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res_send.c

/*
 * ++Copyright++ 1985, 1989, 1993
 * -
 * Copyright (c) 1985, 1989, 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--
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)res_send.c    8.1 (Berkeley) 6/4/93";
static char rcsid[] = "$Id: res_send.c,v 1.1.1.1 1998/02/10 21:01:47 mea Exp $";
#endif /* LIBC_SCCS and not lint */

      /* change this to "0"
       * if you talk to a lot
       * of multi-homed SunOS
       * ("broken") name servers.
       */
#define     CHECK_SRVR_ADDR   1     /* XXX - should be in options.h */

/*
 * Send query to name server and wait for reply.
 */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/time.h>
#include <sys/socket.h>
#if defined(_AIX) /* AIX 3.2.5e5 requires this */
#include <sys/select.h>
#endif
#include <sys/uio.h>
#include <netinet/in.h>
#include "arpa/nameser.h"
#include "arpa/inet.h"

#include <stdio.h>
#include "netdb.h"
#include <errno.h>
#include "resolv.h"
#if defined(BSD) && (BSD >= 199306)
# include <stdlib.h>
# include <string.h>
# include <unistd.h>
#else
# include "portability.h"
#endif

#if defined(USE_OPTIONS_H)
# include "options.h"
#endif

void _res_close __P((void));

static int s = -1;      /* socket used for communications */
static int connected = 0;     /* is the socket connected */
static int vc = 0;      /* is the socket a virtual ciruit? */

#ifndef FD_SET
/* XXX - should be in portability.h */
#define     NFDBITS           32
#define     FD_SETSIZE  32
#define     FD_SET(n, p)      ((p)->fds_bits[(n)/NFDBITS] |= (1 << ((n) % NFDBITS)))
#define     FD_CLR(n, p)      ((p)->fds_bits[(n)/NFDBITS] &= ~(1 << ((n) % NFDBITS)))
#define     FD_ISSET(n, p)    ((p)->fds_bits[(n)/NFDBITS] & (1 << ((n) % NFDBITS)))
#define FD_ZERO(p)      memset((char *)(p), 0, sizeof(*(p)))
#endif

/* XXX - this should be done in portability.h */
#if (defined(BSD) && (BSD >= 199103)) || defined(linux)
# define CAN_RECONNECT 1
#else
# define CAN_RECONNECT 0
#endif

#ifndef DEBUG
#   define Dprint(cond, args) /*empty*/
#   define DprintQ(cond, args, query, size) /*empty*/
#   define Aerror(file, string, error, address) /*empty*/
#   define Perror(file, string, error) /*empty*/
#else
#   define Dprint(cond, args) if (cond) {fprintf args;} else {}
#   define DprintQ(cond, args, query, size) if (cond) {\
                  fprintf args;\
                  __fp_nquery(query, size, stdout);\
            } else {}
    static void
    Aerror(file, string, error, address)
      FILE *file;
      char *string;
      int error;
      struct sockaddr_in address;
    {
      int save = errno;

      if (_res.options & RES_DEBUG) {
            fprintf(file, "res_send: %s ([%s].%u): %s\n",
                  string,
                  inet_ntoa(address.sin_addr),
                  ntohs(address.sin_port),
                  strerror(error));
      }
      errno = save;
    }
    static void
    Perror(file, string, error)
      FILE *file;
      char *string;
      int error;
    {
      int save = errno;

      if (_res.options & RES_DEBUG) {
            fprintf(file, "res_send: %s: %s\n",
                  string, strerror(error));
      }
      errno = save;
    }
#endif

static res_send_qhook Qhook = NULL;
static res_send_rhook Rhook = NULL;

void
res_send_setqhook(hook)
      res_send_qhook hook;
{

      Qhook = hook;
}

void
res_send_setrhook(hook)
      res_send_rhook hook;
{

      Rhook = hook;
}

/* int
 * res_isourserver(ina)
 *    looks up "ina" in _res.ns_addr_list[]
 * returns:
 *    0  : not found
 *    >0 : found
 * author:
 *    paul vixie, 29may94
 */
int
res_isourserver(inp)
      const struct sockaddr_in *inp;
{
      struct sockaddr_in ina;
      register int ns, ret;

      ina = *inp;
      ret = 0;
      for (ns = 0;  ns < _res.nscount;  ns++) {
            register const struct sockaddr_in *srv = &_res.nsaddr_list[ns];

            if (srv->sin_family == ina.sin_family &&
                srv->sin_port == ina.sin_port &&
                (srv->sin_addr.s_addr == INADDR_ANY ||
                 srv->sin_addr.s_addr == ina.sin_addr.s_addr)) {
                  ret++;
                  break;
            }
      }
      return (ret);
}

