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>
40 #include <arpa/telnet.h>
41 #include <sys/types.h>
42 #include <sys/socket.h>
43 #include <netinet/in.h>
48 static const int DOTRACE = 1;
52 #include <arpa/inet.h> /* for inet_ntoa()... */
53 #define TRACE(x, y) do { if (x) printf y; } while (0)
65 static const int DATABUFSIZE = 128;
66 static const int IACBUFSIZE = 128;
68 static const int CHM_TRY = 0;
69 static const int CHM_ON = 1;
70 static const int CHM_OFF = 2;
72 static const int UF_ECHO = 0x01;
73 static const int UF_SGA = 0x02;
83 #define WriteCS(fd, str) write(fd, str, sizeof str -1)
85 typedef unsigned char byte;
87 /* use globals to reduce size ??? */ /* test this hypothesis later */
89 int netfd; /* console fd:s are 0 and 1 (and 2) */
90 /* same buffer used both for network and console read/write */
91 char * buf; /* allocating so static size is smaller */
93 byte telstate; /* telnet negotiation state from network input */
94 byte telwish; /* DO, DONT, WILL, WONT */
98 /* buffer to handle telnet negotiations */
100 short iaclen; /* could even use byte */
101 struct termios termios_def;
102 struct termios termios_raw;
105 #define xUSE_GLOBALVAR_PTR /* xUSE... -> don't use :D (makes smaller code) */
107 #ifdef USE_GLOBALVAR_PTR
108 struct Globalvars * Gptr;
114 static inline void iacflush()
116 write(G.netfd, G.iacbuf, G.iaclen);
120 /* Function prototypes */
121 static int getport(char * p);
122 static struct in_addr getserver(char * p);
123 static int create_socket();
124 static void setup_sockaddr_in(struct sockaddr_in * addr, int port);
125 static int remote_connect(struct in_addr addr, int port);
126 static void rawmode();
127 static void cookmode();
128 static void do_linemode();
129 static void will_charmode();
130 static void telopt(byte c);
131 static int subneg(byte c);
133 static int local_bind(int port);
139 static void doexit(int ev)
145 static void conescape()
149 if (G.gotsig) /* came from line mode... go raw */
152 WriteCS(1, "\r\nConsole escape. Commands are:\r\n\n"
153 " l go to line mode\r\n"
154 " c go to character mode\r\n"
155 " z suspend telnet\r\n"
156 " e exit telnet\r\n");
158 if (read(0, &b, 1) <= 0)
186 WriteCS(1, "continuing...\r\n");
195 static void handlenetoutput()
197 /* here we could do smart tricks how to handle 0xFF:s in output
198 * stream like writing twice every sequence of FF:s (thus doing
199 * many write()s. But I think interactive telnet application does
200 * not need to be 100% 8-bit clean, so changing every 0xff:s to
206 for (i = G.len; i > 0; i--, p++)
216 write(G.netfd, G.buf, G.len);
220 static void handlenetinput()
225 for (i = 0; i < G.len; i++)
229 if (G.telstate == 0) /* most of the time state == 0 */
248 if (c == IAC) /* IAC IAC -> 0xFF */
258 G.telstate = TS_SUB1;
268 G.telstate = TS_0; /* DATA MARK must be added later */
271 case TS_OPT: /* WILL, WONT, DO, DONT */
275 case TS_SUB1: /* Subnegotiation */
276 case TS_SUB2: /* Subnegotiation */
277 if (subneg(c) == TRUE)
284 if (G.iaclen) iacflush();
285 if (G.telstate == TS_0) G.telstate = 0;
291 write(1, G.buf, G.len);
295 /* ******************************* */
297 static inline void putiac(int c)
299 G.iacbuf[G.iaclen++] = c;
303 static void putiac2(byte wwdd, byte c)
305 if (G.iaclen + 3 > IACBUFSIZE)
314 static void putiac1(byte c)
316 if (G.iaclen + 2 > IACBUFSIZE)
324 /* void putiacstring (subneg strings) */
326 /* ******************************* */
328 char const escapecharis[] = "\r\nEscape character is ";
330 static void setConMode()
332 if (G.telflags & UF_ECHO)
334 if (G.charmode == CHM_TRY) {
336 printf("\r\nEntering character mode%s'^]'.\r\n", escapecharis);
342 if (G.charmode != CHM_OFF) {
343 G.charmode = CHM_OFF;
344 printf("\r\nEntering line mode%s'^C'.\r\n", escapecharis);
350 /* ******************************* */
352 static void will_charmode()
354 G.charmode = CHM_TRY;
355 G.telflags |= (UF_ECHO | UF_SGA);
358 putiac2(DO, TELOPT_ECHO);
359 putiac2(DO, TELOPT_SGA);
363 static void do_linemode()
365 G.charmode = CHM_TRY;
366 G.telflags &= ~(UF_ECHO | UF_SGA);
