1 /*
2 * Copyright (C) 2004-2007, 2009 Internet Systems Consortium, Inc. ("ISC")
3 * Copyright (C) 2003 Internet Software Consortium.
4 *
5 * Permission to use, copy, modify, and/or 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.
8 *
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.
16 */
17
18 /* $Id: hash.c,v 1.16 2009/09/01 00:22:28 jinmei Exp $ */
19
20 /*! \file
21 * Some portion of this code was derived from universal hash function
22 * libraries of Rice University.
23 \section license UH Universal Hashing Library
24
25 Copyright ((c)) 2002, Rice University
26 All rights reserved.
27
28 Redistribution and use in source and binary forms, with or without
29 modification, are permitted provided that the following conditions are
30 met:
31
32 * Redistributions of source code must retain the above copyright
33 notice, this list of conditions and the following disclaimer.
34
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.
39
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.
43
44
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.
57 */
58
59 #include <config.h>
60
61 #include <isc/entropy.h>
62 #include <isc/hash.h>
63 #include <isc/mem.h>
64 #include <isc/magic.h>
65 #include <isc/mutex.h>
66 #include <isc/once.h>
67 #include <isc/random.h>
68 #include <isc/refcount.h>
69 #include <isc/string.h>
70 #include <isc/util.h>
71
72 #define HASH_MAGIC ISC_MAGIC('H', 'a', 's', 'h')
73 #define VALID_HASH(h) ISC_MAGIC_VALID((h), HASH_MAGIC)
74
75 /*%
76 * A large 32-bit prime number that specifies the range of the hash output.
77 */
78 #define PRIME32 0xFFFFFFFB /* 2^32 - 5 */
79
80 /*@{*/
81 /*%
82 * Types of random seed and hash accumulator. Perhaps they can be system
83 * dependent.
84 */
85 typedef isc_uint32_t hash_accum_t;
86 typedef isc_uint16_t hash_random_t;
87 /*@}*/
88
89 /*% isc hash structure */
90 struct isc_hash {
91 unsigned int magic;
92 isc_mem_t *mctx;
93 isc_mutex_t lock;
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 */
100 };
101
102 static isc_mutex_t createlock;
103 static isc_once_t once = ISC_ONCE_INIT;
104 static isc_hash_t *hash = NULL;
105
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
139 };
140
141 isc_result_t
isc_hash_ctxcreate(isc_mem_t * mctx,isc_entropy_t * entropy,unsigned int limit,isc_hash_t ** hctxp)142 isc_hash_ctxcreate(isc_mem_t *mctx, isc_entropy_t *entropy,
143 unsigned int limit, isc_hash_t **hctxp)
144 {
145 isc_result_t result;
146 isc_hash_t *hctx;
147 size_t vlen;
148 hash_random_t *rv;
149 hash_accum_t overflow_limit;
150
151 REQUIRE(mctx != NULL);
152 REQUIRE(hctxp != NULL && *hctxp == NULL);
153
154 /*
155 * Overflow check. Since our implementation only does a modulo
156 * operation at the last stage of hash calculation, the accumulator
157 * must not overflow.
158 */
159 overflow_limit =
160 1 << (((sizeof(hash_accum_t) - sizeof(hash_random_t))) * 8);
161 if (overflow_limit < (limit + 1) * 0xff)
162 return (ISC_R_RANGE);
163
164 hctx = isc_mem_get(mctx, sizeof(isc_hash_t));
165 if (hctx == NULL)
166 return (ISC_R_NOMEMORY);
167
168 vlen = sizeof(hash_random_t) * (limit + 1);
169 rv = isc_mem_get(mctx, vlen);
170 if (rv == NULL) {
171 result = ISC_R_NOMEMORY;
172 goto errout;
173 }
174
175 /*
176 * We need a lock.
177 */
178 result = isc_mutex_init(&hctx->lock);
179 if (result != ISC_R_SUCCESS)
180 goto errout;
181
182 /*
183 * From here down, no failures will/can occur.
