2 * Copyright (C) 2004-2006 Internet Systems Consortium, Inc. ("ISC")
3 * Copyright (C) 2003 Internet Software Consortium.
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
9 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
10 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
11 * AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
12 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
13 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
14 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
15 * PERFORMANCE OF THIS SOFTWARE.
18 /* $Id: hash.c,v 1.6.18.5 2006/01/04 00:37:23 marka Exp $ */
21 * Some portion of this code was derived from universal hash function
22 * libraries of Rice University.
23 \section license UH Universal Hashing Library
25 Copyright ((c)) 2002, Rice University
28 Redistribution and use in source and binary forms, with or without
29 modification, are permitted provided that the following conditions are
32 * Redistributions of source code must retain the above copyright
33 notice, this list of conditions and the following disclaimer.
35 * Redistributions in binary form must reproduce the above
36 copyright notice, this list of conditions and the following
37 disclaimer in the documentation and/or other materials provided
38 with the distribution.
40 * Neither the name of Rice University (RICE) nor the names of its
41 contributors may be used to endorse or promote products derived
42 from this software without specific prior written permission.
45 This software is provided by RICE and the contributors on an "as is"
46 basis, without any representations or warranties of any kind, express
47 or implied including, but not limited to, representations or
48 warranties of non-infringement, merchantability or fitness for a
49 particular purpose. In no event shall RICE or contributors be liable
50 for any direct, indirect, incidental, special, exemplary, or
51 consequential damages (including, but not limited to, procurement of
52 substitute goods or services; loss of use, data, or profits; or
53 business interruption) however caused and on any theory of liability,
54 whether in contract, strict liability, or tort (including negligence
55 or otherwise) arising in any way out of the use of this software, even
56 if advised of the possibility of such damage.
61 #include <isc/entropy.h>
64 #include <isc/magic.h>
65 #include <isc/mutex.h>
67 #include <isc/random.h>
68 #include <isc/refcount.h>
69 #include <isc/string.h>
72 #define HASH_MAGIC ISC_MAGIC('H', 'a', 's', 'h')
73 #define VALID_HASH(h) ISC_MAGIC_VALID((h), HASH_MAGIC)
76 * A large 32-bit prime number that specifies the range of the hash output.
78 #define PRIME32 0xFFFFFFFB /* 2^32 - 5 */
82 * Types of random seed and hash accumulator. Perhaps they can be system
85 typedef isc_uint32_t hash_accum_t;
86 typedef isc_uint16_t hash_random_t;
89 /*% isc hash structure */
94 isc_boolean_t initialized;
95 isc_refcount_t refcnt;
96 isc_entropy_t *entropy; /*%< entropy source */
97 unsigned int limit; /*%< upper limit of key length */
98 size_t vectorlen; /*%< size of the vector below */
99 hash_random_t *rndvector; /*%< random vector for universal hashing */
102 static isc_mutex_t createlock;
103 static isc_once_t once = ISC_ONCE_INIT;
104 static isc_hash_t *hash = NULL;
106 static unsigned char maptolower[] = {
107 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
108 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
109 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
110 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
111 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
112 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
113 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
114 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
115 0x40, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67,
116 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f,
117 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77,
118 0x78, 0x79, 0x7a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f,
119 0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67,
120 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f,
121 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77,
122 0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f,
123 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
124 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
125 0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97,
126 0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f,
127 0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
128 0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf,
129 0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7,
130 0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf,
131 0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,
132 0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf,
133 0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7,
134 0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf,
135 0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7,
136 0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef,
137 0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
138 0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff
142 isc_hash_ctxcreate(isc_mem_t *mctx, isc_entropy_t *entropy,
143 unsigned int limit, isc_hash_t **hctxp)
149 hash_accum_t overflow_limit;
151 REQUIRE(mctx != NULL);
152 REQUIRE(hctxp != NULL && *hctxp == NULL);
155 * Overflow check. Since our implementation only does a modulo
156 * operation at the last stage of hash calculation, the accumulator
160 1 << (((sizeof(hash_accum_t) - sizeof(hash_random_t))) * 8);
161 if (overflow_limit < (limit + 1) * 0xff)
162 return (ISC_R_RANGE);
164 hctx = isc_mem_get(mctx, sizeof(isc_hash_t));
166 return (ISC_R_NOMEMORY);
168 vlen = sizeof(hash_random_t) * (limit + 1);
169 rv = isc_mem_get(mctx, vlen);
171 result = ISC_R_NOMEMORY;
178 result = isc_mutex_init(&hctx->lock);
179 if (result != ISC_R_SUCCESS)
183 * From here down, no failures will/can occur.
