1 /* vi: set sw=4 ts=4: */
3 * $Id: telnet.c,v 1.1 2000/02/22 17:17:45 erik Exp $
4 * Mini telnet implementation for busybox
6 * Copyright (C) 2000 by Randolph Chung <tausq@debian.org>
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
22 * This version of telnet is adapted (but very heavily modified) from the
23 * telnet in netkit-telnet 0.16, which is:
25 * Copyright (c) 1989 The Regents of the University of California.
26 * All rights reserved.
28 * Original copyright notice is retained at the end of this file.
40 #include <netinet/in.h>
41 #include <sys/types.h>
42 #include <sys/socket.h>
43 #include <sys/ioctl.h>
45 #include <arpa/telnet.h>
46 #include <arpa/inet.h>
49 static int STDOUT = 1;
50 static const char *telnet_usage = "telnet host [port]\n\n";
51 static struct termios saved_tc;
52 static unsigned char options[NTELOPTS];
53 static char tr_state = 0; /* telnet send and receive state */
54 static unsigned char subbuffer[256];
55 static unsigned char *subpointer, *subend;
56 #define SB_CLEAR() subpointer = subbuffer;
57 #define SB_TERM() { subend = subpointer; SB_CLEAR(); }
58 #define SB_ACCUM(c) if (subpointer < (subbuffer+sizeof subbuffer)) { *subpointer++ = (c); }
59 #define SB_GET() (*subpointer++)
60 #define SB_PEEK() (*subpointer)
61 #define SB_EOF() (subpointer >= subend)
62 #define SB_LEN() (subend - subpointer)
65 #define MASK_WILL 0x01
66 #define MASK_WONT 0x04
68 #define MASK_DONT 0x40
70 #define TFLAG_ISSET(opt, flag) (options[opt] & MASK_##flag)
71 #define TFLAG_SET(opt, flag) (options[opt] |= MASK_##flag)
72 #define TFLAG_CLR(opt, flag) (options[opt] &= ~MASK_##flag)
74 #define PERROR(ctx) do { fprintf(stderr, "%s: %s\n", ctx, strerror(errno)); \
84 #define TS_SB 7 /* sub-option collection */
85 #define TS_SE 8 /* looking for sub-option end */
88 static void telnet_init(void);
89 static void telnet_start(char *host, int port);
90 static void telnet_shutdown(void);
91 /* ******************************************************************* */
92 #define SENDCOMMAND(c,o) \
94 buf[0] = IAC; buf[1] = c; buf[2] = o; \
95 write(s, buf, sizeof(buf));
97 static inline void telnet_sendwill(int s, int c) { SENDCOMMAND(WILL, c); }
98 static inline void telnet_sendwont(int s, int c) { SENDCOMMAND(WONT, c); }
99 static inline void telnet_senddo(int s, int c) { SENDCOMMAND(DO, c); }
100 static inline void telnet_senddont(int s, int c) { SENDCOMMAND(DONT, c); }
102 static void telnet_setoptions(int s)
105 telnet_senddo(s, TELOPT_SGA); TFLAG_SET(TELOPT_SGA, DO);
106 telnet_sendwill(s, TELOPT_NAWS); TFLAG_SET(TELOPT_NAWS, WILL);
107 telnet_sendwill(s, TELOPT_TSPEED); TFLAG_SET(TELOPT_TSPEED, WILL);
108 telnet_sendwill(s, TELOPT_LFLOW); TFLAG_SET(TELOPT_LFLOW, WILL);
109 telnet_sendwill(s, TELOPT_LINEMODE); TFLAG_SET(TELOPT_LINEMODE, WILL);
110 telnet_sendwill(s, TELOPT_NEW_ENVIRON); TFLAG_SET(TELOPT_NEW_ENVIRON, WILL);
111 telnet_senddo(s, TELOPT_STATUS); TFLAG_SET(TELOPT_STATUS, DO);
112 telnet_sendwill(s, TELOPT_TTYPE); TFLAG_SET(TELOPT_TTYPE, WILL);
114 telnet_senddo(s, TELOPT_BINARY); TFLAG_SET(TELOPT_BINARY, DO);
115 telnet_sendwill(s, TELOPT_BINARY); TFLAG_SET(TELOPT_BINARY, WILL);
118 static void telnet_suboptions(int net)
123 if (TFLAG_ISSET(TELOPT_TTYPE, WONT)) return;
124 if (SB_EOF() || SB_GET() != TELQUAL_SEND) {
127 const char *name = getenv("TERM");
129 snprintf(buf, sizeof(buf), "%c%c%c%c%s%c%c", IAC, SB,
130 TELOPT_TTYPE, TELQUAL_IS, name, IAC, SE);
131 write(net, buf, strlen(name)+6);
136 if (TFLAG_ISSET(TELOPT_TSPEED, WONT)) return;
