ttymodes.c - platform/external/openssh - Gitiles

 /* $OpenBSD: ttymodes.c,v 1.26 2006/08/03 03:34:42 deraadt 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 "includes.h"

 #include <sys/types.h>

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

 #include "packet.h"
 #include "log.h"
 #include "ssh1.h"
 #include "compat.h"
 #include "buffer.h"

 #define TTY_OP_END		0
 /*
  * uint32 (u_int) follows speed in SSH1 and SSH2
  */
 #define TTY_OP_ISPEED_PROTO1	192
 #define TTY_OP_OSPEED_PROTO1	193
 #define TTY_OP_ISPEED_PROTO2	128
 #define TTY_OP_OSPEED_PROTO2	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;
 	}
 }

 /*
  * Encode a special character into SSH line format.
  */
 static u_int
 special_char_encode(cc_t c)
 {
 #ifdef _POSIX_VDISABLE
 	if (c == _POSIX_VDISABLE)
 		return 255;
 #endif /* _POSIX_VDISABLE */
 	return c;
 }

 /*
  * Decode a special character from SSH line format.
  */
 static cc_t
 special_char_decode(u_int c)
 {
 #ifdef _POSIX_VDISABLE
 	if (c == 255)
 		return _POSIX_VDISABLE;
 #endif /* _POSIX_VDISABLE */
 	return c;
 }

 /*
  * 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;
 	int tty_op_ospeed, tty_op_ispeed;
 	void (*put_arg)(Buffer *, u_int);

 	buffer_init(&buf);
 	if (compat20) {
 		tty_op_ospeed = TTY_OP_OSPEED_PROTO2;
 		tty_op_ispeed = TTY_OP_ISPEED_PROTO2;
 		put_arg = buffer_put_int;
 	} else {
 		tty_op_ospeed = TTY_OP_OSPEED_PROTO1;
 		tty_op_ispeed = TTY_OP_ISPEED_PROTO1;
 		put_arg = (void (*)(Buffer *, u_int)) buffer_put_char;
 	}

 	if (tiop == NULL) {
 		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));
 	debug3("tty_make_modes: ospeed %d", baud);
 	buffer_put_char(&buf, tty_op_ospeed);
 	buffer_put_int(&buf, baud);
 	baud = speed_to_baud(cfgetispeed(&tio));
 	debug3("tty_make_modes: ispeed %d", baud);
 	buffer_put_char(&buf, tty_op_ispeed);
 	buffer_put_int(&buf, baud);

 	/* Store values of mode flags. */
 #define TTYCHAR(NAME, OP) \
 	debug3("tty_make_modes: %d %d", OP, tio.c_cc[NAME]); \
 	buffer_put_char(&buf, OP); \
 	put_arg(&buf, special_char_encode(tio.c_cc[NAME]));

 #define TTYMODE(NAME, FIELD, OP) \
 	debug3("tty_make_modes: %d %d", OP, ((tio.FIELD & NAME) != 0)); \
 	buffer_put_char(&buf, OP); \
 	put_arg(&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);
 	if (compat20)
 		packet_put_string(buffer_ptr(&buf), buffer_len(&buf));
 	else
 		packet_put_raw(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;
 	u_int (*get_arg)(void);
 	int arg, arg_size;

 	if (compat20) {
 		*n_bytes_ptr = packet_get_int();
 		debug3("tty_parse_modes: SSH2 n_bytes %d", *n_bytes_ptr);
 		if (*n_bytes_ptr == 0)
 			return;
 		get_arg = packet_get_int;
 		arg_size = 4;
 	} else {
 		get_arg = packet_get_char;
 		arg_size = 1;
 	}

 	/*
 	 * 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;

 		/* XXX: future conflict possible */
 		case TTY_OP_ISPEED_PROTO1:
 		case TTY_OP_ISPEED_PROTO2:
 			n_bytes += 4;
 			baud = packet_get_int();
 			debug3("tty_parse_modes: ispeed %d", baud);
 			if (failure != -1 &&
 			    cfsetispeed(&tio, baud_to_speed(baud)) == -1)
 				error("cfsetispeed failed for %d", baud);
 			break;

