1 /* $NetBSD: hash.c,v 1.9 2015/07/08 17:28:59 christos Exp $ */
2
3 /*
4 * Copyright (C) 2004-2007, 2009, 2013-2015 Internet Systems Consortium, Inc. ("ISC")
5 * Copyright (C) 2003 Internet Software Consortium.
6 *
7 * Permission to use, copy, modify, and/or distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
10 *
11 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
12 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
13 * AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
14 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
15 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
16 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
17 * PERFORMANCE OF THIS SOFTWARE.
18 */
19
20 /* Id: hash.c,v 1.16 2009/09/01 00:22:28 jinmei Exp */
21
22 /*! \file
23 * Some portion of this code was derived from universal hash function
24 * libraries of Rice University.
25 \section license UH Universal Hashing Library
26
27 Copyright ((c)) 2002, Rice University
28 All rights reserved.
29
30 Redistribution and use in source and binary forms, with or without
31 modification, are permitted provided that the following conditions are
32 met:
33
34 * Redistributions of source code must retain the above copyright
35 notice, this list of conditions and the following disclaimer.
36
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.
41
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.
45
46
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.
59 */
60
61 #include <config.h>
62
63 #include <isc/entropy.h>
64 #include <isc/hash.h>
65 #include <isc/mem.h>
66 #include <isc/magic.h>
67 #include <isc/mutex.h>
68 #include <isc/once.h>
69 #include <isc/random.h>
70 #include <isc/refcount.h>
71 #include <isc/string.h>
72 #include <isc/util.h>
73
74 #define HASH_MAGIC ISC_MAGIC('H', 'a', 's', 'h')
75 #define VALID_HASH(h) ISC_MAGIC_VALID((h), HASH_MAGIC)
76
77 /*%
78 * A large 32-bit prime number that specifies the range of the hash output.
79 */
80 #define PRIME32 0xFFFFFFFB /* 2^32 - 5 */
81
82 /*@{*/
83 /*%
84 * Types of random seed and hash accumulator. Perhaps they can be system
85 * dependent.
86 */
87 typedef isc_uint32_t hash_accum_t;
88 typedef isc_uint16_t hash_random_t;
89 /*@}*/
90
91 /*% isc hash structure */
92 struct isc_hash {
93 unsigned int magic;
94 isc_mem_t *mctx;
95 isc_mutex_t lock;
96 isc_boolean_t initialized;
97 isc_refcount_t refcnt;
98 isc_entropy_t *entropy; /*%< entropy source */
99 size_t limit; /*%< upper limit of key length */
100 size_t vectorlen; /*%< size of the vector below */
101 hash_random_t *rndvector; /*%< random vector for universal hashing */
102 };
103
104 static isc_mutex_t createlock;
105 static isc_once_t once = ISC_ONCE_INIT;
106 static isc_hash_t *hash = NULL;
107
108 static unsigned char maptolower[] = {
109 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
110 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
111 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
112 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
113 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
114 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
115 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
116 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
117 0x40, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67,
118 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f,
119 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77,
120 0x78, 0x79, 0x7a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f,
121 0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67,
122 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f,
123 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77,
124 0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f,
125 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
126 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
127 0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97,
128 0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f,
129 0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
130 0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf,
131 0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7,
132 0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf,
133 0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,
134 0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf,
135 0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7,
136 0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf,
137 0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7,
138 0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef,
139 0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
140 0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff
141 };
142
143 isc_result_t
isc_hash_ctxcreate(isc_mem_t * mctx,isc_entropy_t * entropy,size_t limit,isc_hash_t ** hctxp)144 isc_hash_ctxcreate(isc_mem_t *mctx, isc_entropy_t *entropy,
145 size_t limit, isc_hash_t **hctxp)
146 {
147 isc_result_t result;
148 isc_hash_t *hctx;
149 size_t vlen;
150 hash_random_t *rv;
151 hash_accum_t overflow_limit;
152
153 REQUIRE(mctx != NULL);
154 REQUIRE(hctxp != NULL && *hctxp == NULL);
155
156 /*
157 * Overflow check. Since our implementation only does a modulo
158 * operation at the last stage of hash calculation, the accumulator
159 * must not overflow.
