usr.bin/tftp/main.c

	main.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2002 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*  Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T */
/*    All Rights Reserved   */

/*
 * University Copyright- Copyright (c) 1982, 1986, 1988
 * The Regents of the University of California
 * All Rights Reserved
 *
 * University Acknowledgment- Portions of this document are derived from
 * software developed by the University of California, Berkeley, and its
 * contributors.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

/*
 * TFTP User Program -- Command Interface.
 */
#include <sys/types.h>
#include <sys/socket.h>

#include <arpa/inet.h>

#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <ctype.h>
#include <netdb.h>
#include <fcntl.h>
#include <string.h>
#include <limits.h>

#include "tftpcommon.h"
#include "tftpprivate.h"

#define NELEM(a)    (sizeof (a) / sizeof ((a)[0]))

#define TIMEOUT     5       /* secs between rexmt's */

struct sockaddr_in6 sin6;
int         f;
int         maxtimeout = 5 * TIMEOUT;
int         verbose;
int         trace;
int         srexmtval;
int         blksize;
int         rexmtval = TIMEOUT;
int         tsize_opt;
jmp_buf         toplevel;

static int          default_port, port;
static int          connected;
static char         mode[32];
static char         line[200];
static char         *prompt = "tftp";
static char         hostname[MAXHOSTNAMELEN];

static void     intr(int);
static void     quit(int, char **);
static void     help(int, char **);
static void     setverbose(int, char **);
static void     settrace(int, char **);
static void     status(int, char **);
static void     get(int, char **);
static void     put(int, char **);
static void     setpeer(int, char **);
static void     modecmd(int, char **);
static void     setrexmt(int, char **);
static void     settimeout(int, char **);
static void     setbinary(int, char **);
static void     setascii(int, char **);
static void     setblksize(int, char **);
static void     setsrexmt(int, char **);
static void     settsize(int, char **);
static void     setmode(char *);
static void     putusage(char *);
static void     getusage(char *);
static char     *finddelimiter(char *);
static char     *removebrackets(char *);
static int      prompt_for_arg(char *, int, char *);
static struct cmd   *getcmd(char *);
static char     *tail(char *);
static void     command(int);
static void     makeargv(int *, char ***);

#define HELPINDENT (sizeof ("connect"))

struct cmd {
    char    *name;
    char    *help;
    void    (*handler)(int, char **);
};

static char vhelp[] =   "toggle verbose mode";
static char thelp[] =   "toggle packet tracing";
static char chelp[] =   "connect to remote tftp";
static char qhelp[] =   "exit tftp";
static char hhelp[] =   "print help information";
static char shelp[] =   "send file";
static char rhelp[] =   "receive file";
static char mhelp[] =   "set file transfer mode";
static char sthelp[] =  "show current status";
static char xhelp[] =   "set per-packet retransmission timeout";
static char ihelp[] =   "set total retransmission timeout";
static char ashelp[] =  "set mode to netascii";
static char bnhelp[] =  "set mode to octet";
static char bshelp[] =  "set transfer blocksize to negotiate with the "
                "server";
static char srhelp[] =  "set preferred per-packet retransmission "
                "timeout for server";
static char tshelp[] =  "toggle sending the transfer size option to "
                "the server";

static struct cmd   cmdtab[] = {
    { "connect",    chelp,      setpeer },
    { "mode",   mhelp,      modecmd },
    { "put",    shelp,      put },
    { "get",    rhelp,      get },
    { "quit",   qhelp,      quit },
    { "verbose",    vhelp,      setverbose },
    { "trace",  thelp,      settrace },
    { "status", sthelp,     status },
    { "binary", bnhelp,     setbinary },
    { "ascii",  ashelp,     setascii },
    { "rexmt",  xhelp,      setrexmt },
    { "timeout",    ihelp,      settimeout },
    { "blksize",    bshelp,     setblksize },
    { "srexmt", srhelp,     setsrexmt },
    { "tsize",  tshelp,     settsize },
    { "?",      hhelp,      help },
    { NULL }
};