/* int
 * res_nameinquery(name, type, class, buf, eom)
 *    look for (name,type,class) in the query section of packet (buf,eom)
 * returns:
 *    -1 : format error
 *    0  : not found
 *    >0 : found
 * author:
 *    paul vixie, 29may94
 */
int
res_nameinquery(name, type, class, buf, eom)
      const char *name;
      register int type, class;
      const u_char *buf, *eom;
{
      register const u_char *cp = buf + HFIXEDSZ;
      int qdcount = ntohs(((HEADER*)buf)->qdcount);

      while (qdcount-- > 0) {
            char tname[MAXDNAME+1];
            register int n, ttype, tclass;

            n = dn_expand(buf, eom, cp, tname, sizeof tname);
            if (n < 0)
                  return (-1);
            cp += n;
            ttype = _getshort(cp); cp += INT16SZ;
            tclass = _getshort(cp); cp += INT16SZ;
            if (ttype == type &&
                tclass == class &&
                strcasecmp(tname, name) == 0)
                  return (1);
      }
      return (0);
}

/* int
 * res_queriesmatch(buf1, eom1, buf2, eom2)
 *    is there a 1:1 mapping of (name,type,class)
 *    in (buf1,eom1) and (buf2,eom2)?
 * returns:
 *    -1 : format error
 *    0  : not a 1:1 mapping
 *    >0 : is a 1:1 mapping
 * author:
 *    paul vixie, 29may94
 */
int
res_queriesmatch(buf1, eom1, buf2, eom2)
      const u_char *buf1, *eom1;
      const u_char *buf2, *eom2;
{
      register const u_char *cp = buf1 + HFIXEDSZ;
      int qdcount = ntohs(((HEADER*)buf1)->qdcount);

      if (qdcount != ntohs(((HEADER*)buf2)->qdcount))
            return (0);
      while (qdcount-- > 0) {
            char tname[MAXDNAME+1];
            register int n, ttype, tclass;

            n = dn_expand(buf1, eom1, cp, tname, sizeof tname);
            if (n < 0)
                  return (-1);
            cp += n;
            ttype = _getshort(cp);  cp += INT16SZ;
            tclass = _getshort(cp); cp += INT16SZ;
            if (!res_nameinquery(tname, ttype, tclass, buf2, eom2))
                  return (0);
      }
      return (1);
}

int
res_send(buf, buflen, ans, anssiz)
      const u_char *buf;
      int buflen;
      u_char *ans;
      int anssiz;
{
      HEADER *hp = (HEADER *) buf;
      HEADER *anhp = (HEADER *) ans;
      int gotsomewhere, connreset, terrno, try, v_circuit, resplen, ns;
      register int n;
      u_int badns;      /* XXX NSMAX can't exceed #/bits in this var */

      if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
            /* errno should have been set by res_init() in this case. */
            return (-1);
      }
      DprintQ((_res.options & RES_DEBUG) || (_res.pfcode & RES_PRF_QUERY),
            (stdout, ";; res_send()\n"), buf, buflen);
      v_circuit = (_res.options & RES_USEVC) || buflen > PACKETSZ;
      gotsomewhere = 0;
      connreset = 0;
      terrno = ETIMEDOUT;
      badns = 0;

      /*
       * Send request, RETRY times, or until successful
       */
      for (try = 0; try < _res.retry; try++) {
          for (ns = 0; ns < _res.nscount; ns++) {
            struct sockaddr_in *nsap = &_res.nsaddr_list[ns];
    same_ns:
            if (badns & (1 << ns)) {
                  _res_close();
                  goto next_ns;
            }

            if (Qhook) {
                  int done = 0, loops = 0;

                  do {
                        res_sendhookact act;

                        act = (*Qhook)(&nsap, &buf, &buflen,
                                     ans, anssiz, &resplen);
                        switch (act) {
                        case res_goahead:
                              done = 1;
                              break;
                        case res_nextns:
                              _res_close();
                              goto next_ns;
                        case res_done:
                              return (resplen);
                        case res_modified:
                              /* give the hook another try */
                              if (++loops < 42) /*doug adams*/
                                    break;
                              /*FALLTHROUGH*/
                        case res_error:
                              /*FALLTHROUGH*/
                        default:
                              return (-1);
                        }
                  } while (!done);
            }

