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e6b4e2de6d
Many callers of __res_maybe_init also call _res_hconf_init. Additional calls to the latter do not hurt because the function does its work only once. (/etc/hosts.conf is not reloaded or even checked for changes.) This means that we can simplify the code by calling _res_hconf_init directly from __res_vinit.
553 lines
19 KiB
C
553 lines
19 KiB
C
/* Resolver state initialization and resolv.conf parsing.
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Copyright (C) 1995-2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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/*
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* Copyright (c) 1985, 1989, 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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* 4. 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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/*
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* Portions Copyright (c) 1996-1999 by Internet Software Consortium.
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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.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
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* ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
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* CONSORTIUM 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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#include <ctype.h>
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#include <netdb.h>
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#include <resolv/resolv-internal.h>
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#include <res_hconf.h>
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#include <stdio.h>
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#include <stdio_ext.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 <stdint.h>
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#include <arpa/inet.h>
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#include <arpa/nameser.h>
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#include <net/if.h>
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#include <netinet/in.h>
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#include <sys/param.h>
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#include <sys/socket.h>
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#include <sys/time.h>
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#include <sys/types.h>
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#include <inet/net-internal.h>
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#include <errno.h>
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static void res_setoptions (res_state, const char *, const char *);
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static uint32_t net_mask (struct in_addr);
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unsigned long long int __res_initstamp;
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int
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res_ninit (res_state statp)
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{
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return __res_vinit (statp, 0);
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}
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libc_hidden_def (__res_ninit)
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/* Return true if CH separates the netmask in the "sortlist"
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directive. */
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static inline bool
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is_sort_mask (char ch)
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{
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return ch == '/' || ch == '&';
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}
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/* Internal helper function for __res_vinit, to aid with resource
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deallocation and error handling. Return true on success, false on
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failure. */
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static bool
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res_vinit_1 (res_state statp, bool preinit, FILE *fp, char **buffer)
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{
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char *cp, **pp;
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size_t buffer_size = 0;
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int nserv = 0; /* Number of nameservers read from file. */
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bool have_serv6 = false;
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bool haveenv = false;
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bool havesearch = false;
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int nsort = 0;
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char *net;
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statp->_u._ext.initstamp = __res_initstamp;
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if (!preinit)
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{
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statp->retrans = RES_TIMEOUT;
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statp->retry = RES_DFLRETRY;
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statp->options = RES_DEFAULT;
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statp->id = res_randomid ();
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}
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statp->nscount = 0;
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statp->defdname[0] = '\0';
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statp->ndots = 1;
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statp->pfcode = 0;
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statp->_vcsock = -1;
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statp->_flags = 0;
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statp->__glibc_unused_qhook = NULL;
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statp->__glibc_unused_rhook = NULL;
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statp->_u._ext.nscount = 0;
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for (int n = 0; n < MAXNS; n++)
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statp->_u._ext.nsaddrs[n] = NULL;
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/* Allow user to override the local domain definition. */
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if ((cp = getenv ("LOCALDOMAIN")) != NULL)
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{
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strncpy (statp->defdname, cp, sizeof (statp->defdname) - 1);
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statp->defdname[sizeof (statp->defdname) - 1] = '\0';
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haveenv = true;
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/* Set search list to be blank-separated strings from rest of
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env value. Permits users of LOCALDOMAIN to still have a
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search list, and anyone to set the one that they want to use
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as an individual (even more important now that the rfc1535
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stuff restricts searches). */
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cp = statp->defdname;
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pp = statp->dnsrch;
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*pp++ = cp;
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for (int n = 0; *cp && pp < statp->dnsrch + MAXDNSRCH; cp++)
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{
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if (*cp == '\n')
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break;
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else if (*cp == ' ' || *cp == '\t')
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{
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*cp = 0;
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n = 1;
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}
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else if (n > 0)
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{
