usr/src/lib/libc/net/res_init.c

/*-
 * Copyright (c) 1985, 1989 Regents of the University of California.
 * All rights reserved.
 *
 * %sccs.include.redist.c%
 * -
 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies, and that
 * the name of Digital Equipment Corporation not be used in advertising or
 * publicity pertaining to distribution of the document or software without
 * specific, written prior permission.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
 * SOFTWARE.
 * -
 * --Copyright--
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)res_init.c  8.1 (Berkeley) %G%";
static char rcsid[] = "$Id: res_init.c,v 4.9.1.1 1993/05/02 22:43:03 vixie Rel $";
#endif /* LIBC_SCCS and not lint */

#include <sys/param.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>
#include <resolv.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/*
 * Resolver state default settings
 */

struct __res_state _res = {
        RES_TIMEOUT,                    /* retransmition time interval */
        4,                              /* number of times to retransmit */
        RES_DEFAULT,                    /* options flags */
        1,                              /* number of name servers */
};

/*
 * Set up default settings.  If the configuration file exist, the values
 * there will have precedence.  Otherwise, the server address is set to
 * INADDR_ANY and the default domain name comes from the gethostname().
 *
 * The configuration file should only be used if you want to redefine your
 * domain or run without a server on your machine.
 *
 * Return 0 if completes successfully, -1 on error
 */
res_init()
{
        register FILE *fp;
        register char *cp, **pp;
        register int n;
        char buf[BUFSIZ];
        int nserv = 0;    /* number of nameserver records read from file */
        int haveenv = 0;
        int havesearch = 0;

#ifdef USELOOPBACK
        _res.nsaddr.sin_addr = inet_makeaddr(IN_LOOPBACKNET, 1);
#else
        _res.nsaddr.sin_addr.s_addr = INADDR_ANY;
#endif
        _res.nsaddr.sin_family = AF_INET;
        _res.nsaddr.sin_port = htons(NAMESERVER_PORT);
        _res.nscount = 1;
        _res.pfcode = 0;

        /* Allow user to override the local domain definition */
        if ((cp = getenv("LOCALDOMAIN")) != NULL) {
                (void)strncpy(_res.defdname, cp, sizeof(_res.defdname));
                if ((cp = strpbrk(_res.defdname, " \t\n")) != NULL)
                        *cp = '\0';
                haveenv++;
        }

        if ((fp = fopen(_PATH_RESCONF, "r")) != NULL) {
            /* read the config file */
            while (fgets(buf, sizeof(buf), fp) != NULL) {
                /* skip comments */
                if ((*buf == ';') || (*buf == '#'))
                        continue;
                /* read default domain name */
                if (!strncmp(buf, "domain", sizeof("domain") - 1)) {
                    if (haveenv)        /* skip if have from environ */
                            continue;
                    cp = buf + sizeof("domain") - 1;
                    while (*cp == ' ' || *cp == '\t')
                            cp++;
                    if ((*cp == '\0') || (*cp == '\n'))
                            continue;
                    (void)strncpy(_res.defdname, cp,
                                  sizeof(_res.defdname) - 1);
                    if ((cp = strpbrk(_res.defdname, " \t\n")) != NULL)
                            *cp = '\0';
                    havesearch = 0;
                    continue;
                }
                /* set search list */
                if (!strncmp(buf, "search", sizeof("search") - 1)) {
                    if (haveenv)        /* skip if have from environ */
                            continue;
                    cp = buf + sizeof("search") - 1;
                    while (*cp == ' ' || *cp == '\t')
                            cp++;
                    if ((*cp == '\0') || (*cp == '\n'))
                            continue;
                    (void)strncpy(_res.defdname, cp,
                                  sizeof(_res.defdname) - 1);
                    if ((cp = index(_res.defdname, '\n')) != NULL)
                            *cp = '\0';
                    /*
                     * Set search list to be blank-separated strings
                     * on rest of line.
                     */
                    cp = _res.defdname;
                    pp = _res.dnsrch;
                    *pp++ = cp;
                    for (n = 0; *cp && pp < _res.dnsrch + MAXDNSRCH; cp++) {
                            if (*cp == ' ' || *cp == '\t') {
                                    *cp = 0;
                                    n = 1;
                            } else if (n) {
                                    *pp++ = cp;
                                    n = 0;
                            }
                    }
                    /* null terminate last domain if there are excess */
                    while (*cp != '\0' && *cp != ' ' && *cp != '\t')
                            cp++;
                    *cp = '\0';
                    *pp++ = 0;
                    havesearch = 1;
                    continue;
                }
                /* read nameservers to query */
                if (!strncmp(buf, "nameserver", sizeof("nameserver") - 1) &&
                   nserv < MAXNS) {
                   struct in_addr a;

                    cp = buf + sizeof("nameserver") - 1;
                    while (*cp == ' ' || *cp == '\t')
                        cp++;
                    if ((*cp != '\0') && (*cp != '\n') && inet_aton(cp, &a)) {
                        _res.nsaddr_list[nserv].sin_addr = a;
                        _res.nsaddr_list[nserv].sin_family = AF_INET;
                        _res.nsaddr_list[nserv].sin_port =
                                htons(NAMESERVER_PORT);
                        nserv++;
                    }
                    continue;
                }
            }
            if (nserv > 1)
                _res.nscount = nserv;
            (void) fclose(fp);
        }
        if (_res.defdname[0] == 0) {
                if (gethostname(buf, sizeof(_res.defdname)) == 0 &&
                   (cp = index(buf, '.')))
                        (void)strcpy(_res.defdname, cp + 1);
        }

        /* find components of local domain that might be searched */
        if (havesearch == 0) {
                pp = _res.dnsrch;
                *pp++ = _res.defdname;
                for (cp = _res.defdname, n = 0; *cp; cp++)
                        if (*cp == '.')
                                n++;
                cp = _res.defdname;
                for (; n >= LOCALDOMAINPARTS && pp < _res.dnsrch + MAXDFLSRCH;
                    n--) {
                        cp = index(cp, '.');
                        *pp++ = ++cp;
                }
                *pp++ = 0;
        }
        _res.options |= RES_INIT;
        return (0);
}