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59 lines
1.9 KiB
C
59 lines
1.9 KiB
C
/* Copyright (c) 2003-2004, Roger Dingledine
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* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
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* Copyright (c) 2007-2018, The Tor Project, Inc. */
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/* See LICENSE for licensing information */
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#ifndef TOR_BLOOMFILT_H
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#define TOR_BLOOMFILT_H
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#include "orconfig.h"
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#include "lib/cc/torint.h"
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#include "lib/container/bitarray.h"
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#include "siphash.h"
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/** A set of digests, implemented as a Bloom filter. */
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typedef struct {
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int mask; /**< One less than the number of bits in <b>ba</b>; always one less
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* than a power of two. */
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bitarray_t *ba; /**< A bit array to implement the Bloom filter. */
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} digestset_t;
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#define BIT(n) ((n) & set->mask)
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/** Add the digest <b>digest</b> to <b>set</b>. */
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static inline void
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digestset_add(digestset_t *set, const char *digest)
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{
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const uint64_t x = siphash24g(digest, 20);
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const uint32_t d1 = (uint32_t) x;
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const uint32_t d2 = (uint32_t)( (x>>16) + x);
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const uint32_t d3 = (uint32_t)( (x>>32) + x);
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const uint32_t d4 = (uint32_t)( (x>>48) + x);
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bitarray_set(set->ba, BIT(d1));
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bitarray_set(set->ba, BIT(d2));
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bitarray_set(set->ba, BIT(d3));
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bitarray_set(set->ba, BIT(d4));
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}
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/** If <b>digest</b> is in <b>set</b>, return nonzero. Otherwise,
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* <em>probably</em> return zero. */
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static inline int
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digestset_contains(const digestset_t *set, const char *digest)
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{
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const uint64_t x = siphash24g(digest, 20);
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const uint32_t d1 = (uint32_t) x;
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const uint32_t d2 = (uint32_t)( (x>>16) + x);
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const uint32_t d3 = (uint32_t)( (x>>32) + x);
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const uint32_t d4 = (uint32_t)( (x>>48) + x);
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return bitarray_is_set(set->ba, BIT(d1)) &&
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bitarray_is_set(set->ba, BIT(d2)) &&
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bitarray_is_set(set->ba, BIT(d3)) &&
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bitarray_is_set(set->ba, BIT(d4));
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}
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#undef BIT
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digestset_t *digestset_new(int max_elements);
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void digestset_free_(digestset_t* set);
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#define digestset_free(set) FREE_AND_NULL(digestset_t, digestset_free_, (set))
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#endif /* !defined(TOR_CONTAINER_H) */
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