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/*-

 * Copyright (c) 1985, 1988, 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. 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.

 * -

 * Portions Copyright (c) 1993 by Digital Equipment Corporation.

 *

 * Permission to use, copy, modify, and distribute this software for any

 * purpose with or without fee is hereby granted, provided that the above

 * copyright notice and this permission notice appear in all copies, and that

 * the name of Digital Equipment Corporation not be used in advertising or

 * publicity pertaining to distribution of the document or software without

 * specific, written prior permission.

 *

 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL

 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT

 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL

 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR

 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS

 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS

 * SOFTWARE.

 * -

 * --Copyright--

 */

/* Portions Copyright (c) 1993 Carlos Leandro and Rui Salgueiro

 *      Dep. Matematica Universidade de Coimbra, Portugal, Europe

 *

 * Permission to use, copy, modify, and distribute this software for any

 * purpose with or without fee is hereby granted, provided that the above

 * copyright notice and this permission notice appear in all copies.

 */

#if defined(LIBC_SCCS) && !defined(lint)

static char sccsid[] = "@(#)gethostnamadr.c     8.1 (Berkeley) 6/4/93";

static char rcsid[] = "$Id: getnetbydns.c,v 1.2 2001-09-27 12:01:53 chris Exp $";

#endif /* LIBC_SCCS and not lint */

#include <sys/param.h>

#include <sys/socket.h>

#include <netinet/in.h>

#include <arpa/inet.h>

#include <arpa/nameser.h>

#include <stdio.h>

#include <netdb.h>

#include <resolv.h>

#include <ctype.h>

#include <errno.h>

#include <string.h>

#include <unistd.h>

#include <syslog.h>

#include "res_config.h"

extern int h_errno;

#define BYADDR 0

#define BYNAME 1

#define MAXALIASES      35

#if PACKETSZ > 1024

#define MAXPACKET       PACKETSZ

#else

#define MAXPACKET       1024

#endif

typedef union {

        HEADER  hdr;

        u_char  buf[MAXPACKET];

} querybuf;

typedef union {

        long    al;

        char    ac;

} align;

static struct netent *

getnetanswer(answer, anslen, net_i)

        querybuf *answer;

        int anslen;

        int net_i;

{

        register HEADER *hp;

        register u_char *cp;

        register int n;

        u_char *eom;

        int type, class, buflen, ancount, qdcount, haveanswer, i, nchar;

        char aux1[MAXHOSTNAMELEN], aux2[MAXHOSTNAMELEN], ans[MAXHOSTNAMELEN];

        char *in, *st, *pauxt, *bp, **ap;

        char *paux1 = &aux1[0], *paux2 = &aux2[0], flag = 0;

static  struct netent net_entry;

static  char *net_aliases[MAXALIASES], netbuf[PACKETSZ];

        /*

         * find first satisfactory answer

         *

         *      answer --> +------------+  ( MESSAGE )

         *                 |   Header   |

         *                 +------------+

         *                 |  Question  | the question for the name server

         *                 +------------+

         *                 |   Answer   | RRs answering the question

         *                 +------------+

         *                 | Authority  | RRs pointing toward an authority

         *                 | Additional | RRs holding additional information

         *                 +------------+

         */

        eom = answer->buf + anslen;

        hp = &answer->hdr;

        ancount = ntohs(hp->ancount); /* #/records in the answer section */

        qdcount = ntohs(hp->qdcount); /* #/entries in the question section */

        bp = netbuf;

        buflen = sizeof(netbuf);

        cp = answer->buf + HFIXEDSZ;

        if (!qdcount) {

                if (hp->aa)

                        h_errno = HOST_NOT_FOUND;

                else

                        h_errno = TRY_AGAIN;

                return (NULL);

        }

        while (qdcount-- > 0)

                cp += __dn_skipname(cp, eom) + QFIXEDSZ;

        ap = net_aliases;

        *ap = NULL;

        net_entry.n_aliases = net_aliases;

        haveanswer = 0;

        while (--ancount >= 0 && cp < eom) {

                n = dn_expand(answer->buf, eom, cp, bp, buflen);

                if ((n < 0) || !res_dnok(bp))

                        break;

                cp += n;

                ans[0] = '\0';

                (void)strncpy(&ans[0], bp, sizeof(ans) - 1);

                ans[sizeof(ans) - 1] = '\0';

                GETSHORT(type, cp);

                GETSHORT(class, cp);

                cp += INT32SZ;          /* TTL */

                GETSHORT(n, cp);

                if (class == C_IN && type == T_PTR) {

                        n = dn_expand(answer->buf, eom, cp, bp, buflen);

                        if ((n < 0) || !res_hnok(bp)) {

                                cp += n;

                                return (NULL);

                        }

                        cp += n;

                        *ap++ = bp;

                        bp += strlen(bp) + 1;

                        net_entry.n_addrtype =

                                (class == C_IN) ? AF_INET : AF_UNSPEC;

                        haveanswer++;

                }

        }

        if (haveanswer) {

                *ap = NULL;

                switch (net_i) {

                case BYADDR:

                        net_entry.n_name = *net_entry.n_aliases;

                        net_entry.n_net = 0L;

                        break;

                case BYNAME:

                        in = *net_entry.n_aliases;

                        net_entry.n_name = &ans[0];

                        aux2[0] = '\0';

                        for (i = 0; i < 4; i++) {

                                for (st = in, nchar = 0;

                                     *st != '.';

                                     st++, nchar++)

                                        ;

                                if (nchar != 1 || *in != '0' || flag) {

                                        flag = 1;

                                        (void)strncpy(paux1,

                                                      (i==0) ? in : in-1,

                                                      (i==0) ?nchar : nchar+1);

                                        paux1[(i==0) ? nchar : nchar+1] = '\0';

                                        pauxt = paux2;

                                        paux2 = strcat(paux1, paux2);

                                        paux1 = pauxt;

                                }

                                in = ++st;

                        }

                        net_entry.n_net = inet_network(paux2);

                        break;

                }

                net_entry.n_aliases++;

                return (&net_entry);

        }

        h_errno = TRY_AGAIN;

        return (NULL);

}

struct netent *

_getnetbydnsaddr(net, net_type)

        register unsigned long net;

        register int net_type;

{

        unsigned int netbr[4];

        int nn, anslen;

        querybuf buf;

        char qbuf[MAXDNAME];

        unsigned long net2;

        struct netent *net_entry;

        if (net_type != AF_INET)

                return (NULL);

        for (nn = 4, net2 = net; net2; net2 >>= 8)

                netbr[--nn] = net2 & 0xff;

        switch (nn) {

        case 3:         /* Class A */

                sprintf(qbuf, "0.0.0.%u.in-addr.arpa", netbr[3]);

                break;

        case 2:         /* Class B */

                sprintf(qbuf, "0.0.%u.%u.in-addr.arpa", netbr[3], netbr[2]);

                break;

        case 1:         /* Class C */

                sprintf(qbuf, "0.%u.%u.%u.in-addr.arpa", netbr[3], netbr[2],

                    netbr[1]);

                break;

        case 0:  /* Class D - E */

                sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa", netbr[3], netbr[2],

                    netbr[1], netbr[0]);

                break;

        }

        anslen = res_query(qbuf, C_IN, T_PTR, (u_char *)&buf, sizeof(buf));

        if (anslen < 0) {

#ifdef DEBUG

                if (_res.options & RES_DEBUG)

                        printf("res_query failed\n");

#endif

                return (NULL);

        }

        net_entry = getnetanswer(&buf, anslen, BYADDR);

        if (net_entry) {

                unsigned u_net = net;   /* maybe net should be unsigned ? */

                /* Strip trailing zeros */

                while ((u_net & 0xff) == 0 && u_net != 0)

                        u_net >>= 8;

                net_entry->n_net = u_net;

                return (net_entry);

        }

        return (NULL);

}

struct netent *

_getnetbydnsname(net)

        register const char *net;

{

        int anslen;

        querybuf buf;

        char qbuf[MAXDNAME];

        if ((_res.options & RES_INIT) == 0 && res_init() == -1) {

                h_errno = NETDB_INTERNAL;

                return (NULL);

        }

        strncpy(qbuf, net, sizeof(qbuf) - 1);

        qbuf[sizeof(qbuf) - 1] = '\0';

        anslen = res_search(qbuf, C_IN, T_PTR, (u_char *)&buf, sizeof(buf));

        if (anslen < 0) {

#ifdef DEBUG

                if (_res.options & RES_DEBUG)

                        printf("res_query failed\n");

#endif

                return (NULL);

        }

        return getnetanswer(&buf, anslen, BYNAME);

}

void

_setnetdnsent(stayopen)

        int stayopen;

{

        if (stayopen)

                _res.options |= RES_STAYOPEN | RES_USEVC;

}

void

_endnetdnsent()

{

        _res.options &= ~(RES_STAYOPEN | RES_USEVC);

        res_close();

}