Annotation of embedaddon/ntp/lib/isc/hash.c, revision 1.1
1.1 ! misho 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 1.13.332.3 2009/05/07 23:47:12 tbox 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
! 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: if (entropy != NULL)
! 198: isc_entropy_attach(entropy, &hctx->entropy);
! 199:
! 200: *hctxp = hctx;
! 201: return (ISC_R_SUCCESS);
! 202:
! 203: cleanup_lock:
! 204: DESTROYLOCK(&hctx->lock);
! 205: errout:
! 206: isc_mem_put(mctx, hctx, sizeof(isc_hash_t));
! 207: if (rv != NULL)
! 208: isc_mem_put(mctx, rv, vlen);
! 209:
! 210: return (result);
! 211: }
! 212:
! 213: static void
! 214: initialize_lock(void) {
! 215: RUNTIME_CHECK(isc_mutex_init(&createlock) == ISC_R_SUCCESS);
! 216: }
! 217:
! 218: isc_result_t
! 219: isc_hash_create(isc_mem_t *mctx, isc_entropy_t *entropy, size_t limit) {
! 220: isc_result_t result = ISC_R_SUCCESS;
! 221:
! 222: REQUIRE(mctx != NULL);
! 223: INSIST(hash == NULL);
! 224:
! 225: RUNTIME_CHECK(isc_once_do(&once, initialize_lock) == ISC_R_SUCCESS);
! 226:
! 227: LOCK(&createlock);
! 228:
! 229: if (hash == NULL)
! 230: result = isc_hash_ctxcreate(mctx, entropy, limit, &hash);
! 231:
! 232: UNLOCK(&createlock);
! 233:
! 234: return (result);
! 235: }
! 236:
! 237: void
! 238: isc_hash_ctxinit(isc_hash_t *hctx) {
! 239: isc_result_t result;
! 240:
! 241: LOCK(&hctx->lock);
! 242:
! 243: if (hctx->initialized == ISC_TRUE)
! 244: goto out;
! 245:
! 246: if (hctx->entropy) {
! 247: result = isc_entropy_getdata(hctx->entropy,
! 248: hctx->rndvector, hctx->vectorlen,
! 249: NULL, 0);
! 250: INSIST(result == ISC_R_SUCCESS);
! 251: } else {
! 252: isc_uint32_t pr;
! 253: unsigned int i, copylen;
! 254: unsigned char *p;
! 255:
! 256: p = (unsigned char *)hctx->rndvector;
! 257: for (i = 0; i < hctx->vectorlen; i += copylen, p += copylen) {
! 258: isc_random_get(&pr);
! 259: if (i + sizeof(pr) <= hctx->vectorlen)
! 260: copylen = sizeof(pr);
! 261: else
! 262: copylen = hctx->vectorlen - i;
! 263:
! 264: memcpy(p, &pr, copylen);
! 265: }
! 266: INSIST(p == (unsigned char *)hctx->rndvector +
! 267: hctx->vectorlen);
! 268: }
! 269:
! 270: hctx->initialized = ISC_TRUE;
! 271:
! 272: out:
! 273: UNLOCK(&hctx->lock);
! 274: }
! 275:
! 276: void
! 277: isc_hash_init() {
! 278: INSIST(hash != NULL && VALID_HASH(hash));
! 279:
! 280: isc_hash_ctxinit(hash);
! 281: }
! 282:
! 283: void
! 284: isc_hash_ctxattach(isc_hash_t *hctx, isc_hash_t **hctxp) {
! 285: REQUIRE(VALID_HASH(hctx));
! 286: REQUIRE(hctxp != NULL && *hctxp == NULL);
! 287:
! 288: isc_refcount_increment(&hctx->refcnt, NULL);
! 289: *hctxp = hctx;
! 290: }
! 291:
! 292: static void
! 293: destroy(isc_hash_t **hctxp) {
