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730 lines
13 KiB
C
730 lines
13 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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* Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
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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 <andersen@codepoet.org>
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* Modified 2001/05/07 to add ability to pass TTYPE to remote host by Jim McQuillan
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* <jam@ltsp.org>
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* Modified 2004/02/11 to add ability to pass the USER variable to remote host
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* by Fernando Silveira <swrh@gmx.net>
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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 "busybox.h"
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#if 0
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enum { 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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#define DATABUFSIZE 128
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#define IACBUFSIZE 128
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enum {
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CHM_TRY = 0,
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CHM_ON = 1,
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CHM_OFF = 2,
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UF_ECHO = 0x01,
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UF_SGA = 0x02,
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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[DATABUFSIZE]; /* allocating so static size is smaller */
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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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byte do_termios;
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/* buffer to handle telnet negotiations */
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char iacbuf[IACBUFSIZE];
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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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#endif
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static inline void iacflush(void)
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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 void rawmode(void);
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static void cookmode(void);
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static void do_linemode(void);
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static void will_charmode(void);
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static void telopt(byte c);
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static int subneg(byte c);
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/* Some globals */
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static int one = 1;
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#ifdef CONFIG_FEATURE_TELNET_TTYPE
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static char *ttype;
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#endif
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#ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
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static const char *autologin;
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#endif
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#ifdef CONFIG_FEATURE_AUTOWIDTH
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static int win_width, win_height;
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#endif
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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(void)
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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(int len)
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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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*
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* 2002-mar-21, Przemyslaw Czerpak (druzus@polbox.com)
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* I don't agree.
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* first - I cannot use programs like sz/rz
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* second - the 0x0D is sent as one character and if the next
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* char is 0x0A then it's eaten by a server side.
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* third - whay doy you have to make 'many write()s'?
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* I don't understand.
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* So I implemented it. It's realy useful for me. I hope that
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* others people will find it interesting to.
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*/
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int i, j;
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byte * p = (byte*)G.buf;
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byte outbuf[4*DATABUFSIZE];
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for (i = len, j = 0; 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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outbuf[j++] = *p;
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if (*p == 0xff)
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outbuf[j++] = 0xff;
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else if (*p == 0x0d)
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outbuf[j++] = 0x00;
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}
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if (j > 0 )
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write(G.netfd, outbuf, j);
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}
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static void handlenetinput(int len)
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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 < 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))
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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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len = cstart;
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}
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if (len)
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write(1, G.buf, 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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#ifdef CONFIG_FEATURE_TELNET_TTYPE
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static void putiac_subopt(byte c, char *str)
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{
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int len = strlen(str) + 6; // ( 2 + 1 + 1 + strlen + 2 )
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if (G.iaclen + len > IACBUFSIZE)
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iacflush();
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putiac(IAC);
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putiac(SB);
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putiac(c);
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putiac(0);
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while(*str)
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putiac(*str++);
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putiac(IAC);
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putiac(SE);
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}
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#endif
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#ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
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static void putiac_subopt_autologin(void)
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{
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int len = strlen(autologin) + 6; // (2 + 1 + 1 + strlen + 2)
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char *user = "USER";
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if (G.iaclen + len > IACBUFSIZE)
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iacflush();
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putiac(IAC);
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putiac(SB);
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putiac(TELOPT_NEW_ENVIRON);
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putiac(TELQUAL_IS);
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putiac(NEW_ENV_VAR);
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while(*user)
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putiac(*user++);
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putiac(NEW_ENV_VALUE);
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while(*autologin)
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putiac(*autologin++);
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putiac(IAC);
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putiac(SE);
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}
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#endif
