/contrib/bind9/lib/isc/hash.c
https://bitbucket.org/freebsd/freebsd-head/ · C · 404 lines · 261 code · 66 blank · 77 comment · 61 complexity · 98ad5dcb59b8bc6a34c0ec844d73af6c MD5 · raw file
- /*
- * Copyright (C) 2004-2007, 2009 Internet Systems Consortium, Inc. ("ISC")
- * Copyright (C) 2003 Internet Software Consortium.
- *
- * Permission to use, copy, modify, and/or distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies.
- *
- * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
- * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
- * AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
- * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
- * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
- * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
- * PERFORMANCE OF THIS SOFTWARE.
- */
- /* $Id: hash.c,v 1.16 2009/09/01 00:22:28 jinmei Exp $ */
- /*! \file
- * Some portion of this code was derived from universal hash function
- * libraries of Rice University.
- \section license UH Universal Hashing Library
- Copyright ((c)) 2002, Rice University
- All rights reserved.
- Redistribution and use in source and binary forms, with or without
- modification, are permitted provided that the following conditions are
- met:
- * Redistributions of source code must retain the above copyright
- notice, this list of conditions and the following disclaimer.
- * Redistributions in binary form must reproduce the above
- copyright notice, this list of conditions and the following
- disclaimer in the documentation and/or other materials provided
- with the distribution.
- * Neither the name of Rice University (RICE) nor the names of its
- contributors may be used to endorse or promote products derived
- from this software without specific prior written permission.
- This software is provided by RICE and the contributors on an "as is"
- basis, without any representations or warranties of any kind, express
- or implied including, but not limited to, representations or
- warranties of non-infringement, merchantability or fitness for a
- particular purpose. In no event shall RICE or contributors be liable
- for any direct, indirect, incidental, special, exemplary, or
- consequential damages (including, but not limited to, procurement of
- substitute goods or services; loss of use, data, or profits; or
- business interruption) however caused and on any theory of liability,
- whether in contract, strict liability, or tort (including negligence
- or otherwise) arising in any way out of the use of this software, even
- if advised of the possibility of such damage.
- */
- #include <config.h>
- #include <isc/entropy.h>
- #include <isc/hash.h>
- #include <isc/mem.h>
- #include <isc/magic.h>
- #include <isc/mutex.h>
- #include <isc/once.h>
- #include <isc/random.h>
- #include <isc/refcount.h>
- #include <isc/string.h>
- #include <isc/util.h>
- #define HASH_MAGIC ISC_MAGIC('H', 'a', 's', 'h')
- #define VALID_HASH(h) ISC_MAGIC_VALID((h), HASH_MAGIC)
- /*%
- * A large 32-bit prime number that specifies the range of the hash output.
- */
- #define PRIME32 0xFFFFFFFB /* 2^32 - 5 */
- /*@{*/
- /*%
- * Types of random seed and hash accumulator. Perhaps they can be system
- * dependent.
- */
- typedef isc_uint32_t hash_accum_t;
- typedef isc_uint16_t hash_random_t;
- /*@}*/
- /*% isc hash structure */
- struct isc_hash {
- unsigned int magic;
- isc_mem_t *mctx;
- isc_mutex_t lock;
- isc_boolean_t initialized;
- isc_refcount_t refcnt;
- isc_entropy_t *entropy; /*%< entropy source */
- unsigned int limit; /*%< upper limit of key length */
- size_t vectorlen; /*%< size of the vector below */
- hash_random_t *rndvector; /*%< random vector for universal hashing */
- };
- static isc_mutex_t createlock;
- static isc_once_t once = ISC_ONCE_INIT;
- static isc_hash_t *hash = NULL;
- static unsigned char maptolower[] = {
- 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
- 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
- 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
- 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
- 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
- 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
- 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
- 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
- 0x40, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67,
- 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f,
- 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77,
- 0x78, 0x79, 0x7a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f,
- 0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67,
- 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f,
- 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77,
- 0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f,
- 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
- 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
- 0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97,
- 0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f,
- 0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
- 0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf,
- 0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7,
- 0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf,
- 0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,
- 0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf,
- 0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7,
- 0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf,
- 0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7,
- 0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef,
- 0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
- 0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff
- };
- isc_result_t
- isc_hash_ctxcreate(isc_mem_t *mctx, isc_entropy_t *entropy,
- unsigned int limit, isc_hash_t **hctxp)
- {
- isc_result_t result;
- isc_hash_t *hctx;
- size_t vlen;
- hash_random_t *rv;
- hash_accum_t overflow_limit;
- REQUIRE(mctx != NULL);
- REQUIRE(hctxp != NULL && *hctxp == NULL);
- /*
- * Overflow check. Since our implementation only does a modulo
- * operation at the last stage of hash calculation, the accumulator
- * must not overflow.
