InfoMagic Source Code 1993 July/THE_SOURCE_CODE_CD_ROM.iso/bsd_srcs/usr.sbin/named/db_lookup.c

C/C++ Source or Header | 1991-04-24 | 4.6 KB | 173 lines

/*
 * Copyright (c) 1986 Regents of the University of California.
 * 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 and its contributors.
 * 4. Neither the name of the University nor the names of its 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 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 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.
 */

#ifndef lint
static char sccsid[] = "@(#)db_lookup.c    4.18 (Berkeley) 3/21/91";
#endif /* not lint */

/*
 * Table lookup routines.
 */

#include <sys/param.h>
#include <arpa/nameser.h>
#include <stdio.h>
#include "db.h"

struct hashbuf *hashtab;    /* root hash table */
struct hashbuf *fcachetab;    /* hash table of cache read from file */

#ifdef DEBUG
extern int debug;
extern FILE *ddt;
#endif

/*
 * Lookup 'name' and return a pointer to the namebuf;
 * NULL otherwise. If 'insert', insert name into tables.
 * Wildcard lookups are handled.
 */
struct namebuf *
nlookup(name, htpp, fname, insert)
    char *name;
    struct hashbuf **htpp;
    char **fname;
    int insert;
{
    register struct namebuf *np;
    register char *cp;
    register int c;
    register unsigned hval;
    register struct hashbuf *htp;
    struct namebuf *parent = NULL;

    htp = *htpp;
    hval = 0;
    *fname = "???";
    for (cp = name; c = *cp++; ) {
        if (c == '.') {
            parent = np = nlookup(cp, htpp, fname, insert);
            if (np == NULL)
                return (NULL);
            if (*fname != cp)
                return (np);
            if ((htp = np->n_hash) == NULL) {
                if (!insert) {
                    if (np->n_dname[0] == '*' &&
                        np->n_dname[1] == '\0')
                        *fname = name;
                    return (np);
                }
                htp = savehash((struct hashbuf *)NULL);
                np->n_hash = htp;
            }
            *htpp = htp;
            break;
        }
        hval <<= HASHSHIFT;
        hval += c & HASHMASK;
    }
    c = *--cp;
    *cp = '\0';
    /*
     * Lookup this label in current hash table.
     */
    for (np = htp->h_tab[hval % htp->h_size]; np != NULL; np = np->n_next) {
        if (np->n_hashval == hval &&
            strcasecmp(name, np->n_dname) == 0) {
            *cp = c;
            *fname = name;
            return (np);
        }
    }
    if (!insert) {
        /*
         * Look for wildcard in this hash table.
         * Don't use a cached "*" name as a wildcard,
         * only authoritative.
         */
        hval = ('*' & HASHMASK)  % htp->h_size;
        for (np = htp->h_tab[hval]; np != NULL; np = np->n_next) {
            if (np->n_dname[0] == '*'  && np->n_dname[1] == '\0' &&
                np->n_data && np->n_data->d_zone != 0) {
                *cp = c;
                *fname = name;
                return (np);
            }
        }
        *cp = c;
        return (parent);
    }
    np = savename(name);
    np->n_parent = parent;
    np->n_hashval = hval;
    hval %= htp->h_size;
    np->n_next = htp->h_tab[hval];
    htp->h_tab[hval] = np;
    /* increase hash table size */
    if (++htp->h_cnt > htp->h_size * 2) {
        *htpp = savehash(htp);
        if (parent == NULL) {
            if (htp == hashtab)
                hashtab = *htpp;
            else
                fcachetab = *htpp;
        }
        else
            parent->n_hash = *htpp;
        htp = *htpp;
    }
    *cp = c;
    *fname = name;
    return (np);
}

/*
 * Does the data record match the class and type?
 */
match(dp, class, type)
    register struct databuf *dp;
    register int class, type;
{
#ifdef DEBUG
    if (debug >= 5)
        fprintf(ddt,"match(0x%x, %d, %d) %d, %d\n", dp, class, type,
            dp->d_class, dp->d_type);
#endif
    if (dp->d_class != class && class != C_ANY)
        return (0);
    if (dp->d_type != type && type != T_ANY)
        return (0);
    return (1);
}