/*
 * Copyright (c) 1988, 1990, 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.
 */

#if 0
#ifndef lint
static const char sccsid[] = "@(#)telnet.c      8.4 (Berkeley) 5/30/95";
#endif
#endif
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include <sys/types.h>

/* By the way, we need to include curses.h before telnet.h since,
 * among other things, telnet.h #defines 'DO', which is a variable
 * declared in curses.h.
 */

#include <ctype.h>
#include <curses.h>
#include <signal.h>
#include <stdlib.h>
#include <term.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <arpa/telnet.h>

#include "ring.h"

#include "defines.h"
#include "externs.h"
#include "types.h"
#include "general.h"

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

#define strip(x) ((my_want_state_is_wont(TELOPT_BINARY)) ? ((x)&0x7f) : (x))

static unsigned char    subbuffer[SUBBUFSIZE],
                        *subpointer, *subend;    /* buffer for sub-options */
#define SB_CLEAR()      subpointer = subbuffer;
#define SB_TERM()       { subend = subpointer; SB_CLEAR(); }
#define SB_ACCUM(c)     if (subpointer < (subbuffer+sizeof subbuffer)) { \
                                *subpointer++ = (c); \
                        }

#define SB_GET()        ((*subpointer++)&0xff)
#define SB_PEEK()       ((*subpointer)&0xff)
#define SB_EOF()        (subpointer >= subend)
#define SB_LEN()        (subend - subpointer)

char    options[256];           /* The combined options */
char    do_dont_resp[256];
char    will_wont_resp[256];

int
        eight = 0,
        autologin = 0,  /* Autologin anyone? */
        skiprc = 0,
        connected,
        showoptions,
        ISend,          /* trying to send network data in */
        telnet_debug = 0,
        crmod,
        netdata,        /* Print out network data flow */
        crlf,           /* Should '\r' be mapped to <CR><LF> (or <CR><NUL>)? */
        telnetport,
        SYNCHing,       /* we are in TELNET SYNCH mode */
        flushout,       /* flush output */
        autoflush = 0,  /* flush output when interrupting? */
        autosynch,      /* send interrupt characters with SYNCH? */
        localflow,      /* we handle flow control locally */
        restartany,     /* if flow control enabled, restart on any character */
        localchars,     /* we recognize interrupt/quit */
        donelclchars,   /* the user has set "localchars" */
        donebinarytoggle,       /* the user has put us in binary */
        dontlecho,      /* do we suppress local echoing right now? */
        globalmode,
        doaddrlookup = 1, /* do a reverse address lookup? */
        clienteof = 0;

char *prompt = 0;
#ifdef ENCRYPTION
char *line;             /* hack around breakage in sra.c :-( !! */
#endif

cc_t escape;
cc_t rlogin;
#ifdef  KLUDGELINEMODE
cc_t echoc;
#endif

/*
 * Telnet receiver states for fsm
 */
#define TS_DATA         0
#define TS_IAC          1
#define TS_WILL         2
#define TS_WONT         3
#define TS_DO           4
#define TS_DONT         5
#define TS_CR           6
#define TS_SB           7               /* sub-option collection */
#define TS_SE           8               /* looking for sub-option end */

static int      telrcv_state;
#ifdef  OLD_ENVIRON
unsigned char telopt_environ = TELOPT_NEW_ENVIRON;
#else
# define telopt_environ TELOPT_NEW_ENVIRON
#endif

jmp_buf toplevel;

int     flushline;
int     linemode;

#ifdef  KLUDGELINEMODE
int     kludgelinemode = 1;
#endif

static int is_unique(char *, char **, char **);

/*
 * The following are some clocks used to decide how to interpret
 * the relationship between various variables.
 */

Clocks clocks;

/*
 * Initialize telnet environment.
 */

void
init_telnet(void)
{
    env_init();

    SB_CLEAR();
    ClearArray(options);

    connected = ISend = localflow = donebinarytoggle = 0;
#ifdef  AUTHENTICATION
#ifdef  ENCRYPTION
    auth_encrypt_connect(connected);
#endif
#endif
    restartany = -1;

    SYNCHing = 0;

    /* Don't change NetTrace */

    escape = CONTROL(']');
    rlogin = _POSIX_VDISABLE;
#ifdef  KLUDGELINEMODE
    echoc = CONTROL('E');
#endif

    flushline = 1;
    telrcv_state = TS_DATA;
}


/*
 * These routines are in charge of sending option negotiations
 * to the other side.
 *
 * The basic idea is that we send the negotiation if either side
 * is in disagreement as to what the current state should be.
 */

unsigned char ComPortBaudRate[256];

void
DoBaudRate(char *arg)
{
    char *temp, temp2[11];
    int i;
    uint32_t baudrate;

    errno = 0;
    baudrate = (uint32_t)strtol(arg, &temp, 10);
    if (temp[0] != '\0' || (baudrate == 0 && errno != 0))
        ExitString("Invalid baud rate provided.\n", 1);

    for (i = 1; termspeeds[i].speed != -1; i++)
        if (baudrate == termspeeds[i].speed)
            break;
    if (termspeeds[i].speed == -1)
        ExitString("Invalid baud rate provided.\n", 1);

    strlcpy(ComPortBaudRate, arg, sizeof(ComPortBaudRate));

    if (NETROOM() < sizeof(temp2)) {
        ExitString("No room in buffer for baud rate.\n", 1);
        /* NOTREACHED */
    }

    snprintf(temp2, sizeof(temp2), "%c%c%c%c....%c%c", IAC, SB, TELOPT_COMPORT,
        COMPORT_SET_BAUDRATE, IAC, SE);

    baudrate = htonl(baudrate);
    memcpy(&temp2[4], &baudrate, sizeof(baudrate));
    ring_supply_data(&netoring, temp2, sizeof(temp2));
    printsub('>', &temp[2], sizeof(temp2) - 2);
}

void
send_do(int c, int init)
{
    if (init) {
        if (((do_dont_resp[c] == 0) && my_state_is_do(c)) ||
                                my_want_state_is_do(c))
            return;
        set_my_want_state_do(c);
        do_dont_resp[c]++;
    }
    if (telnetport < 0)
        return;
    NET2ADD(IAC, DO);
    NETADD(c);
    printoption("SENT", DO, c);
}

void
send_dont(int c, int init)
{
    if (init) {
        if (((do_dont_resp[c] == 0) && my_state_is_dont(c)) ||
                                my_want_state_is_dont(c))
            return;
        set_my_want_state_dont(c);
        do_dont_resp[c]++;
    }
    if (telnetport < 0)
        return;
    NET2ADD(IAC, DONT);
    NETADD(c);
    printoption("SENT", DONT, c);
}

void
send_will(int c, int init)
{
    if (init) {
        if (((will_wont_resp[c] == 0) && my_state_is_will(c)) ||
                                my_want_state_is_will(c))
            return;
        set_my_want_state_will(c);
        will_wont_resp[c]++;
    }
    if (telnetport < 0)
        return;
    NET2ADD(IAC, WILL);
    NETADD(c);
    printoption("SENT", WILL, c);
}

void
send_wont(int c, int init)
{
    if (init) {
        if (((will_wont_resp[c] == 0) && my_state_is_wont(c)) ||
                                my_want_state_is_wont(c))
            return;
        set_my_want_state_wont(c);
        will_wont_resp[c]++;
    }
    if (telnetport < 0)
        return;
    NET2ADD(IAC, WONT);
    NETADD(c);
    printoption("SENT", WONT, c);
}

void
willoption(int option)
{
        int new_state_ok = 0;

        if (do_dont_resp[option]) {
            --do_dont_resp[option];
            if (do_dont_resp[option] && my_state_is_do(option))
                --do_dont_resp[option];
        }

        if ((do_dont_resp[option] == 0) && my_want_state_is_dont(option)) {

            switch (option) {

            case TELOPT_ECHO:
            case TELOPT_BINARY:
            case TELOPT_SGA:
                settimer(modenegotiated);
                /* FALLTHROUGH */
            case TELOPT_STATUS:
#ifdef  AUTHENTICATION
            case TELOPT_AUTHENTICATION:
#endif
#ifdef  ENCRYPTION
            case TELOPT_ENCRYPT:
#endif /* ENCRYPTION */
                new_state_ok = 1;
                break;