184 */
185 hctx->magic = HASH_MAGIC;
186 hctx->mctx = NULL;
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)
191 goto cleanup_lock;
192 hctx->entropy = NULL;
193 hctx->limit = limit;
194 hctx->vectorlen = vlen;
195 hctx->rndvector = rv;
196
197 #ifdef BIND9
198 if (entropy != NULL)
199 isc_entropy_attach(entropy, &hctx->entropy);
200 #else
201 UNUSED(entropy);
202 #endif
203
204 *hctxp = hctx;
205 return (ISC_R_SUCCESS);
206
207 cleanup_lock:
208 DESTROYLOCK(&hctx->lock);
209 errout:
210 isc_mem_put(mctx, hctx, sizeof(isc_hash_t));
211 if (rv != NULL)
212 isc_mem_put(mctx, rv, vlen);
213
214 return (result);
215 }
216
217 static void
initialize_lock(void)218 initialize_lock(void) {
219 RUNTIME_CHECK(isc_mutex_init(&createlock) == ISC_R_SUCCESS);
220 }
221
222 isc_result_t
isc_hash_create(isc_mem_t * mctx,isc_entropy_t * entropy,size_t limit)223 isc_hash_create(isc_mem_t *mctx, isc_entropy_t *entropy, size_t limit) {
224 isc_result_t result = ISC_R_SUCCESS;
225
226 REQUIRE(mctx != NULL);
227 INSIST(hash == NULL);
228
229 RUNTIME_CHECK(isc_once_do(&once, initialize_lock) == ISC_R_SUCCESS);
230
231 LOCK(&createlock);
232
233 if (hash == NULL)
234 result = isc_hash_ctxcreate(mctx, entropy, limit, &hash);
235
236 UNLOCK(&createlock);
237
238 return (result);
239 }
240
241 void
isc_hash_ctxinit(isc_hash_t * hctx)242 isc_hash_ctxinit(isc_hash_t *hctx) {
243 LOCK(&hctx->lock);
244
245 if (hctx->initialized == ISC_TRUE)
246 goto out;
247
248 if (hctx->entropy) {
249 #ifdef BIND9
250 isc_result_t result;
251
252 result = isc_entropy_getdata(hctx->entropy,
253 hctx->rndvector, hctx->vectorlen,
254 NULL, 0);
255 INSIST(result == ISC_R_SUCCESS);
256 #else
257 INSIST(0);
258 #endif
259 } else {
260 isc_uint32_t pr;
261 unsigned int i, copylen;
262 unsigned char *p;
263
264 p = (unsigned char *)hctx->rndvector;
265 for (i = 0; i < hctx->vectorlen; i += copylen, p += copylen) {
266 isc_random_get(&pr);
267 if (i + sizeof(pr) <= hctx->vectorlen)
268 copylen = sizeof(pr);
269 else
270 copylen = hctx->vectorlen - i;
271
272 memcpy(p, &pr, copylen);
273 }
274 INSIST(p == (unsigned char *)hctx->rndvector +
275 hctx->vectorlen);
276 }
277
278 hctx->initialized = ISC_TRUE;
279
280 out:
281 UNLOCK(&hctx->lock);
282 }
283
284 void
isc_hash_init()285 isc_hash_init() {
286 INSIST(hash != NULL && VALID_HASH(hash));
287
288 isc_hash_ctxinit(hash);
289 }
290
291 void
isc_hash_ctxattach(isc_hash_t * hctx,isc_hash_t ** hctxp)292 isc_hash_ctxattach(isc_hash_t *hctx, isc_hash_t **hctxp) {
293 REQUIRE(VALID_HASH(hctx));
294 REQUIRE(hctxp != NULL && *hctxp == NULL);
295
296 isc_refcount_increment(&hctx->refcnt, NULL);
297 *hctxp = hctx;
298 }
299
300 static void
destroy(isc_hash_t ** hctxp)301 destroy(isc_hash_t **hctxp) {
302 isc_hash_t *hctx;
303 isc_mem_t *mctx;
304 unsigned char canary0[4], canary1[4];
305
