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+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
+
+/*! \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 <stdbool.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 uint32_t hash_accum_t;
+typedef uint16_t hash_random_t;
+/*@}*/
+
+/*% isc hash structure */
+struct isc_hash {
+ unsigned int magic;
+ isc_mem_t *mctx;
+ isc_mutex_t lock;
+ bool initialized;
+ isc_refcount_t refcnt;
+ isc_entropy_t *entropy; /*%< entropy source */
+ size_t 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;
+
+LIBISC_EXTERNAL_DATA isc_hash_t *isc_hashctx = 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,
+ size_t 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 = 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;
+
+ if (entropy != NULL)
+ isc_entropy_attach(entropy, &hctx->entropy);
+
+ *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(isc_hashctx == NULL);
+
+ RUNTIME_CHECK(isc_once_do(&once, initialize_lock) == ISC_R_SUCCESS);
+
+ LOCK(&createlock);
+
+ if (isc_hashctx == NULL)
+ result = isc_hash_ctxcreate(mctx, entropy, limit,
+ &isc_hashctx);
+
+ UNLOCK(&createlock);
+
+ return (result);
+}
+
+void
+isc_hash_ctxinit(isc_hash_t *hctx) {
+ LOCK(&hctx->lock);
+
+ if (hctx->initialized == true)
+ goto out;
+
+ if (hctx->entropy != NULL) {
+ isc_result_t result;
+
+ result = isc_entropy_getdata(hctx->entropy,
+ hctx->rndvector,
+ (unsigned int)hctx->vectorlen,
+ NULL, 0);
+ INSIST(result == ISC_R_SUCCESS);
+ } else {
+ uint32_t pr;
+ size_t 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;
+
+ memmove(p, &pr, copylen);
+ }
+ INSIST(p == (unsigned char *)hctx->rndvector +
+ hctx->vectorlen);
+ }
+
+ hctx->initialized = true;
+
+ out:
+ UNLOCK(&hctx->lock);
+}
+
+void
+isc_hash_init(void) {
+ INSIST(isc_hashctx != NULL && VALID_HASH(isc_hashctx));
+
+ isc_hash_ctxinit(isc_hashctx);
+}
+
+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;
+
+ REQUIRE(hctxp != NULL && *hctxp != NULL);
+ hctx = *hctxp;
+ *hctxp = NULL;
+
+ LOCK(&hctx->lock);
+
+ isc_refcount_destroy(&hctx->refcnt);
+
+ mctx = hctx->mctx;
+ if (hctx->entropy != NULL)
+ isc_entropy_detach(&hctx->entropy);
+ if (hctx->rndvector != NULL)
+ isc_mem_put(mctx, hctx->rndvector, hctx->vectorlen);
+
+ UNLOCK(&hctx->lock);
+
+ DESTROYLOCK(&hctx->lock);
+
+ memset(hctx, 0, sizeof(isc_hash_t));
+ 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(void) {
+ unsigned int refs;
+
+ INSIST(isc_hashctx != NULL && VALID_HASH(isc_hashctx));
+
+ isc_refcount_decrement(&isc_hashctx->refcnt, &refs);
+ INSIST(refs == 0);
+
+ destroy(&isc_hashctx);
+}
+
+static inline unsigned int
+hash_calc(isc_hash_t *hctx, const unsigned char *key, unsigned int keylen,
+ bool 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 == 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, bool 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,
+ bool case_sensitive)
+{
+ INSIST(isc_hashctx != NULL && VALID_HASH(isc_hashctx));
+ REQUIRE(keylen <= isc_hashctx->limit);
+
+ return (hash_calc(isc_hashctx, key, keylen, case_sensitive));
+}
+
+void
+isc__hash_setvec(const uint16_t *vec) {
+ int i;
+ hash_random_t *p;
+
+ if (isc_hashctx == NULL)
+ return;
+
+ p = isc_hashctx->rndvector;
+ for (i = 0; i < 256; i++) {
+ p[i] = vec[i];
+ }
+}
+
+static uint32_t fnv_offset_basis;
+static isc_once_t fnv_once = ISC_ONCE_INIT;
+static bool fnv_initialized = false;
+
+static void
+fnv_initialize(void) {
+ /*
+ * This function should not leave fnv_offset_basis set to
+ * 0. Also, after this function has been called, if it is called
+ * again, it should not change fnv_offset_basis.
+ */
+ while (fnv_offset_basis == 0) {
+ isc_random_get(&fnv_offset_basis);
+ }
+
+ fnv_initialized = true;
+}
+
+const void *
+isc_hash_get_initializer(void) {
+ if (ISC_UNLIKELY(!fnv_initialized))
+ RUNTIME_CHECK(isc_once_do(&fnv_once, fnv_initialize) == ISC_R_SUCCESS);
+
+ return (&fnv_offset_basis);
+}
+
+void
+isc_hash_set_initializer(const void *initializer) {
+ REQUIRE(initializer != NULL);
+
+ /*
+ * Ensure that fnv_initialize() is not called after
+ * isc_hash_set_initializer() is called.
