root/usr.bin/telnet/commands.c
/*      $OpenBSD: commands.c,v 1.89 2024/08/26 21:34:32 op Exp $        */
/*      $NetBSD: commands.c,v 1.14 1996/03/24 22:03:48 jtk Exp $        */

/*
 * 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.
 */

#include "telnet_locl.h"

#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <arpa/inet.h>
#include <arpa/telnet.h>

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <netdb.h>
#include <pwd.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <limits.h>

char    *hostname;

typedef struct {
        char    *name;          /* command name */
        char    *help;          /* help string (NULL for no help) */
        int     (*handler)(int, char **);/* routine which executes command */
        int     needconnect;    /* Do we need to be connected to execute? */
} Command;

#define        MAXARGV         20

static char line[256];
static int margc;
static char *margv[MAXARGV+1];

static int
makeargv(void)
{
    char *cp, *cp2, c;
    char **argp = margv;
    int ret = 0;

    margc = 0;
    cp = line;
    while ((c = *cp)) {
        if (margc >= MAXARGV) {
            printf("too many arguments\n");
            ret = 1;
            break;
        }
        int inquote = 0;
        while (isspace((unsigned char)c))
            c = *++cp;
        if (c == '\0')
            break;
        *argp++ = cp;
        margc += 1;
        for (cp2 = cp; c != '\0'; c = *++cp) {
            if (inquote) {
                if (c == inquote) {
                    inquote = 0;
                    continue;
                }
            } else {
                if (c == '\\') {
                    if ((c = *++cp) == '\0')
                        break;
                } else if (c == '"') {
                    inquote = '"';
                    continue;
                } else if (c == '\'') {
                    inquote = '\'';
                    continue;
                } else if (isspace((unsigned char)c))
                    break;
            }
            *cp2++ = c;
        }
        *cp2 = '\0';
        if (c == '\0')
            break;
        cp++;
    }
    *argp++ = 0;
    return (ret);
}

/*
 * Make a character string into a number.
 *
 * Todo:  1.  Could take random integers (12, 0x12, 012, 0b1).
 */

static char
special(char *s)
{
        char c;
        char b;

        switch (*s) {
        case '^':
                b = *++s;
                if (b == '?') {
                    c = b | 0x40;               /* DEL */
                } else {
                    c = b & 0x1f;
                }
                break;
        default:
                c = *s;
                break;
        }
        return c;
}

/*
 * Construct a control character sequence
 * for a special character.
 */
static char *
control(cc_t c)
{
        static char buf[5];
        /*
         * The only way I could get the Sun 3.5 compiler
         * to shut up about
         *      if ((unsigned int)c >= 0x80)
         * was to assign "c" to an unsigned int variable...
         * Arggg....
         */
        unsigned int uic = (unsigned int)c;

        if (uic == 0x7f)
                return ("^?");
        if (c == (cc_t)_POSIX_VDISABLE) {
                return "off";
        }
        if (uic >= 0x80) {
                buf[0] = '\\';
                buf[1] = ((c>>6)&07) + '0';
                buf[2] = ((c>>3)&07) + '0';
                buf[3] = (c&07) + '0';
                buf[4] = 0;
        } else if (uic >= 0x20) {
                buf[0] = c;
                buf[1] = 0;
        } else {
                buf[0] = '^';
                buf[1] = '@'+c;
                buf[2] = 0;
        }
        return (buf);
}

/*
 *      The following are data structures and routines for
 *      the "send" command.
 *
 */

struct sendlist {
    char        *name;          /* How user refers to it (case independent) */
    char        *help;          /* Help information (0 ==> no help) */
    int         needconnect;    /* Need to be connected */
    int         narg;           /* Number of arguments */
    int         (*handler)();   /* Routine to perform (for special ops) */
    int         nbyte;          /* Number of bytes to send this command */
    int         what;           /* Character to be sent (<0 ==> special) */
};


static int
        send_esc(void),
        send_help(void),
        send_docmd(char *),
        send_dontcmd(char *),
        send_willcmd(char *),
        send_wontcmd(char *);

static struct sendlist Sendlist[] = {
    { "ao",     "Send Telnet Abort output",             1, 0, 0, 2, AO },
    { "ayt",    "Send Telnet 'Are You There'",          1, 0, 0, 2, AYT },
    { "brk",    "Send Telnet Break",                    1, 0, 0, 2, BREAK },
    { "break",  0,                                      1, 0, 0, 2, BREAK },
    { "ec",     "Send Telnet Erase Character",          1, 0, 0, 2, EC },
    { "el",     "Send Telnet Erase Line",               1, 0, 0, 2, EL },
    { "escape", "Send current escape character",        1, 0, send_esc, 1, 0 },
    { "ga",     "Send Telnet 'Go Ahead' sequence",      1, 0, 0, 2, GA },
    { "ip",     "Send Telnet Interrupt Process",        1, 0, 0, 2, IP },
    { "intp",   0,                                      1, 0, 0, 2, IP },
    { "interrupt", 0,                                   1, 0, 0, 2, IP },
    { "intr",   0,                                      1, 0, 0, 2, IP },
    { "nop",    "Send Telnet 'No operation'",           1, 0, 0, 2, NOP },
    { "eor",    "Send Telnet 'End of Record'",          1, 0, 0, 2, EOR },
    { "abort",  "Send Telnet 'Abort Process'",          1, 0, 0, 2, ABORT },
    { "susp",   "Send Telnet 'Suspend Process'",        1, 0, 0, 2, SUSP },
    { "eof",    "Send Telnet End of File Character",    1, 0, 0, 2, xEOF },
    { "synch",  "Perform Telnet 'Synch operation'",     1, 0, dosynch, 2, 0 },
    { "getstatus", "Send request for STATUS",           1, 0, get_status, 6, 0 },
    { "?",      "Display send options",                 0, 0, send_help, 0, 0 },
    { "help",   0,                                      0, 0, send_help, 0, 0 },
    { "do",     0,                                      0, 1, send_docmd, 3, 0 },
    { "dont",   0,                                      0, 1, send_dontcmd, 3, 0 },
    { "will",   0,                                      0, 1, send_willcmd, 3, 0 },
    { "wont",   0,                                      0, 1, send_wontcmd, 3, 0 },
    { 0 }
};