! 294: isc_hash_t *hctx;
! 295: isc_mem_t *mctx;
! 296:
! 297: REQUIRE(hctxp != NULL && *hctxp != NULL);
! 298: hctx = *hctxp;
! 299: *hctxp = NULL;
! 300:
! 301: LOCK(&hctx->lock);
! 302:
! 303: isc_refcount_destroy(&hctx->refcnt);
! 304:
! 305: mctx = hctx->mctx;
! 306: if (hctx->entropy != NULL)
! 307: isc_entropy_detach(&hctx->entropy);
! 308: if (hctx->rndvector != NULL)
! 309: isc_mem_put(mctx, hctx->rndvector, hctx->vectorlen);
! 310:
! 311: UNLOCK(&hctx->lock);
! 312:
! 313: DESTROYLOCK(&hctx->lock);
! 314:
! 315: memset(hctx, 0, sizeof(isc_hash_t));
! 316: isc_mem_put(mctx, hctx, sizeof(isc_hash_t));
! 317: isc_mem_detach(&mctx);
! 318: }
! 319:
! 320: void
! 321: isc_hash_ctxdetach(isc_hash_t **hctxp) {
! 322: isc_hash_t *hctx;
! 323: unsigned int refs;
! 324:
! 325: REQUIRE(hctxp != NULL && VALID_HASH(*hctxp));
! 326: hctx = *hctxp;
! 327:
! 328: isc_refcount_decrement(&hctx->refcnt, &refs);
! 329: if (refs == 0)
! 330: destroy(&hctx);
! 331:
! 332: *hctxp = NULL;
! 333: }
! 334:
! 335: void
! 336: isc_hash_destroy() {
! 337: unsigned int refs;
! 338:
! 339: INSIST(hash != NULL && VALID_HASH(hash));
! 340:
! 341: isc_refcount_decrement(&hash->refcnt, &refs);
! 342: INSIST(refs == 0);
! 343:
! 344: destroy(&hash);
! 345: }
! 346:
! 347: static inline unsigned int
! 348: hash_calc(isc_hash_t *hctx, const unsigned char *key, unsigned int keylen,
! 349: isc_boolean_t case_sensitive)
! 350: {
! 351: hash_accum_t partial_sum = 0;
! 352: hash_random_t *p = hctx->rndvector;
! 353: unsigned int i = 0;
! 354:
! 355: /* Make it sure that the hash context is initialized. */
! 356: if (hctx->initialized == ISC_FALSE)
! 357: isc_hash_ctxinit(hctx);
! 358:
! 359: if (case_sensitive) {
! 360: for (i = 0; i < keylen; i++)
! 361: partial_sum += key[i] * (hash_accum_t)p[i];
! 362: } else {
! 363: for (i = 0; i < keylen; i++)
! 364: partial_sum += maptolower[key[i]] * (hash_accum_t)p[i];
! 365: }
! 366:
! 367: partial_sum += p[i];
! 368:
! 369: return ((unsigned int)(partial_sum % PRIME32));
! 370: }
! 371:
! 372: unsigned int
! 373: isc_hash_ctxcalc(isc_hash_t *hctx, const unsigned char *key,
! 374: unsigned int keylen, isc_boolean_t case_sensitive)
! 375: {
! 376: REQUIRE(hctx != NULL && VALID_HASH(hctx));
! 377: REQUIRE(keylen <= hctx->limit);
! 378:
! 379: return (hash_calc(hctx, key, keylen, case_sensitive));
! 380: }
! 381:
! 382: unsigned int
! 383: isc_hash_calc(const unsigned char *key, unsigned int keylen,
! 384: isc_boolean_t case_sensitive)
! 385: {
! 386: INSIST(hash != NULL && VALID_HASH(hash));
! 387: REQUIRE(keylen <= hash->limit);
! 388:
! 389: return (hash_calc(hash, key, keylen, case_sensitive));
! 390: }
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