/* $OpenBSD: ttymodes.c,v 1.36 2021/01/27 09:26:54 djm 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 "compat.h"
#include "sshbuf.h"
#include "ssherr.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;
        }
}

/*
 * 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
ssh_tty_make_modes(struct ssh *ssh, int fd, struct termios *tiop)
{
        struct termios tio;
        struct sshbuf *buf;
        int r, ibaud, obaud;

        if ((buf = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");

        if (tiop == NULL) {
                if (fd == -1) {
                        debug_f("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. */
        obaud = speed_to_baud(cfgetospeed(&tio));
        ibaud = speed_to_baud(cfgetispeed(&tio));
        if ((r = sshbuf_put_u8(buf, TTY_OP_OSPEED)) != 0 ||
            (r = sshbuf_put_u32(buf, obaud)) != 0 ||
            (r = sshbuf_put_u8(buf, TTY_OP_ISPEED)) != 0 ||
            (r = sshbuf_put_u32(buf, ibaud)) != 0)
                fatal_fr(r, "compose");

        /* Store values of mode flags. */
#define TTYCHAR(NAME, OP) \
        if ((r = sshbuf_put_u8(buf, OP)) != 0 || \
            (r = sshbuf_put_u32(buf, \
            special_char_encode(tio.c_cc[NAME]))) != 0) \
                fatal_fr(r, "compose %s", #NAME);

#define SSH_TTYMODE_IUTF8 42  /* for SSH_BUG_UTF8TTYMODE */

#define TTYMODE(NAME, FIELD, OP) \
        if (OP == SSH_TTYMODE_IUTF8 && (ssh->compat & SSH_BUG_UTF8TTYMODE)) { \
                debug3_f("SSH_BUG_UTF8TTYMODE"); \
        } else if ((r = sshbuf_put_u8(buf, OP)) != 0 || \
            (r = sshbuf_put_u32(buf, ((tio.FIELD & NAME) != 0))) != 0) \
                fatal_fr(r, "compose %s", #NAME);

#include "ttymodes.h"

#undef TTYCHAR
#undef TTYMODE

end:
        /* Mark end of mode data. */
        if ((r = sshbuf_put_u8(buf, TTY_OP_END)) != 0 ||
            (r = sshpkt_put_stringb(ssh, buf)) != 0)
                fatal_fr(r, "compose end");
        sshbuf_free(buf);
}

/*
 * Decodes terminal modes for the terminal referenced by fd in a portable
 * manner from a packet being read.
 */
void
ssh_tty_parse_modes(struct ssh *ssh, int fd)
{
        struct termios tio;
        struct sshbuf *buf;
        const u_char *data;
        u_char opcode;
        u_int baud, u;
        int r, failure = 0;
        size_t len;

        if ((r = sshpkt_get_string_direct(ssh, &data, &len)) != 0)
                fatal_fr(r, "parse");
        if (len == 0)
                return;
        if ((buf = sshbuf_from(data, len)) == NULL) {
                error_f("sshbuf_from failed");
                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;
        }

        while (sshbuf_len(buf) > 0) {
                if ((r = sshbuf_get_u8(buf, &opcode)) != 0)
                        fatal_fr(r, "parse opcode");
                switch (opcode) {
                case TTY_OP_END:
                        goto set;

                case TTY_OP_ISPEED:
                        if ((r = sshbuf_get_u32(buf, &baud)) != 0)
                                fatal_fr(r, "parse ispeed");
                        if (failure != -1 &&
                            cfsetispeed(&tio, baud_to_speed(baud)) == -1)
                                error("cfsetispeed failed for %d", baud);
                        break;

                case TTY_OP_OSPEED:
                        if ((r = sshbuf_get_u32(buf, &baud)) != 0)
                                fatal_fr(r, "parse ospeed");
                        if (failure != -1 &&
                            cfsetospeed(&tio, baud_to_speed(baud)) == -1)
                                error("cfsetospeed failed for %d", baud);
                        break;

#define TTYCHAR(NAME, OP) \
                case OP: \
                        if ((r = sshbuf_get_u32(buf, &u)) != 0) \
                                fatal_fr(r, "parse %s", #NAME); \
                        tio.c_cc[NAME] = special_char_decode(u); \
                        break;
#define TTYMODE(NAME, FIELD, OP) \
                case OP: \
                        if ((r = sshbuf_get_u32(buf, &u)) != 0) \
                                fatal_fr(r, "parse %s", #NAME); \
                        if (u) \
                                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) {
                                if ((r = sshbuf_get_u32(buf, NULL)) != 0)
                                        fatal_fr(r, "parse arg");
                                break;
                        } else {
                                logit_f("unknown opcode %d", opcode);
                                goto set;
                        }
                }
        }

set:
        len = sshbuf_len(buf);
        sshbuf_free(buf);
        if (len > 0) {
                logit_f("%zu bytes left", len);
                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));
}