185 hctx->magic = HASH_MAGIC;
187 isc_mem_attach(mctx, &hctx->mctx);
188 hctx->initialized = ISC_FALSE;
189 result = isc_refcount_init(&hctx->refcnt, 1);
190 if (result != ISC_R_SUCCESS)
192 hctx->entropy = NULL;
194 hctx->vectorlen = vlen;
195 hctx->rndvector = rv;
198 isc_entropy_attach(entropy, &hctx->entropy);
201 return (ISC_R_SUCCESS);
204 DESTROYLOCK(&hctx->lock);
206 isc_mem_put(mctx, hctx, sizeof(isc_hash_t));
208 isc_mem_put(mctx, rv, vlen);
214 initialize_lock(void) {
215 RUNTIME_CHECK(isc_mutex_init(&createlock) == ISC_R_SUCCESS);
219 isc_hash_create(isc_mem_t *mctx, isc_entropy_t *entropy, size_t limit) {
220 isc_result_t result = ISC_R_SUCCESS;
222 REQUIRE(mctx != NULL);
223 INSIST(hash == NULL);
225 RUNTIME_CHECK(isc_once_do(&once, initialize_lock) == ISC_R_SUCCESS);
230 result = isc_hash_ctxcreate(mctx, entropy, limit, &hash);
238 isc_hash_ctxinit(isc_hash_t *hctx) {
243 if (hctx->initialized == ISC_TRUE)
247 result = isc_entropy_getdata(hctx->entropy,
248 hctx->rndvector, hctx->vectorlen,
250 INSIST(result == ISC_R_SUCCESS);
253 unsigned int i, copylen;
256 p = (unsigned char *)hctx->rndvector;
257 for (i = 0; i < hctx->vectorlen; i += copylen, p += copylen) {
259 if (i + sizeof(pr) <= hctx->vectorlen)
260 copylen = sizeof(pr);
262 copylen = hctx->vectorlen - i;
264 memcpy(p, &pr, copylen);
266 INSIST(p == (unsigned char *)hctx->rndvector +
270 hctx->initialized = ISC_TRUE;
278 INSIST(hash != NULL && VALID_HASH(hash));
280 isc_hash_ctxinit(hash);
284 isc_hash_ctxattach(isc_hash_t *hctx, isc_hash_t **hctxp) {
285 REQUIRE(VALID_HASH(hctx));
286 REQUIRE(hctxp != NULL && *hctxp == NULL);
288 isc_refcount_increment(&hctx->refcnt, NULL);
293 destroy(isc_hash_t **hctxp) {
297 REQUIRE(hctxp != NULL && *hctxp != NULL);
303 isc_refcount_destroy(&hctx->refcnt);
306 if (hctx->entropy != NULL)
307 isc_entropy_detach(&hctx->entropy);
308 if (hctx->rndvector != NULL)
309 isc_mem_put(mctx, hctx->rndvector, hctx->vectorlen);
313 DESTROYLOCK(&hctx->lock);
315 memset(hctx, 0, sizeof(isc_hash_t));
316 isc_mem_put(mctx, hctx, sizeof(isc_hash_t));
317 isc_mem_detach(&mctx);
321 isc_hash_ctxdetach(isc_hash_t **hctxp) {
325 REQUIRE(hctxp != NULL && VALID_HASH(*hctxp));
328 isc_refcount_decrement(&hctx->refcnt, &refs);
339 INSIST(hash != NULL && VALID_HASH(hash));
341 isc_refcount_decrement(&hash->refcnt, &refs);
347 static inline unsigned int
348 hash_calc(isc_hash_t *hctx, const unsigned char *key, unsigned int keylen,
349 isc_boolean_t case_sensitive)
351 hash_accum_t partial_sum = 0;
352 hash_random_t *p = hctx->rndvector;
355 /* Make it sure that the hash context is initialized. */
356 if (hctx->initialized == ISC_FALSE)
357 isc_hash_ctxinit(hctx);
359 if (case_sensitive) {
360 for (i = 0; i < keylen; i++)
361 partial_sum += key[i] * (hash_accum_t)p[i];
363 for (i = 0; i < keylen; i++)
364 partial_sum += maptolower[key[i]] * (hash_accum_t)p[i];
369 return ((unsigned int)(partial_sum % PRIME32));
373 isc_hash_ctxcalc(isc_hash_t *hctx, const unsigned char *key,
374 unsigned int keylen, isc_boolean_t case_sensitive)
376 REQUIRE(hctx != NULL && VALID_HASH(hctx));
377 REQUIRE(keylen <= hctx->limit);
379 return (hash_calc(hctx, key, keylen, case_sensitive));
383 isc_hash_calc(const unsigned char *key, unsigned int keylen,
384 isc_boolean_t case_sensitive)
386 INSIST(hash != NULL && VALID_HASH(hash));
387 REQUIRE(keylen <= hash->limit);
389 return (hash_calc(hash, key, keylen, case_sensitive));