/*
 * Copyright (c) 1985, 1989, 1993
 *    The Regents of the University of California.  All rights reserved.
 *
 * Portions copyright (c) 1999, 2000
 * Intel Corporation.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *
 *    This product includes software developed by the University of
 *    California, Berkeley, Intel Corporation, and its contributors.
 *
 * 4. Neither the name of University, Intel Corporation, or their respective
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS, INTEL CORPORATION AND
 * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS,
 * INTEL CORPORATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * 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.
 */

/*
 * Portions Copyright (c) 1996 by Internet Software Consortium.
 *
 * 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.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
 * CONSORTIUM 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.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)res_init.c  8.1 (Berkeley) 6/7/93";
static char orig_rcsid[] = "From: Id: res_init.c,v 8.7 1996/11/18 09:10:04 vixie Exp $";
static char rcsid[] = "$Id: res_init.c,v 1.1.1.1 2003/11/19 01:51:37 kyu3 Exp $";
#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>
#include <ctype.h>
#include <resolv.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "res_config.h"

static void res_setoptions __P((char *, char *));

#ifdef RESOLVSORT
static const char sort_mask[] = "/&";
#define ISSORTMASK(ch) (strchr(sort_mask, ch) != NULL)
static u_int32_t net_mask __P((struct in_addr));
#endif

#if !defined(isascii) /* XXX - could be a function */
# define isascii(c) (!(c & 0200))
#endif

/*
 * Resolver state default settings.
 */

struct __res_state _res
# if defined(__BIND_RES_TEXT)
    = { RES_TIMEOUT, }  /* Motorola, et al. */
# endif
    ;


/*
 * 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().
 *
 * An interrim version of this code (BIND 4.9, pre-4.4BSD) used 127.0.0.1
 * rather than INADDR_ANY ("0.0.0.0") as the default name server address
 * since it was noted that INADDR_ANY actually meant ``the first interface
 * you "ifconfig"'d at boot time'' and if this was a SLIP or PPP interface,
 * it had to be "up" in order for you to reach your own name server.  It
 * was later decided that since the recommended practice is to always
 * install local static routes through 127.0.0.1 for all your network
 * interfaces, that we could solve this problem without a code change.
 *
 * The configuration file should always be used, since it is the only way
 * to specify a default domain.  If you are running a server on your local
 * machine, you should say "nameserver 0.0.0.0" or "nameserver 127.0.0.1"
 * in the configuration file.
 *
 * Return 0 if completes successfully, -1 on error
 */
int
res_init()
{
    register FILE *fp;
    register char *cp, **pp;
    register int n;
    char buf[MAXDNAME];
    int nserv = 0;    /* number of nameserver records read from file */
    int haveenv = 0;
    int havesearch = 0;
#ifdef RESOLVSORT
    int nsort = 0;
    char *net;
#endif
#ifndef RFC1535
    int dots;
#endif

    /*
     * These three fields used to be statically initialized.  This made
     * it hard to use this code in a shared library.  It is necessary,
     * now that we're doing dynamic initialization here, that we preserve
     * the old semantics: if an application modifies one of these three
     * fields of _res before res_init() is called, res_init() will not
     * alter them.  Of course, if an application is setting them to
     * _zero_ before calling res_init(), hoping to override what used
     * to be the static default, we can't detect it and unexpected results
     * will follow.  Zero for any of these fields would make no sense,
     * so one can safely assume that the applications were already getting
     * unexpected results.
     *
     * _res.options is tricky since some apps were known to diddle the bits
     * before res_init() was first called. We can't replicate that semantic
     * with dynamic initialization (they may have turned bits off that are
     * set in RES_DEFAULT).  Our solution is to declare such applications
     * "broken".  They could fool us by setting RES_INIT but none do (yet).
     */
    if (!_res.retrans)
        _res.retrans = RES_TIMEOUT;
    if (!_res.retry)
        _res.retry = 4;
    if (!(_res.options & RES_INIT))
        _res.options = RES_DEFAULT;

    /*
     * This one used to initialize implicitly to zero, so unless the app
     * has set it to something in particular, we can randomize it now.
     */
    if (!_res.id)
        _res.id = (u_short)res_randomid();

#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.ndots = 1;
    _res.pfcode = 0;

