hash.c revision 290001
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 25Copyright ((c)) 2002, Rice University 26All rights reserved. 27 28Redistribution and use in source and binary forms, with or without 29modification, are permitted provided that the following conditions are 30met: 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 45This software is provided by RICE and the contributors on an "as is" 46basis, without any representations or warranties of any kind, express 47or implied including, but not limited to, representations or 48warranties of non-infringement, merchantability or fitness for a 49particular purpose. In no event shall RICE or contributors be liable 50for any direct, indirect, incidental, special, exemplary, or 51consequential damages (including, but not limited to, procurement of 52substitute goods or services; loss of use, data, or profits; or 53business interruption) however caused and on any theory of liability, 54whether in contract, strict liability, or tort (including negligence 55or otherwise) arising in any way out of the use of this software, even 56if 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 */ 85typedef isc_uint32_t hash_accum_t; 86typedef isc_uint16_t hash_random_t; 87/*@}*/ 88 89/*% isc hash structure */ 90struct 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 102static isc_mutex_t createlock; 103static isc_once_t once = ISC_ONCE_INIT; 104static isc_hash_t *hash = NULL; 105 106static 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 141isc_result_t 142isc_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 217static void 218initialize_lock(void) { 219 RUNTIME_CHECK(isc_mutex_init(&createlock) == ISC_R_SUCCESS); 220} 221 222isc_result_t 223isc_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 241void 242isc_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 284void 285isc_hash_init() { 286 INSIST(hash != NULL && VALID_HASH(hash)); 287 288 isc_hash_ctxinit(hash); 289} 290 291void 292isc_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 300static void 301destroy(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 334void 335isc_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 349void 350isc_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 361static inline unsigned int 362hash_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 386unsigned int 387isc_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 396unsigned int 397isc_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