            Dprint(_res.options & RES_DEBUG,
                   (stdout, ";; Querying server (# %d) address = %s\n",
                  ns + 1, inet_ntoa(nsap->sin_addr)));

            if (v_circuit) {
                  int truncated;
                  struct iovec iov[2];
                  u_short len;
                  u_char *cp;

                  /*
                   * Use virtual circuit;
                   * at most one attempt per server.
                   */
                  try = _res.retry;
                  truncated = 0;
                  if ((s < 0) || (!vc)) {
                        if (s >= 0)
                              _res_close();

                        s = socket(PF_INET, SOCK_STREAM, 0);
                        if (s < 0) {
                              terrno = errno;
                              Perror(stderr, "socket(vc)", errno);
                              return (-1);
                        }
                        errno = 0;
                        if (connect(s, (struct sockaddr *)nsap,
                                  sizeof(struct sockaddr)) < 0) {
                              terrno = errno;
                              Aerror(stderr, "connect/vc",
                                     errno, *nsap);
                              badns |= (1 << ns);
                              _res_close();
                              goto next_ns;
                        }
                        vc = 1;
                  }
                  /*
                   * Send length & message
                   */
                  putshort((u_short)buflen, (u_char*)&len);
                  iov[0].iov_base = (caddr_t)&len;
                  iov[0].iov_len = INT16SZ;
                  iov[1].iov_base = (caddr_t)buf;
                  iov[1].iov_len = buflen;
                  if (writev(s, iov, 2) != (INT16SZ + buflen)) {
                        terrno = errno;
                        Perror(stderr, "write failed", errno);
                        badns |= (1 << ns);
                        _res_close();
                        goto next_ns;
                  }
                  /*
                   * Receive length & response
                   */
read_len:
                  cp = ans;
                  len = INT16SZ;
                  while ((n = read(s, (char *)cp, (int)len)) > 0) {
                        cp += n;
                        if ((len -= n) <= 0)
                              break;
                  }
                  if (n <= 0) {
                        terrno = errno;
                        Perror(stderr, "read failed", errno);
                        _res_close();
                        /*
                         * A long running process might get its TCP
                         * connection reset if the remote server was
                         * restarted.  Requery the server instead of
                         * trying a new one.  When there is only one
                         * server, this means that a query might work
                         * instead of failing.  We only allow one reset
                         * per query to prevent looping.
                         */
                        if (terrno == ECONNRESET && !connreset) {
                              connreset = 1;
                              _res_close();
                              goto same_ns;
                        }
                        _res_close();
                        goto next_ns;
                  }
                  resplen = _getshort(ans);
                  if (resplen > anssiz) {
                        Dprint(_res.options & RES_DEBUG,
                               (stdout, ";; response truncated\n")
                               );
                        truncated = 1;
                        len = anssiz;
                  } else
                        len = resplen;
                  cp = ans;
                  while (len != 0 &&
                         (n = read(s, (char *)cp, (int)len)) > 0) {
                        cp += n;
                        len -= n;
                  }
                  if (n <= 0) {
                        terrno = errno;
                        Perror(stderr, "read(vc)", errno);
                        _res_close();
                        goto next_ns;
                  }
                  if (truncated) {
                        /*
                         * Flush rest of answer
                         * so connection stays in synch.
                         */
                        anhp->tc = 1;
                        len = resplen - anssiz;
                        while (len != 0) {
                              char junk[PACKETSZ];

                              n = (len > sizeof(junk)
                                   ? sizeof(junk)
                                   : len);
                              if ((n = read(s, junk, n)) > 0)
                                    len -= n;
                              else
                                    break;
                        }
                  }
                  /*
                   * The calling applicating has bailed out of
                   * a previous call and failed to arrange to have
                   * the circuit closed or the server has got
                   * itself confused. Anyway drop the packet and
                   * wait for the correct one.
                   */
                  if (hp->id != anhp->id) {
                        DprintQ((_res.options & RES_DEBUG) ||
                              (_res.pfcode & RES_PRF_REPLY),
                              (stdout, ";; old answer (unexpected):\n"),
                              ans, (resplen>anssiz)?anssiz:resplen);
                        goto read_len;
                  }
            } else {
                  /*
                   * Use datagrams.
                   */
                  struct timeval timeout;
                  fd_set dsmask;
                  struct sockaddr_in from;
                  int fromlen;

