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https://github.com/sheumann/hush.git
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651 lines
12 KiB
C
651 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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* 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 <arpa/telnet.h>
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#include <netinet/in.h>
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#include "libbb.h"
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#ifdef DOTRACE
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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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enum {
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DATABUFSIZE = 128,
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IACBUFSIZE = 128,
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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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typedef unsigned char byte;
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enum { netfd = 3 };
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struct globals {
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int iaclen; /* could even use byte, but it's a loss on x86 */
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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 do_termios;
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#if ENABLE_FEATURE_TELNET_TTYPE
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char *ttype;
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#endif
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#if ENABLE_FEATURE_TELNET_AUTOLOGIN
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const char *autologin;
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#endif
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#if ENABLE_FEATURE_AUTOWIDTH
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unsigned win_width, win_height;
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#endif
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/* same buffer used both for network and console read/write */
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char buf[DATABUFSIZE];
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/* buffer to handle telnet negotiations */
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char iacbuf[IACBUFSIZE];
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struct termios termios_def;
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struct termios termios_raw;
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};
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#define G (*(struct globals*)&bb_common_bufsiz1)
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void BUG_telnet_globals_too_big(void);
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#define INIT_G() do { \
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if (sizeof(G) > COMMON_BUFSIZE) \
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BUG_telnet_globals_too_big(); \
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/* memset(&G, 0, sizeof G); - already is */ \
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} while (0)
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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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static void iac_flush(void)
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{
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write(netfd, G.iacbuf, G.iaclen);
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G.iaclen = 0;
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}
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#define write_str(fd, str) write(fd, str, sizeof(str) - 1)
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static void doexit(int ev) NORETURN;
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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 con_escape(void)
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{
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char b;
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if (bb_got_signal) /* came from line mode... go raw */
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rawmode();
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write_str(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(STDIN_FILENO, &b, 1) <= 0)
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doexit(EXIT_FAILURE);
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switch (b) {
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case 'l':
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if (!bb_got_signal) {
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do_linemode();
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goto ret;
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}
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break;
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case 'c':
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if (bb_got_signal) {
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will_charmode();
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goto ret;
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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(EXIT_SUCCESS);
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}
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write_str(1, "continuing...\r\n");
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if (bb_got_signal)
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cookmode();
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ret:
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bb_got_signal = 0;
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}
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static void handle_net_output(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 - why do 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 really useful for me. I hope that
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* other people will find it interesting too.
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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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if (*p == 0x1d) {
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con_escape();
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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(netfd, outbuf, j);
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}
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static void handle_net_input(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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byte c = G.buf[i];
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if (G.telstate == 0) { /* most of the time state == 0 */
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if (c == IAC) {
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cstart = i;
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G.telstate = TS_IAC;
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}
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continue;
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}
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switch (G.telstate) {
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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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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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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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if (G.iaclen)
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iac_flush();
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if (G.telstate == TS_0)
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G.telstate = 0;