#define GETSEND(name) ((struct sendlist *) genget(name, (char **) Sendlist, \
                                sizeof(struct sendlist)))

static int
sendcmd(int argc, char **argv)
{
    int count;          /* how many bytes we are going to need to send */
    int i;
    struct sendlist *s; /* pointer to current command */
    int success = 0;
    int needconnect = 0;

    if (argc < 2) {
        printf("need at least one argument for 'send' command\r\n");
        printf("'send ?' for help\r\n");
        return 0;
    }
    /*
     * First, validate all the send arguments.
     * In addition, we see how much space we are going to need, and
     * whether or not we will be doing a "SYNCH" operation (which
     * flushes the network queue).
     */
    count = 0;
    for (i = 1; i < argc; i++) {
        s = GETSEND(argv[i]);
        if (s == 0) {
            printf("Unknown send argument '%s'\r\n'send ?' for help.\r\n",
                        argv[i]);
            return 0;
        } else if (Ambiguous(s)) {
            printf("Ambiguous send argument '%s'\r\n'send ?' for help.\r\n",
                        argv[i]);
            return 0;
        }
        if (i + s->narg >= argc) {
            fprintf(stderr,
            "Need %d argument%s to 'send %s' command.  'send %s ?' for help.\r\n",
                s->narg, s->narg == 1 ? "" : "s", s->name, s->name);
            return 0;
        }
        count += s->nbyte;
        if (s->handler == send_help) {
            send_help();
            return 0;
        }

        i += s->narg;
        needconnect += s->needconnect;
    }
    if (!connected && needconnect) {
        printf("?Need to be connected first.\r\n");
        printf("'send ?' for help\r\n");
        return 0;
    }
    /* Now, do we have enough room? */
    if (NETROOM() < count) {
        printf("There is not enough room in the buffer TO the network\r\n");
        printf("to process your request.  Nothing will be done.\r\n");
        printf("('send synch' will throw away most data in the network\r\n");
        printf("buffer, if this might help.)\r\n");
        return 0;
    }
    /* OK, they are all OK, now go through again and actually send */
    count = 0;
    for (i = 1; i < argc; i++) {
        if ((s = GETSEND(argv[i])) == 0) {
            fprintf(stderr, "Telnet 'send' error - argument disappeared!\r\n");
            quit();
        }
        if (s->handler) {
            count++;
            success += (*s->handler)((s->narg > 0) ? argv[i+1] : 0,
                                  (s->narg > 1) ? argv[i+2] : 0);
            i += s->narg;
        } else {
            NET2ADD(IAC, s->what);
            printoption("SENT", IAC, s->what);
        }
    }
    return (count == success);
}

static int send_tncmd(void (*func)(int, int), char *cmd, char *name);

static int
send_esc(void)
{
    NETADD(escape);
    return 1;
}

static int
send_docmd(char *name)
{
    return(send_tncmd(send_do, "do", name));
}

static int
send_dontcmd(char *name)
{
    return(send_tncmd(send_dont, "dont", name));
}

static int
send_willcmd(char *name)
{
    return(send_tncmd(send_will, "will", name));
}

static int
send_wontcmd(char *name)
{
    return(send_tncmd(send_wont, "wont", name));
}

int
send_tncmd(void (*func)(int, int), char *cmd, char *name)
{
    char **cpp;
    extern char *telopts[];
    const char *errstr;
    int val = 0;

    if (isprefix(name, "help") || isprefix(name, "?")) {
        int col, len;

        printf("Usage: send %s <value|option>\r\n", cmd);
        printf("\"value\" must be from 0 to 255\r\n");
        printf("Valid options are:\r\n\t");

        col = 8;
        for (cpp = telopts; *cpp; cpp++) {
            len = strlen(*cpp) + 3;
            if (col + len > 65) {
                printf("\r\n\t");
                col = 8;
            }
            printf(" \"%s\"", *cpp);
            col += len;
        }
        printf("\r\n");
        return 0;
    }
    cpp = (char **)genget(name, telopts, sizeof(char *));
    if (Ambiguous(cpp)) {
        fprintf(stderr,"'%s': ambiguous argument ('send %s ?' for help).\r\n",
                                        name, cmd);
        return 0;
    }
    if (cpp) {
        val = cpp - telopts;
    } else {
        val = strtonum(name, 0, 255, &errstr);
        if (errstr) {
            fprintf(stderr, "'%s': %s ('send %s ?' for help).\r\n",
                                        name, errstr, cmd);
            return 0;
        }
    }
    if (!connected) {
        printf("?Need to be connected first.\r\n");
        return 0;
    }
    (*func)(val, 1);
    return 1;
}

static int
send_help(void)
{
    struct sendlist *s; /* pointer to current command */
    for (s = Sendlist; s->name; s++) {
        if (s->help)
            printf("%-15s %s\r\n", s->name, s->help);
    }
    return(0);
}

/*
 * The following are the routines and data structures referred
 * to by the arguments to the "toggle" command.
 */

static int
lclchars(int unused)
{
    donelclchars = 1;
    return 1;
}

static int
togcrlf(int unused)
{
    if (crlf) {
        printf("Will send carriage returns as telnet <CR><LF>.\r\n");
    } else {
        printf("Will send carriage returns as telnet <CR><NUL>.\r\n");
    }
    return 1;
}

int binmode;

static int
togbinary(int val)
{
    donebinarytoggle = 1;

    if (val >= 0) {
        binmode = val;
    } else {
        if (my_want_state_is_will(TELOPT_BINARY) &&
                                my_want_state_is_do(TELOPT_BINARY)) {
            binmode = 1;
        } else if (my_want_state_is_wont(TELOPT_BINARY) &&
                                my_want_state_is_dont(TELOPT_BINARY)) {
            binmode = 0;
        }
        val = binmode ? 0 : 1;
    }

    if (val == 1) {
        if (my_want_state_is_will(TELOPT_BINARY) &&
                                        my_want_state_is_do(TELOPT_BINARY)) {
            printf("Already operating in binary mode with remote host.\r\n");
        } else {
            printf("Negotiating binary mode with remote host.\r\n");
            tel_enter_binary(3);
        }
    } else {
        if (my_want_state_is_wont(TELOPT_BINARY) &&
                                        my_want_state_is_dont(TELOPT_BINARY)) {
            printf("Already in network ascii mode with remote host.\r\n");
        } else {
            printf("Negotiating network ascii mode with remote host.\r\n");
            tel_leave_binary(3);
        }
    }
    return 1;
}

static int
togrbinary(int val)
{
    donebinarytoggle = 1;

    if (val == -1)
        val = my_want_state_is_do(TELOPT_BINARY) ? 0 : 1;

    if (val == 1) {
        if (my_want_state_is_do(TELOPT_BINARY)) {
            printf("Already receiving in binary mode.\r\n");
        } else {
            printf("Negotiating binary mode on input.\r\n");
            tel_enter_binary(1);
        }
    } else {
        if (my_want_state_is_dont(TELOPT_BINARY)) {
            printf("Already receiving in network ascii mode.\r\n");
        } else {
            printf("Negotiating network ascii mode on input.\r\n");
            tel_leave_binary(1);
        }
    }
    return 1;
}

static int
togxbinary(int val)
{
    donebinarytoggle = 1;

    if (val == -1)
        val = my_want_state_is_will(TELOPT_BINARY) ? 0 : 1;

    if (val == 1) {
        if (my_want_state_is_will(TELOPT_BINARY)) {
            printf("Already transmitting in binary mode.\r\n");
        } else {
            printf("Negotiating binary mode on output.\r\n");
            tel_enter_binary(2);
        }
    } else {
        if (my_want_state_is_wont(TELOPT_BINARY)) {
            printf("Already transmitting in network ascii mode.\r\n");
        } else {
            printf("Negotiating network ascii mode on output.\r\n");
            tel_leave_binary(2);
        }
    }
    return 1;
}


static int togglehelp(int);

struct togglelist {
    char        *name;                  /* name of toggle */
    char        *help;                  /* help message */
    int         (*handler)(int);        /* routine to do actual setting */
    int         *variable;
    char        *actionexplanation;
    int         needconnect;    /* Need to be connected */
};