                  if ((s < 0) || vc) {
                        if (vc)
                              _res_close();
                        s = socket(PF_INET, SOCK_DGRAM, 0);
                        if (s < 0) {
#if !CAN_RECONNECT
 bad_dg_sock:
#endif
                              terrno = errno;
                              Perror(stderr, "socket(dg)", errno);
                              return (-1);
                        }
                        connected = 0;
                  }
                  /*
                   * On a 4.3BSD+ machine (client and server,
                   * actually), sending to a nameserver datagram
                   * port with no nameserver will cause an
                   * ICMP port unreachable message to be returned.
                   * If our datagram socket is "connected" to the
                   * server, we get an ECONNREFUSED error on the next
                   * socket operation, and select returns if the
                   * error message is received.  We can thus detect
                   * the absence of a nameserver without timing out.
                   * If we have sent queries to at least two servers,
                   * however, we don't want to remain connected,
                   * as we wish to receive answers from the first
                   * server to respond.
                   */
                  if (_res.nscount == 1 || (try == 0 && ns == 0)) {
                        /*
                         * Connect only if we are sure we won't
                         * receive a response from another server.
                         */
                        if (!connected) {
                              if (connect(s, (struct sockaddr *)nsap,
                                        sizeof(struct sockaddr)
                                        ) < 0) {
                                    Aerror(stderr,
                                           "connect(dg)",
                                           errno, *nsap);
                                    badns |= (1 << ns);
                                    _res_close();
                                    goto next_ns;
                              }
                              connected = 1;
                        }
                        if (send(s, (char*)buf, buflen, 0) != buflen) {
                              Perror(stderr, "send", errno);
                              badns |= (1 << ns);
                              _res_close();
                              goto next_ns;
                        }
                  } else {
                        /*
                         * Disconnect if we want to listen
                         * for responses from more than one server.
                         */
                        if (connected) {
#if CAN_RECONNECT
                              struct sockaddr_in no_addr;

                              no_addr.sin_family = AF_INET;
                              no_addr.sin_addr.s_addr = INADDR_ANY;
                              no_addr.sin_port = 0;
                              (void) connect(s,
                                           (struct sockaddr *)
                                            &no_addr,
                                           sizeof(no_addr));
#else
                              int s1 = socket(PF_INET, SOCK_DGRAM,0);
                              if (s1 < 0)
                                    goto bad_dg_sock;
                              (void) dup2(s1, s);
                              (void) close(s1);
                              Dprint(_res.options & RES_DEBUG,
                                     (stdout, ";; new DG socket\n"))
#endif
                              connected = 0;
                              errno = 0;
                        }
                        if (sendto(s, (char*)buf, buflen, 0,
                                 (struct sockaddr *)nsap,
                                 sizeof(struct sockaddr))
                            != buflen) {
                              Aerror(stderr, "sendto", errno, *nsap);
                              badns |= (1 << ns);
                              _res_close();
                              goto next_ns;
                        }
                  }

