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Don't send IUTF8 to servers that don't like them.

Some SSH servers eg "ConfD" drop the connection if the client sends the
new IUTF8 (RFC8160) terminal mode even if it's not set.  Add a bug bit
for such servers and avoid sending IUTF8 to them.  ok djm@

/* $OpenBSD: ttymodes.c,v 1.33 2018/02/16 04:43:11 dtucker Exp $ */
/*
 * Author: Tatu Ylonen <ylo@cs.hut.fi>
 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
 *                    All rights reserved
 *
 * As far as I am concerned, the code I have written for this software
 * can be used freely for any purpose.  Any derived versions of this
 * software must be clearly marked as such, and if the derived work is
 * incompatible with the protocol description in the RFC file, it must be
 * called by a name other than "ssh" or "Secure Shell".
 */

/*
 * SSH2 tty modes support by Kevin Steves.
 * Copyright (c) 2001 Kevin Steves.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * Encoding and decoding of terminal modes in a portable way.
 * Much of the format is defined in ttymodes.h; it is included multiple times
 * into this file with the appropriate macro definitions to generate the
 * suitable code.
 */

#include <sys/types.h>

#include <errno.h>
#include <string.h>
#include <termios.h>
#include <stdarg.h>

#include "packet.h"
#include "log.h"
#include "compat.h"
#include "buffer.h"
#include "compat.h"

#define TTY_OP_END		0
/*
 * uint32 (u_int) follows speed.
 */
#define TTY_OP_ISPEED	128
#define TTY_OP_OSPEED	129

/*
 * Converts POSIX speed_t to a baud rate.  The values of the
 * constants for speed_t are not themselves portable.
 */
static int
speed_to_baud(speed_t speed)
{
	switch (speed) {
	case B0:
		return 0;
	case B50:
		return 50;
	case B75:
		return 75;
	case B110:
		return 110;
	case B134:
		return 134;
	case B150:
		return 150;
	case B200:
		return 200;
	case B300:
		return 300;
	case B600:
		return 600;
	case B1200:
		return 1200;
	case B1800:
		return 1800;
	case B2400:
		return 2400;
	case B4800:
		return 4800;
	case B9600:
		return 9600;

#ifdef B19200
	case B19200:
		return 19200;
#else /* B19200 */
#ifdef EXTA
	case EXTA:
		return 19200;
#endif /* EXTA */
#endif /* B19200 */

#ifdef B38400
	case B38400:
		return 38400;
#else /* B38400 */
#ifdef EXTB
	case EXTB:
		return 38400;
#endif /* EXTB */
#endif /* B38400 */

#ifdef B7200
	case B7200:
		return 7200;
#endif /* B7200 */
#ifdef B14400
	case B14400:
		return 14400;
#endif /* B14400 */
#ifdef B28800
	case B28800:
		return 28800;
#endif /* B28800 */
#ifdef B57600
	case B57600:
		return 57600;
#endif /* B57600 */
#ifdef B76800
	case B76800:
		return 76800;
#endif /* B76800 */
#ifdef B115200
	case B115200:
		return 115200;
#endif /* B115200 */
#ifdef B230400
	case B230400:
		return 230400;
#endif /* B230400 */
	default:
		return 9600;
	}
}

/*
 * Converts a numeric baud rate to a POSIX speed_t.
 */
static speed_t
baud_to_speed(int baud)
{
	switch (baud) {
	case 0:
		return B0;
	case 50:
		return B50;
	case 75:
		return B75;
	case 110:
		return B110;
	case 134:
		return B134;
	case 150:
		return B150;
	case 200:
		return B200;
	case 300:
		return B300;
	case 600:
		return B600;
	case 1200:
		return B1200;
	case 1800:
		return B1800;
	case 2400:
		return B2400;
	case 4800:
		return B4800;
	case 9600:
		return B9600;

#ifdef B19200
	case 19200:
		return B19200;
#else /* B19200 */
#ifdef EXTA
	case 19200:
		return EXTA;
#endif /* EXTA */
#endif /* B19200 */

#ifdef B38400
	case 38400:
		return B38400;
#else /* B38400 */
#ifdef EXTB
	case 38400:
		return EXTB;
#endif /* EXTB */
#endif /* B38400 */

#ifdef B7200
	case 7200:
		return B7200;
#endif /* B7200 */
#ifdef B14400
	case 14400:
		return B14400;
#endif /* B14400 */
#ifdef B28800
	case 28800:
		return B28800;
#endif /* B28800 */
#ifdef B57600
	case 57600:
		return B57600;
#endif /* B57600 */
#ifdef B76800
	case 76800:
		return B76800;
#endif /* B76800 */
#ifdef B115200
	case 115200:
		return B115200;
#endif /* B115200 */
#ifdef B230400
	case 230400:
		return B230400;
#endif /* B230400 */
	default:
		return B9600;
	}
}

