2 * Copyright (C) 2004 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 1.2.2.5 2004/03/09 06:11:46 marka Exp $ */
21 * Some portion of this code was derived from universal hash function
22 * libraries of Rice University.
25 /* "UH Universal Hashing Library"
27 Copyright ((c)) 2002, Rice University
30 Redistribution and use in source and binary forms, with or without
31 modification, are permitted provided that the following conditions are
34 * Redistributions of source code must retain the above copyright
35 notice, this list of conditions and the following disclaimer.
37 * Redistributions in binary form must reproduce the above
38 copyright notice, this list of conditions and the following
39 disclaimer in the documentation and/or other materials provided
40 with the distribution.
42 * Neither the name of Rice University (RICE) nor the names of its
43 contributors may be used to endorse or promote products derived
44 from this software without specific prior written permission.
47 This software is provided by RICE and the contributors on an "as is"
48 basis, without any representations or warranties of any kind, express
49 or implied including, but not limited to, representations or
50 warranties of non-infringement, merchantability or fitness for a
51 particular purpose. In no event shall RICE or contributors be liable
52 for any direct, indirect, incidental, special, exemplary, or
53 consequential damages (including, but not limited to, procurement of
54 substitute goods or services; loss of use, data, or profits; or
55 business interruption) however caused and on any theory of liability,
56 whether in contract, strict liability, or tort (including negligence
57 or otherwise) arising in any way out of the use of this software, even
58 if advised of the possibility of such damage.
63 #include <isc/entropy.h>
66 #include <isc/magic.h>
67 #include <isc/mutex.h>
69 #include <isc/random.h>
70 #include <isc/refcount.h>
71 #include <isc/rwlock.h>
72 #include <isc/string.h>
75 #define HASH_MAGIC ISC_MAGIC('H', 'a', 's', 'h')
76 #define VALID_HASH(h) ISC_MAGIC_VALID((h), HASH_MAGIC)
79 * A large 32-bit prime number that specifies the range of the hash output.
81 #define PRIME32 0xFFFFFFFB /* 2^32 - 5 */
84 * Types of random seed and hash accumulator. Perhaps they can be system
87 typedef isc_uint32_t hash_accum_t;
88 typedef isc_uint16_t hash_random_t;
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_rwlock_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 ret = ISC_R_NOMEMORY;
178 if (isc_mutex_init(&hctx->lock) != ISC_R_SUCCESS) {
179 ret = ISC_R_UNEXPECTED;
184 * From here down, no failures will/can occur.
186 hctx->magic = HASH_MAGIC;
188 isc_mem_attach(mctx, &hctx->mctx);
189 hctx->initialized = ISC_FALSE;
190 isc_refcount_init(&hctx->refcnt, 1);
191 hctx->entropy = NULL;
193 hctx->vectorlen = vlen;
194 hctx->rndvector = rv;
197 isc_entropy_attach(entropy, &hctx->entropy);
200 return (ISC_R_SUCCESS);
203 isc_mem_put(mctx, hctx, sizeof(isc_hash_t));
205 isc_mem_put(mctx, rv, vlen);
211 initialize_lock(void) {
212 RUNTIME_CHECK(isc_rwlock_init(&createlock, 0, 0) == ISC_R_SUCCESS);
216 isc_hash_create(isc_mem_t *mctx, isc_entropy_t *entropy, size_t limit) {
217 isc_result_t result = ISC_R_SUCCESS;
219 REQUIRE(mctx != NULL);
220 INSIST(hash == NULL);
222 RUNTIME_CHECK(isc_once_do(&once, initialize_lock) == ISC_R_SUCCESS);
224 RWLOCK(&createlock, isc_rwlocktype_write);
227 result = isc_hash_ctxcreate(mctx, entropy, limit, &hash);
229 RWUNLOCK(&createlock, isc_rwlocktype_write);
235 isc_hash_ctxinit(isc_hash_t *hctx) {
240 if (hctx->initialized == ISC_TRUE)
244 result = isc_entropy_getdata(hctx->entropy,
245 hctx->rndvector, hctx->vectorlen,
247 INSIST(result == ISC_R_SUCCESS);
250 unsigned int i, copylen;
253 p = (unsigned char *)hctx->rndvector;
254 for (i = 0; i < hctx->vectorlen; i += copylen, p += copylen) {
256 if (i + sizeof(pr) <= hctx->vectorlen)
257 copylen = sizeof(pr);
259 copylen = hctx->vectorlen - i;
261 memcpy(p, &pr, copylen);
263 INSIST(p == (unsigned char *)hctx->rndvector +
267 hctx->initialized = ISC_TRUE;
275 INSIST(hash != NULL && VALID_HASH(hash));
277 isc_hash_ctxinit(hash);
281 isc_hash_ctxattach(isc_hash_t *hctx, isc_hash_t **hctxp) {
282 REQUIRE(VALID_HASH(hctx));
283 REQUIRE(hctxp != NULL && *hctxp == NULL);
285 isc_refcount_increment(&hctx->refcnt, NULL);
290 destroy(isc_hash_t **hctxp) {
294 REQUIRE(hctxp != NULL && *hctxp != NULL);
300 isc_refcount_destroy(&hctx->refcnt);
303 if (hctx->entropy != NULL)
304 isc_entropy_detach(&hctx->entropy);
305 if (hctx->rndvector != NULL)
306 isc_mem_put(mctx, hctx->rndvector, hctx->vectorlen);
310 DESTROYLOCK(&hctx->lock);
312 memset(hctx, 0, sizeof(isc_hash_t));
313 isc_mem_put(mctx, hctx, sizeof(isc_hash_t));
314 isc_mem_detach(&mctx);
318 isc_hash_ctxdetach(isc_hash_t **hctxp) {
322 REQUIRE(hctxp != NULL && VALID_HASH(*hctxp));
325 isc_refcount_decrement(&hctx->refcnt, &refs);
336 INSIST(hash != NULL && VALID_HASH(hash));
338 isc_refcount_decrement(&hash->refcnt, &refs);
344 static inline unsigned int
345 hash_calc(isc_hash_t *hctx, const unsigned char *key, unsigned int keylen,
346 isc_boolean_t case_sensitive)
348 hash_accum_t partial_sum = 0;
349 hash_random_t *p = hctx->rndvector;
352 /* Make it sure that the hash context is initialized. */
353 if (hctx->initialized == ISC_FALSE)
354 isc_hash_ctxinit(hctx);
356 if (case_sensitive) {
357 for (i = 0; i < keylen; i++)
358 partial_sum += key[i] * (hash_accum_t)p[i];
360 for (i = 0; i < keylen; i++)
361 partial_sum += maptolower[key[i]] * (hash_accum_t)p[i];
366 return ((unsigned int)(partial_sum % PRIME32));
370 isc_hash_ctxcalc(isc_hash_t *hctx, const unsigned char *key,
371 unsigned int keylen, isc_boolean_t case_sensitive)
373 REQUIRE(hctx != NULL && VALID_HASH(hctx));
374 REQUIRE(keylen <= hctx->limit);
376 return (hash_calc(hctx, key, keylen, case_sensitive));
380 isc_hash_calc(const unsigned char *key, unsigned int keylen,
381 isc_boolean_t case_sensitive)
383 INSIST(hash != NULL && VALID_HASH(hash));
384 REQUIRE(keylen <= hash->limit);
386 return (hash_calc(hash, key, keylen, case_sensitive));