274 case WONT:
275 G.telwish = c;
276 G.telstate = TS_OPT;
277 break;
278 /* DATA MARK must be added later */
279 default:
280 G.telstate = TS_COPY;
281 }
282 break;
283
284 case TS_OPT: /* Prev chars were IAC WILL/WONT/DO/DONT */
285 telopt(c);
286 G.telstate = TS_COPY;
287 break;
288
289 case TS_SUB1: /* Subnegotiation */
290 case TS_SUB2: /* Subnegotiation */
291 subneg(c); /* can change G.telstate */
292 break;
293 }
294 }
295
296 if (G.telstate != TS_NORMAL) {
297 /* We had some IACs, or CR */
298 if (G.iaclen)
299 iac_flush();
300 if (G.telstate == TS_COPY) /* we aren't in the middle of IAC */
301 G.telstate = TS_NORMAL;
302 len = cstart;
303 }
304
305 if (len)
306 full_write(STDOUT_FILENO, G.buf, len);
307}
308
309static void put_iac(int c)
310{
311 G.iacbuf[G.iaclen++] = c;
312}
313
314static void put_iac2(byte wwdd, byte c)
315{
316 if (G.iaclen + 3 > IACBUFSIZE)
317 iac_flush();
318
319 put_iac(IAC);
320 put_iac(wwdd);
321 put_iac(c);
322}
323
324#if ENABLE_FEATURE_TELNET_TTYPE
325static void put_iac_subopt(byte c, char *str)
326{
327 int len = strlen(str) + 6; // ( 2 + 1 + 1 + strlen + 2 )
328
329 if (G.iaclen + len > IACBUFSIZE)
330 iac_flush();
331
332 put_iac(IAC);
333 put_iac(SB);
334 put_iac(c);
335 put_iac(0);
336
337 while (*str)
338 put_iac(*str++);
339
340 put_iac(IAC);
341 put_iac(SE);
342}
343#endif
344
345#if ENABLE_FEATURE_TELNET_AUTOLOGIN
346static void put_iac_subopt_autologin(void)
347{
348 int len = strlen(G.autologin) + 6; // (2 + 1 + 1 + strlen + 2)
349 const char *p = "USER";
350
351 if (G.iaclen + len > IACBUFSIZE)
352 iac_flush();
353
354 put_iac(IAC);
355 put_iac(SB);
356 put_iac(TELOPT_NEW_ENVIRON);
357 put_iac(TELQUAL_IS);
358 put_iac(NEW_ENV_VAR);
359
360 while (*p)
361 put_iac(*p++);
362
363 put_iac(NEW_ENV_VALUE);
364
365 p = G.autologin;
366 while (*p)
367 put_iac(*p++);
368
369 put_iac(IAC);
370 put_iac(SE);
371}
372#endif
373
374#if ENABLE_FEATURE_AUTOWIDTH
375static void put_iac_naws(byte c, int x, int y)
376{
377 if (G.iaclen + 9 > IACBUFSIZE)
378 iac_flush();
379
380 put_iac(IAC);
381 put_iac(SB);
382 put_iac(c);
383
384 /* "... & 0xff" implicitly done below */
385 put_iac(x >> 8);
386 put_iac(x);
387 put_iac(y >> 8);
388 put_iac(y);
389
390 put_iac(IAC);
391 put_iac(SE);
392}
393#endif
394
395static void setConMode(void)
396{
397 if (G.telflags & UF_ECHO) {
398 if (G.charmode == CHM_TRY) {
399 G.charmode = CHM_ON;
400 printf("\r\nEntering %s mode"
401 "\r\nEscape character is '^%c'.\r\n", "character", ']');
402 rawmode();
403 }
404 } else {
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');
409 cookmode();
410 }
411 }
412}
413
414static void will_charmode(void)
415{
416 G.charmode = CHM_TRY;
417 G.telflags |= (UF_ECHO | UF_SGA);
418 setConMode();
419
420 put_iac2(DO, TELOPT_ECHO);
421 put_iac2(DO, TELOPT_SGA);
422 iac_flush();
423}
424
425static void do_linemode(void)
426{
427 G.charmode = CHM_TRY;
428 G.telflags &= ~(UF_ECHO | UF_SGA);
429 setConMode();
430
431 put_iac2(DONT, TELOPT_ECHO);
432 put_iac2(DONT, TELOPT_SGA);
433 iac_flush();
434}
435
436static void to_notsup(char c)
437{
438 if (G.telwish == WILL)
439 put_iac2(DONT, c);
440 else if (G.telwish == DO)
441 put_iac2(WONT, c);
442}
443
444static void to_echo(void)
445{
446 /* if server requests ECHO, don't agree */
447 if (G.telwish == DO) {
448 put_iac2(WONT, TELOPT_ECHO);
449 return;
450 }
451 if (G.telwish == DONT)
452 return;
453
454 if (G.telflags & UF_ECHO) {
455 if (G.telwish == WILL)
456 return;
457 } else if (G.telwish == WONT)
458 return;
459
460 if (G.charmode != CHM_OFF)
461 G.telflags ^= UF_ECHO;
462
463 if (G.telflags & UF_ECHO)
464 put_iac2(DO, TELOPT_ECHO);
465 else
466 put_iac2(DONT, TELOPT_ECHO);
467
468 setConMode();
469 full_write1_str("\r\n"); /* sudden modec */
470}
471
472static void to_sga(void)
473{
474 /* daemon always sends will/wont, client do/dont */
475
476 if (G.telflags & UF_SGA) {
477 if (G.telwish == WILL)
478 return;
479 } else if (G.telwish == WONT)
480 return;
481
482 G.telflags ^= UF_SGA; /* toggle */
483 if (G.telflags & UF_SGA)