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#ifdef CONFIG_FEATURE_AUTOWIDTH
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static void putiac_naws(byte c, int x, int y)
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{
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if (G.iaclen + 9 > IACBUFSIZE)
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iacflush();
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putiac(IAC);
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putiac(SB);
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putiac(c);
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putiac((x >> 8) & 0xff);
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putiac(x & 0xff);
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putiac((y >> 8) & 0xff);
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putiac(y & 0xff);
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putiac(IAC);
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putiac(SE);
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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(void)
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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(void)
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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(void)
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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(void)
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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(void)
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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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#ifdef CONFIG_FEATURE_TELNET_TTYPE
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static inline void to_ttype(void)
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{
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/* Tell server we will (or won't) do TTYPE */
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if(ttype)
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putiac2(WILL, TELOPT_TTYPE);
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else
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putiac2(WONT, TELOPT_TTYPE);
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return;
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}
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#endif
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#ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
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static inline void to_new_environ(void)
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{
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/* Tell server we will (or will not) do AUTOLOGIN */
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if (autologin)
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putiac2(WILL, TELOPT_NEW_ENVIRON);
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else
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putiac2(WONT, TELOPT_NEW_ENVIRON);
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return;
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}
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#endif
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#ifdef CONFIG_FEATURE_AUTOWIDTH
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static inline void to_naws(void)
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{
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/* Tell server we will do NAWS */
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putiac2(WILL, TELOPT_NAWS);
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return;
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}
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#endif
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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(); break;
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case TELOPT_SGA: to_sga(); break;
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#ifdef CONFIG_FEATURE_TELNET_TTYPE
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case TELOPT_TTYPE: to_ttype();break;
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#endif
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#ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
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case TELOPT_NEW_ENVIRON: to_new_environ(); break;
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#endif
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#ifdef CONFIG_FEATURE_AUTOWIDTH
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case TELOPT_NAWS: to_naws();
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putiac_naws(c, win_width, win_height);
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break;
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#endif
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default: to_notsup(c);
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break;
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}
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}
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/* ******************************* */
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/* subnegotiation -- ignore all (except TTYPE,NAWS) */
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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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#ifdef CONFIG_FEATURE_TELNET_TTYPE
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else
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if (c == TELOPT_TTYPE)
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putiac_subopt(TELOPT_TTYPE,ttype);
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#endif
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#ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
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else
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if (c == TELOPT_NEW_ENVIRON)
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putiac_subopt_autologin();
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#endif
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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;
|
|
G.telstate = TS_SUB1;
|
|
/* break; */
|
|
}
|
|
return FALSE;
|
|
}
|
|
|
|
/* ******************************* */
|
|
|
|
static void fgotsig(int sig)
|
|
{
|
|
G.gotsig = sig;
|
|
}
|
|
|
|
|
|
static void rawmode(void)
|
|
{
|
|
if (G.do_termios) tcsetattr(0, TCSADRAIN, &G.termios_raw);
|
|
}
|
|
|
|
static void cookmode(void)
|
|
{
|
|
if (G.do_termios) tcsetattr(0, TCSADRAIN, &G.termios_def);
|
|
}
|
|
|
|
int telnet_main(int argc, char** argv)
|
|
{
|
|
int len;
|
|
struct sockaddr_in s_in;
|
|
#ifdef USE_POLL
|
|
struct pollfd ufds[2];
|
|
#else
|
|
fd_set readfds;
|
|
int maxfd;
|
|
#endif
|
|
|
|
#ifdef CONFIG_FEATURE_AUTOWIDTH
|
|
get_terminal_width_height(0, &win_width, &win_height);
|
|
#endif
|
|
|
|
#ifdef CONFIG_FEATURE_TELNET_TTYPE
|
|
ttype = getenv("TERM");
|
|
#endif
|
|
|
|
memset(&G, 0, sizeof G);
|
|
|
|
if (tcgetattr(0, &G.termios_def) >= 0) {
|
|
G.do_termios = 1;
|
|
|
|
G.termios_raw = G.termios_def;
|
|
cfmakeraw(&G.termios_raw);
|
|
}
|
|
|
|
if (argc < 2)
|
|
bb_show_usage();
|
|
|
|
#ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
|
|
if (1 & bb_getopt_ulflags(argc, argv, "al:", &autologin))
|
|
autologin = getenv("USER");
|
|
|
|
if (optind < argc) {
|
|
bb_lookup_host(&s_in, argv[optind++]);
|
|
s_in.sin_port = bb_lookup_port((optind < argc) ? argv[optind++] :
|
|
"telnet", "tcp", 23);
|
|
if (optind < argc)
|
|
bb_show_usage();
|
|
} else
|
|
bb_show_usage();
|
|
#else
|
|
bb_lookup_host(&s_in, argv[1]);
|
|
s_in.sin_port = bb_lookup_port((argc == 3) ? argv[2] : "telnet", "tcp", 23);
|
|
#endif
|
|
|
|
G.netfd = xconnect(&s_in);
|
|
|
|
setsockopt(G.netfd, SOL_SOCKET, SO_KEEPALIVE, &one, sizeof one);
|
|
|
|
signal(SIGINT, fgotsig);
|
|
|
|
#ifdef USE_POLL
|
|
ufds[0].fd = 0; ufds[1].fd = G.netfd;
|
|
ufds[0].events = ufds[1].events = POLLIN;
|
|
#else
|
|
FD_ZERO(&readfds);
|
|
FD_SET(0, &readfds);
|
|
FD_SET(G.netfd, &readfds);
|
|
maxfd = G.netfd + 1;
|
|
#endif
|
|
|
|
while (1)
|
|
{
|
|
#ifndef USE_POLL
|
|
fd_set rfds = readfds;
|
|
|
|
switch (select(maxfd, &rfds, NULL, NULL, NULL))
|
|
#else
|
|
switch (poll(ufds, 2, -1))
|
|
#endif
|
|
{
|
|
case 0:
|
|
/* timeout */
|
|
case -1:
|
|
/* error, ignore and/or log something, bay go to loop */
|
|
if (G.gotsig)
|
|
conescape();
|
|
else
|
|
sleep(1);
|
|
break;
|
|
default:
|
|
|
|
#ifdef USE_POLL
|
|
if (ufds[0].revents) /* well, should check POLLIN, but ... */
|
|
#else
|
|
if (FD_ISSET(0, &rfds))
|
|
#endif
|
|
{
|
|
len = read(0, G.buf, DATABUFSIZE);
|
|
|
|
if (len <= 0)
|
|
doexit(0);
|
|
|
|
TRACE(0, ("Read con: %d\n", len));
|
|
|
|
handlenetoutput(len);
|
|
}
|
|
|
|
#ifdef USE_POLL
|
|
if (ufds[1].revents) /* well, should check POLLIN, but ... */
|
|
#else
|
|
if (FD_ISSET(G.netfd, &rfds))
|
|
#endif
|
|
{
|
|
len = read(G.netfd, G.buf, DATABUFSIZE);
|
|
|
|
if (len <= 0)
|
|
{
|
|
WriteCS(1, "Connection closed by foreign host.\r\n");
|
|
doexit(1);
|
|
}
|
|
TRACE(0, ("Read netfd (%d): %d\n", G.netfd, len));
|
|
|
|
handlenetinput(len);
|
|
}
|
|
}
|
|
}
|
|
}
|