213 lines
6.1 KiB
C
213 lines
6.1 KiB
C
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/* resolv.c
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Parser for /etc/resolv.conf file. */
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/*
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* Copyright (c) 1996-2001 Internet Software Consortium.
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* 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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*
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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 Internet Software Consortium nor the names
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* of its contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
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* CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* 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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* This software has been written for the Internet Software Consortium
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* by Ted Lemon in cooperation with Vixie Enterprises and Nominum, Inc.
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* To learn more about the Internet Software Consortium, see
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* ``http://www.isc.org/''. To learn more about Vixie Enterprises,
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* see ``http://www.vix.com''. To learn more about Nominum, Inc., see
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* ``http://www.nominum.com''.
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*/
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#ifndef lint
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static char copyright[] =
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"$Id: resolv.c,v 1.16 2001/05/02 06:39:43 mellon Exp $ Copyright (c) 1996-2001 The Internet Software Consortium. All rights reserved.\n";
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#endif /* not lint */
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#include "dhcpd.h"
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struct name_server *name_servers;
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struct domain_search_list *domains;
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char path_resolv_conf [] = _PATH_RESOLV_CONF;
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void read_resolv_conf (parse_time)
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TIME parse_time;
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{
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int file;
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struct parse *cfile;
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const char *val;
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int token;
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int declaration = 0;
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struct name_server *sp, *sl, *ns;
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struct domain_search_list *dp, *dl, *nd;
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struct iaddr *iaddr;
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if ((file = open (path_resolv_conf, O_RDONLY)) < 0) {
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log_error ("Can't open %s: %m", path_resolv_conf);
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return;
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}
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cfile = (struct parse *)0;
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new_parse (&cfile, file, (char *)0, 0, path_resolv_conf, 1);
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do {
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token = next_token (&val, (unsigned *)0, cfile);
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if (token == END_OF_FILE)
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break;
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else if (token == EOL)
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continue;
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else if (token == DOMAIN || token == SEARCH) {
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do {
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struct domain_search_list *nd, **dp;
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char *dn;
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dn = parse_host_name (cfile);
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if (!dn)
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break;
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dp = &domains;
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for (nd = domains; nd; nd = nd -> next) {
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dp = &nd -> next;
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if (!strcmp (nd -> domain, dn))
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break;
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}
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if (!nd) {
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nd = new_domain_search_list (MDL);
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if (!nd)
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log_fatal ("No memory for %s",
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dn);
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nd -> next =
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(struct domain_search_list *)0;
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*dp = nd;
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nd -> domain = dn;
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dn = (char *)0;
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}
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nd -> rcdate = parse_time;
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token = peek_token (&val,
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(unsigned *)0, cfile);
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} while (token != EOL);
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if (token != EOL) {
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parse_warn (cfile,
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"junk after domain declaration");
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skip_to_semi (cfile);
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}
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token = next_token (&val, (unsigned *)0, cfile);
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} else if (token == NAMESERVER) {
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struct name_server *ns, **sp;
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struct iaddr iaddr;
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parse_ip_addr (cfile, &iaddr);
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sp = &name_servers;
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for (ns = name_servers; ns; ns = ns -> next) {
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sp = &ns -> next;
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if (!memcmp (&ns -> addr.sin_addr,
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iaddr.iabuf, iaddr.len))
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break;
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}
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if (!ns) {
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ns = new_name_server (MDL);
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if (!ns)
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log_fatal ("No memory for nameserver %s",
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piaddr (iaddr));
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ns -> next = (struct name_server *)0;
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*sp = ns;
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memcpy (&ns -> addr.sin_addr,
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iaddr.iabuf, iaddr.len);
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#ifdef HAVE_SA_LEN
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ns -> addr.sin_len = sizeof ns -> addr;
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#endif
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ns -> addr.sin_family = AF_INET;
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ns -> addr.sin_port = htons (53);
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memset (ns -> addr.sin_zero, 0,
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sizeof ns -> addr.sin_zero);
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}
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ns -> rcdate = parse_time;
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skip_to_semi (cfile);
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} else
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skip_to_semi (cfile); /* Ignore what we don't grok. */
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} while (1);
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token = next_token (&val, (unsigned *)0, cfile);
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/* Lose servers that are no longer in /etc/resolv.conf. */
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sl = (struct name_server *)0;
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for (sp = name_servers; sp; sp = ns) {
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ns = sp -> next;
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if (sp -> rcdate != parse_time) {
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if (sl)
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sl -> next = sp -> next;
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else
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name_servers = sp -> next;
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/* We can't actually free the name server structure,
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because somebody might be hanging on to it. If
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your /etc/resolv.conf file changes a lot, this
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could be a noticable memory leak. */
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} else
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sl = sp;
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}
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/* Lose domains that are no longer in /etc/resolv.conf. */
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dl = (struct domain_search_list *)0;
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for (dp = domains; dp; dp = nd) {
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nd = dp -> next;
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if (dp -> rcdate != parse_time) {
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if (dl)
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dl -> next = dp -> next;
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else
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domains = dp -> next;
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free_domain_search_list (dp, MDL);
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} else
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dl = dp;
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}
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close (file);
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end_parse (&cfile);
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}
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/* Pick a name server from the /etc/resolv.conf file. */
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struct name_server *first_name_server ()
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{
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FILE *rc;
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static TIME rcdate;
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struct stat st;
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/* Check /etc/resolv.conf and reload it if it's changed. */
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if (cur_time > rcdate) {
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if (stat (path_resolv_conf, &st) < 0) {
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log_error ("Can't stat %s", path_resolv_conf);
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return (struct name_server *)0;
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}
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if (st.st_mtime > rcdate) {
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char rcbuf [512];
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char *s, *t, *u;
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rcdate = cur_time + 1;
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read_resolv_conf (rcdate);
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}
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}
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return name_servers;
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}
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