            case TELOPT_TM:
                if (flushout)
                    flushout = 0;
                /*
                 * Special case for TM.  If we get back a WILL,
                 * pretend we got back a WONT.
                 */
                set_my_want_state_dont(option);
                set_my_state_dont(option);
                return;                 /* Never reply to TM will's/wont's */

            case TELOPT_LINEMODE:
            default:
                break;
            }

            if (new_state_ok) {
                set_my_want_state_do(option);
                send_do(option, 0);
                setconnmode(0);         /* possibly set new tty mode */
            } else {
                do_dont_resp[option]++;
                send_dont(option, 0);
            }
        }
        set_my_state_do(option);
#ifdef  ENCRYPTION
        if (option == TELOPT_ENCRYPT)
                encrypt_send_support();
#endif  /* ENCRYPTION */
}

void
wontoption(int option)
{
        if (do_dont_resp[option]) {
            --do_dont_resp[option];
            if (do_dont_resp[option] && my_state_is_dont(option))
                --do_dont_resp[option];
        }

        if ((do_dont_resp[option] == 0) && my_want_state_is_do(option)) {

            switch (option) {

#ifdef  KLUDGELINEMODE
            case TELOPT_SGA:
                if (!kludgelinemode)
                    break;
                /* FALLTHROUGH */
#endif
            case TELOPT_ECHO:
                settimer(modenegotiated);
                break;

            case TELOPT_TM:
                if (flushout)
                    flushout = 0;
                set_my_want_state_dont(option);
                set_my_state_dont(option);
                return;         /* Never reply to TM will's/wont's */

            default:
                break;
            }
            set_my_want_state_dont(option);
            if (my_state_is_do(option))
                send_dont(option, 0);
            setconnmode(0);                     /* Set new tty mode */
        } else if (option == TELOPT_TM) {
            /*
             * Special case for TM.
             */
            if (flushout)
                flushout = 0;
            set_my_want_state_dont(option);
        }
        set_my_state_dont(option);
}

static void
dooption(int option)
{
        int new_state_ok = 0;

        if (will_wont_resp[option]) {
            --will_wont_resp[option];
            if (will_wont_resp[option] && my_state_is_will(option))
                --will_wont_resp[option];
        }

        if (will_wont_resp[option] == 0) {
          if (my_want_state_is_wont(option)) {

            switch (option) {

            case TELOPT_TM:
                /*
                 * Special case for TM.  We send a WILL, but pretend
                 * we sent WONT.
                 */
                send_will(option, 0);
                set_my_want_state_wont(TELOPT_TM);
                set_my_state_wont(TELOPT_TM);
                return;

            case TELOPT_BINARY:         /* binary mode */
            case TELOPT_NAWS:           /* window size */
            case TELOPT_TSPEED:         /* terminal speed */
            case TELOPT_LFLOW:          /* local flow control */
            case TELOPT_TTYPE:          /* terminal type option */
            case TELOPT_SGA:            /* no big deal */
#ifdef  ENCRYPTION
            case TELOPT_ENCRYPT:        /* encryption variable option */
#endif  /* ENCRYPTION */
                new_state_ok = 1;
                break;

            case TELOPT_NEW_ENVIRON:    /* New environment variable option */
#ifdef  OLD_ENVIRON
                if (my_state_is_will(TELOPT_OLD_ENVIRON))
                        send_wont(TELOPT_OLD_ENVIRON, 1); /* turn off the old */
                goto env_common;
            case TELOPT_OLD_ENVIRON:    /* Old environment variable option */
                if (my_state_is_will(TELOPT_NEW_ENVIRON))
                        break;          /* Don't enable if new one is in use! */
            env_common:
                telopt_environ = option;
#endif
                new_state_ok = 1;
                break;

#ifdef  AUTHENTICATION
            case TELOPT_AUTHENTICATION:
                if (autologin)
                        new_state_ok = 1;
                break;
#endif

            case TELOPT_XDISPLOC:       /* X Display location */
                if (env_getvalue("DISPLAY"))
                    new_state_ok = 1;
                break;

            case TELOPT_LINEMODE:
#ifdef  KLUDGELINEMODE
                kludgelinemode = 0;
                send_do(TELOPT_SGA, 1);
#endif
                set_my_want_state_will(TELOPT_LINEMODE);
                send_will(option, 0);
                set_my_state_will(TELOPT_LINEMODE);
                slc_init();
                return;

            case TELOPT_ECHO:           /* We're never going to echo... */
            default:
                break;
            }

            if (new_state_ok) {
                set_my_want_state_will(option);
                send_will(option, 0);
                setconnmode(0);                 /* Set new tty mode */
            } else {
                will_wont_resp[option]++;
                send_wont(option, 0);
            }
          } else {
            /*
             * Handle options that need more things done after the
             * other side has acknowledged the option.
             */
            switch (option) {
            case TELOPT_LINEMODE:
#ifdef  KLUDGELINEMODE
                kludgelinemode = 0;
                send_do(TELOPT_SGA, 1);
#endif
                set_my_state_will(option);
                slc_init();
                send_do(TELOPT_SGA, 0);
                return;
            }
          }
        }
        set_my_state_will(option);
}

static void
dontoption(int option)
{

        if (will_wont_resp[option]) {
            --will_wont_resp[option];
            if (will_wont_resp[option] && my_state_is_wont(option))
                --will_wont_resp[option];
        }

        if ((will_wont_resp[option] == 0) && my_want_state_is_will(option)) {
            switch (option) {
            case TELOPT_LINEMODE:
                linemode = 0;   /* put us back to the default state */
                break;
#ifdef  OLD_ENVIRON
            case TELOPT_NEW_ENVIRON:
                /*
                 * The new environ option wasn't recognized, try
                 * the old one.
                 */
                send_will(TELOPT_OLD_ENVIRON, 1);
                telopt_environ = TELOPT_OLD_ENVIRON;
                break;
#endif
            }
            /* we always accept a DONT */
            set_my_want_state_wont(option);
            if (my_state_is_will(option))
                send_wont(option, 0);
            setconnmode(0);                     /* Set new tty mode */
        }
        set_my_state_wont(option);
}

/*
 * Given a buffer returned by tgetent(), this routine will turn
 * the pipe separated list of names in the buffer into an array
 * of pointers to null terminated names.  We toss out any bad,
 * duplicate, or verbose names (names with spaces).
 */

static const char *name_unknown = "UNKNOWN";
static const char *unknown[] = { NULL, NULL };

static const char **
mklist(char *buf, char *name)
{
        int n;
        char c, *cp, **argvp, *cp2, **argv, **avt;

        if (name) {
                if (strlen(name) > 40) {
                        name = 0;
                        unknown[0] = name_unknown;
                } else {
                        unknown[0] = name;
                        upcase(name);
                }
        } else
                unknown[0] = name_unknown;
        /*
         * Count up the number of names.
         */
        for (n = 1, cp = buf; *cp && *cp != ':'; cp++) {
                if (*cp == '|')
                        n++;
        }
        /*
         * Allocate an array to put the name pointers into
         */
        argv = (char **)malloc((n+3)*sizeof(char *));
        if (argv == 0)
                return(unknown);

        /*
         * Fill up the array of pointers to names.
         */
        *argv = 0;
        argvp = argv+1;
        n = 0;
        for (cp = cp2 = buf; (c = *cp);  cp++) {
                if (c == '|' || c == ':') {
                        *cp++ = '\0';
                        /*
                         * Skip entries that have spaces or are over 40
                         * characters long.  If this is our environment
                         * name, then put it up front.  Otherwise, as
                         * long as this is not a duplicate name (case
                         * insensitive) add it to the list.
                         */
                        if (n || (cp - cp2 > 41))
                                ;
                        else if (name && (strncasecmp(name, cp2, cp-cp2) == 0))
                                *argv = cp2;
                        else if (is_unique(cp2, argv+1, argvp))
                                *argvp++ = cp2;
                        if (c == ':')
                                break;
                        /*
                         * Skip multiple delimiters. Reset cp2 to
                         * the beginning of the next name. Reset n,
                         * the flag for names with spaces.
                         */
                        while ((c = *cp) == '|')
                                cp++;
                        cp2 = cp;
                        n = 0;
                }
                /*
                 * Skip entries with spaces or non-ascii values.
                 * Convert lower case letters to upper case.
                 */
                if ((c == ' ') || !isascii(c))
                        n = 1;
                else if (islower(c))
                        *cp = toupper(c);
        }

