implement simple bloom filter

This commit is contained in:
Jeff Becker 2016-12-09 09:08:03 -05:00
parent 447f5f69c9
commit 79e1d54e4c
4 changed files with 102 additions and 1 deletions

69
BloomFilter.cpp Normal file
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#include "BloomFilter.h"
#include "I2PEndian.h"
#include <array>
#include <openssl/sha.h>
namespace i2p
{
namespace util
{
/** @brief decaying bloom filter implementation */
class DecayingBloomFilter : public IBloomFilter
{
public:
DecayingBloomFilter(const std::size_t size)
{
m_Size = size;
m_Data = new uint8_t[size];
}
/** @brief implements IBloomFilter::~IBloomFilter */
~DecayingBloomFilter()
{
delete [] m_Data;
}
/** @brief implements IBloomFilter::Add */
bool Add(const uint8_t * data, std::size_t len)
{
std::size_t idx;
uint8_t mask;
Get(data, len, idx, mask);
if(m_Data[idx] & mask) return false; // filter hit
m_Data[idx] |= mask;
return true;
}
/** @brief implements IBloomFilter::Decay */
void Decay()
{
// reset bloom filter buffer
memset(m_Data, 0, m_Size);
}
private:
/** @brief get bit index for for data */
void Get(const uint8_t * data, std::size_t len, std::size_t & idx, uint8_t & bm)
{
bm = 1;
uint8_t digest[32];
// TODO: use blake2 because it's faster
SHA256(data, len, digest);
uint64_t i = buf64toh(digest);
idx = i % m_Size;
bm <<= (i % 8);
}
uint8_t * m_Data;
std::size_t m_Size;
};
BloomFilterPtr BloomFilter(std::size_t capacity)
{
return std::make_shared<DecayingBloomFilter>(capacity);
}
}
}

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BloomFilter.h Normal file
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#ifndef BLOOM_FILTER_H_
#define BLOOM_FILTER_H_
#include <memory>
#include <cstdint>
namespace i2p
{
namespace util
{
/** @brief interface for bloom filter */
struct IBloomFilter
{
/** @brief destructor */
virtual ~IBloomFilter();
/** @brief add entry to bloom filter, return false if filter hit otherwise return true */
virtual bool Add(const uint8_t * data, std::size_t len) = 0;
/** @brief optionally decay old entries */
virtual void Decay();
};
typedef std::shared_ptr<IBloomFilter> BloomFilterPtr;
/** @brief create bloom filter */
BloomFilterPtr BloomFilter(std::size_t capacity = 1024 * 8);
}
}
#endif

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@ -26,6 +26,7 @@ set ( CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake_modules" )
set ( CMAKE_SOURCE_DIR ".." )
set (LIBI2PD_SRC
"${CMAKE_SOURCE_DIR}/BloomFilter.cpp"
"${CMAKE_SOURCE_DIR}/Config.cpp"
"${CMAKE_SOURCE_DIR}/Crypto.cpp"
"${CMAKE_SOURCE_DIR}/Garlic.cpp"

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@ -1,5 +1,5 @@
LIB_SRC = \
Gzip.cpp Crypto.cpp Datagram.cpp Garlic.cpp I2NPProtocol.cpp LeaseSet.cpp \
BloomFilter.cpp Gzip.cpp Crypto.cpp Datagram.cpp Garlic.cpp I2NPProtocol.cpp LeaseSet.cpp \
Log.cpp NTCPSession.cpp NetDb.cpp NetDbRequests.cpp Profiling.cpp \
Reseed.cpp RouterContext.cpp RouterInfo.cpp Signature.cpp SSU.cpp \
SSUSession.cpp SSUData.cpp Streaming.cpp Identity.cpp TransitTunnel.cpp \