    /* Allow user to override the local domain definition */
#ifdef _ORG_FREEBSD_
    if (issetugid() == 0 && (cp = getenv("LOCALDOMAIN")) != NULL)
#else
    if ((cp = getenv("LOCALDOMAIN")) != NULL)
#endif
    {
        (void)strncpy(_res.defdname, cp, sizeof(_res.defdname) - 1);
        _res.defdname[sizeof(_res.defdname) - 1] = '\0';
        haveenv++;

        /*
         * Set search list to be blank-separated strings
         * from rest of env value.  Permits users of LOCALDOMAIN
         * to still have a search list, and anyone to set the
         * one that they want to use as an individual (even more
         * important now that the rfc1535 stuff restricts searches)
         */
        cp = _res.defdname;
        pp = _res.dnsrch;
        *pp++ = cp;
        for (n = 0; *cp && pp < _res.dnsrch + MAXDNSRCH; cp++) {
            if (*cp == '\n')    /* silly backwards compat */
                break;
            else if (*cp == ' ' || *cp == '\t') {
                *cp = 0;
                n = 1;
            } else if (n) {
                *pp++ = cp;
                n = 0;
                havesearch = 1;
            }
        }
        /* null terminate last domain if there are excess */
        while (*cp != '\0' && *cp != ' ' && *cp != '\t' && *cp != '\n')
            cp++;
        *cp = '\0';
        *pp++ = 0;
    }

#define MATCH(line, name) \
    (!strncmp(line, name, sizeof(name) - 1) && \
    (line[sizeof(name) - 1] == ' ' || \
     line[sizeof(name) - 1] == '\t'))

    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 (MATCH(buf, "domain")) {
            if (haveenv)    /* skip if have from environ */
                continue;
            cp = buf + sizeof("domain") - 1;
            while (*cp == ' ' || *cp == '\t')
                cp++;
            if ((*cp == '\0') || (*cp == '\n'))
                continue;
            strncpy(_res.defdname, cp, sizeof(_res.defdname) - 1);
            _res.defdname[sizeof(_res.defdname) - 1] = '\0';
            if ((cp = strpbrk(_res.defdname, " \t\n")) != NULL)
                *cp = '\0';
            havesearch = 0;
            continue;
        }
        /* set search list */
        if (MATCH(buf, "search")) {
            if (haveenv)    /* skip if have from environ */
                continue;
            cp = buf + sizeof("search") - 1;
            while (*cp == ' ' || *cp == '\t')
                cp++;
            if ((*cp == '\0') || (*cp == '\n'))
                continue;
            strncpy(_res.defdname, cp, sizeof(_res.defdname) - 1);
            _res.defdname[sizeof(_res.defdname) - 1] = '\0';
            if ((cp = strchr(_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 (MATCH(buf, "nameserver") && 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;
        }
#ifdef RESOLVSORT
        if (MATCH(buf, "sortlist")) {
            struct in_addr a;

            cp = buf + sizeof("sortlist") - 1;
            while (nsort < MAXRESOLVSORT) {
            while (*cp == ' ' || *cp == '\t')
                cp++;
            if (*cp == '\0' || *cp == '\n' || *cp == ';')
                break;
            net = cp;
            while (*cp && !ISSORTMASK(*cp) && *cp != ';' &&
                   isascii(*cp) && !isspace(*cp))
                cp++;
            n = *cp;
            *cp = 0;
            if (inet_aton(net, &a)) {
                _res.sort_list[nsort].addr = a;
                if (ISSORTMASK(n)) {
                *cp++ = (char)n;
                net = cp;
                while (*cp && *cp != ';' &&
                    isascii(*cp) && !isspace(*cp))
                    cp++;
                n = *cp;
                *cp = 0;
                if (inet_aton(net, &a)) {
                    _res.sort_list[nsort].mask = a.s_addr;
                } else {
                    _res.sort_list[nsort].mask =
                    net_mask(_res.sort_list[nsort].addr);
                }
                } else {
                _res.sort_list[nsort].mask =
                    net_mask(_res.sort_list[nsort].addr);
                }
                nsort++;
            }
            *cp = (char)n;
            }
            continue;
        }
#endif
        if (MATCH(buf, "options")) {
            res_setoptions(buf + sizeof("options") - 1, "conf");
            continue;
        }
        }
        if (nserv > 1)
        _res.nscount = nserv;
#ifdef RESOLVSORT
        _res.nsort = nsort;
#endif
        (void) fclose(fp);
    }
    if (_res.defdname[0] == 0 &&
        gethostname(buf, sizeof(_res.defdname) - 1) == 0 &&
        (cp = strchr(buf, '.')) != NULL)
        strcpy(_res.defdname, cp + 1);

