cmd-inet/usr.sbin/arp.c

	arp.c revision 69bb4bb45c98da60d21839c4dc3c01ea1be60585
/*
 * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */
/*
 * Copyright (c) 1984 Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Sun Microsystems, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */


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

/*
 * arp - display, set, and delete arp table entries
 */

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/ioctl.h>
#include <errno.h>
#include <netdb.h>
#include <net/if.h>
#include <net/if_arp.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <arpa/inet.h>
#include <net/if_types.h>
#include <net/if_dl.h>

static int file(char *);
static int set(int, char *[]);
static void get(char *);
static void delete(char *);
static void usage(void);

int
main(int argc, char *argv[])
{
    int c, nflags = 0, argsleft;
    int n_flag, a_flag, d_flag, f_flag, s_flag;

    n_flag = a_flag = d_flag = f_flag = s_flag = 0;

#define CASE(x, y)              \
        case x:             \
            if (nflags > 0) {   \
                usage();    \
                exit(1);    \
            } else          \
                y##_flag = 1;   \
                nflags++;   \
            break

    while ((c = getopt(argc, argv, "nadfs")) != EOF) {
        switch (c) {
        case '?':
            usage();
            exit(1);
            /* NOTREACHED */
            break;
        case 'n':
            n_flag = 1;
            break;
        CASE('a', a);
        CASE('d', d);
        CASE('f', f);
        CASE('s', s);
        }
    }

#undef CASE

    /*
     * -n only allowed with -a
     */
    if (n_flag && !a_flag) {
        usage();
        exit(1);
    }

    argsleft = argc - optind;

    if (a_flag && (argsleft == 0)) {
        /*
         * the easiest way to get the complete arp table
         * is to let netstat, which prints it as part of
         * the MIB statistics, do it.
         */
        (void) execl("/usr/bin/netstat", "netstat",
            (n_flag ? "-np" : "-p"),
            "-f", "inet", (char *)0);
        exit(1);

    } else if (s_flag && (argsleft >= 2)) {
        if (set(argsleft, &argv[optind]) != 0)
            exit(1);

    } else if (d_flag && (argsleft == 1)) {
        delete(argv[optind]);

    } else if (f_flag && (argsleft == 1)) {
        if (file(argv[optind]) != 0)
            exit(1);

    } else if ((nflags == 0) && (argsleft == 1)) {
        get(argv[optind]);

    } else {
        usage();
        exit(1);
    }
    return (0);
}

/*
 * Process a file to set standard arp entries
 */
static int
file(char *name)
{
    /*
     * A line of input can be:
     * <hostname> <macaddr> ["temp"] ["pub"] ["trail"] ["permanent"]
     */
#define MAX_LINE_LEN    (MAXHOSTNAMELEN + \
    sizeof (" xx:xx:xx:xx:xx:xx temp pub trail permanent\n"))
#define MIN_ARGS    2
#define MAX_ARGS    5

    FILE *fp;
    char line[MAX_LINE_LEN];
    int retval;

    if ((fp = fopen(name, "r")) == NULL) {
        (void) fprintf(stderr, "arp: cannot open %s\n", name);
        exit(1);
    }

    retval = 0;
    while (fgets(line, MAX_LINE_LEN, fp) != NULL) {
        char line_copy[MAX_LINE_LEN];
        char *args[MAX_ARGS];
        char *start;
        int i;

        /*
         * Keep a copy of the un-altered line for error
         * reporting.
         */
        (void) strlcpy(line_copy, line, MAX_LINE_LEN);

        start = line_copy;
        for (i = 0; i < MAX_ARGS; i++) {
            if ((args[i] = strtok(start, " \t\n")) == NULL)
                break;

            start = NULL;
        }

        if (i < MIN_ARGS) {
            (void) fprintf(stderr, "arp: bad line: %s\n",
                line);
            retval = 1;
            continue;
        }

        if (set(i, args) != 0)
            retval = 1;
    }

#undef  MAX_LINE_LEN
#undef  MIN_ARGS
#undef  MAX_ARGS

    (void) fclose(fp);
    return (retval);
}

/*
 * Set an individual arp entry
 */
static int
set(int argc, char *argv[])
{
    struct xarpreq ar;
    struct hostent *hp;
    struct sockaddr_in *sin;
    uchar_t *ea;
    int s;
    char *host = argv[0], *eaddr = argv[1];

    argc -= 2;
    argv += 2;
    (void) memset(&ar, 0, sizeof (ar));
    sin = (struct sockaddr_in *)&ar.xarp_pa;
    sin->sin_family = AF_INET;
    sin->sin_addr.s_addr = inet_addr(host);
    if (sin->sin_addr.s_addr == (in_addr_t)-1) {
        hp = gethostbyname(host);
        if (hp == NULL) {
            (void) fprintf(stderr, "arp: %s: unknown host\n",
                host);
            return (1);
        }
        (void) memcpy(&sin->sin_addr, hp->h_addr,
            sizeof (sin->sin_addr));
    }
    ea = _link_aton(eaddr, &s);
    if (ea == NULL) {
        if (s == -1) {
            (void) fprintf(stderr,
                "arp: invalid link layer address '%s'\n", eaddr);
            return (1);
        }
        perror("arp: nomem");
        exit(1);
    }
    ar.xarp_ha.sdl_alen = s;
    (void) memcpy(LLADDR(&ar.xarp_ha), ea, ar.xarp_ha.sdl_alen);
    free(ea);
    ar.xarp_ha.sdl_family = AF_LINK;
    ar.xarp_flags = ATF_PERM;
    while (argc-- > 0) {
        if (strncmp(argv[0], "temp", 4) == 0) {
            ar.xarp_flags &= ~ATF_PERM;
        } else if (strncmp(argv[0], "pub", 3) == 0) {
            ar.xarp_flags |= ATF_PUBL;
        } else if (strncmp(argv[0], "trail", 5) == 0) {
            ar.xarp_flags |= ATF_USETRAILERS;
        } else if (strcmp(argv[0], "permanent") == 0) {
            ar.xarp_flags |= ATF_AUTHORITY;
        } else {
            (void) fprintf(stderr,
                "arp: unknown keyword '%s'\n", argv[0]);
            return (1);
        }
        argv++;
    }

    if ((ar.xarp_flags & (ATF_PERM|ATF_AUTHORITY)) == ATF_AUTHORITY) {
        (void) fprintf(stderr, "arp: 'temp' and 'permanent' flags are "
            "not usable together.\n");
        return (1);
    }

    s = socket(AF_INET, SOCK_DGRAM, 0);
    if (s < 0) {
        perror("arp: socket");
        exit(1);
    }
    if (ioctl(s, SIOCSXARP, (caddr_t)&ar) < 0) {
        perror(host);
        exit(1);
    }
    (void) close(s);
    return (0);
}

/*
 * Display an individual arp entry
 */
static void
get(char *host)
{
    struct xarpreq ar;
    struct hostent *hp;
    struct sockaddr_in *sin;
    uchar_t *ea;
    int s;
    char *str = NULL;

    (void) memset(&ar, 0, sizeof (ar));
    sin = (struct sockaddr_in *)&ar.xarp_pa;
    sin->sin_family = AF_INET;
    sin->sin_addr.s_addr = inet_addr(host);
    if (sin->sin_addr.s_addr == (in_addr_t)-1) {
        hp = gethostbyname(host);
        if (hp == NULL) {
            (void) fprintf(stderr, "arp: %s: unknown host\n",
                host);
            exit(1);
        }
        (void) memcpy(&sin->sin_addr, hp->h_addr,
            sizeof (sin->sin_addr));
    }
    s = socket(AF_INET, SOCK_DGRAM, 0);
    if (s < 0) {
        perror("arp: socket");
        exit(1);
    }
    ar.xarp_ha.sdl_family = AF_LINK;
    if (ioctl(s, SIOCGXARP, (caddr_t)&ar) < 0) {
        if (errno == ENXIO)
            (void) printf("%s (%s) -- no entry\n",
                host, inet_ntoa(sin->sin_addr));
        else
            perror("SIOCGXARP");
        exit(1);
    }
    (void) close(s);
    ea = (uchar_t *)LLADDR(&ar.xarp_ha);
    if (ar.xarp_flags & ATF_COM) {
        str = _link_ntoa(ea, str, ar.xarp_ha.sdl_alen, IFT_OTHER);
        if (str != NULL) {
            (void) printf("%s (%s) at %s", host,
                inet_ntoa(sin->sin_addr), str);
            free(str);
        } else {
            perror("arp: nomem");
            exit(1);
        }
    } else {
        (void) printf("%s (%s) at (incomplete)", host,
            inet_ntoa(sin->sin_addr));
    }
    if (!(ar.xarp_flags & ATF_PERM))
        (void) printf(" temp");
    if (ar.xarp_flags & ATF_PUBL)
        (void) printf(" pub");
    if (ar.xarp_flags & ATF_USETRAILERS)
        (void) printf(" trail");
    if (ar.xarp_flags & ATF_AUTHORITY)
        (void) printf(" permanent");
    (void) printf("\n");
}

/*
 * Delete an arp entry
 */
static void
delete(char *host)
{
    struct xarpreq ar;
    struct hostent *hp;
    struct sockaddr_in *sin;
    int s;

    (void) memset(&ar, 0, sizeof (ar));
    sin = (struct sockaddr_in *)&ar.xarp_pa;
    sin->sin_family = AF_INET;
    sin->sin_addr.s_addr = inet_addr(host);
    if (sin->sin_addr.s_addr == (in_addr_t)-1) {
        hp = gethostbyname(host);
        if (hp == NULL) {
            (void) fprintf(stderr, "arp: %s: unknown host\n",
                host);
            exit(1);
        }
        (void) memcpy(&sin->sin_addr, hp->h_addr,
            sizeof (sin->sin_addr));
    }
    s = socket(AF_INET, SOCK_DGRAM, 0);
    if (s < 0) {
        perror("arp: socket");
        exit(1);
    }
    ar.xarp_ha.sdl_family = AF_LINK;
    if (ioctl(s, SIOCDXARP, (caddr_t)&ar) < 0) {
        if (errno == ENXIO)
            (void) printf("%s (%s) -- no entry\n",
                host, inet_ntoa(sin->sin_addr));
        else
            perror("SIOCDXARP");
        exit(1);
    }
    (void) close(s);
    (void) printf("%s (%s) deleted\n", host, inet_ntoa(sin->sin_addr));
}

static void
usage(void)
{
    (void) printf("Usage: arp hostname\n");
    (void) printf("       arp -a [-n]\n");
    (void) printf("       arp -d hostname\n");
    (void) printf("       arp -s hostname ether_addr "
        "[temp] [pub] [trail] [permanent]\n");
    (void) printf("       arp -f filename\n");
}