| 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 are permitted |
| 6 | * provided that the above copyright notice and this paragraph are |
| 7 | * duplicated in all such forms and that any documentation, |
| 8 | * advertising materials, and other materials related to such |
| 9 | * distribution and use acknowledge that the software was developed |
| 10 | * by the University of California, Berkeley. The name of the |
| 11 | * University may not be used to endorse or promote products derived |
| 12 | * from this software without specific prior written permission. |
| 13 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR |
| 14 | * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED |
| 15 | * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. |
| 16 | */ |
| 17 | |
| 18 | #if defined(LIBC_SCCS) && !defined(lint) |
| 19 | static char sccsid[] = "@(#)res_init.c 6.11 (Berkeley) %G%"; |
| 20 | #endif /* LIBC_SCCS and not lint */ |
| 21 | |
| 22 | #include <sys/types.h> |
| 23 | #include <sys/socket.h> |
| 24 | #include <netinet/in.h> |
| 25 | #include <stdio.h> |
| 26 | #include <arpa/nameser.h> |
| 27 | #include <resolv.h> |
| 28 | |
| 29 | /* |
| 30 | * Resolver state default settings |
| 31 | */ |
| 32 | |
| 33 | struct state _res = { |
| 34 | RES_TIMEOUT, /* retransmition time interval */ |
| 35 | 4, /* number of times to retransmit */ |
| 36 | RES_DEFAULT, /* options flags */ |
| 37 | 1, /* number of name servers */ |
| 38 | }; |
| 39 | |
| 40 | /* |
| 41 | * Set up default settings. If the configuration file exist, the values |
| 42 | * there will have precedence. Otherwise, the server address is set to |
| 43 | * INADDR_ANY and the default domain name comes from the gethostname(). |
| 44 | * |
| 45 | * The configuration file should only be used if you want to redefine your |
| 46 | * domain or run without a server on your machine. |
| 47 | * |
| 48 | * Return 0 if completes successfully, -1 on error |
| 49 | */ |
| 50 | res_init() |
| 51 | { |
| 52 | register FILE *fp; |
| 53 | register char *cp, **pp; |
| 54 | register int n; |
| 55 | char buf[BUFSIZ]; |
| 56 | extern u_long inet_addr(); |
| 57 | extern char *index(); |
| 58 | extern char *strcpy(), *strncpy(); |
| 59 | extern char *getenv(); |
| 60 | int nserv = 0; /* number of nameserver records read from file */ |
| 61 | int haveenv = 0; |
| 62 | int havesearch = 0; |
| 63 | |
| 64 | _res.nsaddr.sin_addr.s_addr = INADDR_ANY; |
| 65 | _res.nsaddr.sin_family = AF_INET; |
| 66 | _res.nsaddr.sin_port = htons(NAMESERVER_PORT); |
| 67 | _res.nscount = 1; |
| 68 | |
| 69 | /* Allow user to override the local domain definition */ |
| 70 | if ((cp = getenv("LOCALDOMAIN")) != NULL) { |
| 71 | (void)strncpy(_res.defdname, cp, sizeof(_res.defdname)); |
| 72 | haveenv++; |
| 73 | } |
| 74 | |
| 75 | if ((fp = fopen(_PATH_RESCONF, "r")) != NULL) { |
| 76 | /* read the config file */ |
| 77 | while (fgets(buf, sizeof(buf), fp) != NULL) { |
| 78 | /* read default domain name */ |
| 79 | if (!strncmp(buf, "domain", sizeof("domain") - 1)) { |
| 80 | if (haveenv) /* skip if have from environ */ |
| 81 | continue; |
| 82 | cp = buf + sizeof("domain") - 1; |
| 83 | while (*cp == ' ' || *cp == '\t') |
| 84 | cp++; |
| 85 | if (*cp == '\0') |
| 86 | continue; |
| 87 | (void)strncpy(_res.defdname, cp, sizeof(_res.defdname) - 1); |
| 88 | if ((cp = index(_res.defdname, '\n')) != NULL) |
| 89 | *cp = '\0'; |
| 90 | havesearch = 0; |
| 91 | continue; |
| 92 | } |
| 93 | /* set search list */ |
| 94 | if (!strncmp(buf, "search", sizeof("search") - 1)) { |
| 95 | if (haveenv) /* skip if have from environ */ |
| 96 | continue; |
| 97 | cp = buf + sizeof("search") - 1; |
| 98 | while (*cp == ' ' || *cp == '\t') |
| 99 | cp++; |
| 100 | if (*cp == '\0') |
| 101 | continue; |
| 102 | (void)strncpy(_res.defdname, cp, sizeof(_res.defdname) - 1); |
| 103 | if ((cp = index(_res.defdname, '\n')) != NULL) |
| 104 | *cp = '\0'; |
| 105 | /* |
| 106 | * Set search list to be blank-separated strings |
| 107 | * on rest of line. |
| 108 | */ |
| 109 | cp = _res.defdname; |
| 110 | pp = _res.dnsrch; |
| 111 | *pp++ = cp; |
| 112 | for (n = 0; *cp && pp < _res.dnsrch + MAXDNSRCH; cp++) { |
| 113 | if (*cp == ' ' || *cp == '\t') { |
| 114 | *cp = 0; |
| 115 | n = 1; |
| 116 | } else if (n) { |
| 117 | *pp++ = cp; |
| 118 | n = 0; |
| 119 | } |
| 120 | } |
| 121 | *pp++ = 0; |
| 122 | havesearch = 1; |
| 123 | continue; |
| 124 | } |
| 125 | /* read nameservers to query */ |
| 126 | if (!strncmp(buf, "nameserver", sizeof("nameserver") - 1) && |
| 127 | nserv < MAXNS) { |
| 128 | cp = buf + sizeof("nameserver") - 1; |
| 129 | while (*cp == ' ' || *cp == '\t') |
| 130 | cp++; |
| 131 | if (*cp == '\0') |
| 132 | continue; |
| 133 | if ((_res.nsaddr_list[nserv].sin_addr.s_addr = |
| 134 | inet_addr(cp)) == (unsigned)-1) |
| 135 | continue; |
| 136 | _res.nsaddr_list[nserv].sin_family = AF_INET; |
| 137 | _res.nsaddr_list[nserv].sin_port = htons(NAMESERVER_PORT); |
| 138 | nserv++; |
| 139 | continue; |
| 140 | } |
| 141 | } |
| 142 | if (nserv > 1) |
| 143 | _res.nscount = nserv; |
| 144 | (void) fclose(fp); |
| 145 | } |
| 146 | if (_res.defdname[0] == 0) { |
| 147 | if (gethostname(buf, sizeof(_res.defdname)) == 0 && |
| 148 | (cp = index(buf, '.'))) |
| 149 | (void)strcpy(_res.defdname, cp + 1); |
| 150 | } |
| 151 | |
| 152 | /* find components of local domain that might be searched */ |
| 153 | if (havesearch == 0) { |
| 154 | pp = _res.dnsrch; |
| 155 | *pp++ = _res.defdname; |
| 156 | for (cp = _res.defdname, n = 0; *cp; cp++) |
| 157 | if (*cp == '.') |
| 158 | n++; |
| 159 | cp = _res.defdname; |
| 160 | for (; n >= LOCALDOMAINPARTS && pp < _res.dnsrch + MAXDFLSRCH; |
| 161 | n--) { |
| 162 | cp = index(cp, '.'); |
| 163 | *pp++ = ++cp; |
| 164 | } |
| 165 | *pp++ = 0; |
| 166 | } |
| 167 | _res.options |= RES_INIT; |
| 168 | return (0); |
| 169 | } |