1 /* $NetBSD: hash.c,v 1.6 2020/05/25 20:47:20 christos Exp $ */
2
3 /*
4 * Copyright (C) 2004-2007, 2009 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 unsigned int 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,unsigned int limit,isc_hash_t ** hctxp)144 isc_hash_ctxcreate(isc_mem_t *mctx, isc_entropy_t *entropy,
145 unsigned int 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 #ifdef BIND9
200 if (entropy != NULL)
201 isc_entropy_attach(entropy, &hctx->entropy);
202 #else
203 UNUSED(entropy);
204 #endif
205
206 *hctxp = hctx;
207 return (ISC_R_SUCCESS);
208
209 cleanup_lock:
210 DESTROYLOCK(&hctx->lock);
211 errout:
212 isc_mem_put(mctx, hctx, sizeof(isc_hash_t));
213 if (rv != NULL)
214 isc_mem_put(mctx, rv, vlen);
215
216 return (result);
217 }
218
219 static void
initialize_lock(void)220 initialize_lock(void) {
221 RUNTIME_CHECK(isc_mutex_init(&createlock) == ISC_R_SUCCESS);
222 }
223
224 isc_result_t
isc_hash_create(isc_mem_t * mctx,isc_entropy_t * entropy,size_t limit)225 isc_hash_create(isc_mem_t *mctx, isc_entropy_t *entropy, size_t limit) {
226 isc_result_t result = ISC_R_SUCCESS;
227
228 REQUIRE(mctx != NULL);
229 INSIST(hash == NULL);
230
231 RUNTIME_CHECK(isc_once_do(&once, initialize_lock) == ISC_R_SUCCESS);
232
233 LOCK(&createlock);
234
235 if (hash == NULL)
236 result = isc_hash_ctxcreate(mctx, entropy, limit, &hash);
237
238 UNLOCK(&createlock);
239
240 return (result);
241 }
242
243 void
isc_hash_ctxinit(isc_hash_t * hctx)244 isc_hash_ctxinit(isc_hash_t *hctx) {
245 LOCK(&hctx->lock);
246
247 if (hctx->initialized == ISC_TRUE)
248 goto out;
249
250 if (hctx->entropy) {
251 #ifdef BIND9
252 isc_result_t result;
253
254 result = isc_entropy_getdata(hctx->entropy,
255 hctx->rndvector, hctx->vectorlen,
256 NULL, 0);
257 INSIST(result == ISC_R_SUCCESS);
258 #else
259 INSIST(0);
260 #endif
261 } else {
262 isc_uint32_t pr;
263 unsigned int i, copylen;
264 unsigned char *p;
265
266 p = (unsigned char *)hctx->rndvector;
267 for (i = 0; i < hctx->vectorlen; i += copylen, p += copylen) {
268 isc_random_get(&pr);
269 if (i + sizeof(pr) <= hctx->vectorlen)
270 copylen = sizeof(pr);
271 else
272 copylen = hctx->vectorlen - i;
273
274 memcpy(p, &pr, copylen);
275 }
276 INSIST(p == (unsigned char *)hctx->rndvector +
277 hctx->vectorlen);
278 }
279
280 hctx->initialized = ISC_TRUE;
281
282 out:
283 UNLOCK(&hctx->lock);
284 }
285
286 void
isc_hash_init()287 isc_hash_init() {
288 INSIST(hash != NULL && VALID_HASH(hash));
289
290 isc_hash_ctxinit(hash);
291 }
292
293 void
isc_hash_ctxattach(isc_hash_t * hctx,isc_hash_t ** hctxp)294 isc_hash_ctxattach(isc_hash_t *hctx, isc_hash_t **hctxp) {
295 REQUIRE(VALID_HASH(hctx));
296 REQUIRE(hctxp != NULL && *hctxp == NULL);
297
298 isc_refcount_increment(&hctx->refcnt, NULL);
299 *hctxp = hctx;
300 }
301
302 static void
destroy(isc_hash_t ** hctxp)303 destroy(isc_hash_t **hctxp) {
304 isc_hash_t *hctx;
305 isc_mem_t *mctx;
