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/* $OpenBSD: hash.c,v 1.6 2010/01/01 20:30:25 krw Exp $ */
/* Routines for manipulating hash tables... */
/*
* Copyright (c) 1995, 1996, 1997, 1998 The Internet Software Consortium.
* 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. Neither the name of The Internet Software Consortium 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 INTERNET SOFTWARE CONSORTIUM 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 INTERNET SOFTWARE CONSORTIUM 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.
*
* This software has been written for the Internet Software Consortium
* by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
* Enterprises. To learn more about the Internet Software Consortium,
* see ``http://www.vix.com/isc''. To learn more about Vixie
* Enterprises, see ``http://www.vix.com''.
*/
#include "dhcpd.h"
static int do_hash(unsigned char *, int, int);
struct hash_table *
new_hash(void)
{
struct hash_table *rv;
rv = calloc(1, sizeof(struct hash_table));
if (!rv)
warning("No memory for new hash.");
else
rv->hash_count = DEFAULT_HASH_SIZE;
return (rv);
}
static int
do_hash(unsigned char *name, int len, int size)
{
int accum = 0;
unsigned char *s = name;
int i = len;
while (i--) {
/* Add the character in... */
accum += *s++;
/* Add carry back in... */
while (accum > 255)
accum = (accum & 255) + (accum >> 8);
}
return (accum % size);
}
void add_hash(struct hash_table *table, unsigned char *name, int len,
unsigned char *pointer)
{
int hashno;
struct hash_bucket *bp;
if (!table)
return;
if (!len)
len = strlen((char *)name);
hashno = do_hash(name, len, table->hash_count);
bp = calloc(1, sizeof(struct hash_bucket));
if (!bp) {
warning("Can't add %s to hash table.", name);
return;
}
bp->name = name;
bp->value = pointer;
bp->next = table->buckets[hashno];
bp->len = len;
table->buckets[hashno] = bp;
}
void
delete_hash_entry(struct hash_table *table, unsigned char *name, int len)
{
int hashno;
struct hash_bucket *bp, *pbp = NULL;
if (!table)
return;
if (!len)
len = strlen((char *)name);
hashno = do_hash(name, len, table->hash_count);
/*
* Go through the list looking for an entry that matches; if we
* find it, delete it.
*/
for (bp = table->buckets[hashno]; bp; bp = bp->next) {
if ((!bp->len &&
!strcmp((char *)bp->name, (char *)name)) ||
(bp->len == len && !memcmp(bp->name, name, len))) {
if (pbp)
pbp->next = bp->next;
else
table->buckets[hashno] = bp->next;
free(bp);
break;
}
pbp = bp; /* jwg, 9/6/96 - nice catch! */
}
}
unsigned char *
hash_lookup(struct hash_table *table, unsigned char *name, int len)
{
int hashno;
struct hash_bucket *bp;
if (!table)
return (NULL);
if (!len)
len = strlen((char *)name);
hashno = do_hash(name, len, table->hash_count);
for (bp = table->buckets[hashno]; bp; bp = bp->next)
if (len == bp->len && !memcmp(bp->name, name, len))
return (bp->value);
return (NULL);
}
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