busybox/networking/telnet.c

/* vi: set sw=4 ts=4: */
/*
 * telnet implementation for busybox
 *
 * Author: Tomi Ollila <too@iki.fi>
 * Copyright (C) 1994-2000 by Tomi Ollila
 *
 * Created: Thu Apr  7 13:29:41 1994 too
 * Last modified: Fri Jun  9 14:34:24 2000 too
 *
 * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
 *
 * HISTORY
 * Revision 3.1  1994/04/17  11:31:54  too
 * initial revision
 * Modified 2000/06/13 for inclusion into BusyBox by Erik Andersen <andersen@codepoet.org>
 * Modified 2001/05/07 to add ability to pass TTYPE to remote host by Jim McQuillan
 * <jam@ltsp.org>
 * Modified 2004/02/11 to add ability to pass the USER variable to remote host
 * by Fernando Silveira <swrh@gmx.net>
 *
 */

#include <termios.h>
#include <arpa/telnet.h>
#include <netinet/in.h>
#include "busybox.h"

#ifdef DOTRACE
#include <arpa/inet.h> /* for inet_ntoa()... */
#define TRACE(x, y) do { if (x) printf y; } while (0)
#else
#define TRACE(x, y)
#endif

#define DATABUFSIZE  128
#define IACBUFSIZE   128

enum {
	CHM_TRY = 0,
	CHM_ON = 1,
	CHM_OFF = 2,

	UF_ECHO = 0x01,
	UF_SGA = 0x02,

	TS_0 = 1,
	TS_IAC = 2,
	TS_OPT = 3,
	TS_SUB1 = 4,
	TS_SUB2 = 5,
};

#define WriteCS(fd, str) write(fd, str, sizeof str -1)

typedef unsigned char byte;

/* use globals to reduce size ??? */ /* test this hypothesis later */
static struct Globalvars {
	int		netfd; /* console fd:s are 0 and 1 (and 2) */
    /* same buffer used both for network and console read/write */
	char    buf[DATABUFSIZE]; /* allocating so static size is smaller */
	byte	telstate; /* telnet negotiation state from network input */
	byte	telwish;  /* DO, DONT, WILL, WONT */
	byte    charmode;
	byte    telflags;
	byte	gotsig;
	byte	do_termios;
	/* buffer to handle telnet negotiations */
	char    iacbuf[IACBUFSIZE];
	short	iaclen; /* could even use byte */
	struct termios termios_def;
	struct termios termios_raw;
} G;

#define xUSE_GLOBALVAR_PTR /* xUSE... -> don't use :D (makes smaller code) */

#ifdef USE_GLOBALVAR_PTR
struct Globalvars * Gptr;
#define G (*Gptr)
#endif

static void iacflush(void)
{
	write(G.netfd, G.iacbuf, G.iaclen);
	G.iaclen = 0;
}

/* Function prototypes */
static void rawmode(void);
static void cookmode(void);
static void do_linemode(void);
static void will_charmode(void);
static void telopt(byte c);
static int subneg(byte c);

/* Some globals */
static const int one = 1;

#ifdef CONFIG_FEATURE_TELNET_TTYPE
static char *ttype;
#endif

#ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
static const char *autologin;
#endif

#ifdef CONFIG_FEATURE_AUTOWIDTH
static int win_width, win_height;
#endif

static void doexit(int ev)
{
	cookmode();
	exit(ev);
}

static void conescape(void)
{
	char b;

	if (G.gotsig)	/* came from line  mode... go raw */
		rawmode();

	WriteCS(1, "\r\nConsole escape. Commands are:\r\n\n"
			" l	go to line mode\r\n"
			" c	go to character mode\r\n"
			" z	suspend telnet\r\n"
			" e	exit telnet\r\n");

	if (read(0, &b, 1) <= 0)
		doexit(1);

	switch (b)
	{
	case 'l':
		if (!G.gotsig)
		{
			do_linemode();
			goto rrturn;
		}
		break;
	case 'c':
		if (G.gotsig)
		{
			will_charmode();
			goto rrturn;
		}
		break;
	case 'z':
		cookmode();
		kill(0, SIGTSTP);
		rawmode();
		break;
	case 'e':
		doexit(0);
	}

