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);
137 static const char telnet_usage[] =
138 "telnet host [port]\n"
139 #ifndef BB_FEATURE_TRIVIAL_HELP
140 "\nTelnet is used to establish interactive communication with another\n"
141 "computer over a network using the TELNET protocol.\n"
146 static void doexit(int ev)
152 static void conescape()
156 if (G.gotsig) /* came from line mode... go raw */
159 WriteCS(1, "\r\nConsole escape. Commands are:\r\n\n"
160 " l go to line mode\r\n"
161 " c go to character mode\r\n"
162 " z suspend telnet\r\n"
163 " e exit telnet\r\n");
165 if (read(0, &b, 1) <= 0)
193 WriteCS(1, "continuing...\r\n");
202 static void handlenetoutput()
204 /* here we could do smart tricks how to handle 0xFF:s in output
205 * stream like writing twice every sequence of FF:s (thus doing
206 * many write()s. But I think interactive telnet application does
207 * not need to be 100% 8-bit clean, so changing every 0xff:s to
213 for (i = G.len; i > 0; i--, p++)
223 write(G.netfd, G.buf, G.len);
227 static void handlenetinput()
232 for (i = 0; i < G.len; i++)
236 if (G.telstate == 0) /* most of the time state == 0 */
255 if (c == IAC) /* IAC IAC -> 0xFF */
265 G.telstate = TS_SUB1;
275 G.telstate = TS_0; /* DATA MARK must be added later */
278 case TS_OPT: /* WILL, WONT, DO, DONT */
282 case TS_SUB1: /* Subnegotiation */
283 case TS_SUB2: /* Subnegotiation */
284 if (subneg(c) == TRUE)
291 if (G.iaclen) iacflush();
292 if (G.telstate == TS_0) G.telstate = 0;
298 write(1, G.buf, G.len);
302 /* ******************************* */
304 static inline void putiac(int c)
306 G.iacbuf[G.iaclen++] = c;
310 static void putiac2(byte wwdd, byte c)
312 if (G.iaclen + 3 > IACBUFSIZE)
321 static void putiac1(byte c)
323 if (G.iaclen + 2 > IACBUFSIZE)
331 /* void putiacstring (subneg strings) */
333 /* ******************************* */
335 char const escapecharis[] = "\r\nEscape character is ";
337 static void setConMode()
339 if (G.telflags & UF_ECHO)
341 if (G.charmode == CHM_TRY) {
343 fprintf(stdout, "\r\nEntering character mode%s'^]'.\r\n", escapecharis);
349 if (G.charmode != CHM_OFF) {
350 G.charmode = CHM_OFF;
351 fprintf(stdout, "\r\nEntering line mode%s'^C'.\r\n", escapecharis);
357 /* ******************************* */
359 static void will_charmode()
361 G.charmode = CHM_TRY;
362 G.telflags |= (UF_ECHO | UF_SGA);
365 putiac2(DO, TELOPT_ECHO);
366 putiac2(DO, TELOPT_SGA);
370 static void do_linemode()
372 G.charmode = CHM_TRY;
373 G.telflags &= ~(UF_ECHO | UF_SGA);
376 putiac2(DONT, TELOPT_ECHO);
377 putiac2(DONT, TELOPT_SGA);
381 /* ******************************* */
383 static inline void to_notsup(char c)
385 if (G.telwish == WILL) putiac2(DONT, c);
386 else if (G.telwish == DO) putiac2(WONT, c);
389 static inline void to_echo()
391 /* if server requests ECHO, don't agree */
392 if (G.telwish == DO) { putiac2(WONT, TELOPT_ECHO); return; }
393 else if (G.telwish == DONT) return;
395 if (G.telflags & UF_ECHO)
397 if (G.telwish == WILL)
401 if (G.telwish == WONT)
404 if (G.charmode != CHM_OFF)
405 G.telflags ^= UF_ECHO;
407 if (G.telflags & UF_ECHO)
408 putiac2(DO, TELOPT_ECHO);
410 putiac2(DONT, TELOPT_ECHO);
413 WriteCS(1, "\r\n"); /* sudden modec */
416 static inline void to_sga()
418 /* daemon always sends will/wont, client do/dont */