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*pp++ = cp;
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n = 0;
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havesearch = true;
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}
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}
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/* Null terminate last domain if there are excess. */
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while (*cp != '\0' && *cp != ' ' && *cp != '\t' && *cp != '\n')
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cp++;
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*cp = '\0';
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*pp++ = 0;
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}
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#define MATCH(line, name) \
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(!strncmp ((line), name, sizeof (name) - 1) \
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&& ((line)[sizeof (name) - 1] == ' ' \
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|| (line)[sizeof (name) - 1] == '\t'))
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if (fp != NULL)
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{
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/* No threads use this stream. */
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__fsetlocking (fp, FSETLOCKING_BYCALLER);
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/* Read the config file. */
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while (true)
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{
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{
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ssize_t ret = __getline (buffer, &buffer_size, fp);
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if (ret <= 0)
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{
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if (_IO_ferror_unlocked (fp))
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return false;
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else
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break;
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}
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}
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/* Skip comments. */
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if (**buffer == ';' || **buffer == '#')
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continue;
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/* Read default domain name. */
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if (MATCH (*buffer, "domain"))
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{
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if (haveenv)
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/* LOCALDOMAIN overrides the configuration file. */
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continue;
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cp = *buffer + sizeof ("domain") - 1;
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while (*cp == ' ' || *cp == '\t')
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cp++;
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if ((*cp == '\0') || (*cp == '\n'))
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continue;
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strncpy (statp->defdname, cp, sizeof (statp->defdname) - 1);
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statp->defdname[sizeof (statp->defdname) - 1] = '\0';
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if ((cp = strpbrk (statp->defdname, " \t\n")) != NULL)
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*cp = '\0';
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havesearch = false;
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continue;
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}
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/* Set search list. */
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if (MATCH (*buffer, "search"))
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{
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if (haveenv)
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/* LOCALDOMAIN overrides the configuration file. */
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continue;
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cp = *buffer + sizeof ("search") - 1;
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while (*cp == ' ' || *cp == '\t')
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cp++;
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if ((*cp == '\0') || (*cp == '\n'))
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continue;
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strncpy (statp->defdname, cp, sizeof (statp->defdname) - 1);
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statp->defdname[sizeof (statp->defdname) - 1] = '\0';
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if ((cp = strchr (statp->defdname, '\n')) != NULL)
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*cp = '\0';
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/* Set search list to be blank-separated strings on rest
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of line. */
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cp = statp->defdname;
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pp = statp->dnsrch;
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*pp++ = cp;
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for (int n = 0; *cp && pp < statp->dnsrch + MAXDNSRCH; cp++)
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{
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if (*cp == ' ' || *cp == '\t')
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{
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*cp = 0;
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n = 1;
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}
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else if (n)
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{
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*pp++ = cp;
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n = 0;
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}
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}
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/* Null terminate last domain if there are excess. */
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while (*cp != '\0' && *cp != ' ' && *cp != '\t')
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cp++;
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*cp = '\0';
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*pp++ = 0;
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havesearch = true;
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continue;
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}
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/* Read nameservers to query. */
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if (MATCH (*buffer, "nameserver") && nserv < MAXNS)
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{
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struct in_addr a;
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cp = *buffer + sizeof ("nameserver") - 1;
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while (*cp == ' ' || *cp == '\t')
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cp++;
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if ((*cp != '\0') && (*cp != '\n') && __inet_aton (cp, &a))
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{
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statp->nsaddr_list[nserv].sin_addr = a;
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statp->nsaddr_list[nserv].sin_family = AF_INET;
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statp->nsaddr_list[nserv].sin_port = htons (NAMESERVER_PORT);
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nserv++;
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}
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else
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{
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struct in6_addr a6;
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char *el;
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if ((el = strpbrk (cp, " \t\n")) != NULL)
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*el = '\0';
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if ((el = strchr (cp, SCOPE_DELIMITER)) != NULL)