160 */
161 overflow_limit =
162 1 << (((sizeof(hash_accum_t) - sizeof(hash_random_t))) * 8);
163 if (overflow_limit < (limit + 1) * 0xff)
164 return (ISC_R_RANGE);
165
166 hctx = isc_mem_get(mctx, sizeof(isc_hash_t));
167 if (hctx == NULL)
168 return (ISC_R_NOMEMORY);
169
170 vlen = sizeof(hash_random_t) * (limit + 1);
171 rv = isc_mem_get(mctx, vlen);
172 if (rv == NULL) {
173 result = ISC_R_NOMEMORY;
174 goto errout;
175 }
176
177 /*
178 * We need a lock.
179 */
180 result = isc_mutex_init(&hctx->lock);
181 if (result != ISC_R_SUCCESS)
182 goto errout;
183
184 /*
185 * From here down, no failures will/can occur.
186 */
187 hctx->magic = HASH_MAGIC;
188 hctx->mctx = NULL;
189 isc_mem_attach(mctx, &hctx->mctx);
190 hctx->initialized = ISC_FALSE;
191 result = isc_refcount_init(&hctx->refcnt, 1);
192 if (result != ISC_R_SUCCESS)
193 goto cleanup_lock;
194 hctx->entropy = NULL;
195 hctx->limit = limit;
196 hctx->vectorlen = vlen;
197 hctx->rndvector = rv;
198
199 if (entropy != NULL)
200 isc_entropy_attach(entropy, &hctx->entropy);
201
202 *hctxp = hctx;
203 return (ISC_R_SUCCESS);
204
205 cleanup_lock:
206 DESTROYLOCK(&hctx->lock);
207 errout:
208 isc_mem_put(mctx, hctx, sizeof(isc_hash_t));
209 if (rv != NULL)
210 isc_mem_put(mctx, rv, vlen);
211
212 return (result);
213 }
214
215 static void
initialize_lock(void)216 initialize_lock(void) {
217 RUNTIME_CHECK(isc_mutex_init(&createlock) == ISC_R_SUCCESS);
218 }
219
220 isc_result_t
isc_hash_create(isc_mem_t * mctx,isc_entropy_t * entropy,size_t limit)221 isc_hash_create(isc_mem_t *mctx, isc_entropy_t *entropy, size_t limit) {
222 isc_result_t result = ISC_R_SUCCESS;
223
224 REQUIRE(mctx != NULL);
225 INSIST(hash == NULL);
226
227 RUNTIME_CHECK(isc_once_do(&once, initialize_lock) == ISC_R_SUCCESS);
228
229 LOCK(&createlock);
230
231 if (hash == NULL)
232 result = isc_hash_ctxcreate(mctx, entropy, limit, &hash);
233
234 UNLOCK(&createlock);
235
236 return (result);
237 }
238
239 void
isc_hash_ctxinit(isc_hash_t * hctx)240 isc_hash_ctxinit(isc_hash_t *hctx) {
241 LOCK(&hctx->lock);
242
243 if (hctx->initialized == ISC_TRUE)
244 goto out;
245
246 if (hctx->entropy != NULL) {
247 isc_result_t result;
248
249 result = isc_entropy_getdata(hctx->entropy,
250 hctx->rndvector,
251 (unsigned int)hctx->vectorlen,
252 NULL, 0);
253 INSIST(result == ISC_R_SUCCESS);
254 } else {
255 isc_uint32_t pr;
256 size_t i, copylen;
257 unsigned char *p;
258
259 p = (unsigned char *)hctx->rndvector;
260 for (i = 0; i < hctx->vectorlen; i += copylen, p += copylen) {
261 isc_random_get(&pr);
262 if (i + sizeof(pr) <= hctx->vectorlen)
263 copylen = sizeof(pr);
264 else
265 copylen = hctx->vectorlen - i;
266
267 memmove(p, &pr, copylen);
268 }
269 INSIST(p == (unsigned char *)hctx->rndvector +
270 hctx->vectorlen);
271 }
272
273 hctx->initialized = ISC_TRUE;
274
275 out:
276 UNLOCK(&hctx->lock);
277 }
278
279 void
isc_hash_init(void)280 isc_hash_init(void) {
281 INSIST(hash != NULL && VALID_HASH(hash));
282
283 isc_hash_ctxinit(hash);
284 }
285
286 void
isc_hash_ctxattach(isc_hash_t * hctx,isc_hash_t ** hctxp)287 isc_hash_ctxattach(isc_hash_t *hctx, isc_hash_t **hctxp) {
288 REQUIRE(VALID_HASH(hctx));