#define AMBIGCMD    (&cmdtab[NELEM(cmdtab)])

int
main(int argc, char **argv)
{
    struct servent *sp;
    struct sockaddr_in6 sin6;
    int top;

    sp = getservbyname("tftp", "udp");
    default_port = (sp != NULL) ? sp->s_port : htons(IPPORT_TFTP);
    port = default_port;

    f = socket(AF_INET6, SOCK_DGRAM, 0);
    if (f < 0) {
        perror("tftp: socket");
        exit(3);
    }

    (void) memset(&sin6, 0, sizeof (sin6));
    sin6.sin6_family = AF_INET6;
    if (bind(f, (struct sockaddr *)&sin6, sizeof (sin6)) < 0) {
        perror("tftp: bind");
        exit(1);
    }

    (void) strlcpy(mode, "netascii", sizeof (mode));
    (void) signal(SIGINT, intr);
    if (argc > 1) {
        if (setjmp(toplevel) != 0)
            exit(0);
        setpeer(argc, argv);
    }

    top = (setjmp(toplevel) == 0);
    for (;;)
        command(top);

    /*NOTREACHED*/
    return (0);
}

/* Prompt for command argument, add to buffer with space separator */
static int
prompt_for_arg(char *buffer, int buffer_size, char *prompt)
{
    int ch;

    if (strlcat(buffer, " ", buffer_size) >= buffer_size) {
        (void) fputs("?Line too long\n", stderr);
        return (-1);
    }
    (void) printf("(%s) ", prompt);
    if (fgets(buffer + strlen(buffer), buffer_size - strlen(buffer),
        stdin) == NULL) {
        return (-1);
    }
    /* Flush what didn't fit in the buffer */
    if (buffer[strlen(buffer)-1] != '\n') {
        while (((ch = getchar()) != EOF) && (ch != '\n'))
            ;
        (void) fputs("?Line too long\n", stderr);
        return (-1);
    } else {
        buffer[strlen(buffer)-1] = '\0';
    }
    return (0);
}

static void
unknown_host(int error, char *hostname)
{
    if (error == TRY_AGAIN)
        (void) fprintf(stderr, "%s: Unknown host (try again later).\n",
            hostname);
    else
        (void) fprintf(stderr, "%s: Unknown host.\n", hostname);
}

static void
setpeer(int argc, char **argv)
{
    struct hostent *host;
    int error_num;
    struct in6_addr ipv6addr;
    struct in_addr ipv4addr;
    char *hostnameinput;

    if (argc < 2) {
        if (prompt_for_arg(line, sizeof (line), "to") == -1)
            return;
        makeargv(&argc, &argv);
    }
    if (argc > 3 || argc < 2) {
        (void) fprintf(stderr, "usage: %s host-name [port]\n",
            argv[0]);
        return;
    }
    hostnameinput = removebrackets(argv[1]);

    (void) memset(&sin6, 0, sizeof (sin6));
    sin6.sin6_family = AF_INET6;
    if (host = getipnodebyname(hostnameinput, AF_INET6,
        AI_ALL | AI_ADDRCONFIG | AI_V4MAPPED, &error_num)) {
        (void) memcpy(&sin6.sin6_addr, host->h_addr_list[0],
            host->h_length);
        /*
         * If host->h_name is a IPv4-mapped IPv6 literal, we'll convert
         * it to IPv4 literal address.
         */
        if ((inet_pton(AF_INET6, host->h_name, &ipv6addr) > 0) &&
            IN6_IS_ADDR_V4MAPPED(&ipv6addr)) {
            IN6_V4MAPPED_TO_INADDR(&ipv6addr, &ipv4addr);
            (void) inet_ntop(AF_INET, &ipv4addr, hostname,
                sizeof (hostname));
        } else {
            (void) strlcpy(hostname, host->h_name,
                sizeof (hostname));
        }
        freehostent(host);
    } else {
        /* Keeping with previous semantics */
        connected = 0;
        unknown_host(error_num, hostnameinput);
        return;
    }

    port = default_port;
    if (argc == 3) {
        port = atoi(argv[2]);
        if ((port < 1) || (port > 65535)) {
            (void) fprintf(stderr, "%s: bad port number\n",
                argv[2]);
            connected = 0;
            return;
        }
        port = htons(port);
    }
    connected = 1;
}