 		/* XXX: future conflict possible */
 		case TTY_OP_OSPEED_PROTO1:
 		case TTY_OP_OSPEED_PROTO2:
 			n_bytes += 4;
 			baud = packet_get_int();
 			debug3("tty_parse_modes: ospeed %d", baud);
 			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 += arg_size; \
 	  tio.c_cc[NAME] = special_char_decode(get_arg()); \
 	  debug3("tty_parse_modes: %d %d", OP, tio.c_cc[NAME]); \
 	  break;
 #define TTYMODE(NAME, FIELD, OP) \
 	case OP: \
 	  n_bytes += arg_size; \
 	  if ((arg = get_arg())) \
 	    tio.FIELD |= NAME; \
 	  else \
 	    tio.FIELD &= ~NAME;	\
 	  debug3("tty_parse_modes: %d %d", OP, arg); \
 	  break;

 #include "ttymodes.h"

 #undef TTYCHAR
 #undef TTYMODE

 		default:
 			debug("Ignoring unsupported tty mode opcode %d (0x%x)",
 			    opcode, opcode);
 			if (!compat20) {
 				/*
 				 * SSH1:
 				 * Opcodes 1 to 127 are defined to have
 				 * a one-byte argument.
 				 * Opcodes 128 to 159 are defined to have
 				 * an integer argument.
 				 */
 				if (opcode > 0 && opcode < 128) {
 					n_bytes += 1;
 					(void) packet_get_char();
 					break;
 				} else if (opcode >= 128 && opcode < 160) {
 					n_bytes += 4;
 					(void) packet_get_int();
 					break;
 				} else {
 					/*
 					 * It is a truly undefined opcode (160 to 255).
 					 * We have no idea about its arguments.  So we
 					 * must stop parsing.  Note that some data
 					 * may be left in the packet; hopefully there
 					 * is nothing more coming after the mode data.
 					 */
 					logit("parse_tty_modes: unknown opcode %d",
 					    opcode);
 					goto set;
 				}
 			} else {
 				/*
 				 * 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));
 }
	/* $OpenBSD: ttymodes.c,v 1.26 2006/08/03 03:34:42 deraadt 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 "includes.h"

	#include <sys/types.h>

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

	#include "packet.h"
	#include "log.h"
	#include "ssh1.h"
	#include "compat.h"
	#include "buffer.h"

	#define TTY_OP_END 0
	/*
	* uint32 (u_int) follows speed in SSH1 and SSH2
	*/
	#define TTY_OP_ISPEED_PROTO1 192
	#define TTY_OP_OSPEED_PROTO1 193
	#define TTY_OP_ISPEED_PROTO2 128
	#define TTY_OP_OSPEED_PROTO2 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;
	}
	}

	/*
	* Encode a special character into SSH line format.
	*/
	static u_int
	special_char_encode(cc_t c)
	{
	#ifdef _POSIX_VDISABLE
	if (c == _POSIX_VDISABLE)
	return 255;
	#endif /* _POSIX_VDISABLE */
	return c;
	}

	/*
	* Decode a special character from SSH line format.
	*/
	static cc_t
	special_char_decode(u_int c)
	{
	#ifdef _POSIX_VDISABLE
	if (c == 255)
	return _POSIX_VDISABLE;
	#endif /* _POSIX_VDISABLE */
	return c;
	}