- */
- overflow_limit =
- 1 << (((sizeof(hash_accum_t) - sizeof(hash_random_t))) * 8);
- if (overflow_limit < (limit + 1) * 0xff)
- return (ISC_R_RANGE);
- hctx = isc_mem_get(mctx, sizeof(isc_hash_t));
- if (hctx == NULL)
- return (ISC_R_NOMEMORY);
- vlen = sizeof(hash_random_t) * (limit + 1);
- rv = isc_mem_get(mctx, vlen);
- if (rv == NULL) {
- result = ISC_R_NOMEMORY;
- goto errout;
- }
- /*
- * We need a lock.
- */
- result = isc_mutex_init(&hctx->lock);
- if (result != ISC_R_SUCCESS)
- goto errout;
- /*
- * From here down, no failures will/can occur.
- */
- hctx->magic = HASH_MAGIC;
- hctx->mctx = NULL;
- isc_mem_attach(mctx, &hctx->mctx);
- hctx->initialized = ISC_FALSE;
- result = isc_refcount_init(&hctx->refcnt, 1);
- if (result != ISC_R_SUCCESS)
- goto cleanup_lock;
- hctx->entropy = NULL;
- hctx->limit = limit;
- hctx->vectorlen = vlen;
- hctx->rndvector = rv;
- #ifdef BIND9
- if (entropy != NULL)
- isc_entropy_attach(entropy, &hctx->entropy);
- #else
- UNUSED(entropy);
- #endif
- *hctxp = hctx;
- return (ISC_R_SUCCESS);
- cleanup_lock:
- DESTROYLOCK(&hctx->lock);
- errout:
- isc_mem_put(mctx, hctx, sizeof(isc_hash_t));
- if (rv != NULL)
- isc_mem_put(mctx, rv, vlen);
- return (result);
- }
- static void
- initialize_lock(void) {
- RUNTIME_CHECK(isc_mutex_init(&createlock) == ISC_R_SUCCESS);
- }
- isc_result_t
- isc_hash_create(isc_mem_t *mctx, isc_entropy_t *entropy, size_t limit) {
- isc_result_t result = ISC_R_SUCCESS;
- REQUIRE(mctx != NULL);
- INSIST(hash == NULL);
- RUNTIME_CHECK(isc_once_do(&once, initialize_lock) == ISC_R_SUCCESS);
- LOCK(&createlock);
- if (hash == NULL)
- result = isc_hash_ctxcreate(mctx, entropy, limit, &hash);
- UNLOCK(&createlock);
- return (result);
- }
- void
- isc_hash_ctxinit(isc_hash_t *hctx) {
- LOCK(&hctx->lock);
- if (hctx->initialized == ISC_TRUE)
- goto out;
- if (hctx->entropy) {
- #ifdef BIND9
- isc_result_t result;
- result = isc_entropy_getdata(hctx->entropy,
- hctx->rndvector, hctx->vectorlen,
- NULL, 0);
- INSIST(result == ISC_R_SUCCESS);
- #else
- INSIST(0);
- #endif
- } else {
- isc_uint32_t pr;
- unsigned int i, copylen;
- unsigned char *p;
- p = (unsigned char *)hctx->rndvector;
- for (i = 0; i < hctx->vectorlen; i += copylen, p += copylen) {
- isc_random_get(&pr);
- if (i + sizeof(pr) <= hctx->vectorlen)
- copylen = sizeof(pr);
- else
- copylen = hctx->vectorlen - i;
- memcpy(p, &pr, copylen);
- }
- INSIST(p == (unsigned char *)hctx->rndvector +
- hctx->vectorlen);
- }
- hctx->initialized = ISC_TRUE;
- out:
- UNLOCK(&hctx->lock);
- }
- void
- isc_hash_init() {
- INSIST(hash != NULL && VALID_HASH(hash));
