busybox/telnet.c

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/*
* $Id: telnet.c,v 1.2 2000/05/01 19:10:52 erik Exp $
* Mini telnet implementation for busybox
*
* Copyright (C) 2000 by Randolph Chung <tausq@debian.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* This version of telnet is adapted (but very heavily modified) from the
* telnet in netkit-telnet 0.16, which is:
*
* Copyright (c) 1989 The Regents of the University of California.
* All rights reserved.
*
* Original copyright notice is retained at the end of this file.
*/
#include "internal.h"
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <ctype.h>
#include <signal.h>
#include <errno.h>
#include <netdb.h>
#include <termios.h>
#include <netinet/in.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#define TELOPTS
#include <arpa/telnet.h>
#include <arpa/inet.h>
static int STDIN = 0;
static int STDOUT = 1;
static const char *telnet_usage = "telnet host [port]\n\n";
static struct termios saved_tc;
static unsigned char options[NTELOPTS];
static char tr_state = 0; /* telnet send and receive state */
static unsigned char subbuffer[256];
static unsigned char *subpointer, *subend;
#define SB_CLEAR() subpointer = subbuffer;
#define SB_TERM() { subend = subpointer; SB_CLEAR(); }
#define SB_ACCUM(c) if (subpointer < (subbuffer+sizeof subbuffer)) { *subpointer++ = (c); }
#define SB_GET() (*subpointer++)
#define SB_PEEK() (*subpointer)
#define SB_EOF() (subpointer >= subend)
#define SB_LEN() (subend - subpointer)
#define TELNETPORT 23
#define MASK_WILL 0x01
#define MASK_WONT 0x04
#define MASK_DO 0x10
#define MASK_DONT 0x40
#define TFLAG_ISSET(opt, flag) (options[opt] & MASK_##flag)
#define TFLAG_SET(opt, flag) (options[opt] |= MASK_##flag)
#define TFLAG_CLR(opt, flag) (options[opt] &= ~MASK_##flag)
#define PERROR(ctx) do { fprintf(stderr, "%s: %s\n", ctx, strerror(errno)); \
return; } while (0)
#define TS_DATA 0
#define TS_IAC 1
#define TS_WILL 2
#define TS_WONT 3
#define TS_DO 4
#define TS_DONT 5
#define TS_CR 6
#define TS_SB 7 /* sub-option collection */
#define TS_SE 8 /* looking for sub-option end */
/* prototypes */
static void telnet_init(void);
static void telnet_start(char *host, int port);
static void telnet_shutdown(void);
/* ******************************************************************* */
#define SENDCOMMAND(c,o) \
char buf[3]; \
buf[0] = IAC; buf[1] = c; buf[2] = o; \
write(s, buf, sizeof(buf));
static inline void telnet_sendwill(int s, int c) { SENDCOMMAND(WILL, c); }
static inline void telnet_sendwont(int s, int c) { SENDCOMMAND(WONT, c); }
static inline void telnet_senddo(int s, int c) { SENDCOMMAND(DO, c); }
static inline void telnet_senddont(int s, int c) { SENDCOMMAND(DONT, c); }
static void telnet_setoptions(int s)
{
/*
telnet_sendwill(s, TELOPT_NAWS); TFLAG_SET(TELOPT_NAWS, WILL);
telnet_sendwill(s, TELOPT_TSPEED); TFLAG_SET(TELOPT_TSPEED, WILL);
telnet_sendwill(s, TELOPT_NEW_ENVIRON); TFLAG_SET(TELOPT_NEW_ENVIRON, WILL);
telnet_senddo(s, TELOPT_STATUS); TFLAG_SET(TELOPT_STATUS, DO);
telnet_sendwill(s, TELOPT_TTYPE); TFLAG_SET(TELOPT_TTYPE, WILL);
*/
telnet_senddo(s, TELOPT_SGA); TFLAG_SET(TELOPT_SGA, DO);
telnet_sendwill(s, TELOPT_LFLOW); TFLAG_SET(TELOPT_LFLOW, WILL);
telnet_sendwill(s, TELOPT_LINEMODE); TFLAG_SET(TELOPT_LINEMODE, WILL);
telnet_senddo(s, TELOPT_BINARY); TFLAG_SET(TELOPT_BINARY, DO);
telnet_sendwill(s, TELOPT_BINARY); TFLAG_SET(TELOPT_BINARY, WILL);
}
static void telnet_suboptions(int net)
{
char buf[256];
switch (SB_GET()) {
case TELOPT_TTYPE:
if (TFLAG_ISSET(TELOPT_TTYPE, WONT)) return;
if (SB_EOF() || SB_GET() != TELQUAL_SEND) {
return;
} else {
const char *name = getenv("TERM");
if (name) {
snprintf(buf, sizeof(buf), "%c%c%c%c%s%c%c", IAC, SB,
TELOPT_TTYPE, TELQUAL_IS, name, IAC, SE);
write(net, buf, strlen(name)+6);
}
}
break;
case TELOPT_TSPEED:
if (TFLAG_ISSET(TELOPT_TSPEED, WONT)) return;
if (SB_EOF()) return;
if (SB_GET() == TELQUAL_SEND) {
/*
long oospeed, iispeed;
netoring.printf("%c%c%c%c%ld,%ld%c%c", IAC, SB, TELOPT_TSPEED,
TELQUAL_IS, oospeed, iispeed, IAC, SE);
*/
}
break;
/*
case TELOPT_LFLOW:
if (TFLAG_ISSET(TELOPT_LFLOW, WONT)) return;
if (SB_EOF()) return;
switch(SB_GET()) {
case 1: localflow = 1; break;
case 0: localflow = 0; break;
default: return;
}
break;
case TELOPT_LINEMODE:
if (TFLAG_ISSET(TELOPT_LINEMODE, WONT)) return;
if (SB_EOF()) return;
switch (SB_GET()) {
case WILL: lm_will(subpointer, SB_LEN()); break;
case WONT: lm_wont(subpointer, SB_LEN()); break;
case DO: lm_do(subpointer, SB_LEN()); break;
case DONT: lm_dont(subpointer, SB_LEN()); break;
case LM_SLC: slc(subpointer, SB_LEN()); break;
case LM_MODE: lm_mode(subpointer, SB_LEN(), 0); break;
default: break;
}
break;
case TELOPT_ENVIRON:
if (SB_EOF()) return;
switch(SB_PEEK()) {
case TELQUAL_IS:
case TELQUAL_INFO:
if (TFLAG_ISSET(TELOPT_ENVIRON, DONT)) return;
break;
case TELQUAL_SEND:
if (TFLAG_ISSET(TELOPT_ENVIRON, WONT)) return;
break;
default:
return;
}
env_opt(subpointer, SB_LEN());
break;
*/
case TELOPT_XDISPLOC:
if (TFLAG_ISSET(TELOPT_XDISPLOC, WONT)) return;
if (SB_EOF()) return;
if (SB_GET() == TELQUAL_SEND) {
const char *dp = getenv("DISPLAY");
if (dp) {
snprintf(buf, sizeof(buf), "%c%c%c%c%s%c%c", IAC, SB,
TELOPT_XDISPLOC, TELQUAL_IS, dp, IAC, SE);
write(net, buf, strlen(dp)+6);
}
}
break;
default:
break;
}
}
static void sighandler(int sig)
{
telnet_shutdown();
exit(0);
}
static int telnet_send(int tty, int net)
{
int ret;
unsigned char ch;
while ((ret = read(tty, &ch, 1)) > 0) {
if (ch == 29) { /* 29 -- ctrl-] */
/* do something here? */
exit(0);
} else {
ret = write(net, &ch, 1);
break;
}
}
if (ret == -1 && errno == EWOULDBLOCK) return 1;
return ret;
}
static int telnet_recv(int net, int tty)
{
/* globals: tr_state - telnet receive state */
int ret, c = 0;
unsigned char ch;
while ((ret = read(net, &ch, 1)) > 0) {
c = ch;
/* printf("%02X ", c); fflush(stdout); */
switch (tr_state) {
case TS_DATA:
if (c == IAC) {
tr_state = TS_IAC;
break;
} else {
write(tty, &c, 1);
}
break;
case TS_IAC:
switch (c) {
case WILL:
tr_state = TS_WILL; break;
case WONT:
tr_state = TS_WONT; break;
case DO:
tr_state = TS_DO; break;
case DONT:
tr_state = TS_DONT; break;
case SB:
SB_CLEAR();
tr_state = TS_SB; break;
case IAC:
write(tty, &c, 1); /* fallthrough */
default:
tr_state = TS_DATA;
}
/* subnegotiation -- ignored for now */
case TS_SB:
if (c == IAC) tr_state = TS_SE;
else SB_ACCUM(c);
break;
case TS_SE:
if (c == IAC) {
SB_ACCUM(IAC);
tr_state = TS_SB;
} else if (c == SE) {
SB_ACCUM(IAC);
SB_ACCUM(SE);
subpointer -= 2;
SB_TERM();
telnet_suboptions(net);
tr_state = TS_DATA;
}
/* otherwise this is an error, but we ignore it for now */
break;
/* handle incoming requests */
case TS_WILL:
printf("WILL %s\n", telopts[c]);
if (!TFLAG_ISSET(c, DO)) {
if (c == TELOPT_BINARY) {
TFLAG_SET(c, DO);
TFLAG_CLR(c, DONT);
telnet_senddo(net, c);
} else {
TFLAG_SET(c, DONT);
telnet_senddont(net, c);
}
}
telnet_senddont(net, c);
tr_state = TS_DATA;
break;
case TS_WONT:
printf("WONT %s\n", telopts[c]);
if (!TFLAG_ISSET(c, DONT)) {
TFLAG_SET(c, DONT);
TFLAG_CLR(c, DO);
telnet_senddont(net, c);
}
tr_state = TS_DATA;
break;
case TS_DO:
printf("DO %s\n", telopts[c]);
if (!TFLAG_ISSET(c, WILL)) {
if (c == TELOPT_BINARY) {
TFLAG_SET(c, WILL);
TFLAG_CLR(c, WONT);
telnet_sendwill(net, c);
} else {
TFLAG_SET(c, WONT);
telnet_sendwont(net, c);
}
}
tr_state = TS_DATA;
break;
case TS_DONT:
printf("DONT %s\n", telopts[c]);
if (!TFLAG_ISSET(c, WONT)) {
TFLAG_SET(c, WONT);
TFLAG_CLR(c, WILL);
telnet_sendwont(net, c);
}
tr_state = TS_DATA;
break;
}
}
if (ret == -1 && errno == EWOULDBLOCK) return 1;
return ret;
}
/* ******************************************************************* */
static void telnet_init(void)
{
struct termios tmp_tc;
cc_t esc = (']' & 0x1f); /* ctrl-] */
memset(options, 0, sizeof(options));
SB_CLEAR();
tcgetattr(STDIN, &saved_tc);
tmp_tc = saved_tc;
tmp_tc.c_lflag &= ~ECHO; /* echo */
tmp_tc.c_oflag |= ONLCR; /* NL->CRLF translation */
tmp_tc.c_iflag |= ICRNL;
tmp_tc.c_iflag &= ~(IXANY|IXOFF|IXON); /* no flow control */
tmp_tc.c_lflag |= ISIG; /* trap signals */
tmp_tc.c_lflag &= ~ICANON; /* edit mode */
/* misc settings, compat with default telnet stuff */
tmp_tc.c_oflag &= ~TABDLY;
/* 8-bit clean */
tmp_tc.c_iflag &= ~ISTRIP;
tmp_tc.c_cflag &= ~(CSIZE|PARENB);
tmp_tc.c_cflag |= saved_tc.c_cflag & (CSIZE|PARENB);
tmp_tc.c_oflag |= OPOST;
/* set escape character */
tmp_tc.c_cc[VEOL] = esc;
tcsetattr(STDIN, TCSADRAIN, &tmp_tc);
}
static void telnet_start(char *hostname, int port)
{
struct hostent *host = 0;
struct sockaddr_in addr;
int s, c;
fd_set rfds, wfds;
memset(&addr, 0, sizeof(addr));
host = gethostbyname(hostname);
if (!host) {
fprintf(stderr, "Unknown host: %s\n", hostname);
return;
}
addr.sin_family = host->h_addrtype;
memcpy(&addr.sin_addr, host->h_addr, sizeof(addr.sin_addr));
addr.sin_port = htons(port);
printf("Trying %s...\n", inet_ntoa(addr.sin_addr));
if ((s = socket(AF_INET, SOCK_STREAM, 0)) < 0) PERROR("socket");
if (connect(s, (struct sockaddr *)&addr, sizeof(addr)) < 0)
PERROR("connect");
printf("Connected to %s\n", hostname);
printf("Escape character is ^]\n");
signal(SIGINT, sighandler);
signal(SIGQUIT, sighandler);
signal(SIGPIPE, sighandler);
signal(SIGWINCH, sighandler);
/* make inputs nonblocking */
c = 1;
ioctl(s, FIONBIO, &c);
ioctl(STDIN, FIONBIO, &c);
if (port == TELNETPORT) telnet_setoptions(s);
/* shuttle data back and forth between tty and socket */
while (1) {
FD_ZERO(&rfds);
FD_ZERO(&wfds);
FD_SET(s, &rfds);
/* FD_SET(s, &wfds); */
FD_SET(STDIN, &rfds);
/* FD_SET(STDOUT, &wfds); */
if ((c = select(s+1, &rfds, &wfds, 0, 0))) {
if (c == -1) {
/* handle errors */
PERROR("select");
}
if (FD_ISSET(s, &rfds)) {
/* input from network */
FD_CLR(s, &rfds);
c = telnet_recv(s, STDOUT);
if (c == 0) break;
if (c < 0) PERROR("telnet_recv");
}
if (FD_ISSET(STDIN, &rfds)) {
/* input from tty */
FD_CLR(STDIN, &rfds);
c = telnet_send(STDIN, s);
if (c == 0) break;
if (c < 0) PERROR("telnet_send");
}
}
}
return;
}
static void telnet_shutdown(void)
{
printf("\n");
tcsetattr(STDIN, TCSANOW, &saved_tc);
}
#ifdef STANDALONE_TELNET
void usage(const char *msg)
{
printf("%s", msg);
exit(0);
}
int main(int argc, char **argv)
#else
int telnet_main(int argc, char **argv)
#endif
{
int port = TELNETPORT;
argc--; argv++;
if (argc < 1) usage(telnet_usage);
if (argc > 1) port = atoi(argv[1]);
telnet_init();
atexit(telnet_shutdown);
telnet_start(argv[0], port);
return 0;
}
/*
* Copyright (c) 1988, 1990 Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/