484 put_iac2(DO, TELOPT_SGA);
485 else
486 put_iac2(DONT, TELOPT_SGA);
487}
488
489#if ENABLE_FEATURE_TELNET_TTYPE
490static void to_ttype(void)
491{
492 /* Tell server we will (or won't) do TTYPE */
493 if (G.ttype)
494 put_iac2(WILL, TELOPT_TTYPE);
495 else
496 put_iac2(WONT, TELOPT_TTYPE);
497}
498#endif
499
500#if ENABLE_FEATURE_TELNET_AUTOLOGIN
501static void to_new_environ(void)
502{
503 /* Tell server we will (or will not) do AUTOLOGIN */
504 if (G.autologin)
505 put_iac2(WILL, TELOPT_NEW_ENVIRON);
506 else
507 put_iac2(WONT, TELOPT_NEW_ENVIRON);
508}
509#endif
510
511#if ENABLE_FEATURE_AUTOWIDTH
512static void to_naws(void)
513{
514 /* Tell server we will do NAWS */
515 put_iac2(WILL, TELOPT_NAWS);
516}
517#endif
518
519static void telopt(byte c)
520{
521 switch (c) {
522 case TELOPT_ECHO:
523 to_echo(); break;
524 case TELOPT_SGA:
525 to_sga(); break;
526#if ENABLE_FEATURE_TELNET_TTYPE
527 case TELOPT_TTYPE:
528 to_ttype(); break;
529#endif
530#if ENABLE_FEATURE_TELNET_AUTOLOGIN
531 case TELOPT_NEW_ENVIRON:
532 to_new_environ(); break;
533#endif
534#if ENABLE_FEATURE_AUTOWIDTH
535 case TELOPT_NAWS:
536 to_naws();
537 put_iac_naws(c, G.win_width, G.win_height);
538 break;
539#endif
540 default:
541 to_notsup(c);
542 break;
543 }
544}
545
546/* subnegotiation -- ignore all (except TTYPE,NAWS) */
547static void subneg(byte c)
548{
549 switch (G.telstate) {
550 case TS_SUB1:
551 if (c == IAC)
552 G.telstate = TS_SUB2;
553#if ENABLE_FEATURE_TELNET_TTYPE
554 else
555 if (c == TELOPT_TTYPE && G.ttype)
556 put_iac_subopt(TELOPT_TTYPE, G.ttype);
557#endif
558#if ENABLE_FEATURE_TELNET_AUTOLOGIN
559 else
560 if (c == TELOPT_NEW_ENVIRON && G.autologin)
561 put_iac_subopt_autologin();
562#endif
563 break;
564 case TS_SUB2:
565 if (c == SE) {
566 G.telstate = TS_COPY;
567 return;
568 }
569 G.telstate = TS_SUB1;
570 break;
571 }
572}
573
574static void rawmode(void)
575{
576 if (G.do_termios)
577 tcsetattr(0, TCSADRAIN, &G.termios_raw);
578}
579
580static void cookmode(void)
581{
582 if (G.do_termios)
583 tcsetattr(0, TCSADRAIN, &G.termios_def);
584}
585
586int telnet_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
587int telnet_main(int argc UNUSED_PARAM, char **argv)
588{
589 char *host;
590 int port;
591 int len;
592 struct pollfd ufds[2];
593
594 INIT_G();
595
596#if ENABLE_FEATURE_AUTOWIDTH
597 get_terminal_width_height(0, &G.win_width, &G.win_height);
598#endif
599
600#if ENABLE_FEATURE_TELNET_TTYPE
601 G.ttype = getenv("TERM");
602#endif
603
604 if (tcgetattr(0, &G.termios_def) >= 0) {
605 G.do_termios = 1;
606 G.termios_raw = G.termios_def;
607 cfmakeraw(&G.termios_raw);
608 }
609
610#if ENABLE_FEATURE_TELNET_AUTOLOGIN
611 if (1 & getopt32(argv, "al:", &G.autologin))
612 G.autologin = getenv("USER");
613 argv += optind;
614#else
615 argv++;
616#endif
617 if (!*argv)
618 bb_show_usage();
619 host = *argv++;
620 port = bb_lookup_port(*argv ? *argv++ : "telnet", "tcp", 23);
621 if (*argv) /* extra params?? */
622 bb_show_usage();
623
624 xmove_fd(create_and_connect_stream_or_die(host, port), netfd);
625
626 setsockopt_keepalive(netfd);
627
628 signal(SIGINT, record_signo);
629
630 ufds[0].fd = STDIN_FILENO;
631 ufds[0].events = POLLIN;
632 ufds[1].fd = netfd;
633 ufds[1].events = POLLIN;
634
635 while (1) {
636 if (poll(ufds, 2, -1) < 0) {
637 /* error, ignore and/or log something, bay go to loop */
638 if (bb_got_signal)
639 con_escape();
640 else
641 sleep(1);
642 continue;
643 }
644
645// FIXME: reads can block. Need full bidirectional buffering.
646
647 if (ufds[0].revents) {
648 len = safe_read(STDIN_FILENO, G.buf, DATABUFSIZE);
649 if (len <= 0)
650 doexit(EXIT_SUCCESS);
651 TRACE(0, ("Read con: %d\n", len));
652 handle_net_output(len);
653 }
654
655 if (ufds[1].revents) {
656 len = safe_read(netfd, G.buf, DATABUFSIZE);
657 if (len <= 0) {
658 full_write1_str("Connection closed by foreign host\r\n");
659 doexit(EXIT_FAILURE);
660 }
661 TRACE(0, ("Read netfd (%d): %d\n", netfd, len));
662 handle_net_input(len);
663 }
664 } /* while (1) */
665}
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