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)
35 #define DATABUFSIZE 128
36 #define IACBUFSIZE 128
53 #define WriteCS(fd, str) write(fd, str, sizeof str -1)
55 typedef unsigned char byte;
57 /* use globals to reduce size ??? */ /* test this hypothesis later */
58 static struct Globalvars {
59 int netfd; /* console fd:s are 0 and 1 (and 2) */
60 /* same buffer used both for network and console read/write */
61 char buf[DATABUFSIZE]; /* allocating so static size is smaller */
62 byte telstate; /* telnet negotiation state from network input */
63 byte telwish; /* DO, DONT, WILL, WONT */
68 /* buffer to handle telnet negotiations */
69 char iacbuf[IACBUFSIZE];
70 short iaclen; /* could even use byte */
71 struct termios termios_def;
72 struct termios termios_raw;
75 #define xUSE_GLOBALVAR_PTR /* xUSE... -> don't use :D (makes smaller code) */
77 #ifdef USE_GLOBALVAR_PTR
78 struct Globalvars * Gptr;
82 static void iacflush(void)
84 write(G.netfd, G.iacbuf, G.iaclen);
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);
97 #ifdef CONFIG_FEATURE_TELNET_TTYPE
101 #ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
102 static const char *autologin;
105 #ifdef CONFIG_FEATURE_AUTOWIDTH
106 static int win_width, win_height;
109 static void doexit(int ev)
115 static void conescape(void)
119 if (G.gotsig) /* came from line mode... go raw */
122 WriteCS(1, "\r\nConsole escape. Commands are:\r\n\n"
123 " l go to line mode\r\n"
124 " c go to character mode\r\n"
125 " z suspend telnet\r\n"
126 " e exit telnet\r\n");
128 if (read(0, &b, 1) <= 0)
156 WriteCS(1, "continuing...\r\n");
165 static void handlenetoutput(int len)
167 /* here we could do smart tricks how to handle 0xFF:s in output
168 * stream like writing twice every sequence of FF:s (thus doing
169 * many write()s. But I think interactive telnet application does
170 * not need to be 100% 8-bit clean, so changing every 0xff:s to
173 * 2002-mar-21, Przemyslaw Czerpak (druzus@polbox.com)
175 * first - I cannot use programs like sz/rz
176 * second - the 0x0D is sent as one character and if the next
177 * char is 0x0A then it's eaten by a server side.
178 * third - whay doy you have to make 'many write()s'?
179 * I don't understand.
180 * So I implemented it. It's realy useful for me. I hope that
181 * others people will find it interesting to.
185 byte * p = (byte*)G.buf;
186 byte outbuf[4*DATABUFSIZE];
188 for (i = len, j = 0; i > 0; i--, p++)
202 write(G.netfd, outbuf, j);
206 static void handlenetinput(int len)
211 for (i = 0; i < len; i++)
215 if (G.telstate == 0) /* most of the time state == 0 */
234 if (c == IAC) /* IAC IAC -> 0xFF */
244 G.telstate = TS_SUB1;
254 G.telstate = TS_0; /* DATA MARK must be added later */
257 case TS_OPT: /* WILL, WONT, DO, DONT */
261 case TS_SUB1: /* Subnegotiation */
262 case TS_SUB2: /* Subnegotiation */
270 if (G.iaclen) iacflush();
271 if (G.telstate == TS_0) G.telstate = 0;
277 write(1, G.buf, len);
281 /* ******************************* */
283 static void putiac(int c)
285 G.iacbuf[G.iaclen++] = c;
289 static void putiac2(byte wwdd, byte c)
291 if (G.iaclen + 3 > IACBUFSIZE)
299 #ifdef CONFIG_FEATURE_TELNET_TTYPE
300 static void putiac_subopt(byte c, char *str)
302 int len = strlen(str) + 6; // ( 2 + 1 + 1 + strlen + 2 )
304 if (G.iaclen + len > IACBUFSIZE)
320 #ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
321 static void putiac_subopt_autologin(void)
323 int len = strlen(autologin) + 6; // (2 + 1 + 1 + strlen + 2)
324 const char *user = "USER";
326 if (G.iaclen + len > IACBUFSIZE)
331 putiac(TELOPT_NEW_ENVIRON);
338 putiac(NEW_ENV_VALUE);
341 putiac(*autologin++);
348 #ifdef CONFIG_FEATURE_AUTOWIDTH
349 static void putiac_naws(byte c, int x, int y)
351 if (G.iaclen + 9 > IACBUFSIZE)
358 putiac((x >> 8) & 0xff);
360 putiac((y >> 8) & 0xff);
368 /* void putiacstring (subneg strings) */
370 /* ******************************* */
372 static char const escapecharis[] = "\r\nEscape character is ";
374 static void setConMode(void)
376 if (G.telflags & UF_ECHO)
378 if (G.charmode == CHM_TRY) {
380 printf("\r\nEntering character mode%s'^]'.\r\n", escapecharis);
386 if (G.charmode != CHM_OFF) {
387 G.charmode = CHM_OFF;
388 printf("\r\nEntering line mode%s'^C'.\r\n", escapecharis);
394 /* ******************************* */
396 static void will_charmode(void)
398 G.charmode = CHM_TRY;
399 G.telflags |= (UF_ECHO | UF_SGA);
