/*
 * Please note: this implementation of openpty() is far from complete.
 * it is just enough for portable OpenSSH's needs.
 */

/*
 * Copyright (c) 2004 Damien Miller <djm@mindrot.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/*
 * Author: Tatu Ylonen <ylo@cs.hut.fi>
 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
 *                    All rights reserved
 * Allocating a pseudo-terminal, and making it the controlling tty.
 *
 * 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".
 */

#include "includes.h"
#if !defined(HAVE_OPENPTY)

#include <sys/types.h>

#include <stdlib.h>

#ifdef HAVE_SYS_STAT_H
# include <sys/stat.h>
#endif
#ifdef HAVE_SYS_IOCTL_H
# include <sys/ioctl.h>
#endif

#ifdef HAVE_FCNTL_H
# include <fcntl.h>
#endif

#ifdef HAVE_UTIL_H
# include <util.h>
#endif /* HAVE_UTIL_H */

#ifdef HAVE_PTY_H
# include <pty.h>
#endif
#if defined(HAVE_DEV_PTMX) && defined(HAVE_SYS_STROPTS_H)
# include <sys/stropts.h>
#endif

#include <signal.h>
#include <string.h>
#include <unistd.h>

#include "misc.h"
#include "log.h"

#ifndef O_NOCTTY
#define O_NOCTTY 0
#endif

#if defined(HAVE_DEV_PTMX) && !defined(HAVE__GETPTY)
static int
openpty_streams(int *amaster, int *aslave)
{
        /*
         * This code is used e.g. on Solaris 2.x.  (Note that Solaris 2.3
         * also has bsd-style ptys, but they simply do not work.)
         */
        int ptm;
        char *pts;
        sshsig_t old_signal;

        if ((ptm = open("/dev/ptmx", O_RDWR | O_NOCTTY)) == -1)
                return (-1);

        /* XXX: need to close ptm on error? */
        old_signal = ssh_signal(SIGCHLD, SIG_DFL);
        if (grantpt(ptm) < 0)
                return (-1);
        ssh_signal(SIGCHLD, old_signal);

        if (unlockpt(ptm) < 0)
                return (-1);

        if ((pts = ptsname(ptm)) == NULL)
                return (-1);
        *amaster = ptm;

        /* Open the slave side. */
        if ((*aslave = open(pts, O_RDWR | O_NOCTTY)) == -1) {
                close(*amaster);
                return (-1);
        }

# if defined(I_FIND) && defined(__SVR4)
        /*
         * If the streams modules have already been pushed then there
         * is no more work to do here.
         */
        if (ioctl(*aslave, I_FIND, "ptem") != 0)
                return 0;
# endif

        /*
         * Try to push the appropriate streams modules, as described
         * in Solaris pts(7).
         */
        ioctl(*aslave, I_PUSH, "ptem");
        ioctl(*aslave, I_PUSH, "ldterm");
# ifndef __hpux
        ioctl(*aslave, I_PUSH, "ttcompat");
# endif /* __hpux */
        return (0);
}
#endif

int
openpty(int *amaster, int *aslave, char *name, struct termios *termp,
   struct winsize *winp)
{
#if defined(HAVE__GETPTY)
        /*
         * _getpty(3) exists in SGI Irix 4.x, 5.x & 6.x -- it generates more
         * pty's automagically when needed
         */
        char *slave;

        if ((slave = _getpty(amaster, O_RDWR, 0622, 0)) == NULL)
                return (-1);

        /* Open the slave side. */
        if ((*aslave = open(slave, O_RDWR | O_NOCTTY)) == -1) {
                close(*amaster);
                return (-1);
        }
        return (0);

#elif defined(HAVE_DEV_PTMX)

#ifdef SSHD_ACQUIRES_CTTY
        /*
         * On some (most? all?) SysV based systems with STREAMS based terminals,
         * sshd will acquire a controlling terminal when it pushes the "ptem"
         * module.  On such platforms, first allocate a sacrificial pty so
         * that sshd already has a controlling terminal before allocating the
         * one that will be passed back to the user process.  This ensures
         * the second pty is not already the controlling terminal for a
         * different session and is available to become controlling terminal
         * for the client's subprocess.  See bugzilla #245 for details.
         */
        int r, fd;
        static int junk_ptyfd = -1, junk_ttyfd;

        r = openpty_streams(amaster, aslave);
        if (junk_ptyfd == -1 && (fd = open(_PATH_TTY, O_RDWR|O_NOCTTY)) >= 0) {
                close(fd);
                junk_ptyfd = *amaster;
                junk_ttyfd = *aslave;
                debug("STREAMS bug workaround pty %d tty %d name %s",
                    junk_ptyfd, junk_ttyfd, ttyname(junk_ttyfd));
        } else
                return r;
#endif

        return openpty_streams(amaster, aslave);

#elif defined(HAVE_DEV_PTS_AND_PTC)
        /* AIX-style pty code. */
        const char *ttname;

        if ((*amaster = open("/dev/ptc", O_RDWR | O_NOCTTY)) == -1)
                return (-1);
        if ((ttname = ttyname(*amaster)) == NULL)
                return (-1);
        if ((*aslave = open(ttname, O_RDWR | O_NOCTTY)) == -1) {
                close(*amaster);
                return (-1);
        }
        return (0);

#else
        /* BSD-style pty code. */
        char ptbuf[64], ttbuf[64];
        int i;
        const char *ptymajors = "pqrstuvwxyzabcdefghijklmno"
            "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        const char *ptyminors = "0123456789abcdef";
        int num_minors = strlen(ptyminors);
        int num_ptys = strlen(ptymajors) * num_minors;
        struct termios tio;

        for (i = 0; i < num_ptys; i++) {
                snprintf(ptbuf, sizeof(ptbuf), "/dev/pty%c%c",
                    ptymajors[i / num_minors], ptyminors[i % num_minors]);
                snprintf(ttbuf, sizeof(ttbuf), "/dev/tty%c%c",
                    ptymajors[i / num_minors], ptyminors[i % num_minors]);

                if ((*amaster = open(ptbuf, O_RDWR | O_NOCTTY)) == -1) {
                        /* Try SCO style naming */
                        snprintf(ptbuf, sizeof(ptbuf), "/dev/ptyp%d", i);
                        snprintf(ttbuf, sizeof(ttbuf), "/dev/ttyp%d", i);
                        if ((*amaster = open(ptbuf, O_RDWR | O_NOCTTY)) == -1)
                                continue;
                }

                /* Open the slave side. */
                if ((*aslave = open(ttbuf, O_RDWR | O_NOCTTY)) == -1) {
                        close(*amaster);
                        return (-1);
                }
                /* set tty modes to a sane state for broken clients */
                if (tcgetattr(*amaster, &tio) != -1) {
                        tio.c_lflag |= (ECHO | ISIG | ICANON);
                        tio.c_oflag |= (OPOST | ONLCR);
                        tio.c_iflag |= ICRNL;
                        tcsetattr(*amaster, TCSANOW, &tio);
                }

                return (0);
        }
        return (-1);
#endif
}

#endif /* !defined(HAVE_OPENPTY) */