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 * SPDX-License-Identifier: BSD-3-Clause
7 *
8 * Copyright (c) 1995, 1996, 1997, 1998 The Internet Software Consortium.
9 * All rights reserved.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 *
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. Neither the name of The Internet Software Consortium nor the names
21 * of its contributors may be used to endorse or promote products derived
22 * from this software without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
25 * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
26 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
27 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
28 * DISCLAIMED. IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
29 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
30 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
31 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
32 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
33 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
34 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
35 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 *
38 * This software has been written for the Internet Software Consortium
39 * by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
40 * Enterprises. To learn more about the Internet Software Consortium,
41 * see ``http://www.vix.com/isc''. To learn more about Vixie
42 * Enterprises, see ``http://www.vix.com''.
43 */
44
45 #include <sys/cdefs.h>
46 #include "dhcpd.h"
47
48 static int do_hash(const unsigned char *, int, int);
49
50 struct hash_table *
new_hash(void)51 new_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
62 static int
do_hash(const unsigned char * name,int len,int size)63 do_hash(const unsigned char *name, int len, int size)
64 {
65 const 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
add_hash(struct hash_table * table,const unsigned char * name,int len,unsigned char * pointer)78 void add_hash(struct hash_table *table, const 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((const 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
103 void *
hash_lookup(struct hash_table * table,unsigned char * name,int len)104 hash_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