289 REQUIRE(hctxp != NULL && *hctxp == NULL);
290
291 isc_refcount_increment(&hctx->refcnt, NULL);
292 *hctxp = hctx;
293 }
294
295 static void
destroy(isc_hash_t ** hctxp)296 destroy(isc_hash_t **hctxp) {
297 isc_hash_t *hctx;
298 isc_mem_t *mctx;
299
300 REQUIRE(hctxp != NULL && *hctxp != NULL);
301 hctx = *hctxp;
302 *hctxp = NULL;
303
304 LOCK(&hctx->lock);
305
306 isc_refcount_destroy(&hctx->refcnt);
307
308 mctx = hctx->mctx;
309 if (hctx->entropy != NULL)
310 isc_entropy_detach(&hctx->entropy);
311 if (hctx->rndvector != NULL)
312 isc_mem_put(mctx, hctx->rndvector, hctx->vectorlen);
313
314 UNLOCK(&hctx->lock);
315
316 DESTROYLOCK(&hctx->lock);
317
318 memset(hctx, 0, sizeof(isc_hash_t));
319 isc_mem_put(mctx, hctx, sizeof(isc_hash_t));
320 isc_mem_detach(&mctx);
321 }
322
323 void
isc_hash_ctxdetach(isc_hash_t ** hctxp)324 isc_hash_ctxdetach(isc_hash_t **hctxp) {
325 isc_hash_t *hctx;
326 unsigned int refs;
327
328 REQUIRE(hctxp != NULL && VALID_HASH(*hctxp));
329 hctx = *hctxp;
330
331 isc_refcount_decrement(&hctx->refcnt, &refs);
332 if (refs == 0)
333 destroy(&hctx);
334
335 *hctxp = NULL;
336 }
337
338 void
isc_hash_destroy(void)339 isc_hash_destroy(void) {
340 unsigned int refs;
341
342 INSIST(hash != NULL && VALID_HASH(hash));
343
344 isc_refcount_decrement(&hash->refcnt, &refs);
345 INSIST(refs == 0);
346
347 destroy(&hash);
348 }
349
350 static inline unsigned int
hash_calc(isc_hash_t * hctx,const unsigned char * key,unsigned int keylen,isc_boolean_t case_sensitive)351 hash_calc(isc_hash_t *hctx, const unsigned char *key, unsigned int keylen,
352 isc_boolean_t case_sensitive)
353 {
354 hash_accum_t partial_sum = 0;
355 hash_random_t *p = hctx->rndvector;
356 unsigned int i = 0;
357
358 /* Make it sure that the hash context is initialized. */
359 if (hctx->initialized == ISC_FALSE)
360 isc_hash_ctxinit(hctx);
361
362 if (case_sensitive) {
363 for (i = 0; i < keylen; i++)
364 partial_sum += key[i] * (hash_accum_t)p[i];
365 } else {
366 for (i = 0; i < keylen; i++)
367 partial_sum += maptolower[key[i]] * (hash_accum_t)p[i];
368 }
369
370 partial_sum += p[i];
371
372 return ((unsigned int)(partial_sum % PRIME32));
373 }
374
375 unsigned int
isc_hash_ctxcalc(isc_hash_t * hctx,const unsigned char * key,unsigned int keylen,isc_boolean_t case_sensitive)376 isc_hash_ctxcalc(isc_hash_t *hctx, const unsigned char *key,
377 unsigned int keylen, isc_boolean_t case_sensitive)
378 {
379 REQUIRE(hctx != NULL && VALID_HASH(hctx));
380 REQUIRE(keylen <= hctx->limit);
381
382 return (hash_calc(hctx, key, keylen, case_sensitive));
383 }
384
385 unsigned int
isc_hash_calc(const unsigned char * key,unsigned int keylen,isc_boolean_t case_sensitive)386 isc_hash_calc(const unsigned char *key, unsigned int keylen,
387 isc_boolean_t case_sensitive)
388 {
389 INSIST(hash != NULL && VALID_HASH(hash));
390 REQUIRE(keylen <= hash->limit);
391
392 return (hash_calc(hash, key, keylen, case_sensitive));
393 }
394
395 void
isc__hash_setvec(const isc_uint16_t * vec)396 isc__hash_setvec(const isc_uint16_t *vec) {
397 int i;
398 hash_random_t *p;
399
400 if (hash == NULL)
401 return;
402
403 p = hash->rndvector;
404 for (i = 0; i < 256; i++) {
405 p[i] = vec[i];
406 }
407 }
408