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 "libbb.h"

#ifdef DOTRACE
#define TRACE(x, y) do { if (x) printf y; } while (0)
#else
#define TRACE(x, y)
#endif

enum {
	DATABUFSIZE = 128,
	IACBUFSIZE  = 128,

	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,
};

typedef unsigned char byte;

enum { netfd = 3 };

struct globals {
	int	iaclen; /* could even use byte, but it's a loss on x86 */
	byte	telstate; /* telnet negotiation state from network input */
	byte	telwish;  /* DO, DONT, WILL, WONT */
	byte    charmode;
	byte    telflags;
	byte	do_termios;
#if ENABLE_FEATURE_TELNET_TTYPE
	char	*ttype;
#endif
#if ENABLE_FEATURE_TELNET_AUTOLOGIN
	const char *autologin;
#endif
#if ENABLE_FEATURE_AUTOWIDTH
	unsigned win_width, win_height;
#endif
	/* same buffer used both for network and console read/write */
	char    buf[DATABUFSIZE];
	/* buffer to handle telnet negotiations */
	char    iacbuf[IACBUFSIZE];
	struct termios termios_def;
	struct termios termios_raw;
};
#define G (*(struct globals*)&bb_common_bufsiz1)
void BUG_telnet_globals_too_big(void);
#define INIT_G() do { \
	if (sizeof(G) > COMMON_BUFSIZE) \
		BUG_telnet_globals_too_big(); \
	/* memset(&G, 0, sizeof G); - already is */ \
} while (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);

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

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

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

static void conescape(void)
{
	char b;

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

	write_str(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(STDIN_FILENO, &b, 1) <= 0)
		doexit(EXIT_FAILURE);

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

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

	if (bb_got_signal)
		cookmode();

 rrturn:
	bb_got_signal = 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 too.
	 */

	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(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(STDOUT_FILENO, 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);
}

#if ENABLE_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

#if ENABLE_FEATURE_TELNET_AUTOLOGIN
static void putiac_subopt_autologin(void)
{
	int len = strlen(G.autologin) + 6;	// (2 + 1 + 1 + strlen + 2)
	const 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 (*G.autologin)
		putiac(*G.autologin++);

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

#if ENABLE_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

static char const escapecharis[] ALIGN1 = "\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;
	}
	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();
	write_str(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;

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

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

	if (G.ttype)
		putiac2(WILL, TELOPT_TTYPE);
	else
		putiac2(WONT, TELOPT_TTYPE);
}
#endif

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

	if (G.autologin)
		putiac2(WILL, TELOPT_NEW_ENVIRON);
	else
		putiac2(WONT, TELOPT_NEW_ENVIRON);
}
#endif

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

static void telopt(byte c)
{
	switch (c) {
	case TELOPT_ECHO:
		to_echo(); break;
	case TELOPT_SGA:
		to_sga(); break;
#if ENABLE_FEATURE_TELNET_TTYPE
	case TELOPT_TTYPE:
		to_ttype(); break;
#endif
#if ENABLE_FEATURE_TELNET_AUTOLOGIN
	case TELOPT_NEW_ENVIRON:
		to_new_environ(); break;
#endif
#if ENABLE_FEATURE_AUTOWIDTH
	case TELOPT_NAWS:
		to_naws();
		putiac_naws(c, G.win_width, G.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;
#if ENABLE_FEATURE_TELNET_TTYPE
		else
		if (c == TELOPT_TTYPE)
			putiac_subopt(TELOPT_TTYPE, G.ttype);
#endif
#if ENABLE_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 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);
}

/* poll gives smaller (-70 bytes) code */
#define USE_POLL 1

int telnet_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int telnet_main(int argc UNUSED_PARAM, char **argv)
{
	char *host;
	int port;
	int len;
#ifdef USE_POLL
	struct pollfd ufds[2];
#else
	fd_set readfds;
	int maxfd;
#endif

	INIT_G();