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len = cstart;
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}
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if (len)
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write(STDOUT_FILENO, G.buf, len);
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}
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static void put_iac(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 put_iac2(byte wwdd, byte c)
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{
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if (G.iaclen + 3 > IACBUFSIZE)
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iac_flush();
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put_iac(IAC);
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put_iac(wwdd);
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put_iac(c);
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}
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#if ENABLE_FEATURE_TELNET_TTYPE
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static void put_iac_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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iac_flush();
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put_iac(IAC);
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put_iac(SB);
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put_iac(c);
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put_iac(0);
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while (*str)
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put_iac(*str++);
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put_iac(IAC);
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put_iac(SE);
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}
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#endif
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#if ENABLE_FEATURE_TELNET_AUTOLOGIN
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static void put_iac_subopt_autologin(void)
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{
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int len = strlen(G.autologin) + 6; // (2 + 1 + 1 + strlen + 2)
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const char *user = "USER";
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if (G.iaclen + len > IACBUFSIZE)
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iac_flush();
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put_iac(IAC);
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put_iac(SB);
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put_iac(TELOPT_NEW_ENVIRON);
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put_iac(TELQUAL_IS);
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put_iac(NEW_ENV_VAR);
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while (*user)
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put_iac(*user++);
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put_iac(NEW_ENV_VALUE);
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while (*G.autologin)
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put_iac(*G.autologin++);
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put_iac(IAC);
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put_iac(SE);
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}
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#endif
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#if ENABLE_FEATURE_AUTOWIDTH
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static void put_iac_naws(byte c, int x, int y)
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{
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if (G.iaclen + 9 > IACBUFSIZE)
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iac_flush();
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put_iac(IAC);
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put_iac(SB);
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put_iac(c);
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put_iac((x >> 8) & 0xff);
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put_iac(x & 0xff);
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put_iac((y >> 8) & 0xff);
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put_iac(y & 0xff);
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put_iac(IAC);
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put_iac(SE);
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}
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#endif
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static char const escapecharis[] ALIGN1 = "\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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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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} else {
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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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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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put_iac2(DO, TELOPT_ECHO);
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put_iac2(DO, TELOPT_SGA);
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iac_flush();
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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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put_iac2(DONT, TELOPT_ECHO);
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put_iac2(DONT, TELOPT_SGA);
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iac_flush();
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}
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static void to_notsup(char c)
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{
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if (G.telwish == WILL)
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put_iac2(DONT, c);
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else if (G.telwish == DO)
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put_iac2(WONT, c);
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}
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static 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) {
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put_iac2(WONT, TELOPT_ECHO);
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return;
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}
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if (G.telwish == DONT)
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return;
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if (G.telflags & UF_ECHO) {
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if (G.telwish == WILL)
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return;
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} else 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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put_iac2(DO, TELOPT_ECHO);
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else
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put_iac2(DONT, TELOPT_ECHO);
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setConMode();
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write_str(1, "\r\n"); /* sudden modec */
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}
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static 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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if (G.telwish == WILL)
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return;
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} else if (G.telwish == WONT)
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return;
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G.telflags ^= UF_SGA; /* toggle */
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if (G.telflags & UF_SGA)
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put_iac2(DO, TELOPT_SGA);