        /*
         * Check for an old V6 2 character name.  If the second
         * name points to the beginning of the buffer, and is
         * only 2 characters long, move it to the end of the array.
         */
        if ((argv[1] == buf) && (strlen(argv[1]) == 2)) {
                --argvp;
                for (avt = &argv[1]; avt < argvp; avt++)
                        *avt = *(avt+1);
                *argvp++ = buf;
        }

        /*
         * Duplicate last name, for TTYPE option, and null
         * terminate the array.  If we didn't find a match on
         * our terminal name, put that name at the beginning.
         */
        cp = *(argvp-1);
        *argvp++ = cp;
        *argvp = 0;

        if (*argv == 0) {
                if (name)
                        *argv = name;
                else {
                        --argvp;
                        for (avt = argv; avt < argvp; avt++)
                                *avt = *(avt+1);
                }
        }
        if (*argv)
                return((const char **)argv);
        else
                return(unknown);
}

static int
is_unique(char *name, char **as, char **ae)
{
        char **ap;
        int n;

        n = strlen(name) + 1;
        for (ap = as; ap < ae; ap++)
                if (strncasecmp(*ap, name, n) == 0)
                        return(0);
        return (1);
}

#ifdef  TERMCAP
char termbuf[1024];

/*ARGSUSED*/
static int
setupterm(char *tname, int fd, int *errp)
{
        if (tgetent(termbuf, tname) == 1) {
                termbuf[1023] = '\0';
                if (errp)
                        *errp = 1;
                return(0);
        }
        if (errp)
                *errp = 0;
        return(-1);
}
#else
#define termbuf ttytype
extern char ttytype[];
#endif

int resettermname = 1;

static const char *
gettermname(void)
{
        char *tname;
        static const char **tnamep = 0;
        static const char **next;
        int err;

        if (resettermname) {
                resettermname = 0;
                if (tnamep && tnamep != unknown)
                        free(tnamep);
                if ((tname = env_getvalue("TERM")) &&
                                (setupterm(tname, 1, &err) == 0)) {
                        tnamep = mklist(termbuf, tname);
                } else {
                        if (tname && (strlen(tname) <= 40)) {
                                unknown[0] = tname;
                                upcase(tname);
                        } else
                                unknown[0] = name_unknown;
                        tnamep = unknown;
                }
                next = tnamep;
        }
        if (*next == 0)
                next = tnamep;
        return(*next++);
}
/*
 * suboption()
 *
 *      Look at the sub-option buffer, and try to be helpful to the other
 * side.
 *
 *      Currently we recognize:
 *
 *              Terminal type, send request.
 *              Terminal speed (send request).
 *              Local flow control (is request).
 *              Linemode
 */

static void
suboption(void)
{
    unsigned char subchar;

    printsub('<', subbuffer, SB_LEN()+2);
    switch (subchar = SB_GET()) {
    case TELOPT_TTYPE:
        if (my_want_state_is_wont(TELOPT_TTYPE))
            return;
        if (SB_EOF() || SB_GET() != TELQUAL_SEND) {
            return;
        } else {
            const char *name;
            unsigned char temp[50];
            int len;

            name = gettermname();
            len = strlen(name) + 4 + 2;
            if (len < NETROOM()) {
                snprintf(temp, sizeof(temp), "%c%c%c%c%s%c%c", IAC, SB, TELOPT_TTYPE,
                                TELQUAL_IS, name, IAC, SE);
                ring_supply_data(&netoring, temp, len);
                printsub('>', &temp[2], len-2);
            } else {
                ExitString("No room in buffer for terminal type.\n", 1);
                /*NOTREACHED*/
            }
        }
        break;
    case TELOPT_TSPEED:
        if (my_want_state_is_wont(TELOPT_TSPEED))
            return;
        if (SB_EOF())
            return;
        if (SB_GET() == TELQUAL_SEND) {
            long ospeed, ispeed;
            unsigned char temp[50];
            int len;

            TerminalSpeeds(&ispeed, &ospeed);

            snprintf((char *)temp, sizeof(temp), "%c%c%c%c%ld,%ld%c%c", IAC, SB, TELOPT_TSPEED,
                    TELQUAL_IS, ospeed, ispeed, IAC, SE);
            len = strlen((char *)temp+4) + 4;   /* temp[3] is 0 ... */

            if (len < NETROOM()) {
                ring_supply_data(&netoring, temp, len);
                printsub('>', temp+2, len - 2);
            }
/*@*/       else printf("lm_will: not enough room in buffer\n");
        }
        break;
    case TELOPT_LFLOW:
        if (my_want_state_is_wont(TELOPT_LFLOW))
            return;
        if (SB_EOF())
            return;
        switch(SB_GET()) {
        case LFLOW_RESTART_ANY:
            restartany = 1;
            break;
        case LFLOW_RESTART_XON:
            restartany = 0;
            break;
        case LFLOW_ON:
            localflow = 1;
            break;
        case LFLOW_OFF:
            localflow = 0;
            break;
        default:
            return;
        }
        setcommandmode();
        setconnmode(0);
        break;

    case TELOPT_LINEMODE:
        if (my_want_state_is_wont(TELOPT_LINEMODE))
            return;
        if (SB_EOF())
            return;
        switch (SB_GET()) {
        case WILL:
            lm_will(subpointer, SB_LEN());
            break;
        case WONT:
            lm_wont(subpointer, SB_LEN());
            break;
        case DO:
            lm_do(subpointer, SB_LEN());
            break;
        case DONT:
            lm_dont(subpointer, SB_LEN());
            break;
        case LM_SLC:
            slc(subpointer, SB_LEN());
            break;
        case LM_MODE:
            lm_mode(subpointer, SB_LEN(), 0);
            break;
        default:
            break;
        }
        break;

#ifdef  OLD_ENVIRON
    case TELOPT_OLD_ENVIRON:
#endif
    case TELOPT_NEW_ENVIRON:
        if (SB_EOF())
            return;
        switch(SB_PEEK()) {
        case TELQUAL_IS:
        case TELQUAL_INFO:
            if (my_want_state_is_dont(subchar))
                return;
            break;
        case TELQUAL_SEND:
            if (my_want_state_is_wont(subchar)) {
                return;
            }
            break;
        default:
            return;
        }
        env_opt(subpointer, SB_LEN());
        break;

    case TELOPT_XDISPLOC:
        if (my_want_state_is_wont(TELOPT_XDISPLOC))
            return;
        if (SB_EOF())
            return;
        if (SB_GET() == TELQUAL_SEND) {
            unsigned char temp[50], *dp;
            int len;

            if ((dp = env_getvalue("DISPLAY")) == NULL ||
                strlen(dp) > sizeof(temp) - 7) {
                /*
                 * Something happened, we no longer have a DISPLAY
                 * variable.  Or it is too long.  So, turn off the option.
                 */
                send_wont(TELOPT_XDISPLOC, 1);
                break;
            }
            snprintf(temp, sizeof(temp), "%c%c%c%c%s%c%c", IAC, SB,
                    TELOPT_XDISPLOC, TELQUAL_IS, dp, IAC, SE);
            len = strlen((char *)temp+4) + 4;   /* temp[3] is 0 ... */

            if (len < NETROOM()) {
                ring_supply_data(&netoring, temp, len);
                printsub('>', temp+2, len - 2);
            }
/*@*/       else printf("lm_will: not enough room in buffer\n");
        }
        break;

