Annotation of 43BSDTahoe/lib/libc/net/res_init.c, revision 1.1.1.1

1.1       root        1: /*
                      2:  * Copyright (c) 1985 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 6.9 (Berkeley) 6/27/88";
                     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 configuration file. Contains the address of the
                     31:  * inital name server to query and the default domain for
                     32:  * non fully qualified domain names.
                     33:  */
                     34: 
                     35: #ifndef        CONFFILE
                     36: #define        CONFFILE        "/etc/resolv.conf"
                     37: #endif
                     38: 
                     39: /*
                     40:  * Resolver state default settings
                     41:  */
                     42: 
                     43: struct state _res = {
                     44:     RES_TIMEOUT,                       /* retransmition time interval */
                     45:     4,                                 /* number of times to retransmit */
                     46:     RES_DEFAULT,               /* options flags */
                     47:     1,                                 /* number of name servers */
                     48: };
                     49: 
                     50: /*
                     51:  * Set up default settings.  If the configuration file exist, the values
                     52:  * there will have precedence.  Otherwise, the server address is set to
                     53:  * INADDR_ANY and the default domain name comes from the gethostname().
                     54:  *
                     55:  * The configuration file should only be used if you want to redefine your
                     56:  * domain or run without a server on your machine.
                     57:  *
                     58:  * Return 0 if completes successfully, -1 on error
                     59:  */
                     60: res_init()
                     61: {
                     62:     register FILE *fp;
                     63:     register char *cp, **pp;
                     64:     char buf[BUFSIZ];
                     65:     extern u_long inet_addr();
                     66:     extern char *index();
                     67:     extern char *strcpy(), *strncpy();
                     68:     extern char *getenv();
                     69:     int n = 0;    /* number of nameserver records read from file */
                     70: 
                     71:     _res.nsaddr.sin_addr.s_addr = INADDR_ANY;
                     72:     _res.nsaddr.sin_family = AF_INET;
                     73:     _res.nsaddr.sin_port = htons(NAMESERVER_PORT);
                     74:     _res.nscount = 1;
                     75:     _res.defdname[0] = '\0';
                     76: 
                     77:     if ((fp = fopen(CONFFILE, "r")) != NULL) {
                     78:         /* read the config file */
                     79:         while (fgets(buf, sizeof(buf), fp) != NULL) {
                     80:             /* read default domain name */
                     81:             if (!strncmp(buf, "domain", sizeof("domain") - 1)) {
                     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));
                     88:                 _res.defdname[sizeof(_res.defdname) - 1] = '\0';
                     89:                 if ((cp = index(_res.defdname, '\n')) != NULL)
                     90:                     *cp = '\0';
                     91:                 continue;
                     92:             }
                     93:             /* read nameservers to query */
                     94:             if (!strncmp(buf, "nameserver", 
                     95:                sizeof("nameserver") - 1) && (n < MAXNS)) {
                     96:                 cp = buf + sizeof("nameserver") - 1;
                     97:                 while (*cp == ' ' || *cp == '\t')
                     98:                     cp++;
                     99:                 if (*cp == '\0')
                    100:                     continue;
                    101:                 _res.nsaddr_list[n].sin_addr.s_addr = inet_addr(cp);
                    102:                 if (_res.nsaddr_list[n].sin_addr.s_addr == (unsigned)-1) 
                    103:                     _res.nsaddr_list[n].sin_addr.s_addr = INADDR_ANY;
                    104:                 _res.nsaddr_list[n].sin_family = AF_INET;
                    105:                 _res.nsaddr_list[n].sin_port = htons(NAMESERVER_PORT);
                    106:                 if ( ++n >= MAXNS) { 
                    107:                     n = MAXNS;
                    108: #ifdef DEBUG
                    109:                     if ( _res.options & RES_DEBUG )
                    110:                         printf("MAXNS reached, reading resolv.conf\n");
                    111: #endif DEBUG
                    112:                 }
                    113:                 continue;
                    114:             }
                    115:         }
                    116:         if ( n > 1 ) 
                    117:             _res.nscount = n;
                    118:         (void) fclose(fp);
                    119:     }
                    120:     if (_res.defdname[0] == 0) {
                    121:         if (gethostname(buf, sizeof(_res.defdname)) == 0 &&
                    122:            (cp = index(buf, '.')))
                    123:              (void)strcpy(_res.defdname, cp + 1);
                    124:     }
                    125: 
                    126:     /* Allow user to override the local domain definition */
                    127:     if ((cp = getenv("LOCALDOMAIN")) != NULL)
                    128:         (void)strncpy(_res.defdname, cp, sizeof(_res.defdname));
                    129: 
                    130:     /* find components of local domain that might be searched */
                    131:     pp = _res.dnsrch;
                    132:     *pp++ = _res.defdname;
                    133:     for (cp = _res.defdname, n = 0; *cp; cp++)
                    134:        if (*cp == '.')
                    135:            n++;
                    136:     cp = _res.defdname;
                    137:     for (; n >= LOCALDOMAINPARTS && pp < _res.dnsrch + MAXDNSRCH; n--) {
                    138:        cp = index(cp, '.');
                    139:        *pp++ = ++cp;
                    140:     }
                    141:     _res.options |= RES_INIT;
                    142:     return(0);
                    143: }

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