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else
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put_iac2(DONT, TELOPT_SGA);
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}
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#if ENABLE_FEATURE_TELNET_TTYPE
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static 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 (G.ttype)
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put_iac2(WILL, TELOPT_TTYPE);
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else
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put_iac2(WONT, TELOPT_TTYPE);
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}
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#endif
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#if ENABLE_FEATURE_TELNET_AUTOLOGIN
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static 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 (G.autologin)
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put_iac2(WILL, TELOPT_NEW_ENVIRON);
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else
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put_iac2(WONT, TELOPT_NEW_ENVIRON);
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}
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#endif
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#if ENABLE_FEATURE_AUTOWIDTH
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static void to_naws(void)
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{
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/* Tell server we will do NAWS */
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put_iac2(WILL, TELOPT_NAWS);
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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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case TELOPT_ECHO:
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to_echo(); break;
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case TELOPT_SGA:
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to_sga(); break;
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#if ENABLE_FEATURE_TELNET_TTYPE
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case TELOPT_TTYPE:
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to_ttype(); break;
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#endif
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#if ENABLE_FEATURE_TELNET_AUTOLOGIN
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case TELOPT_NEW_ENVIRON:
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to_new_environ(); break;
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#endif
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#if ENABLE_FEATURE_AUTOWIDTH
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case TELOPT_NAWS:
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to_naws();
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put_iac_naws(c, G.win_width, G.win_height);
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break;
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#endif
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default:
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to_notsup(c);
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break;
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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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case TS_SUB1:
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if (c == IAC)
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G.telstate = TS_SUB2;
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#if ENABLE_FEATURE_TELNET_TTYPE
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else
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if (c == TELOPT_TTYPE)
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put_iac_subopt(TELOPT_TTYPE, G.ttype);
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#endif
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#if ENABLE_FEATURE_TELNET_AUTOLOGIN
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else
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if (c == TELOPT_NEW_ENVIRON)
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put_iac_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;
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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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static void rawmode(void)
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{
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if (G.do_termios)
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tcsetattr(0, TCSADRAIN, &G.termios_raw);
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}
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static void cookmode(void)
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{
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if (G.do_termios)
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tcsetattr(0, TCSADRAIN, &G.termios_def);
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}
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/* poll gives smaller (-70 bytes) code */
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#define USE_POLL 1
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int telnet_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int telnet_main(int argc UNUSED_PARAM, char **argv)
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{
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char *host;
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int port;
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int len;
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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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INIT_G();
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#if ENABLE_FEATURE_AUTOWIDTH
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get_terminal_width_height(0, &G.win_width, &G.win_height);
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#endif
|
|
|
|
#if ENABLE_FEATURE_TELNET_TTYPE
|
|
G.ttype = getenv("TERM");
|
|
#endif
|
|
|
|
if (tcgetattr(0, &G.termios_def) >= 0) {
|
|
G.do_termios = 1;
|
|
G.termios_raw = G.termios_def;
|
|
cfmakeraw(&G.termios_raw);
|
|
}
|
|
|
|
#if ENABLE_FEATURE_TELNET_AUTOLOGIN
|
|
if (1 & getopt32(argv, "al:", &G.autologin))
|
|
G.autologin = getenv("USER");
|
|
argv += optind;
|
|
#else
|
|
argv++;
|
|
#endif
|
|
if (!*argv)
|
|
bb_show_usage();
|
|
host = *argv++;
|
|
port = bb_lookup_port(*argv ? *argv++ : "telnet", "tcp", 23);
|
|
if (*argv) /* extra params?? */
|
|
bb_show_usage();
|
|
|
|
xmove_fd(create_and_connect_stream_or_die(host, port), netfd);
|
|
|
|
setsockopt(netfd, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1));
|
|
|
|
signal(SIGINT, record_signo);
|
|
|
|
#ifdef USE_POLL
|
|
ufds[0].fd = 0; ufds[1].fd = netfd;
|
|
ufds[0].events = ufds[1].events = POLLIN;
|
|
#else
|
|
FD_ZERO(&readfds);
|
|
FD_SET(STDIN_FILENO, &readfds);
|
|
FD_SET(netfd, &readfds);
|
|
maxfd = 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 (bb_got_signal)
|
|
con_escape();
|
|
else
|
|
sleep(1);
|
|
break;
|
|
default:
|
|
|
|
#ifdef USE_POLL
|
|
if (ufds[0].revents) /* well, should check POLLIN, but ... */
|
|
#else
|
|
if (FD_ISSET(STDIN_FILENO, &rfds))
|
|
#endif
|
|
{
|
|
len = read(STDIN_FILENO, G.buf, DATABUFSIZE);
|
|
if (len <= 0)
|
|
doexit(EXIT_SUCCESS);
|
|
TRACE(0, ("Read con: %d\n", len));
|
|
handle_net_output(len);
|
|
}
|
|
|
|
#ifdef USE_POLL
|
|
if (ufds[1].revents) /* well, should check POLLIN, but ... */
|
|
#else
|
|
if (FD_ISSET(netfd, &rfds))
|
|
#endif
|
|
{
|
|
len = read(netfd, G.buf, DATABUFSIZE);
|
|
if (len <= 0) {
|
|
write_str(1, "Connection closed by foreign host\r\n");
|
|
doexit(EXIT_FAILURE);
|
|
}
|
|
TRACE(0, ("Read netfd (%d): %d\n", netfd, len));
|
|
handle_net_input(len);
|
|
}
|
|
}
|
|
} /* while (1) */
|
|
}
|