369 putiac2(DONT, TELOPT_ECHO);
370 putiac2(DONT, TELOPT_SGA);
374 /* ******************************* */
376 static inline void to_notsup(char c)
378 if (G.telwish == WILL) putiac2(DONT, c);
379 else if (G.telwish == DO) putiac2(WONT, c);
382 static inline void to_echo()
384 /* if server requests ECHO, don't agree */
385 if (G.telwish == DO) { putiac2(WONT, TELOPT_ECHO); return; }
386 else if (G.telwish == DONT) return;
388 if (G.telflags & UF_ECHO)
390 if (G.telwish == WILL)
394 if (G.telwish == WONT)
397 if (G.charmode != CHM_OFF)
398 G.telflags ^= UF_ECHO;
400 if (G.telflags & UF_ECHO)
401 putiac2(DO, TELOPT_ECHO);
403 putiac2(DONT, TELOPT_ECHO);
406 WriteCS(1, "\r\n"); /* sudden modec */
409 static inline void to_sga()
411 /* daemon always sends will/wont, client do/dont */
413 if (G.telflags & UF_SGA)
415 if (G.telwish == WILL)
419 if (G.telwish == WONT)
422 if ((G.telflags ^= UF_SGA) & UF_SGA) /* toggle */
423 putiac2(DO, TELOPT_SGA);
425 putiac2(DONT, TELOPT_SGA);
430 static void telopt(byte c)
434 case TELOPT_ECHO: to_echo(c); break;
435 case TELOPT_SGA: to_sga(c); break;
436 default: to_notsup(c); break;
441 /* ******************************* */
443 /* subnegotiation -- ignore all */
445 static int subneg(byte c)
451 G.telstate = TS_SUB2;
456 G.telstate = TS_SUB1;
462 /* ******************************* */
464 static void fgotsig(int sig)
470 static void rawmode()
472 tcsetattr(0, TCSADRAIN, &G.termios_raw);
475 static void cookmode()
477 tcsetattr(0, TCSADRAIN, &G.termios_def);
480 extern int telnet_main(int argc, char** argv)
485 struct pollfd ufds[2];
492 memset(&G, 0, sizeof G);
494 if (tcgetattr(0, &G.termios_def) < 0)
497 G.termios_raw = G.termios_def;
499 cfmakeraw(&G.termios_raw);
501 if (argc < 2) show_usage();
502 port = (argc > 2)? getport(argv[2]): 23;
504 G.buf = xmalloc(DATABUFSIZE);
505 G.iacbuf = xmalloc(IACBUFSIZE);
507 host = getserver(argv[1]);
509 G.netfd = remote_connect(host, port);
511 signal(SIGINT, fgotsig);
514 ufds[0].fd = 0; ufds[1].fd = G.netfd;
515 ufds[0].events = ufds[1].events = POLLIN;
519 FD_SET(G.netfd, &readfds);
526 fd_set rfds = readfds;
528 switch (select(maxfd, &rfds, NULL, NULL, NULL))
530 switch (poll(ufds, 2, -1))
536 /* error, ignore and/or log something, bay go to loop */
545 if (ufds[0].revents) /* well, should check POLLIN, but ... */
547 if (FD_ISSET(0, &rfds))
550 G.len = read(0, G.buf, DATABUFSIZE);
555 TRACE(0, ("Read con: %d\n", G.len));
561 if (ufds[1].revents) /* well, should check POLLIN, but ... */
563 if (FD_ISSET(G.netfd, &rfds))
566 G.len = read(G.netfd, G.buf, DATABUFSIZE);
570 WriteCS(1, "Connection closed by foreign host.\r\n");
573 TRACE(0, ("Read netfd (%d): %d\n", G.netfd, G.len));
581 static int getport(char * p)
583 unsigned int port = atoi(p);
585 if ((unsigned)(port - 1 ) > 65534)
587 error_msg_and_die("%s: bad port number", p);
592 static struct in_addr getserver(char * host)
597 if ((he = gethostbyname(host)) == NULL)
599 error_msg_and_die("%s: Unknown host", host);
601 memcpy(&addr, he->h_addr, sizeof addr);
603 TRACE(1, ("addr: %s\n", inet_ntoa(addr)));
608 static int create_socket()
610 return socket(AF_INET, SOCK_STREAM, 0);
613 static void setup_sockaddr_in(struct sockaddr_in * addr, int port)
615 memset(addr, 0, sizeof addr);
616 addr->sin_family = AF_INET;
617 addr->sin_port = htons(port);
621 static int local_bind(int port)
623 struct sockaddr_in s_addr;
624 int s = create_socket();
626 setup_sockaddr_in(&s_addr, port);
628 setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &one, sizeof one);
630 if (bind(s, &s_addr, sizeof s_addr) < 0)
632 char * e = sys_errlist[errno];
633 syserrorexit("bind");
642 static int remote_connect(struct in_addr addr, int port)
644 struct sockaddr_in s_addr;
645 int s = create_socket();
647 setup_sockaddr_in(&s_addr, port);
648 s_addr.sin_addr = addr;
650 setsockopt(s, SOL_SOCKET, SO_KEEPALIVE, &one, sizeof one);
652 if (connect(s, (struct sockaddr *)&s_addr, sizeof s_addr) < 0)
654 perror_msg_and_die("Unable to connect to remote host");
661 c-file-style: "linux"