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db_lookup.c
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1993-08-24
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/*
* Copyright (c) 1986 Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms are permitted provided
* that: (1) source distributions retain this entire copyright notice and
* comment, and (2) distributions including binaries display the following
* acknowledgement: ``This product includes software developed by the
* University of California, Berkeley and its contributors'' in the
* documentation or other materials provided with the distribution and in
* all advertising materials mentioning features or use of this software.
* 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 ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
#ifndef lint
static char sccsid[] = "@(#)db_lookup.c 4.17 (Berkeley) 6/1/90";
#endif /* not lint */
/*
* Table lookup routines.
*/
#include <sys/types.h>
#include <stdio.h>
#include <arpa/nameser.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);
}