/*
 * Copyright (c) 1988, 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.
 *
 */

/*
 * 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_query.c 8.1 (Berkeley) 6/4/93";
static char orig_rcsid = "From: Id: res_query.c,v 8.14 1997/06/09 17:47:05 halley Exp $";
static char rcsid[] = "$Id: res_query.c,v 1.1.1.1 2003/11/19 01:51:38 kyu3 Exp $";
#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>
#include <sys/param.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>
#include <ctype.h>
#include <errno.h>
#include <netdb.h>
#include <resolv.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "res_config.h"

#if PACKETSZ > 1024
#define MAXPACKET   PACKETSZ
#else
#define MAXPACKET   1024
#endif

/*
 * Formulate a normal query, send, and await answer.
 * Returned answer is placed in supplied buffer "answer".
 * Perform preliminary check of answer, returning success only
 * if no error is indicated and the answer count is nonzero.
 * Return the size of the response on success, -1 on error.
 * Error number is left in h_errno.
 *
 * Caller must parse answer and determine whether it answers the question.
 */
int
res_query(
    const char *name,   /* domain name */
    int class,          /* class of query */
    int type,           /* type of query */
    u_char *answer,     /* buffer to put answer */
    int anslen          /* size of answer buffer */
    )
{
    u_char buf[MAXPACKET];
    HEADER *hp = (HEADER *) answer;
    int n;

    hp->rcode = NOERROR;    /* default */

    if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
        h_errno = NETDB_INTERNAL;
        return (-1);
    }
#ifdef DEBUG
    if (_res.options & RES_DEBUG)
        printf(";; res_query(%s, %d, %d)\n", name, class, type);
#endif

    n = res_mkquery(QUERY, name, class, type, NULL, 0, NULL,
            buf, sizeof(buf));
    if (n <= 0) {
#ifdef DEBUG
        if (_res.options & RES_DEBUG)
            printf(";; res_query: mkquery failed\n");
#endif
        h_errno = NO_RECOVERY;
        return (n);
    }
    n = res_send(buf, n, answer, anslen);
    if (n < 0) {
#ifdef DEBUG
        if (_res.options & RES_DEBUG)
            printf(";; res_query: send error\n");
#endif
        h_errno = TRY_AGAIN;
        return (n);
    }

    if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
#ifdef DEBUG
        if (_res.options & RES_DEBUG)
            printf(";; rcode = %d, ancount=%d\n", hp->rcode,
                ntohs(hp->ancount));
#endif
        switch (hp->rcode) {
        case NXDOMAIN:
            h_errno = HOST_NOT_FOUND;
            break;
        case SERVFAIL:
            h_errno = TRY_AGAIN;
            break;
        case NOERROR:
            h_errno = NO_DATA;
            break;
        case FORMERR:
        case NOTIMP:
        case REFUSED:
        default:
            h_errno = NO_RECOVERY;
            break;
        }
        return (-1);
    }
    return (n);
}

/*
 * Formulate a normal query, send, and retrieve answer in supplied buffer.
 * Return the size of the response on success, -1 on error.
 * If enabled, implement search rules until answer or unrecoverable failure
 * is detected.  Error code, if any, is left in h_errno.
 */
int
res_search(
    const char *name,   /* domain name */
    int class,          /* class of query */
    int type,           /* type of query */
    u_char *answer,     /* buffer to put answer */
    int anslen          /* size of answer */
    )
{
    const char *cp, * const *domain;
    HEADER *hp = (HEADER *) answer;
    u_int dots;
    int trailing_dot, ret, saved_herrno;
    int got_nodata = 0, got_servfail = 0, tried_as_is = 0;

    if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
        h_errno = NETDB_INTERNAL;
        return (-1);
    }
    errno = 0;
    h_errno = HOST_NOT_FOUND;   /* default, if we never query */
    dots = 0;
    for (cp = name; *cp; cp++)
        dots += (*cp == '.');
    trailing_dot = 0;
    if (cp > name && *--cp == '.')
        trailing_dot++;

    /* If there aren't any dots, it could be a user-level alias */
    if (!dots && (cp = hostalias(name)) != NULL)
        return (res_query(cp, class, type, answer, anslen));

    /*
     * If there are dots in the name already, let's just give it a try
     * 'as is'.  The threshold can be set with the "ndots" option.
     */
    saved_herrno = -1;
    if (dots >= _res.ndots) {
        ret = res_querydomain(name, NULL, class, type, answer, anslen);
        if (ret > 0)
            return (ret);
        saved_herrno = h_errno;
        tried_as_is++;
    }

    /*
     * We do at least one level of search if
     *  - there is no dot and RES_DEFNAME is set, or
     *  - there is at least one dot, there is no trailing dot,
     *    and RES_DNSRCH is set.
     */
    if ((!dots && (_res.options & RES_DEFNAMES)) ||
        (dots && !trailing_dot && (_res.options & RES_DNSRCH))) {
        int done = 0;

        for (domain = (const char * const *)_res.dnsrch;
             *domain && !done;
             domain++) {

            ret = res_querydomain(name, *domain, class, type,
                          answer, anslen);
            if (ret > 0)
                return (ret);