#ifdef  AUTHENTICATION
        case TELOPT_AUTHENTICATION: {
                if (!autologin)
                        break;
                if (SB_EOF())
                        return;
                switch(SB_GET()) {
                case TELQUAL_IS:
                        if (my_want_state_is_dont(TELOPT_AUTHENTICATION))
                                return;
                        auth_is(subpointer, SB_LEN());
                        break;
                case TELQUAL_SEND:
                        if (my_want_state_is_wont(TELOPT_AUTHENTICATION))
                                return;
                        auth_send(subpointer, SB_LEN());
                        break;
                case TELQUAL_REPLY:
                        if (my_want_state_is_wont(TELOPT_AUTHENTICATION))
                                return;
                        auth_reply(subpointer, SB_LEN());
                        break;
                case TELQUAL_NAME:
                        if (my_want_state_is_dont(TELOPT_AUTHENTICATION))
                                return;
                        auth_name(subpointer, SB_LEN());
                        break;
                }
        }
        break;
#endif
#ifdef  ENCRYPTION
        case TELOPT_ENCRYPT:
                if (SB_EOF())
                        return;
                switch(SB_GET()) {
                case ENCRYPT_START:
                        if (my_want_state_is_dont(TELOPT_ENCRYPT))
                                return;
                        encrypt_start(subpointer, SB_LEN());
                        break;
                case ENCRYPT_END:
                        if (my_want_state_is_dont(TELOPT_ENCRYPT))
                                return;
                        encrypt_end();
                        break;
                case ENCRYPT_SUPPORT:
                        if (my_want_state_is_wont(TELOPT_ENCRYPT))
                                return;
                        encrypt_support(subpointer, SB_LEN());
                        break;
                case ENCRYPT_REQSTART:
                        if (my_want_state_is_wont(TELOPT_ENCRYPT))
                                return;
                        encrypt_request_start(subpointer, SB_LEN());
                        break;
                case ENCRYPT_REQEND:
                        if (my_want_state_is_wont(TELOPT_ENCRYPT))
                                return;
                        /*
                         * We can always send an REQEND so that we cannot
                         * get stuck encrypting.  We should only get this
                         * if we have been able to get in the correct mode
                         * anyhow.
                         */
                        encrypt_request_end();
                        break;
                case ENCRYPT_IS:
                        if (my_want_state_is_dont(TELOPT_ENCRYPT))
                                return;
                        encrypt_is(subpointer, SB_LEN());
                        break;
                case ENCRYPT_REPLY:
                        if (my_want_state_is_wont(TELOPT_ENCRYPT))
                                return;
                        encrypt_reply(subpointer, SB_LEN());
                        break;
                case ENCRYPT_ENC_KEYID:
                        if (my_want_state_is_dont(TELOPT_ENCRYPT))
                                return;
                        encrypt_enc_keyid(subpointer, SB_LEN());
                        break;
                case ENCRYPT_DEC_KEYID:
                        if (my_want_state_is_wont(TELOPT_ENCRYPT))
                                return;
                        encrypt_dec_keyid(subpointer, SB_LEN());
                        break;
                default:
                        break;
                }
                break;
#endif  /* ENCRYPTION */
    default:
        break;
    }
}

static unsigned char str_lm[] = { IAC, SB, TELOPT_LINEMODE, 0, 0, IAC, SE };

void
lm_will(unsigned char *cmd, int len)
{
    if (len < 1) {
/*@*/   printf("lm_will: no command!!!\n");     /* Should not happen... */
        return;
    }
    switch(cmd[0]) {
    case LM_FORWARDMASK:        /* We shouldn't ever get this... */
    default:
        str_lm[3] = DONT;
        str_lm[4] = cmd[0];
        if (NETROOM() > (int)sizeof(str_lm)) {
            ring_supply_data(&netoring, str_lm, sizeof(str_lm));
            printsub('>', &str_lm[2], sizeof(str_lm)-2);
        }
/*@*/   else printf("lm_will: not enough room in buffer\n");
        break;
    }
}

void
lm_wont(unsigned char *cmd, int len)
{
    if (len < 1) {
/*@*/   printf("lm_wont: no command!!!\n");     /* Should not happen... */
        return;
    }
    switch(cmd[0]) {
    case LM_FORWARDMASK:        /* We shouldn't ever get this... */
    default:
        /* We are always DONT, so don't respond */
        return;
    }
}

void
lm_do(unsigned char *cmd, int len)
{
    if (len < 1) {
/*@*/   printf("lm_do: no command!!!\n");       /* Should not happen... */
        return;
    }
    switch(cmd[0]) {
    case LM_FORWARDMASK:
    default:
        str_lm[3] = WONT;
        str_lm[4] = cmd[0];
        if (NETROOM() > (int)sizeof(str_lm)) {
            ring_supply_data(&netoring, str_lm, sizeof(str_lm));
            printsub('>', &str_lm[2], sizeof(str_lm)-2);
        }
/*@*/   else printf("lm_do: not enough room in buffer\n");
        break;
    }
}

void
lm_dont(unsigned char *cmd, int len)
{
    if (len < 1) {
/*@*/   printf("lm_dont: no command!!!\n");     /* Should not happen... */
        return;
    }
    switch(cmd[0]) {
    case LM_FORWARDMASK:
    default:
        /* we are always WONT, so don't respond */
        break;
    }
}

static unsigned char str_lm_mode[] = {
        IAC, SB, TELOPT_LINEMODE, LM_MODE, 0, IAC, SE
};

void
lm_mode(unsigned char *cmd, int len, int init)
{
        if (len != 1)
                return;
        if ((linemode&MODE_MASK&~MODE_ACK) == *cmd)
                return;
        if (*cmd&MODE_ACK)
                return;
        linemode = *cmd&(MODE_MASK&~MODE_ACK);
        str_lm_mode[4] = linemode;
        if (!init)
            str_lm_mode[4] |= MODE_ACK;
        if (NETROOM() > (int)sizeof(str_lm_mode)) {
            ring_supply_data(&netoring, str_lm_mode, sizeof(str_lm_mode));
            printsub('>', &str_lm_mode[2], sizeof(str_lm_mode)-2);
        }
/*@*/   else printf("lm_mode: not enough room in buffer\n");
        setconnmode(0); /* set changed mode */
}



/*
 * slc()
 * Handle special character suboption of LINEMODE.
 */

struct spc {
        cc_t val;
        cc_t *valp;
        char flags;     /* Current flags & level */
        char mylevel;   /* Maximum level & flags */
} spc_data[NSLC+1];

#define SLC_IMPORT      0
#define SLC_EXPORT      1
#define SLC_RVALUE      2
static int slc_mode = SLC_EXPORT;

void
slc_init(void)
{
        struct spc *spcp;

        localchars = 1;
        for (spcp = spc_data; spcp < &spc_data[NSLC+1]; spcp++) {
                spcp->val = 0;
                spcp->valp = 0;
                spcp->flags = spcp->mylevel = SLC_NOSUPPORT;
        }

#define initfunc(func, flags) { \
                                        spcp = &spc_data[func]; \
                                        if ((spcp->valp = tcval(func))) { \
                                            spcp->val = *spcp->valp; \
                                            spcp->mylevel = SLC_VARIABLE|flags; \
                                        } else { \
                                            spcp->val = 0; \
                                            spcp->mylevel = SLC_DEFAULT; \
                                        } \
                                    }

        initfunc(SLC_SYNCH, 0);
        /* No BRK */
        initfunc(SLC_AO, 0);
        initfunc(SLC_AYT, 0);
        /* No EOR */
        initfunc(SLC_ABORT, SLC_FLUSHIN|SLC_FLUSHOUT);
        initfunc(SLC_EOF, 0);
#ifndef SYSV_TERMIO
        initfunc(SLC_SUSP, SLC_FLUSHIN);
#endif
        initfunc(SLC_EC, 0);
        initfunc(SLC_EL, 0);
#ifndef SYSV_TERMIO
        initfunc(SLC_EW, 0);
        initfunc(SLC_RP, 0);
        initfunc(SLC_LNEXT, 0);
#endif
        initfunc(SLC_XON, 0);
        initfunc(SLC_XOFF, 0);
#ifdef  SYSV_TERMIO
        spc_data[SLC_XON].mylevel = SLC_CANTCHANGE;
        spc_data[SLC_XOFF].mylevel = SLC_CANTCHANGE;
#endif
        initfunc(SLC_FORW1, 0);
#ifdef  USE_TERMIO
        initfunc(SLC_FORW2, 0);
        /* No FORW2 */
#endif

        initfunc(SLC_IP, SLC_FLUSHIN|SLC_FLUSHOUT);
#undef  initfunc

        if (slc_mode == SLC_EXPORT)
                slc_export();
        else
                slc_import(1);

