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78 lines
1.5 KiB
C++
78 lines
1.5 KiB
C++
/*
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* Copyright (c) 2013-2020, The PurpleI2P Project
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*
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* This file is part of Purple i2pd project and licensed under BSD3
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*
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* See full license text in LICENSE file at top of project tree
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*/
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#include "BloomFilter.h"
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#include "I2PEndian.h"
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#include <array>
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#include <openssl/sha.h>
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namespace i2p
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{
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namespace util
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{
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/** @brief decaying bloom filter implementation */
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class DecayingBloomFilter : public IBloomFilter
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{
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public:
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DecayingBloomFilter(const std::size_t size)
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{
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m_Size = size;
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m_Data = new uint8_t[size];
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}
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/** @brief implements IBloomFilter::~IBloomFilter */
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~DecayingBloomFilter()
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{
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delete [] m_Data;
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}
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/** @brief implements IBloomFilter::Add */
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bool Add(const uint8_t * data, std::size_t len)
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{
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std::size_t idx;
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uint8_t mask;
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Get(data, len, idx, mask);
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if(m_Data[idx] & mask) return false; // filter hit
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m_Data[idx] |= mask;
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return true;
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}
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/** @brief implements IBloomFilter::Decay */
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void Decay()
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{
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// reset bloom filter buffer
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memset(m_Data, 0, m_Size);
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}
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private:
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/** @brief get bit index for for data */
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void Get(const uint8_t * data, std::size_t len, std::size_t & idx, uint8_t & bm)
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{
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bm = 1;
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uint8_t digest[32];
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// TODO: use blake2 because it's faster
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SHA256(data, len, digest);
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uint64_t i = buf64toh(digest);
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idx = i % m_Size;
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bm <<= (i % 8);
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}
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uint8_t * m_Data;
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std::size_t m_Size;
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};
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BloomFilterPtr BloomFilter(std::size_t capacity)
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{
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return std::make_shared<DecayingBloomFilter>(capacity);
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}
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}
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}
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