/*
 * 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 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */
/*
 * Copyright 2014 Nexenta Systems, Inc.  All rights reserved.
 */

#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>

/*
 * Private resolver of target and type with arguments:
 * klooukp [ target [ RR_type ] ]
 *
 * Utitilizes DNS lookups to discover domain and realm information.  This CLI
 * is used primarily by kdcmgr(8) and kclient(8).
 */

int
/* ARGSUSED */
main(int argc, char **argv)
{
        unsigned char answer[NS_MAXMSG], *ansp = NULL, *end, a, b, c, d;
        int len = 0, anslen, hostlen, nq, na, type, class;
        int ttl __unused, priority __unused, weight __unused, port, size;
        char name[NS_MAXDNAME], *cp, *typestr = NULL;
        char nbuf[INET6_ADDRSTRLEN];
        struct __res_state stat;
        int found = 0;
        int rr_type = T_A;
        HEADER *h;

        type = T_A;

        if (argc > 3)
                exit(1);

        if (argc == 1) {
                if (gethostname(name, MAXHOSTNAMELEN) != 0)
                        exit(1);
        } else {
                (void) strncpy(name, (char *)argv[1], NS_MAXDNAME);
                if (argc == 3) {
                        typestr = argv[2];

                        switch (*typestr) {
                        case 'A':
                                rr_type = T_A;
                                break;
                        case 'C':
                                rr_type = T_CNAME;
                                break;
                        case 'I':
                                rr_type = T_A;
                                break;
                        case 'P':
                                rr_type = T_PTR;
                                (void) sscanf(name, "%hhd.%hhd.%hhd.%hhd",
                                    &a, &b, &c, &d);
                                (void) sprintf(name, "%d.%d.%d.%d.in-addr.arpa",
                                    d, c, b, a);
                                break;
                        case 'S':
                                rr_type = T_SRV;
                                break;
                        default:
                                exit(1);
                        }
                }
        }

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

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

        anslen = sizeof (answer);
        len = res_nsearch(&stat, name, C_IN, rr_type, answer, anslen);

        if (len < sizeof (HEADER)) {
                res_ndestroy(&stat);
                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) {
                res_ndestroy(&stat);
                exit(1);
        }

        hostlen = sizeof (name);
        len = dn_expand(answer, end, ansp, name, hostlen);
        if (len < 0) {
                res_ndestroy(&stat);
                exit(1);
        }

        ansp += len + QFIXEDSZ;

        if (ansp > end) {
                res_ndestroy(&stat);
                exit(1);
        }

        while (na-- > 0 && ansp < end) {

                len = dn_expand(answer, end, ansp, name, hostlen);

                if (len < 0)
                        continue;
                ansp += len;                    /* name */
                NS_GET16(type, ansp);           /* type */
                NS_GET16(class, ansp);          /* class */
                NS_GET32(ttl, ansp);            /* ttl */
                NS_GET16(size, ansp);           /* size */

                if ((ansp + size) > end) {
                        res_ndestroy(&stat);
                        exit(1);
                }
                if (type == T_SRV) {
                        NS_GET16(priority, ansp);
                        NS_GET16(weight, ansp);
                        NS_GET16(port, ansp);
                        len = dn_expand(answer, end, ansp, name, hostlen);
                        if (len < 0) {
                                res_ndestroy(&stat);
                                exit(1);
                        }
                        for (cp = name; *cp; cp++) {
                                *cp = tolower(*cp);
                        }
                        (void) printf("%s %d\n", name, port);
                } else if (typestr && *typestr == 'I') {
                        (void) inet_ntop(AF_INET, (void *)ansp, nbuf,
                            INET6_ADDRSTRLEN);
                        len = size;
                        (void) printf("%s\n", nbuf);
                } else if (type == T_PTR) {
                        len = dn_expand(answer, end, ansp, name, hostlen);
                        if (len < 0) {
                                res_ndestroy(&stat);
                                exit(1);
                        }
                }
                ansp += len;
                if (type == rr_type && class == C_IN) {
                        found = 1;
                        if (type != T_SRV && !(typestr && *typestr == 'I'))
                                break;
                }
        }

        if (found != 1) {
                res_ndestroy(&stat);
                exit(1);
        }

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

        if (type != T_SRV && !(typestr && *typestr == 'I'))
                (void) printf("%s\n", name);

        res_ndestroy(&stat);

        return (0);
}