}

void
slcstate(void)
{
    printf("Special characters are %s values\n",
                slc_mode == SLC_IMPORT ? "remote default" :
                slc_mode == SLC_EXPORT ? "local" :
                                         "remote");
}

void
slc_mode_export(void)
{
    slc_mode = SLC_EXPORT;
    if (my_state_is_will(TELOPT_LINEMODE))
        slc_export();
}

void
slc_mode_import(int def)
{
    slc_mode = def ? SLC_IMPORT : SLC_RVALUE;
    if (my_state_is_will(TELOPT_LINEMODE))
        slc_import(def);
}

unsigned char slc_import_val[] = {
        IAC, SB, TELOPT_LINEMODE, LM_SLC, 0, SLC_VARIABLE, 0, IAC, SE
};
unsigned char slc_import_def[] = {
        IAC, SB, TELOPT_LINEMODE, LM_SLC, 0, SLC_DEFAULT, 0, IAC, SE
};

void
slc_import(int def)
{
    if (NETROOM() > (int)sizeof(slc_import_val)) {
        if (def) {
            ring_supply_data(&netoring, slc_import_def, sizeof(slc_import_def));
            printsub('>', &slc_import_def[2], sizeof(slc_import_def)-2);
        } else {
            ring_supply_data(&netoring, slc_import_val, sizeof(slc_import_val));
            printsub('>', &slc_import_val[2], sizeof(slc_import_val)-2);
        }
    }
/*@*/ else printf("slc_import: not enough room\n");
}

void
slc_export(void)
{
    struct spc *spcp;

    TerminalDefaultChars();

    slc_start_reply();
    for (spcp = &spc_data[1]; spcp < &spc_data[NSLC+1]; spcp++) {
        if (spcp->mylevel != SLC_NOSUPPORT) {
            if (spcp->val == (cc_t)(_POSIX_VDISABLE))
                spcp->flags = SLC_NOSUPPORT;
            else
                spcp->flags = spcp->mylevel;
            if (spcp->valp)
                spcp->val = *spcp->valp;
            slc_add_reply(spcp - spc_data, spcp->flags, spcp->val);
        }
    }
    slc_end_reply();
    (void)slc_update();
    setconnmode(1);     /* Make sure the character values are set */
}

void
slc(unsigned char *cp, int len)
{
        struct spc *spcp;
        int func,level;

        slc_start_reply();

        for (; len >= 3; len -=3, cp +=3) {

                func = cp[SLC_FUNC];

                if (func == 0) {
                        /*
                         * Client side: always ignore 0 function.
                         */
                        continue;
                }
                if (func > NSLC) {
                        if ((cp[SLC_FLAGS] & SLC_LEVELBITS) != SLC_NOSUPPORT)
                                slc_add_reply(func, SLC_NOSUPPORT, 0);
                        continue;
                }

                spcp = &spc_data[func];

                level = cp[SLC_FLAGS]&(SLC_LEVELBITS|SLC_ACK);

                if ((cp[SLC_VALUE] == (unsigned char)spcp->val) &&
                    ((level&SLC_LEVELBITS) == (spcp->flags&SLC_LEVELBITS))) {
                        continue;
                }

                if (level == (SLC_DEFAULT|SLC_ACK)) {
                        /*
                         * This is an error condition, the SLC_ACK
                         * bit should never be set for the SLC_DEFAULT
                         * level.  Our best guess to recover is to
                         * ignore the SLC_ACK bit.
                         */
                        cp[SLC_FLAGS] &= ~SLC_ACK;
                }

                if (level == ((spcp->flags&SLC_LEVELBITS)|SLC_ACK)) {
                        spcp->val = (cc_t)cp[SLC_VALUE];
                        spcp->flags = cp[SLC_FLAGS];    /* include SLC_ACK */
                        continue;
                }

                level &= ~SLC_ACK;

                if (level <= (spcp->mylevel&SLC_LEVELBITS)) {
                        spcp->flags = cp[SLC_FLAGS]|SLC_ACK;
                        spcp->val = (cc_t)cp[SLC_VALUE];
                }
                if (level == SLC_DEFAULT) {
                        if ((spcp->mylevel&SLC_LEVELBITS) != SLC_DEFAULT)
                                spcp->flags = spcp->mylevel;
                        else
                                spcp->flags = SLC_NOSUPPORT;
                }
                slc_add_reply(func, spcp->flags, spcp->val);
        }
        slc_end_reply();
        if (slc_update())
                setconnmode(1); /* set the  new character values */
}

void
slc_check(void)
{
    struct spc *spcp;

    slc_start_reply();
    for (spcp = &spc_data[1]; spcp < &spc_data[NSLC+1]; spcp++) {
        if (spcp->valp && spcp->val != *spcp->valp) {
            spcp->val = *spcp->valp;
            if (spcp->val == (cc_t)(_POSIX_VDISABLE))
                spcp->flags = SLC_NOSUPPORT;
            else
                spcp->flags = spcp->mylevel;
            slc_add_reply(spcp - spc_data, spcp->flags, spcp->val);
        }
    }
    slc_end_reply();
    setconnmode(1);
}

unsigned char slc_reply[128];
unsigned char const * const slc_reply_eom = &slc_reply[sizeof(slc_reply)];
unsigned char *slc_replyp;

void
slc_start_reply(void)
{
        slc_replyp = slc_reply;
        *slc_replyp++ = IAC;
        *slc_replyp++ = SB;
        *slc_replyp++ = TELOPT_LINEMODE;
        *slc_replyp++ = LM_SLC;
}

void
slc_add_reply(unsigned char func, unsigned char flags, cc_t value)
{
        /* A sequence of up to 6 bytes my be written for this member of the SLC
         * suboption list by this function.  The end of negotiation command,
         * which is written by slc_end_reply(), will require 2 additional
         * bytes.  Do not proceed unless there is sufficient space for these
         * items.
         */
        if (&slc_replyp[6+2] > slc_reply_eom)
                return;
        if ((*slc_replyp++ = func) == IAC)
                *slc_replyp++ = IAC;
        if ((*slc_replyp++ = flags) == IAC)
                *slc_replyp++ = IAC;
        if ((*slc_replyp++ = (unsigned char)value) == IAC)
                *slc_replyp++ = IAC;
}

void
slc_end_reply(void)
{
    int len;

    /* The end of negotiation command requires 2 bytes. */
    if (&slc_replyp[2] > slc_reply_eom)
            return;
    *slc_replyp++ = IAC;
    *slc_replyp++ = SE;
    len = slc_replyp - slc_reply;
    if (len <= 6)
        return;
    if (NETROOM() > len) {
        ring_supply_data(&netoring, slc_reply, slc_replyp - slc_reply);
        printsub('>', &slc_reply[2], slc_replyp - slc_reply - 2);
    }
/*@*/else printf("slc_end_reply: not enough room\n");
}

int
slc_update(void)
{
        struct spc *spcp;
        int need_update = 0;

        for (spcp = &spc_data[1]; spcp < &spc_data[NSLC+1]; spcp++) {
                if (!(spcp->flags&SLC_ACK))
                        continue;
                spcp->flags &= ~SLC_ACK;
                if (spcp->valp && (*spcp->valp != spcp->val)) {
                        *spcp->valp = spcp->val;
                        need_update = 1;
                }
        }
        return(need_update);
}

