RCSID updates, warning fixes

[dfdiff.git] / contrib / dhcp-3.0 / minires / res_send.c

/*
 * 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.
 */

/*
 * Portions Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
 * Portions Copyright (c) 1996-2003 by Internet Software Consortium
 *
 * 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.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC 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.
 *
 *   Internet Systems Consortium, Inc.
 *   950 Charter Street
 *   Redwood City, CA 94063
 *   <info@isc.org>
 *   http://www.isc.org/
 */

#if defined(LIBC_SCCS) && !defined(lint)
static const char sccsid[] = "@(#)res_send.c    8.1 (Berkeley) 6/4/93";
static const char rcsid[] = "$Id: res_send.c,v 1.7.2.2 2004/06/10 17:59:44 dhankins Exp $";
#endif /* LIBC_SCCS and not lint */

/* Rename the I/O functions in case we're tracing. */
#define send            trace_mr_send
#define recvfrom        trace_mr_recvfrom
#define read            trace_mr_read
#define connect         trace_mr_connect
#define socket          trace_mr_socket
#define bind            trace_mr_bind
#define close           trace_mr_close
#define select          trace_mr_select
#define time            trace_mr_time

/*
 * 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>
#include <sys/uio.h>

#include <netinet/in.h>
#include <arpa/inet.h>

#include <errno.h>
#include <netdb.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "minires/minires.h"
#include "arpa/nameser.h"

#define CHECK_SRVR_ADDR
                
static int cmpsock(struct sockaddr_in *a1, struct sockaddr_in *a2);
void res_pquery(const res_state, const u_char *, int, FILE *);

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

        ina = *inp;
        for (ns = 0;  ns < statp->nscount;  ns++) {
                const struct sockaddr_in *srv = &statp->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))
                        return (1);
        }
        return (0);
}

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

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

                n = dn_expand(buf, eom, cp, tname, sizeof tname);
                if (n < 0)
                        return (-1);
                cp += n;
                if (cp + 2 * INT16SZ > eom)
                        return (-1);
                ttype = getUShort(cp); cp += INT16SZ;
                tclass = getUShort(cp); cp += INT16SZ;
                if (ttype == type && tclass == class &&
                    ns_samename(tname, name) == 1)
                        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(const u_char *buf1, const u_char *eom1,
                 const u_char *buf2, const u_char *eom2)
{
        const u_char *cp = buf1 + HFIXEDSZ;
        int qdcount = ntohs(((const HEADER *)buf1)->qdcount);

        if (buf1 + HFIXEDSZ > eom1 || buf2 + HFIXEDSZ > eom2)
                return (-1);

        /*
         * Only header section present in replies to
         * dynamic update packets.
         */
        if ( (((const HEADER *)buf1)->opcode == ns_o_update) &&
             (((const HEADER *)buf2)->opcode == ns_o_update) )
                return (1);

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

                n = dn_expand(buf1, eom1, cp, tname, sizeof tname);
                if (n < 0)
                        return (-1);
                cp += n;
                if (cp + 2 * INT16SZ > eom1)
                        return (-1);
                ttype = getUShort(cp);  cp += INT16SZ;
                tclass = getUShort(cp); cp += INT16SZ;
                if (!res_nameinquery(tname, ttype, tclass, buf2, eom2))
                        return (0);
        }
        return (1);
}

isc_result_t
res_nsend(res_state statp,
          double *buf, unsigned buflen,
          double *ans, unsigned anssiz, unsigned *ansret)
{
        HEADER *hp = (HEADER *) buf;
        HEADER *anhp = (HEADER *) ans;
        int gotsomewhere, connreset, terrno, try, v_circuit, resplen, ns, n;
        u_int badns;    /* XXX NSMAX can't exceed #/bits in this variable */
        static int highestFD = FD_SETSIZE - 1;

        if (anssiz < HFIXEDSZ) {
                return ISC_R_INVALIDARG;
        }
        DprintQ((statp->options & RES_DEBUG) ||
                (statp->pfcode & RES_PRF_QUERY),
                (stdout, ";; res_send()\n"), buf, buflen);
        v_circuit = (statp->options & RES_USEVC) || buflen > PACKETSZ;
        gotsomewhere = 0;
        connreset = 0;
        terrno = ISC_R_TIMEDOUT;
        badns = 0;