+ */
+ if (ISC_UNLIKELY(!fnv_initialized))
+ RUNTIME_CHECK(isc_once_do(&fnv_once, fnv_initialize) == ISC_R_SUCCESS);
+
+ fnv_offset_basis = *((const unsigned int *) initializer);
+}
+
+uint32_t
+isc_hash_function(const void *data, size_t length,
+ bool case_sensitive,
+ const uint32_t *previous_hashp)
+{
+ uint32_t hval;
+ const unsigned char *bp;
+ const unsigned char *be;
+
+ REQUIRE(length == 0 || data != NULL);
+
+ if (ISC_UNLIKELY(!fnv_initialized))
+ RUNTIME_CHECK(isc_once_do(&fnv_once, fnv_initialize) == ISC_R_SUCCESS);
+
+ hval = ISC_UNLIKELY(previous_hashp != NULL) ?
+ *previous_hashp : fnv_offset_basis;
+
+ if (length == 0)
+ return (hval);
+
+ bp = (const unsigned char *) data;
+ be = bp + length;
+
+ /*
+ * Fowler-Noll-Vo FNV-1a hash function.
+ *
+ * NOTE: A random FNV offset basis is used by default to avoid
+ * collision attacks as the hash function is reversible. This
+ * makes the mapping non-deterministic, but the distribution in
+ * the domain is still uniform.
+ */
+
+ if (case_sensitive) {
+ while (bp <= be - 4) {
+ hval ^= bp[0];
+ hval *= 16777619;
+ hval ^= bp[1];
+ hval *= 16777619;
+ hval ^= bp[2];
+ hval *= 16777619;
+ hval ^= bp[3];
+ hval *= 16777619;
+ bp += 4;
+ }
+ while (bp < be) {
+ hval ^= *bp++;
+ hval *= 16777619;
+ }
+ } else {
+ while (bp <= be - 4) {
+ hval ^= maptolower[bp[0]];
+ hval *= 16777619;
+ hval ^= maptolower[bp[1]];
+ hval *= 16777619;
+ hval ^= maptolower[bp[2]];
+ hval *= 16777619;
+ hval ^= maptolower[bp[3]];
+ hval *= 16777619;
+ bp += 4;
+ }
+ while (bp < be) {
+ hval ^= maptolower[*bp++];
+ hval *= 16777619;
+ }
+ }
+
+ return (hval);
+}
+
+uint32_t
+isc_hash_function_reverse(const void *data, size_t length,
+ bool case_sensitive,
+ const uint32_t *previous_hashp)
+{
+ uint32_t hval;
+ const unsigned char *bp;
+ const unsigned char *be;
+
+ REQUIRE(length == 0 || data != NULL);
+
+ if (ISC_UNLIKELY(!fnv_initialized))
+ RUNTIME_CHECK(isc_once_do(&fnv_once, fnv_initialize) == ISC_R_SUCCESS);
+
+ hval = ISC_UNLIKELY(previous_hashp != NULL) ?
+ *previous_hashp : fnv_offset_basis;
+
+ if (length == 0)
+ return (hval);
+
+ bp = (const unsigned char *) data;
+ be = bp + length;
+
+ /*
+ * Fowler-Noll-Vo FNV-1a hash function.
+ *
+ * NOTE: A random FNV offset basis is used by default to avoid
+ * collision attacks as the hash function is reversible. This
+ * makes the mapping non-deterministic, but the distribution in
+ * the domain is still uniform.
+ */
+
+ if (case_sensitive) {
+ while (be >= bp + 4) {
+ be -= 4;
+ hval ^= be[3];
+ hval *= 16777619;
+ hval ^= be[2];
+ hval *= 16777619;
+ hval ^= be[1];
+ hval *= 16777619;
+ hval ^= be[0];
+ hval *= 16777619;
+ }
+ while (--be >= bp) {
+ hval ^= *be;
+ hval *= 16777619;
+ }
+ } else {
+ while (be >= bp + 4) {
+ be -= 4;
+ hval ^= maptolower[be[3]];
+ hval *= 16777619;
+ hval ^= maptolower[be[2]];
+ hval *= 16777619;
+ hval ^= maptolower[be[1]];
+ hval *= 16777619;
+ hval ^= maptolower[be[0]];
+ hval *= 16777619;
+ }
+ while (--be >= bp) {
+ hval ^= maptolower[*be];
+ hval *= 16777619;
+ }
+ }
+
+ return (hval);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2025-01-08 04:55:34 +0000