#ifdef  OLD_ENVIRON
# ifdef ENV_HACK
/*
 * Earlier version of telnet/telnetd from the BSD code had
 * the definitions of VALUE and VAR reversed.  To ensure
 * maximum interoperability, we assume that the server is
 * an older BSD server, until proven otherwise.  The newer
 * BSD servers should be able to handle either definition,
 * so it is better to use the wrong values if we don't
 * know what type of server it is.
 */
int env_auto = 1;
int old_env_var = OLD_ENV_VAR;
int old_env_value = OLD_ENV_VALUE;
# else
#  define old_env_var OLD_ENV_VAR
#  define old_env_value OLD_ENV_VALUE
# endif
#endif

void
env_opt(unsigned char *buf, int len)
{
        unsigned char *ep = 0, *epc = 0;
        int i;

        switch(buf[0]&0xff) {
        case TELQUAL_SEND:
                env_opt_start();
                if (len == 1) {
                        env_opt_add(NULL);
                } else for (i = 1; i < len; i++) {
                        switch (buf[i]&0xff) {
#ifdef  OLD_ENVIRON
                        case OLD_ENV_VAR:
# ifdef ENV_HACK
                                if (telopt_environ == TELOPT_OLD_ENVIRON
                                    && env_auto) {
                                        /* Server has the same definitions */
                                        old_env_var = OLD_ENV_VAR;
                                        old_env_value = OLD_ENV_VALUE;
                                }
                                /* FALLTHROUGH */
# endif
                        case OLD_ENV_VALUE:
                                /*
                                 * Although OLD_ENV_VALUE is not legal, we will
                                 * still recognize it, just in case it is an
                                 * old server that has VAR & VALUE mixed up...
                                 */
                                /* FALLTHROUGH */
#else
                        case NEW_ENV_VAR:
#endif
                        case ENV_USERVAR:
                                if (ep) {
                                        *epc = 0;
                                        env_opt_add(ep);
                                }
                                ep = epc = &buf[i+1];
                                break;
                        case ENV_ESC:
                                i++;
                                /*FALLTHROUGH*/
                        default:
                                if (epc)
                                        *epc++ = buf[i];
                                break;
                        }
                }
                if (ep) {
                        *epc = 0;
                        env_opt_add(ep);
                }
                env_opt_end(1);
                break;

        case TELQUAL_IS:
        case TELQUAL_INFO:
                /* Ignore for now.  We shouldn't get it anyway. */
                break;

        default:
                break;
        }
}

#define OPT_REPLY_SIZE  (2 * SUBBUFSIZE)
unsigned char *opt_reply = NULL;
unsigned char *opt_replyp;
unsigned char *opt_replyend;

void
env_opt_start(void)
{
        if (opt_reply)
                opt_reply = (unsigned char *)realloc(opt_reply, OPT_REPLY_SIZE);
        else
                opt_reply = (unsigned char *)malloc(OPT_REPLY_SIZE);
        if (opt_reply == NULL) {
/*@*/           printf("env_opt_start: malloc()/realloc() failed!!!\n");
                opt_reply = opt_replyp = opt_replyend = NULL;
                return;
        }
        opt_replyp = opt_reply;
        opt_replyend = opt_reply + OPT_REPLY_SIZE;
        *opt_replyp++ = IAC;
        *opt_replyp++ = SB;
        *opt_replyp++ = telopt_environ;
        *opt_replyp++ = TELQUAL_IS;
}

void
env_opt_start_info(void)
{
        env_opt_start();
        if (opt_replyp)
            opt_replyp[-1] = TELQUAL_INFO;
}

void
env_opt_add(unsigned char *ep)
{
        unsigned char *vp, c;

        if (opt_reply == NULL)          /*XXX*/
                return;                 /*XXX*/

        if (ep == NULL || *ep == '\0') {
                /* Send user defined variables first. */
                env_default(1, 0);
                while ((ep = env_default(0, 0)))
                        env_opt_add(ep);

                /* Now add the list of well know variables.  */
                env_default(1, 1);
                while ((ep = env_default(0, 1)))
                        env_opt_add(ep);
                return;
        }
        vp = env_getvalue(ep);
        if (opt_replyp + (vp ? 2 * strlen((char *)vp) : 0) +
                                2 * strlen((char *)ep) + 6 > opt_replyend)
        {
                int len;
                opt_replyend += OPT_REPLY_SIZE;
                len = opt_replyend - opt_reply;
                opt_reply = (unsigned char *)realloc(opt_reply, len);
                if (opt_reply == NULL) {
/*@*/                   printf("env_opt_add: realloc() failed!!!\n");
                        opt_reply = opt_replyp = opt_replyend = NULL;
                        return;
                }
                opt_replyp = opt_reply + len - (opt_replyend - opt_replyp);
                opt_replyend = opt_reply + len;
        }
        if (opt_welldefined(ep))
#ifdef  OLD_ENVIRON
                if (telopt_environ == TELOPT_OLD_ENVIRON)
                        *opt_replyp++ = old_env_var;
                else
#endif
                        *opt_replyp++ = NEW_ENV_VAR;
        else
                *opt_replyp++ = ENV_USERVAR;
        for (;;) {
                while ((c = *ep++)) {
                        if (opt_replyp + (2 + 2) > opt_replyend)
                                return;
                        switch(c&0xff) {
                        case IAC:
                                *opt_replyp++ = IAC;
                                break;
                        case NEW_ENV_VAR:
                        case NEW_ENV_VALUE:
                        case ENV_ESC:
                        case ENV_USERVAR:
                                *opt_replyp++ = ENV_ESC;
                                break;
                        }
                        *opt_replyp++ = c;
                }
                if ((ep = vp)) {
                        if (opt_replyp + (1 + 2 + 2) > opt_replyend)
                                return;
#ifdef  OLD_ENVIRON
                        if (telopt_environ == TELOPT_OLD_ENVIRON)
                                *opt_replyp++ = old_env_value;
                        else
#endif
                                *opt_replyp++ = NEW_ENV_VALUE;
                        vp = NULL;
                } else
                        break;
        }
}

int
opt_welldefined(const char *ep)
{
        if ((strcmp(ep, "USER") == 0) ||
            (strcmp(ep, "DISPLAY") == 0) ||
            (strcmp(ep, "PRINTER") == 0) ||
            (strcmp(ep, "SYSTEMTYPE") == 0) ||
            (strcmp(ep, "JOB") == 0) ||
            (strcmp(ep, "ACCT") == 0))
                return(1);
        return(0);
}

void
env_opt_end(int emptyok)
{
        int len;

        if (opt_replyp + 2 > opt_replyend)
                return;
        len = opt_replyp + 2 - opt_reply;
        if (emptyok || len > 6) {
                *opt_replyp++ = IAC;
                *opt_replyp++ = SE;
                if (NETROOM() > len) {
                        ring_supply_data(&netoring, opt_reply, len);
                        printsub('>', &opt_reply[2], len - 2);
                }
/*@*/           else printf("slc_end_reply: not enough room\n");
        }
        if (opt_reply) {
                free(opt_reply);
                opt_reply = opt_replyp = opt_replyend = NULL;
        }
}



int
telrcv(void)
{
    int c;
    int scc;
    unsigned char *sbp;
    int count;
    int returnValue = 0;

    scc = 0;
    count = 0;
    while (TTYROOM() > 2) {
        if (scc == 0) {
            if (count) {
                ring_consumed(&netiring, count);
                returnValue = 1;
                count = 0;
            }
            sbp = netiring.consume;
            scc = ring_full_consecutive(&netiring);
            if (scc == 0) {
                /* No more data coming in */
                break;
            }
        }

        c = *sbp++ & 0xff, scc--; count++;
#ifdef  ENCRYPTION
        if (decrypt_input)
                c = (*decrypt_input)(c);
#endif  /* ENCRYPTION */

        switch (telrcv_state) {

        case TS_CR:
            telrcv_state = TS_DATA;
            if (c == '\0') {
                break;  /* Ignore \0 after CR */
            }
            else if ((c == '\n') && my_want_state_is_dont(TELOPT_ECHO) && !crmod) {
                TTYADD(c);
                break;
            }
            /* FALLTHROUGH */

        case TS_DATA:
            if (c == IAC && telnetport >= 0) {
                telrcv_state = TS_IAC;
                break;
            }
                    /*
                     * The 'crmod' hack (see following) is needed
                     * since we can't * set CRMOD on output only.
                     * Machines like MULTICS like to send \r without
                     * \n; since we must turn off CRMOD to get proper
                     * input, the mapping is done here (sigh).
                     */
            if ((c == '\r') && my_want_state_is_dont(TELOPT_BINARY)) {
                if (scc > 0) {
                    c = *sbp&0xff;
#ifdef  ENCRYPTION
                    if (decrypt_input)
                        c = (*decrypt_input)(c);
#endif  /* ENCRYPTION */
                    if (c == 0) {
                        sbp++, scc--; count++;
                        /* a "true" CR */
                        TTYADD('\r');
                    } else if (my_want_state_is_dont(TELOPT_ECHO) &&
                                        (c == '\n')) {
                        sbp++, scc--; count++;
                        TTYADD('\n');
                    } else {
#ifdef  ENCRYPTION
                        if (decrypt_input)
                            (*decrypt_input)(-1);
#endif  /* ENCRYPTION */

