1 /*-
2 * Copyright (c) 1985, 1989 Regents of the University of California.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 * This product includes software developed by the University of
16 * California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34 #if defined(LIBC_SCCS) && !defined(lint)
35 static char sccsid[] = "@(#)res_init.c 6.15 (Berkeley) 2/24/91";
36 #endif /* LIBC_SCCS and not lint */
37
38 #include <sys/param.h>
39 #include <sys/socket.h>
40 #include <netinet/in.h>
41 #include <arpa/inet.h>
42 #include <arpa/nameser.h>
43 #include <resolv.h>
44 #include <unistd.h>
45 #include <stdio.h>
46 #include <stdlib.h>
47 #include <string.h>
48
49 /*
50 * Resolver state default settings
51 */
52
53 struct state _res = {
54 RES_TIMEOUT, /* retransmition time interval */
55 4, /* number of times to retransmit */
56 RES_DEFAULT, /* options flags */
57 1, /* number of name servers */
58 };
59
60 /*
61 * Set up default settings. If the configuration file exist, the values
62 * there will have precedence. Otherwise, the server address is set to
63 * INADDR_ANY and the default domain name comes from the gethostname().
64 *
65 * The configuration file should only be used if you want to redefine your
66 * domain or run without a server on your machine.
67 *
68 * Return 0 if completes successfully, -1 on error
69 */
res_init()70 res_init()
71 {
72 register FILE *fp;
73 register char *cp, **pp;
74 register int n;
75 char buf[BUFSIZ];
76 int nserv = 0; /* number of nameserver records read from file */
77 int haveenv = 0;
78 int havesearch = 0;
79
80 _res.nsaddr.sin_addr.s_addr = INADDR_ANY;
81 _res.nsaddr.sin_family = AF_INET;
82 _res.nsaddr.sin_port = htons(NAMESERVER_PORT);
83 _res.nscount = 1;
84
85 /* Allow user to override the local domain definition */
86 if ((cp = getenv("LOCALDOMAIN")) != NULL) {
87 (void)strncpy(_res.defdname, cp, sizeof(_res.defdname));
88 haveenv++;
89 }
90
91 if ((fp = fopen(_PATH_RESCONF, "r")) != NULL) {
92 /* read the config file */
93 while (fgets(buf, sizeof(buf), fp) != NULL) {
94 /* read default domain name */
95 if (!strncmp(buf, "domain", sizeof("domain") - 1)) {
96 if (haveenv) /* skip if have from environ */
97 continue;
98 cp = buf + sizeof("domain") - 1;
99 while (*cp == ' ' || *cp == '\t')
100 cp++;
101 if ((*cp == '\0') || (*cp == '\n'))
102 continue;
103 (void)strncpy(_res.defdname, cp, sizeof(_res.defdname) - 1);
104 if ((cp = index(_res.defdname, '\n')) != NULL)
105 *cp = '\0';
106 havesearch = 0;
107 continue;
108 }
109 /* set search list */
110 if (!strncmp(buf, "search", sizeof("search") - 1)) {
111 if (haveenv) /* skip if have from environ */
112 continue;
113 cp = buf + sizeof("search") - 1;
114 while (*cp == ' ' || *cp == '\t')
115 cp++;
116 if ((*cp == '\0') || (*cp == '\n'))
117 continue;
118 (void)strncpy(_res.defdname, cp, sizeof(_res.defdname) - 1);
119 if ((cp = index(_res.defdname, '\n')) != NULL)
120 *cp = '\0';
121 /*
122 * Set search list to be blank-separated strings
123 * on rest of line.
124 */
125 cp = _res.defdname;
126 pp = _res.dnsrch;
127 *pp++ = cp;
128 for (n = 0; *cp && pp < _res.dnsrch + MAXDNSRCH; cp++) {
129 if (*cp == ' ' || *cp == '\t') {
130 *cp = 0;
131 n = 1;
132 } else if (n) {
133 *pp++ = cp;
134 n = 0;
135 }
136 }
137 /* null terminate last domain if there are excess */
138 while (*cp != '\0' && *cp != ' ' && *cp != '\t')
139 cp++;
140 *cp = '\0';
141 *pp++ = 0;
142 havesearch = 1;
143 continue;
144 }
145 /* read nameservers to query */
146 if (!strncmp(buf, "nameserver", sizeof("nameserver") - 1) &&
147 nserv < MAXNS) {
148 cp = buf + sizeof("nameserver") - 1;
149 while (*cp == ' ' || *cp == '\t')
150 cp++;
151 if ((*cp == '\0') || (*cp == '\n'))
152 continue;
153 if ((_res.nsaddr_list[nserv].sin_addr.s_addr =
154 inet_addr(cp)) == (unsigned)-1) {
155 _res.nsaddr_list[nserv].sin_addr.s_addr
156 = INADDR_ANY;
157 continue;
158 }
159 _res.nsaddr_list[nserv].sin_family = AF_INET;
160 _res.nsaddr_list[nserv].sin_port = htons(NAMESERVER_PORT);
161 nserv++;
162 continue;
163 }
164 }
165 if (nserv > 1)
166 _res.nscount = nserv;
167 (void) fclose(fp);
168 }
169 if (_res.defdname[0] == 0) {
170 if (gethostname(buf, sizeof(_res.defdname)) == 0 &&
171 (cp = index(buf, '.')))
172 (void)strcpy(_res.defdname, cp + 1);
173 }
174
175 /* find components of local domain that might be searched */
176 if (havesearch == 0) {
177 pp = _res.dnsrch;
178 *pp++ = _res.defdname;
179 for (cp = _res.defdname, n = 0; *cp; cp++)
180 if (*cp == '.')
181 n++;
182 cp = _res.defdname;
183 for (; n >= LOCALDOMAINPARTS && pp < _res.dnsrch + MAXDFLSRCH;
184 n--) {
185 cp = index(cp, '.');
186 *pp++ = ++cp;
187 }
188 *pp++ = 0;
189 }
190 _res.options |= RES_INIT;
191 return (0);
192 }
193