1/*
2 * Copyright (c) 2021 Apple Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
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27 */
28
29#ifndef _NET_BLOOM_FILTER_H_
30#define _NET_BLOOM_FILTER_H_
31
32#include <sys/types.h>
33
34#ifdef __cplusplus
35extern "C" {
36#endif
37
38// A Bloom Filter is a space-efficient probabilistic data structure
39// that is used to test whether an element is a member of a set. It has a small
40// rate of false positives, but it is guaranteed to have no false negatives.
41//
42// net_bloom_filter is a minimal implementation for use in kernel networking
43// that uses three hash functions: net_flowhash_jhash, net_flowhash_mh3_x64_128,
44// and net_flowhash_mh3_x86_32. This is optimal for a 10% false positive rate.
45// The optimal number of bits should be calculated as:
46// num_bits = ((2.3 * ELEMENT_COUNT) / 0.48)
47
48struct net_bloom_filter {
49 uint32_t b_table_num_bits;
50 uint32_t b_table[0];
51};
52
53struct net_bloom_filter *
54net_bloom_filter_create(uint32_t num_bits);
55
56size_t
57net_bloom_filter_get_size(uint32_t num_bits);
58
59void
60net_bloom_filter_destroy(struct net_bloom_filter *filter);
61
62void
63net_bloom_filter_insert(struct net_bloom_filter *filter,
64 const void *buffer,
65 uint32_t length);
66
67bool
68net_bloom_filter_contains(struct net_bloom_filter *filter,
69 const void *buffer,
70 uint32_t length);
71
72#ifdef __cplusplus
73}
74#endif
75
76#endif /* _NET_BLOOM_FILTER_H_ */
77