/*      $NetBSD: sys_term.c,v 1.51 2025/06/27 21:36:23 andvar Exp $     */

/*
 * Copyright (c) 1989, 1993
 *      The Regents of the University of California.  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.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
 */

#include <sys/cdefs.h>
#ifndef lint
#if 0
static char sccsid[] = "@(#)sys_term.c  8.4+1 (Berkeley) 5/30/95";
#else
__RCSID("$NetBSD: sys_term.c,v 1.51 2025/06/27 21:36:23 andvar Exp $");
#endif
#endif /* not lint */

#include "telnetd.h"
#include "pathnames.h"

#include <util.h>
#include <vis.h>

#ifdef SUPPORT_UTMP
#include <utmp.h>
#endif
#ifdef SUPPORT_UTMPX
#include <utmpx.h>
#endif

struct termios termbuf, termbuf2;       /* pty control structure */

void getptyslave(void);
int cleanopen(char *);
char **addarg(char **, const char *);
void scrub_env(void);
int getent(char *, char *);
char *getstr(const char *, char **);
#ifdef KRB5
extern void kerberos5_cleanup(void);
#endif

/*
 * init_termbuf()
 * copy_termbuf(cp)
 * set_termbuf()
 *
 * These three routines are used to get and set the "termbuf" structure
 * to and from the kernel.  init_termbuf() gets the current settings.
 * copy_termbuf() hands in a new "termbuf" to write to the kernel, and
 * set_termbuf() writes the structure into the kernel.
 */

void
init_termbuf(void)
{
        (void) tcgetattr(pty, &termbuf);
        termbuf2 = termbuf;
}

#if     defined(LINEMODE) && defined(TIOCPKT_IOCTL)
void
copy_termbuf(char *cp, int len)
{
        if ((size_t)len > sizeof(termbuf))
                len = sizeof(termbuf);
        memmove((char *)&termbuf, cp, len);
        termbuf2 = termbuf;
}
#endif  /* defined(LINEMODE) && defined(TIOCPKT_IOCTL) */

void
set_termbuf(void)
{
        /*
         * Only make the necessary changes.
         */
        if (memcmp((char *)&termbuf, (char *)&termbuf2, sizeof(termbuf)))
                (void) tcsetattr(pty, TCSANOW, &termbuf);
}


/*
 * spcset(func, valp, valpp)
 *
 * This function takes various special characters (func), and
 * sets *valp to the current value of that character, and
 * *valpp to point to where in the "termbuf" structure that
 * value is kept.
 *
 * It returns the SLC_ level of support for this function.
 */


int
spcset(int func, cc_t *valp, cc_t **valpp)
{

#define setval(a, b)    *valp = termbuf.c_cc[a]; \
                        *valpp = &termbuf.c_cc[a]; \
                        return(b);
#define defval(a) *valp = ((cc_t)a); *valpp = (cc_t *)0; return(SLC_DEFAULT);

        switch(func) {
        case SLC_EOF:
                setval(VEOF, SLC_VARIABLE);
        case SLC_EC:
                setval(VERASE, SLC_VARIABLE);
        case SLC_EL:
                setval(VKILL, SLC_VARIABLE);
        case SLC_IP:
                setval(VINTR, SLC_VARIABLE|SLC_FLUSHIN|SLC_FLUSHOUT);
        case SLC_ABORT:
                setval(VQUIT, SLC_VARIABLE|SLC_FLUSHIN|SLC_FLUSHOUT);
        case SLC_XON:
                setval(VSTART, SLC_VARIABLE);
        case SLC_XOFF:
                setval(VSTOP, SLC_VARIABLE);
        case SLC_EW:
                setval(VWERASE, SLC_VARIABLE);
        case SLC_RP:
                setval(VREPRINT, SLC_VARIABLE);
        case SLC_LNEXT:
                setval(VLNEXT, SLC_VARIABLE);
        case SLC_AO:
                setval(VDISCARD, SLC_VARIABLE|SLC_FLUSHOUT);
        case SLC_SUSP:
                setval(VSUSP, SLC_VARIABLE|SLC_FLUSHIN);
        case SLC_FORW1:
                setval(VEOL, SLC_VARIABLE);
        case SLC_FORW2:
                setval(VEOL2, SLC_VARIABLE);
        case SLC_AYT:
                setval(VSTATUS, SLC_VARIABLE);

        case SLC_BRK:
        case SLC_SYNCH:
        case SLC_EOR:
                defval(0);

        default:
                *valp = 0;
                *valpp = 0;
                return(SLC_NOSUPPORT);
        }
}