static struct modes {
    char *m_name;
    char *m_mode;
} modes[] = {
    { "ascii",  "netascii" },
    { "netascii",   "netascii" },
    { "binary",     "octet" },
    { "image",      "octet" },
    { "octet",     "octet" },
/*      { "mail",       "mail" },       */
    { 0,        0 }
};

static void
modecmd(int argc, char **argv)
{
    struct modes *p;

    if (argc < 2) {
        (void) fprintf(stderr, "Using %s mode to transfer files.\n",
            mode);
        return;
    }
    if (argc == 2) {
        for (p = modes; p->m_name != NULL; p++)
            if (strcmp(argv[1], p->m_name) == 0) {
                setmode(p->m_mode);
                return;
            }
        (void) fprintf(stderr, "%s: unknown mode\n", argv[1]);
        /* drop through and print usage message */
    }

    p = modes;
    (void) fprintf(stderr, "usage: %s [ %s", argv[0], p->m_name);
    for (p++; p->m_name != NULL; p++)
        (void) fprintf(stderr, " | %s", p->m_name);
    (void) puts(" ]");
}

/*ARGSUSED*/
static void
setbinary(int argc, char **argv)
{
    setmode("octet");
}

/*ARGSUSED*/
static void
setascii(int argc, char **argv)
{
    setmode("netascii");
}

static void
setmode(char *newmode)
{
    (void) strlcpy(mode, newmode, sizeof (mode));
    if (verbose)
        (void) printf("mode set to %s\n", mode);
}

/*
 * Send file(s).
 */
static void
put(int argc, char **argv)
{
    int fd;
    int n;
    char *cp, *targ;
    struct in6_addr ipv6addr;
    struct in_addr ipv4addr;
    char buf[PATH_MAX + 1], *argtail;

    if (argc < 2) {
        if (prompt_for_arg(line, sizeof (line), "file") == -1)
            return;
        makeargv(&argc, &argv);
    }
    if (argc < 2) {
        putusage(argv[0]);
        return;
    }
    targ = argv[argc - 1];
    if (finddelimiter(argv[argc - 1])) {
        char *cp;
        struct hostent *hp;
        int error_num;

        for (n = 1; n < argc - 1; n++)
            if (finddelimiter(argv[n])) {
                putusage(argv[0]);
                return;
            }
        cp = argv[argc - 1];
        targ = finddelimiter(cp);
        *targ++ = 0;
        cp = removebrackets(cp);

        if ((hp = getipnodebyname(cp,
            AF_INET6, AI_ALL | AI_ADDRCONFIG | AI_V4MAPPED,
            &error_num)) == NULL) {
            unknown_host(error_num, cp);
            return;
        }
        (void) memcpy(&sin6.sin6_addr, hp->h_addr_list[0],
            hp->h_length);

        sin6.sin6_family = AF_INET6;
        connected = 1;
        /*
         * If hp->h_name is a IPv4-mapped IPv6 literal, we'll convert
         * it to IPv4 literal address.
         */
        if ((inet_pton(AF_INET6, hp->h_name, &ipv6addr) > 0) &&
            IN6_IS_ADDR_V4MAPPED(&ipv6addr)) {
            IN6_V4MAPPED_TO_INADDR(&ipv6addr, &ipv4addr);
            (void) inet_ntop(AF_INET, &ipv4addr, hostname,
                sizeof (hostname));
        } else {
            (void) strlcpy(hostname, hp->h_name,
                sizeof (hostname));
        }
    }
    if (!connected) {
        (void) fputs("No target machine specified.\n", stderr);
        return;
    }
    if (argc < 4) {
        cp = argc == 2 ? tail(targ) : argv[1];
        fd = open(cp, O_RDONLY);
        if (fd < 0) {
            (void) fprintf(stderr, "tftp: %s: %s\n", cp,
                strerror(errno));
            return;
        }
        if (verbose)
            (void) printf("putting %s to %s:%s [%s]\n",
                cp, hostname, targ, mode);
        sin6.sin6_port = port;
        tftp_sendfile(fd, targ, mode);
        return;
    }
    /* this assumes the target is a directory */
    /* on a remote unix system.  hmmmm.  */
    if (strlen(targ) + 1 >= sizeof (buf)) {
        (void) fprintf(stderr, "tftp: filename too long: %s\n", targ);
        return;
    }
    for (n = 1; n < argc - 1; n++) {
        argtail = tail(argv[n]);
        if (snprintf(buf, sizeof (buf), "%s/%s", targ, argtail) >=
            sizeof (buf)) {
            (void) fprintf(stderr,
                "tftp: filename too long: %s/%s\n", targ, argtail);
            continue;
        }
        fd = open(argv[n], O_RDONLY);
        if (fd < 0) {
            (void) fprintf(stderr, "tftp: %s: %s\n", argv[n],
                strerror(errno));
            continue;
        }
        if (verbose)
            (void) printf("putting %s to %s:%s [%s]\n",
                argv[n], hostname, buf, mode);
        sin6.sin6_port = port;
        tftp_sendfile(fd, buf, mode);
    }
}

static void
putusage(char *s)
{
    (void) fprintf(stderr, "usage: %s file ... host:target, or\n"
        "       %s file ... target (when already connected)\n", s, s);
}

/*
 * Receive file(s).
 */
static void
get(int argc, char **argv)
{
    int fd;
    int n;
    char *cp;
    char *src;
    struct in6_addr ipv6addr;
    struct in_addr ipv4addr;
    int error_num;

    if (argc < 2) {
        if (prompt_for_arg(line, sizeof (line), "files") == -1)
            return;
        makeargv(&argc, &argv);
    }
    if (argc < 2) {
        getusage(argv[0]);
        return;
    }
    if (!connected) {
        for (n = 1; n < argc; n++)
            if (finddelimiter(argv[n]) == 0) {
                getusage(argv[0]);
                return;
            }
    }
    for (n = 1; n < argc; n++) {
        src = finddelimiter(argv[n]);
        if (src == NULL)
            src = argv[n];
        else {
            struct hostent *hp;
            char *hostnameinput;

            *src++ = 0;
            hostnameinput = removebrackets(argv[n]);

            if ((hp = getipnodebyname(hostnameinput, AF_INET6,
                AI_ALL | AI_ADDRCONFIG | AI_V4MAPPED,
                &error_num)) == NULL) {
                unknown_host(error_num, hostnameinput);
                continue;
            }
            (void) memcpy((caddr_t)&sin6.sin6_addr,
                hp->h_addr_list[0], hp->h_length);

            sin6.sin6_family = AF_INET6;
            connected = 1;
            /*
             * If hp->h_name is a IPv4-mapped IPv6 literal, we'll
             * convert it to IPv4 literal address.
             */
            if ((inet_pton(AF_INET6, hp->h_name, &ipv6addr) > 0) &&
                IN6_IS_ADDR_V4MAPPED(&ipv6addr)) {
                IN6_V4MAPPED_TO_INADDR(&ipv6addr, &ipv4addr);
                (void) inet_ntop(AF_INET, &ipv4addr, hostname,
                    sizeof (hostname));
            } else {
                (void) strlcpy(hostname, hp->h_name,
                    sizeof (hostname));
            }
        }
        if (argc < 4) {
            cp = argc == 3 ? argv[2] : tail(src);
            fd = creat(cp, 0644);
            if (fd < 0) {
                (void) fprintf(stderr, "tftp: %s: %s\n", cp,
                    strerror(errno));
                return;
            }
            if (verbose)
                (void) printf("getting from %s:%s to %s [%s]\n",
                    hostname, src, cp, mode);
            sin6.sin6_port = port;
            tftp_recvfile(fd, src, mode);
            break;
        }
        cp = tail(src); /* new .. jdg */
        fd = creat(cp, 0644);
        if (fd < 0) {
            (void) fprintf(stderr, "tftp: %s: %s\n", cp,
                strerror(errno));
            continue;
        }
        if (verbose)
            (void) printf("getting from %s:%s to %s [%s]\n",
                hostname, src, cp, mode);
        sin6.sin6_port = port;
        tftp_recvfile(fd, src, mode);
    }
}

static void
getusage(char *s)
{
    (void) fprintf(stderr, "usage: %s host:file host:file ... file, or\n"
        "       %s file file ... file if connected\n", s, s);
}

static void
setrexmt(int argc, char **argv)
{
    int t;

