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 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License as published by
13 * the Free Software Foundation; either version 2 of the License, or
14 * (at your option) any later version.
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19 * General Public License for more details.
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software
23 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
26 * Revision 3.1 1994/04/17 11:31:54 too
28 * Modified 2000/06/13 for inclusion into BusyBox by Erik Andersen
29 * <andersen@lineo.com>
33 #warning This applet has moved to netkit-tiny. After BusyBox 0.49, this
34 #warning applet will be removed from BusyBox. All maintenance efforts
35 #warning should be done in the netkit-tiny source tree.
46 #include <arpa/telnet.h>
47 #include <sys/types.h>
48 #include <sys/socket.h>
49 #include <netinet/in.h>
53 static const int DOTRACE = 1;
57 #include <arpa/inet.h> /* for inet_ntoa()... */
58 #define TRACE(x, y) do { if (x) printf y; } while (0)
70 static const int DATABUFSIZE = 128;
71 static const int IACBUFSIZE = 128;
73 static const int CHM_TRY = 0;
74 static const int CHM_ON = 1;
75 static const int CHM_OFF = 2;
77 static const int UF_ECHO = 0x01;
78 static const int UF_SGA = 0x02;
88 #define WriteCS(fd, str) write(fd, str, sizeof str -1)
90 typedef unsigned char byte;
92 /* use globals to reduce size ??? */ /* test this hypothesis later */
94 int netfd; /* console fd:s are 0 and 1 (and 2) */
95 /* same buffer used both for network and console read/write */
96 char * buf; /* allocating so static size is smaller */
98 byte telstate; /* telnet negotiation state from network input */
99 byte telwish; /* DO, DONT, WILL, WONT */
103 /* buffer to handle telnet negotiations */
105 short iaclen; /* could even use byte */
106 struct termios termios_def;
107 struct termios termios_raw;
110 #define xUSE_GLOBALVAR_PTR /* xUSE... -> don't use :D (makes smaller code) */
112 #ifdef USE_GLOBALVAR_PTR
113 struct Globalvars * Gptr;
119 static inline void iacflush()
121 write(G.netfd, G.iacbuf, G.iaclen);
125 /* Function prototypes */
126 static int getport(char * p);
127 static struct in_addr getserver(char * p);
128 static int create_socket();
129 static void setup_sockaddr_in(struct sockaddr_in * addr, int port);
130 static int remote_connect(struct in_addr addr, int port);
131 static void rawmode();
132 static void cookmode();
133 static void do_linemode();
134 static void will_charmode();
135 static void telopt(byte c);
136 static int subneg(byte c);
138 static int local_bind(int port);
144 static void doexit(int ev)
150 static void conescape()
154 if (G.gotsig) /* came from line mode... go raw */
157 WriteCS(1, "\r\nConsole escape. Commands are:\r\n\n"
158 " l go to line mode\r\n"
159 " c go to character mode\r\n"
160 " z suspend telnet\r\n"
161 " e exit telnet\r\n");
163 if (read(0, &b, 1) <= 0)
191 WriteCS(1, "continuing...\r\n");
200 static void handlenetoutput()
202 /* here we could do smart tricks how to handle 0xFF:s in output
203 * stream like writing twice every sequence of FF:s (thus doing
204 * many write()s. But I think interactive telnet application does
205 * not need to be 100% 8-bit clean, so changing every 0xff:s to
211 for (i = G.len; i > 0; i--, p++)
221 write(G.netfd, G.buf, G.len);
225 static void handlenetinput()
230 for (i = 0; i < G.len; i++)
234 if (G.telstate == 0) /* most of the time state == 0 */
253 if (c == IAC) /* IAC IAC -> 0xFF */
263 G.telstate = TS_SUB1;
273 G.telstate = TS_0; /* DATA MARK must be added later */
276 case TS_OPT: /* WILL, WONT, DO, DONT */
280 case TS_SUB1: /* Subnegotiation */
281 case TS_SUB2: /* Subnegotiation */
282 if (subneg(c) == TRUE)
289 if (G.iaclen) iacflush();
290 if (G.telstate == TS_0) G.telstate = 0;
296 write(1, G.buf, G.len);
300 /* ******************************* */
302 static inline void putiac(int c)
304 G.iacbuf[G.iaclen++] = c;
308 static void putiac2(byte wwdd, byte c)
310 if (G.iaclen + 3 > IACBUFSIZE)
319 static void putiac1(byte c)
321 if (G.iaclen + 2 > IACBUFSIZE)
329 /* void putiacstring (subneg strings) */
331 /* ******************************* */
333 char const escapecharis[] = "\r\nEscape character is ";
335 static void setConMode()
337 if (G.telflags & UF_ECHO)
339 if (G.charmode == CHM_TRY) {
341 printf("\r\nEntering character mode%s'^]'.\r\n", escapecharis);
347 if (G.charmode != CHM_OFF) {
