priv: Introduce and use PRIV_VFS_REVOKE

[dragonfly.git] / libexec / telnetd / termstat.c

/*
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. 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.
 *
 * @(#)termstat.c       8.2 (Berkeley) 5/30/95
 * $FreeBSD: src/crypto/telnet/telnetd/termstat.c,v 1.4.2.4 2002/04/13 10:59:09 markm Exp $
 * $DragonFly: src/crypto/telnet/telnetd/termstat.c,v 1.2 2003/06/17 04:24:37 dillon Exp $
 */

#include "telnetd.h"

#ifdef  ENCRYPTION
#include <libtelnet/encrypt.h>
#endif

/*
 * local variables
 */
int def_tspeed = -1, def_rspeed = -1;
#ifdef  TIOCSWINSZ
int def_row = 0, def_col = 0;
#endif
#ifdef  LINEMODE
static int _terminit = 0;
#endif  /* LINEMODE */

#ifdef  LINEMODE
/*
 * localstat
 *
 * This function handles all management of linemode.
 *
 * Linemode allows the client to do the local editing of data
 * and send only complete lines to the server.  Linemode state is
 * based on the state of the pty driver.  If the pty is set for
 * external processing, then we can use linemode.  Further, if we
 * can use real linemode, then we can look at the edit control bits
 * in the pty to determine what editing the client should do.
 *
 * Linemode support uses the following state flags to keep track of
 * current and desired linemode state.
 *      alwayslinemode : true if -l was specified on the telnetd
 *      command line.  It means to have linemode on as much as
 *      possible.
 *
 *      lmodetype: signifies whether the client can
 *      handle real linemode, or if use of kludgeomatic linemode
 *      is preferred.  It will be set to one of the following:
 *              REAL_LINEMODE : use linemode option
 *              NO_KLUDGE : don't initiate kludge linemode.
 *              KLUDGE_LINEMODE : use kludge linemode
 *              NO_LINEMODE : client is ignorant of linemode
 *
 *      linemode, uselinemode : linemode is true if linemode
 *      is currently on, uselinemode is the state that we wish
 *      to be in.  If another function wishes to turn linemode
 *      on or off, it sets or clears uselinemode.
 *
 *      editmode, useeditmode : like linemode/uselinemode, but
 *      these contain the edit mode states (edit and trapsig).
 *
 * The state variables correspond to some of the state information
 * in the pty.
 *      linemode:
 *              In real linemode, this corresponds to whether the pty
 *              expects external processing of incoming data.
 *              In kludge linemode, this more closely corresponds to the
 *              whether normal processing is on or not.  (ICANON in
 *              system V, or COOKED mode in BSD.)
 *              If the -l option was specified (alwayslinemode), then
 *              an attempt is made to force external processing on at
 *              all times.
 *
 * The following heuristics are applied to determine linemode
 * handling within the server.
 *      1) Early on in starting up the server, an attempt is made
 *         to negotiate the linemode option.  If this succeeds
 *         then lmodetype is set to REAL_LINEMODE and all linemode
 *         processing occurs in the context of the linemode option.
 *      2) If the attempt to negotiate the linemode option failed,
 *         and the "-k" (don't initiate kludge linemode) isn't set,
 *         then we try to use kludge linemode.  We test for this
 *         capability by sending "do Timing Mark".  If a positive
 *         response comes back, then we assume that the client
 *         understands kludge linemode (ech!) and the
 *         lmodetype flag is set to KLUDGE_LINEMODE.
 *      3) Otherwise, linemode is not supported at all and
 *         lmodetype remains set to NO_LINEMODE (which happens
 *         to be 0 for convenience).
 *      4) At any time a command arrives that implies a higher
 *         state of linemode support in the client, we move to that
 *         linemode support.
 *
 * A short explanation of kludge linemode is in order here.
 *      1) The heuristic to determine support for kludge linemode
 *         is to send a do timing mark.  We assume that a client
 *         that supports timing marks also supports kludge linemode.
 *         A risky proposition at best.
 *      2) Further negotiation of linemode is done by changing the
 *         the server's state regarding SGA.  If server will SGA,
 *         then linemode is off, if server won't SGA, then linemode
 *         is on.
 */
void
localstat(void)
{
        int need_will_echo = 0;

        /*
         * Check for changes to flow control if client supports it.
         */
        flowstat();

        /*
         * Check linemode on/off state
         */
        uselinemode = tty_linemode();