    if (argc < 2) {
        if (prompt_for_arg(line, sizeof (line), "value") == -1)
            return;
        makeargv(&argc, &argv);
    }
    if (argc != 2) {
        (void) fprintf(stderr, "usage: %s value\n", argv[0]);
        return;
    }
    t = atoi(argv[1]);
    if (t < 0)
        (void) fprintf(stderr, "%s: bad value\n", argv[1]);
    else
        rexmtval = t;
}

static void
settimeout(int argc, char **argv)
{
    int t;

    if (argc < 2) {
        if (prompt_for_arg(line, sizeof (line), "value") == -1)
            return;
        makeargv(&argc, &argv);
    }
    if (argc != 2) {
        (void) fprintf(stderr, "usage: %s value\n", argv[0]);
        return;
    }
    t = atoi(argv[1]);
    if (t < 0)
        (void) fprintf(stderr, "%s: bad value\n", argv[1]);
    else
        maxtimeout = t;
}

/*ARGSUSED*/
static void
status(int argc, char **argv)
{
    if (connected)
        (void) printf("Connected to %s.\n", hostname);
    else
        (void) puts("Not connected.");
    (void) printf("Mode: %s Verbose: %s Tracing: %s\n", mode,
        verbose ? "on" : "off", trace ? "on" : "off");
    (void) printf("Rexmt-interval: %d seconds, Max-timeout: %d seconds\n",
        rexmtval, maxtimeout);
    (void) printf("Transfer blocksize option: ");
    if (blksize == 0)
        (void) puts("off");
    else
        (void) printf("%d bytes\n", blksize);
    (void) printf("Server rexmt-interval option: ");
    if (srexmtval == 0)
        (void) puts("off");
    else
        (void) printf("%d seconds\n", srexmtval);
    (void) printf("Transfer size option: %s\n", tsize_opt ? "on" : "off");
}

/*ARGSUSED*/
static void
intr(int signum)
{
    (void) cancel_alarm();
    longjmp(toplevel, -1);
}

static char *
tail(char *filename)
{
    char *s;

    while (*filename != '\0') {
        s = strrchr(filename, '/');
        if (s == NULL)
            break;
        if (s[1] != '\0')
            return (&s[1]);
        *s = '\0';
    }
    return (filename);
}

/*
 * Command parser.
 */
static void
command(int top)
{
    struct cmd *c;
    int ch;

    if (!top)
        (void) putchar('\n');
    for (;;) {
        (void) printf("%s> ", prompt);
        if (fgets(line, sizeof (line), stdin) == NULL) {
            if (feof(stdin))
                quit(0, NULL);
            else
                continue;
        }

        /* Flush what didn't fit in the buffer */
        if (line[strlen(line)-1] != '\n') {
            while (((ch = getchar()) != EOF) && (ch != '\n'))
                ;
            (void) fputs("?Line too long\n", stderr);
        } else {
            line[strlen(line)-1] = '\0';
            if (line[0] != '\0') {
                int argc;
                char    **argv;

                makeargv(&argc, &argv);
                c = getcmd(argv[0]);
                if (c == AMBIGCMD)
                    (void) fputs("?Ambiguous command\n",
                        stderr);
                else if (c == NULL)
                    (void) fputs("?Invalid command\n",
                        stderr);
                else
                    (*c->handler)(argc, argv);
            }
        }
    }
}

static struct cmd *
getcmd(char *name)
{
    char *p, *q;
    struct cmd *c, *found;

    if (name == NULL)
        return (NULL);

    found = NULL;
    for (c = cmdtab; (p = c->name) != NULL; c++) {
        for (q = name; *q == *p++; q++)
            if (*q == '\0')     /* exact match? */
                return (c);
        if (*q == '\0')     /* the name was a prefix */
            found = (found == NULL) ? c : AMBIGCMD;
    }
    return (found);
}