    /* find components of local domain that might be searched */
    if (havesearch == 0) {
        pp = _res.dnsrch;
        *pp++ = _res.defdname;
        *pp = NULL;

#ifndef RFC1535
        dots = 0;
        for (cp = _res.defdname; *cp; cp++)
            dots += (*cp == '.');

        cp = _res.defdname;
        while (pp < _res.dnsrch + MAXDFLSRCH) {
            if (dots < LOCALDOMAINPARTS)
                break;
            cp = strchr(cp, '.') + 1;    /* we know there is one */
            *pp++ = cp;
            dots--;
        }
        *pp = NULL;
#ifdef DEBUG
        if (_res.options & RES_DEBUG) {
            printf(";; res_init()... default dnsrch list:\n");
            for (pp = _res.dnsrch; *pp; pp++)
                printf(";;\t%s\n", *pp);
            printf(";;\t..END..\n");
        }
#endif
#endif /* !RFC1535 */
    }

#ifdef _ORG_FREEBSD_
    if (issetugid())
#else
    if (1)
#endif
        _res.options |= RES_NOALIASES;
    else if ((cp = getenv("RES_OPTIONS")) != NULL)
        res_setoptions(cp, "env");
    _res.options |= RES_INIT;
    if ( 0 == nserv ) {
      return -1;
    }
    return (0);
}

static void
res_setoptions(
    char *options,
    char *source
    )
{
    char *cp = options;
    int i;

#ifdef DEBUG
    if (_res.options & RES_DEBUG)
        printf(";; res_setoptions(\"%s\", \"%s\")...\n",
               options, source);
#endif
    while (*cp) {
        /* skip leading and inner runs of spaces */
        while (*cp == ' ' || *cp == '\t')
            cp++;
        /* search for and process individual options */
        if (!strncmp(cp, "ndots:", sizeof("ndots:") - 1)) {
            i = atoi(cp + sizeof("ndots:") - 1);
            if (i <= RES_MAXNDOTS)
                _res.ndots = i;
            else
                _res.ndots = RES_MAXNDOTS;
#ifdef DEBUG
            if (_res.options & RES_DEBUG)
                printf(";;\tndots=%d\n", _res.ndots);
#endif
        } else if (!strncmp(cp, "debug", sizeof("debug") - 1)) {
#ifdef DEBUG
            if (!(_res.options & RES_DEBUG)) {
                printf(";; res_setoptions(\"%s\", \"%s\")..\n",
                       options, source);
                _res.options |= RES_DEBUG;
            }
            printf(";;\tdebug\n");
#endif
        } else if (!strncmp(cp, "inet6", sizeof("inet6") - 1)) {
            _res.options |= RES_USE_INET6;
        } else if (!strncmp(cp, "no_tld_query", sizeof("no_tld_query") - 1)) {
            _res.options |= RES_NOTLDQUERY;
        } else {
            /* XXX - print a warning here? */
        }
        /* skip to next run of spaces */
        while (*cp && *cp != ' ' && *cp != '\t')
            cp++;
    }
}

#ifdef RESOLVSORT
/* XXX - should really support CIDR which means explicit masks always. */
static u_int32_t
net_mask(
    struct in_addr in
    )
{
    register u_int32_t i = ntohl(in.s_addr);

    if (IN_CLASSA(i))
        return (htonl(IN_CLASSA_NET));
    else if (IN_CLASSB(i))
        return (htonl(IN_CLASSB_NET));
    return (htonl(IN_CLASSC_NET));
}
#endif

u_int
res_randomid()
{
    struct timeval now;

    gettimeofday(&now, NULL);
    return (0xffff & (now.tv_sec ^ now.tv_usec /* ^ getpid() */));
}