3 Parser for /etc/resolv.conf file. */
6 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
7 * Copyright (c) 1996-2003 by Internet Software Consortium
9 * Permission to use, copy, modify, and distribute this software for any
10 * purpose with or without fee is hereby granted, provided that the above
11 * copyright notice and this permission notice appear in all copies.
13 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
14 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
15 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
16 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
17 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
18 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
19 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
21 * Internet Systems Consortium, Inc.
23 * Redwood City, CA 94063
27 * This software has been written for Internet Systems Consortium
28 * by Ted Lemon in cooperation with Vixie Enterprises and Nominum, Inc.
29 * To learn more about Internet Systems Consortium, see
30 * ``http://www.isc.org/''. To learn more about Vixie Enterprises,
31 * see ``http://www.vix.com''. To learn more about Nominum, Inc., see
32 * ``http://www.nominum.com''.
36 static char copyright[] =
37 "$Id: resolv.c,v 1.16.2.2 2004/06/10 17:59:20 dhankins Exp $ Copyright (c) 2004 Internet Systems Consortium. All rights reserved.\n";
42 struct name_server *name_servers;
43 struct domain_search_list *domains;
44 char path_resolv_conf [] = _PATH_RESOLV_CONF;
46 void read_resolv_conf (parse_time)
54 struct name_server *sp, *sl, *ns;
55 struct domain_search_list *dp, *dl, *nd;
58 if ((file = open (path_resolv_conf, O_RDONLY)) < 0) {
59 log_error ("Can't open %s: %m", path_resolv_conf);
63 cfile = (struct parse *)0;
64 new_parse (&cfile, file, (char *)0, 0, path_resolv_conf, 1);
67 token = next_token (&val, (unsigned *)0, cfile);
68 if (token == END_OF_FILE)
70 else if (token == EOL)
72 else if (token == DOMAIN || token == SEARCH) {
74 struct domain_search_list *nd, **dp;
77 dn = parse_host_name (cfile);
82 for (nd = domains; nd; nd = nd -> next) {
84 if (!strcmp (nd -> domain, dn))
88 nd = new_domain_search_list (MDL);
90 log_fatal ("No memory for %s",
93 (struct domain_search_list *)0;
98 nd -> rcdate = parse_time;
99 token = peek_token (&val,
100 (unsigned *)0, cfile);
101 } while (token != EOL);
104 "junk after domain declaration");
105 skip_to_semi (cfile);
107 token = next_token (&val, (unsigned *)0, cfile);
108 } else if (token == NAMESERVER) {
109 struct name_server *ns, **sp;
112 parse_ip_addr (cfile, &iaddr);
115 for (ns = name_servers; ns; ns = ns -> next) {
117 if (!memcmp (&ns -> addr.sin_addr,
118 iaddr.iabuf, iaddr.len))
122 ns = new_name_server (MDL);
124 log_fatal ("No memory for nameserver %s",
126 ns -> next = (struct name_server *)0;
128 memcpy (&ns -> addr.sin_addr,
129 iaddr.iabuf, iaddr.len);
131 ns -> addr.sin_len = sizeof ns -> addr;
133 ns -> addr.sin_family = AF_INET;
134 ns -> addr.sin_port = htons (53);
135 memset (ns -> addr.sin_zero, 0,
136 sizeof ns -> addr.sin_zero);
138 ns -> rcdate = parse_time;
139 skip_to_semi (cfile);
141 skip_to_semi (cfile); /* Ignore what we don't grok. */
143 token = next_token (&val, (unsigned *)0, cfile);
145 /* Lose servers that are no longer in /etc/resolv.conf. */
146 sl = (struct name_server *)0;
147 for (sp = name_servers; sp; sp = ns) {
149 if (sp -> rcdate != parse_time) {
151 sl -> next = sp -> next;
153 name_servers = sp -> next;
154 /* We can't actually free the name server structure,
155 because somebody might be hanging on to it. If
156 your /etc/resolv.conf file changes a lot, this
157 could be a noticable memory leak. */
162 /* Lose domains that are no longer in /etc/resolv.conf. */
163 dl = (struct domain_search_list *)0;
164 for (dp = domains; dp; dp = nd) {
166 if (dp -> rcdate != parse_time) {
168 dl -> next = dp -> next;
170 domains = dp -> next;
171 free_domain_search_list (dp, MDL);
179 /* Pick a name server from the /etc/resolv.conf file. */
181 struct name_server *first_name_server ()
187 /* Check /etc/resolv.conf and reload it if it's changed. */
188 if (cur_time > rcdate) {
189 if (stat (path_resolv_conf, &st) < 0) {
190 log_error ("Can't stat %s", path_resolv_conf);
191 return (struct name_server *)0;
193 if (st.st_mtime > rcdate) {
196 rcdate = cur_time + 1;
198 read_resolv_conf (rcdate);