- isc_hash_ctxinit(hash);
- }
- void
- isc_hash_ctxattach(isc_hash_t *hctx, isc_hash_t **hctxp) {
- REQUIRE(VALID_HASH(hctx));
- REQUIRE(hctxp != NULL && *hctxp == NULL);
- isc_refcount_increment(&hctx->refcnt, NULL);
- *hctxp = hctx;
- }
- static void
- destroy(isc_hash_t **hctxp) {
- isc_hash_t *hctx;
- isc_mem_t *mctx;
- unsigned char canary0[4], canary1[4];
- REQUIRE(hctxp != NULL && *hctxp != NULL);
- hctx = *hctxp;
- *hctxp = NULL;
- LOCK(&hctx->lock);
- isc_refcount_destroy(&hctx->refcnt);
- mctx = hctx->mctx;
- #ifdef BIND9
- if (hctx->entropy != NULL)
- isc_entropy_detach(&hctx->entropy);
- #endif
- if (hctx->rndvector != NULL)
- isc_mem_put(mctx, hctx->rndvector, hctx->vectorlen);
- UNLOCK(&hctx->lock);
- DESTROYLOCK(&hctx->lock);
- memcpy(canary0, hctx + 1, sizeof(canary0));
- memset(hctx, 0, sizeof(isc_hash_t));
- memcpy(canary1, hctx + 1, sizeof(canary1));
- INSIST(memcmp(canary0, canary1, sizeof(canary0)) == 0);
- isc_mem_put(mctx, hctx, sizeof(isc_hash_t));
- isc_mem_detach(&mctx);
- }
- void
- isc_hash_ctxdetach(isc_hash_t **hctxp) {
- isc_hash_t *hctx;
- unsigned int refs;
- REQUIRE(hctxp != NULL && VALID_HASH(*hctxp));
- hctx = *hctxp;
- isc_refcount_decrement(&hctx->refcnt, &refs);
- if (refs == 0)
- destroy(&hctx);
- *hctxp = NULL;
- }
- void
- isc_hash_destroy() {
- unsigned int refs;
- INSIST(hash != NULL && VALID_HASH(hash));
- isc_refcount_decrement(&hash->refcnt, &refs);
- INSIST(refs == 0);
- destroy(&hash);
- }
- static inline unsigned int
- hash_calc(isc_hash_t *hctx, const unsigned char *key, unsigned int keylen,
- isc_boolean_t case_sensitive)
- {
- hash_accum_t partial_sum = 0;
- hash_random_t *p = hctx->rndvector;
- unsigned int i = 0;
- /* Make it sure that the hash context is initialized. */
- if (hctx->initialized == ISC_FALSE)
- isc_hash_ctxinit(hctx);
- if (case_sensitive) {
- for (i = 0; i < keylen; i++)
- partial_sum += key[i] * (hash_accum_t)p[i];
- } else {
- for (i = 0; i < keylen; i++)
- partial_sum += maptolower[key[i]] * (hash_accum_t)p[i];
- }
- partial_sum += p[i];
- return ((unsigned int)(partial_sum % PRIME32));
- }
- unsigned int
- isc_hash_ctxcalc(isc_hash_t *hctx, const unsigned char *key,
- unsigned int keylen, isc_boolean_t case_sensitive)
- {
- REQUIRE(hctx != NULL && VALID_HASH(hctx));
- REQUIRE(keylen <= hctx->limit);
- return (hash_calc(hctx, key, keylen, case_sensitive));
- }
- unsigned int
- isc_hash_calc(const unsigned char *key, unsigned int keylen,
- isc_boolean_t case_sensitive)
- {
- INSIST(hash != NULL && VALID_HASH(hash));
- REQUIRE(keylen <= hash->limit);
- return (hash_calc(hash, key, keylen, case_sensitive));
- }