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