        /*
         * If alwayslinemode is on, and pty is changing to turn it off, then
         * force linemode back on.
         */
        if (alwayslinemode && linemode && !uselinemode) {
                uselinemode = 1;
                tty_setlinemode(uselinemode);
        }

        if (uselinemode) {
                /*
                 * Check for state of BINARY options.
                 *
                 * We only need to do the binary dance if we are actually going
                 * to use linemode.  As this confuses some telnet clients
                 * that don't support linemode, and doesn't gain us
                 * anything, we don't do it unless we're doing linemode.
                 * -Crh (henrich@msu.edu)
                 */

                if (tty_isbinaryin()) {
                        if (his_want_state_is_wont(TELOPT_BINARY))
                                send_do(TELOPT_BINARY, 1);
                } else {
                        if (his_want_state_is_will(TELOPT_BINARY))
                                send_dont(TELOPT_BINARY, 1);
                }

                if (tty_isbinaryout()) {
                        if (my_want_state_is_wont(TELOPT_BINARY))
                                send_will(TELOPT_BINARY, 1);
                } else {
                        if (my_want_state_is_will(TELOPT_BINARY))
                                send_wont(TELOPT_BINARY, 1);
                }
        }

#ifdef  ENCRYPTION
        /*
         * If the terminal is not echoing, but editing is enabled,
         * something like password input is going to happen, so
         * if we the other side is not currently sending encrypted
         * data, ask the other side to start encrypting.
         */
        if (his_state_is_will(TELOPT_ENCRYPT)) {
                static int enc_passwd = 0;
                if (uselinemode && !tty_isecho() && tty_isediting()
                    && (enc_passwd == 0) && !decrypt_input) {
                        encrypt_send_request_start();
                        enc_passwd = 1;
                } else if (enc_passwd) {
                        encrypt_send_request_end();
                        enc_passwd = 0;
                }
        }
#endif  /* ENCRYPTION */

        /*
         * Do echo mode handling as soon as we know what the
         * linemode is going to be.
         * If the pty has echo turned off, then tell the client that
         * the server will echo.  If echo is on, then the server
         * will echo if in character mode, but in linemode the
         * client should do local echoing.  The state machine will
         * not send anything if it is unnecessary, so don't worry
         * about that here.
         *
         * If we need to send the WILL ECHO (because echo is off),
         * then delay that until after we have changed the MODE.
         * This way, when the user is turning off both editing
         * and echo, the client will get editing turned off first.
         * This keeps the client from going into encryption mode
         * and then right back out if it is doing auto-encryption
         * when passwords are being typed.
         */
        if (uselinemode) {
                if (tty_isecho())
                        send_wont(TELOPT_ECHO, 1);
                else
                        need_will_echo = 1;
#ifdef  KLUDGELINEMODE
                if (lmodetype == KLUDGE_OK)
                        lmodetype = KLUDGE_LINEMODE;
#endif
        }

        /*
         * If linemode is being turned off, send appropriate
         * command and then we're all done.
         */
         if (!uselinemode && linemode) {
# ifdef KLUDGELINEMODE
                if (lmodetype == REAL_LINEMODE) {
# endif /* KLUDGELINEMODE */
                        send_dont(TELOPT_LINEMODE, 1);
# ifdef KLUDGELINEMODE
                } else if (lmodetype == KLUDGE_LINEMODE)
                        send_will(TELOPT_SGA, 1);
# endif /* KLUDGELINEMODE */
                send_will(TELOPT_ECHO, 1);
                linemode = uselinemode;
                goto done;
        }

# ifdef KLUDGELINEMODE
        /*
         * If using real linemode check edit modes for possible later use.
         * If we are in kludge linemode, do the SGA negotiation.
         */
        if (lmodetype == REAL_LINEMODE) {
# endif /* KLUDGELINEMODE */
                useeditmode = 0;
                if (tty_isediting())
                        useeditmode |= MODE_EDIT;
                if (tty_istrapsig())
                        useeditmode |= MODE_TRAPSIG;
                if (tty_issofttab())
                        useeditmode |= MODE_SOFT_TAB;
                if (tty_islitecho())
                        useeditmode |= MODE_LIT_ECHO;
# ifdef KLUDGELINEMODE
        } else if (lmodetype == KLUDGE_LINEMODE) {
                if (tty_isediting() && uselinemode)
                        send_wont(TELOPT_SGA, 1);
                else
                        send_will(TELOPT_SGA, 1);
        }
# endif /* KLUDGELINEMODE */