137 if (SB_EOF()) return;
138 if (SB_GET() == TELQUAL_SEND) {
140 long oospeed, iispeed;
141 netoring.printf("%c%c%c%c%ld,%ld%c%c", IAC, SB, TELOPT_TSPEED,
142 TELQUAL_IS, oospeed, iispeed, IAC, SE);
148 if (TFLAG_ISSET(TELOPT_LFLOW, WONT)) return;
149 if (SB_EOF()) return;
151 case 1: localflow = 1; break;
152 case 0: localflow = 0; break;
156 case TELOPT_LINEMODE:
157 if (TFLAG_ISSET(TELOPT_LINEMODE, WONT)) return;
158 if (SB_EOF()) return;
160 case WILL: lm_will(subpointer, SB_LEN()); break;
161 case WONT: lm_wont(subpointer, SB_LEN()); break;
162 case DO: lm_do(subpointer, SB_LEN()); break;
163 case DONT: lm_dont(subpointer, SB_LEN()); break;
164 case LM_SLC: slc(subpointer, SB_LEN()); break;
165 case LM_MODE: lm_mode(subpointer, SB_LEN(), 0); break;
170 if (SB_EOF()) return;
174 if (TFLAG_ISSET(TELOPT_ENVIRON, DONT)) return;
177 if (TFLAG_ISSET(TELOPT_ENVIRON, WONT)) return;
182 env_opt(subpointer, SB_LEN());
185 case TELOPT_XDISPLOC:
186 if (TFLAG_ISSET(TELOPT_XDISPLOC, WONT)) return;
187 if (SB_EOF()) return;
188 if (SB_GET() == TELQUAL_SEND) {
189 const char *dp = getenv("DISPLAY");
191 snprintf(buf, sizeof(buf), "%c%c%c%c%s%c%c", IAC, SB,
192 TELOPT_XDISPLOC, TELQUAL_IS, dp, IAC, SE);
193 write(net, buf, strlen(dp)+6);
202 static void sighandler(int sig)
208 static int telnet_send(int tty, int net)
213 while ((ret = read(tty, &ch, 1)) > 0) {
214 if (ch == 29) { /* 29 -- ctrl-] */
215 /* do something here? */
218 ret = write(net, &ch, 1);
222 if (ret == -1 && errno == EWOULDBLOCK) return 1;
226 static int telnet_recv(int net, int tty)
228 /* globals: tr_state - telnet receive state */
232 while ((ret = read(net, &ch, 1)) > 0) {
234 /* printf("%02X ", c); fflush(stdout); */
247 tr_state = TS_WILL; break;
249 tr_state = TS_WONT; break;
251 tr_state = TS_DO; break;
253 tr_state = TS_DONT; break;
256 tr_state = TS_SB; break;
258 write(tty, &c, 1); /* fallthrough */
263 /* subnegotiation -- ignored for now */
265 if (c == IAC) tr_state = TS_SE;
272 } else if (c == SE) {
277 telnet_suboptions(net);
280 /* otherwise this is an error, but we ignore it for now */
282 /* handle incoming requests */
284 printf("WILL %s\n", telopts[c]);
285 if (!TFLAG_ISSET(c, DO)) {
286 if (c == TELOPT_BINARY) {
289 telnet_senddo(net, c);
292 telnet_senddont(net, c);
295 telnet_senddont(net, c);
299 printf("WONT %s\n", telopts[c]);
300 if (!TFLAG_ISSET(c, DONT)) {
303 telnet_senddont(net, c);
308 printf("DO %s\n", telopts[c]);
309 if (!TFLAG_ISSET(c, WILL)) {
310 if (c == TELOPT_BINARY) {
313 telnet_sendwill(net, c);
316 telnet_sendwont(net, c);
322 printf("DONT %s\n", telopts[c]);
323 if (!TFLAG_ISSET(c, WONT)) {
326 telnet_sendwont(net, c);
333 if (ret == -1 && errno == EWOULDBLOCK) return 1;
337 /* ******************************************************************* */
338 static void telnet_init(void)
340 struct termios tmp_tc;
341 cc_t esc = (']' & 0x1f); /* ctrl-] */
343 memset(options, 0, sizeof(options));
346 tcgetattr(STDIN, &saved_tc);
349 tmp_tc.c_lflag &= ~ECHO; /* echo */
350 tmp_tc.c_oflag |= ONLCR; /* NL->CRLF translation */
351 tmp_tc.c_iflag |= ICRNL;
352 tmp_tc.c_iflag &= ~(IXANY|IXOFF|IXON); /* no flow control */
353 tmp_tc.c_lflag |= ISIG; /* trap signals */
354 tmp_tc.c_lflag &= ~ICANON; /* edit mode */
356 /* misc settings, compat with default telnet stuff */
357 tmp_tc.c_oflag &= ~TABDLY;
360 tmp_tc.c_iflag &= ~ISTRIP;
361 tmp_tc.c_cflag &= ~(CSIZE|PARENB);
362 tmp_tc.c_cflag |= saved_tc.c_cflag & (CSIZE|PARENB);
363 tmp_tc.c_oflag |= OPOST;