        /*
         * Some callers want to even out the load on their resolver list.
         */
        if (statp->nscount > 0 && (statp->options & RES_ROTATE) != 0) {
                struct sockaddr_in ina;
                int lastns = statp->nscount - 1;

                ina = statp->nsaddr_list[0];
                for (ns = 0; ns < lastns; ns++)
                        statp->nsaddr_list[ns] = statp->nsaddr_list[ns + 1];
                statp->nsaddr_list[lastns] = ina;
        }

#if defined (TRACING)
        trace_mr_statp_setup (statp);
#endif

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

                if (statp->qhook) {
                        int done = 0, loops = 0;

                        do {
                                res_sendhookact act;

                                act = (*statp->qhook)(&nsap, &buf, &buflen,
                                                      ans, anssiz, &resplen);
                                switch (act) {
                                case res_goahead:
                                        done = 1;
                                        break;
                                case res_nextns:
                                        res_nclose(statp);
                                        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 ISC_R_UNEXPECTED;
                                }
                        } while (!done);
                }

                Dprint(statp->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 VC; at most one attempt per server. */
                        try = statp->retry;
                        truncated = 0;

                        /* Are we still talking to whom we want to talk to? */
                        if (statp->_sock >= 0 &&
                            (statp->_flags & RES_F_VC) != 0) {
                                struct sockaddr_in peer;
                                SOCKLEN_T size = sizeof(peer);

                                if (getpeername(statp->_sock,
                                                (struct sockaddr *)&peer,
                                                &size) < 0) {
                                        res_nclose(statp);
                                        statp->_flags &= ~RES_F_VC;
                                } else if (!cmpsock(&peer, nsap)) {
                                        res_nclose(statp);
                                        statp->_flags &= ~RES_F_VC;
                                }
                        }

                        if (statp->_sock < 0 ||
                            (statp->_flags & RES_F_VC) == 0) {
                                if (statp->_sock >= 0)
                                        res_nclose(statp);

                                statp->_sock = socket(PF_INET,
                                                       SOCK_STREAM, 0);
                                if (statp->_sock < 0 ||
                                    statp->_sock > highestFD) {
                                        terrno = uerr2isc (errno);
                                        Perror(statp, stderr,
                                               "socket(vc)", errno);
                                        return (-1);
                                }
                                errno = 0;
                                if (connect(statp->_sock,
                                            (struct sockaddr *)nsap,
                                            sizeof *nsap) < 0) {
                                        terrno = uerr2isc (errno);
                                        Aerror(statp, stderr, "connect/vc",
                                               errno, *nsap);
                                        badns |= (1 << ns);
                                        res_nclose(statp);
                                        goto next_ns;
                                }
                                statp->_flags |= RES_F_VC;
                        }
                        /*
                         * Send length & message
                         */
                        putUShort((u_char*)&len, buflen);
                        iov[0].iov_base = (caddr_t)&len;
                        iov[0].iov_len = INT16SZ;
                        iov[1].iov_base = (const caddr_t)buf;
                        iov[1].iov_len = buflen;
                        if (writev(statp->_sock, iov, 2) !=
                            (INT16SZ + buflen)) {
                                terrno = uerr2isc (errno);
                                Perror(statp, stderr, "write failed", errno);
                                badns |= (1 << ns);
                                res_nclose(statp);
                                goto next_ns;
                        }
                        /*
                         * Receive length & response
                         */
 read_len:
                        cp = (u_char *)ans;
                        len = INT16SZ;
                        while ((n = read(statp->_sock,
                                         (char *)cp, (unsigned)len)) > 0) {
                                cp += n;
                                if ((len -= n) <= 0)
                                        break;
                        }
                        if (n <= 0) {
                                terrno = uerr2isc (errno);
                                Perror(statp, stderr, "read failed", errno);
                                res_nclose(statp);
                                /*
                                 * 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 == ISC_R_CONNREFUSED &&
                                    !connreset) {
                                        connreset = 1;
                                        res_nclose(statp);
                                        goto same_ns;
                                }
                                res_nclose(statp);
                                goto next_ns;
                        }
                        resplen = getUShort ((unsigned char *)ans);
                        if (resplen > anssiz) {
                                Dprint(statp->options & RES_DEBUG,
                                       (stdout, ";; response truncated\n")
                                       );
                                truncated = 1;
                                len = anssiz;
                        } else
                                len = resplen;
                        if (len < HFIXEDSZ) {
                                /*
                                 * Undersized message.
                                 */
                                Dprint(statp->options & RES_DEBUG,
                                       (stdout, ";; undersized: %d\n", len));
                                terrno = ISC_R_NOSPACE;
                                badns |= (1 << ns);
                                res_nclose(statp);
                                goto next_ns;
                        }
                        cp = (u_char *)ans;
                        while (len != 0 &&
                               (n = read(statp->_sock,
                                         (char *)cp, (unsigned)len))
                               > 0) {
                                cp += n;
                                len -= n;
                        }
                        if (n <= 0) {
                                terrno = uerr2isc (errno);
                                Perror(statp, stderr, "read(vc)", errno);
                                res_nclose(statp);
                                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);
                                        n = read(statp->_sock,
                                                 junk, (unsigned)n);
                                        if (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((statp->options & RES_DEBUG) ||
                                        (statp->pfcode & RES_PRF_REPLY),
                                        (stdout,
                                         ";; old answer (unexpected):\n"),
                                        ans, (resplen>anssiz)?anssiz:resplen);
                                goto read_len;
                        }
                } else {
                        /*
                         * Use datagrams.
                         */
                        int start, timeout, finish;
                        fd_set dsmask;
                        struct sockaddr_in from;
                        SOCKLEN_T fromlen;
                        int seconds;