	WriteCS(1, "continuing...\r\n");

	if (G.gotsig)
		cookmode();

 rrturn:
	G.gotsig = 0;

}
static void handlenetoutput(int len)
{
	/*	here we could do smart tricks how to handle 0xFF:s in output
	 *	stream  like writing twice every sequence of FF:s (thus doing
	 *	many write()s. But I think interactive telnet application does
	 *	not need to be 100% 8-bit clean, so changing every 0xff:s to
	 *	0x7f:s
	 *
	 *	2002-mar-21, Przemyslaw Czerpak (druzus@polbox.com)
	 *	I don't agree.
	 *	first - I cannot use programs like sz/rz
	 *	second - the 0x0D is sent as one character and if the next
	 *		 char is 0x0A then it's eaten by a server side.
	 *	third - whay doy you have to make 'many write()s'?
	 *		I don't understand.
	 *	So I implemented it. It's realy useful for me. I hope that
	 *	others people will find it interesting to.
	 */

	int i, j;
	byte * p = (byte*)G.buf;
	byte outbuf[4*DATABUFSIZE];

	for (i = len, j = 0; i > 0; i--, p++)
	{
		if (*p == 0x1d)
		{
			conescape();
			return;
		}
		outbuf[j++] = *p;
		if (*p == 0xff)
			outbuf[j++] = 0xff;
		else if (*p == 0x0d)
			outbuf[j++] = 0x00;
	}
	if (j > 0 )
		write(G.netfd, outbuf, j);
}


static void handlenetinput(int len)
{
	int i;
	int cstart = 0;

	for (i = 0; i < len; i++)
	{
		byte c = G.buf[i];

		if (G.telstate == 0) /* most of the time state == 0 */
		{
			if (c == IAC)
			{
				cstart = i;
				G.telstate = TS_IAC;
			}
		}
		else
			switch (G.telstate)
			 {
			 case TS_0:
				 if (c == IAC)
					 G.telstate = TS_IAC;
				 else
					 G.buf[cstart++] = c;
				 break;

			 case TS_IAC:
				 if (c == IAC) /* IAC IAC -> 0xFF */
				 {
					 G.buf[cstart++] = c;
					 G.telstate = TS_0;
					 break;
				 }
				 /* else */
				 switch (c)
				 {
				 case SB:
					 G.telstate = TS_SUB1;
					 break;
				 case DO:
				 case DONT:
				 case WILL:
				 case WONT:
					 G.telwish =  c;
					 G.telstate = TS_OPT;
					 break;
				 default:
					 G.telstate = TS_0;	/* DATA MARK must be added later */
				 }
				 break;
			 case TS_OPT: /* WILL, WONT, DO, DONT */
				 telopt(c);
				 G.telstate = TS_0;
				 break;
			 case TS_SUB1: /* Subnegotiation */
			 case TS_SUB2: /* Subnegotiation */
				 if (subneg(c))
					 G.telstate = TS_0;
				 break;
			 }
	}
	if (G.telstate)
	{
		if (G.iaclen)			iacflush();
		if (G.telstate == TS_0)	G.telstate = 0;

		len = cstart;
	}

	if (len)
		write(1, G.buf, len);
}


/* ******************************* */

static void putiac(int c)
{
	G.iacbuf[G.iaclen++] = c;
}


static void putiac2(byte wwdd, byte c)
{
	if (G.iaclen + 3 > IACBUFSIZE)
		iacflush();

	putiac(IAC);
	putiac(wwdd);
	putiac(c);
}

#ifdef CONFIG_FEATURE_TELNET_TTYPE
static void putiac_subopt(byte c, char *str)
{
	int	len = strlen(str) + 6;   // ( 2 + 1 + 1 + strlen + 2 )

	if (G.iaclen + len > IACBUFSIZE)
		iacflush();

	putiac(IAC);
	putiac(SB);
	putiac(c);
	putiac(0);

	while (*str)
		putiac(*str++);

	putiac(IAC);
	putiac(SE);
}
#endif

#ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
static void putiac_subopt_autologin(void)
{
	int len = strlen(autologin) + 6;	// (2 + 1 + 1 + strlen + 2)
	char *user = "USER";

	if (G.iaclen + len > IACBUFSIZE)
		iacflush();