                        TTYADD('\r');
                        if (crmod) {
                                TTYADD('\n');
                        }
                    }
                } else {
                    telrcv_state = TS_CR;
                    TTYADD('\r');
                    if (crmod) {
                            TTYADD('\n');
                    }
                }
            } else {
                TTYADD(c);
            }
            continue;

        case TS_IAC:
process_iac:
            switch (c) {

            case WILL:
                telrcv_state = TS_WILL;
                continue;

            case WONT:
                telrcv_state = TS_WONT;
                continue;

            case DO:
                telrcv_state = TS_DO;
                continue;

            case DONT:
                telrcv_state = TS_DONT;
                continue;

            case DM:
                    /*
                     * We may have missed an urgent notification,
                     * so make sure we flush whatever is in the
                     * buffer currently.
                     */
                printoption("RCVD", IAC, DM);
                SYNCHing = 1;
                (void) ttyflush(1);
                SYNCHing = stilloob();
                settimer(gotDM);
                break;

            case SB:
                SB_CLEAR();
                telrcv_state = TS_SB;
                continue;

            case IAC:
                TTYADD(IAC);
                break;

            case NOP:
            case GA:
            default:
                printoption("RCVD", IAC, c);
                break;
            }
            telrcv_state = TS_DATA;
            continue;

        case TS_WILL:
            printoption("RCVD", WILL, c);
            willoption(c);
            telrcv_state = TS_DATA;
            continue;

        case TS_WONT:
            printoption("RCVD", WONT, c);
            wontoption(c);
            telrcv_state = TS_DATA;
            continue;

        case TS_DO:
            printoption("RCVD", DO, c);
            dooption(c);
            if (c == TELOPT_NAWS) {
                sendnaws();
            } else if (c == TELOPT_LFLOW) {
                localflow = 1;
                setcommandmode();
                setconnmode(0);
            }
            telrcv_state = TS_DATA;
            continue;

        case TS_DONT:
            printoption("RCVD", DONT, c);
            dontoption(c);
            flushline = 1;
            setconnmode(0);     /* set new tty mode (maybe) */
            telrcv_state = TS_DATA;
            continue;

        case TS_SB:
            if (c == IAC) {
                telrcv_state = TS_SE;
            } else {
                SB_ACCUM(c);
            }
            continue;

        case TS_SE:
            if (c != SE) {
                if (c != IAC) {
                    /*
                     * This is an error.  We only expect to get
                     * "IAC IAC" or "IAC SE".  Several things may
                     * have happend.  An IAC was not doubled, the
                     * IAC SE was left off, or another option got
                     * inserted into the suboption are all possibilities.
                     * If we assume that the IAC was not doubled,
                     * and really the IAC SE was left off, we could
                     * get into an infinate loop here.  So, instead,
                     * we terminate the suboption, and process the
                     * partial suboption if we can.
                     */
                    SB_ACCUM(IAC);
                    SB_ACCUM(c);
                    subpointer -= 2;
                    SB_TERM();

                    printoption("In SUBOPTION processing, RCVD", IAC, c);
                    suboption();        /* handle sub-option */
                    telrcv_state = TS_IAC;
                    goto process_iac;
                }
                SB_ACCUM(c);
                telrcv_state = TS_SB;
            } else {
                SB_ACCUM(IAC);
                SB_ACCUM(SE);
                subpointer -= 2;
                SB_TERM();
                suboption();    /* handle sub-option */
                telrcv_state = TS_DATA;
            }
        }
    }
    if (count)
        ring_consumed(&netiring, count);
    return returnValue||count;
}

static int bol = 1, local = 0;

int
rlogin_susp(void)
{
    if (local) {
        local = 0;
        bol = 1;
        command(0, "z\n", 2);
        return(1);
    }
    return(0);
}

static int
telsnd(void)
{
    int tcc;
    int count;
    int returnValue = 0;
    unsigned char *tbp;

    tcc = 0;
    count = 0;
    while (NETROOM() > 2) {
        int sc;
        int c;

        if (tcc == 0) {
            if (count) {
                ring_consumed(&ttyiring, count);
                returnValue = 1;
                count = 0;
            }
            tbp = ttyiring.consume;
            tcc = ring_full_consecutive(&ttyiring);
            if (tcc == 0) {
                break;
            }
        }
        c = *tbp++ & 0xff, sc = strip(c), tcc--; count++;
        if (rlogin != _POSIX_VDISABLE) {
                if (bol) {
                        bol = 0;
                        if (sc == rlogin) {
                                local = 1;
                                continue;
                        }
                } else if (local) {
                        local = 0;
                        if (sc == '.' || c == termEofChar) {
                                bol = 1;
                                command(0, "close\n", 6);
                                continue;
                        }
                        if (sc == termSuspChar) {
                                bol = 1;
                                command(0, "z\n", 2);
                                continue;
                        }
                        if (sc == escape) {
                                command(0, tbp, tcc);
                                bol = 1;
                                count += tcc;
                                tcc = 0;
                                flushline = 1;
                                break;
                        }
                        if (sc != rlogin) {
                                ++tcc;
                                --tbp;
                                --count;
                                c = sc = rlogin;
                        }
                }
                if ((sc == '\n') || (sc == '\r'))
                        bol = 1;
        } else if (escape != _POSIX_VDISABLE && sc == escape) {
            /*
             * Double escape is a pass through of a single escape character.
             */
            if (tcc && strip(*tbp) == escape) {
                tbp++;
                tcc--;
                count++;
                bol = 0;
            } else {
                command(0, (char *)tbp, tcc);
                bol = 1;
                count += tcc;
                tcc = 0;
                flushline = 1;
                break;
            }
        } else
            bol = 0;
#ifdef  KLUDGELINEMODE
        if (kludgelinemode && (globalmode&MODE_EDIT) && (sc == echoc)) {
            if (tcc > 0 && strip(*tbp) == echoc) {
                tcc--; tbp++; count++;
            } else {
                dontlecho = !dontlecho;
                settimer(echotoggle);
                setconnmode(0);
                flushline = 1;
                break;
            }
        }
#endif
        if (MODE_LOCAL_CHARS(globalmode)) {
            if (TerminalSpecialChars(sc) == 0) {
                bol = 1;
                break;
            }
        }
        if (my_want_state_is_wont(TELOPT_BINARY)) {
            switch (c) {
            case '\n':
                    /*
                     * If we are in CRMOD mode (\r ==> \n)
                     * on our local machine, then probably
                     * a newline (unix) is CRLF (TELNET).
                     */
                if (MODE_LOCAL_CHARS(globalmode)) {
                    NETADD('\r');
                }
                NETADD('\n');
                bol = flushline = 1;
                break;
            case '\r':
                if (!crlf) {
                    NET2ADD('\r', '\0');
                } else {
                    NET2ADD('\r', '\n');
                }
                bol = flushline = 1;
                break;
            case IAC:
                NET2ADD(IAC, IAC);
                break;
            default:
                NETADD(c);
                break;
            }
        } else if (c == IAC) {
            NET2ADD(IAC, IAC);
        } else {
            NETADD(c);
        }
    }
    if (count)
        ring_consumed(&ttyiring, count);
    return returnValue||count;          /* Non-zero if we did anything */
}

/*
 * Scheduler()
 *
 * Try to do something.
 *
 * If we do something useful, return 1; else return 0.
 *
 */

static int
Scheduler(int block)
{
                /* One wants to be a bit careful about setting returnValue
                 * to one, since a one implies we did some useful work,
                 * and therefore probably won't be called to block next
                 */
    int returnValue;
    int netin, netout, netex, ttyin, ttyout;

    /* Decide which rings should be processed */

    netout = ring_full_count(&netoring) &&
            (flushline ||
                (my_want_state_is_wont(TELOPT_LINEMODE)
#ifdef  KLUDGELINEMODE
                        && (!kludgelinemode || my_want_state_is_do(TELOPT_SGA))
#endif
                ) ||
                        my_want_state_is_will(TELOPT_BINARY));
    ttyout = ring_full_count(&ttyoring);

    ttyin = ring_empty_count(&ttyiring) && (clienteof == 0);

    netin = !ISend && ring_empty_count(&netiring);

    netex = !SYNCHing;