420 if (G.telflags & UF_SGA)
422 if (G.telwish == WILL)
426 if (G.telwish == WONT)
429 if ((G.telflags ^= UF_SGA) & UF_SGA) /* toggle */
430 putiac2(DO, TELOPT_SGA);
432 putiac2(DONT, TELOPT_SGA);
437 static void telopt(byte c)
441 case TELOPT_ECHO: to_echo(c); break;
442 case TELOPT_SGA: to_sga(c); break;
443 default: to_notsup(c); break;
448 /* ******************************* */
450 /* subnegotiation -- ignore all */
452 static int subneg(byte c)
458 G.telstate = TS_SUB2;
463 G.telstate = TS_SUB1;
469 /* ******************************* */
471 static void fgotsig(int sig)
477 static void rawmode()
479 tcsetattr(0, TCSADRAIN, &G.termios_raw);
482 static void cookmode()
484 tcsetattr(0, TCSADRAIN, &G.termios_def);
487 extern int telnet_main(int argc, char** argv)
492 struct pollfd ufds[2];
499 memset(&G, 0, sizeof G);
501 if (tcgetattr(0, &G.termios_def) < 0)
504 G.termios_raw = G.termios_def;
506 cfmakeraw(&G.termios_raw);
508 if (argc < 2) usage(telnet_usage);
509 port = (argc > 2)? getport(argv[2]): 23;
511 G.buf = xmalloc(DATABUFSIZE);
512 G.iacbuf = xmalloc(IACBUFSIZE);
514 host = getserver(argv[1]);
516 G.netfd = remote_connect(host, port);
518 signal(SIGINT, fgotsig);
521 ufds[0].fd = 0; ufds[1].fd = G.netfd;
522 ufds[0].events = ufds[1].events = POLLIN;
526 FD_SET(G.netfd, &readfds);
533 fd_set rfds = readfds;
535 switch (select(maxfd, &rfds, NULL, NULL, NULL))
537 switch (poll(ufds, 2, -1))
543 /* error, ignore and/or log something, bay go to loop */
552 if (ufds[0].revents) /* well, should check POLLIN, but ... */
554 if (FD_ISSET(0, &rfds))
557 G.len = read(0, G.buf, DATABUFSIZE);
562 TRACE(0, ("Read con: %d\n", G.len));
568 if (ufds[1].revents) /* well, should check POLLIN, but ... */
570 if (FD_ISSET(G.netfd, &rfds))
573 G.len = read(G.netfd, G.buf, DATABUFSIZE);
577 WriteCS(1, "Connection closed by foreign host.\r\n");
580 TRACE(0, ("Read netfd (%d): %d\n", G.netfd, G.len));
588 static int getport(char * p)
590 unsigned int port = atoi(p);
592 if ((unsigned)(port - 1 ) > 65534)
594 fatalError("%s: bad port number\n", p);
599 static struct in_addr getserver(char * host)
604 if ((he = gethostbyname(host)) == NULL)
606 fatalError("%s: Unkonwn host\n", host);
608 memcpy(&addr, he->h_addr, sizeof addr);
610 TRACE(1, ("addr: %s\n", inet_ntoa(addr)));
615 static int create_socket()
617 return socket(AF_INET, SOCK_STREAM, 0);
620 static void setup_sockaddr_in(struct sockaddr_in * addr, int port)
622 memset(addr, 0, sizeof addr);
623 addr->sin_family = AF_INET;
624 addr->sin_port = htons(port);
628 static int local_bind(int port)
630 struct sockaddr_in s_addr;
631 int s = create_socket();
633 setup_sockaddr_in(&s_addr, port);
635 setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &one, sizeof one);
637 if (bind(s, &s_addr, sizeof s_addr) < 0)
639 char * e = sys_errlist[errno];
640 syserrorexit("bind");
649 static int remote_connect(struct in_addr addr, int port)
651 struct sockaddr_in s_addr;
652 int s = create_socket();
654 setup_sockaddr_in(&s_addr, port);
655 s_addr.sin_addr = addr;
657 setsockopt(s, SOL_SOCKET, SO_KEEPALIVE, &one, sizeof one);
659 if (connect(s, (struct sockaddr *)&s_addr, sizeof s_addr) < 0)
661 fatalError("Unable to connect to remote host: %s\n", strerror(errno));
668 c-file-style: "linux"