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>
42 #include <arpa/telnet.h>
43 #include <sys/types.h>
44 #include <sys/socket.h>
45 #include <netinet/in.h>
53 #include <arpa/inet.h> /* for inet_ntoa()... */
54 #define TRACE(x, y) do { if (x) printf y; } while (0)
66 #define DATABUFSIZE 128
67 #define IACBUFSIZE 128
82 #define WriteCS(fd, str) write(fd, str, sizeof str -1)
84 typedef unsigned char byte;
86 /* use globals to reduce size ??? */ /* test this hypothesis later */
88 int netfd; /* console fd:s are 0 and 1 (and 2) */
89 /* same buffer used both for network and console read/write */
90 char * buf; /* allocating so static size is smaller */
92 byte telstate; /* telnet negotiation state from network input */
93 byte telwish; /* DO, DONT, WILL, WONT */
97 /* buffer to handle telnet negotiations */
99 short iaclen; /* could even use byte */
100 struct termios termios_def;
101 struct termios termios_raw;
104 #define xUSE_GLOBALVAR_PTR /* xUSE... -> don't use :D (makes smaller code) */
106 #ifdef USE_GLOBALVAR_PTR
107 struct Globalvars * Gptr;
113 static inline void iacflush()
115 write(G.netfd, G.iacbuf, G.iaclen);
119 /* Function prototypes */
120 static int getport(char * p);
121 static struct in_addr getserver(char * p);
122 static int create_socket();
123 static void setup_sockaddr_in(struct sockaddr_in * addr, int port);
124 static int remote_connect(struct in_addr addr, int port);
125 static void rawmode();
126 static void cookmode();
127 static void do_linemode();
128 static void will_charmode();
129 static void telopt(byte c);
130 static int subneg(byte c);
132 static int local_bind(int port);
138 static void doexit(int ev)
144 static void conescape()
148 if (G.gotsig) /* came from line mode... go raw */
151 WriteCS(1, "\r\nConsole escape. Commands are:\r\n\n"
152 " l go to line mode\r\n"
153 " c go to character mode\r\n"
154 " z suspend telnet\r\n"
155 " e exit telnet\r\n");
157 if (read(0, &b, 1) <= 0)
185 WriteCS(1, "continuing...\r\n");
194 static void handlenetoutput()
196 /* here we could do smart tricks how to handle 0xFF:s in output
197 * stream like writing twice every sequence of FF:s (thus doing
198 * many write()s. But I think interactive telnet application does
199 * not need to be 100% 8-bit clean, so changing every 0xff:s to
205 for (i = G.len; i > 0; i--, p++)
215 write(G.netfd, G.buf, G.len);
219 static void handlenetinput()
224 for (i = 0; i < G.len; i++)
228 if (G.telstate == 0) /* most of the time state == 0 */
247 if (c == IAC) /* IAC IAC -> 0xFF */
257 G.telstate = TS_SUB1;
267 G.telstate = TS_0; /* DATA MARK must be added later */
270 case TS_OPT: /* WILL, WONT, DO, DONT */
274 case TS_SUB1: /* Subnegotiation */
275 case TS_SUB2: /* Subnegotiation */
276 if (subneg(c) == TRUE)
283 if (G.iaclen) iacflush();
284 if (G.telstate == TS_0) G.telstate = 0;
290 write(1, G.buf, G.len);
294 /* ******************************* */
296 static inline void putiac(int c)
298 G.iacbuf[G.iaclen++] = c;
302 static void putiac2(byte wwdd, byte c)
304 if (G.iaclen + 3 > IACBUFSIZE)
313 static void putiac1(byte c)
315 if (G.iaclen + 2 > IACBUFSIZE)
323 /* void putiacstring (subneg strings) */
325 /* ******************************* */
327 char const escapecharis[] = "\r\nEscape character is ";
329 static void setConMode()
331 if (G.telflags & UF_ECHO)
333 if (G.charmode == CHM_TRY) {
335 fprintf(stdout, "\r\nEntering character mode%s'^]'.\r\n", escapecharis);
341 if (G.charmode != CHM_OFF) {
342 G.charmode = CHM_OFF;
343 fprintf(stdout, "\r\nEntering line mode%s'^C'.\r\n", escapecharis);
349 /* ******************************* */
351 static void will_charmode()
353 G.charmode = CHM_TRY;
354 G.telflags |= (UF_ECHO | UF_SGA);
357 putiac2(DO, TELOPT_ECHO);
358 putiac2(DO, TELOPT_SGA);
362 static void do_linemode()
364 G.charmode = CHM_TRY;
365 G.telflags &= ~(UF_ECHO | UF_SGA);
368 putiac2(DONT, TELOPT_ECHO);
369 putiac2(DONT, TELOPT_SGA);
373 /* ******************************* */