	/*
	* 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;
	int tty_op_ospeed, tty_op_ispeed;
	void (put_arg)(Buffer , u_int);

	buffer_init(&buf);
	if (compat20) {
	tty_op_ospeed = TTY_OP_OSPEED_PROTO2;
	tty_op_ispeed = TTY_OP_ISPEED_PROTO2;
	put_arg = buffer_put_int;
	} else {
	tty_op_ospeed = TTY_OP_OSPEED_PROTO1;
	tty_op_ispeed = TTY_OP_ISPEED_PROTO1;
	put_arg = (void ()(Buffer , u_int)) buffer_put_char;
	}

	if (tiop == NULL) {
	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));
	debug3("tty_make_modes: ospeed %d", baud);
	buffer_put_char(&buf, tty_op_ospeed);
	buffer_put_int(&buf, baud);
	baud = speed_to_baud(cfgetispeed(&tio));
	debug3("tty_make_modes: ispeed %d", baud);
	buffer_put_char(&buf, tty_op_ispeed);
	buffer_put_int(&buf, baud);

	/* Store values of mode flags. */
	#define TTYCHAR(NAME, OP) \
	debug3("tty_make_modes: %d %d", OP, tio.c_cc[NAME]); \
	buffer_put_char(&buf, OP); \
	put_arg(&buf, special_char_encode(tio.c_cc[NAME]));

	#define TTYMODE(NAME, FIELD, OP) \
	debug3("tty_make_modes: %d %d", OP, ((tio.FIELD & NAME) != 0)); \
	buffer_put_char(&buf, OP); \
	put_arg(&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);
	if (compat20)
	packet_put_string(buffer_ptr(&buf), buffer_len(&buf));
	else
	packet_put_raw(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;
	u_int (*get_arg)(void);
	int arg, arg_size;

	if (compat20) {
	*n_bytes_ptr = packet_get_int();
	debug3("tty_parse_modes: SSH2 n_bytes %d", *n_bytes_ptr);
	if (*n_bytes_ptr == 0)
	return;
	get_arg = packet_get_int;
	arg_size = 4;
	} else {
	get_arg = packet_get_char;
	arg_size = 1;
	}

	/*
	* 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;

	/* XXX: future conflict possible */
	case TTY_OP_ISPEED_PROTO1:
	case TTY_OP_ISPEED_PROTO2:
	n_bytes += 4;
	baud = packet_get_int();
	debug3("tty_parse_modes: ispeed %d", baud);
	if (failure != -1 &&
	cfsetispeed(&tio, baud_to_speed(baud)) == -1)
	error("cfsetispeed failed for %d", baud);
	break;

	/* XXX: future conflict possible */
	case TTY_OP_OSPEED_PROTO1:
	case TTY_OP_OSPEED_PROTO2:
	n_bytes += 4;
	baud = packet_get_int();
	debug3("tty_parse_modes: ospeed %d", baud);
	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 += arg_size; \
	tio.c_cc[NAME] = special_char_decode(get_arg()); \
	debug3("tty_parse_modes: %d %d", OP, tio.c_cc[NAME]); \
	break;
	#define TTYMODE(NAME, FIELD, OP) \
	case OP: \
	n_bytes += arg_size; \
	if ((arg = get_arg())) \
	tio.FIELD \|= NAME; \
	else \
	tio.FIELD &= ~NAME; \
	debug3("tty_parse_modes: %d %d", OP, arg); \
	break;

	#include "ttymodes.h"

	#undef TTYCHAR
	#undef TTYMODE

	default:
	debug("Ignoring unsupported tty mode opcode %d (0x%x)",
	opcode, opcode);
	if (!compat20) {
	/*
	* SSH1:
	* Opcodes 1 to 127 are defined to have
	* a one-byte argument.
	* Opcodes 128 to 159 are defined to have
	* an integer argument.
	*/
	if (opcode > 0 && opcode < 128) {
	n_bytes += 1;
	(void) packet_get_char();
	break;
	} else if (opcode >= 128 && opcode < 160) {
	n_bytes += 4;
	(void) packet_get_int();
	break;
	} else {
	/*
	* It is a truly undefined opcode (160 to 255).
	* We have no idea about its arguments. So we
	* must stop parsing. Note that some data
	* may be left in the packet; hopefully there
	* is nothing more coming after the mode data.
	*/
	logit("parse_tty_modes: unknown opcode %d",
	opcode);
	goto set;
	}
	} else {
	/*
	* 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));
	}