/*
 * getpty()
 *
 * Allocate a pty.  As a side effect, the external character
 * array "line" contains the name of the slave side.
 *
 * Returns the file descriptor of the opened pty.
 */

static int ptyslavefd; /* for cleanopen() */

int
getpty(int *ptynum)
{
        int ptyfd;

        ptyfd = openpty(ptynum, &ptyslavefd, line, NULL, NULL);
        if (ptyfd == 0)
                return *ptynum;
        ptyslavefd = -1;
        return (-1);
}

#ifdef  LINEMODE
/*
 * tty_flowmode()       Find out if flow control is enabled or disabled.
 * tty_linemode()       Find out if linemode (external processing) is enabled.
 * tty_setlinemod(on)   Turn on/off linemode.
 * tty_isecho()         Find out if echoing is turned on.
 * tty_setecho(on)      Enable/disable character echoing.
 * tty_israw()          Find out if terminal is in RAW mode.
 * tty_binaryin(on)     Turn on/off BINARY on input.
 * tty_binaryout(on)    Turn on/off BINARY on output.
 * tty_isediting()      Find out if line editing is enabled.
 * tty_istrapsig()      Find out if signal trapping is enabled.
 * tty_setedit(on)      Turn on/off line editing.
 * tty_setsig(on)       Turn on/off signal trapping.
 * tty_issofttab()      Find out if tab expansion is enabled.
 * tty_setsofttab(on)   Turn on/off soft tab expansion.
 * tty_islitecho()      Find out if typed control chars are echoed literally
 * tty_setlitecho()     Turn on/off literal echo of control chars
 * tty_tspeed(val)      Set transmit speed to val.
 * tty_rspeed(val)      Set receive speed to val.
 */


int
tty_linemode(void)
{
        return(termbuf.c_lflag & EXTPROC);
}

void
tty_setlinemode(int on)
{
        set_termbuf();
        (void) ioctl(pty, TIOCEXT, (char *)&on);
        init_termbuf();
}
#endif  /* LINEMODE */

int
tty_isecho(void)
{
        return (termbuf.c_lflag & ECHO);
}

int
tty_flowmode(void)
{
        return((termbuf.c_iflag & IXON) ? 1 : 0);
}

int
tty_restartany(void)
{
        return((termbuf.c_iflag & IXANY) ? 1 : 0);
}

void
tty_setecho(int on)
{
        if (on)
                termbuf.c_lflag |= ECHO;
        else
                termbuf.c_lflag &= ~ECHO;
}

int
tty_israw(void)
{
        return(!(termbuf.c_lflag & ICANON));
}

void
tty_binaryin(int on)
{
        if (on) {
                termbuf.c_iflag &= ~ISTRIP;
        } else {
                termbuf.c_iflag |= ISTRIP;
        }
}

void
tty_binaryout(int on)
{
        if (on) {
                termbuf.c_cflag &= ~(CSIZE|PARENB);
                termbuf.c_cflag |= CS8;
                termbuf.c_oflag &= ~OPOST;
        } else {
                termbuf.c_cflag &= ~CSIZE;
                termbuf.c_cflag |= CS7|PARENB;
                termbuf.c_oflag |= OPOST;
        }
}

int
tty_isbinaryin(void)
{
        return(!(termbuf.c_iflag & ISTRIP));
}

int
tty_isbinaryout(void)
{
        return(!(termbuf.c_oflag&OPOST));
}

#ifdef  LINEMODE
int
tty_isediting(void)
{
        return(termbuf.c_lflag & ICANON);
}

