2 * $Id: telnet.c,v 1.3 2000/05/12 19:41:47 erik Exp $
3 * Mini telnet implementation for busybox
5 * Copyright (C) 2000 by Randolph Chung <tausq@debian.org>
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21 * This version of telnet is adapted (but very heavily modified) from the
22 * telnet in netkit-telnet 0.16, which is:
24 * Copyright (c) 1989 The Regents of the University of California.
25 * All rights reserved.
27 * Original copyright notice is retained at the end of this file.
39 #include <netinet/in.h>
40 #include <sys/types.h>
41 #include <sys/socket.h>
42 #include <sys/ioctl.h>
44 #include <arpa/telnet.h>
45 #include <arpa/inet.h>
48 static int STDOUT = 1;
49 static const char *telnet_usage = "telnet host [port]\n"
50 #ifndef BB_FEATURE_TRIVIAL_HELP
51 "\nProvides interactive communication with another\n"
52 "networked host using the TELNET protocol\n"
55 static struct termios saved_tc;
56 static unsigned char options[NTELOPTS];
57 static char tr_state = 0; /* telnet send and receive state */
58 static unsigned char subbuffer[256];
59 static unsigned char *subpointer, *subend;
60 #define SB_CLEAR() subpointer = subbuffer;
61 #define SB_TERM() { subend = subpointer; SB_CLEAR(); }
62 #define SB_ACCUM(c) if (subpointer < (subbuffer+sizeof subbuffer)) { *subpointer++ = (c); }
63 #define SB_GET() (*subpointer++)
64 #define SB_PEEK() (*subpointer)
65 #define SB_EOF() (subpointer >= subend)
66 #define SB_LEN() (subend - subpointer)
69 #define MASK_WILL 0x01
70 #define MASK_WONT 0x04
72 #define MASK_DONT 0x40
74 #define TFLAG_ISSET(opt, flag) (options[opt] & MASK_##flag)
75 #define TFLAG_SET(opt, flag) (options[opt] |= MASK_##flag)
76 #define TFLAG_CLR(opt, flag) (options[opt] &= ~MASK_##flag)
78 #define PERROR(ctx) do { fprintf(stderr, "%s: %s\n", ctx, strerror(errno)); \
88 #define TS_SB 7 /* sub-option collection */
89 #define TS_SE 8 /* looking for sub-option end */
92 static void telnet_init(void);
93 static void telnet_start(char *host, int port);
94 static void telnet_shutdown(void);
95 /* ******************************************************************* */
96 #define SENDCOMMAND(c,o) \
98 buf[0] = IAC; buf[1] = c; buf[2] = o; \
99 write(s, buf, sizeof(buf));
101 static inline void telnet_sendwill(int s, int c) { SENDCOMMAND(WILL, c); }
102 static inline void telnet_sendwont(int s, int c) { SENDCOMMAND(WONT, c); }
103 static inline void telnet_senddo(int s, int c) { SENDCOMMAND(DO, c); }
104 static inline void telnet_senddont(int s, int c) { SENDCOMMAND(DONT, c); }
106 static void telnet_setoptions(int s)
109 telnet_sendwill(s, TELOPT_NAWS); TFLAG_SET(TELOPT_NAWS, WILL);
110 telnet_sendwill(s, TELOPT_TSPEED); TFLAG_SET(TELOPT_TSPEED, WILL);
111 telnet_sendwill(s, TELOPT_NEW_ENVIRON); TFLAG_SET(TELOPT_NEW_ENVIRON, WILL);
112 telnet_senddo(s, TELOPT_STATUS); TFLAG_SET(TELOPT_STATUS, DO);
113 telnet_sendwill(s, TELOPT_TTYPE); TFLAG_SET(TELOPT_TTYPE, WILL);
115 telnet_senddo(s, TELOPT_SGA); TFLAG_SET(TELOPT_SGA, DO);
116 telnet_sendwill(s, TELOPT_LFLOW); TFLAG_SET(TELOPT_LFLOW, WILL);
117 telnet_sendwill(s, TELOPT_LINEMODE); TFLAG_SET(TELOPT_LINEMODE, WILL);
118 telnet_senddo(s, TELOPT_BINARY); TFLAG_SET(TELOPT_BINARY, DO);
119 telnet_sendwill(s, TELOPT_BINARY); TFLAG_SET(TELOPT_BINARY, WILL);
122 static void telnet_suboptions(int net)
127 if (TFLAG_ISSET(TELOPT_TTYPE, WONT)) return;
128 if (SB_EOF() || SB_GET() != TELQUAL_SEND) {
131 const char *name = getenv("TERM");
133 snprintf(buf, sizeof(buf), "%c%c%c%c%s%c%c", IAC, SB,
134 TELOPT_TTYPE, TELQUAL_IS, name, IAC, SE);