#if ENABLE_FEATURE_AUTOWIDTH
	get_terminal_width_height(0, &G.win_width, &G.win_height);
#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)
				conescape();
			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));
				handlenetoutput(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));
				handlenetinput(len);
			}
		}
	} /* while (1) */
}
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	niro	816	#include "libbb.h"
28	niro	532
29			#ifdef DOTRACE
30			#define TRACE(x, y) do { if (x) printf y; } while (0)
31			#else
32			#define TRACE(x, y)
33			#endif
34
35	niro	816	enum {
36			DATABUFSIZE = 128,
37			IACBUFSIZE = 128,
38	niro	532
39			CHM_TRY = 0,
40			CHM_ON = 1,
41			CHM_OFF = 2,
42
43			UF_ECHO = 0x01,
44			UF_SGA = 0x02,
45
46			TS_0 = 1,
47			TS_IAC = 2,
48			TS_OPT = 3,
49			TS_SUB1 = 4,
50			TS_SUB2 = 5,
51			};
52
53			typedef unsigned char byte;
54
55	niro	816	enum { netfd = 3 };
56
57			struct globals {
58			int iaclen; /* could even use byte, but it's a loss on x86 */
59	niro	532	byte telstate; /* telnet negotiation state from network input */
60			byte telwish; /* DO, DONT, WILL, WONT */
61			byte charmode;
62			byte telflags;
63			byte do_termios;
64	niro	816	#if ENABLE_FEATURE_TELNET_TTYPE
65			char *ttype;
66			#endif
67			#if ENABLE_FEATURE_TELNET_AUTOLOGIN
68			const char *autologin;
69			#endif
70			#if ENABLE_FEATURE_AUTOWIDTH
71			unsigned win_width, win_height;
72			#endif
73			/* same buffer used both for network and console read/write */
74			char buf[DATABUFSIZE];
75	niro	532	/* buffer to handle telnet negotiations */
76			char iacbuf[IACBUFSIZE];
77			struct termios termios_def;
78			struct termios termios_raw;
79	niro	816	};
80			#define G ((struct globals)&bb_common_bufsiz1)
81			void BUG_telnet_globals_too_big(void);
82			#define INIT_G() do { \
83			if (sizeof(G) > COMMON_BUFSIZE) \
84			BUG_telnet_globals_too_big(); \
85			/* memset(&G, 0, sizeof G); - already is */ \
86			} while (0)
87	niro	532
88			/* Function prototypes */
89			static void rawmode(void);
90			static void cookmode(void);
91			static void do_linemode(void);
92			static void will_charmode(void);
93			static void telopt(byte c);
94			static int subneg(byte c);
95
96	niro	816	static void iacflush(void)
97			{
98			write(netfd, G.iacbuf, G.iaclen);
99			G.iaclen = 0;
100			}
101	niro	532
102	niro	816	#define write_str(fd, str) write(fd, str, sizeof(str) - 1)
103	niro	532
104	niro	816	static void doexit(int ev) NORETURN;
105	niro	532	static void doexit(int ev)
106			{
107			cookmode();
108			exit(ev);
109			}
110
111			static void conescape(void)
112			{
113			char b;
114
115	niro	816	if (bb_got_signal) /* came from line mode... go raw */
116	niro	532	rawmode();
117
118	niro	816	write_str(1, "\r\nConsole escape. Commands are:\r\n\n"
119	niro	532	" l go to line mode\r\n"
120			" c go to character mode\r\n"
121			" z suspend telnet\r\n"
122			" e exit telnet\r\n");
123
124	niro	816	if (read(STDIN_FILENO, &b, 1) <= 0)
125			doexit(EXIT_FAILURE);
126	niro	532
127	niro	816	switch (b) {
128	niro	532	case 'l':
129	niro	816	if (!bb_got_signal) {
130	niro	532	do_linemode();
131			goto rrturn;
132			}
133			break;
