--- /dev/null
+/*
+ * Copyright (C) 2003 Internet Software Consortium.
+ *
+ * Permission to use, copy, modify, and 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 INTERNET SOFTWARE CONSORTIUM
+ * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
+ * INTERNET SOFTWARE CONSORTIUM 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 1.2 2003/07/25 02:22:26 marka Exp $ */
+
+/*
+ * Some portion of this code was derived from universal hash function
+ * libraries of Rice University.
+ */
+
+/* "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 <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/rwlock.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;
+
+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_rwlock_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 ret;
+ 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) {
+ ret = ISC_R_NOMEMORY;
+ goto errout;
+ }
+
+ /*
+ * We need a lock.
+ */
+ if (isc_mutex_init(&hctx->lock) != ISC_R_SUCCESS) {
+ ret = ISC_R_UNEXPECTED;
+ 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;
+ isc_refcount_init(&hctx->refcnt, 1);
+ 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);
+
+ errout:
+ isc_mem_put(mctx, hctx, sizeof(isc_hash_t));
+ if (rv != NULL)
+ isc_mem_put(mctx, rv, vlen);
+
+ return (ret);
+}
+
+static void
+initialize_lock(void) {
+ RUNTIME_CHECK(isc_rwlock_init(&createlock, 0, 0) == 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);
+
+ RWLOCK(&createlock, isc_rwlocktype_write);
+
+ if (hash == NULL)
+ result = isc_hash_ctxcreate(mctx, entropy, limit, &hash);
+
+ RWUNLOCK(&createlock, isc_rwlocktype_write);
+
+ return (result);
+}
+
+void
+isc_hash_ctxinit(isc_hash_t *hctx) {
+ isc_result_t result;
+
+ LOCK(&hctx->lock);
+
+ if (hctx->initialized == ISC_TRUE)
+ goto out;
+
+ if (hctx->entropy) {
+ result = isc_entropy_getdata(hctx->entropy,
+ hctx->rndvector, hctx->vectorlen,
+ NULL, 0);
+ INSIST(result == ISC_R_SUCCESS);
+ } else {
+ isc_int32_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;
+
+ 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() {
+ 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));
+}
--- /dev/null
+/*
+ * Copyright (C) 2003 Internet Software Consortium.
+ *
+ * Permission to use, copy, modify, and 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 INTERNET SOFTWARE CONSORTIUM
+ * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
+ * INTERNET SOFTWARE CONSORTIUM 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.h,v 1.2 2003/07/25 02:22:26 marka Exp $ */
+
+#ifndef ISC_HASH_H
+#define ISC_HASH_H 1
+
+/*****
+ ***** Module Info
+ *****/
+
+/*
+ * Hash
+ *
+ * The hash API
+ *
+ * Provides an unpredictable hash value for variable length data.
+ * A hash object contains a random vector (which is hidden from clients
+ * of this API) to make the actual hash value unpredictable.
+ *
+ * The algorithm used in the API guarantees the probability of hash
+ * collision; in the current implementation, as long as the values stored
+ * in the random vector are unpredictable, the probability of hash
+ * collision between arbitrary two different values is at most 1/2^16.
+ *
+ * Altough the API is generic about the hash keys, it mainly expects
+ * DNS names (and sometimes IPv4/v6 addresses) as inputs. It has an
+ * upper limit of the input length, and may run slow to calculaate the
+ * has values for large inputs.
+ *
+ * This API is designed to be general so that it can provide multiple
+ * different hash contexts that have different random vectors. However,
+ * it should be typical to have a single context for an entire system.
+ * To support such cases, the API also provides a single-context mode.
+ *
+ * MP:
+ * The hash object is almost read-only. Once the internal random vector
+ * is initialized, no write operation will occur, and there will be no
+ * need to lock the object to calculate actual hash values.
+ *
+ * Reliability:
+ * In some cases this module uses low-level data copy to initialize the
+ * random vector. Errors in this part are likely to crash the server or
+ * corrupt memory.