	putiac(IAC);
	putiac(SB);
	putiac(TELOPT_NEW_ENVIRON);
	putiac(TELQUAL_IS);
	putiac(NEW_ENV_VAR);

	while (*user)
		putiac(*user++);

	putiac(NEW_ENV_VALUE);

	while (*autologin)
		putiac(*autologin++);

	putiac(IAC);
	putiac(SE);
}
#endif

#ifdef CONFIG_FEATURE_AUTOWIDTH
static void putiac_naws(byte c, int x, int y)
{
	if (G.iaclen + 9 > IACBUFSIZE)
		iacflush();

	putiac(IAC);
	putiac(SB);
	putiac(c);

	putiac((x >> 8) & 0xff);
	putiac(x & 0xff);
	putiac((y >> 8) & 0xff);
	putiac(y & 0xff);

	putiac(IAC);
	putiac(SE);
}
#endif

/* void putiacstring (subneg strings) */

/* ******************************* */

static char const escapecharis[] = "\r\nEscape character is ";

static void setConMode(void)
{
	if (G.telflags & UF_ECHO)
	{
		if (G.charmode == CHM_TRY) {
			G.charmode = CHM_ON;
			printf("\r\nEntering character mode%s'^]'.\r\n", escapecharis);
			rawmode();
		}
	}
	else
	{
		if (G.charmode != CHM_OFF) {
			G.charmode = CHM_OFF;
			printf("\r\nEntering line mode%s'^C'.\r\n", escapecharis);
			cookmode();
		}
	}
}

/* ******************************* */

static void will_charmode(void)
{
	G.charmode = CHM_TRY;
	G.telflags |= (UF_ECHO | UF_SGA);
	setConMode();

	putiac2(DO, TELOPT_ECHO);
	putiac2(DO, TELOPT_SGA);
	iacflush();
}

static void do_linemode(void)
{
	G.charmode = CHM_TRY;
	G.telflags &= ~(UF_ECHO | UF_SGA);
	setConMode();

	putiac2(DONT, TELOPT_ECHO);
	putiac2(DONT, TELOPT_SGA);
	iacflush();
}

/* ******************************* */

static void to_notsup(char c)
{
	if      (G.telwish == WILL)	putiac2(DONT, c);
	else if (G.telwish == DO)	putiac2(WONT, c);
}

static void to_echo(void)
{
	/* if server requests ECHO, don't agree */
	if      (G.telwish == DO) {	putiac2(WONT, TELOPT_ECHO);	return; }
	else if (G.telwish == DONT)	return;

	if (G.telflags & UF_ECHO)
	{
		if (G.telwish == WILL)
			return;
	}
	else
		if (G.telwish == WONT)
			return;

	if (G.charmode != CHM_OFF)
		G.telflags ^= UF_ECHO;

	if (G.telflags & UF_ECHO)
		putiac2(DO, TELOPT_ECHO);
	else
		putiac2(DONT, TELOPT_ECHO);

	setConMode();
	WriteCS(1, "\r\n");  /* sudden modec */
}

static void to_sga(void)
{
	/* daemon always sends will/wont, client do/dont */

	if (G.telflags & UF_SGA)
	{
		if (G.telwish == WILL)
			return;
	}
	else
		if (G.telwish == WONT)
			return;

	if ((G.telflags ^= UF_SGA) & UF_SGA) /* toggle */
		putiac2(DO, TELOPT_SGA);
	else
		putiac2(DONT, TELOPT_SGA);

	return;
}

#ifdef CONFIG_FEATURE_TELNET_TTYPE
static void to_ttype(void)
{
	/* Tell server we will (or won't) do TTYPE */

	if(ttype)
		putiac2(WILL, TELOPT_TTYPE);
	else
		putiac2(WONT, TELOPT_TTYPE);

	return;
}
#endif

#ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
static void to_new_environ(void)
{
	/* Tell server we will (or will not) do AUTOLOGIN */

	if (autologin)
		putiac2(WILL, TELOPT_NEW_ENVIRON);
	else
		putiac2(WONT, TELOPT_NEW_ENVIRON);

	return;
}
#endif

#ifdef CONFIG_FEATURE_AUTOWIDTH
static void to_naws(void)
{
	/* Tell server we will do NAWS */
	putiac2(WILL, TELOPT_NAWS);
	return;
}
#endif