static struct togglelist Togglelist[] = {
    { "autoflush",
        "flushing of output when sending interrupt characters",
            0,
                &autoflush,
                    "flush output when sending interrupt characters" },
    { "autosynch",
        "automatic sending of interrupt characters in urgent mode",
            0,
                &autosynch,
                    "send interrupt characters in urgent mode" },
    { "autologin",
        "automatic sending of login name",
            0,
                &autologin,
                    "send login name" },
    { "skiprc",
        "don't read ~/.telnetrc file",
            0,
                &skiprc,
                    "skip reading of ~/.telnetrc file" },
    { "binary",
        "sending and receiving of binary data",
            togbinary,
                0,
                    0 },
    { "inbinary",
        "receiving of binary data",
            togrbinary,
                0,
                    0 },
    { "outbinary",
        "sending of binary data",
            togxbinary,
                0,
                    0 },
    { "crlf",
        "sending carriage returns as telnet <CR><LF>",
            togcrlf,
                &crlf,
                    0 },
    { "crmod",
        "mapping of received carriage returns",
            0,
                &crmod,
                    "map carriage return on output" },
    { "localchars",
        "local recognition of certain control characters",
            lclchars,
                &localchars,
                    "recognize certain control characters" },
    { " ", "", 0, 0 },          /* empty line */
    { "netdata",
        "printing of hexadecimal network data (debugging)",
            0,
                &netdata,
                    "print hexadecimal representation of network traffic" },
    { "prettydump",
        "output of \"netdata\" to user readable format (debugging)",
            0,
                &prettydump,
                    "print user readable output for \"netdata\"" },
    { "options",
        "viewing of options processing (debugging)",
            0,
                &showoptions,
                    "show option processing" },
    { "termdata",
        "(debugging) toggle printing of hexadecimal terminal data",
            0,
                &termdata,
                    "print hexadecimal representation of terminal traffic" },
    { "?",
        0,
            togglehelp },
    { "help",
        0,
            togglehelp },
    { 0 }
};

static int
togglehelp(int unused)
{
    struct togglelist *c;

    for (c = Togglelist; c->name; c++) {
        if (c->help) {
            if (*c->help)
                printf("%-15s toggle %s\r\n", c->name, c->help);
            else
                printf("\r\n");
        }
    }
    printf("\r\n");
    printf("%-15s %s\r\n", "?", "display help information");
    return 0;
}

static void
settogglehelp(int set)
{
    struct togglelist *c;

    for (c = Togglelist; c->name; c++) {
        if (c->help) {
            if (*c->help)
                printf("%-15s %s %s\r\n", c->name, set ? "enable" : "disable",
                                                c->help);
            else
                printf("\r\n");
        }
    }
}

#define GETTOGGLE(name) (struct togglelist *) \
                genget(name, (char **) Togglelist, sizeof(struct togglelist))

static int
toggle(int argc, char *argv[])
{
    int retval = 1;
    char *name;
    struct togglelist *c;

    if (argc < 2) {
        fprintf(stderr,
            "Need an argument to 'toggle' command.  'toggle ?' for help.\r\n");
        return 0;
    }
    argc--;
    argv++;
    while (argc--) {
        name = *argv++;
        c = GETTOGGLE(name);
        if (Ambiguous(c)) {
            fprintf(stderr, "'%s': ambiguous argument ('toggle ?' for help).\r\n",
                                        name);
            return 0;
        } else if (c == 0) {
            fprintf(stderr, "'%s': unknown argument ('toggle ?' for help).\r\n",
                                        name);
            return 0;
        } else if (!connected && c->needconnect) {
            printf("?Need to be connected first.\r\n");
            printf("'send ?' for help\r\n");
            return 0;
        } else {
            if (c->variable) {
                *c->variable = !*c->variable;           /* invert it */
                if (c->actionexplanation) {
                    printf("%s %s.\r\n", *c->variable? "Will" : "Won't",
                                                        c->actionexplanation);
                }
            }
            if (c->handler) {
                retval &= (*c->handler)(-1);
            }
        }
    }
    return retval;
}

/*
 * The following perform the "set" command.
 */

struct termios new_tc = { 0 };

struct setlist {
    char *name;                         /* name */
    char *help;                         /* help information */
    void (*handler)(const char *);
    cc_t *charp;                        /* where it is located at */
};

static struct setlist Setlist[] = {
#ifdef  KLUDGELINEMODE
    { "echo",   "character to toggle local echoing on/off", 0, &echoc },
#endif
    { "escape", "character to escape back to telnet command mode", 0, &escape },
    { "rlogin", "rlogin escape character", 0, &rlogin },
    { " ", "" },
    { " ", "The following need 'localchars' to be toggled true", 0, 0 },
    { "flushoutput", "character to cause an Abort Output", 0, &termFlushChar },
    { "interrupt", "character to cause an Interrupt Process", 0, &termIntChar },
    { "quit",   "character to cause an Abort process", 0, &termQuitChar },
    { "eof",    "character to cause an EOF ", 0, &termEofChar },
    { " ", "" },
    { " ", "The following are for local editing in linemode", 0, 0 },
    { "erase",  "character to use to erase a character", 0, &termEraseChar },
    { "kill",   "character to use to erase a line", 0, &termKillChar },
    { "lnext",  "character to use for literal next", 0, &termLiteralNextChar },
    { "susp",   "character to cause a Suspend Process", 0, &termSuspChar },
    { "reprint", "character to use for line reprint", 0, &termRprntChar },
    { "worderase", "character to use to erase a word", 0, &termWerasChar },
    { "start",  "character to use for XON", 0, &termStartChar },
    { "stop",   "character to use for XOFF", 0, &termStopChar },
    { "forw1",  "alternate end of line character", 0, &termForw1Char },
    { "forw2",  "alternate end of line character", 0, &termForw2Char },
    { "ayt",    "alternate AYT character", 0, &termAytChar },
    { 0 }
};

static struct setlist *
getset(char *name)
{
    return (struct setlist *)
                genget(name, (char **) Setlist, sizeof(struct setlist));
}

void
set_escape_char(char *s)
{
        if (rlogin != _POSIX_VDISABLE) {
                rlogin = (s && *s) ? special(s) : _POSIX_VDISABLE;
                printf("Telnet rlogin escape character is '%s'.\r\n",
                                        control(rlogin));
        } else {
                escape = (s && *s) ? special(s) : _POSIX_VDISABLE;
                printf("Telnet escape character is '%s'.\r\n", control(escape));
        }
}

static int
setcmd(int argc, char *argv[])
{
    int value;
    struct setlist *ct;
    struct togglelist *c;

    if (argc < 2 || argc > 3) {
        printf("Format is 'set Name Value'\r\n'set ?' for help.\r\n");
        return 0;
    }
    if ((argc == 2) && (isprefix(argv[1], "?") || isprefix(argv[1], "help"))) {
        for (ct = Setlist; ct->name; ct++)
            printf("%-15s %s\r\n", ct->name, ct->help);
        printf("\r\n");
        settogglehelp(1);
        printf("%-15s %s\r\n", "?", "display help information");
        return 0;
    }