            /*
             * If no server present, give up.
             * If name isn't found in this domain,
             * keep trying higher domains in the search list
             * (if that's enabled).
             * On a NO_DATA error, keep trying, otherwise
             * a wildcard entry of another type could keep us
             * from finding this entry higher in the domain.
             * If we get some other error (negative answer or
             * server failure), then stop searching up,
             * but try the input name below in case it's
             * fully-qualified.
             */
            if (errno == ECONNREFUSED) {
                h_errno = TRY_AGAIN;
                return (-1);
            }

            switch (h_errno) {
            case NO_DATA:
                got_nodata++;
                /* FALLTHROUGH */
            case HOST_NOT_FOUND:
                /* keep trying */
                break;
            case TRY_AGAIN:
                if (hp->rcode == SERVFAIL) {
                    /* try next search element, if any */
                    got_servfail++;
                    break;
                }
                /* FALLTHROUGH */
            default:
                /* anything else implies that we're done */
                done++;
            }

            /* if we got here for some reason other than DNSRCH,
             * we only wanted one iteration of the loop, so stop.
             */
            if (!(_res.options & RES_DNSRCH))
                done++;
        }
    }

    /*
     * If we have not already tried the name "as is", do that now.
     * note that we do this regardless of how many dots were in the
     * name or whether it ends with a dot unless NOTLDQUERY is set.
     */
    if (!tried_as_is && (dots || !(_res.options & RES_NOTLDQUERY))) {
        ret = res_querydomain(name, NULL, class, type, answer, anslen);
        if (ret > 0)
            return (ret);
    }

    /* if we got here, we didn't satisfy the search.
     * if we did an initial full query, return that query's h_errno
     * (note that we wouldn't be here if that query had succeeded).
     * else if we ever got a nodata, send that back as the reason.
     * else send back meaningless h_errno, that being the one from
     * the last DNSRCH we did.
     */
    if (saved_herrno != -1)
        h_errno = saved_herrno;
    else if (got_nodata)
        h_errno = NO_DATA;
    else if (got_servfail)
        h_errno = TRY_AGAIN;
    return (-1);
}

/*
 * Perform a call on res_query on the concatenation of name and domain,
 * removing a trailing dot from name if domain is NULL.
 */
int
res_querydomain(
    const char *name,
    const char *domain,
    int class,      /* class of query */
    int type,       /* type of query */
    u_char *answer, /* buffer to put answer */
    int anslen      /* size of answer */
    )
{
    char nbuf[MAXDNAME];
    const char *longname = nbuf;
    int n, d;

    if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
        h_errno = NETDB_INTERNAL;
        return (-1);
    }
#ifdef DEBUG
    if (_res.options & RES_DEBUG)
        printf(";; res_querydomain(%s, %s, %d, %d)\n",
               name, domain?domain:"<Nil>", class, type);
#endif
    if (domain == NULL) {
        /*
         * Check for trailing '.';
         * copy without '.' if present.
         */
        n = (int)strlen(name);
        if (n >= MAXDNAME) {
            h_errno = NO_RECOVERY;
            return (-1);
        }
        n--;
        if (n >= 0 && name[n] == '.') {
            strncpy(nbuf, name, n);
            nbuf[n] = '\0';
        } else
            longname = name;
    } else {
        n = (int)strlen(name);
        d = (int)strlen(domain);
        if (n + d + 1 >= MAXDNAME) {
            h_errno = NO_RECOVERY;
            return (-1);
        }
        sprintf(nbuf, "%s.%s", name, domain);
    }
    return (res_query(longname, class, type, answer, anslen));
}

const char *
hostalias(
    const char *name
    )
{
    register char *cp1, *cp2;
    FILE *fp;
    char *file;
    char buf[BUFSIZ];
    static char abuf[MAXDNAME];

    if (_res.options & RES_NOALIASES)
        return (NULL);
#ifdef _ORG_FREEBSD_
    if (issetugid())
        return (NULL);
#endif
    file = getenv("HOSTALIASES");
    if (file == NULL || (fp = fopen(file, "r")) == NULL)
        return (NULL);
    setbuf(fp, NULL);
    buf[sizeof(buf) - 1] = '\0';
    while (fgets(buf, sizeof(buf), fp)) {
        for (cp1 = buf; *cp1 && !isspace(*cp1); ++cp1)
            ;
        if (!*cp1)
            break;
        *cp1 = '\0';
        if (!strcasecmp(buf, name)) {
            while (isspace(*++cp1))
                ;
            if (!*cp1)
                break;
            for (cp2 = cp1 + 1; *cp2 && !isspace(*cp2); ++cp2)
                ;
            abuf[sizeof(abuf) - 1] = *cp2 = '\0';
            strncpy(abuf, cp1, sizeof(abuf) - 1);
            fclose(fp);
            return (abuf);
        }
    }
    fclose(fp);
    return (NULL);
}