134			case 'c':
135	niro	816	if (bb_got_signal) {
136	niro	532	will_charmode();
137			goto rrturn;
138			}
139			break;
140			case 'z':
141			cookmode();
142			kill(0, SIGTSTP);
143			rawmode();
144			break;
145			case 'e':
146	niro	816	doexit(EXIT_SUCCESS);
147	niro	532	}
148
149	niro	816	write_str(1, "continuing...\r\n");
150	niro	532
151	niro	816	if (bb_got_signal)
152	niro	532	cookmode();
153
154			rrturn:
155	niro	816	bb_got_signal = 0;
156	niro	532
157			}
158	niro	816
159	niro	532	static void handlenetoutput(int len)
160			{
161	niro	816	/* here we could do smart tricks how to handle 0xFF:s in output
162			* stream like writing twice every sequence of FF:s (thus doing
163			* many write()s. But I think interactive telnet application does
164			* not need to be 100% 8-bit clean, so changing every 0xff:s to
165			* 0x7f:s
166	niro	532	*
167	niro	816	* 2002-mar-21, Przemyslaw Czerpak (druzus@polbox.com)
168			* I don't agree.
169			* first - I cannot use programs like sz/rz
170			* second - the 0x0D is sent as one character and if the next
171			* char is 0x0A then it's eaten by a server side.
172			* third - whay doy you have to make 'many write()s'?
173			* I don't understand.
174			* So I implemented it. It's realy useful for me. I hope that
175			* others people will find it interesting too.
176	niro	532	*/
177
178			int i, j;
179			byte * p = (byte*)G.buf;
180			byte outbuf[4*DATABUFSIZE];
181
182	niro	816	for (i = len, j = 0; i > 0; i--, p++) {
183			if (*p == 0x1d) {
184	niro	532	conescape();
185			return;
186			}
187			outbuf[j++] = *p;
188			if (*p == 0xff)
189			outbuf[j++] = 0xff;
190			else if (*p == 0x0d)
191			outbuf[j++] = 0x00;
192			}
193	niro	816	if (j > 0)
194			write(netfd, outbuf, j);
195	niro	532	}
196
197			static void handlenetinput(int len)
198			{
199			int i;
200			int cstart = 0;
201
202	niro	816	for (i = 0; i < len; i++) {
203	niro	532	byte c = G.buf[i];
204
205	niro	816	if (G.telstate == 0) { /* most of the time state == 0 */
206			if (c == IAC) {
207	niro	532	cstart = i;
208			G.telstate = TS_IAC;
209			}
210	niro	816	} else
211			switch (G.telstate) {
212			case TS_0:
213			if (c == IAC)
214			G.telstate = TS_IAC;
215			else
216			G.buf[cstart++] = c;
217			break;
218	niro	532
219	niro	816	case TS_IAC:
220			if (c == IAC) { /* IAC IAC -> 0xFF */
221			G.buf[cstart++] = c;
222			G.telstate = TS_0;
223			break;
224			}
225			/* else */
226			switch (c) {
227			case SB:
228			G.telstate = TS_SUB1;
229			break;
230			case DO:
231			case DONT:
232			case WILL:
233			case WONT:
234			G.telwish = c;
235			G.telstate = TS_OPT;
236			break;
237			default:
238			G.telstate = TS_0; /* DATA MARK must be added later */
239			}
240			break;
241			case TS_OPT: /* WILL, WONT, DO, DONT */
242			telopt(c);
243			G.telstate = TS_0;
244			break;
245			case TS_SUB1: /* Subnegotiation */
246			case TS_SUB2: /* Subnegotiation */
247			if (subneg(c))
248			G.telstate = TS_0;
249			break;
250			}
251	niro	532	}
252	niro	816	if (G.telstate) {
253			if (G.iaclen) iacflush();
254	niro	532	if (G.telstate == TS_0) G.telstate = 0;
255			len = cstart;
256			}
257
258			if (len)
259	niro	816	write(STDOUT_FILENO, G.buf, len);