348 G.charmode = CHM_OFF;
349 printf("\r\nEntering line mode%s'^C'.\r\n", escapecharis);
355 /* ******************************* */
357 static void will_charmode()
359 G.charmode = CHM_TRY;
360 G.telflags |= (UF_ECHO | UF_SGA);
363 putiac2(DO, TELOPT_ECHO);
364 putiac2(DO, TELOPT_SGA);
368 static void do_linemode()
370 G.charmode = CHM_TRY;
371 G.telflags &= ~(UF_ECHO | UF_SGA);
374 putiac2(DONT, TELOPT_ECHO);
375 putiac2(DONT, TELOPT_SGA);
379 /* ******************************* */
381 static inline void to_notsup(char c)
383 if (G.telwish == WILL) putiac2(DONT, c);
384 else if (G.telwish == DO) putiac2(WONT, c);
387 static inline void to_echo()
389 /* if server requests ECHO, don't agree */
390 if (G.telwish == DO) { putiac2(WONT, TELOPT_ECHO); return; }
391 else if (G.telwish == DONT) return;
393 if (G.telflags & UF_ECHO)
395 if (G.telwish == WILL)
399 if (G.telwish == WONT)
402 if (G.charmode != CHM_OFF)
403 G.telflags ^= UF_ECHO;
405 if (G.telflags & UF_ECHO)
406 putiac2(DO, TELOPT_ECHO);
408 putiac2(DONT, TELOPT_ECHO);
411 WriteCS(1, "\r\n"); /* sudden modec */
414 static inline void to_sga()
416 /* daemon always sends will/wont, client do/dont */
418 if (G.telflags & UF_SGA)
420 if (G.telwish == WILL)
424 if (G.telwish == WONT)
427 if ((G.telflags ^= UF_SGA) & UF_SGA) /* toggle */
428 putiac2(DO, TELOPT_SGA);
430 putiac2(DONT, TELOPT_SGA);
435 static void telopt(byte c)
439 case TELOPT_ECHO: to_echo(c); break;
440 case TELOPT_SGA: to_sga(c); break;
441 default: to_notsup(c); break;
446 /* ******************************* */
448 /* subnegotiation -- ignore all */
450 static int subneg(byte c)
456 G.telstate = TS_SUB2;
461 G.telstate = TS_SUB1;
467 /* ******************************* */
469 static void fgotsig(int sig)
475 static void rawmode()
477 tcsetattr(0, TCSADRAIN, &G.termios_raw);
480 static void cookmode()
482 tcsetattr(0, TCSADRAIN, &G.termios_def);
485 extern int telnet_main(int argc, char** argv)
490 struct pollfd ufds[2];
497 memset(&G, 0, sizeof G);
499 if (tcgetattr(0, &G.termios_def) < 0)
502 G.termios_raw = G.termios_def;
504 cfmakeraw(&G.termios_raw);
506 if (argc < 2) usage(telnet_usage);
507 port = (argc > 2)? getport(argv[2]): 23;
509 G.buf = xmalloc(DATABUFSIZE);
510 G.iacbuf = xmalloc(IACBUFSIZE);
512 host = getserver(argv[1]);
514 G.netfd = remote_connect(host, port);
516 signal(SIGINT, fgotsig);
519 ufds[0].fd = 0; ufds[1].fd = G.netfd;
520 ufds[0].events = ufds[1].events = POLLIN;
524 FD_SET(G.netfd, &readfds);
531 fd_set rfds = readfds;
533 switch (select(maxfd, &rfds, NULL, NULL, NULL))
535 switch (poll(ufds, 2, -1))
541 /* error, ignore and/or log something, bay go to loop */
550 if (ufds[0].revents) /* well, should check POLLIN, but ... */
552 if (FD_ISSET(0, &rfds))
555 G.len = read(0, G.buf, DATABUFSIZE);
560 TRACE(0, ("Read con: %d\n", G.len));
566 if (ufds[1].revents) /* well, should check POLLIN, but ... */
568 if (FD_ISSET(G.netfd, &rfds))
571 G.len = read(G.netfd, G.buf, DATABUFSIZE);
575 WriteCS(1, "Connection closed by foreign host.\r\n");
578 TRACE(0, ("Read netfd (%d): %d\n", G.netfd, G.len));
586 static int getport(char * p)
588 unsigned int port = atoi(p);
590 if ((unsigned)(port - 1 ) > 65534)
592 error_msg_and_die("%s: bad port number\n", p);
597 static struct in_addr getserver(char * host)
602 if ((he = gethostbyname(host)) == NULL)
604 error_msg_and_die("%s: Unknown host\n", host);
606 memcpy(&addr, he->h_addr, sizeof addr);
608 TRACE(1, ("addr: %s\n", inet_ntoa(addr)));
613 static int create_socket()
615 return socket(AF_INET, SOCK_STREAM, 0);
618 static void setup_sockaddr_in(struct sockaddr_in * addr, int port)
620 memset(addr, 0, sizeof addr);
621 addr->sin_family = AF_INET;
622 addr->sin_port = htons(port);
626 static int local_bind(int port)
628 struct sockaddr_in s_addr;
629 int s = create_socket();
631 setup_sockaddr_in(&s_addr, port);
633 setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &one, sizeof one);
635 if (bind(s, &s_addr, sizeof s_addr) < 0)
637 char * e = sys_errlist[errno];
638 syserrorexit("bind");
647 static int remote_connect(struct in_addr addr, int port)
649 struct sockaddr_in s_addr;
650 int s = create_socket();
652 setup_sockaddr_in(&s_addr, port);
653 s_addr.sin_addr = addr;
655 setsockopt(s, SOL_SOCKET, SO_KEEPALIVE, &one, sizeof one);
657 if (connect(s, (struct sockaddr *)&s_addr, sizeof s_addr) < 0)
659 perror_msg_and_die("Unable to connect to remote host");
666 c-file-style: "linux"