+ *
+ * Resources:
+ * A buffer, used as a random vector for calculating hash values.
+ *
+ * Security:
+ * This module intends to provide unpredictable hash values in
+ * adversarial environments in order to avoid denial of service attacks
+ * to hash buckets.
+ * Its unpredictability relies on the quality of entropy to build the
+ * random vector.
+ *
+ * Standards:
+ * None.
+ */
+
+/***
+ *** Imports
+ ***/
+
+#include <isc/types.h>
+
+/***
+ *** Functions
+ ***/
+ISC_LANG_BEGINDECLS
+
+isc_result_t
+isc_hash_ctxcreate(isc_mem_t *mctx, isc_entropy_t *entropy, unsigned int limit,
+ isc_hash_t **hctx);
+isc_result_t
+isc_hash_create(isc_mem_t *mctx, isc_entropy_t *entropy, size_t limit);
+/*
+ * Create a new hash object.
+ *
+ * isc_hash_ctxcreate() creates a different object.
+ * isc_hash_create() creates a module-internal object to support the
+ * single-context mode. It should be called only once.
+ *
+ * 'entropy' must be NULL or a valid entropy object. If 'entropy' is NULL,
+ * pseudo random values will be used to build the random vector, which may
+ * weaken security.
+ *
+ * 'limit' specifies the maximum number of hash keys. If it is too large,
+ * these functions may fail.
+ */
+
+void
+isc_hash_ctxattach(isc_hash_t *hctx, isc_hash_t **hctxp);
+/*
+ * Attach to a hash object.
+ * This function is only necessary for the multiple-context mode.
+ */
+
+void
+isc_hash_ctxdetach(isc_hash_t **hctxp);
+/*
+ * Detach from a hash object.
+ *
+ * This function is for the multiple-context mode, and takes a valid
+ * hash object as an argument.
+ */
+
+void
+isc_hash_destroy(void);
+/*
+ * This function is for the single-context mode, and is expected to be used
+ * as a counterpart of isc_hash_create().
+ * A valid module-internal hash object must have been created, and this
+ * function should be called only once.
+ */
+
+void
+isc_hash_ctxinit(isc_hash_t *hctx);
+void
+isc_hash_init(void);
+/*
+ * Initialize a hash object. It fills in the random vector with a proper
+ * source of entropy, which is typically from the entropy object specified
+ * at the creation. Thus, it is desirable to call these functions after
+ * initializing the entropy object with some good entropy sources.
+ *
+ * These functions should be called before the first hash calculation.
+ *
+ * isc_hash_ctxinit() is for the multiple-context mode, and takes a valid hash
+ * object as an argument.
+ * isc_hash_init() is for the single-context mode. A valid module-internal
+ * hash object must have been created, and this function should be called only
+ * once.
+ */
+
+unsigned int
+isc_hash_ctxcalc(isc_hash_t *hctx, const unsigned char *key,
+ unsigned int keylen, isc_boolean_t case_sensitive);
+unsigned int
+isc_hash_calc(const unsigned char *key, unsigned int keylen,
+ isc_boolean_t case_sensitive);
+/*
+ * Calculate a hash value.
+ *
+ * isc_hash_ctxinit() is for the multiple-context mode, and takes a valid hash
+ * object as an argument.
+ * isc_hash_init() is for the single-context mode. A valid module-internal
+ * hash object must have been created.
+ *
+ * 'key' is the hash key, which is a variable length buffer.
+ * 'keylen' specifies the key length, which must not be larger than the limit
+ * specified for the corresponding hash object.
+ *
+ * 'case_sensitive' specifies whether the hash key should be treated as
+ * case_sensitive values. It should typically be ISC_FALSE if the hash key
+ * is a DNS name.
+ */
+
+ISC_LANG_ENDDECLS
+
+#endif /* ISC_HASH_H */
projects / thirdparty / bind9.git / commitdiff