260	niro	532	}
261
262			static void putiac(int c)
263			{
264			G.iacbuf[G.iaclen++] = c;
265			}
266
267			static void putiac2(byte wwdd, byte c)
268			{
269			if (G.iaclen + 3 > IACBUFSIZE)
270			iacflush();
271
272			putiac(IAC);
273			putiac(wwdd);
274			putiac(c);
275			}
276
277	niro	816	#if ENABLE_FEATURE_TELNET_TTYPE
278	niro	532	static void putiac_subopt(byte c, char *str)
279			{
280			int len = strlen(str) + 6; // ( 2 + 1 + 1 + strlen + 2 )
281
282			if (G.iaclen + len > IACBUFSIZE)
283			iacflush();
284
285			putiac(IAC);
286			putiac(SB);
287			putiac(c);
288			putiac(0);
289
290			while (*str)
291			putiac(*str++);
292
293			putiac(IAC);
294			putiac(SE);
295			}
296			#endif
297
298	niro	816	#if ENABLE_FEATURE_TELNET_AUTOLOGIN
299	niro	532	static void putiac_subopt_autologin(void)
300			{
301	niro	816	int len = strlen(G.autologin) + 6; // (2 + 1 + 1 + strlen + 2)
302			const char *user = "USER";
303	niro	532
304			if (G.iaclen + len > IACBUFSIZE)
305			iacflush();
306
307			putiac(IAC);
308			putiac(SB);
309			putiac(TELOPT_NEW_ENVIRON);
310			putiac(TELQUAL_IS);
311			putiac(NEW_ENV_VAR);
312
313			while (*user)
314			putiac(*user++);
315
316			putiac(NEW_ENV_VALUE);
317
318	niro	816	while (*G.autologin)
319			putiac(*G.autologin++);
320	niro	532
321			putiac(IAC);
322			putiac(SE);
323			}
324			#endif
325
326	niro	816	#if ENABLE_FEATURE_AUTOWIDTH
327	niro	532	static void putiac_naws(byte c, int x, int y)
328			{
329			if (G.iaclen + 9 > IACBUFSIZE)
330			iacflush();
331
332			putiac(IAC);
333			putiac(SB);
334			putiac(c);
335
336			putiac((x >> 8) & 0xff);
337			putiac(x & 0xff);
338			putiac((y >> 8) & 0xff);
339			putiac(y & 0xff);
340
341			putiac(IAC);
342			putiac(SE);
343			}
344			#endif
345
346	niro	816	static char const escapecharis[] ALIGN1 = "\r\nEscape character is ";
347	niro	532
348			static void setConMode(void)
349			{
350	niro	816	if (G.telflags & UF_ECHO) {
351	niro	532	if (G.charmode == CHM_TRY) {
352			G.charmode = CHM_ON;
353			printf("\r\nEntering character mode%s'^]'.\r\n", escapecharis);
354			rawmode();
355			}
356	niro	816	} else {
357	niro	532	if (G.charmode != CHM_OFF) {
358			G.charmode = CHM_OFF;
359			printf("\r\nEntering line mode%s'^C'.\r\n", escapecharis);
360			cookmode();
361			}
362			}
363			}
364
365			static void will_charmode(void)
366			{
367			G.charmode = CHM_TRY;
368			G.telflags \|= (UF_ECHO \| UF_SGA);
369			setConMode();
370
371			putiac2(DO, TELOPT_ECHO);
372			putiac2(DO, TELOPT_SGA);
373			iacflush();
374			}
375
376			static void do_linemode(void)
377			{
378			G.charmode = CHM_TRY;
379			G.telflags &= ~(UF_ECHO \| UF_SGA);
380			setConMode();
381
382			putiac2(DONT, TELOPT_ECHO);
383			putiac2(DONT, TELOPT_SGA);
384			iacflush();
385			}
386
387			static void to_notsup(char c)
388			{
389	niro	816	if (G.telwish == WILL)
390			putiac2(DONT, c);
391			else if (G.telwish == DO)
392			putiac2(WONT, c);
393	niro	532	}
394
395			static void to_echo(void)
396			{
397			/* if server requests ECHO, don't agree */
398	niro	816	if (G.telwish == DO) {
399			putiac2(WONT, TELOPT_ECHO);
400			return;
401			}
402			if (G.telwish == DONT)
403			return;