static void telopt(byte c)
{
	switch (c)
	{
		case TELOPT_ECHO:		to_echo();	break;
		case TELOPT_SGA:		to_sga();	break;
#ifdef CONFIG_FEATURE_TELNET_TTYPE
		case TELOPT_TTYPE:		to_ttype();break;
#endif
#ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
		case TELOPT_NEW_ENVIRON:	to_new_environ();	break;
#endif
#ifdef CONFIG_FEATURE_AUTOWIDTH
		case TELOPT_NAWS:		to_naws();
								putiac_naws(c, win_width, win_height);
								break;
#endif
		default:				to_notsup(c);
								break;
	}
}


/* ******************************* */

/* subnegotiation -- ignore all (except TTYPE,NAWS) */

static int subneg(byte c)
{
	switch (G.telstate)
	{
	case TS_SUB1:
		if (c == IAC)
			G.telstate = TS_SUB2;
#ifdef CONFIG_FEATURE_TELNET_TTYPE
		else
		if (c == TELOPT_TTYPE)
			putiac_subopt(TELOPT_TTYPE,ttype);
#endif
#ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
		else
		if (c == TELOPT_NEW_ENVIRON)
			putiac_subopt_autologin();
#endif
		break;
	case TS_SUB2:
		if (c == SE)
			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)
{
	char *host;
	int port;
	int len;
#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); - already is */

	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 & getopt32(argc, argv, "al:", &autologin))
		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();

	G.netfd = create_and_connect_stream_or_die(host, port);