375 static inline void to_notsup(char c)
377 if (G.telwish == WILL) putiac2(DONT, c);
378 else if (G.telwish == DO) putiac2(WONT, c);
381 static inline void to_echo()
383 /* if server requests ECHO, don't agree */
384 if (G.telwish == DO) { putiac2(WONT, TELOPT_ECHO); return; }
385 else if (G.telwish == DONT) return;
387 if (G.telflags & UF_ECHO)
389 if (G.telwish == WILL)
393 if (G.telwish == WONT)
396 if (G.charmode != CHM_OFF)
397 G.telflags ^= UF_ECHO;
399 if (G.telflags & UF_ECHO)
400 putiac2(DO, TELOPT_ECHO);
402 putiac2(DONT, TELOPT_ECHO);
405 WriteCS(1, "\r\n"); /* sudden modec */
408 static inline void to_sga()
410 /* daemon always sends will/wont, client do/dont */
412 if (G.telflags & UF_SGA)
414 if (G.telwish == WILL)
418 if (G.telwish == WONT)
421 if ((G.telflags ^= UF_SGA) & UF_SGA) /* toggle */
422 putiac2(DO, TELOPT_SGA);
424 putiac2(DONT, TELOPT_SGA);
429 static void telopt(byte c)
433 case TELOPT_ECHO: to_echo(c); break;
434 case TELOPT_SGA: to_sga(c); break;
435 default: to_notsup(c); break;
440 /* ******************************* */
442 /* subnegotiation -- ignore all */
444 static int subneg(byte c)
450 G.telstate = TS_SUB2;
455 G.telstate = TS_SUB1;
461 /* ******************************* */
463 static void fgotsig(int sig)
469 static void rawmode()
471 tcsetattr(0, TCSADRAIN, &G.termios_raw);
474 static void cookmode()
476 tcsetattr(0, TCSADRAIN, &G.termios_def);
479 extern int telnet_main(int argc, char** argv)
484 struct pollfd ufds[2];
491 memset(&G, 0, sizeof G);
493 if (tcgetattr(0, &G.termios_def) < 0)
496 G.termios_raw = G.termios_def;
498 cfmakeraw(&G.termios_raw);
500 if (argc < 2) usage(telnet_usage);
501 port = (argc > 2)? getport(argv[2]): 23;
503 G.buf = xmalloc(DATABUFSIZE);
504 G.iacbuf = xmalloc(IACBUFSIZE);
506 host = getserver(argv[1]);
508 G.netfd = remote_connect(host, port);
510 signal(SIGINT, fgotsig);
513 ufds[0].fd = 0; ufds[1].fd = G.netfd;
514 ufds[0].events = ufds[1].events = POLLIN;
518 FD_SET(G.netfd, &readfds);
525 fd_set rfds = readfds;
527 switch (select(maxfd, &rfds, NULL, NULL, NULL))
529 switch (poll(ufds, 2, -1))
535 /* error, ignore and/or log something, bay go to loop */
544 if (ufds[0].revents) /* well, should check POLLIN, but ... */
546 if (FD_ISSET(0, &rfds))
549 G.len = read(0, G.buf, DATABUFSIZE);
554 TRACE(0, ("Read con: %d\n", G.len));
560 if (ufds[1].revents) /* well, should check POLLIN, but ... */
562 if (FD_ISSET(G.netfd, &rfds))
565 G.len = read(G.netfd, G.buf, DATABUFSIZE);
569 WriteCS(1, "Connection closed by foreign host.\r\n");
572 TRACE(0, ("Read netfd (%d): %d\n", G.netfd, G.len));
580 static int getport(char * p)
582 unsigned int port = atoi(p);
584 if ((unsigned)(port - 1 ) > 65534)
586 error_msg_and_die("%s: bad port number\n", p);
591 static struct in_addr getserver(char * host)
596 if ((he = gethostbyname(host)) == NULL)
598 error_msg_and_die("%s: Unknown host\n", host);
600 memcpy(&addr, he->h_addr, sizeof addr);
602 TRACE(1, ("addr: %s\n", inet_ntoa(addr)));
607 static int create_socket()
609 return socket(AF_INET, SOCK_STREAM, 0);
612 static void setup_sockaddr_in(struct sockaddr_in * addr, int port)
614 memset(addr, 0, sizeof addr);
615 addr->sin_family = AF_INET;
616 addr->sin_port = htons(port);
620 static int local_bind(int port)
622 struct sockaddr_in s_addr;
623 int s = create_socket();
625 setup_sockaddr_in(&s_addr, port);
627 setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &one, sizeof one);
629 if (bind(s, &s_addr, sizeof s_addr) < 0)
631 char * e = sys_errlist[errno];
632 syserrorexit("bind");
641 static int remote_connect(struct in_addr addr, int port)
643 struct sockaddr_in s_addr;
644 int s = create_socket();
646 setup_sockaddr_in(&s_addr, port);
647 s_addr.sin_addr = addr;
649 setsockopt(s, SOL_SOCKET, SO_KEEPALIVE, &one, sizeof one);
651 if (connect(s, (struct sockaddr *)&s_addr, sizeof s_addr) < 0)
653 error_msg_and_die("Unable to connect to remote host: %s\n", strerror(errno));
660 c-file-style: "linux"