120 lines
3.5 KiB
C
120 lines
3.5 KiB
C
/* $OpenBSD: hash.c,v 1.9 2004/05/10 15:30:47 deraadt Exp $ */
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/* Routines for manipulating hash tables... */
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/*
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* Copyright (c) 1995, 1996, 1997, 1998 The Internet Software Consortium.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of The Internet Software Consortium nor the names
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* of its contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
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* CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* This software has been written for the Internet Software Consortium
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* by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
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* Enterprises. To learn more about the Internet Software Consortium,
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* see ``http://www.vix.com/isc''. To learn more about Vixie
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* Enterprises, see ``http://www.vix.com''.
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*/
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#include "dhcpd.h"
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static int do_hash(unsigned char *, int, int);
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struct hash_table *
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new_hash(void)
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{
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struct hash_table *rv = new_hash_table(DEFAULT_HASH_SIZE);
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if (!rv)
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return (rv);
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memset(&rv->buckets[0], 0,
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DEFAULT_HASH_SIZE * sizeof(struct hash_bucket *));
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return (rv);
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}
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static int
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do_hash(unsigned char *name, int len, int size)
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{
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unsigned char *s = name;
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int accum = 0, i = len;
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while (i--) {
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/* Add the character in... */
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accum += *s++;
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/* Add carry back in... */
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while (accum > 255)
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accum = (accum & 255) + (accum >> 8);
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}
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return (accum % size);
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}
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void add_hash(struct hash_table *table, unsigned char *name, int len,
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unsigned char *pointer)
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{
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struct hash_bucket *bp;
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int hashno;
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if (!table)
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return;
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if (!len)
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len = strlen((char *)name);
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hashno = do_hash(name, len, table->hash_count);
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bp = new_hash_bucket();
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if (!bp) {
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warning("Can't add %s to hash table.", name);
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return;
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}
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bp->name = name;
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bp->value = pointer;
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bp->next = table->buckets[hashno];
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bp->len = len;
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table->buckets[hashno] = bp;
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}
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unsigned char *
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hash_lookup(struct hash_table *table, unsigned char *name, int len)
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{
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struct hash_bucket *bp;
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int hashno;
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if (!table)
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return (NULL);
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if (!len)
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len = strlen((char *)name);
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hashno = do_hash(name, len, table->hash_count);
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for (bp = table->buckets[hashno]; bp; bp = bp->next)
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if (len == bp->len && !memcmp(bp->name, name, len))
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return (bp->value);
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return (NULL);
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}
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