135 write(net, buf, strlen(name)+6);
140 if (TFLAG_ISSET(TELOPT_TSPEED, WONT)) return;
141 if (SB_EOF()) return;
142 if (SB_GET() == TELQUAL_SEND) {
144 long oospeed, iispeed;
145 netoring.printf("%c%c%c%c%ld,%ld%c%c", IAC, SB, TELOPT_TSPEED,
146 TELQUAL_IS, oospeed, iispeed, IAC, SE);
152 if (TFLAG_ISSET(TELOPT_LFLOW, WONT)) return;
153 if (SB_EOF()) return;
155 case 1: localflow = 1; break;
156 case 0: localflow = 0; break;
160 case TELOPT_LINEMODE:
161 if (TFLAG_ISSET(TELOPT_LINEMODE, WONT)) return;
162 if (SB_EOF()) return;
164 case WILL: lm_will(subpointer, SB_LEN()); break;
165 case WONT: lm_wont(subpointer, SB_LEN()); break;
166 case DO: lm_do(subpointer, SB_LEN()); break;
167 case DONT: lm_dont(subpointer, SB_LEN()); break;
168 case LM_SLC: slc(subpointer, SB_LEN()); break;
169 case LM_MODE: lm_mode(subpointer, SB_LEN(), 0); break;
174 if (SB_EOF()) return;
178 if (TFLAG_ISSET(TELOPT_ENVIRON, DONT)) return;
181 if (TFLAG_ISSET(TELOPT_ENVIRON, WONT)) return;
186 env_opt(subpointer, SB_LEN());
189 case TELOPT_XDISPLOC:
190 if (TFLAG_ISSET(TELOPT_XDISPLOC, WONT)) return;
191 if (SB_EOF()) return;
192 if (SB_GET() == TELQUAL_SEND) {
193 const char *dp = getenv("DISPLAY");
195 snprintf(buf, sizeof(buf), "%c%c%c%c%s%c%c", IAC, SB,
196 TELOPT_XDISPLOC, TELQUAL_IS, dp, IAC, SE);
197 write(net, buf, strlen(dp)+6);
206 static void sighandler(int sig)
212 static int telnet_send(int tty, int net)
217 while ((ret = read(tty, &ch, 1)) > 0) {
218 if (ch == 29) { /* 29 -- ctrl-] */
219 /* do something here? */
222 ret = write(net, &ch, 1);
226 if (ret == -1 && errno == EWOULDBLOCK) return 1;
230 static int telnet_recv(int net, int tty)
232 /* globals: tr_state - telnet receive state */
236 while ((ret = read(net, &ch, 1)) > 0) {
238 /* printf("%02X ", c); fflush(stdout); */
251 tr_state = TS_WILL; break;
253 tr_state = TS_WONT; break;
255 tr_state = TS_DO; break;
257 tr_state = TS_DONT; break;
260 tr_state = TS_SB; break;
262 write(tty, &c, 1); /* fallthrough */
267 /* subnegotiation -- ignored for now */
269 if (c == IAC) tr_state = TS_SE;
276 } else if (c == SE) {
281 telnet_suboptions(net);
284 /* otherwise this is an error, but we ignore it for now */
286 /* handle incoming requests */
288 printf("WILL %s\n", telopts[c]);
289 if (!TFLAG_ISSET(c, DO)) {
290 if (c == TELOPT_BINARY) {
293 telnet_senddo(net, c);
296 telnet_senddont(net, c);
299 telnet_senddont(net, c);
303 printf("WONT %s\n", telopts[c]);
304 if (!TFLAG_ISSET(c, DONT)) {
307 telnet_senddont(net, c);
312 printf("DO %s\n", telopts[c]);
313 if (!TFLAG_ISSET(c, WILL)) {
314 if (c == TELOPT_BINARY) {
317 telnet_sendwill(net, c);
320 telnet_sendwont(net, c);
326 printf("DONT %s\n", telopts[c]);
327 if (!TFLAG_ISSET(c, WONT)) {
330 telnet_sendwont(net, c);
337 if (ret == -1 && errno == EWOULDBLOCK) return 1;
341 /* ******************************************************************* */
342 static void telnet_init(void)
344 struct termios tmp_tc;
345 cc_t esc = (']' & 0x1f); /* ctrl-] */
347 memset(options, 0, sizeof(options));
350 tcgetattr(STDIN, &saved_tc);
353 tmp_tc.c_lflag &= ~ECHO; /* echo */
354 tmp_tc.c_oflag |= ONLCR; /* NL->CRLF translation */
355 tmp_tc.c_iflag |= ICRNL;
356 tmp_tc.c_iflag &= ~(IXANY|IXOFF|IXON); /* no flow control */
357 tmp_tc.c_lflag |= ISIG; /* trap signals */
358 tmp_tc.c_lflag &= ~ICANON; /* edit mode */
360 /* misc settings, compat with default telnet stuff */
361 tmp_tc.c_oflag &= ~TABDLY;
364 tmp_tc.c_iflag &= ~ISTRIP;
365 tmp_tc.c_cflag &= ~(CSIZE|PARENB);
366 tmp_tc.c_cflag |= saved_tc.c_cflag & (CSIZE|PARENB);