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*el = '\0';
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if ((*cp != '\0') && (__inet_pton (AF_INET6, cp, &a6) > 0))
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{
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struct sockaddr_in6 *sa6;
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sa6 = malloc (sizeof (*sa6));
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if (sa6 == NULL)
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return false;
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sa6->sin6_family = AF_INET6;
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sa6->sin6_port = htons (NAMESERVER_PORT);
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sa6->sin6_flowinfo = 0;
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sa6->sin6_addr = a6;
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sa6->sin6_scope_id = 0;
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if (__glibc_likely (el != NULL))
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/* Ignore errors, for backwards
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compatibility. */
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__inet6_scopeid_pton
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(&a6, el + 1, &sa6->sin6_scope_id);
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statp->nsaddr_list[nserv].sin_family = 0;
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statp->_u._ext.nsaddrs[nserv] = sa6;
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statp->_u._ext.nssocks[nserv] = -1;
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have_serv6 = true;
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nserv++;
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}
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}
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continue;
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}
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if (MATCH (*buffer, "sortlist"))
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{
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struct in_addr a;
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cp = *buffer + sizeof ("sortlist") - 1;
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while (nsort < MAXRESOLVSORT)
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{
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while (*cp == ' ' || *cp == '\t')
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cp++;
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if (*cp == '\0' || *cp == '\n' || *cp == ';')
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break;
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net = cp;
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while (*cp && !is_sort_mask (*cp) && *cp != ';'
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&& isascii (*cp) && !isspace (*cp))
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cp++;
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char separator = *cp;
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*cp = 0;
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if (__inet_aton (net, &a))
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{
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statp->sort_list[nsort].addr = a;
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if (is_sort_mask (separator))
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{
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*cp++ = separator;
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net = cp;
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while (*cp && *cp != ';'
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&& isascii (*cp) && !isspace (*cp))
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cp++;
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separator = *cp;
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*cp = 0;
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if (__inet_aton (net, &a))
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statp->sort_list[nsort].mask = a.s_addr;
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else
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statp->sort_list[nsort].mask
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= net_mask (statp->sort_list[nsort].addr);
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}
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else
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statp->sort_list[nsort].mask
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= net_mask (statp->sort_list[nsort].addr);
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nsort++;
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}
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*cp = separator;
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}
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continue;
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}
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if (MATCH (*buffer, "options"))
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{
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res_setoptions (statp, *buffer + sizeof ("options") - 1, "conf");
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continue;
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}
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}
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statp->nscount = nserv;
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if (have_serv6)
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/* We try IPv6 servers again. */
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statp->ipv6_unavail = false;
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statp->nsort = nsort;
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fclose (fp);
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}
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if (__glibc_unlikely (statp->nscount == 0))
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{
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statp->nsaddr.sin_addr = __inet_makeaddr (IN_LOOPBACKNET, 1);
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statp->nsaddr.sin_family = AF_INET;
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statp->nsaddr.sin_port = htons (NAMESERVER_PORT);
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statp->nscount = 1;
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}
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if (statp->defdname[0] == 0)
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{
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char buf[sizeof (statp->defdname)];
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if (__gethostname (buf, sizeof (statp->defdname) - 1) == 0
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&& (cp = strchr (buf, '.')) != NULL)
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strcpy (statp->defdname, cp + 1);
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}
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/* Find components of local domain that might be searched. */
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if (!havesearch)
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{
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pp = statp->dnsrch;
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*pp++ = statp->defdname;
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*pp = NULL;
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}
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if ((cp = getenv ("RES_OPTIONS")) != NULL)
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res_setoptions (statp, cp, "env");
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statp->options |= RES_INIT;
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return true;
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}
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/* Set up default settings. If the /etc/resolv.conf configuration
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file exist, the values there will have precedence. Otherwise, the
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server address is set to INADDR_LOOPBACK and the default domain
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name comes from gethostname. The RES_OPTIONS and LOCALDOMAIN
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environment variables can be used to override some settings.