int
tty_istrapsig(void)
{
        return(termbuf.c_lflag & ISIG);
}

void
tty_setedit(int on)
{
        if (on)
                termbuf.c_lflag |= ICANON;
        else
                termbuf.c_lflag &= ~ICANON;
}

void
tty_setsig(int on)
{
        if (on)
                termbuf.c_lflag |= ISIG;
        else
                termbuf.c_lflag &= ~ISIG;
}
#endif  /* LINEMODE */

int
tty_issofttab(void)
{
# ifdef OXTABS
        return (termbuf.c_oflag & OXTABS);
# endif
# ifdef TABDLY
        return ((termbuf.c_oflag & TABDLY) == TAB3);
# endif
}

void
tty_setsofttab(int on)
{
        if (on) {
# ifdef OXTABS
                termbuf.c_oflag |= OXTABS;
# endif
# ifdef TABDLY
                termbuf.c_oflag &= ~TABDLY;
                termbuf.c_oflag |= TAB3;
# endif
        } else {
# ifdef OXTABS
                termbuf.c_oflag &= ~OXTABS;
# endif
# ifdef TABDLY
                termbuf.c_oflag &= ~TABDLY;
                termbuf.c_oflag |= TAB0;
# endif
        }
}

int
tty_islitecho(void)
{
# ifdef ECHOCTL
        return (!(termbuf.c_lflag & ECHOCTL));
# endif
# ifdef TCTLECH
        return (!(termbuf.c_lflag & TCTLECH));
# endif
# if    !defined(ECHOCTL) && !defined(TCTLECH)
        return (0);     /* assumes ctl chars are echoed '^x' */
# endif
}

void
tty_setlitecho(int on)
{
# ifdef ECHOCTL
        if (on)
                termbuf.c_lflag &= ~ECHOCTL;
        else
                termbuf.c_lflag |= ECHOCTL;
# endif
# ifdef TCTLECH
        if (on)
                termbuf.c_lflag &= ~TCTLECH;
        else
                termbuf.c_lflag |= TCTLECH;
# endif
}

int
tty_iscrnl(void)
{
        return (termbuf.c_iflag & ICRNL);
}

void
tty_tspeed(int val)
{
        cfsetospeed(&termbuf, val);
}

void
tty_rspeed(int val)
{
        cfsetispeed(&termbuf, val);
}




/*
 * getptyslave()
 *
 * Open the slave side of the pty, and do any initialization
 * that is necessary.  The return value is a file descriptor
 * for the slave side.
 */
extern int def_tspeed, def_rspeed;
        extern int def_row, def_col;

void
getptyslave(void)
{
        int t = -1;

#ifdef  LINEMODE
        int waslm;
#endif
        struct winsize ws;
        /*
         * Opening the slave side may cause initialization of the
         * kernel tty structure.  We need remember the state of
         *      if linemode was turned on
         *      terminal window size
         *      terminal speed
         * so that we can re-set them if we need to.
         */
#ifdef  LINEMODE
        waslm = tty_linemode();
#endif

        /*
         * Make sure that we don't have a controlling tty, and
         * that we are the session (process group) leader.
         */
        t = open(_PATH_TTY, O_RDWR);
        if (t >= 0) {
                (void) ioctl(t, TIOCNOTTY, (char *)0);
                (void) close(t);
        }



        t = cleanopen(line);
        if (t < 0)
                fatalperror(net, line);


        /*
         * set up the tty modes as we like them to be.
         */
        init_termbuf();
        if (def_row || def_col) {
                memset((char *)&ws, 0, sizeof(ws));
                ws.ws_col = def_col;
                ws.ws_row = def_row;
                (void)ioctl(t, TIOCSWINSZ, (char *)&ws);
        }