	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);
			}
		}
	}
}
1	niro	532	/* vi: set sw=4 ts=4: */
2			/*
3			* telnet implementation for busybox
4			*
5			* Author: Tomi Ollila <too@iki.fi>
6			* Copyright (C) 1994-2000 by Tomi Ollila
7			*
8			* Created: Thu Apr 7 13:29:41 1994 too
9			* Last modified: Fri Jun 9 14:34:24 2000 too
10			*
11			* Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
12			*
13			* HISTORY
14			* Revision 3.1 1994/04/17 11:31:54 too
15			* initial revision
16			* Modified 2000/06/13 for inclusion into BusyBox by Erik Andersen <andersen@codepoet.org>
17			* Modified 2001/05/07 to add ability to pass TTYPE to remote host by Jim McQuillan
18			* <jam@ltsp.org>
19			* Modified 2004/02/11 to add ability to pass the USER variable to remote host
20			* by Fernando Silveira <swrh@gmx.net>
21			*
22			*/
23
24			#include <termios.h>
25			#include <arpa/telnet.h>
26			#include <netinet/in.h>
27			#include "busybox.h"
28
29			#ifdef DOTRACE
30			#include <arpa/inet.h> /* for inet_ntoa()... */
31			#define TRACE(x, y) do { if (x) printf y; } while (0)
32			#else
33			#define TRACE(x, y)
34			#endif
35
36			#define DATABUFSIZE 128
37			#define IACBUFSIZE 128
38
39			enum {
40			CHM_TRY = 0,
41			CHM_ON = 1,
42			CHM_OFF = 2,
43
44			UF_ECHO = 0x01,
45			UF_SGA = 0x02,
46
47			TS_0 = 1,
48			TS_IAC = 2,
49			TS_OPT = 3,
50			TS_SUB1 = 4,
51			TS_SUB2 = 5,
52			};
53
54			#define WriteCS(fd, str) write(fd, str, sizeof str -1)
55
56			typedef unsigned char byte;
57
58			/* use globals to reduce size ??? / / test this hypothesis later */
59			static struct Globalvars {
60			int netfd; /* console fd:s are 0 and 1 (and 2) */
61			/* same buffer used both for network and console read/write */
62			char buf[DATABUFSIZE]; /* allocating so static size is smaller */
63			byte telstate; /* telnet negotiation state from network input */
64			byte telwish; /* DO, DONT, WILL, WONT */
65			byte charmode;
66			byte telflags;
67			byte gotsig;
68			byte do_termios;
69			/* buffer to handle telnet negotiations */
70			char iacbuf[IACBUFSIZE];
71			short iaclen; /* could even use byte */
72			struct termios termios_def;
73			struct termios termios_raw;
74			} G;
75
76			#define xUSE_GLOBALVAR_PTR /* xUSE... -> don't use :D (makes smaller code) */
77
78			#ifdef USE_GLOBALVAR_PTR
79			struct Globalvars * Gptr;
80			#define G (*Gptr)
81			#endif
82
83			static void iacflush(void)
84			{
85			write(G.netfd, G.iacbuf, G.iaclen);
86			G.iaclen = 0;
87			}
88
89			/* Function prototypes */
90			static void rawmode(void);
91			static void cookmode(void);
92			static void do_linemode(void);
93			static void will_charmode(void);
94			static void telopt(byte c);
95			static int subneg(byte c);
96
97			/* Some globals */
98			static const int one = 1;
99
100			#ifdef CONFIG_FEATURE_TELNET_TTYPE
101			static char *ttype;
102			#endif
103
104			#ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
105			static const char *autologin;
106			#endif
107
108			#ifdef CONFIG_FEATURE_AUTOWIDTH
109			static int win_width, win_height;
110			#endif
111
112			static void doexit(int ev)
113			{
114			cookmode();
115			exit(ev);
116			}
117
118			static void conescape(void)
119			{
120			char b;
121
122			if (G.gotsig) /* came from line mode... go raw */
123			rawmode();
124
125			WriteCS(1, "\r\nConsole escape. Commands are:\r\n\n"
126			" l go to line mode\r\n"
127			" c go to character mode\r\n"
128			" z suspend telnet\r\n"
129			" e exit telnet\r\n");
130
131			if (read(0, &b, 1) <= 0)
132			doexit(1);
133
134			switch (b)
135			{
136			case 'l':
137			if (!G.gotsig)
138			{
139			do_linemode();
140			goto rrturn;
141			}
142			break;
143			case 'c':
144			if (G.gotsig)
145			{
146			will_charmode();
147			goto rrturn;
148			}
149			break;
150			case 'z':
151			cookmode();
152			kill(0, SIGTSTP);
153			rawmode();
154			break;
155			case 'e':
156			doexit(0);
157			}
158
159			WriteCS(1, "continuing...\r\n");
160