                        if (statp->_sock < 0 ||
                            (statp->_flags & RES_F_VC) != 0) {
                                if ((statp->_flags & RES_F_VC) != 0)
                                        res_nclose(statp);
                                statp->_sock = socket(PF_INET, SOCK_DGRAM, 0);
                                if (statp->_sock < 0 ||
                                    statp->_sock > highestFD) {
#ifndef CAN_RECONNECT
 bad_dg_sock:
#endif
                                        terrno = uerr2isc (errno);
                                        Perror(statp, stderr,
                                               "socket(dg)", errno);
                                        return terrno;
                                }
                                statp->_flags &= ~RES_F_CONN;
                        }
#ifndef CANNOT_CONNECT_DGRAM
                        /*
                         * 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 (statp->nscount == 1 || (try == 0 && ns == 0)) {
                                /*
                                 * Connect only if we are sure we won't
                                 * receive a response from another server.
                                 */
                                if ((statp->_flags & RES_F_CONN) == 0) {
                                        if (connect(statp->_sock,
                                                    (struct sockaddr *)nsap,
                                                    sizeof *nsap) < 0) {
                                                Aerror(statp, stderr,
                                                       "connect(dg)",
                                                       errno, *nsap);
                                                badns |= (1 << ns);
                                                res_nclose(statp);
                                                goto next_ns;
                                        }
                                        statp->_flags |= RES_F_CONN;
                                }
                              if (send(statp->_sock,
                                       (const char*)buf, (unsigned)buflen, 0)
                                  != buflen) {
                                        Perror(statp, stderr, "send", errno);
                                        badns |= (1 << ns);
                                        res_nclose(statp);
                                        goto next_ns;
                                }
                        } else {
                                /*
                                 * Disconnect if we want to listen
                                 * for responses from more than one server.
                                 */
                                if ((statp->_flags & RES_F_CONN) != 0) {
#ifdef 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(statp->_sock,
                                                       (struct sockaddr *)
                                                        &no_addr,
                                                       sizeof no_addr);
#else
                                        struct sockaddr_in local_addr;
                                        SOCKLEN_T len;
                                        int result, s1;