367 tmp_tc.c_oflag |= OPOST;
369 /* set escape character */
370 tmp_tc.c_cc[VEOL] = esc;
371 tcsetattr(STDIN, TCSADRAIN, &tmp_tc);
374 static void telnet_start(char *hostname, int port)
376 struct hostent *host = 0;
377 struct sockaddr_in addr;
381 memset(&addr, 0, sizeof(addr));
382 host = gethostbyname(hostname);
384 fprintf(stderr, "Unknown host: %s\n", hostname);
387 addr.sin_family = host->h_addrtype;
388 memcpy(&addr.sin_addr, host->h_addr, sizeof(addr.sin_addr));
389 addr.sin_port = htons(port);
391 printf("Trying %s...\n", inet_ntoa(addr.sin_addr));
393 if ((s = socket(AF_INET, SOCK_STREAM, 0)) < 0) PERROR("socket");
394 if (connect(s, (struct sockaddr *)&addr, sizeof(addr)) < 0)
396 printf("Connected to %s\n", hostname);
397 printf("Escape character is ^]\n");
399 signal(SIGINT, sighandler);
400 signal(SIGQUIT, sighandler);
401 signal(SIGPIPE, sighandler);
402 signal(SIGWINCH, sighandler);
404 /* make inputs nonblocking */
406 ioctl(s, FIONBIO, &c);
407 ioctl(STDIN, FIONBIO, &c);
409 if (port == TELNETPORT) telnet_setoptions(s);
411 /* shuttle data back and forth between tty and socket */
417 /* FD_SET(s, &wfds); */
418 FD_SET(STDIN, &rfds);
419 /* FD_SET(STDOUT, &wfds); */
421 if ((c = select(s+1, &rfds, &wfds, 0, 0))) {
426 if (FD_ISSET(s, &rfds)) {
427 /* input from network */
429 c = telnet_recv(s, STDOUT);
431 if (c < 0) PERROR("telnet_recv");
433 if (FD_ISSET(STDIN, &rfds)) {
435 FD_CLR(STDIN, &rfds);
436 c = telnet_send(STDIN, s);
438 if (c < 0) PERROR("telnet_send");
446 static void telnet_shutdown(void)
449 tcsetattr(STDIN, TCSANOW, &saved_tc);
452 #ifdef STANDALONE_TELNET
453 void usage(const char *msg)
459 int main(int argc, char **argv)
461 int telnet_main(int argc, char **argv)
464 int port = TELNETPORT;
467 if (argc < 1) usage(telnet_usage);
468 if (argc > 1) port = atoi(argv[1]);
470 atexit(telnet_shutdown);
472 telnet_start(argv[0], port);
477 * Copyright (c) 1988, 1990 Regents of the University of California.
478 * All rights reserved.
480 * Redistribution and use in source and binary forms, with or without
481 * modification, are permitted provided that the following conditions
483 * 1. Redistributions of source code must retain the above copyright
484 * notice, this list of conditions and the following disclaimer.
485 * 2. Redistributions in binary form must reproduce the above copyright
486 * notice, this list of conditions and the following disclaimer in the
487 * documentation and/or other materials provided with the distribution.
488 * 3. All advertising materials mentioning features or use of this software
489 * must display the following acknowledgement:
490 * This product includes software developed by the University of
491 * California, Berkeley and its contributors.
492 * 4. Neither the name of the University nor the names of its contributors
493 * may be used to endorse or promote products derived from this software
494 * without specific prior written permission.
496 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
497 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
498 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
499 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
500 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
501 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
502 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
503 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
504 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
505 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF