/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * ++Copyright++ 1985, 1988, 1993
 * -
 * 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. 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--
 */

#include <sys/param.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <netdb.h>
#include <resolv.h>
#include <ctype.h>
#include <errno.h>
#include <syslog.h>
#include <stdarg.h>
#include <nsswitch.h>

#include "netdb_private.h"
#include "res_config.h"

#define SPRINTF(x) ((size_t)sprintf x)

#ifdef DEBUG
static const char AskedForGot[] =
                "gethostby*.gethostanswer: asked for \"%s\", got \"%s\"";
#endif

#ifdef RESOLVSORT
static void addrsort(char **, int, res_state);
#endif

#ifdef DEBUG
static void dbg_printf(char *, int, res_state) __printflike(1, 0);
#endif

#define MAXPACKET       (64*1024)

typedef union {
    HEADER hdr;
    u_char buf[MAXPACKET];
} querybuf;

typedef union {
    int32_t al;
    char ac;
} align;

int _dns_ttl_;

#ifdef DEBUG
static void
dbg_printf(char *msg, int num, res_state res)
{
        if (res->options & RES_DEBUG) {
                int save = errno;

                printf(msg, num);
                errno = save;
        }
}
#else
# define dbg_printf(msg, num, res) /*nada*/
#endif

#define BOUNDED_INCR(x) \
        do { \
                cp += x; \
                if (cp > eom) { \
                        RES_SET_H_ERRNO(statp, NO_RECOVERY); \
                        return (-1); \
                } \
        } while (0)

#define BOUNDS_CHECK(ptr, count) \
        do { \
                if ((ptr) + (count) > eom) { \
                        RES_SET_H_ERRNO(statp, NO_RECOVERY); \
                        return (-1); \
                } \
        } while (0)

static int
gethostanswer(const querybuf *answer, int anslen, const char *qname, int qtype,
    struct hostent *he, struct hostent_data *hed, res_state statp)
{
        const HEADER *hp;
        const u_char *cp;
        int n;
        const u_char *eom, *erdata;
        char *bp, *ep, **ap, **hap;
        int type, class, ancount, qdcount;
        int haveanswer, had_error;
        int toobig = 0;
        char tbuf[MAXDNAME];
        const char *tname;
        int (*name_ok)(const char *);

        tname = qname;
        he->h_name = NULL;
        eom = answer->buf + anslen;
        switch (qtype) {
        case T_A:
        case T_AAAA:
                name_ok = res_hnok;
                break;
        case T_PTR:
                name_ok = res_dnok;
                break;
        default:
                RES_SET_H_ERRNO(statp, NO_RECOVERY);
                return (-1);    /* XXX should be abort(); */
        }
        /*
         * find first satisfactory answer
         */
        hp = &answer->hdr;
        ancount = ntohs(hp->ancount);
        qdcount = ntohs(hp->qdcount);
        bp = hed->hostbuf;
        ep = hed->hostbuf + sizeof hed->hostbuf;
        cp = answer->buf;
        BOUNDED_INCR(HFIXEDSZ);
        if (qdcount != 1) {
                RES_SET_H_ERRNO(statp, NO_RECOVERY);
                return (-1);
        }
        n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
        if ((n < 0) || !(*name_ok)(bp)) {
                RES_SET_H_ERRNO(statp, NO_RECOVERY);
                return (-1);
        }
        BOUNDED_INCR(n + QFIXEDSZ);
        if (qtype == T_A || qtype == T_AAAA) {
                /* res_send() has already verified that the query name is the
                 * same as the one we sent; this just gets the expanded name
                 * (i.e., with the succeeding search-domain tacked on).
                 */
                n = strlen(bp) + 1;             /* for the \0 */
                if (n >= MAXHOSTNAMELEN) {
                        RES_SET_H_ERRNO(statp, NO_RECOVERY);
                        return (-1);
                }
                he->h_name = bp;
                bp += n;
                /* The qname can be abbreviated, but h_name is now absolute. */
                qname = he->h_name;
        }
        ap = hed->host_aliases;
        *ap = NULL;
        he->h_aliases = hed->host_aliases;
        hap = hed->h_addr_ptrs;
        *hap = NULL;
        he->h_addr_list = hed->h_addr_ptrs;
        haveanswer = 0;
        had_error = 0;
        _dns_ttl_ = -1;
        while (ancount-- > 0 && cp < eom && !had_error) {
                n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
                if ((n < 0) || !(*name_ok)(bp)) {
                        had_error++;
                        continue;
                }
                cp += n;                        /* name */
                BOUNDS_CHECK(cp, 3 * INT16SZ + INT32SZ);
                type = _getshort(cp);
                cp += INT16SZ;                  /* type */
                class = _getshort(cp);
                cp += INT16SZ;                  /* class */
                if (qtype == T_A  && type == T_A)
                        _dns_ttl_ = _getlong(cp);
                cp += INT32SZ;                  /* TTL */
                n = _getshort(cp);
                cp += INT16SZ;                  /* len */
                BOUNDS_CHECK(cp, n);
                erdata = cp + n;
                if (class != C_IN) {
                        /* XXX - debug? syslog? */
                        cp += n;
                        continue;               /* XXX - had_error++ ? */
                }
                if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
                        if (ap >= &hed->host_aliases[_MAXALIASES-1])
                                continue;
                        n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
                        if ((n < 0) || !(*name_ok)(tbuf)) {
                                had_error++;
                                continue;
                        }
                        cp += n;
                        if (cp != erdata) {
                                RES_SET_H_ERRNO(statp, NO_RECOVERY);
                                return (-1);
                        }
                        /* Store alias. */
                        *ap++ = bp;
                        n = strlen(bp) + 1;     /* for the \0 */
                        if (n >= MAXHOSTNAMELEN) {
                                had_error++;
                                continue;
                        }
                        bp += n;
                        /* Get canonical name. */
                        n = strlen(tbuf) + 1;   /* for the \0 */
                        if (n > ep - bp || n >= MAXHOSTNAMELEN) {
                                had_error++;
                                continue;
                        }
                        strcpy(bp, tbuf);
                        he->h_name = bp;
                        bp += n;
                        continue;
                }
                if (qtype == T_PTR && type == T_CNAME) {
                        n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
                        if (n < 0 || !res_dnok(tbuf)) {
                                had_error++;
                                continue;
                        }
                        cp += n;
                        if (cp != erdata) {
                                RES_SET_H_ERRNO(statp, NO_RECOVERY);
                                return (-1);
                        }
                        /* Get canonical name. */
                        n = strlen(tbuf) + 1;   /* for the \0 */
                        if (n > ep - bp || n >= MAXHOSTNAMELEN) {
                                had_error++;
                                continue;
                        }
                        strcpy(bp, tbuf);
                        tname = bp;
                        bp += n;
                        continue;
                }
                if (type != qtype) {
#ifdef DEBUG
                        if (type != T_KEY && type != T_SIG &&
                            type != T_DNAME && type != T_RRSIG)
                                syslog(LOG_NOTICE|LOG_AUTH,
        "gethostby*.gethostanswer: asked for \"%s %s %s\", got type \"%s\"",
                                       qname, p_class(C_IN), p_type(qtype),
                                       p_type(type));
#endif
                        cp += n;
                        continue;               /* XXX - had_error++ ? */
                }
                switch (type) {
                case T_PTR:
                        if (strcasecmp(tname, bp) != 0) {
#ifdef DEBUG
                                syslog(LOG_NOTICE|LOG_AUTH,
                                       AskedForGot, qname, bp);
#endif
                                cp += n;
                                continue;       /* XXX - had_error++ ? */
                        }
                        n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
                        if ((n < 0) || !res_hnok(bp)) {
                                had_error++;
                                break;
                        }
#if MULTI_PTRS_ARE_ALIASES
                        cp += n;
                        if (cp != erdata) {
                                RES_SET_H_ERRNO(statp, NO_RECOVERY);
                                return (-1);
                        }
                        if (!haveanswer)
                                he->h_name = bp;
                        else if (ap < &hed->host_aliases[_MAXALIASES-1])
                                *ap++ = bp;
                        else
                                n = -1;
                        if (n != -1) {
                                n = strlen(bp) + 1;     /* for the \0 */
                                if (n >= MAXHOSTNAMELEN) {
                                        had_error++;
                                        break;
                                }
                                bp += n;
                        }
                        break;
#else
                        he->h_name = bp;
                        if (statp->options & RES_USE_INET6) {
                                n = strlen(bp) + 1;     /* for the \0 */
                                if (n >= MAXHOSTNAMELEN) {
                                        had_error++;
                                        break;
                                }
                                bp += n;
                                _map_v4v6_hostent(he, &bp, ep);
                        }
                        RES_SET_H_ERRNO(statp, NETDB_SUCCESS);
                        return (0);
#endif
                case T_A:
                case T_AAAA:
                        if (strcasecmp(he->h_name, bp) != 0) {
#ifdef DEBUG
                                syslog(LOG_NOTICE|LOG_AUTH,
                                       AskedForGot, he->h_name, bp);
#endif
                                cp += n;
                                continue;       /* XXX - had_error++ ? */
                        }
                        if (n != he->h_length) {
                                cp += n;
                                continue;
                        }
                        if (!haveanswer) {
                                int nn;

                                he->h_name = bp;
                                nn = strlen(bp) + 1;    /* for the \0 */
                                bp += nn;
                        }

                        bp += sizeof(align) - ((u_long)bp % sizeof(align));

                        if (bp + n >= ep) {
                                dbg_printf("size (%d) too big\n", n, statp);
                                had_error++;
                                continue;
                        }
                        if (hap >= &hed->h_addr_ptrs[_MAXADDRS-1]) {
                                if (!toobig++)
                                        dbg_printf("Too many addresses (%d)\n",
                                                _MAXADDRS, statp);
                                cp += n;
                                continue;
                        }
                        memcpy(*hap++ = bp, cp, n);
                        bp += n;
                        cp += n;
                        if (cp != erdata) {
                                RES_SET_H_ERRNO(statp, NO_RECOVERY);
                                return (-1);
                        }
                        break;
                default:
                        dbg_printf("Impossible condition (type=%d)\n", type,
                            statp);
                        RES_SET_H_ERRNO(statp, NO_RECOVERY);
                        return (-1);
                        /* BIND has abort() here, too risky on bad data */
                }
                if (!had_error)
                        haveanswer++;
        }
        if (haveanswer) {
                *ap = NULL;
                *hap = NULL;
# if defined(RESOLVSORT)
                /*
                 * Note: we sort even if host can take only one address
                 * in its return structures - should give it the "best"
                 * address in that case, not some random one
                 */
                if (statp->nsort && haveanswer > 1 && qtype == T_A)
                        addrsort(hed->h_addr_ptrs, haveanswer, statp);
# endif /*RESOLVSORT*/
                if (!he->h_name) {
                        n = strlen(qname) + 1;  /* for the \0 */
                        if (n > ep - bp || n >= MAXHOSTNAMELEN)
                                goto no_recovery;
                        strcpy(bp, qname);
                        he->h_name = bp;
                        bp += n;
                }
                if (statp->options & RES_USE_INET6)
                        _map_v4v6_hostent(he, &bp, ep);
                RES_SET_H_ERRNO(statp, NETDB_SUCCESS);
                return (0);
        }
 no_recovery:
        RES_SET_H_ERRNO(statp, NO_RECOVERY);
        return (-1);
}

/* XXX: for async DNS resolver in ypserv */
struct hostent *
__dns_getanswer(const char *answer, int anslen, const char *qname, int qtype)
{
        struct hostent *he;
        struct hostent_data *hed;
        int error;
        res_state statp;

        statp = __res_state();
        if ((he = __hostent_init()) == NULL ||
            (hed = __hostent_data_init()) == NULL) {
                RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
                return (NULL);
        }
        switch (qtype) {
        case T_AAAA:
                he->h_addrtype = AF_INET6;
                he->h_length = NS_IN6ADDRSZ;
                break;
        case T_A:
        default:
                he->h_addrtype = AF_INET;
                he->h_length = NS_INADDRSZ;
                break;
        }

        error = gethostanswer((const querybuf *)answer, anslen, qname, qtype,
            he, hed, statp);
        return (error == 0) ? he : NULL;
}

int
_dns_gethostbyname(void *rval, void *cb_data, va_list ap)
{
        const char *name;
        int af;
        char *buffer;
        size_t buflen;
        int *errnop, *h_errnop;
        struct hostent *hptr, he;
        struct hostent_data *hed;
        querybuf *buf;
        int n, type, error;
        res_state statp;

        name = va_arg(ap, const char *);
        af = va_arg(ap, int);
        hptr = va_arg(ap, struct hostent *);
        buffer = va_arg(ap, char *);
        buflen = va_arg(ap, size_t);
        errnop = va_arg(ap, int *);
        h_errnop = va_arg(ap, int *);

        *((struct hostent **)rval) = NULL;

        statp = __res_state();
        if ((hed = __hostent_data_init()) == NULL) {
                RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
                *h_errnop = statp->res_h_errno;
                return (NS_NOTFOUND);
        }

        he.h_addrtype = af;
        switch (af) {
        case AF_INET:
                he.h_length = NS_INADDRSZ;
                type = T_A;
                break;
        case AF_INET6:
                he.h_length = NS_IN6ADDRSZ;
                type = T_AAAA;
                break;
        default:
                RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
                *h_errnop = statp->res_h_errno;
                errno = EAFNOSUPPORT;
                return (NS_UNAVAIL);
        }

        if ((buf = malloc(sizeof(*buf))) == NULL) {
                RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
                *h_errnop = statp->res_h_errno;
                return (NS_NOTFOUND);
        }
        n = res_nsearch(statp, name, C_IN, type, buf->buf, sizeof(buf->buf));
        if (n < 0) {
                free(buf);
                dbg_printf("res_nsearch failed (%d)\n", n, statp);
                *h_errnop = statp->res_h_errno;
                return (NS_NOTFOUND);
        } else if (n > sizeof(buf->buf)) {
                free(buf);
                dbg_printf("static buffer is too small (%d)\n", n, statp);
                *h_errnop = statp->res_h_errno;
                return (NS_UNAVAIL);
        }
        error = gethostanswer(buf, n, name, type, &he, hed, statp);
        free(buf);
        if (error != 0) {
                *h_errnop = statp->res_h_errno;
                switch (statp->res_h_errno) {
                case HOST_NOT_FOUND:
                        return (NS_NOTFOUND);
                case TRY_AGAIN:
                        return (NS_TRYAGAIN);
                default:
                        return (NS_UNAVAIL);
                }
                /*NOTREACHED*/
        }
        if (__copy_hostent(&he, hptr, buffer, buflen) != 0) {
                *errnop = errno;
                RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
                *h_errnop = statp->res_h_errno;
                return (NS_RETURN);
        }
        RES_SET_H_ERRNO(statp, NETDB_SUCCESS);
        *((struct hostent **)rval) = hptr;
        return (NS_SUCCESS);
}

int
_dns_gethostbyaddr(void *rval, void *cb_data, va_list ap)
{
        const void *addr;
        socklen_t len;
        int af;
        char *buffer;
        size_t buflen;
        int *errnop, *h_errnop;
        const u_char *uaddr;
        struct hostent *hptr, he;
        struct hostent_data *hed;
        int n;
        querybuf *buf;
        char qbuf[MAXDNAME+1], *qp;
        res_state statp;
#ifdef SUNSECURITY
        struct hostdata rhd;
        struct hostent *rhe;
        char **haddr;
        u_long old_options;
        char hname2[MAXDNAME+1], numaddr[46];
        int ret_h_error;
#endif /*SUNSECURITY*/

        addr = va_arg(ap, const void *);
        len = va_arg(ap, socklen_t);
        af = va_arg(ap, int);
        hptr = va_arg(ap, struct hostent *);
        buffer = va_arg(ap, char *);
        buflen = va_arg(ap, size_t);
        errnop = va_arg(ap, int *);
        h_errnop = va_arg(ap, int *);
        uaddr = (const u_char *)addr;

        *((struct hostent **)rval) = NULL;

        statp = __res_state();
        if ((hed = __hostent_data_init()) == NULL) {
                RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
                *h_errnop = statp->res_h_errno;
                return (NS_NOTFOUND);
        }