404	niro	532
405	niro	816	if (G.telflags & UF_ECHO) {
406	niro	532	if (G.telwish == WILL)
407			return;
408	niro	816	} else if (G.telwish == WONT)
409			return;
410	niro	532
411			if (G.charmode != CHM_OFF)
412			G.telflags ^= UF_ECHO;
413
414			if (G.telflags & UF_ECHO)
415			putiac2(DO, TELOPT_ECHO);
416			else
417			putiac2(DONT, TELOPT_ECHO);
418
419			setConMode();
420	niro	816	write_str(1, "\r\n"); /* sudden modec */
421	niro	532	}
422
423			static void to_sga(void)
424			{
425			/* daemon always sends will/wont, client do/dont */
426
427	niro	816	if (G.telflags & UF_SGA) {
428	niro	532	if (G.telwish == WILL)
429			return;
430	niro	816	} else if (G.telwish == WONT)
431			return;
432	niro	532
433	niro	816	G.telflags ^= UF_SGA; /* toggle */
434			if (G.telflags & UF_SGA)
435	niro	532	putiac2(DO, TELOPT_SGA);
436			else
437			putiac2(DONT, TELOPT_SGA);
438			}
439
440	niro	816	#if ENABLE_FEATURE_TELNET_TTYPE
441	niro	532	static void to_ttype(void)
442			{
443			/* Tell server we will (or won't) do TTYPE */
444
445	niro	816	if (G.ttype)
446	niro	532	putiac2(WILL, TELOPT_TTYPE);
447			else
448			putiac2(WONT, TELOPT_TTYPE);
449			}
450			#endif
451
452	niro	816	#if ENABLE_FEATURE_TELNET_AUTOLOGIN
453	niro	532	static void to_new_environ(void)
454			{
455			/* Tell server we will (or will not) do AUTOLOGIN */
456
457	niro	816	if (G.autologin)
458	niro	532	putiac2(WILL, TELOPT_NEW_ENVIRON);
459			else
460			putiac2(WONT, TELOPT_NEW_ENVIRON);
461			}
462			#endif
463
464	niro	816	#if ENABLE_FEATURE_AUTOWIDTH
465	niro	532	static void to_naws(void)
466			{
467			/* Tell server we will do NAWS */
468			putiac2(WILL, TELOPT_NAWS);
469			}
470			#endif
471
472			static void telopt(byte c)
473			{
474	niro	816	switch (c) {
475			case TELOPT_ECHO:
476			to_echo(); break;
477			case TELOPT_SGA:
478			to_sga(); break;
479			#if ENABLE_FEATURE_TELNET_TTYPE
480			case TELOPT_TTYPE:
481			to_ttype(); break;
482	niro	532	#endif
483	niro	816	#if ENABLE_FEATURE_TELNET_AUTOLOGIN
484			case TELOPT_NEW_ENVIRON:
485			to_new_environ(); break;
486	niro	532	#endif
487	niro	816	#if ENABLE_FEATURE_AUTOWIDTH
488			case TELOPT_NAWS:
489			to_naws();
490			putiac_naws(c, G.win_width, G.win_height);
491			break;
492	niro	532	#endif
493	niro	816	default:
494			to_notsup(c);
495			break;
496	niro	532	}
497			}
498
499			/* subnegotiation -- ignore all (except TTYPE,NAWS) */
500			static int subneg(byte c)
501			{
502	niro	816	switch (G.telstate) {
503	niro	532	case TS_SUB1:
504			if (c == IAC)
505			G.telstate = TS_SUB2;
506	niro	816	#if ENABLE_FEATURE_TELNET_TTYPE
507	niro	532	else
508			if (c == TELOPT_TTYPE)
509	niro	816	putiac_subopt(TELOPT_TTYPE, G.ttype);
510	niro	532	#endif
511	niro	816	#if ENABLE_FEATURE_TELNET_AUTOLOGIN
512	niro	532	else
513			if (c == TELOPT_NEW_ENVIRON)
514			putiac_subopt_autologin();
515			#endif
516			break;
517			case TS_SUB2:
518			if (c == SE)
519			return TRUE;
520			G.telstate = TS_SUB1;
521			/* break; */
522			}
523			return FALSE;
524			}
525
526			static void rawmode(void)
527			{
528	niro	816	if (G.do_termios)
529			tcsetattr(0, TCSADRAIN, &G.termios_raw);
530	niro	532	}
531
532			static void cookmode(void)