                                        len = sizeof(local_addr);
                                        s1 = socket(PF_INET, SOCK_DGRAM, 0);
                                        result = getsockname(statp->_sock,
                                                (struct sockaddr *)&local_addr,
                                                             &len);
                                        if (s1 < 0)
                                                goto bad_dg_sock;
                                        (void) dup2(s1, statp->_sock);
                                        (void) close(s1);
                                        if (result == 0) {
                                                /*
                                                 * Attempt to rebind to old
                                                 * port.  Note connected socket
                                                 * has an sin_addr set.
                                                 */
                                                local_addr.sin_addr.s_addr =
                                                        htonl(0);
                                                (void)bind(statp->_sock,
                                                           (struct sockaddr *)
                                                           &local_addr,
                                                           (unsigned)len);
                                        }
                                        Dprint(statp->options & RES_DEBUG,
                                               (stdout, ";; new DG socket\n"));
#endif /* CAN_RECONNECT */
                                        statp->_flags &= ~RES_F_CONN;
                                        errno = 0;
                                }
#endif /* !CANNOT_CONNECT_DGRAM */
                                if (sendto(statp->_sock,
                                           (const char *)buf, buflen, 0,
                                           (struct sockaddr *)nsap,
                                           sizeof *nsap)
                                    != buflen) {
                                        Aerror(statp, stderr, "sendto", errno, *nsap);
                                        badns |= (1 << ns);
                                        res_nclose(statp);
                                        goto next_ns;
                                }
#ifndef CANNOT_CONNECT_DGRAM
                        }
#endif /* !CANNOT_CONNECT_DGRAM */

                        if (statp->_sock < 0 || statp->_sock > highestFD) {
                                Perror(statp, stderr,
                                       "fd out-of-bounds", EMFILE);
                                res_nclose(statp);
                                goto next_ns;
                        }

                        /*
                         * Wait for reply
                         */
                        seconds = (statp->retrans << try);
                        if (try > 0)
                                seconds /= statp->nscount;
                        if (seconds <= 0)
                                seconds = 1;
                        start = cur_time;
                        timeout = seconds;
                        finish = start + timeout;
 wait:
                        FD_ZERO(&dsmask);
                        FD_SET(statp->_sock, &dsmask);
                        {
                                struct timeval t;
                                t.tv_sec = timeout;
                                t.tv_usec = 0;
                                n = select(statp->_sock + 1,
                                           &dsmask, NULL, NULL, &t);
                        }
                        if (n == 0) {
                                Dprint(statp->options & RES_DEBUG,
                                       (stdout, ";; timeout\n"));
                                gotsomewhere = 1;
                                goto next_ns;
                        }
                        if (n < 0) {
                                if (errno == EINTR) {
                                        if (finish >= cur_time) {
                                                timeout = finish - cur_time;
                                                goto wait;
                                        }
                                }
                                Perror(statp, stderr, "select", errno);
                                res_nclose(statp);
                                goto next_ns;
                        }
                        errno = 0;
                        fromlen = sizeof(struct sockaddr_in);
                        resplen = recvfrom(statp->_sock,
                                           (char *)ans, anssiz, 0,
                                           (struct sockaddr *)&from, &fromlen);
                        if (resplen <= 0) {
                                Perror(statp, stderr, "recvfrom", errno);
                                res_nclose(statp);
                                goto next_ns;
                        }
                        gotsomewhere = 1;
                        if (resplen < HFIXEDSZ) {
                                /*
                                 * Undersized message.
                                 */
                                Dprint(statp->options & RES_DEBUG,
                                       (stdout, ";; undersized: %d\n",
                                        resplen));
                                terrno = ISC_R_NOSPACE;
                                badns |= (1 << ns);
                                res_nclose(statp);
                                goto next_ns;
                        }
                        if (hp->id != anhp->id) {
                                /*
                                 * response from old query, ignore it.
                                 * XXX - potential security hazard could
                                 *       be detected here.
                                 */
                                DprintQ((statp->options & RES_DEBUG) ||
                                        (statp->pfcode & RES_PRF_REPLY),
                                        (stdout, ";; old answer:\n"),
                                        ans, (resplen>anssiz)?anssiz:resplen);
                                goto wait;
                        }
#ifdef CHECK_SRVR_ADDR
                        if (!(statp->options & RES_INSECURE1) &&
                            !res_ourserver_p(statp, &from)) {
                                /*
                                 * response from wrong server? ignore it.
                                 * XXX - potential security hazard could
                                 *       be detected here.
                                 */
                                DprintQ((statp->options & RES_DEBUG) ||
                                        (statp->pfcode & RES_PRF_REPLY),
                                        (stdout, ";; not our server:\n"),
                                        ans, (resplen>anssiz)?anssiz:resplen);
                                goto wait;
                        }
#endif
                        if (!(statp->options & RES_INSECURE2) &&
                            !res_queriesmatch((u_char *)buf,
                                              ((u_char *)buf) + buflen,
                                              (u_char *)ans,
                                              ((u_char *)ans) + anssiz)) {
                                /*
                                 * response contains wrong query? ignore it.
                                 * XXX - potential security hazard could
                                 *       be detected here.
                                 */
                                DprintQ((statp->options & RES_DEBUG) ||
                                        (statp->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(statp->options & RES_DEBUG,
                                        (stdout, "server rejected query:\n"),
                                        ans, (resplen>anssiz)?anssiz:resplen);
                                badns |= (1 << ns);
                                res_nclose(statp);
                                /* don't retry if called from dig */
                                if (!statp->pfcode)
                                        goto next_ns;
                        }
                        if (!(statp->options & RES_IGNTC) && anhp->tc) {
                                /*
                                 * get rest of answer;
                                 * use TCP with same server.
                                 */
                                Dprint(statp->options & RES_DEBUG,
                                       (stdout, ";; truncated answer\n"));
                                v_circuit = 1;
                                res_nclose(statp);
                                goto same_ns;
                        }
                } /*if vc/dg*/
                Dprint((statp->options & RES_DEBUG) ||
                       ((statp->pfcode & RES_PRF_REPLY) &&
                        (statp->pfcode & RES_PRF_HEAD1)),
                       (stdout, ";; got answer:\n"));
                DprintQ((statp->options & RES_DEBUG) ||
                        (statp->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 && (!(statp->options & RES_USEVC) || ns != 0)) ||
                    !(statp->options & RES_STAYOPEN)) {
                        res_nclose(statp);
                }
                if (statp->rhook) {
                        int done = 0, loops = 0;