    ct = getset(argv[1]);
    if (ct == 0) {
        c = GETTOGGLE(argv[1]);
        if (c == 0) {
            fprintf(stderr, "'%s': unknown argument ('set ?' for help).\r\n",
                        argv[1]);
            return 0;
        } else if (Ambiguous(c)) {
            fprintf(stderr, "'%s': ambiguous argument ('set ?' for help).\r\n",
                        argv[1]);
            return 0;
        } else if (!connected && c->needconnect) {
            printf("?Need to be connected first.\r\n");
            printf("'send ?' for help\r\n");
            return 0;
        }

        if (c->variable) {
            if ((argc == 2) || (strcmp("on", argv[2]) == 0))
                *c->variable = 1;
            else if (strcmp("off", argv[2]) == 0)
                *c->variable = 0;
            else {
                printf("Format is 'set togglename [on|off]'\r\n'set ?' for help.\r\n");
                return 0;
            }
            if (c->actionexplanation) {
                printf("%s %s.\r\n", *c->variable? "Will" : "Won't",
                                                        c->actionexplanation);
            }
        }
        if (c->handler)
            (*c->handler)(1);
    } else if (argc != 3) {
        printf("Format is 'set Name Value'\r\n'set ?' for help.\r\n");
        return 0;
    } else if (Ambiguous(ct)) {
        fprintf(stderr, "'%s': ambiguous argument ('set ?' for help).\r\n",
                        argv[1]);
        return 0;
    } else if (ct->handler) {
        (*ct->handler)(argv[2]);
        printf("%s set to \"%s\".\r\n", ct->name, (char *)ct->charp);
    } else {
        if (strcmp("off", argv[2])) {
            value = special(argv[2]);
        } else {
            value = _POSIX_VDISABLE;
        }
        *(ct->charp) = (cc_t)value;
        printf("%s character is '%s'.\r\n", ct->name, control(*(ct->charp)));
    }
    slc_check();
    return 1;
}

static int
unsetcmd(int argc, char *argv[])
{
    struct setlist *ct;
    struct togglelist *c;
    char *name;

    if (argc < 2) {
        fprintf(stderr,
            "Need an argument to 'unset' command.  'unset ?' for help.\r\n");
        return 0;
    }
    if (isprefix(argv[1], "?") || isprefix(argv[1], "help")) {
        for (ct = Setlist; ct->name; ct++)
            printf("%-15s %s\r\n", ct->name, ct->help);
        printf("\r\n");
        settogglehelp(0);
        printf("%-15s %s\r\n", "?", "display help information");
        return 0;
    }

    argc--;
    argv++;
    while (argc--) {
        name = *argv++;
        ct = getset(name);
        if (ct == 0) {
            c = GETTOGGLE(name);
            if (c == 0) {
                fprintf(stderr, "'%s': unknown argument ('unset ?' for help).\r\n",
                        name);
                return 0;
            } else if (Ambiguous(c)) {
                fprintf(stderr, "'%s': ambiguous argument ('unset ?' for help).\r\n",
                        name);
                return 0;
            }
            if (c->variable) {
                *c->variable = 0;
                if (c->actionexplanation) {
                    printf("%s %s.\r\n", *c->variable? "Will" : "Won't",
                                                        c->actionexplanation);
                }
            }
            if (c->handler)
                (*c->handler)(0);
        } else if (Ambiguous(ct)) {
            fprintf(stderr, "'%s': ambiguous argument ('unset ?' for help).\r\n",
                        name);
            return 0;
        } else if (ct->handler) {
            (*ct->handler)(NULL);
            printf("%s reset to \"%s\".\r\n", ct->name, (char *)ct->charp);
        } else {
            *(ct->charp) = _POSIX_VDISABLE;
            printf("%s character is '%s'.\r\n", ct->name, control(*(ct->charp)));
        }
    }
    return 1;
}

/*
 * The following are the data structures and routines for the
 * 'mode' command.
 */
#ifdef  KLUDGELINEMODE
static int
dokludgemode(int unused)
{
    kludgelinemode = 1;
    send_wont(TELOPT_LINEMODE, 1);
    send_dont(TELOPT_SGA, 1);
    send_dont(TELOPT_ECHO, 1);
    return 1;
}
#endif

static int
dolinemode(int unused)
{
#ifdef  KLUDGELINEMODE
    if (kludgelinemode)
        send_dont(TELOPT_SGA, 1);
#endif
    send_will(TELOPT_LINEMODE, 1);
    send_dont(TELOPT_ECHO, 1);
    return 1;
}

static int
docharmode(int unused)
{
#ifdef  KLUDGELINEMODE
    if (kludgelinemode)
        send_do(TELOPT_SGA, 1);
    else
#endif
    send_wont(TELOPT_LINEMODE, 1);
    send_do(TELOPT_ECHO, 1);
    return 1;
}

static int
dolmmode(int bit, int on)
{
    unsigned char c;

    if (my_want_state_is_wont(TELOPT_LINEMODE)) {
        printf("?Need to have LINEMODE option enabled first.\r\n");
        printf("'mode ?' for help.\r\n");
        return 0;
    }

    if (on)
        c = (linemode | bit);
    else
        c = (linemode & ~bit);
    lm_mode(&c, 1, 1);
    return 1;
}

int
tn_setmode(int bit)
{
    return dolmmode(bit, 1);
}

int
tn_clearmode(int bit)
{
    return dolmmode(bit, 0);
}

struct modelist {
        char    *name;          /* command name */
        char    *help;          /* help string */
        int     (*handler)(int);/* routine which executes command */
        int     needconnect;    /* Do we need to be connected to execute? */
        int     arg1;
};

static int modehelp(int);

static struct modelist ModeList[] = {
    { "character", "Disable LINEMODE option",   docharmode, 1 },
#ifdef  KLUDGELINEMODE
    { "",       "(or disable obsolete line-by-line mode)", 0 },
#endif
    { "line",   "Enable LINEMODE option",       dolinemode, 1 },
#ifdef  KLUDGELINEMODE
    { "",       "(or enable obsolete line-by-line mode)", 0 },
#endif
    { "", "", 0 },
    { "",       "These require the LINEMODE option to be enabled", 0 },
    { "isig",   "Enable signal trapping",       tn_setmode, 1, MODE_TRAPSIG },
    { "+isig",  0,                              tn_setmode, 1, MODE_TRAPSIG },
    { "-isig",  "Disable signal trapping",      tn_clearmode, 1, MODE_TRAPSIG },
    { "edit",   "Enable character editing",     tn_setmode, 1, MODE_EDIT },
    { "+edit",  0,                              tn_setmode, 1, MODE_EDIT },
    { "-edit",  "Disable character editing",    tn_clearmode, 1, MODE_EDIT },
    { "softtabs", "Enable tab expansion",       tn_setmode, 1, MODE_SOFT_TAB },
    { "+softtabs", 0,                           tn_setmode, 1, MODE_SOFT_TAB },
    { "-softtabs", "Disable character editing", tn_clearmode, 1, MODE_SOFT_TAB },
    { "litecho", "Enable literal character echo", tn_setmode, 1, MODE_LIT_ECHO },
    { "+litecho", 0,                            tn_setmode, 1, MODE_LIT_ECHO },
    { "-litecho", "Disable literal character echo", tn_clearmode, 1, MODE_LIT_ECHO },
    { "help",   0,                              modehelp, 0 },
#ifdef  KLUDGELINEMODE
    { "kludgeline", 0,                          dokludgemode, 1 },
#endif
    { "", "", 0 },
    { "?",      "Print help information",       modehelp, 0 },
    { 0 },
};

static int
modehelp(int unused)
{
    struct modelist *mt;

    printf("format is:  'mode Mode', where 'Mode' is one of:\r\n\r\n");
    for (mt = ModeList; mt->name; mt++) {
        if (mt->help) {
            if (*mt->help)
                printf("%-15s %s\r\n", mt->name, mt->help);
            else
                printf("\r\n");
        }
    }
    return 0;
}

