1/*	$OpenBSD: hash.c,v 1.9 2004/05/10 15:30:47 deraadt Exp $	*/
2
3/* Routines for manipulating hash tables... */
4
5/*
6 * Copyright (c) 1995, 1996, 1997, 1998 The Internet Software Consortium.
7 * All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 *
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of The Internet Software Consortium nor the names
19 *    of its contributors may be used to endorse or promote products derived
20 *    from this software without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
23 * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
24 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
25 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
26 * DISCLAIMED.  IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
27 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
28 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
29 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
30 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
31 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
32 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
33 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 *
36 * This software has been written for the Internet Software Consortium
37 * by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
38 * Enterprises.  To learn more about the Internet Software Consortium,
39 * see ``http://www.vix.com/isc''.  To learn more about Vixie
40 * Enterprises, see ``http://www.vix.com''.
41 */
42
43#include <sys/cdefs.h>
44__FBSDID("$FreeBSD$");
45
46#include "dhcpd.h"
47
48static int do_hash(unsigned char *, int, int);
49
50struct hash_table *
51new_hash(void)
52{
53	struct hash_table *rv = new_hash_table(DEFAULT_HASH_SIZE);
54
55	if (!rv)
56		return (rv);
57	memset(&rv->buckets[0], 0,
58	    DEFAULT_HASH_SIZE * sizeof(struct hash_bucket *));
59	return (rv);
60}
61
62static int
63do_hash(unsigned char *name, int len, int size)
64{
65	unsigned char *s = name;
66	int accum = 0, i = len;
67
68	while (i--) {
69		/* Add the character in... */
70		accum += *s++;
71		/* Add carry back in... */
72		while (accum > 255)
73			accum = (accum & 255) + (accum >> 8);
74	}
75	return (accum % size);
76}
77
78void add_hash(struct hash_table *table, unsigned char *name, int len,
79    unsigned char *pointer)
80{
81	struct hash_bucket *bp;
82	int hashno;
83
84	if (!table)
85		return;
86	if (!len)
87		len = strlen((char *)name);
88
89	hashno = do_hash(name, len, table->hash_count);
90	bp = new_hash_bucket();
91
92	if (!bp) {
93		warning("Can't add %s to hash table.", name);
94		return;
95	}
96	bp->name = name;
97	bp->value = pointer;
98	bp->next = table->buckets[hashno];
99	bp->len = len;
100	table->buckets[hashno] = bp;
101}
102
103unsigned char *
104hash_lookup(struct hash_table *table, unsigned char *name, int len)
105{
106	struct hash_bucket *bp;
107	int hashno;
108
109	if (!table)
110		return (NULL);
111
112	if (!len)
113		len = strlen((char *)name);
114
115	hashno = do_hash(name, len, table->hash_count);
116
117	for (bp = table->buckets[hashno]; bp; bp = bp->next)
118		if (len == bp->len && !memcmp(bp->name, name, len))
119			return (bp->value);
120
121	return (NULL);
122}
123