        /*
         * Settings for sgtty based systems
         */

        /*
         * Settings for all other termios/termio based
         * systems, other than 4.4BSD.  In 4.4BSD the
         * kernel does the initial terminal setup.
         */
        tty_rspeed((def_rspeed > 0) ? def_rspeed : 9600);
        tty_tspeed((def_tspeed > 0) ? def_tspeed : 9600);
#ifdef  LINEMODE
        if (waslm)
                tty_setlinemode(1);
#endif  /* LINEMODE */

        /*
         * Set the tty modes, and make this our controlling tty.
         */
        set_termbuf();
        if (login_tty(t) == -1)
                fatalperror(net, "login_tty");
        if (net > 2)
                (void) close(net);
        if (pty > 2) {
                (void) close(pty);
                pty = -1;
        }
}

/*
 * Open the specified slave side of the pty,
 * making sure that we have a clean tty.
 */
int
cleanopen(char *ttyline)
{
        return ptyslavefd;
}

/*
 * startslave(host)
 *
 * Given a hostname, do whatever
 * is necessary to startup the login process on the slave side of the pty.
 */

/* ARGSUSED */
void
startslave(char *host, int autologin, char *autoname)
{
        int i;

#ifdef AUTHENTICATION
        if (!autoname || !autoname[0])
                autologin = 0;

        if (autologin < auth_level) {
                fatal(net, "Authorization failed");
                exit(1);
        }
#endif


        if ((i = fork()) < 0)
                fatalperror(net, "fork");
        if (i) {
        } else {
                getptyslave();
                start_login(host, autologin, autoname);
                /*NOTREACHED*/
        }
}

char    *envinit[3];

void
init_env(void)
{
        char **envp;

        envp = envinit;
        if ((*envp = getenv("TZ")))
                *envp++ -= 3;
        *envp = 0;
        environ = envinit;
}


/*
 * start_login(host)
 *
 * Assuming that we are now running as a child processes, this
 * function will turn us into the login process.
 */
extern char *gettyname;

void
start_login(char *host, int autologin, char *name)
{
        char **argv;
#define TABBUFSIZ       512
        char    defent[TABBUFSIZ];
        char    defstrs[TABBUFSIZ];
#undef  TABBUFSIZ
        const char *loginprog = NULL;
        extern struct sockaddr_storage from;
        char buf[sizeof(from) * 4 + 1];
        char *user;

        user = getenv("USER");
        user = (user != NULL) ? strdup(user) : NULL;

        scrub_env();

        /*
         * -a : pass on the address of the host.
         * -h : pass on name of host.
         *      WARNING:  -h and -a are accepted by login
         *      if and only if getuid() == 0.
         * -p : don't clobber the environment (so terminal type stays set).
         *
         * -f : force this login, he has already been authenticated
         */
        argv = addarg(0, "login");

        argv = addarg(argv, "-a");
        (void)strvisx(buf, (const char *)(const void *)&from, sizeof(from),
            VIS_WHITE);
        argv = addarg(argv, buf);

        argv = addarg(argv, "-h");
        argv = addarg(argv, host);

        argv = addarg(argv, "-p");
#ifdef  LINEMODE
        /*
         * Set the environment variable "LINEMODE" to either
         * "real" or "kludge" if we are operating in either
         * real or kludge linemode.
         */
        if (lmodetype == REAL_LINEMODE)
                setenv("LINEMODE", "real", 1);
# ifdef KLUDGELINEMODE
        else if (lmodetype == KLUDGE_LINEMODE || lmodetype == KLUDGE_OK)
                setenv("LINEMODE", "kludge", 1);
# endif
#endif
#ifdef SECURELOGIN
        /*
         * don't worry about the -f that might get sent.
         * A -s is supposed to override it anyhow.
         */
        if (require_secure_login)
                argv = addarg(argv, "-s");
#endif
#ifdef AUTHENTICATION
        if (auth_level >= 0 && autologin == AUTH_VALID) {
                argv = addarg(argv, "-f");
                argv = addarg(argv, "--");
                argv = addarg(argv, name);
        } else
#endif
        if (user != NULL) {
                argv = addarg(argv, "--");
                argv = addarg(argv, user);
                /*
                 * Assume that login will set the USER variable
                 * correctly.  For SysV systems, this means that
                 * USER will no longer be set, just LOGNAME by
                 * login.  (The problem is that if the auto-login
                 * fails, and the user then specifies a different
                 * account name, he can get logged in with both
                 * LOGNAME and USER in his environment, but the
                 * USER value will be wrong.
                 */
                unsetenv("USER");
        }
        if (getent(defent, gettyname) == 1) {
                char *cp = defstrs;

