493 lines
14 KiB
C
493 lines
14 KiB
C
/*-
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* SPDX-License-Identifier: (ISC AND BSD-3-Clause)
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*
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* Portions Copyright (C) 2004, 2005, 2008 Internet Systems Consortium, Inc. ("ISC")
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* Portions Copyright (C) 1996-2001, 2003 Internet Software Consortium.
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
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* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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* AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
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* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
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* OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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* PERFORMANCE OF THIS SOFTWARE.
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*/
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/*
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* Copyright (c) 1988, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* Portions Copyright (c) 1993 by Digital Equipment Corporation.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies, and that
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* the name of Digital Equipment Corporation not be used in advertising or
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* publicity pertaining to distribution of the document or software without
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* specific, written prior permission.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
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* WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT
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* CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
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* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
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* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
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* ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
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* SOFTWARE.
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*/
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#if defined(LIBC_SCCS) && !defined(lint)
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static const char sccsid[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93";
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static const char rcsid[] = "$Id: res_query.c,v 1.11 2008/11/14 02:36:51 marka Exp $";
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#endif /* LIBC_SCCS and not lint */
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "port_before.h"
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#include <sys/param.h>
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#include <arpa/nameser.h>
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#include <ctype.h>
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#include <errno.h>
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#include <netdb.h>
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#include <resolv.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "port_after.h"
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/* Options. Leave them on. */
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#ifndef DEBUG
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#define DEBUG
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#endif
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#if PACKETSZ > 1024
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#define MAXPACKET PACKETSZ
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#else
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#define MAXPACKET 1024
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#endif
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/*%
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* Formulate a normal query, send, and await answer.
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* Returned answer is placed in supplied buffer "answer".
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* Perform preliminary check of answer, returning success only
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* if no error is indicated and the answer count is nonzero.
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* Return the size of the response on success, -1 on error.
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* Error number is left in H_ERRNO.
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*
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* Caller must parse answer and determine whether it answers the question.
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*/
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int
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res_nquery(res_state statp,
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const char *name, /*%< domain name */
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int class, int type, /*%< class and type of query */
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u_char *answer, /*%< buffer to put answer */
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int anslen) /*%< size of answer buffer */
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{
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u_char buf[MAXPACKET];
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HEADER *hp = (HEADER *) answer;
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u_int oflags;
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u_char *rdata;
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int n;
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oflags = statp->_flags;
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again:
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hp->rcode = NOERROR; /*%< default */
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#ifdef DEBUG
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if (statp->options & RES_DEBUG)
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printf(";; res_query(%s, %d, %d)\n", name, class, type);
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#endif
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n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
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buf, sizeof(buf));
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#ifdef RES_USE_EDNS0
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if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 &&
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(statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC|RES_NSID))) {
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n = res_nopt(statp, n, buf, sizeof(buf), anslen);
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if (n > 0 && (statp->options & RES_NSID) != 0U) {
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rdata = &buf[n];
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n = res_nopt_rdata(statp, n, buf, sizeof(buf), rdata,
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NS_OPT_NSID, 0, NULL);
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}
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}
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#endif
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if (n <= 0) {
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#ifdef DEBUG
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if (statp->options & RES_DEBUG)
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printf(";; res_query: mkquery failed\n");
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#endif
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RES_SET_H_ERRNO(statp, NO_RECOVERY);
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return (n);
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}
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n = res_nsend(statp, buf, n, answer, anslen);
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if (n < 0) {
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#ifdef RES_USE_EDNS0
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/* if the query choked with EDNS0, retry without EDNS0 */
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if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U &&
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((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) {
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statp->_flags |= RES_F_EDNS0ERR;
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if (statp->options & RES_DEBUG)
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printf(";; res_nquery: retry without EDNS0\n");
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goto again;
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}
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#endif
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#ifdef DEBUG
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if (statp->options & RES_DEBUG)
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printf(";; res_query: send error\n");
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#endif
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RES_SET_H_ERRNO(statp, TRY_AGAIN);
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return (n);
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}
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if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
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#ifdef DEBUG
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if (statp->options & RES_DEBUG)
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printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n",
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p_rcode(hp->rcode),
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ntohs(hp->ancount),
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ntohs(hp->nscount),
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ntohs(hp->arcount));
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#endif
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switch (hp->rcode) {
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case NXDOMAIN:
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RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
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break;
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case SERVFAIL:
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RES_SET_H_ERRNO(statp, TRY_AGAIN);
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break;
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case NOERROR:
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RES_SET_H_ERRNO(statp, NO_DATA);
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break;
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case FORMERR:
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case NOTIMP:
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case REFUSED:
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default:
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RES_SET_H_ERRNO(statp, NO_RECOVERY);
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break;
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}
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return (-1);
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}
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return (n);
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}
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/*%
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* Formulate a normal query, send, and retrieve answer in supplied buffer.
