git / moonbite-core / src/bloom.h · raw

// Copyright (c) 2012-2019 The Bitcoin Core developers// Distributed under the MIT software license, see the accompanying// file COPYING or http://www.opensource.org/licenses/mit-license.php.#ifndef BITCOIN_BLOOM_H#define BITCOIN_BLOOM_H#include <serialize.h>#include <vector>class COutPoint;class CTransaction;class uint256;//! 20,000 items with fp rate < 0.1% or 10,000 items and <0.0001%static const unsigned int MAX_BLOOM_FILTER_SIZE = 36000; // bytesstatic const unsigned int MAX_HASH_FUNCS = 50;/** * First two bits of nFlags control how much IsRelevantAndUpdate actually updates * The remaining bits are reserved */enum bloomflags{    BLOOM_UPDATE_NONE = 0,    BLOOM_UPDATE_ALL = 1,    // Only adds outpoints to the filter if the output is a pay-to-pubkey/pay-to-multisig script    BLOOM_UPDATE_P2PUBKEY_ONLY = 2,    BLOOM_UPDATE_MASK = 3,};/** * BloomFilter is a probabilistic filter which SPV clients provide * so that we can filter the transactions we send them. * * This allows for significantly more efficient transaction and block downloads. * * Because bloom filters are probabilistic, a SPV node can increase the false- * positive rate, making us send it transactions which aren't actually its, * allowing clients to trade more bandwidth for more privacy by obfuscating which * keys are controlled by them. */class CBloomFilter{private:    std::vector<unsigned char> vData;    unsigned int nHashFuncs;    unsigned int nTweak;    unsigned char nFlags;    unsigned int Hash(unsigned int nHashNum, const std::vector<unsigned char>& vDataToHash) const;public:    /**     * Creates a new bloom filter which will provide the given fp rate when filled with the given number of elements     * Note that if the given parameters will result in a filter outside the bounds of the protocol limits,     * the filter created will be as close to the given parameters as possible within the protocol limits.     * This will apply if nFPRate is very low or nElements is unreasonably high.     * nTweak is a constant which is added to the seed value passed to the hash function     * It should generally always be a random value (and is largely only exposed for unit testing)     * nFlags should be one of the BLOOM_UPDATE_* enums (not _MASK)     */    CBloomFilter(const unsigned int nElements, const double nFPRate, const unsigned int nTweak, unsigned char nFlagsIn);    CBloomFilter() : nHashFuncs(0), nTweak(0), nFlags(0) {}    SERIALIZE_METHODS(CBloomFilter, obj) { READWRITE(obj.vData, obj.nHashFuncs, obj.nTweak, obj.nFlags); }    void insert(const std::vector<unsigned char>& vKey);    void insert(const COutPoint& outpoint);    void insert(const uint256& hash);    bool contains(const std::vector<unsigned char>& vKey) const;    bool contains(const COutPoint& outpoint) const;    bool contains(const uint256& hash) const;    //! True if the size is <= MAX_BLOOM_FILTER_SIZE and the number of hash functions is <= MAX_HASH_FUNCS    //! (catch a filter which was just deserialized which was too big)    bool IsWithinSizeConstraints() const;    //! Also adds any outputs which match the filter to the filter (to match their spending txes)    bool IsRelevantAndUpdate(const CTransaction& tx);};/** * RollingBloomFilter is a probabilistic "keep track of most recently inserted" set. * Construct it with the number of items to keep track of, and a false-positive * rate. Unlike CBloomFilter, by default nTweak is set to a cryptographically * secure random value for you. Similarly rather than clear() the method * reset() is provided, which also changes nTweak to decrease the impact of * false-positives. * * contains(item) will always return true if item was one of the last N to 1.5*N * insert()'ed ... but may also return true for items that were not inserted. * * It needs around 1.8 bytes per element per factor 0.1 of false positive rate. * (More accurately: 3/(log(256)*log(2)) * log(1/fpRate) * nElements bytes) */class CRollingBloomFilter{public:    CRollingBloomFilter(const unsigned int nElements, const double nFPRate);    void insert(const std::vector<unsigned char>& vKey);    void insert(const uint256& hash);    bool contains(const std::vector<unsigned char>& vKey) const;    bool contains(const uint256& hash) const;    void reset();private:    int nEntriesPerGeneration;    int nEntriesThisGeneration;    int nGeneration;    std::vector<uint64_t> data;    unsigned int nTweak;    int nHashFuncs;};#endif // BITCOIN_BLOOM_H