                loginprog = getstr("lo", &cp);
        }
        if (loginprog == NULL)
                loginprog = _PATH_LOGIN;
        closelog();
        /*
         * This sleep(1) is in here so that telnetd can
         * finish up with the tty.  There's a race condition
         * the login banner message gets lost...
         */
        sleep(1);
        execv(loginprog, argv);

        syslog(LOG_ERR, "%s: %m", loginprog);
        fatalperror(net, loginprog);
        /*NOTREACHED*/
}

char **
addarg(char **argv, const char *val)
{
        char **cpp;
        char **nargv;

        if (argv == NULL) {
                /*
                 * 10 entries, a leading length, and a null
                 */
                argv = malloc(sizeof(*argv) * 12);
                if (argv == NULL)
                        return(NULL);
                *argv++ = (char *)10;
                *argv = (char *)0;
        }
        for (cpp = argv; *cpp; cpp++)
                ;
        if (cpp == &argv[(long)argv[-1]]) {
                --argv;
                nargv = realloc(argv, sizeof(*argv) * ((long)(*argv) + 10 + 2));
                if (nargv == NULL) {
                        fatal(net, "not enough memory");
                        /*NOTREACHED*/
                }
                argv = nargv;
                *argv = (char *)((long)(*argv) + 10);
                argv++;
                cpp = &argv[(long)argv[-1] - 10];
        }
        *cpp++ = __UNCONST(val);
        *cpp = 0;
        return(argv);
}

/*
 * scrub_env()
 *
 * We only accept the environment variables listed below.
 */

void
scrub_env(void)
{
        static const char *reject[] = {
                "TERMCAP=/",
                NULL
        };

        static const char *acceptstr[] = {
                "XAUTH=", "XAUTHORITY=", "DISPLAY=",
                "TERM=",
                "EDITOR=",
                "PAGER=",
                "LOGNAME=",
                "POSIXLY_CORRECT=",
                "TERMCAP=",
                "PRINTER=",
                NULL
        };

        char **cpp, **cpp2;
        const char **p;

        for (cpp2 = cpp = environ; *cpp; cpp++) {
                int reject_it = 0;

                for(p = reject; *p; p++)
                        if(strncmp(*cpp, *p, strlen(*p)) == 0) {
                                reject_it = 1;
                                break;
                        }
                if (reject_it)
                        continue;

                for(p = acceptstr; *p; p++)
                        if(strncmp(*cpp, *p, strlen(*p)) == 0)
                                break;
                if(*p != NULL)
                        *cpp2++ = *cpp;
        }
        *cpp2 = NULL;
}

/*
 * cleanup()
 *
 * This is the routine to call when we are all through, to
 * clean up anything that needs to be cleaned up.
 */
/* ARGSUSED */
void
cleanup(int sig)
{
        char *p, c;

        p = line + sizeof(_PATH_DEV) - 1;
#ifdef SUPPORT_UTMP
        if (logout(p))
                logwtmp(p, "", "");
#endif
#ifdef SUPPORT_UTMPX
        if (logoutx(p, 0, DEAD_PROCESS))
                logwtmpx(p, "", "", 0, DEAD_PROCESS);
#endif
        (void)chmod(line, 0666);
        (void)chown(line, 0, 0);
        c = *p; *p = 'p';
        (void)chmod(line, 0666);
        (void)chown(line, 0, 0);
        *p = c;
        if (ttyaction(line, "telnetd", "root"))
                syslog(LOG_ERR, "%s: ttyaction failed", line);
        (void) shutdown(net, 2);
        exit(1);
}