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* Return the size of the response on success, -1 on error.
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* If enabled, implement search rules until answer or unrecoverable failure
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* is detected. Error code, if any, is left in H_ERRNO.
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*/
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int
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res_nsearch(res_state statp,
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const char *name, /*%< domain name */
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int class, int type, /*%< class and type of query */
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u_char *answer, /*%< buffer to put answer */
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int anslen) /*%< size of answer */
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{
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const char *cp, * const *domain;
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HEADER *hp = (HEADER *) answer;
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char tmp[NS_MAXDNAME];
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u_int dots;
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int trailing_dot, ret, saved_herrno;
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int got_nodata = 0, got_servfail = 0, root_on_list = 0;
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int tried_as_is = 0;
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int searched = 0;
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errno = 0;
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RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /*%< True if we never query. */
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dots = 0;
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for (cp = name; *cp != '\0'; cp++)
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dots += (*cp == '.');
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trailing_dot = 0;
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if (cp > name && *--cp == '.')
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trailing_dot++;
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/* If there aren't any dots, it could be a user-level alias. */
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if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
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return (res_nquery(statp, cp, class, type, answer, anslen));
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/*
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* If there are enough dots in the name, let's just give it a
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* try 'as is'. The threshold can be set with the "ndots" option.
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* Also, query 'as is', if there is a trailing dot in the name.
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*/
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saved_herrno = -1;
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if (dots >= statp->ndots || trailing_dot) {
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ret = res_nquerydomain(statp, name, NULL, class, type,
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answer, anslen);
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if (ret > 0 || trailing_dot)
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return (ret);
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if (errno == ECONNREFUSED) {
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RES_SET_H_ERRNO(statp, TRY_AGAIN);
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return (-1);
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}
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switch (statp->res_h_errno) {
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case NO_DATA:
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case HOST_NOT_FOUND:
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break;
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case TRY_AGAIN:
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if (hp->rcode == SERVFAIL)
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break;
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/* FALLTHROUGH */
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default:
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return (-1);
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}
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saved_herrno = statp->res_h_errno;
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tried_as_is++;
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}
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/*
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* We do at least one level of search if
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* - there is no dot and RES_DEFNAME is set, or
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* - there is at least one dot, there is no trailing dot,
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* and RES_DNSRCH is set.
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*/
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if ((!dots && (statp->options & RES_DEFNAMES) != 0U) ||
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(dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) {
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int done = 0;
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for (domain = (const char * const *)statp->dnsrch;
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*domain && !done;
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domain++) {
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searched = 1;
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if (domain[0][0] == '\0' ||
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(domain[0][0] == '.' && domain[0][1] == '\0'))
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root_on_list++;
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if (root_on_list && tried_as_is)
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continue;
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ret = res_nquerydomain(statp, name, *domain,
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class, type,
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answer, anslen);
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if (ret > 0)
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return (ret);
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/*
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* If no server present, give up.
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* If name isn't found in this domain,
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* keep trying higher domains in the search list
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* (if that's enabled).
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* On a NO_DATA error, keep trying, otherwise
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* a wildcard entry of another type could keep us
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* from finding this entry higher in the domain.
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* If we get some other error (negative answer or
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* server failure), then stop searching up,
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* but try the input name below in case it's
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* fully-qualified.
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*/
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if (errno == ECONNREFUSED) {
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RES_SET_H_ERRNO(statp, TRY_AGAIN);
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return (-1);
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}
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switch (statp->res_h_errno) {
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case NO_DATA:
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got_nodata++;
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/* FALLTHROUGH */
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case HOST_NOT_FOUND:
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/* keep trying */
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break;
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case TRY_AGAIN:
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/*
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* This can occur due to a server failure
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* (that is, all listed servers have failed),
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* or all listed servers have timed out.
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* ((HEADER *)answer)->rcode may not be set
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* to SERVFAIL in the case of a timeout.
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*
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* Either way we must return TRY_AGAIN in
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* order to avoid non-deterministic
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* return codes.