        /*
         * Negotiate linemode on if pty state has changed to turn it on.
         * Send appropriate command and send along edit mode, then all done.
         */
        if (uselinemode && !linemode) {
# ifdef KLUDGELINEMODE
                if (lmodetype == KLUDGE_LINEMODE) {
                        send_wont(TELOPT_SGA, 1);
                } else if (lmodetype == REAL_LINEMODE) {
# endif /* KLUDGELINEMODE */
                        send_do(TELOPT_LINEMODE, 1);
                        /* send along edit modes */
                        output_data("%c%c%c%c%c%c%c", IAC, SB,
                                TELOPT_LINEMODE, LM_MODE, useeditmode,
                                IAC, SE);
                        editmode = useeditmode;
# ifdef KLUDGELINEMODE
                }
# endif /* KLUDGELINEMODE */
                linemode = uselinemode;
                goto done;
        }

# ifdef KLUDGELINEMODE
        /*
         * None of what follows is of any value if not using
         * real linemode.
         */
        if (lmodetype < REAL_LINEMODE)
                goto done;
# endif /* KLUDGELINEMODE */

        if (linemode && his_state_is_will(TELOPT_LINEMODE)) {
                /*
                 * If edit mode changed, send edit mode.
                 */
                 if (useeditmode != editmode) {
                        /*
                         * Send along appropriate edit mode mask.
                         */
                        output_data("%c%c%c%c%c%c%c", IAC, SB,
                                TELOPT_LINEMODE, LM_MODE, useeditmode,
                                IAC, SE);
                        editmode = useeditmode;
                }


                /*
                 * Check for changes to special characters in use.
                 */
                start_slc(0);
                check_slc();
                (void) end_slc(0);
        }

done:
        if (need_will_echo)
                send_will(TELOPT_ECHO, 1);
        /*
         * Some things should be deferred until after the pty state has
         * been set by the local process.  Do those things that have been
         * deferred now.  This only happens once.
         */
        if (_terminit == 0) {
                _terminit = 1;
                defer_terminit();
        }

        netflush();
        set_termbuf();
        return;

}  /* end of localstat */
#endif  /* LINEMODE */

/*
 * flowstat
 *
 * Check for changes to flow control
 */
void
flowstat(void)
{
        if (his_state_is_will(TELOPT_LFLOW)) {
                if (tty_flowmode() != flowmode) {
                        flowmode = tty_flowmode();
                        output_data("%c%c%c%c%c%c",
                                        IAC, SB, TELOPT_LFLOW,
                                        flowmode ? LFLOW_ON : LFLOW_OFF,
                                        IAC, SE);
                }
                if (tty_restartany() != restartany) {
                        restartany = tty_restartany();
                        output_data("%c%c%c%c%c%c",
                                        IAC, SB, TELOPT_LFLOW,
                                        restartany ? LFLOW_RESTART_ANY
                                                   : LFLOW_RESTART_XON,
                                        IAC, SE);
                }
        }
}

/*
 * clientstat
 *
 * Process linemode related requests from the client.
 * Client can request a change to only one of linemode, editmode or slc's
 * at a time, and if using kludge linemode, then only linemode may be
 * affected.
 */
void
clientstat(int code, int parm1, int parm2)
{

        /*
         * Get a copy of terminal characteristics.
         */
        init_termbuf();

        /*
         * Process request from client. code tells what it is.
         */
        switch (code) {
#ifdef  LINEMODE
        case TELOPT_LINEMODE:
                /*
                 * Don't do anything unless client is asking us to change
                 * modes.
                 */
                uselinemode = (parm1 == WILL);
                if (uselinemode != linemode) {
# ifdef KLUDGELINEMODE
                        /*
                         * If using kludge linemode, make sure that
                         * we can do what the client asks.
                         * We can not turn off linemode if alwayslinemode
                         * and the ICANON bit is set.
                         */
                        if (lmodetype == KLUDGE_LINEMODE) {
                                if (alwayslinemode && tty_isediting()) {
                                        uselinemode = 1;
                                }
                        }

                        /*
                         * Quit now if we can't do it.
                         */
                        if (uselinemode == linemode)
                                return;

                        /*
                         * If using real linemode and linemode is being
                         * turned on, send along the edit mode mask.
                         */
                        if (lmodetype == REAL_LINEMODE && uselinemode)
# else  /* KLUDGELINEMODE */
                        if (uselinemode)
# endif /* KLUDGELINEMODE */
                        {
                                useeditmode = 0;
                                if (tty_isediting())
                                        useeditmode |= MODE_EDIT;
                                if (tty_istrapsig)
                                        useeditmode |= MODE_TRAPSIG;
                                if (tty_issofttab())
                                        useeditmode |= MODE_SOFT_TAB;
                                if (tty_islitecho())
                                        useeditmode |= MODE_LIT_ECHO;
                                output_data("%c%c%c%c%c%c%c", IAC,
                                        SB, TELOPT_LINEMODE, LM_MODE,
                                                        useeditmode, IAC, SE);
                                editmode = useeditmode;
                        }