161			if (G.gotsig)
162			cookmode();
163
164			rrturn:
165			G.gotsig = 0;
166
167			}
168			static void handlenetoutput(int len)
169			{
170			/* here we could do smart tricks how to handle 0xFF:s in output
171			* stream like writing twice every sequence of FF:s (thus doing
172			* many write()s. But I think interactive telnet application does
173			* not need to be 100% 8-bit clean, so changing every 0xff:s to
174			* 0x7f:s
175			*
176			* 2002-mar-21, Przemyslaw Czerpak (druzus@polbox.com)
177			* I don't agree.
178			* first - I cannot use programs like sz/rz
179			* second - the 0x0D is sent as one character and if the next
180			* char is 0x0A then it's eaten by a server side.
181			* third - whay doy you have to make 'many write()s'?
182			* I don't understand.
183			* So I implemented it. It's realy useful for me. I hope that
184			* others people will find it interesting to.
185			*/
186
187			int i, j;
188			byte * p = (byte*)G.buf;
189			byte outbuf[4*DATABUFSIZE];
190
191			for (i = len, j = 0; i > 0; i--, p++)
192			{
193			if (*p == 0x1d)
194			{
195			conescape();
196			return;
197			}
198			outbuf[j++] = *p;
199			if (*p == 0xff)
200			outbuf[j++] = 0xff;
201			else if (*p == 0x0d)
202			outbuf[j++] = 0x00;
203			}
204			if (j > 0 )
205			write(G.netfd, outbuf, j);
206			}
207
208
209			static void handlenetinput(int len)
210			{
211			int i;
212			int cstart = 0;
213
214			for (i = 0; i < len; i++)
215			{
216			byte c = G.buf[i];
217
218			if (G.telstate == 0) /* most of the time state == 0 */
219			{
220			if (c == IAC)
221			{
222			cstart = i;
223			G.telstate = TS_IAC;
224			}
225			}
226			else
227			switch (G.telstate)
228			{
229			case TS_0:
230			if (c == IAC)
231			G.telstate = TS_IAC;
232			else
233			G.buf[cstart++] = c;
234			break;
235
236			case TS_IAC:
237			if (c == IAC) /* IAC IAC -> 0xFF */
238			{
239			G.buf[cstart++] = c;
240			G.telstate = TS_0;
241			break;
242			}
243			/* else */
244			switch (c)
245			{
246			case SB:
247			G.telstate = TS_SUB1;
248			break;
249			case DO:
250			case DONT:
251			case WILL:
252			case WONT:
253			G.telwish = c;
254			G.telstate = TS_OPT;
255			break;
256			default:
257			G.telstate = TS_0; /* DATA MARK must be added later */
258			}
259			break;
260			case TS_OPT: /* WILL, WONT, DO, DONT */
261			telopt(c);
262			G.telstate = TS_0;
263			break;
264			case TS_SUB1: /* Subnegotiation */
265			case TS_SUB2: /* Subnegotiation */
266			if (subneg(c))
267			G.telstate = TS_0;
268			break;
269			}
270			}
271			if (G.telstate)
272			{
273			if (G.iaclen) iacflush();
274			if (G.telstate == TS_0) G.telstate = 0;
275
276			len = cstart;
277			}
278
279			if (len)
280			write(1, G.buf, len);
281			}
282
283
284			/* ******************************* */
285
286			static void putiac(int c)
287			{
288			G.iacbuf[G.iaclen++] = c;
289			}
290
291
292			static void putiac2(byte wwdd, byte c)
293			{
294			if (G.iaclen + 3 > IACBUFSIZE)
295			iacflush();
296
297			putiac(IAC);
298			putiac(wwdd);
299			putiac(c);
300			}
301
302			#ifdef CONFIG_FEATURE_TELNET_TTYPE
303			static void putiac_subopt(byte c, char *str)
304			{
305			int len = strlen(str) + 6; // ( 2 + 1 + 1 + strlen + 2 )
306
307			if (G.iaclen + len > IACBUFSIZE)
308			iacflush();
309
310			putiac(IAC);
311			putiac(SB);
312			putiac(c);
313			putiac(0);
314
315			while (*str)
316			putiac(*str++);
317
318			putiac(IAC);
319			putiac(SE);
320			}
321			#endif
322
323			#ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
324			static void putiac_subopt_autologin(void)
325			{
326			int len = strlen(autologin) + 6; // (2 + 1 + 1 + strlen + 2)
327			char *user = "USER";
328
329			if (G.iaclen + len > IACBUFSIZE)
330			iacflush();
331
332			putiac(IAC);
333			putiac(SB);
334			putiac(TELOPT_NEW_ENVIRON);
335			putiac(TELQUAL_IS);
336			putiac(NEW_ENV_VAR);
337
338			while (*user)
339			putiac(*user++);
340
341			putiac(NEW_ENV_VALUE);
342
343			while (*autologin)
