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