402 putiac2(DO, TELOPT_ECHO);
403 putiac2(DO, TELOPT_SGA);
407 static void do_linemode(void)
409 G.charmode = CHM_TRY;
410 G.telflags &= ~(UF_ECHO | UF_SGA);
413 putiac2(DONT, TELOPT_ECHO);
414 putiac2(DONT, TELOPT_SGA);
418 /* ******************************* */
420 static void to_notsup(char c)
422 if (G.telwish == WILL) putiac2(DONT, c);
423 else if (G.telwish == DO) putiac2(WONT, c);
426 static void to_echo(void)
428 /* if server requests ECHO, don't agree */
429 if (G.telwish == DO) { putiac2(WONT, TELOPT_ECHO); return; }
430 else if (G.telwish == DONT) return;
432 if (G.telflags & UF_ECHO)
434 if (G.telwish == WILL)
438 if (G.telwish == WONT)
441 if (G.charmode != CHM_OFF)
442 G.telflags ^= UF_ECHO;
444 if (G.telflags & UF_ECHO)
445 putiac2(DO, TELOPT_ECHO);
447 putiac2(DONT, TELOPT_ECHO);
450 WriteCS(1, "\r\n"); /* sudden modec */
453 static void to_sga(void)
455 /* daemon always sends will/wont, client do/dont */
457 if (G.telflags & UF_SGA)
459 if (G.telwish == WILL)
463 if (G.telwish == WONT)
466 if ((G.telflags ^= UF_SGA) & UF_SGA) /* toggle */
467 putiac2(DO, TELOPT_SGA);
469 putiac2(DONT, TELOPT_SGA);
474 #ifdef CONFIG_FEATURE_TELNET_TTYPE
475 static void to_ttype(void)
477 /* Tell server we will (or won't) do TTYPE */
480 putiac2(WILL, TELOPT_TTYPE);
482 putiac2(WONT, TELOPT_TTYPE);
488 #ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
489 static void to_new_environ(void)
491 /* Tell server we will (or will not) do AUTOLOGIN */
494 putiac2(WILL, TELOPT_NEW_ENVIRON);
496 putiac2(WONT, TELOPT_NEW_ENVIRON);
502 #ifdef CONFIG_FEATURE_AUTOWIDTH
503 static void to_naws(void)
505 /* Tell server we will do NAWS */
506 putiac2(WILL, TELOPT_NAWS);
511 static void telopt(byte c)
515 case TELOPT_ECHO: to_echo(); break;
516 case TELOPT_SGA: to_sga(); break;
517 #ifdef CONFIG_FEATURE_TELNET_TTYPE
518 case TELOPT_TTYPE: to_ttype();break;
520 #ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
521 case TELOPT_NEW_ENVIRON: to_new_environ(); break;
523 #ifdef CONFIG_FEATURE_AUTOWIDTH
524 case TELOPT_NAWS: to_naws();
525 putiac_naws(c, win_width, win_height);
528 default: to_notsup(c);
534 /* ******************************* */
536 /* subnegotiation -- ignore all (except TTYPE,NAWS) */
538 static int subneg(byte c)
544 G.telstate = TS_SUB2;
545 #ifdef CONFIG_FEATURE_TELNET_TTYPE
547 if (c == TELOPT_TTYPE)
548 putiac_subopt(TELOPT_TTYPE,ttype);
550 #ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
552 if (c == TELOPT_NEW_ENVIRON)
553 putiac_subopt_autologin();
559 G.telstate = TS_SUB1;
565 /* ******************************* */
567 static void fgotsig(int sig)
573 static void rawmode(void)
575 if (G.do_termios) tcsetattr(0, TCSADRAIN, &G.termios_raw);
578 static void cookmode(void)
580 if (G.do_termios) tcsetattr(0, TCSADRAIN, &G.termios_def);
583 int telnet_main(int argc, char** argv);
584 int telnet_main(int argc, char** argv)
590 struct pollfd ufds[2];
596 #ifdef CONFIG_FEATURE_AUTOWIDTH
597 get_terminal_width_height(0, &win_width, &win_height);
600 #ifdef CONFIG_FEATURE_TELNET_TTYPE
601 ttype = getenv("TERM");
604 /* memset(&G, 0, sizeof G); - already is */
606 if (tcgetattr(0, &G.termios_def) >= 0) {
608 G.termios_raw = G.termios_def;
609 cfmakeraw(&G.termios_raw);
615 #ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
616 if (1 & getopt32(argc, argv, "al:", &autologin))
617 autologin = getenv("USER");
625 port = bb_lookup_port(*argv ? *argv++ : "telnet", "tcp", 23);
626 if (*argv) /* extra params?? */
629 G.netfd = create_and_connect_stream_or_die(host, port);
631 setsockopt(G.netfd, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1));
633 signal(SIGINT, fgotsig);
636 ufds[0].fd = 0; ufds[1].fd = G.netfd;
637 ufds[0].events = ufds[1].events = POLLIN;
641 FD_SET(G.netfd, &readfds);
647 fd_set rfds = readfds;
649 switch (select(maxfd, &rfds, NULL, NULL, NULL))
651 switch (poll(ufds, 2, -1))
657 /* error, ignore and/or log something, bay go to loop */
666 if (ufds[0].revents) /* well, should check POLLIN, but ... */
668 if (FD_ISSET(0, &rfds))
671 len = read(0, G.buf, DATABUFSIZE);
676 TRACE(0, ("Read con: %d\n", len));
678 handlenetoutput(len);
682 if (ufds[1].revents) /* well, should check POLLIN, but ... */
684 if (FD_ISSET(G.netfd, &rfds))
687 len = read(G.netfd, G.buf, DATABUFSIZE);
690 WriteCS(1, "Connection closed by foreign host.\r\n");
693 TRACE(0, ("Read netfd (%d): %d\n", G.netfd, len));