344			putiac(*autologin++);
345
346			putiac(IAC);
347			putiac(SE);
348			}
349			#endif
350
351			#ifdef CONFIG_FEATURE_AUTOWIDTH
352			static void putiac_naws(byte c, int x, int y)
353			{
354			if (G.iaclen + 9 > IACBUFSIZE)
355			iacflush();
356
357			putiac(IAC);
358			putiac(SB);
359			putiac(c);
360
361			putiac((x >> 8) & 0xff);
362			putiac(x & 0xff);
363			putiac((y >> 8) & 0xff);
364			putiac(y & 0xff);
365
366			putiac(IAC);
367			putiac(SE);
368			}
369			#endif
370
371			/* void putiacstring (subneg strings) */
372
373			/* ******************************* */
374
375			static char const escapecharis[] = "\r\nEscape character is ";
376
377			static void setConMode(void)
378			{
379			if (G.telflags & UF_ECHO)
380			{
381			if (G.charmode == CHM_TRY) {
382			G.charmode = CHM_ON;
383			printf("\r\nEntering character mode%s'^]'.\r\n", escapecharis);
384			rawmode();
385			}
386			}
387			else
388			{
389			if (G.charmode != CHM_OFF) {
390			G.charmode = CHM_OFF;
391			printf("\r\nEntering line mode%s'^C'.\r\n", escapecharis);
392			cookmode();
393			}
394			}
395			}
396
397			/* ******************************* */
398
399			static void will_charmode(void)
400			{
401			G.charmode = CHM_TRY;
402			G.telflags \|= (UF_ECHO \| UF_SGA);
403			setConMode();
404
405			putiac2(DO, TELOPT_ECHO);
406			putiac2(DO, TELOPT_SGA);
407			iacflush();
408			}
409
410			static void do_linemode(void)
411			{
412			G.charmode = CHM_TRY;
413			G.telflags &= ~(UF_ECHO \| UF_SGA);
414			setConMode();
415
416			putiac2(DONT, TELOPT_ECHO);
417			putiac2(DONT, TELOPT_SGA);
418			iacflush();
419			}
420
421			/* ******************************* */
422
423			static void to_notsup(char c)
424			{
425			if (G.telwish == WILL) putiac2(DONT, c);
426			else if (G.telwish == DO) putiac2(WONT, c);
427			}
428
429			static void to_echo(void)
430			{
431			/* if server requests ECHO, don't agree */
432			if (G.telwish == DO) { putiac2(WONT, TELOPT_ECHO); return; }
433			else if (G.telwish == DONT) return;
434
435			if (G.telflags & UF_ECHO)
436			{
437			if (G.telwish == WILL)
438			return;
439			}
440			else
441			if (G.telwish == WONT)
442			return;
443
444			if (G.charmode != CHM_OFF)
445			G.telflags ^= UF_ECHO;
446
447			if (G.telflags & UF_ECHO)
448			putiac2(DO, TELOPT_ECHO);
449			else
450			putiac2(DONT, TELOPT_ECHO);
451
452			setConMode();
453			WriteCS(1, "\r\n"); /* sudden modec */
454			}
455
456			static void to_sga(void)
457			{
458			/* daemon always sends will/wont, client do/dont */
459
460			if (G.telflags & UF_SGA)
461			{
462			if (G.telwish == WILL)
463			return;
464			}
465			else
466			if (G.telwish == WONT)
467			return;
468
469			if ((G.telflags ^= UF_SGA) & UF_SGA) /* toggle */
470			putiac2(DO, TELOPT_SGA);
471			else
472			putiac2(DONT, TELOPT_SGA);
473
474			return;
475			}
476
477			#ifdef CONFIG_FEATURE_TELNET_TTYPE
478			static void to_ttype(void)
479			{
480			/* Tell server we will (or won't) do TTYPE */
481
482			if(ttype)
483			putiac2(WILL, TELOPT_TTYPE);
484			else
485			putiac2(WONT, TELOPT_TTYPE);
486
487			return;
488			}
489			#endif
490
491			#ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
492			static void to_new_environ(void)
493			{
494			/* Tell server we will (or will not) do AUTOLOGIN */
495
496			if (autologin)
497			putiac2(WILL, TELOPT_NEW_ENVIRON);
498			else
499			putiac2(WONT, TELOPT_NEW_ENVIRON);
500
501			return;
502			}
503			#endif
504
505			#ifdef CONFIG_FEATURE_AUTOWIDTH
506			static void to_naws(void)
507			{
508			/* Tell server we will do NAWS */
509			putiac2(WILL, TELOPT_NAWS);
510			return;
511			}
512			#endif
513
514			static void telopt(byte c)
515			{
516			switch (c)
517			{
518			case TELOPT_ECHO: to_echo(); break;
519			case TELOPT_SGA: to_sga(); break;
520			#ifdef CONFIG_FEATURE_TELNET_TTYPE
521			case TELOPT_TTYPE: to_ttype();break;
522			#endif
523			#ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
524			case TELOPT_NEW_ENVIRON: to_new_environ(); break;