/*
 * Encodes terminal modes for the terminal referenced by fd
 * or tiop in a portable manner, and appends the modes to a packet
 * being constructed.
 */
void
tty_make_modes(int fd, struct termios *tiop)
{
	struct termios tio;
	int baud;
	Buffer buf;

	buffer_init(&buf);

	if (tiop == NULL) {
		if (fd == -1) {
			debug("tty_make_modes: no fd or tio");
			goto end;
		}
		if (tcgetattr(fd, &tio) == -1) {
			logit("tcgetattr: %.100s", strerror(errno));
			goto end;
		}
	} else
		tio = *tiop;

	/* Store input and output baud rates. */
	baud = speed_to_baud(cfgetospeed(&tio));
	buffer_put_char(&buf, TTY_OP_OSPEED);
	buffer_put_int(&buf, baud);
	baud = speed_to_baud(cfgetispeed(&tio));
	buffer_put_char(&buf, TTY_OP_ISPEED);
	buffer_put_int(&buf, baud);

	/* Store values of mode flags. */
#define TTYCHAR(NAME, OP) \
	buffer_put_char(&buf, OP); \
	buffer_put_int(&buf, tio.c_cc[NAME]);

#define SSH_TTYMODE_IUTF8 42  /* for SSH_BUG_UTF8TTYMODE */

#define TTYMODE(NAME, FIELD, OP) \
	if (OP == SSH_TTYMODE_IUTF8 && (datafellows & SSH_BUG_UTF8TTYMODE)) { \
		debug3("%s: SSH_BUG_UTF8TTYMODE", __func__); \
	} else { \
		buffer_put_char(&buf, OP); \
		buffer_put_int(&buf, ((tio.FIELD & NAME) != 0)); \
	}

#include "ttymodes.h"

#undef TTYCHAR
#undef TTYMODE

end:
	/* Mark end of mode data. */
	buffer_put_char(&buf, TTY_OP_END);
	packet_put_string(buffer_ptr(&buf), buffer_len(&buf));
	buffer_free(&buf);
}

/*
 * Decodes terminal modes for the terminal referenced by fd in a portable
 * manner from a packet being read.
 */
void
tty_parse_modes(int fd, int *n_bytes_ptr)
{
	struct termios tio;
	int opcode, baud;
	int n_bytes = 0;
	int failure = 0;

	*n_bytes_ptr = packet_get_int();
	if (*n_bytes_ptr == 0)
		return;

	/*
	 * Get old attributes for the terminal.  We will modify these
	 * flags. I am hoping that if there are any machine-specific
	 * modes, they will initially have reasonable values.
	 */
	if (tcgetattr(fd, &tio) == -1) {
		logit("tcgetattr: %.100s", strerror(errno));
		failure = -1;
	}

	for (;;) {
		n_bytes += 1;
		opcode = packet_get_char();
		switch (opcode) {
		case TTY_OP_END:
			goto set;

		case TTY_OP_ISPEED:
			n_bytes += 4;
			baud = packet_get_int();
			if (failure != -1 &&
			    cfsetispeed(&tio, baud_to_speed(baud)) == -1)
				error("cfsetispeed failed for %d", baud);
			break;

		case TTY_OP_OSPEED:
			n_bytes += 4;
			baud = packet_get_int();
			if (failure != -1 &&
			    cfsetospeed(&tio, baud_to_speed(baud)) == -1)
				error("cfsetospeed failed for %d", baud);
			break;

#define TTYCHAR(NAME, OP) \
	case OP: \
	  n_bytes += 4; \
	  tio.c_cc[NAME] = packet_get_int(); \
	  break;
#define TTYMODE(NAME, FIELD, OP) \
	case OP: \
	  n_bytes += 4; \
	  if (packet_get_int()) \
	    tio.FIELD |= NAME; \
	  else \
	    tio.FIELD &= ~NAME;	\
	  break;

#include "ttymodes.h"

#undef TTYCHAR
#undef TTYMODE

		default:
			debug("Ignoring unsupported tty mode opcode %d (0x%x)",
			    opcode, opcode);
			/*
			 * SSH2:
			 * Opcodes 1 to 159 are defined to have a uint32
			 * argument.
			 * Opcodes 160 to 255 are undefined and cause parsing
			 * to stop.
			 */
			if (opcode > 0 && opcode < 160) {
				n_bytes += 4;
				(void) packet_get_int();
				break;
			} else {
				logit("parse_tty_modes: unknown opcode %d",
				    opcode);
				goto set;
			}
		}
	}

set:
	if (*n_bytes_ptr != n_bytes) {
		*n_bytes_ptr = n_bytes;
		logit("parse_tty_modes: n_bytes_ptr != n_bytes: %d %d",
		    *n_bytes_ptr, n_bytes);
		return;		/* Don't process bytes passed */
	}
	if (failure == -1)
		return;		/* Packet parsed ok but tcgetattr() failed */

	/* Set the new modes for the terminal. */
	if (tcsetattr(fd, TCSANOW, &tio) == -1)
		logit("Setting tty modes failed: %.100s", strerror(errno));
}