        switch (af) {
        case AF_INET:
                (void) sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa",
                               (uaddr[3] & 0xff),
                               (uaddr[2] & 0xff),
                               (uaddr[1] & 0xff),
                               (uaddr[0] & 0xff));
                break;
        case AF_INET6:
                qp = qbuf;
                for (n = NS_IN6ADDRSZ - 1; n >= 0; n--) {
                        qp += SPRINTF((qp, "%x.%x.",
                                       uaddr[n] & 0xf,
                                       (uaddr[n] >> 4) & 0xf));
                }
                strlcat(qbuf, "ip6.arpa", sizeof(qbuf));
                break;
        default:
                abort();
        }
        if ((buf = malloc(sizeof(*buf))) == NULL) {
                RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
                *h_errnop = statp->res_h_errno;
                return NS_NOTFOUND;
        }
        n = res_nquery(statp, qbuf, C_IN, T_PTR, (u_char *)buf->buf,
            sizeof buf->buf);
        if (n < 0) {
                free(buf);
                dbg_printf("res_nquery failed (%d)\n", n, statp);
                *h_errnop = statp->res_h_errno;
                return (NS_UNAVAIL);
        }
        if (n > sizeof buf->buf) {
                free(buf);
                dbg_printf("static buffer is too small (%d)\n", n, statp);
                *h_errnop = statp->res_h_errno;
                return (NS_UNAVAIL);
        }
        if (gethostanswer(buf, n, qbuf, T_PTR, &he, hed, statp) != 0) {
                free(buf);
                *h_errnop = statp->res_h_errno;
                switch (statp->res_h_errno) {
                case HOST_NOT_FOUND:
                        return (NS_NOTFOUND);
                case TRY_AGAIN:
                        return (NS_TRYAGAIN);
                default:
                        return (NS_UNAVAIL);
                }
                /*NOTREACHED*/
        }
        free(buf);
#ifdef SUNSECURITY
        if (af == AF_INET) {
            /*
             * turn off search as the name should be absolute,
             * 'localhost' should be matched by defnames
             */
            strncpy(hname2, he.h_name, MAXDNAME);
            hname2[MAXDNAME] = '\0';
            old_options = statp->options;
            statp->options &= ~RES_DNSRCH;
            statp->options |= RES_DEFNAMES;
            memset(&rhd, 0, sizeof rhd);
            rhe = gethostbyname_r(hname2, &rhd.host, &rhd.data,
                sizeof(rhd.data), &ret_h_error);
            if (rhe == NULL) {
                if (inet_ntop(af, addr, numaddr, sizeof(numaddr)) == NULL)
                    strlcpy(numaddr, "UNKNOWN", sizeof(numaddr));
                syslog(LOG_NOTICE|LOG_AUTH,
                       "gethostbyaddr: No A record for %s (verifying [%s])",
                       hname2, numaddr);
                statp->options = old_options;
                RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
                *h_errnop = statp->res_h_errno;
                return (NS_NOTFOUND);
            }
            statp->options = old_options;
            for (haddr = rhe->h_addr_list; *haddr; haddr++)
                if (!memcmp(*haddr, addr, NS_INADDRSZ))
                        break;
            if (!*haddr) {
                if (inet_ntop(af, addr, numaddr, sizeof(numaddr)) == NULL)
                    strlcpy(numaddr, "UNKNOWN", sizeof(numaddr));
                syslog(LOG_NOTICE|LOG_AUTH,
                       "gethostbyaddr: A record of %s != PTR record [%s]",
                       hname2, numaddr);
                RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
                *h_errnop = statp->res_h_errno;
                return (NS_NOTFOUND);
            }
        }
#endif /*SUNSECURITY*/
        he.h_addrtype = af;
        he.h_length = len;
        memcpy(hed->host_addr, uaddr, len);
        hed->h_addr_ptrs[0] = (char *)hed->host_addr;
        hed->h_addr_ptrs[1] = NULL;
        if (af == AF_INET && (statp->options & RES_USE_INET6)) {
                _map_v4v6_address((char*)hed->host_addr, (char*)hed->host_addr);
                he.h_addrtype = AF_INET6;
                he.h_length = NS_IN6ADDRSZ;
        }
        if (__copy_hostent(&he, hptr, buffer, buflen) != 0) {
                *errnop = errno;
                RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
                *h_errnop = statp->res_h_errno;
                return (NS_RETURN);
        }
        RES_SET_H_ERRNO(statp, NETDB_SUCCESS);
        *((struct hostent **)rval) = hptr;
        return (NS_SUCCESS);
}

#ifdef RESOLVSORT
static void
addrsort(char **ap, int num, res_state res)
{
        int i, j;
        char **p;
        short aval[_MAXADDRS];
        int needsort = 0;

        p = ap;
        for (i = 0; i < num; i++, p++) {
            for (j = 0 ; (unsigned)j < res->nsort; j++)
                if (res->sort_list[j].addr.s_addr == 
                    (((struct in_addr *)(*p))->s_addr & res->sort_list[j].mask))
                        break;
            aval[i] = j;
            if (needsort == 0 && i > 0 && j < aval[i-1])
                needsort = i;
        }
        if (!needsort)
            return;

        while (needsort < num) {
            for (j = needsort - 1; j >= 0; j--) {
                if (aval[j] > aval[j+1]) {
                    char *hp;

                    i = aval[j];
                    aval[j] = aval[j+1];
                    aval[j+1] = i;

                    hp = ap[j];
                    ap[j] = ap[j+1];
                    ap[j+1] = hp;

                } else
                    break;
            }
            needsort++;
        }
}
#endif

void
_sethostdnsent(int stayopen)
{
        res_state statp;

        statp = __res_state();
        if ((statp->options & RES_INIT) == 0 && res_ninit(statp) == -1)
                return;
        if (stayopen)
                statp->options |= RES_STAYOPEN | RES_USEVC;
}

void
_endhostdnsent(void)
{
        res_state statp;

        statp = __res_state();
        statp->options &= ~(RES_STAYOPEN | RES_USEVC);
        res_nclose(statp);
}