533			{
534	niro	816	if (G.do_termios)
535			tcsetattr(0, TCSADRAIN, &G.termios_def);
536	niro	532	}
537
538	niro	816	/* poll gives smaller (-70 bytes) code */
539			#define USE_POLL 1
540
541			int telnet_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
542			int telnet_main(int argc UNUSED_PARAM, char **argv)
543	niro	532	{
544			char *host;
545			int port;
546			int len;
547			#ifdef USE_POLL
548			struct pollfd ufds[2];
549			#else
550			fd_set readfds;
551			int maxfd;
552			#endif
553
554	niro	816	INIT_G();
555
556			#if ENABLE_FEATURE_AUTOWIDTH
557			get_terminal_width_height(0, &G.win_width, &G.win_height);
558	niro	532	#endif
559
560	niro	816	#if ENABLE_FEATURE_TELNET_TTYPE
561			G.ttype = getenv("TERM");
562	niro	532	#endif
563
564			if (tcgetattr(0, &G.termios_def) >= 0) {
565			G.do_termios = 1;
566			G.termios_raw = G.termios_def;
567			cfmakeraw(&G.termios_raw);
568			}
569
570	niro	816	#if ENABLE_FEATURE_TELNET_AUTOLOGIN
571			if (1 & getopt32(argv, "al:", &G.autologin))
572			G.autologin = getenv("USER");
573	niro	532	argv += optind;
574			#else
575			argv++;
576			#endif
577			if (!*argv)
578			bb_show_usage();
579			host = *argv++;
580			port = bb_lookup_port(argv ? argv++ : "telnet", "tcp", 23);
581			if (argv) / extra params?? */
582			bb_show_usage();
583
584	niro	816	xmove_fd(create_and_connect_stream_or_die(host, port), netfd);
585	niro	532
586	niro	816	setsockopt(netfd, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1));
587	niro	532
588	niro	816	signal(SIGINT, record_signo);
589	niro	532
590			#ifdef USE_POLL
591	niro	816	ufds[0].fd = 0; ufds[1].fd = netfd;
592	niro	532	ufds[0].events = ufds[1].events = POLLIN;
593			#else
594			FD_ZERO(&readfds);
595	niro	816	FD_SET(STDIN_FILENO, &readfds);
596			FD_SET(netfd, &readfds);
597			maxfd = netfd + 1;
598	niro	532	#endif
599
600			while (1) {
601			#ifndef USE_POLL
602			fd_set rfds = readfds;
603
604			switch (select(maxfd, &rfds, NULL, NULL, NULL))
605			#else
606			switch (poll(ufds, 2, -1))
607			#endif
608			{
609			case 0:
610			/* timeout */
611			case -1:
612			/* error, ignore and/or log something, bay go to loop */
613	niro	816	if (bb_got_signal)
614	niro	532	conescape();
615			else
616			sleep(1);
617			break;
618			default:
619
620			#ifdef USE_POLL
621			if (ufds[0].revents) /* well, should check POLLIN, but ... */
622			#else
623	niro	816	if (FD_ISSET(STDIN_FILENO, &rfds))
624	niro	532	#endif
625			{
626	niro	816	len = read(STDIN_FILENO, G.buf, DATABUFSIZE);
627	niro	532	if (len <= 0)
628	niro	816	doexit(EXIT_SUCCESS);
629	niro	532	TRACE(0, ("Read con: %d\n", len));
630			handlenetoutput(len);
631			}
632
633			#ifdef USE_POLL
634			if (ufds[1].revents) /* well, should check POLLIN, but ... */
635			#else
636	niro	816	if (FD_ISSET(netfd, &rfds))
637	niro	532	#endif
638			{
639	niro	816	len = read(netfd, G.buf, DATABUFSIZE);
640	niro	532	if (len <= 0) {
641	niro	816	write_str(1, "Connection closed by foreign host\r\n");
642			doexit(EXIT_FAILURE);
643	niro	532	}
644	niro	816	TRACE(0, ("Read netfd (%d): %d\n", netfd, len));
645	niro	532	handlenetinput(len);
646			}
647			}
648	niro	816	} /* while (1) */
649	niro	532	}