#define GETMODECMD(name) (struct modelist *) \
                genget(name, (char **) ModeList, sizeof(struct modelist))

static int
modecmd(int argc, char *argv[])
{
    struct modelist *mt;

    if (argc != 2) {
        printf("'mode' command requires an argument\r\n");
        printf("'mode ?' for help.\r\n");
    } else if ((mt = GETMODECMD(argv[1])) == 0) {
        fprintf(stderr, "Unknown mode '%s' ('mode ?' for help).\r\n", argv[1]);
    } else if (Ambiguous(mt)) {
        fprintf(stderr, "Ambiguous mode '%s' ('mode ?' for help).\r\n", argv[1]);
    } else if (mt->needconnect && !connected) {
        printf("?Need to be connected first.\r\n");
        printf("'mode ?' for help.\r\n");
    } else if (mt->handler) {
        return (*mt->handler)(mt->arg1);
    }
    return 0;
}

/*
 * The following data structures and routines implement the
 * "display" command.
 */

static int
display(int argc, char *argv[])
{
    struct togglelist *tl;
    struct setlist *sl;

#define dotog(tl)       if (tl->variable && tl->actionexplanation) { \
                            if (*tl->variable) { \
                                printf("will"); \
                            } else { \
                                printf("won't"); \
                            } \
                            printf(" %s.\r\n", tl->actionexplanation); \
                        }

#define doset(sl)   if (sl->name && *sl->name != ' ') { \
                        if (sl->handler == 0) \
                            printf("%-15s [%s]\r\n", sl->name, control(*sl->charp)); \
                        else \
                            printf("%-15s \"%s\"\r\n", sl->name, (char *)sl->charp); \
                    }

    if (argc == 1) {
        for (tl = Togglelist; tl->name; tl++) {
            dotog(tl);
        }
        printf("\r\n");
        for (sl = Setlist; sl->name; sl++) {
            doset(sl);
        }
    } else {
        int i;

        for (i = 1; i < argc; i++) {
            sl = getset(argv[i]);
            tl = GETTOGGLE(argv[i]);
            if (Ambiguous(sl) || Ambiguous(tl)) {
                printf("?Ambiguous argument '%s'.\r\n", argv[i]);
                return 0;
            } else if (!sl && !tl) {
                printf("?Unknown argument '%s'.\r\n", argv[i]);
                return 0;
            } else {
                if (tl) {
                    dotog(tl);
                }
                if (sl) {
                    doset(sl);
                }
            }
        }
    }
/*@*/optionstatus();
    return 1;
#undef  doset
#undef  dotog
}

/*
 * The following are the data structures, and many of the routines,
 * relating to command processing.
 */

/*
 * Set the escape character.
 */
static int
setescape(int argc, char *argv[])
{
        char *arg;
        char buf[50];

        printf(
            "Deprecated usage - please use 'set escape%s%s' in the future.\r\n",
                                (argc > 2)? " ":"", (argc > 2)? argv[1]: "");
        if (argc > 2)
                arg = argv[1];
        else {
                printf("new escape character: ");
                (void) fgets(buf, sizeof(buf), stdin);
                arg = buf;
        }
        if (arg[0] != '\0')
                escape = arg[0];
        printf("Escape character is '%s'.\r\n", control(escape));
        (void) fflush(stdout);
        return 1;
}

static int
togcrmod(int unused1, char *unused2[])
{
    crmod = !crmod;
    printf("Deprecated usage - please use 'toggle crmod' in the future.\r\n");
    printf("%s map carriage return on output.\r\n", crmod ? "Will" : "Won't");
    (void) fflush(stdout);
    return 1;
}

int
telnetsuspend(int unused1, char *unused2[])
{
    setcommandmode();
    {
        long oldrows, oldcols, newrows, newcols, err;

        err = (TerminalWindowSize(&oldrows, &oldcols) == 0) ? 1 : 0;
        (void) kill(0, SIGTSTP);
        /*
         * If we didn't get the window size before the SUSPEND, but we
         * can get them now (?), then send the NAWS to make sure that
         * we are set up for the right window size.
         */
        if (TerminalWindowSize(&newrows, &newcols) && connected &&
            (err || ((oldrows != newrows) || (oldcols != newcols)))) {
                sendnaws();
        }
    }
    /* reget parameters in case they were changed */
    TerminalSaveState();
    setconnmode(0);
    return 1;
}

static void
close_connection(void)
{
        if (connected) {
                (void) shutdown(net, SHUT_RDWR);
                printf("Connection closed.\r\n");
                (void)close(net);
                connected = 0;
                resettermname = 1;
                /* reset options */
                tninit();
        }
}

static int
bye(int argc, char *argv[])
{
        close_connection();
        longjmp(toplevel, 1);
}

void
quit(void)
{
        close_connection();
        Exit(0);
}

static int
quitcmd(int unused1, char *unused2[])
{
        quit();
}

static int
logout(int unused1, char *unused2[])
{
        send_do(TELOPT_LOGOUT, 1);
        (void) netflush();
        return 1;
}


/*
 * The SLC command.
 */

struct slclist {
        char    *name;
        char    *help;
        void    (*handler)(int);
        int     arg;
};

static void slc_help(int);

struct slclist SlcList[] = {
    { "export", "Use local special character definitions",
                                                slc_mode_export,        0 },
    { "import", "Use remote special character definitions",
                                                slc_mode_import,        1 },
    { "check",  "Verify remote special character definitions",
                                                slc_mode_import,        0 },
    { "help",   0,                              slc_help,               0 },
    { "?",      "Print help information",       slc_help,               0 },
    { 0 },
};

static void
slc_help(int unused)
{
    struct slclist *c;

    for (c = SlcList; c->name; c++) {
        if (c->help) {
            if (*c->help)
                printf("%-15s %s\r\n", c->name, c->help);
            else
                printf("\r\n");
        }
    }
}

static struct slclist *
getslc(char *name)
{
    return (struct slclist *)
                genget(name, (char **) SlcList, sizeof(struct slclist));
}

static int
slccmd(int argc, char *argv[])
{
    struct slclist *c;

    if (argc != 2) {
        fprintf(stderr,
            "Need an argument to 'slc' command.  'slc ?' for help.\r\n");
        return 0;
    }
    c = getslc(argv[1]);
    if (c == 0) {
        fprintf(stderr, "'%s': unknown argument ('slc ?' for help).\r\n",
                                argv[1]);
        return 0;
    }
    if (Ambiguous(c)) {
        fprintf(stderr, "'%s': ambiguous argument ('slc ?' for help).\r\n",
                                argv[1]);
        return 0;
    }
    (*c->handler)(c->arg);
    slcstate();
    return 1;
}