/*
 * Given a string, this function returns the pointer to the delimiting ':'.
 * The string can contain an IPv6 literal address, which should be inside a
 * pair of brackets, e.g. [1::2]. Any colons inside a pair of brackets are not
 * accepted as delimiters. Returns NULL if delimiting ':' is not found.
 */
static char *
finddelimiter(char *str)
{
    boolean_t is_bracket_open = B_FALSE;
    char *cp;

    for (cp = str; *cp != '\0'; cp++) {
        if (*cp == '[')
            is_bracket_open = B_TRUE;
        else if (*cp == ']')
            is_bracket_open = B_FALSE;
        else if (*cp == ':' && !is_bracket_open)
            return (cp);
    }
    return (NULL);
}

/*
 * Given a string which is possibly surrounded by brackets, e.g. [1::2], this
 * function returns a string after removing those brackets. If the brackets
 * don't match, it does nothing.
 */
static char *
removebrackets(char *str)
{
    char *newstr = str;

    if ((str[0] == '[') && (str[strlen(str) - 1] == ']')) {
        newstr = str + 1;
        str[strlen(str) - 1] = '\0';
    }
    return (newstr);
}

#define MARGV_INC   20

/*
 * Slice a string up into argc/argv.
 */
static void
makeargv(int *argcp, char ***argvp)
{
    char *cp;
    char **argp;
    int argc;
    static char **argv;
    static int argv_size;

    if (argv == NULL) {
        argv_size = MARGV_INC;
        if ((argv = malloc(argv_size * sizeof (char *))) == NULL) {
            perror("tftp: malloc");
            exit(1);
        }
    }
    argc = 0;
    argp = argv;
    for (cp = line; *cp != '\0'; ) {
        while (isspace(*cp))
            cp++;
        if (*cp == '\0')
            break;
        *argp++ = cp;
        argc++;
        if (argc == argv_size) {
            argv_size += MARGV_INC;
            if ((argv = realloc(argv,
                argv_size * sizeof (char *))) == NULL) {
                perror("tftp: realloc");
                exit(1);
            }
            argp = argv + argc;
        }
        while (*cp != '\0' && !isspace(*cp))
            cp++;
        if (*cp == '\0')
            break;
        *cp++ = '\0';
    }
    *argp = NULL;

    *argcp = argc;
    *argvp = argv;
}

/*ARGSUSED*/
static void
quit(int argc, char **argv)
{
    exit(0);
}

/*
 * Help command.
 */
static void
help(int argc, char **argv)
{
    struct cmd *c;

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

/*ARGSUSED*/
static void
settrace(int argc, char **argv)
{
    trace = !trace;
    (void) printf("Packet tracing %s.\n", trace ? "on" : "off");
}

/*ARGSUSED*/
static void
setverbose(int argc, char **argv)
{
    verbose = !verbose;
    (void) printf("Verbose mode %s.\n", verbose ? "on" : "off");
}

static void
setblksize(int argc, char **argv)
{
    int b;

    if (argc < 2) {
        if (prompt_for_arg(line, sizeof (line), "value") == -1)
            return;
        makeargv(&argc, &argv);
    }
    if (argc != 2) {
        (void) fprintf(stderr, "usage: %s value\n", argv[0]);
        return;
    }
    b = atoi(argv[1]);

    /* RFC 2348 specifies valid blksize range, allow 0 to turn option off */
    if ((b < MIN_BLKSIZE || b > MAX_BLKSIZE) && b != 0)
        (void) fprintf(stderr, "%s: bad value\n", argv[1]);
    else
        blksize = b;
}

static void
setsrexmt(int argc, char **argv)
{
    int t;

    if (argc < 2) {
        if (prompt_for_arg(line, sizeof (line), "value") == -1)
            return;
        makeargv(&argc, &argv);
    }
    if (argc != 2) {
        (void) fprintf(stderr, "usage: %s value\n", argv[0]);
        return;
    }
    t = atoi(argv[1]);

    /* RFC 2349 specifies valid timeout range, allow 0 to turn option off */
    if ((t < MIN_TIMEOUT || t > MAX_TIMEOUT) && t != 0)
        (void) fprintf(stderr, "%s: bad value\n", argv[1]);
    else
        srexmtval = t;
}

static void
settsize(int argc, char **argv)
{
    if (argc != 1) {
        (void) fprintf(stderr, "usage: %s\n", argv[0]);
        return;
    }
    tsize_opt = !tsize_opt;
    (void) printf("Transfer size option %s.\n", tsize_opt ? "on" : "off");
}