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* For example, loaded name servers or races
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* against network startup/validation (dhcp,
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* ppp, etc) can cause the search to timeout
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* on one search element, e.g. 'fu.bar.com',
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* and return a definitive failure on the
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* next search element, e.g. 'fu.'.
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*/
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got_servfail++;
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if (hp->rcode == SERVFAIL) {
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/* try next search element, if any */
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break;
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}
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/* FALLTHROUGH */
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default:
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/* anything else implies that we're done */
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done++;
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}
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/* if we got here for some reason other than DNSRCH,
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* we only wanted one iteration of the loop, so stop.
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*/
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if ((statp->options & RES_DNSRCH) == 0U)
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done++;
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}
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}
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switch (statp->res_h_errno) {
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case NO_DATA:
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case HOST_NOT_FOUND:
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break;
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case TRY_AGAIN:
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if (hp->rcode == SERVFAIL)
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break;
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/* FALLTHROUGH */
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default:
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goto giveup;
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}
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/*
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* If the query has not already been tried as is then try it
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* unless RES_NOTLDQUERY is set and there were no dots.
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*/
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if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) &&
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!(tried_as_is || root_on_list)) {
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ret = res_nquerydomain(statp, name, NULL, class, type,
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answer, anslen);
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if (ret > 0)
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return (ret);
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}
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/* if we got here, we didn't satisfy the search.
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* if we did an initial full query, return that query's H_ERRNO
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* (note that we wouldn't be here if that query had succeeded).
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* else if we ever got a nodata, send that back as the reason.
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* else send back meaningless H_ERRNO, that being the one from
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* the last DNSRCH we did.
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*/
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giveup:
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if (saved_herrno != -1)
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RES_SET_H_ERRNO(statp, saved_herrno);
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else if (got_nodata)
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RES_SET_H_ERRNO(statp, NO_DATA);
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else if (got_servfail)
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RES_SET_H_ERRNO(statp, TRY_AGAIN);
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return (-1);
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}
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/*%
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* Perform a call on res_query on the concatenation of name and domain,
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* removing a trailing dot from name if domain is NULL.
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*/
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int
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res_nquerydomain(res_state statp,
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const char *name,
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const char *domain,
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int class, int type, /*%< class and type of query */
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u_char *answer, /*%< buffer to put answer */
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int anslen) /*%< size of answer */
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{
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char nbuf[MAXDNAME];
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const char *longname = nbuf;
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int n, d;
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#ifdef DEBUG
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if (statp->options & RES_DEBUG)
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printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
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name, domain?domain:"<Nil>", class, type);
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#endif
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if (domain == NULL) {
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/*
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* Check for trailing '.';
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* copy without '.' if present.
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*/
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n = strlen(name);
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if (n >= MAXDNAME) {
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RES_SET_H_ERRNO(statp, NO_RECOVERY);
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return (-1);
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}
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n--;
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if (n >= 0 && name[n] == '.') {
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strncpy(nbuf, name, n);
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nbuf[n] = '\0';
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} else
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longname = name;
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} else {
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n = strlen(name);
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d = strlen(domain);
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if (n + d + 1 >= MAXDNAME) {
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RES_SET_H_ERRNO(statp, NO_RECOVERY);
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return (-1);
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}
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sprintf(nbuf, "%s.%s", name, domain);
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}
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return (res_nquery(statp, longname, class, type, answer, anslen));
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}
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const char *
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res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {
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char *file, *cp1, *cp2;
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char buf[BUFSIZ];
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FILE *fp;
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if (statp->options & RES_NOALIASES)
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return (NULL);
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if (issetugid())
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return (NULL);
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file = getenv("HOSTALIASES");
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if (file == NULL || (fp = fopen(file, "re")) == NULL)
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return (NULL);
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setbuf(fp, NULL);
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buf[sizeof(buf) - 1] = '\0';
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while (fgets(buf, sizeof(buf), fp)) {
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for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1)
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;
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if (!*cp1)
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break;
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*cp1 = '\0';
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if (ns_samename(buf, name) == 1) {
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while (isspace((unsigned char)*++cp1))
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;
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if (!*cp1)
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break;
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for (cp2 = cp1 + 1; *cp2 &&
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!isspace((unsigned char)*cp2); ++cp2)
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;
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*cp2 = '\0';
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strncpy(dst, cp1, siz - 1);
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dst[siz - 1] = '\0';
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fclose(fp);
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return (dst);
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}
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}
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fclose(fp);
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return (NULL);
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}
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/*! \file */
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