lib/ip/res_init.c

   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 provided
   6  * that: (1) source distributions retain this entire copyright notice and
   7  * comment, and (2) distributions including binaries display the following
   8  * acknowledgement:  ``This product includes software developed by the
   9  * University of California, Berkeley and its contributors'' in the
  10  * documentation or other materials provided with the distribution and in
  11  * all advertising materials mentioning features or use of this software.
  12  * Neither the name of the University nor the names of its contributors may
  13  * be used to endorse or promote products derived from this software without
  14  * specific prior written permission.
  15  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
  16  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  17  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  18  */
  19
  20 #if defined(LIBC_SCCS) && !defined(lint)
  21 static char sccsid[] = "@(#)res_init.c  6.14 (Berkeley) 6/27/90";
  22 #endif /* LIBC_SCCS and not lint */
  23
  24 #if _MINIX
  25 #include <sys/types.h>
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28 #include <string.h>
  29 #include <unistd.h>
  30
  31 #include <net/hton.h>
  32 #include <net/gen/in.h>
  33 #include <net/gen/inet.h>
  34 #include <net/gen/nameser.h>
  35 #include <net/gen/netdb.h>
  36 #include <net/gen/resolv.h>
  37 #include <net/gen/socket.h>
  38
  39 #define index(s,c) strchr(s,c)
  40 #else
  41 #include <sys/types.h>
  42 #include <sys/socket.h>
  43 #include <netinet/in.h>
  44 #include <stdio.h>
  45 #include <arpa/nameser.h>
  46 #include <resolv.h>
  47 #endif
  48
  49 /*
  50  * Resolver state
  51  */
  52 struct state _res;
  53
  54 /*
  55  * Set up default settings.  If the configuration file exist, the values
  56  * there will have precedence.  Otherwise, the server address is set to
  57  * 127.0.0.1 (localhost) and the default domain name comes from gethostname().
  58  *
  59  * The configuration file should only be used if you want to redefine your
  60  * domain or run without a server on your machine.
  61  *
  62  * Return 0 if completes successfully, -1 on error
  63  */
  64 int
  65 res_init()
  66 {
  67         register FILE *fp;
  68         register char *cp, **pp;
  69         register int n;
  70         char buf[BUFSIZ];
  71         int haveenv = 0;
  72         int havesearch = 0;
  73         struct servent* servent;
  74         u16_t nameserver_port;
  75
  76         /* Resolver state default settings */
  77         _res.retrans = RES_TIMEOUT;     /* retransmition time interval */
  78         _res.retry = 4;                 /* number of times to retransmit */
  79         _res.options = RES_DEFAULT;     /* options flags */
  80         _res.nscount = 0;               /* number of name servers */
  81         _res.defdname[0] = 0;           /* domain */
  82
  83         servent= getservbyname("domain", NULL);
  84         if (!servent)
  85         {
  86                 h_errno= NO_RECOVERY;
  87                 return -1;
  88         }
  89         nameserver_port= servent->s_port;
  90
  91         /* Allow user to override the local domain definition */
  92         if ((cp = getenv("LOCALDOMAIN")) != NULL) {
  93                 (void)strncpy(_res.defdname, cp, sizeof(_res.defdname));
  94                 haveenv++;
  95         }
  96
  97         if ((fp = fopen(_PATH_RESCONF, "r")) != NULL) {
  98             /* read the config file */
  99             while (fgets(buf, sizeof(buf), fp) != NULL) {
 100                 /* read default domain name */
 101                 if (!strncmp(buf, "domain", sizeof("domain") - 1)) {
 102                     if (haveenv)        /* skip if have from environ */
 103                             continue;
 104                     cp = buf + sizeof("domain") - 1;
 105                     while (*cp == ' ' || *cp == '\t')
 106                             cp++;
 107                     if ((*cp == '\0') || (*cp == '\n'))
 108                             continue;
 109                     (void)strncpy(_res.defdname, cp, sizeof(_res.defdname) - 1);
 110                     if ((cp = index(_res.defdname, '\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, sizeof(_res.defdname) - 1);
 125                     if ((cp = index(_res.defdname, '\n')) != NULL)
 126                             *cp = '\0';
 127                     /*
 128                      * Set search list to be blank-separated strings
 129                      * on rest of line.
 130                      */
 131                     cp = _res.defdname;
 132                     pp = _res.dnsrch;
 133                     *pp++ = cp;
 134                     for (n = 0; *cp && pp < _res.dnsrch + MAXDNSRCH; cp++) {
 135                             if (*cp == ' ' || *cp == '\t') {
 136                                     *cp = 0;
 137                                     n = 1;
 138                             } else if (n) {
 139                                     *pp++ = cp;
 140                                     n = 0;
 141                             }
 142                     }
 143                     /* null terminate last domain if there are excess */
 144                     while (*cp != '\0' && *cp != ' ' && *cp != '\t')
 145                             cp++;
 146                     *cp = '\0';
 147                     *pp++ = 0;
 148                     havesearch = 1;
 149                     continue;
 150                 }
 151                 /* read nameservers to query */
 152                 if (!strncmp(buf, "nameserver", sizeof("nameserver") - 1) &&
 153                    _res.nscount < MAXNS) {
 154                     cp = buf + sizeof("nameserver") - 1;
 155                     while (*cp == ' ' || *cp == '\t')
 156                             cp++;
 157                     if ((*cp == '\0') || (*cp == '\n'))
 158                             continue;
 159                     if (!inet_aton(cp, &_res.nsaddr_list[_res.nscount]))
 160                             continue;
 161                     _res.nsport_list[_res.nscount]= nameserver_port;
 162                     _res.nscount++;
 163                     continue;
 164                 }
 165             }
 166             (void) fclose(fp);
 167         }
 168         if (_res.nscount == 0) {
 169                 /* "localhost" is the default nameserver. */
 170                 _res.nsaddr_list[0]= HTONL(0x7F000001);
 171                 _res.nsport_list[0]= nameserver_port;
 172                 _res.nscount= 1;
 173         }
 174         if (_res.defdname[0] == 0) {
 175                 if (gethostname(buf, sizeof(_res.defdname)) == 0 &&
 176                    (cp = index(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 = index(cp, '.');
 191                         *pp++ = ++cp;
 192                 }
 193                 *pp++ = 0;
 194         }
 195         _res.options |= RES_INIT;
 196         return (0);
 197 }