525			#endif
526			#ifdef CONFIG_FEATURE_AUTOWIDTH
527			case TELOPT_NAWS: to_naws();
528			putiac_naws(c, win_width, win_height);
529			break;
530			#endif
531			default: to_notsup(c);
532			break;
533			}
534			}
535
536
537			/* ******************************* */
538
539			/* subnegotiation -- ignore all (except TTYPE,NAWS) */
540
541			static int subneg(byte c)
542			{
543			switch (G.telstate)
544			{
545			case TS_SUB1:
546			if (c == IAC)
547			G.telstate = TS_SUB2;
548			#ifdef CONFIG_FEATURE_TELNET_TTYPE
549			else
550			if (c == TELOPT_TTYPE)
551			putiac_subopt(TELOPT_TTYPE,ttype);
552			#endif
553			#ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
554			else
555			if (c == TELOPT_NEW_ENVIRON)
556			putiac_subopt_autologin();
557			#endif
558			break;
559			case TS_SUB2:
560			if (c == SE)
561			return TRUE;
562			G.telstate = TS_SUB1;
563			/* break; */
564			}
565			return FALSE;
566			}
567
568			/* ******************************* */
569
570			static void fgotsig(int sig)
571			{
572			G.gotsig = sig;
573			}
574
575
576			static void rawmode(void)
577			{
578			if (G.do_termios) tcsetattr(0, TCSADRAIN, &G.termios_raw);
579			}
580
581			static void cookmode(void)
582			{
583			if (G.do_termios) tcsetattr(0, TCSADRAIN, &G.termios_def);
584			}
585
586			int telnet_main(int argc, char** argv)
587			{
588			char *host;
589			int port;
590			int len;
591			#ifdef USE_POLL
592			struct pollfd ufds[2];
593			#else
594			fd_set readfds;
595			int maxfd;
596			#endif
597
598			#ifdef CONFIG_FEATURE_AUTOWIDTH
599			get_terminal_width_height(0, &win_width, &win_height);
600			#endif
601
602			#ifdef CONFIG_FEATURE_TELNET_TTYPE
603			ttype = getenv("TERM");
604			#endif
605
606			/* memset(&G, 0, sizeof G); - already is */
607
608			if (tcgetattr(0, &G.termios_def) >= 0) {
609			G.do_termios = 1;
610			G.termios_raw = G.termios_def;
611			cfmakeraw(&G.termios_raw);
612			}
613
614			if (argc < 2)
615			bb_show_usage();
616
617			#ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
618			if (1 & getopt32(argc, argv, "al:", &autologin))
619			autologin = getenv("USER");
620			argv += optind;
621			#else
622			argv++;
623			#endif
624			if (!*argv)
625			bb_show_usage();
626			host = *argv++;
627			port = bb_lookup_port(argv ? argv++ : "telnet", "tcp", 23);
628			if (argv) / extra params?? */
629			bb_show_usage();
630
631			G.netfd = create_and_connect_stream_or_die(host, port);
632
633			setsockopt(G.netfd, SOL_SOCKET, SO_KEEPALIVE, &one, sizeof one);
634
635			signal(SIGINT, fgotsig);
636
637			#ifdef USE_POLL
638			ufds[0].fd = 0; ufds[1].fd = G.netfd;
639			ufds[0].events = ufds[1].events = POLLIN;
640			#else
641			FD_ZERO(&readfds);
642			FD_SET(0, &readfds);
643			FD_SET(G.netfd, &readfds);
644			maxfd = G.netfd + 1;
645			#endif
646
647			while (1) {
648			#ifndef USE_POLL
649			fd_set rfds = readfds;
650
651			switch (select(maxfd, &rfds, NULL, NULL, NULL))
652			#else
653			switch (poll(ufds, 2, -1))
654			#endif
655			{
656			case 0:
657			/* timeout */
658			case -1:
659			/* error, ignore and/or log something, bay go to loop */
660			if (G.gotsig)
661			conescape();
662			else
663			sleep(1);
664			break;
665			default:
666
667			#ifdef USE_POLL
668			if (ufds[0].revents) /* well, should check POLLIN, but ... */
669			#else
670			if (FD_ISSET(0, &rfds))
671			#endif
672			{
673			len = read(0, G.buf, DATABUFSIZE);
674
675			if (len <= 0)
676			doexit(0);
677
678			TRACE(0, ("Read con: %d\n", len));
679
680			handlenetoutput(len);
681			}
682
683			#ifdef USE_POLL
684			if (ufds[1].revents) /* well, should check POLLIN, but ... */
685			#else
686			if (FD_ISSET(G.netfd, &rfds))
687			#endif
688			{
689			len = read(G.netfd, G.buf, DATABUFSIZE);
690
691			if (len <= 0) {
692			WriteCS(1, "Connection closed by foreign host.\r\n");
693			doexit(1);
694			}
695			TRACE(0, ("Read netfd (%d): %d\n", G.netfd, len));
696
697			handlenetinput(len);
698			}
699			}
700			}
701			}