hash.c revision 1.4 
1/*	$NetBSD: hash.c,v 1.4 2019/09/05 19:32:59 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 <config.h> // IWYU pragma: keep
19
20#include <stdbool.h>
21#include <stddef.h>
22#include <inttypes.h>
23#if defined(WIN32) || defined(WIN64)
24#include <malloc.h>
25#endif
26
27#include "isc/hash.h" // IWYU pragma: keep
28#include "isc/likely.h"
29#include "isc/once.h"
30#include "isc/random.h"
31#include "isc/result.h"
32#include "isc/types.h"
33#include "isc/util.h"
34#include "isc/siphash.h"
35#include "isc/string.h"
36
37#include "entropy_private.h"
38
39static uint8_t isc_hash_key[16];
40static bool hash_initialized = false;
41static isc_once_t isc_hash_once = ISC_ONCE_INIT;
42
43static void
44isc_hash_initialize(void) {
45	uint64_t key[2] = { 0, 1 };
46#if FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
47	/*
48	 * Set a constant key to help in problem reproduction should
49	 * fuzzing find a crash or a hang.
50	 */
51#else
52	isc_entropy_get(key, sizeof(key));
53#endif
54	memmove(isc_hash_key, key, sizeof(isc_hash_key));
55	hash_initialized = true;
56}
57
58static uint8_t maptolower[] = {
59	0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
60	0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
61	0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
62	0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
63	0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
64	0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
65	0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
66	0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
67	0x40, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67,
68	0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f,
69	0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77,
70	0x78, 0x79, 0x7a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f,
71	0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67,
72	0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f,
73	0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77,
74	0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f,
75	0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
76	0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
77	0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97,
78	0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f,
79	0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
80	0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf,
81	0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7,
82	0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf,
83	0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,
84	0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf,
85	0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7,
86	0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf,
87	0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7,
88	0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef,
89	0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
90	0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff
91};
92
93const void *
94isc_hash_get_initializer(void) {
95	if (ISC_UNLIKELY(!hash_initialized)) {
96		RUNTIME_CHECK(isc_once_do(&isc_hash_once,
97					  isc_hash_initialize)
98			      == ISC_R_SUCCESS);
99	}
100
101	return (isc_hash_key);
102}
103
104void
105isc_hash_set_initializer(const void *initializer) {
106	REQUIRE(initializer != NULL);
107
108	/*
109	 * Ensure that isc_hash_initialize() is not called after
110	 * isc_hash_set_initializer() is called.
111	 */
112	if (ISC_UNLIKELY(!hash_initialized)) {
113		RUNTIME_CHECK(isc_once_do(&isc_hash_once,
114					  isc_hash_initialize)
115			      == ISC_R_SUCCESS);
116	}
117
118	memmove(isc_hash_key, initializer, sizeof(isc_hash_key));
119}
120
121uint64_t
122isc_hash_function(const void *data,
123		  const size_t length,
124		  const bool case_sensitive)
125{
126	uint64_t hval;
127
128	REQUIRE(length == 0 || data != NULL);
129
130	RUNTIME_CHECK(isc_once_do(&isc_hash_once,
131				  isc_hash_initialize) == ISC_R_SUCCESS);
132
133	if (case_sensitive) {
134		isc_siphash24(isc_hash_key, data, length, (uint8_t *)&hval);
135	} else {
136		uint8_t input[1024];
137		REQUIRE(length <= 1024);
138		for (unsigned int i = 0; i < length; i++) {
139			input[i] = maptolower[((const uint8_t *)data)[i]];
140		}
141		isc_siphash24(isc_hash_key, input, length, (uint8_t *)&hval);
142	}
143
144	return (hval);
145}
146