mirror of
https://gitlab.isc.org/isc-projects/bind9
synced 2025-09-05 17:15:31 +00:00
21a383a8fd
When converting a string to lower case, the compiler is able to autovectorize nicely, so a nice simple implementation is also very fast, comparable to memcpy(). Comparisons are more difficult for the compiler, so we convert eight bytes at a time using "SIMD within a register" tricks. Experiments indicate it's best to stick to simple loops for shorter strings and the remainder of long strings.
122 lines
3.1 KiB
C
122 lines
3.1 KiB
C
/*
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* Copyright (C) Internet Systems Consortium, Inc. ("ISC")
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*
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* SPDX-License-Identifier: MPL-2.0
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, you can obtain one at https://mozilla.org/MPL/2.0/.
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*
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* See the COPYRIGHT file distributed with this work for additional
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* information regarding copyright ownership.
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*/
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#include <inttypes.h>
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#include <stdbool.h>
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#include <stddef.h>
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#include "entropy_private.h"
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#include "isc/ascii.h"
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#include "isc/hash.h" /* IWYU pragma: keep */
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#include "isc/once.h"
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#include "isc/random.h"
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#include "isc/result.h"
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#include "isc/siphash.h"
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#include "isc/string.h"
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#include "isc/types.h"
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#include "isc/util.h"
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static uint8_t isc_hash_key[16];
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static uint8_t isc_hash32_key[8];
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static bool hash_initialized = false;
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static isc_once_t isc_hash_once = ISC_ONCE_INIT;
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static void
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isc_hash_initialize(void) {
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/*
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* Set a constant key to help in problem reproduction should
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* fuzzing find a crash or a hang.
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*/
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uint64_t key[2] = { 0, 1 };
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#if !FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
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isc_entropy_get(key, sizeof(key));
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#endif /* if FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION */
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memmove(isc_hash_key, key, sizeof(isc_hash_key));
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#if !FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
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isc_entropy_get(key, sizeof(key));
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#endif /* if FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION */
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memmove(isc_hash32_key, key, sizeof(isc_hash32_key));
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hash_initialized = true;
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}
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const void *
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isc_hash_get_initializer(void) {
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if (!hash_initialized) {
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RUNTIME_CHECK(
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isc_once_do(&isc_hash_once, isc_hash_initialize) ==
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ISC_R_SUCCESS);
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}
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return (isc_hash_key);
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}
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void
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isc_hash_set_initializer(const void *initializer) {
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REQUIRE(initializer != NULL);
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/*
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* Ensure that isc_hash_initialize() is not called after
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* isc_hash_set_initializer() is called.
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*/
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if (!hash_initialized) {
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RUNTIME_CHECK(
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isc_once_do(&isc_hash_once, isc_hash_initialize) ==
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ISC_R_SUCCESS);
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}
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memmove(isc_hash_key, initializer, sizeof(isc_hash_key));
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}
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uint64_t
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isc_hash64(const void *data, const size_t length, const bool case_sensitive) {
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uint64_t hval;
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REQUIRE(length == 0 || data != NULL);
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RUNTIME_CHECK(isc_once_do(&isc_hash_once, isc_hash_initialize) ==
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ISC_R_SUCCESS);
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if (case_sensitive) {
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isc_siphash24(isc_hash_key, data, length, (uint8_t *)&hval);
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} else {
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uint8_t lower[1024];
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REQUIRE(length <= sizeof(lower));
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isc_ascii_lowercopy(lower, data, length);
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isc_siphash24(isc_hash_key, lower, length, (uint8_t *)&hval);
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}
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return (hval);
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}
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uint32_t
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isc_hash32(const void *data, const size_t length, const bool case_sensitive) {
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uint32_t hval;
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REQUIRE(length == 0 || data != NULL);
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RUNTIME_CHECK(isc_once_do(&isc_hash_once, isc_hash_initialize) ==
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ISC_R_SUCCESS);
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if (case_sensitive) {
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isc_halfsiphash24(isc_hash_key, data, length, (uint8_t *)&hval);
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} else {
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uint8_t lower[1024];
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REQUIRE(length <= sizeof(lower));
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isc_ascii_lowercopy(lower, data, length);
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isc_halfsiphash24(isc_hash_key, lower, length,
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(uint8_t *)&hval);
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}
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return (hval);
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}
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