1 /* $NetBSD: hash.c,v 1.1.1.1 2009/12/13 16:54:14 kardel 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 1.13.332.3 2009/05/07 23:47:12 tbox 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 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 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 216 initialize_lock(void) { 217 RUNTIME_CHECK(isc_mutex_init(&createlock) == ISC_R_SUCCESS); 218 } 219 220 isc_result_t 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 240 isc_hash_ctxinit(isc_hash_t *hctx) { 241 isc_result_t result; 242 243 LOCK(&hctx->lock); 244 245 if (hctx->initialized == ISC_TRUE) 246 goto out; 247 248 if (hctx->entropy) { 249 result = isc_entropy_getdata(hctx->entropy, 250 hctx->rndvector, hctx->vectorlen, 251 NULL, 0); 252 INSIST(result == ISC_R_SUCCESS); 253 } else { 254 isc_uint32_t pr; 255 unsigned int i, copylen; 256 unsigned char *p; 257 258 p = (unsigned char *)hctx->rndvector; 259 for (i = 0; i < hctx->vectorlen; i += copylen, p += copylen) { 260 isc_random_get(&pr); 261 if (i + sizeof(pr) <= hctx->vectorlen) 262 copylen = sizeof(pr); 263 else 264 copylen = hctx->vectorlen - i; 265 266 memcpy(p, &pr, copylen); 267 } 268 INSIST(p == (unsigned char *)hctx->rndvector + 269 hctx->vectorlen); 270 } 271 272 hctx->initialized = ISC_TRUE; 273 274 out: 275 UNLOCK(&hctx->lock); 276 } 277 278 void 279 isc_hash_init() { 280 INSIST(hash != NULL && VALID_HASH(hash)); 281 282 isc_hash_ctxinit(hash); 283 } 284 285 void 286 isc_hash_ctxattach(isc_hash_t *hctx, isc_hash_t **hctxp) { 287 REQUIRE(VALID_HASH(hctx)); 288 REQUIRE(hctxp != NULL && *hctxp == NULL); 289 290 isc_refcount_increment(&hctx->refcnt, NULL); 291 *hctxp = hctx; 292 } 293 294 static void 295 destroy(isc_hash_t **hctxp) { 296 isc_hash_t *hctx; 297 isc_mem_t *mctx; 298 299 REQUIRE(hctxp != NULL && *hctxp != NULL); 300 hctx = *hctxp; 301 *hctxp = NULL; 302 303 LOCK(&hctx->lock); 304 305 isc_refcount_destroy(&hctx->refcnt); 306 307 mctx = hctx->mctx; 308 if (hctx->entropy != NULL) 309 isc_entropy_detach(&hctx->entropy); 310 if (hctx->rndvector != NULL) 311 isc_mem_put(mctx, hctx->rndvector, hctx->vectorlen); 312 313 UNLOCK(&hctx->lock); 314 315 DESTROYLOCK(&hctx->lock); 316 317 memset(hctx, 0, sizeof(isc_hash_t)); 318 isc_mem_put(mctx, hctx, sizeof(isc_hash_t)); 319 isc_mem_detach(&mctx); 320 } 321 322 void 323 isc_hash_ctxdetach(isc_hash_t **hctxp) { 324 isc_hash_t *hctx; 325 unsigned int refs; 326 327 REQUIRE(hctxp != NULL && VALID_HASH(*hctxp)); 328 hctx = *hctxp; 329 330 isc_refcount_decrement(&hctx->refcnt, &refs); 331 if (refs == 0) 332 destroy(&hctx); 333 334 *hctxp = NULL; 335 } 336 337 void 338 isc_hash_destroy() { 339 unsigned int refs; 340 341 INSIST(hash != NULL && VALID_HASH(hash)); 342 343 isc_refcount_decrement(&hash->refcnt, &refs); 344 INSIST(refs == 0); 345 346 destroy(&hash); 347 } 348 349 static inline unsigned int 350 hash_calc(isc_hash_t *hctx, const unsigned char *key, unsigned int keylen, 351 isc_boolean_t case_sensitive) 352 { 353 hash_accum_t partial_sum = 0; 354 hash_random_t *p = hctx->rndvector; 355 unsigned int i = 0; 356 357 /* Make it sure that the hash context is initialized. */ 358 if (hctx->initialized == ISC_FALSE) 359 isc_hash_ctxinit(hctx); 360 361 if (case_sensitive) { 362 for (i = 0; i < keylen; i++) 363 partial_sum += key[i] * (hash_accum_t)p[i]; 364 } else { 365 for (i = 0; i < keylen; i++) 366 partial_sum += maptolower[key[i]] * (hash_accum_t)p[i]; 367 } 368 369 partial_sum += p[i]; 370 371 return ((unsigned int)(partial_sum % PRIME32)); 372 } 373 374 unsigned int 375 isc_hash_ctxcalc(isc_hash_t *hctx, const unsigned char *key, 376 unsigned int keylen, isc_boolean_t case_sensitive) 377 { 378 REQUIRE(hctx != NULL && VALID_HASH(hctx)); 379 REQUIRE(keylen <= hctx->limit); 380 381 return (hash_calc(hctx, key, keylen, case_sensitive)); 382 } 383 384 unsigned int 385 isc_hash_calc(const unsigned char *key, unsigned int keylen, 386 isc_boolean_t case_sensitive) 387 { 388 INSIST(hash != NULL && VALID_HASH(hash)); 389 REQUIRE(keylen <= hash->limit); 390 391 return (hash_calc(hash, key, keylen, case_sensitive)); 392 } 393