                        do {
                                res_sendhookact act;

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

                }
                *ansret = resplen;
                return ISC_R_SUCCESS;
 next_ns: ;
           } /*foreach ns*/
        } /*foreach retry*/
        res_nclose(statp);
        if (!v_circuit) {
                if (!gotsomewhere)
                        terrno = ISC_R_CONNREFUSED;  /* no nameservers found */
                else
                        errno = ISC_R_TIMEDOUT; /* no answer obtained */
        }
        return terrno;
}

/*
 * 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_nclose(res_state statp) {
        if (statp->_sock >= 0) {
                (void) close(statp->_sock);
                statp->_sock = -1;
                statp->_flags &= ~(RES_F_VC | RES_F_CONN);
        }
}

/* Private */
static int
cmpsock(struct sockaddr_in *a1, struct sockaddr_in *a2) {
        return ((a1->sin_family == a2->sin_family) &&
                (a1->sin_port == a2->sin_port) &&
                (a1->sin_addr.s_addr == a2->sin_addr.s_addr));
}

#ifdef NEED_PSELECT
/* XXX needs to move to the porting library. */
static int
pselect(int nfds, void *rfds, void *wfds, void *efds,
        struct timespec *tsp,
        const sigset_t *sigmask)
{
        struct timeval tv, *tvp;
        sigset_t sigs;
        int n;

        if (tsp) {
                tvp = &tv;
                tv = evTimeVal(*tsp);
        } else
                tvp = NULL;
        if (sigmask)
                sigprocmask(SIG_SETMASK, sigmask, &sigs);
        n = select(nfds, rfds, wfds, efds, tvp);
        if (sigmask)
                sigprocmask(SIG_SETMASK, &sigs, NULL);
        if (tsp)
                *tsp = evTimeSpec(tv);
        return (n);
}
#endif