/*
 * The ENVIRON command.
 */

struct envlist {
        char    *name;
        char    *help;
        void    (*handler)();
        int     narg;
};

static void     env_help(void);
static void     env_undefine(const char *);
static void     env_export(const char *);
static void     env_unexport(const char *);
static void     env_send(const char *);
static void     env_list(void);
static struct env_lst *env_find(const char *var);

struct envlist EnvList[] = {
    { "define", "Define an environment variable",
                                                (void (*)())env_define, 2 },
    { "undefine", "Undefine an environment variable",
                                                env_undefine,   1 },
    { "export", "Mark an environment variable for automatic export",
                                                env_export,     1 },
    { "unexport", "Don't mark an environment variable for automatic export",
                                                env_unexport,   1 },
    { "send",   "Send an environment variable", env_send,       1 },
    { "list",   "List the current environment variables",
                                                env_list,       0 },
    { "help",   0,                              env_help,               0 },
    { "?",      "Print help information",       env_help,               0 },
    { 0 },
};

static void
env_help(void)
{
    struct envlist *c;

    for (c = EnvList; c->name; c++) {
        if (c->help) {
            if (*c->help)
                printf("%-15s %s\r\n", c->name, c->help);
            else
                printf("\r\n");
        }
    }
}

static struct envlist *
getenvcmd(char *name)
{
    return (struct envlist *)
                genget(name, (char **) EnvList, sizeof(struct envlist));
}

static int
env_cmd(int argc, char *argv[])
{
    struct envlist *c;

    if (argc < 2) {
        fprintf(stderr,
            "Need an argument to 'environ' command.  'environ ?' for help.\r\n");
        return 0;
    }
    c = getenvcmd(argv[1]);
    if (c == 0) {
        fprintf(stderr, "'%s': unknown argument ('environ ?' for help).\r\n",
                                argv[1]);
        return 0;
    }
    if (Ambiguous(c)) {
        fprintf(stderr, "'%s': ambiguous argument ('environ ?' for help).\r\n",
                                argv[1]);
        return 0;
    }
    if (c->narg + 2 != argc) {
        fprintf(stderr,
            "Need %s%d argument%s to 'environ %s' command.  'environ ?' for help.\r\n",
                c->narg < argc + 2 ? "only " : "",
                c->narg, c->narg == 1 ? "" : "s", c->name);
        return 0;
    }
    (*c->handler)(argv[2], argv[3]);
    return 1;
}

struct env_lst {
        struct env_lst *next;   /* pointer to next structure */
        struct env_lst *prev;   /* pointer to previous structure */
        char *var;              /* pointer to variable name */
        char *value;            /* pointer to variable value */
        int export;             /* 1 -> export with default list of variables */
        int welldefined;        /* A well defined variable */
};

struct env_lst envlisthead;

static struct env_lst *
env_find(const char *var)
{
        struct env_lst *ep;

        for (ep = envlisthead.next; ep; ep = ep->next) {
                if (strcmp(ep->var, var) == 0)
                        return(ep);
        }
        return(NULL);
}

void
env_init(void)
{
        extern char **environ;
        char **epp, *cp;
        struct env_lst *ep;

        for (epp = environ; *epp; epp++) {
                if ((cp = strchr(*epp, '='))) {
                        *cp = '\0';
                        ep = env_define(*epp, cp+1);
                        ep->export = 0;
                        *cp = '=';
                }
        }
        /*
         * Special case for DISPLAY variable.  If it is ":0.0" or
         * "unix:0.0", we have to get rid of "unix" and insert our
         * hostname.
         */
        if ((ep = env_find("DISPLAY"))
            && ((*ep->value == ':')
                || (strncmp(ep->value, "unix:", 5) == 0))) {
                char hbuf[HOST_NAME_MAX+1];
                char *cp2 = strchr(ep->value, ':');

                gethostname(hbuf, sizeof hbuf);

                if (asprintf (&cp, "%s%s", hbuf, cp2) == -1)
                        err(1, "asprintf");

                free(ep->value);
                ep->value = cp;
        }
        /*
         * If USER is not defined, but LOGNAME is, then add
         * USER with the value from LOGNAME.  By default, we
         * don't export the USER variable.
         */
        if ((env_find("USER") == NULL) && (ep = env_find("LOGNAME"))) {
                env_define("USER", ep->value);
                env_unexport("USER");
        }
        env_export("DISPLAY");
        env_export("PRINTER");
        env_export("XAUTHORITY");
}

struct env_lst *
env_define(const char *var, const char *value)
{
        struct env_lst *ep;

        if ((ep = env_find(var))) {
                free(ep->var);
                free(ep->value);
        } else {
                if ((ep = malloc(sizeof(struct env_lst))) == NULL)
                        err(1, "malloc");
                ep->next = envlisthead.next;
                envlisthead.next = ep;
                ep->prev = &envlisthead;
                if (ep->next)
                        ep->next->prev = ep;
        }
        ep->welldefined = opt_welldefined(var);
        ep->export = 1;
        if ((ep->var = strdup(var)) == NULL)
                err(1, "strdup");
        if ((ep->value = strdup(value)) == NULL)
                err(1, "strdup");
        return(ep);
}

static void
env_undefine(const char *var)
{
        struct env_lst *ep;

        if ((ep = env_find(var))) {
                ep->prev->next = ep->next;
                if (ep->next)
                        ep->next->prev = ep->prev;
                free(ep->var);
                free(ep->value);
                free(ep);
        }
}

static void
env_export(const char *var)
{
        struct env_lst *ep;

        if ((ep = env_find(var)))
                ep->export = 1;
}

static void
env_unexport(const char *var)
{
        struct env_lst *ep;

        if ((ep = env_find(var)) != NULL)
                ep->export = 0;
}

static void
env_send(const char *var)
{
        struct env_lst *ep;

        if (my_state_is_wont(TELOPT_NEW_ENVIRON)
                ) {
                fprintf(stderr,
                    "Cannot send '%s': Telnet ENVIRON option not enabled\r\n",
                                                                        var);
                return;
        }
        ep = env_find(var);
        if (ep == 0) {
                fprintf(stderr, "Cannot send '%s': variable not defined\r\n",
                                                                        var);
                return;
        }
        env_opt_start_info();
        env_opt_add(ep->var);
        env_opt_end(0);
}

static void
env_list(void)
{
        struct env_lst *ep;

        for (ep = envlisthead.next; ep; ep = ep->next) {
                printf("%c %-20s %s\r\n", ep->export ? '*' : ' ',
                                        ep->var, ep->value);
        }
}

char *
env_default(int init, int welldefined)
{
        static struct env_lst *nep = NULL;

        if (init) {
                nep = &envlisthead;
                return NULL;
        }
        if (nep) {
                while ((nep = nep->next)) {
                        if (nep->export && (nep->welldefined == welldefined))
                                return(nep->var);
                }
        }
        return(NULL);
}

char *
env_getvalue(const char *var, int exported_only)
{
        struct env_lst *ep;

        if ((ep = env_find(var)) && (!exported_only || ep->export))
                return(ep->value);
        return(NULL);
}

static void
connection_status(int local_only)
{
        if (!connected)
                printf("No connection.\r\n");
        else {
                printf("Connected to %s.\r\n", hostname);
                if (!local_only) {
                        int mode = getconnmode();