365 /* set escape character */
366 tmp_tc.c_cc[VEOL] = esc;
367 tcsetattr(STDIN, TCSADRAIN, &tmp_tc);
370 static void telnet_start(char *hostname, int port)
372 struct hostent *host = 0;
373 struct sockaddr_in addr;
377 memset(&addr, 0, sizeof(addr));
378 host = gethostbyname(hostname);
380 fprintf(stderr, "Unknown host: %s\n", hostname);
383 addr.sin_family = host->h_addrtype;
384 memcpy(&addr.sin_addr, host->h_addr, sizeof(addr.sin_addr));
385 addr.sin_port = htons(port);
387 printf("Trying %s...\n", inet_ntoa(addr.sin_addr));
389 if ((s = socket(AF_INET, SOCK_STREAM, 0)) < 0) PERROR("socket");
390 if (connect(s, (struct sockaddr *)&addr, sizeof(addr)) < 0)
392 printf("Connected to %s\n", hostname);
393 printf("Escape character is ^]\n");
395 signal(SIGINT, sighandler);
396 signal(SIGQUIT, sighandler);
397 signal(SIGPIPE, sighandler);
398 signal(SIGWINCH, sighandler);
400 /* make inputs nonblocking */
402 ioctl(s, FIONBIO, &c);
403 ioctl(STDIN, FIONBIO, &c);
405 if (port == TELNETPORT) telnet_setoptions(s);
407 /* shuttle data back and forth between tty and socket */
413 /* FD_SET(s, &wfds); */
414 FD_SET(STDIN, &rfds);
415 /* FD_SET(STDOUT, &wfds); */
417 if ((c = select(s+1, &rfds, &wfds, 0, 0))) {
422 if (FD_ISSET(s, &rfds)) {
423 /* input from network */
425 c = telnet_recv(s, STDOUT);
427 if (c < 0) PERROR("telnet_recv");
429 if (FD_ISSET(STDIN, &rfds)) {
431 FD_CLR(STDIN, &rfds);
432 c = telnet_send(STDIN, s);
434 if (c < 0) PERROR("telnet_send");
442 static void telnet_shutdown(void)
445 tcsetattr(STDIN, TCSANOW, &saved_tc);
448 #ifdef STANDALONE_TELNET
449 void usage(const char *msg)
455 int main(int argc, char **argv)
457 int telnet_main(int argc, char **argv)
460 int port = TELNETPORT;
463 if (argc < 1) usage(telnet_usage);
464 if (argc > 1) port = atoi(argv[1]);
466 atexit(telnet_shutdown);
468 telnet_start(argv[0], port);
473 * Copyright (c) 1988, 1990 Regents of the University of California.
474 * All rights reserved.
476 * Redistribution and use in source and binary forms, with or without
477 * modification, are permitted provided that the following conditions
479 * 1. Redistributions of source code must retain the above copyright
480 * notice, this list of conditions and the following disclaimer.
481 * 2. Redistributions in binary form must reproduce the above copyright
482 * notice, this list of conditions and the following disclaimer in the
483 * documentation and/or other materials provided with the distribution.
484 * 3. All advertising materials mentioning features or use of this software
485 * must display the following acknowledgement:
486 * This product includes software developed by the University of
487 * California, Berkeley and its contributors.
488 * 4. Neither the name of the University nor the names of its contributors
489 * may be used to endorse or promote products derived from this software
490 * without specific prior written permission.
492 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
493 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
494 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
495 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
496 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
497 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
498 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
499 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
500 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
501 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF