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https://github.com/sheumann/hush.git
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667 lines
12 KiB
C
667 lines
12 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* telnet implementation for busybox
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*
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* Author: Tomi Ollila <too@iki.fi>
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* Copyright (C) 1994-2000 by Tomi Ollila
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*
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* Created: Thu Apr 7 13:29:41 1994 too
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* Last modified: Fri Jun 9 14:34:24 2000 too
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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* HISTORY
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* Revision 3.1 1994/04/17 11:31:54 too
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* initial revision
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* Modified 2000/06/13 for inclusion into BusyBox by Erik Andersen
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* <andersen@lineo.com>
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*
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*/
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#include <termios.h>
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#include <unistd.h>
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#include <errno.h>
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#include <stdlib.h>
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#include <stdarg.h>
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#include <string.h>
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#include <signal.h>
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#include <arpa/telnet.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <netdb.h>
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#include "busybox.h"
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#if 0
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static const int DOTRACE = 1;
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#endif
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#ifdef DOTRACE
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#include <arpa/inet.h> /* for inet_ntoa()... */
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#define TRACE(x, y) do { if (x) printf y; } while (0)
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#else
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#define TRACE(x, y)
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#endif
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#if 0
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#define USE_POLL
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#include <sys/poll.h>
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#else
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#include <sys/time.h>
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#endif
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static const int DATABUFSIZE = 128;
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static const int IACBUFSIZE = 128;
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static const int CHM_TRY = 0;
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static const int CHM_ON = 1;
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static const int CHM_OFF = 2;
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static const int UF_ECHO = 0x01;
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static const int UF_SGA = 0x02;
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enum {
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TS_0 = 1,
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TS_IAC = 2,
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TS_OPT = 3,
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TS_SUB1 = 4,
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TS_SUB2 = 5,
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};
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#define WriteCS(fd, str) write(fd, str, sizeof str -1)
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typedef unsigned char byte;
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/* use globals to reduce size ??? */ /* test this hypothesis later */
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static struct Globalvars {
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int netfd; /* console fd:s are 0 and 1 (and 2) */
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/* same buffer used both for network and console read/write */
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char * buf; /* allocating so static size is smaller */
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short len;
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byte telstate; /* telnet negotiation state from network input */
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byte telwish; /* DO, DONT, WILL, WONT */
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byte charmode;
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byte telflags;
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byte gotsig;
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/* buffer to handle telnet negotiations */
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char * iacbuf;
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short iaclen; /* could even use byte */
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struct termios termios_def;
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struct termios termios_raw;
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} G;
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#define xUSE_GLOBALVAR_PTR /* xUSE... -> don't use :D (makes smaller code) */
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#ifdef USE_GLOBALVAR_PTR
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struct Globalvars * Gptr;
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#define G (*Gptr)
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#else
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static struct Globalvars G;
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#endif
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static inline void iacflush()
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{
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write(G.netfd, G.iacbuf, G.iaclen);
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G.iaclen = 0;
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}
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/* Function prototypes */
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static int getport(char * p);
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static struct in_addr getserver(char * p);
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static int create_socket();
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static void setup_sockaddr_in(struct sockaddr_in * addr, int port);
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static int remote_connect(struct in_addr addr, int port);
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static void rawmode();
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static void cookmode();
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static void do_linemode();
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static void will_charmode();
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static void telopt(byte c);
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static int subneg(byte c);
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#if 0
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static int local_bind(int port);
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#endif
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/* Some globals */
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static int one = 1;
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static void doexit(int ev)
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{
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cookmode();
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exit(ev);
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}
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static void conescape()
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{
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char b;
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if (G.gotsig) /* came from line mode... go raw */
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rawmode();
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WriteCS(1, "\r\nConsole escape. Commands are:\r\n\n"
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" l go to line mode\r\n"
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" c go to character mode\r\n"
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" z suspend telnet\r\n"
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" e exit telnet\r\n");
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if (read(0, &b, 1) <= 0)
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doexit(1);
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switch (b)
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{
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case 'l':
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if (!G.gotsig)
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{
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do_linemode();
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goto rrturn;
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}
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break;
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case 'c':
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if (G.gotsig)
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{
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will_charmode();
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goto rrturn;
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}
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break;
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case 'z':
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cookmode();
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kill(0, SIGTSTP);
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rawmode();
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break;
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case 'e':
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doexit(0);
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}
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WriteCS(1, "continuing...\r\n");
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if (G.gotsig)
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cookmode();
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rrturn:
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G.gotsig = 0;
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}
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static void handlenetoutput()
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{
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/* here we could do smart tricks how to handle 0xFF:s in output
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* stream like writing twice every sequence of FF:s (thus doing
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* many write()s. But I think interactive telnet application does
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* not need to be 100% 8-bit clean, so changing every 0xff:s to
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* 0x7f:s */
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int i;
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byte * p = G.buf;
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for (i = G.len; i > 0; i--, p++)
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{
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if (*p == 0x1d)
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{
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conescape();
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return;
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}
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if (*p == 0xff)
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*p = 0x7f;
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}
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write(G.netfd, G.buf, G.len);
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}
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static void handlenetinput()
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{
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int i;
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int cstart = 0;
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for (i = 0; i < G.len; i++)
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{
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byte c = G.buf[i];
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if (G.telstate == 0) /* most of the time state == 0 */
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{
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if (c == IAC)
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{
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cstart = i;
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G.telstate = TS_IAC;
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}
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}
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else
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switch (G.telstate)
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{
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case TS_0:
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if (c == IAC)
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G.telstate = TS_IAC;
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else
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G.buf[cstart++] = c;
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break;
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case TS_IAC:
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if (c == IAC) /* IAC IAC -> 0xFF */
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{
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G.buf[cstart++] = c;
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G.telstate = TS_0;
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break;
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}
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/* else */
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switch (c)
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{
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case SB:
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G.telstate = TS_SUB1;
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break;
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case DO:
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case DONT:
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case WILL:
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case WONT:
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G.telwish = c;
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G.telstate = TS_OPT;
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break;
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default:
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G.telstate = TS_0; /* DATA MARK must be added later */
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}
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break;
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case TS_OPT: /* WILL, WONT, DO, DONT */
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telopt(c);
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G.telstate = TS_0;
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break;
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case TS_SUB1: /* Subnegotiation */
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case TS_SUB2: /* Subnegotiation */
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if (subneg(c) == TRUE)
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G.telstate = TS_0;
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break;
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}
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}
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if (G.telstate)
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{
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if (G.iaclen) iacflush();
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if (G.telstate == TS_0) G.telstate = 0;
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G.len = cstart;
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}
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if (G.len)
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write(1, G.buf, G.len);
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}
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/* ******************************* */
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static inline void putiac(int c)
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{
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G.iacbuf[G.iaclen++] = c;
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}
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static void putiac2(byte wwdd, byte c)
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{
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if (G.iaclen + 3 > IACBUFSIZE)
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iacflush();
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putiac(IAC);
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putiac(wwdd);
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putiac(c);
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}
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#if 0
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static void putiac1(byte c)
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{
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if (G.iaclen + 2 > IACBUFSIZE)
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iacflush();
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putiac(IAC);
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putiac(c);
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}
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#endif
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/* void putiacstring (subneg strings) */
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/* ******************************* */
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static char const escapecharis[] = "\r\nEscape character is ";
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static void setConMode()
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{
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if (G.telflags & UF_ECHO)
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{
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if (G.charmode == CHM_TRY) {
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G.charmode = CHM_ON;
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printf("\r\nEntering character mode%s'^]'.\r\n", escapecharis);
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rawmode();
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}
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}
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else
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{
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if (G.charmode != CHM_OFF) {
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G.charmode = CHM_OFF;
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printf("\r\nEntering line mode%s'^C'.\r\n", escapecharis);
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cookmode();
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}
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}
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}
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/* ******************************* */
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static void will_charmode()
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{
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G.charmode = CHM_TRY;
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G.telflags |= (UF_ECHO | UF_SGA);
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setConMode();
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putiac2(DO, TELOPT_ECHO);
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putiac2(DO, TELOPT_SGA);
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iacflush();
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}
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static void do_linemode()
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{
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G.charmode = CHM_TRY;
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G.telflags &= ~(UF_ECHO | UF_SGA);
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setConMode();
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putiac2(DONT, TELOPT_ECHO);
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putiac2(DONT, TELOPT_SGA);
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iacflush();
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}
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/* ******************************* */
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static inline void to_notsup(char c)
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{
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if (G.telwish == WILL) putiac2(DONT, c);
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else if (G.telwish == DO) putiac2(WONT, c);
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}
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static inline void to_echo()
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{
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/* if server requests ECHO, don't agree */
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if (G.telwish == DO) { putiac2(WONT, TELOPT_ECHO); return; }
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else if (G.telwish == DONT) return;
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if (G.telflags & UF_ECHO)
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{
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if (G.telwish == WILL)
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return;
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}
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else
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if (G.telwish == WONT)
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return;
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if (G.charmode != CHM_OFF)
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G.telflags ^= UF_ECHO;
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if (G.telflags & UF_ECHO)
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putiac2(DO, TELOPT_ECHO);
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else
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putiac2(DONT, TELOPT_ECHO);
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setConMode();
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WriteCS(1, "\r\n"); /* sudden modec */
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}
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static inline void to_sga()
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{
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/* daemon always sends will/wont, client do/dont */
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if (G.telflags & UF_SGA)
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{
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if (G.telwish == WILL)
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return;
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}
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else
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if (G.telwish == WONT)
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return;
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if ((G.telflags ^= UF_SGA) & UF_SGA) /* toggle */
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putiac2(DO, TELOPT_SGA);
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else
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putiac2(DONT, TELOPT_SGA);
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return;
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}
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static void telopt(byte c)
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{
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switch (c)
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{
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case TELOPT_ECHO: to_echo(c); break;
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case TELOPT_SGA: to_sga(c); break;
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default: to_notsup(c); break;
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}
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}
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/* ******************************* */
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/* subnegotiation -- ignore all */
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static int subneg(byte c)
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{
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switch (G.telstate)
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{
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case TS_SUB1:
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if (c == IAC)
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G.telstate = TS_SUB2;
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break;
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case TS_SUB2:
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if (c == SE)
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return TRUE;
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G.telstate = TS_SUB1;
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/* break; */
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}
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return FALSE;
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}
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/* ******************************* */
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static void fgotsig(int sig)
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{
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G.gotsig = sig;
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}
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static void rawmode()
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{
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tcsetattr(0, TCSADRAIN, &G.termios_raw);
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}
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static void cookmode()
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{
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tcsetattr(0, TCSADRAIN, &G.termios_def);
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}
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extern int telnet_main(int argc, char** argv)
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{
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struct in_addr host;
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int port;
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#ifdef USE_POLL
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struct pollfd ufds[2];
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#else
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fd_set readfds;
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int maxfd;
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#endif
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memset(&G, 0, sizeof G);
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if (tcgetattr(0, &G.termios_def) < 0)
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exit(1);
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G.termios_raw = G.termios_def;
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cfmakeraw(&G.termios_raw);
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if (argc < 2) show_usage();
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port = (argc > 2)? getport(argv[2]): 23;
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G.buf = xmalloc(DATABUFSIZE);
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G.iacbuf = xmalloc(IACBUFSIZE);
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host = getserver(argv[1]);
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G.netfd = remote_connect(host, port);
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signal(SIGINT, fgotsig);
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#ifdef USE_POLL
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ufds[0].fd = 0; ufds[1].fd = G.netfd;
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ufds[0].events = ufds[1].events = POLLIN;
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#else
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FD_ZERO(&readfds);
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FD_SET(0, &readfds);
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FD_SET(G.netfd, &readfds);
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maxfd = G.netfd + 1;
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#endif
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while (1)
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{
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#ifndef USE_POLL
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fd_set rfds = readfds;
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switch (select(maxfd, &rfds, NULL, NULL, NULL))
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#else
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switch (poll(ufds, 2, -1))
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#endif
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{
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case 0:
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/* timeout */
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case -1:
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/* error, ignore and/or log something, bay go to loop */
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if (G.gotsig)
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conescape();
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else
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sleep(1);
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break;
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default:
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#ifdef USE_POLL
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if (ufds[0].revents) /* well, should check POLLIN, but ... */
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#else
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if (FD_ISSET(0, &rfds))
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#endif
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{
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G.len = read(0, G.buf, DATABUFSIZE);
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if (G.len <= 0)
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doexit(0);
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TRACE(0, ("Read con: %d\n", G.len));
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handlenetoutput();
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}
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#ifdef USE_POLL
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if (ufds[1].revents) /* well, should check POLLIN, but ... */
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#else
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if (FD_ISSET(G.netfd, &rfds))
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#endif
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{
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G.len = read(G.netfd, G.buf, DATABUFSIZE);
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if (G.len <= 0)
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{
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WriteCS(1, "Connection closed by foreign host.\r\n");
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doexit(1);
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}
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TRACE(0, ("Read netfd (%d): %d\n", G.netfd, G.len));
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handlenetinput();
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}
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}
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}
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}
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static int getport(char * p)
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{
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unsigned int port = atoi(p);
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if ((unsigned)(port - 1 ) > 65534)
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{
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error_msg_and_die("%s: bad port number", p);
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}
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return port;
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}
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static struct in_addr getserver(char * host)
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{
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|
struct in_addr addr;
|
|
|
|
struct hostent * he;
|
|
if ((he = gethostbyname(host)) == NULL)
|
|
{
|
|
error_msg_and_die("%s: Unknown host", host);
|
|
}
|
|
memcpy(&addr, he->h_addr, sizeof addr);
|
|
|
|
TRACE(1, ("addr: %s\n", inet_ntoa(addr)));
|
|
|
|
return addr;
|
|
}
|
|
|
|
static int create_socket()
|
|
{
|
|
return socket(AF_INET, SOCK_STREAM, 0);
|
|
}
|
|
|
|
static void setup_sockaddr_in(struct sockaddr_in * addr, int port)
|
|
{
|
|
memset(addr, 0, sizeof(struct sockaddr_in));
|
|
addr->sin_family = AF_INET;
|
|
addr->sin_port = htons(port);
|
|
}
|
|
|
|
#if 0
|
|
static int local_bind(int port)
|
|
{
|
|
struct sockaddr_in s_addr;
|
|
int s = create_socket();
|
|
|
|
setup_sockaddr_in(&s_addr, port);
|
|
|
|
setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &one, sizeof one);
|
|
|
|
if (bind(s, &s_addr, sizeof s_addr) < 0)
|
|
{
|
|
char * e = sys_errlist[errno];
|
|
syserrorexit("bind");
|
|
exit(1);
|
|
}
|
|
listen(s, 1);
|
|
|
|
return s;
|
|
}
|
|
#endif
|
|
|
|
static int remote_connect(struct in_addr addr, int port)
|
|
{
|
|
struct sockaddr_in s_addr;
|
|
int s = create_socket();
|
|
|
|
setup_sockaddr_in(&s_addr, port);
|
|
s_addr.sin_addr = addr;
|
|
|
|
setsockopt(s, SOL_SOCKET, SO_KEEPALIVE, &one, sizeof one);
|
|
|
|
if (connect(s, (struct sockaddr *)&s_addr, sizeof s_addr) < 0)
|
|
{
|
|
perror_msg_and_die("Unable to connect to remote host");
|
|
}
|
|
return s;
|
|
}
|
|
|
|
/*
|
|
Local Variables:
|
|
c-file-style: "linux"
|
|
c-basic-offset: 4
|
|
tab-width: 4
|
|
End:
|
|
*/
|
|
|