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hash.c revision 1.5 
      1 /*	$NetBSD: hash.c,v 1.5 2020/05/24 19:46:26 christos Exp $	*/
      2 
      3 /*
      4  * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
      5  *
      6  * This Source Code Form is subject to the terms of the Mozilla Public
      7  * License, v. 2.0. If a copy of the MPL was not distributed with this
      8  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
      9  *
     10  * See the COPYRIGHT file distributed with this work for additional
     11  * information regarding copyright ownership.
     12  */
     13 
     14 /*
     15  * 32 bit Fowler/Noll/Vo FNV-1a hash code with modification for BIND
     16  */
     17 
     18 #include <inttypes.h>
     19 #include <stdbool.h>
     20 #include <stddef.h>
     21 #if defined(WIN32) || defined(WIN64)
     22 #include <malloc.h>
     23 #endif /* if defined(WIN32) || defined(WIN64) */
     24 
     25 #include "entropy_private.h"
     26 #include "isc/hash.h" /* IWYU pragma: keep */
     27 #include "isc/likely.h"
     28 #include "isc/once.h"
     29 #include "isc/random.h"
     30 #include "isc/result.h"
     31 #include "isc/siphash.h"
     32 #include "isc/string.h"
     33 #include "isc/types.h"
     34 #include "isc/util.h"
     35 
     36 static uint8_t isc_hash_key[16];
     37 static bool hash_initialized = false;
     38 static isc_once_t isc_hash_once = ISC_ONCE_INIT;
     39 
     40 static void
     41 isc_hash_initialize(void) {
     42 	uint64_t key[2] = { 0, 1 };
     43 #if FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
     44 	/*
     45 	 * Set a constant key to help in problem reproduction should
     46 	 * fuzzing find a crash or a hang.
     47 	 */
     48 #else  /* if FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION */
     49 	isc_entropy_get(key, sizeof(key));
     50 #endif /* if FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION */
     51 	memmove(isc_hash_key, key, sizeof(isc_hash_key));
     52 	hash_initialized = true;
     53 }
     54 
     55 static uint8_t maptolower[] = {
     56 	0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b,
     57 	0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
     58 	0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0x20, 0x21, 0x22, 0x23,
     59 	0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
     60 	0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b,
     61 	0x3c, 0x3d, 0x3e, 0x3f, 0x40, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67,
     62 	0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, 0x70, 0x71, 0x72, 0x73,
     63 	0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f,
     64 	0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b,
     65 	0x6c, 0x6d, 0x6e, 0x6f, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77,
     66 	0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, 0x80, 0x81, 0x82, 0x83,
     67 	0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
     68 	0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9a, 0x9b,
     69 	0x9c, 0x9d, 0x9e, 0x9f, 0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
     70 	0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf, 0xb0, 0xb1, 0xb2, 0xb3,
     71 	0xb4, 0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf,
     72 	0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xcb,
     73 	0xcc, 0xcd, 0xce, 0xcf, 0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7,
     74 	0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf, 0xe0, 0xe1, 0xe2, 0xe3,
     75 	0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef,
     76 	0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8, 0xf9, 0xfa, 0xfb,
     77 	0xfc, 0xfd, 0xfe, 0xff
     78 };
     79 
     80 const void *
     81 isc_hash_get_initializer(void) {
     82 	if (ISC_UNLIKELY(!hash_initialized)) {
     83 		RUNTIME_CHECK(
     84 			isc_once_do(&isc_hash_once, isc_hash_initialize) ==
     85 			ISC_R_SUCCESS);
     86 	}
     87 
     88 	return (isc_hash_key);
     89 }
     90 
     91 void
     92 isc_hash_set_initializer(const void *initializer) {
     93 	REQUIRE(initializer != NULL);
     94 
     95 	/*
     96 	 * Ensure that isc_hash_initialize() is not called after
     97 	 * isc_hash_set_initializer() is called.
     98 	 */
     99 	if (ISC_UNLIKELY(!hash_initialized)) {
    100 		RUNTIME_CHECK(
    101 			isc_once_do(&isc_hash_once, isc_hash_initialize) ==
    102 			ISC_R_SUCCESS);
    103 	}
    104 
    105 	memmove(isc_hash_key, initializer, sizeof(isc_hash_key));
    106 }
    107 
    108 uint64_t
    109 isc_hash_function(const void *data, const size_t length,
    110 		  const bool case_sensitive) {
    111 	uint64_t hval;
    112 
    113 	REQUIRE(length == 0 || data != NULL);
    114 
    115 	RUNTIME_CHECK(isc_once_do(&isc_hash_once, isc_hash_initialize) ==
    116 		      ISC_R_SUCCESS);
    117 
    118 	if (case_sensitive) {
    119 		isc_siphash24(isc_hash_key, data, length, (uint8_t *)&hval);
    120 	} else {
    121 		uint8_t input[1024];
    122 		REQUIRE(length <= 1024);
    123 		for (unsigned int i = 0; i < length; i++) {
    124 			input[i] = maptolower[((const uint8_t *)data)[i]];
    125 		}
    126 		isc_siphash24(isc_hash_key, input, length, (uint8_t *)&hval);
    127 	}
    128 
    129 	return (hval);
    130 }
    131