kadmin/kdcmgr/klookup.c

	klookup.c revision 1fceb383a3f0b59711832b9dc4e8329d7f216604
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (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 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

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

#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <resolv.h>
#include <netdb.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <ctype.h>

int
/* ARGSUSED */
main(int argc, char **argv)
{
    unsigned char answer[NS_MAXMSG], *ansp = NULL, *end;
    int len = 0, anslen, hostlen, nq, na, type, class;
    char hostname[MAXHOSTNAMELEN], *cp;
    struct __res_state stat;
    int found = 0;
    HEADER *h;

    if (argc != 1)
        exit(1);

    if (gethostname(hostname, MAXHOSTNAMELEN) != 0)
        exit(1);

    (void) memset(&stat, 0, sizeof (stat));

    if (res_ninit(&stat) == -1)
        exit(1);

    anslen = sizeof (answer);
    len = res_nsearch(&stat, hostname, C_IN, T_A, answer, anslen);

    if (len < sizeof (HEADER))
        exit(1);

    ansp = answer;
    end = ansp + anslen;

    /* LINTED */
    h = (HEADER *)answer;
    nq = ntohs(h->qdcount);
    na = ntohs(h->ancount);
    ansp += HFIXEDSZ;

    if (nq != 1 || na < 1)
        exit(1);

    hostlen = sizeof (hostname);
    len = dn_expand(answer, end, ansp, hostname, hostlen);
    if (len < 0)
        exit(1);

    ansp += len + QFIXEDSZ;

    if (ansp > end)
        exit(1);

    while (na-- > 0 && ansp < end) {
        len = dn_expand(answer, end, ansp, hostname, hostlen);

        if (len < 0)
            continue;
        ansp += len;            /* hostname */
        type = ns_get16(ansp);
        ansp += INT16SZ;        /* type */
        class = ns_get16(ansp);
        ansp += INT16SZ;        /* class */
        ansp += INT32SZ;        /* ttl */
        len = ns_get16(ansp);
        ansp += INT16SZ;        /* size */
        ansp += len;
        if (type == T_A && class == C_IN) {
            found = 1;
            break;
        }
    }

    if (found != 1)
        exit(1);

    for (cp = hostname; *cp; cp++) {
        *cp = tolower(*cp);
    }

    (void) printf("%s\n", hostname);

    return (0);
}