                        printf("Operating ");
                        if (my_want_state_is_will(TELOPT_LINEMODE)) {
                                printf("with LINEMODE option\r\n"
                                    "%s line editing\r\n"
                                    "%s catching of signals\r\n",
                                    (mode & MODE_EDIT) ? "Local" : "No",
                                    (mode & MODE_TRAPSIG) ? "Local" : "No");
                                slcstate();
#ifdef  KLUDGELINEMODE
                        } else if (kludgelinemode &&
                            my_want_state_is_dont(TELOPT_SGA)) {
                                printf("in obsolete linemode\r\n");
#endif
                        } else {
                                printf("in single character mode\r\n");
                                if (localchars)
                                        printf("Catching signals locally\r\n");
                        }

                        printf("%s character echo\r\n",
                            (mode & MODE_ECHO) ? "Local" : "Remote");
                        if (my_want_state_is_will(TELOPT_LFLOW))
                                printf("%s flow control\r\n",
                                    (mode & MODE_FLOW) ? "Local" : "No");
                }
        }
        printf("Escape character is '%s'.\r\n", control(escape));
        (void) fflush(stdout);
}

/*
 * Print status about the connection.
 */
static int
status(int argc, char *argv[])
{
        connection_status(0);
        return 1;
}

/*
 * Function that gets called when SIGINFO is received.
 */
void
ayt_status(int sig)
{
        connection_status(1);
}

static Command *getcmd(char *name);

static void
cmdrc(char *m1, char *m2)
{
    static char rcname[128];
    Command *c;
    FILE *rcfile;
    int gotmachine = 0;
    int l1 = strlen(m1);
    int l2 = strlen(m2);
    char m1save[HOST_NAME_MAX+1];

    if (skiprc)
        return;

    strlcpy(m1save, m1, sizeof(m1save));
    m1 = m1save;

    if (rcname[0] == 0) {
        char *home = getenv("HOME");

        if (home == NULL || *home == '\0')
            return;
        snprintf (rcname, sizeof(rcname), "%s/.telnetrc",
                  home ? home : "");
    }

    if ((rcfile = fopen(rcname, "r")) == 0) {
        return;
    }

    for (;;) {
        if (fgets(line, sizeof(line), rcfile) == NULL)
            break;
        if (line[0] == 0)
            break;
        if (line[0] == '#')
            continue;
        if (gotmachine) {
            if (!isspace((unsigned char)line[0]))
                gotmachine = 0;
        }
        if (gotmachine == 0) {
            if (isspace((unsigned char)line[0]))
                continue;
            if (strncasecmp(line, m1, l1) == 0)
                strncpy(line, &line[l1], sizeof(line) - l1);
            else if (strncasecmp(line, m2, l2) == 0)
                strncpy(line, &line[l2], sizeof(line) - l2);
            else if (strncasecmp(line, "DEFAULT", 7) == 0)
                strncpy(line, &line[7], sizeof(line) - 7);
            else
                continue;
            if (line[0] != ' ' && line[0] != '\t' && line[0] != '\n')
                continue;
            gotmachine = 1;
        }
        if (makeargv())
            continue;
        if (margv[0] == 0)
            continue;
        c = getcmd(margv[0]);
        if (Ambiguous(c)) {
            printf("?Ambiguous command: %s\r\n", margv[0]);
            continue;
        }
        if (c == 0) {
            printf("?Invalid command: %s\r\n", margv[0]);
            continue;
        }
        /*
         * This should never happen...
         */
        if (c->needconnect && !connected) {
            printf("?Need to be connected first for %s.\r\n", margv[0]);
            continue;
        }
        (*c->handler)(margc, margv);
    }
    fclose(rcfile);
}

int
tn(int argc, char *argv[])
{
    struct addrinfo hints, *res, *res0;
    char *cmd, *hostp = 0, *portp = 0, *user = 0, *aliasp = 0;
    int error, retry;
    const int niflags = NI_NUMERICHOST, tos = IPTOS_LOWDELAY;

    if (connected) {
        printf("?Already connected to %s\r\n", hostname);
        return 0;
    }
    if (connections) {
        printf("Repeated connections not supported\r\n");
        return 0;
    }
    if (argc < 2) {
        strlcpy(line, "open ", sizeof(line));
        printf("(to) ");
        (void) fgets(&line[strlen(line)], sizeof(line) - strlen(line), stdin);
        if (makeargv())
            return 0;
        argc = margc;
        argv = margv;
    }
    cmd = *argv;
    --argc; ++argv;
    while (argc) {
        if (strcmp(*argv, "help") == 0 || isprefix(*argv, "?"))
            goto usage;
        if (strcmp(*argv, "-l") == 0) {
            --argc; ++argv;
            if (argc == 0)
                goto usage;
            if ((user = strdup(*argv++)) == NULL)
                err(1, "strdup");
            --argc;
            continue;
        }
        if (strcmp(*argv, "-b") == 0) {
            --argc; ++argv;
            if (argc == 0)
                goto usage;
            aliasp = *argv++;
            --argc;
            continue;
        }
        if (strcmp(*argv, "-a") == 0) {
            --argc; ++argv;
            autologin = 1;
            continue;
        }
        if (hostp == 0) {
            hostp = *argv++;
            --argc;
            continue;
        }
        if (portp == 0) {
            portp = *argv++;
            --argc;
            continue;
        }
    usage:
        printf("usage: %s [-a] [-b hostalias] [-l user] host-name [port]\r\n", cmd);
        return 0;
    }
    if (hostp == 0)
        goto usage;

    hostname = hostp;
    memset(&hints, 0, sizeof(hints));
    hints.ai_family = family;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_flags = AI_CANONNAME;
    if (portp == NULL) {
        portp = "telnet";
        telnetport = 1;
    } else if (*portp == '-') {
        portp++;
        telnetport = 1;
    } else
        telnetport = 0;
    error = getaddrinfo(hostp, portp, &hints, &res0);
    if (error) {
        if (error == EAI_SERVICE)
            warnx("%s: bad port", portp);
        else
            warnx("%s: %s", hostp, gai_strerror(error));
        return 0;
    }

    net = -1;
    retry = 0;
    for (res = res0; res; res = res->ai_next) {
        if (1 /* retry */) {
            char hbuf[NI_MAXHOST];

            if (getnameinfo(res->ai_addr, res->ai_addrlen, hbuf, sizeof(hbuf),
                    NULL, 0, niflags) != 0) {
                strlcpy(hbuf, "(invalid)", sizeof(hbuf));
            }
            printf("Trying %s...\r\n", hbuf);
        }
        net = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
        if (net == -1)
            continue;

        if (aliasp) {
            struct addrinfo ahints, *ares;