                        tty_setlinemode(uselinemode);

                        linemode = uselinemode;

                        if (!linemode)
                                send_will(TELOPT_ECHO, 1);
                }
                break;

        case LM_MODE:
            {
                int ack, changed;

                /*
                 * Client has sent along a mode mask.  If it agrees with
                 * what we are currently doing, ignore it; if not, it could
                 * be viewed as a request to change.  Note that the server
                 * will change to the modes in an ack if it is different from
                 * what we currently have, but we will not ack the ack.
                 */
                 useeditmode &= MODE_MASK;
                 ack = (useeditmode & MODE_ACK);
                 useeditmode &= ~MODE_ACK;

                 if ((changed = (useeditmode ^ editmode))) {
                        /*
                         * This check is for a timing problem.  If the
                         * state of the tty has changed (due to the user
                         * application) we need to process that info
                         * before we write in the state contained in the
                         * ack!!!  This gets out the new MODE request,
                         * and when the ack to that command comes back
                         * we'll set it and be in the right mode.
                         */
                        if (ack)
                                localstat();
                        if (changed & MODE_EDIT)
                                tty_setedit(useeditmode & MODE_EDIT);

                        if (changed & MODE_TRAPSIG)
                                tty_setsig(useeditmode & MODE_TRAPSIG);

                        if (changed & MODE_SOFT_TAB)
                                tty_setsofttab(useeditmode & MODE_SOFT_TAB);

                        if (changed & MODE_LIT_ECHO)
                                tty_setlitecho(useeditmode & MODE_LIT_ECHO);

                        set_termbuf();

                        if (!ack) {
                                output_data("%c%c%c%c%c%c%c", IAC,
                                        SB, TELOPT_LINEMODE, LM_MODE,
                                        useeditmode|MODE_ACK,
                                        IAC, SE);
                        }

                        editmode = useeditmode;
                }

                break;

            }  /* end of case LM_MODE */
#endif  /* LINEMODE */

        case TELOPT_NAWS:
#ifdef  TIOCSWINSZ
            {
                struct winsize ws;

                def_col = parm1;
                def_row = parm2;
#ifdef  LINEMODE
                /*
                 * Defer changing window size until after terminal is
                 * initialized.
                 */
                if (terminit() == 0)
                        return;
#endif  /* LINEMODE */

                /*
                 * Change window size as requested by client.
                 */

                ws.ws_col = parm1;
                ws.ws_row = parm2;
                (void) ioctl(pty, TIOCSWINSZ, (char *)&ws);
            }
#endif  /* TIOCSWINSZ */

                break;

        case TELOPT_TSPEED:
            {
                def_tspeed = parm1;
                def_rspeed = parm2;
#ifdef  LINEMODE
                /*
                 * Defer changing the terminal speed.
                 */
                if (terminit() == 0)
                        return;
#endif  /* LINEMODE */
                /*
                 * Change terminal speed as requested by client.
                 * We set the receive speed first, so that if we can't
                 * store separate receive and transmit speeds, the transmit
                 * speed will take precedence.
                 */
                tty_rspeed(parm2);
                tty_tspeed(parm1);
                set_termbuf();

                break;

            }  /* end of case TELOPT_TSPEED */

        default:
                /* What? */
                break;
        }  /* end of switch */

        netflush();

}  /* end of clientstat */

#ifdef  LINEMODE
/*
 * defer_terminit
 *
 * Some things should not be done until after the login process has started
 * and all the pty modes are set to what they are supposed to be.  This
 * function is called when the pty state has been processed for the first time.
 * It calls other functions that do things that were deferred in each module.
 */
void
defer_terminit(void)
{

        /*
         * local stuff that got deferred.
         */
        if (def_tspeed != -1) {
                clientstat(TELOPT_TSPEED, def_tspeed, def_rspeed);
                def_tspeed = def_rspeed = 0;
        }

#ifdef  TIOCSWINSZ
        if (def_col || def_row) {
                struct winsize ws;

                memset((char *)&ws, 0, sizeof(ws));
                ws.ws_col = def_col;
                ws.ws_row = def_row;
                (void) ioctl(pty, TIOCSWINSZ, (char *)&ws);
        }
#endif

        /*
         * The only other module that currently defers anything.
         */
        deferslc();

}  /* end of defer_terminit */

/*
 * terminit
 *
 * Returns true if the pty state has been processed yet.
 */
int
terminit(void)
{
        return(_terminit);

}  /* end of terminit */
#endif  /* LINEMODE */