                  /*
                   * Wait for reply
                   */
                  timeout.tv_sec = (_res.retrans << try);
                  if (try > 0)
                        timeout.tv_sec /= _res.nscount;
                  if ((long) timeout.tv_sec <= 0)
                        timeout.tv_sec = 1;
                  timeout.tv_usec = 0;
    wait:
                  FD_ZERO(&dsmask);
                  FD_SET(s, &dsmask);
                  n = select(s+1, &dsmask, (fd_set *)NULL,
                           (fd_set *)NULL, &timeout);
                  if (n < 0) {
                        if (errno == EINTR)
                              goto wait;
                        Perror(stderr, "select", errno);
                        _res_close();
                        goto next_ns;
                  }
                  if (n == 0) {
                        /*
                         * timeout
                         */
                        Dprint(_res.options & RES_DEBUG,
                               (stdout, ";; timeout\n"));
                        gotsomewhere = 1;
                        _res_close();
                        goto next_ns;
                  }
                  errno = 0;
                  fromlen = sizeof(struct sockaddr_in);
                  resplen = recvfrom(s, (char*)ans, anssiz, 0,
                                 (struct sockaddr *)&from, &fromlen);
                  if (resplen <= 0) {
                        Perror(stderr, "recvfrom", errno);
                        _res_close();
                        goto next_ns;
                  }
                  gotsomewhere = 1;
                  if (hp->id != anhp->id) {
                        /*
                         * response from old query, ignore it.
                         * XXX - potential security hazard could
                         *     be detected here.
                         */
                        DprintQ((_res.options & RES_DEBUG) ||
                              (_res.pfcode & RES_PRF_REPLY),
                              (stdout, ";; old answer:\n"),
                              ans, (resplen>anssiz)?anssiz:resplen);
                        goto wait;
                  }
#if CHECK_SRVR_ADDR
                  if (!(_res.options & RES_INSECURE1) &&
                      !res_isourserver(&from)) {
                        /*
                         * response from wrong server? ignore it.
                         * XXX - potential security hazard could
                         *     be detected here.
                         */
                        DprintQ((_res.options & RES_DEBUG) ||
                              (_res.pfcode & RES_PRF_REPLY),
                              (stdout, ";; not our server:\n"),
                              ans, (resplen>anssiz)?anssiz:resplen);
                        goto wait;
                  }
#endif
                  if (!(_res.options & RES_INSECURE2) &&
                      !res_queriesmatch(buf, buf + buflen,
                                    ans, ans + anssiz)) {
                        /*
                         * response contains wrong query? ignore it.
                         * XXX - potential security hazard could
                         *     be detected here.
                         */
                        DprintQ((_res.options & RES_DEBUG) ||
                              (_res.pfcode & RES_PRF_REPLY),
                              (stdout, ";; wrong query name:\n"),
                              ans, (resplen>anssiz)?anssiz:resplen);
                        goto wait;
                  }
                  if (anhp->rcode == SERVFAIL ||
                      anhp->rcode == NOTIMP ||
                      anhp->rcode == REFUSED) {
                        DprintQ(_res.options & RES_DEBUG,
                              (stdout, "server rejected query:\n"),
                              ans, (resplen>anssiz)?anssiz:resplen);
                        badns |= (1 << ns);
                        _res_close();
                        /* don't retry if called from dig */
                        if (!_res.pfcode)
                              goto next_ns;
                  }
                  if (!(_res.options & RES_IGNTC) && anhp->tc) {
                        /*
                         * get rest of answer;
                         * use TCP with same server.
                         */
                        Dprint(_res.options & RES_DEBUG,
                               (stdout, ";; truncated answer\n"));
                        v_circuit = 1;
                        _res_close();
                        goto same_ns;
                  }
            } /*if vc/dg*/
            Dprint((_res.options & RES_DEBUG) ||
                   ((_res.pfcode & RES_PRF_REPLY) &&
                  (_res.pfcode & RES_PRF_HEAD1)),
                   (stdout, ";; got answer:\n"));
            DprintQ((_res.options & RES_DEBUG) ||
                  (_res.pfcode & RES_PRF_REPLY),
                  (stdout, ""),
                  ans, (resplen>anssiz)?anssiz:resplen);
            /*
             * If using virtual circuits, we assume that the first server
             * is preferred over the rest (i.e. it is on the local
             * machine) and only keep that one open.
             * If we have temporarily opened a virtual circuit,
             * or if we haven't been asked to keep a socket open,
             * close the socket.
             */
            if ((v_circuit && (!(_res.options & RES_USEVC) || ns != 0)) ||
                !(_res.options & RES_STAYOPEN)) {
                  _res_close();
            }
            if (Rhook) {
                  int done = 0, loops = 0;

                  do {
                        res_sendhookact act;

                        act = (*Rhook)(nsap, buf, buflen,
                                     ans, anssiz, &resplen);
                        switch (act) {
                        case res_goahead:
                        case res_done:
                              done = 1;
                              break;
                        case res_nextns:
                              _res_close();
                              goto next_ns;
                        case res_modified:
                              /* give the hook another try */
                              if (++loops < 42) /*doug adams*/
                                    break;
                              /*FALLTHROUGH*/
                        case res_error:
                              /*FALLTHROUGH*/
                        default:
                              return (-1);
                        }
                  } while (!done);

            }
            return (resplen);
    next_ns: ;
         } /*foreach ns*/
      } /*foreach retry*/
      _res_close();
      if (!v_circuit)
            if (!gotsomewhere)
                  errno = ECONNREFUSED;   /* no nameservers found */
            else
                  errno = ETIMEDOUT;      /* no answer obtained */
      else
            errno = terrno;
      return (-1);
}

/*
 * This routine is for closing the socket if a virtual circuit is used and
 * the program wants to close it.  This provides support for endhostent()
 * which expects to close the socket.
 *
 * This routine is not expected to be user visible.
 */
void
_res_close()
{
      if (s >= 0) {
            (void) close(s);
            s = -1;
            connected = 0;
            vc = 0;
      }
}

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