            memset(&ahints, 0, sizeof(ahints));
            ahints.ai_family = family;
            ahints.ai_socktype = SOCK_STREAM;
            ahints.ai_flags = AI_PASSIVE;
            error = getaddrinfo(aliasp, "0", &ahints, &ares);
            if (error) {
                warn("%s: %s", aliasp, gai_strerror(error));
                close(net);
                net = -1;
                continue;
            }
            if (bind(net, ares->ai_addr, ares->ai_addrlen) == -1) {
                perror(aliasp);
                (void) close(net);   /* dump descriptor */
                net = -1;
                freeaddrinfo(ares);
                continue;
            }
            freeaddrinfo(ares);
        }

        switch (res->ai_family) {
        case AF_INET:
                if (setsockopt(net, IPPROTO_IP, IP_TOS, &tos, sizeof(tos)) == -1
                    && errno != ENOPROTOOPT)
                        perror("telnet: setsockopt (IP_TOS) (ignored)");
                break;
        case AF_INET6:
                if (setsockopt(net, IPPROTO_IPV6, IPV6_TCLASS, &tos,
                    sizeof(tos)) == -1 && errno != ENOPROTOOPT)
                        perror("telnet: setsockopt (IPV6_TCLASS) (ignored)");
                break;
        }

        if (connect(net, res->ai_addr, res->ai_addrlen) == -1) {
            char hbuf[NI_MAXHOST];

            if (getnameinfo(res->ai_addr, res->ai_addrlen, hbuf, sizeof(hbuf),
                    NULL, 0, niflags) != 0) {
                strlcpy(hbuf, "(invalid)", sizeof(hbuf));
            }
            fprintf(stderr, "telnet: connect to address %s: %s\n", hbuf,
                strerror(errno));

            close(net);
            net = -1;
            retry++;
            continue;
        }

        connected++;
        break;
    }
    freeaddrinfo(res0);
    if (net < 0) {
        return 0;
    }
    cmdrc(hostp, hostname);
    if (autologin && user == NULL) {
        struct passwd *pw;

        user = getlogin();
        if (user == NULL ||
            (pw = getpwnam(user)) == NULL || pw->pw_uid != getuid()) {
                if ((pw = getpwuid(getuid())) != NULL)
                        user = pw->pw_name;
                else
                        user = NULL;
        }
    }
    if (user) {
        env_define("USER", user);
        env_export("USER");
    }
    connection_status(1);
    if (setjmp(peerdied) == 0)
        telnet(user);
    (void)close(net);
    ExitString("Connection closed by foreign host.\r\n",1);
}

#define HELPINDENT (sizeof ("connect"))

static char
        openhelp[] =    "connect to a site",
        closehelp[] =   "close current connection",
        logouthelp[] =  "forcibly logout remote user and close the connection",
        quithelp[] =    "exit telnet",
        statushelp[] =  "print status information",
        helphelp[] =    "print help information",
        sendhelp[] =    "transmit special characters ('send ?' for more)",
        sethelp[] =     "set operating parameters ('set ?' for more)",
        unsethelp[] =   "unset operating parameters ('unset ?' for more)",
        togglestring[] ="toggle operating parameters ('toggle ?' for more)",
        slchelp[] =     "change state of special characters ('slc ?' for more)",
        displayhelp[] = "display operating parameters",
        zhelp[] =       "suspend telnet",
        envhelp[] =     "change environment variables ('environ ?' for more)",
        modestring[] = "try to enter line or character mode ('mode ?' for more)";

static int      help(int, char**);

static Command cmdtab[] = {
        { "close",      closehelp,      bye,            1 },
        { "logout",     logouthelp,     logout,         1 },
        { "display",    displayhelp,    display,        0 },
        { "mode",       modestring,     modecmd,        0 },
        { "open",       openhelp,       tn,             0 },
        { "quit",       quithelp,       quitcmd,        0 },
        { "send",       sendhelp,       sendcmd,        0 },
        { "set",        sethelp,        setcmd,         0 },
        { "unset",      unsethelp,      unsetcmd,       0 },
        { "status",     statushelp,     status,         0 },
        { "toggle",     togglestring,   toggle,         0 },
        { "slc",        slchelp,        slccmd,         0 },

        { "z",          zhelp,          telnetsuspend,  0 },
        { "environ",    envhelp,        env_cmd,        0 },
        { "?",          helphelp,       help,           0 },
        { 0,            0,              0,              0 }
};

static char     crmodhelp[] =   "deprecated command -- use 'toggle crmod' instead";
static char     escapehelp[] =  "deprecated command -- use 'set escape' instead";

static Command cmdtab2[] = {
        { "help",       0,              help,           0 },
        { "escape",     escapehelp,     setescape,      0 },
        { "crmod",      crmodhelp,      togcrmod,       0 },
        { 0,            0,              0,              0 }
};


static Command *
getcmd(char *name)
{
    Command *cm;

    if ((cm = (Command *) genget(name, (char **) cmdtab, sizeof(Command))))
        return cm;
    return (Command *) genget(name, (char **) cmdtab2, sizeof(Command));
}

void
command(int top, char *tbuf, int cnt)
{
    Command *c;

    setcommandmode();
    if (!top) {
        putchar('\n');
    } else {
        (void) signal(SIGINT, SIG_DFL);
        (void) signal(SIGQUIT, SIG_DFL);
    }
    for (;;) {
        if (rlogin == _POSIX_VDISABLE)
                printf("%s> ", prompt);
        if (tbuf) {
            char *cp;
            cp = line;
            while (cnt > 0 && (*cp++ = *tbuf++) != '\n')
                cnt--;
            tbuf = 0;
            if (cp == line || *--cp != '\n' || cp == line)
                goto getline;
            *cp = '\0';
            if (rlogin == _POSIX_VDISABLE)
                printf("%s\r\n", line);
        } else {
        getline:
            if (rlogin != _POSIX_VDISABLE)
                printf("%s> ", prompt);
            if (fgets(line, sizeof(line), stdin) == NULL) {
                if (feof(stdin) || ferror(stdin))
                    quit();
                break;
            }
        }
        if (line[0] == 0)
            break;
        if (makeargv())
            break;
        if (margv[0] == 0) {
            break;
        }
        c = getcmd(margv[0]);
        if (Ambiguous(c)) {
            printf("?Ambiguous command\r\n");
            continue;
        }
        if (c == 0) {
            printf("?Invalid command\r\n");
            continue;
        }
        if (c->needconnect && !connected) {
            printf("?Need to be connected first.\r\n");
            continue;
        }
        if ((*c->handler)(margc, margv)) {
            break;
        }
    }
    if (!top) {
        if (!connected)
            longjmp(toplevel, 1);
        setconnmode(0);
    }
}

/*
 * Help command.
 */
static int
help(int argc, char *argv[])
{
        Command *c;

        if (argc == 1) {
                printf("Commands may be abbreviated.  Commands are:\r\n\r\n");
                for (c = cmdtab; c->name; c++)
                        if (c->help) {
                                printf("%-*s\t%s\r\n", (int)HELPINDENT, c->name,
                                                                    c->help);
                        }
                return 0;
        }
        while (--argc > 0) {
                char *arg;
                arg = *++argv;
                c = getcmd(arg);
                if (Ambiguous(c))
                        printf("?Ambiguous help command %s\r\n", arg);
                else if (c == NULL)
                        printf("?Invalid help command %s\r\n", arg);
                else
                        printf("%s\r\n", c->help);
        }
        return 0;
}