306 REQUIRE(hctxp != NULL && *hctxp != NULL);
307 hctx = *hctxp;
308 *hctxp = NULL;
309
310 LOCK(&hctx->lock);
311
312 isc_refcount_destroy(&hctx->refcnt);
313
314 mctx = hctx->mctx;
315 #ifdef BIND9
316 if (hctx->entropy != NULL)
317 isc_entropy_detach(&hctx->entropy);
318 #endif
319 if (hctx->rndvector != NULL)
320 isc_mem_put(mctx, hctx->rndvector, hctx->vectorlen);
321
322 UNLOCK(&hctx->lock);
323
324 DESTROYLOCK(&hctx->lock);
325
326 memcpy(canary0, hctx + 1, sizeof(canary0));
327 memset(hctx, 0, sizeof(isc_hash_t));
328 memcpy(canary1, hctx + 1, sizeof(canary1));
329 INSIST(memcmp(canary0, canary1, sizeof(canary0)) == 0);
330 isc_mem_put(mctx, hctx, sizeof(isc_hash_t));
331 isc_mem_detach(&mctx);
332 }
333
334 void
isc_hash_ctxdetach(isc_hash_t ** hctxp)335 isc_hash_ctxdetach(isc_hash_t **hctxp) {
336 isc_hash_t *hctx;
337 unsigned int refs;
338
339 REQUIRE(hctxp != NULL && VALID_HASH(*hctxp));
340 hctx = *hctxp;
341
342 isc_refcount_decrement(&hctx->refcnt, &refs);
343 if (refs == 0)
344 destroy(&hctx);
345
346 *hctxp = NULL;
347 }
348
349 void
isc_hash_destroy()350 isc_hash_destroy() {
351 unsigned int refs;
352
353 INSIST(hash != NULL && VALID_HASH(hash));
354
355 isc_refcount_decrement(&hash->refcnt, &refs);
356 INSIST(refs == 0);
357
358 destroy(&hash);
359 }
360
361 static inline unsigned int
hash_calc(isc_hash_t * hctx,const unsigned char * key,unsigned int keylen,isc_boolean_t case_sensitive)362 hash_calc(isc_hash_t *hctx, const unsigned char *key, unsigned int keylen,
363 isc_boolean_t case_sensitive)
364 {
365 hash_accum_t partial_sum = 0;
366 hash_random_t *p = hctx->rndvector;
367 unsigned int i = 0;
368
369 /* Make it sure that the hash context is initialized. */
370 if (hctx->initialized == ISC_FALSE)
371 isc_hash_ctxinit(hctx);
372
373 if (case_sensitive) {
374 for (i = 0; i < keylen; i++)
375 partial_sum += key[i] * (hash_accum_t)p[i];
376 } else {
377 for (i = 0; i < keylen; i++)
378 partial_sum += maptolower[key[i]] * (hash_accum_t)p[i];
379 }
380
381 partial_sum += p[i];
382
383 return ((unsigned int)(partial_sum % PRIME32));
384 }
385
386 unsigned int
isc_hash_ctxcalc(isc_hash_t * hctx,const unsigned char * key,unsigned int keylen,isc_boolean_t case_sensitive)387 isc_hash_ctxcalc(isc_hash_t *hctx, const unsigned char *key,
388 unsigned int keylen, isc_boolean_t case_sensitive)
389 {
390 REQUIRE(hctx != NULL && VALID_HASH(hctx));
391 REQUIRE(keylen <= hctx->limit);
392
393 return (hash_calc(hctx, key, keylen, case_sensitive));
394 }
395
396 unsigned int
isc_hash_calc(const unsigned char * key,unsigned int keylen,isc_boolean_t case_sensitive)397 isc_hash_calc(const unsigned char *key, unsigned int keylen,
398 isc_boolean_t case_sensitive)
399 {
400 INSIST(hash != NULL && VALID_HASH(hash));
401 REQUIRE(keylen <= hash->limit);
402
403 return (hash_calc(hash, key, keylen, case_sensitive));
404 }
405