306 unsigned char canary0[4], canary1[4];
307
308 REQUIRE(hctxp != NULL && *hctxp != NULL);
309 hctx = *hctxp;
310 *hctxp = NULL;
311
312 LOCK(&hctx->lock);
313
314 isc_refcount_destroy(&hctx->refcnt);
315
316 mctx = hctx->mctx;
317 #ifdef BIND9
318 if (hctx->entropy != NULL)
319 isc_entropy_detach(&hctx->entropy);
320 #endif
321 if (hctx->rndvector != NULL)
322 isc_mem_put(mctx, hctx->rndvector, hctx->vectorlen);
323
324 UNLOCK(&hctx->lock);
325
326 DESTROYLOCK(&hctx->lock);
327
328 memcpy(canary0, hctx + 1, sizeof(canary0));
329 memset(hctx, 0, sizeof(isc_hash_t));
330 memcpy(canary1, hctx + 1, sizeof(canary1));
331 INSIST(memcmp(canary0, canary1, sizeof(canary0)) == 0);
332 isc_mem_put(mctx, hctx, sizeof(isc_hash_t));
333 isc_mem_detach(&mctx);
334 }
335
336 void
isc_hash_ctxdetach(isc_hash_t ** hctxp)337 isc_hash_ctxdetach(isc_hash_t **hctxp) {
338 isc_hash_t *hctx;
339 unsigned int refs;
340
341 REQUIRE(hctxp != NULL && VALID_HASH(*hctxp));
342 hctx = *hctxp;
343
344 isc_refcount_decrement(&hctx->refcnt, &refs);
345 if (refs == 0)
346 destroy(&hctx);
347
348 *hctxp = NULL;
349 }
350
351 void
isc_hash_destroy()352 isc_hash_destroy() {
353 unsigned int refs;
354
355 INSIST(hash != NULL && VALID_HASH(hash));
356
357 isc_refcount_decrement(&hash->refcnt, &refs);
358 INSIST(refs == 0);
359
360 destroy(&hash);
361 }
362
363 static inline unsigned int
hash_calc(isc_hash_t * hctx,const unsigned char * key,unsigned int keylen,isc_boolean_t case_sensitive)364 hash_calc(isc_hash_t *hctx, const unsigned char *key, unsigned int keylen,
365 isc_boolean_t case_sensitive)
366 {
367 hash_accum_t partial_sum = 0;
368 hash_random_t *p = hctx->rndvector;
369 unsigned int i = 0;
370
371 /* Make it sure that the hash context is initialized. */
372 if (hctx->initialized == ISC_FALSE)
373 isc_hash_ctxinit(hctx);
374
375 if (case_sensitive) {
376 for (i = 0; i < keylen; i++)
377 partial_sum += key[i] * (hash_accum_t)p[i];
378 } else {
379 for (i = 0; i < keylen; i++)
380 partial_sum += maptolower[key[i]] * (hash_accum_t)p[i];
381 }
382
383 partial_sum += p[i];
384
385 return ((unsigned int)(partial_sum % PRIME32));
386 }
387
388 unsigned int
isc_hash_ctxcalc(isc_hash_t * hctx,const unsigned char * key,unsigned int keylen,isc_boolean_t case_sensitive)389 isc_hash_ctxcalc(isc_hash_t *hctx, const unsigned char *key,
390 unsigned int keylen, isc_boolean_t case_sensitive)
391 {
392 REQUIRE(hctx != NULL && VALID_HASH(hctx));
393 REQUIRE(keylen <= hctx->limit);
394
395 return (hash_calc(hctx, key, keylen, case_sensitive));
396 }
397
398 unsigned int
isc_hash_calc(const unsigned char * key,unsigned int keylen,isc_boolean_t case_sensitive)399 isc_hash_calc(const unsigned char *key, unsigned int keylen,
400 isc_boolean_t case_sensitive)
401 {
402 INSIST(hash != NULL && VALID_HASH(hash));
403 REQUIRE(keylen <= hash->limit);
404
405 return (hash_calc(hash, key, keylen, case_sensitive));
406 }
407