    /* Call to system code to process rings */

    returnValue = process_rings(netin, netout, netex, ttyin, ttyout, !block);

    /* Now, look at the input rings, looking for work to do. */

    if (ring_full_count(&ttyiring)) {
            returnValue |= telsnd();
    }

    if (ring_full_count(&netiring)) {
        returnValue |= telrcv();
    }
    return returnValue;
}

#ifdef  AUTHENTICATION
#define __unusedhere
#else
#define __unusedhere __unused
#endif
/*
 * Select from tty and network...
 */
void
telnet(char *user __unusedhere)
{
    sys_telnet_init();

#ifdef  AUTHENTICATION
#ifdef  ENCRYPTION
    {
        static char local_host[256] = { 0 };

        if (!local_host[0]) {
                gethostname(local_host, sizeof(local_host));
                local_host[sizeof(local_host)-1] = 0;
        }
        auth_encrypt_init(local_host, hostname, "TELNET", 0);
        auth_encrypt_user(user);
    }
#endif
#endif
    if (telnetport > 0) {
#ifdef  AUTHENTICATION
        if (autologin)
                send_will(TELOPT_AUTHENTICATION, 1);
#endif
#ifdef  ENCRYPTION
        send_do(TELOPT_ENCRYPT, 1);
        send_will(TELOPT_ENCRYPT, 1);
#endif  /* ENCRYPTION */
        send_do(TELOPT_SGA, 1);
        send_will(TELOPT_TTYPE, 1);
        send_will(TELOPT_NAWS, 1);
        send_will(TELOPT_TSPEED, 1);
        send_will(TELOPT_LFLOW, 1);
        send_will(TELOPT_LINEMODE, 1);
        send_will(TELOPT_NEW_ENVIRON, 1);
        send_do(TELOPT_STATUS, 1);
        if (env_getvalue("DISPLAY"))
            send_will(TELOPT_XDISPLOC, 1);
        if (eight)
            tel_enter_binary(eight);
    }

    for (;;) {
        int schedValue;

        while ((schedValue = Scheduler(0)) != 0) {
            if (schedValue == -1) {
                setcommandmode();
                return;
            }
        }

        if (Scheduler(1) == -1) {
            setcommandmode();
            return;
        }
    }
}

#if     0       /* XXX - this not being in is a bug */
/*
 * nextitem()
 *
 *      Return the address of the next "item" in the TELNET data
 * stream.  This will be the address of the next character if
 * the current address is a user data character, or it will
 * be the address of the character following the TELNET command
 * if the current address is a TELNET IAC ("I Am a Command")
 * character.
 */

static char *
nextitem(char *current)
{
    if ((*current&0xff) != IAC) {
        return current+1;
    }
    switch (*(current+1)&0xff) {
    case DO:
    case DONT:
    case WILL:
    case WONT:
        return current+3;
    case SB:            /* loop forever looking for the SE */
        {
            char *look = current+2;

            for (;;) {
                if ((*look++&0xff) == IAC) {
                    if ((*look++&0xff) == SE) {
                        return look;
                    }
                }
            }
        }
    default:
        return current+2;
    }
}
#endif  /* 0 */

/*
 * netclear()
 *
 *      We are about to do a TELNET SYNCH operation.  Clear
 * the path to the network.
 *
 *      Things are a bit tricky since we may have sent the first
 * byte or so of a previous TELNET command into the network.
 * So, we have to scan the network buffer from the beginning
 * until we are up to where we want to be.
 *
 *      A side effect of what we do, just to keep things
 * simple, is to clear the urgent data pointer.  The principal
 * caller should be setting the urgent data pointer AFTER calling
 * us in any case.
 */

static void
netclear(void)
{
        /* Deleted */
}

/*
 * These routines add various telnet commands to the data stream.
 */

static void
doflush(void)
{
    NET2ADD(IAC, DO);
    NETADD(TELOPT_TM);
    flushline = 1;
    flushout = 1;
    (void) ttyflush(1);                 /* Flush/drop output */
    /* do printoption AFTER flush, otherwise the output gets tossed... */
    printoption("SENT", DO, TELOPT_TM);
}

void
xmitAO(void)
{
    NET2ADD(IAC, AO);
    printoption("SENT", IAC, AO);
    if (autoflush) {
        doflush();
    }
}

void
xmitEL(void)
{
    NET2ADD(IAC, EL);
    printoption("SENT", IAC, EL);
}

void
xmitEC(void)
{
    NET2ADD(IAC, EC);
    printoption("SENT", IAC, EC);
}

int
dosynch(char *ch __unused)
{
    netclear();                 /* clear the path to the network */
    NETADD(IAC);
    setneturg();
    NETADD(DM);
    printoption("SENT", IAC, DM);
    return 1;
}

int want_status_response = 0;

int
get_status(char *ch __unused)
{
    unsigned char tmp[16];
    unsigned char *cp;

    if (my_want_state_is_dont(TELOPT_STATUS)) {
        printf("Remote side does not support STATUS option\n");
        return 0;
    }
    cp = tmp;

    *cp++ = IAC;
    *cp++ = SB;
    *cp++ = TELOPT_STATUS;
    *cp++ = TELQUAL_SEND;
    *cp++ = IAC;
    *cp++ = SE;
    if (NETROOM() >= cp - tmp) {
        ring_supply_data(&netoring, tmp, cp-tmp);
        printsub('>', tmp+2, cp - tmp - 2);
    }
    ++want_status_response;
    return 1;
}

void
intp(void)
{
    NET2ADD(IAC, IP);
    printoption("SENT", IAC, IP);
    flushline = 1;
    if (autoflush) {
        doflush();
    }
    if (autosynch) {
        dosynch(NULL);
    }
}

void
sendbrk(void)
{
    NET2ADD(IAC, BREAK);
    printoption("SENT", IAC, BREAK);
    flushline = 1;
    if (autoflush) {
        doflush();
    }
    if (autosynch) {
        dosynch(NULL);
    }
}

void
sendabort(void)
{
    NET2ADD(IAC, ABORT);
    printoption("SENT", IAC, ABORT);
    flushline = 1;
    if (autoflush) {
        doflush();
    }
    if (autosynch) {
        dosynch(NULL);
    }
}

void
sendsusp(void)
{
    NET2ADD(IAC, SUSP);
    printoption("SENT", IAC, SUSP);
    flushline = 1;
    if (autoflush) {
        doflush();
    }
    if (autosynch) {
        dosynch(NULL);
    }
}

void
sendeof(void)
{
    NET2ADD(IAC, xEOF);
    printoption("SENT", IAC, xEOF);
}

void
sendayt(void)
{
    NET2ADD(IAC, AYT);
    printoption("SENT", IAC, AYT);
}

/*
 * Send a window size update to the remote system.
 */

void
sendnaws(void)
{
    long rows, cols;
    unsigned char tmp[16];
    unsigned char *cp;

    if (my_state_is_wont(TELOPT_NAWS))
        return;

#define PUTSHORT(cp, x) { if ((*cp++ = ((x)>>8)&0xff) == IAC) *cp++ = IAC; \
                            if ((*cp++ = ((x))&0xff) == IAC) *cp++ = IAC; }

    if (TerminalWindowSize(&rows, &cols) == 0) {        /* Failed */
        return;
    }

    cp = tmp;

    *cp++ = IAC;
    *cp++ = SB;
    *cp++ = TELOPT_NAWS;
    PUTSHORT(cp, cols);
    PUTSHORT(cp, rows);
    *cp++ = IAC;
    *cp++ = SE;
    if (NETROOM() >= cp - tmp) {
        ring_supply_data(&netoring, tmp, cp-tmp);
        printsub('>', tmp+2, cp - tmp - 2);
    }
}

void
tel_enter_binary(int rw)
{
    if (rw&1)
        send_do(TELOPT_BINARY, 1);
    if (rw&2)
        send_will(TELOPT_BINARY, 1);
}

void
tel_leave_binary(int rw)
{
    if (rw&1)
        send_dont(TELOPT_BINARY, 1);
    if (rw&2)
        send_wont(TELOPT_BINARY, 1);
}