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Return 0 if completes successfully, -1 on error. */
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int
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__res_vinit (res_state statp, int preinit)
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{
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/* Ensure that /etc/hosts.conf has been loaded (once). */
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_res_hconf_init ();
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FILE *fp = fopen (_PATH_RESCONF, "rce");
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if (fp == NULL)
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switch (errno)
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{
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case EACCES:
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case EISDIR:
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case ELOOP:
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case ENOENT:
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case ENOTDIR:
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case EPERM:
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/* Ignore these errors. They are persistent errors caused
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by file system contents. */
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break;
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default:
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/* Other errors refer to resource allocation problems and
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need to be handled by the application. */
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return -1;
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}
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char *buffer = NULL;
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bool ok = res_vinit_1 (statp, preinit, fp, &buffer);
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free (buffer);
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if (!ok)
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{
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/* Deallocate the name server addresses which have been
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allocated. */
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for (int n = 0; n < MAXNS; n++)
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free (statp->_u._ext.nsaddrs[n]);
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return -1;
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}
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return 0;
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}
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static void
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res_setoptions (res_state statp, const char *options, const char *source)
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{
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const char *cp = options;
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while (*cp)
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{
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/* Skip leading and inner runs of spaces. */
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while (*cp == ' ' || *cp == '\t')
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cp++;
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/* Search for and process individual options. */
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if (!strncmp (cp, "ndots:", sizeof ("ndots:") - 1))
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{
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int i = atoi (cp + sizeof ("ndots:") - 1);
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if (i <= RES_MAXNDOTS)
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statp->ndots = i;
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else
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statp->ndots = RES_MAXNDOTS;
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}
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else if (!strncmp (cp, "timeout:", sizeof ("timeout:") - 1))
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{
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int i = atoi (cp + sizeof ("timeout:") - 1);
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if (i <= RES_MAXRETRANS)
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statp->retrans = i;
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else
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statp->retrans = RES_MAXRETRANS;
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}
|
|
else if (!strncmp (cp, "attempts:", sizeof ("attempts:") - 1))
|
|
{
|
|
int i = atoi (cp + sizeof ("attempts:") - 1);
|
|
if (i <= RES_MAXRETRY)
|
|
statp->retry = i;
|
|
else
|
|
statp->retry = RES_MAXRETRY;
|
|
}
|
|
else
|
|
{
|
|
static const struct
|
|
{
|
|
char str[22];
|
|
uint8_t len;
|
|
uint8_t clear;
|
|
unsigned long int flag;
|
|
} options[] = {
|
|
#define STRnLEN(str) str, sizeof (str) - 1
|
|
{ STRnLEN ("inet6"), 0, DEPRECATED_RES_USE_INET6 },
|
|
{ STRnLEN ("rotate"), 0, RES_ROTATE },
|
|
{ STRnLEN ("edns0"), 0, RES_USE_EDNS0 },
|
|
{ STRnLEN ("single-request-reopen"), 0, RES_SNGLKUPREOP },
|
|
{ STRnLEN ("single-request"), 0, RES_SNGLKUP },
|
|
{ STRnLEN ("no_tld_query"), 0, RES_NOTLDQUERY },
|
|
{ STRnLEN ("no-tld-query"), 0, RES_NOTLDQUERY },
|
|
{ STRnLEN ("use-vc"), 0, RES_USEVC }
|
|
};
|
|
#define noptions (sizeof (options) / sizeof (options[0]))
|
|
for (int i = 0; i < noptions; ++i)
|
|
if (strncmp (cp, options[i].str, options[i].len) == 0)
|
|
{
|
|
if (options[i].clear)
|
|
statp->options &= options[i].flag;
|
|
else
|
|
statp->options |= options[i].flag;
|
|
break;
|
|
}
|
|
}
|
|
/* Skip to next run of spaces. */
|
|
while (*cp && *cp != ' ' && *cp != '\t')
|
|
cp++;
|
|
}
|
|
}
|
|
|
|
static uint32_t
|
|
net_mask (struct in_addr in)
|
|
{
|
|
uint32_t i = ntohl (in.s_addr);
|
|
|
|
if (IN_CLASSA (i))
|
|
return htonl (IN_CLASSA_NET);
|
|
else if (IN_CLASSB (i))
|
|
return htonl (IN_CLASSB_NET);
|
|
return htonl (IN_CLASSC_NET);
|
|
}
|