1 /*-
2 * Copyright (c) 1985, 1989, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * %sccs.include.redist.c%
6 * -
7 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
8 *
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, and that
12 * the name of Digital Equipment Corporation not be used in advertising or
13 * publicity pertaining to distribution of the document or software without
14 * specific, written prior permission.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
17 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT
19 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
20 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
21 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
22 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
23 * SOFTWARE.
24 * -
25 * --Copyright--
26 */
27
28 #if defined(LIBC_SCCS) && !defined(lint)
29 static char sccsid[] = "@(#)res_init.c 8.1 (Berkeley) 06/07/93";
30 static char rcsid[] = "$Id: res_init.c,v 4.9.1.1 1993/05/02 22:43:03 vixie Rel $";
31 #endif /* LIBC_SCCS and not lint */
32
33 #include <sys/param.h>
34 #include <sys/socket.h>
35 #include <netinet/in.h>
36 #include <arpa/inet.h>
37 #include <arpa/nameser.h>
38 #include <resolv.h>
39 #include <unistd.h>
40 #include <stdio.h>
41 #include <stdlib.h>
42 #include <string.h>
43
44 /*
45 * Resolver state default settings
46 */
47
48 struct __res_state _res = {
49 RES_TIMEOUT, /* retransmition time interval */
50 4, /* number of times to retransmit */
51 RES_DEFAULT, /* options flags */
52 1, /* number of name servers */
53 };
54
55 /*
56 * Set up default settings. If the configuration file exist, the values
57 * there will have precedence. Otherwise, the server address is set to
58 * INADDR_ANY and the default domain name comes from the gethostname().
59 *
60 * The configuration file should only be used if you want to redefine your
61 * domain or run without a server on your machine.
62 *
63 * Return 0 if completes successfully, -1 on error
64 */
res_init()65 res_init()
66 {
67 register FILE *fp;
68 register char *cp, **pp;
69 register int n;
70 char buf[BUFSIZ];
71 int nserv = 0; /* number of nameserver records read from file */
72 int haveenv = 0;
73 int havesearch = 0;
74
75 #ifdef USELOOPBACK
76 _res.nsaddr.sin_addr = inet_makeaddr(IN_LOOPBACKNET, 1);
77 #else
78 _res.nsaddr.sin_addr.s_addr = INADDR_ANY;
79 #endif
80 _res.nsaddr.sin_family = AF_INET;
81 _res.nsaddr.sin_port = htons(NAMESERVER_PORT);
82 _res.nscount = 1;
83 _res.pfcode = 0;
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 if ((cp = strpbrk(_res.defdname, " \t\n")) != NULL)
89 *cp = '\0';
90 haveenv++;
91 }
92
93 if ((fp = fopen(_PATH_RESCONF, "r")) != NULL) {
94 /* read the config file */
95 while (fgets(buf, sizeof(buf), fp) != NULL) {
96 /* skip comments */
97 if ((*buf == ';') || (*buf == '#'))
98 continue;
99 /* read default domain name */
100 if (!strncmp(buf, "domain", sizeof("domain") - 1)) {
101 if (haveenv) /* skip if have from environ */
102 continue;
103 cp = buf + sizeof("domain") - 1;
104 while (*cp == ' ' || *cp == '\t')
105 cp++;
106 if ((*cp == '\0') || (*cp == '\n'))
107 continue;
108 (void)strncpy(_res.defdname, cp,
109 sizeof(_res.defdname) - 1);
110 if ((cp = strpbrk(_res.defdname, " \t\n")) != NULL)
111 *cp = '\0';
112 havesearch = 0;
113 continue;
114 }
115 /* set search list */
116 if (!strncmp(buf, "search", sizeof("search") - 1)) {
117 if (haveenv) /* skip if have from environ */
118 continue;
119 cp = buf + sizeof("search") - 1;
120 while (*cp == ' ' || *cp == '\t')
121 cp++;
122 if ((*cp == '\0') || (*cp == '\n'))
123 continue;
124 (void)strncpy(_res.defdname, cp,
125 sizeof(_res.defdname) - 1);
126 if ((cp = strchr(_res.defdname, '\n')) != NULL)
127 *cp = '\0';
128 /*
129 * Set search list to be blank-separated strings
130 * on rest of line.
131 */
132 cp = _res.defdname;
133 pp = _res.dnsrch;
134 *pp++ = cp;
135 for (n = 0; *cp && pp < _res.dnsrch + MAXDNSRCH; cp++) {
136 if (*cp == ' ' || *cp == '\t') {
137 *cp = 0;
138 n = 1;
139 } else if (n) {
140 *pp++ = cp;
141 n = 0;
142 }
143 }
144 /* null terminate last domain if there are excess */
145 while (*cp != '\0' && *cp != ' ' && *cp != '\t')
146 cp++;
147 *cp = '\0';
148 *pp++ = 0;
149 havesearch = 1;
150 continue;
151 }
152 /* read nameservers to query */
153 if (!strncmp(buf, "nameserver", sizeof("nameserver") - 1) &&
154 nserv < MAXNS) {
155 struct in_addr a;
156
157 cp = buf + sizeof("nameserver") - 1;
158 while (*cp == ' ' || *cp == '\t')
159 cp++;
160 if ((*cp != '\0') && (*cp != '\n') && inet_aton(cp, &a)) {
161 _res.nsaddr_list[nserv].sin_addr = a;
162 _res.nsaddr_list[nserv].sin_family = AF_INET;
163 _res.nsaddr_list[nserv].sin_port =
164 htons(NAMESERVER_PORT);
165 nserv++;
166 }
167 continue;
168 }
169 }
170 if (nserv > 1)
171 _res.nscount = nserv;
172 (void) fclose(fp);
173 }
174 if (_res.defdname[0] == 0) {
175 if (gethostname(buf, sizeof(_res.defdname)) == 0 &&
176 (cp = strchr(buf, '.')))
177 (void)strcpy(_res.defdname, cp + 1);
178 }
179
180 /* find components of local domain that might be searched */
181 if (havesearch == 0) {
182 pp = _res.dnsrch;
183 *pp++ = _res.defdname;
184 for (cp = _res.defdname, n = 0; *cp; cp++)
185 if (*cp == '.')
186 n++;
187 cp = _res.defdname;
188 for (; n >= LOCALDOMAINPARTS && pp < _res.dnsrch + MAXDFLSRCH;
189 n--) {
190 cp = strchr(cp, '.');
191 *pp++ = ++cp;
192 }
193 *pp++ = 0;
194 }
195 _res.options |= RES_INIT;
196 return (0);
197 }
198