308 lines
9 KiB
C++
308 lines
9 KiB
C++
// Copyright (c) 2018-2019 The Bitcoin Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#include <mutex>
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#include <sstream>
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#include <set>
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#include <blockfilter.h>
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#include <crypto/siphash.h>
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#include <hash.h>
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#include <primitives/transaction.h>
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#include <script/script.h>
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#include <streams.h>
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#include <util/golombrice.h>
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/// SerType used to serialize parameters in GCS filter encoding.
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static constexpr int GCS_SER_TYPE = SER_NETWORK;
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/// Protocol version used to serialize parameters in GCS filter encoding.
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static constexpr int GCS_SER_VERSION = 0;
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static const std::map<BlockFilterType, std::string> g_filter_types = {
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{BlockFilterType::BASIC, "basic"},
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};
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// Map a value x that is uniformly distributed in the range [0, 2^64) to a
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// value uniformly distributed in [0, n) by returning the upper 64 bits of
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// x * n.
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//
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// See: https://lemire.me/blog/2016/06/27/a-fast-alternative-to-the-modulo-reduction/
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static uint64_t MapIntoRange(uint64_t x, uint64_t n)
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{
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#ifdef __SIZEOF_INT128__
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return (static_cast<unsigned __int128>(x) * static_cast<unsigned __int128>(n)) >> 64;
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#else
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// To perform the calculation on 64-bit numbers without losing the
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// result to overflow, split the numbers into the most significant and
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// least significant 32 bits and perform multiplication piece-wise.
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//
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// See: https://stackoverflow.com/a/26855440
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uint64_t x_hi = x >> 32;
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uint64_t x_lo = x & 0xFFFFFFFF;
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uint64_t n_hi = n >> 32;
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uint64_t n_lo = n & 0xFFFFFFFF;
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uint64_t ac = x_hi * n_hi;
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uint64_t ad = x_hi * n_lo;
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uint64_t bc = x_lo * n_hi;
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uint64_t bd = x_lo * n_lo;
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uint64_t mid34 = (bd >> 32) + (bc & 0xFFFFFFFF) + (ad & 0xFFFFFFFF);
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uint64_t upper64 = ac + (bc >> 32) + (ad >> 32) + (mid34 >> 32);
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return upper64;
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#endif
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}
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uint64_t GCSFilter::HashToRange(const Element& element) const
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{
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uint64_t hash = CSipHasher(m_params.m_siphash_k0, m_params.m_siphash_k1)
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.Write(element.data(), element.size())
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.Finalize();
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return MapIntoRange(hash, m_F);
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}
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std::vector<uint64_t> GCSFilter::BuildHashedSet(const ElementSet& elements) const
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{
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std::vector<uint64_t> hashed_elements;
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hashed_elements.reserve(elements.size());
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for (const Element& element : elements) {
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hashed_elements.push_back(HashToRange(element));
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}
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std::sort(hashed_elements.begin(), hashed_elements.end());
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return hashed_elements;
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}
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GCSFilter::GCSFilter(const Params& params)
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: m_params(params), m_N(0), m_F(0), m_encoded{0}
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{}
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GCSFilter::GCSFilter(const Params& params, std::vector<unsigned char> encoded_filter)
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: m_params(params), m_encoded(std::move(encoded_filter))
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{
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VectorReader stream(GCS_SER_TYPE, GCS_SER_VERSION, m_encoded, 0);
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uint64_t N = ReadCompactSize(stream);
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m_N = static_cast<uint32_t>(N);
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if (m_N != N) {
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throw std::ios_base::failure("N must be <2^32");
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}
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m_F = static_cast<uint64_t>(m_N) * static_cast<uint64_t>(m_params.m_M);
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// Verify that the encoded filter contains exactly N elements. If it has too much or too little
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// data, a std::ios_base::failure exception will be raised.
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BitStreamReader<VectorReader> bitreader(stream);
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for (uint64_t i = 0; i < m_N; ++i) {
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GolombRiceDecode(bitreader, m_params.m_P);
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}
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if (!stream.empty()) {
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throw std::ios_base::failure("encoded_filter contains excess data");
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}
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}
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GCSFilter::GCSFilter(const Params& params, const ElementSet& elements)
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: m_params(params)
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{
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size_t N = elements.size();
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m_N = static_cast<uint32_t>(N);
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if (m_N != N) {
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throw std::invalid_argument("N must be <2^32");
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}
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m_F = static_cast<uint64_t>(m_N) * static_cast<uint64_t>(m_params.m_M);
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CVectorWriter stream(GCS_SER_TYPE, GCS_SER_VERSION, m_encoded, 0);
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WriteCompactSize(stream, m_N);
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if (elements.empty()) {
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return;
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}
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BitStreamWriter<CVectorWriter> bitwriter(stream);
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uint64_t last_value = 0;
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for (uint64_t value : BuildHashedSet(elements)) {
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uint64_t delta = value - last_value;
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GolombRiceEncode(bitwriter, m_params.m_P, delta);
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last_value = value;
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}
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bitwriter.Flush();
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}
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bool GCSFilter::MatchInternal(const uint64_t* element_hashes, size_t size) const
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{
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VectorReader stream(GCS_SER_TYPE, GCS_SER_VERSION, m_encoded, 0);
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// Seek forward by size of N
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uint64_t N = ReadCompactSize(stream);
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assert(N == m_N);
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BitStreamReader<VectorReader> bitreader(stream);
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uint64_t value = 0;
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size_t hashes_index = 0;
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for (uint32_t i = 0; i < m_N; ++i) {
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uint64_t delta = GolombRiceDecode(bitreader, m_params.m_P);
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value += delta;
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while (true) {
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if (hashes_index == size) {
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return false;
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} else if (element_hashes[hashes_index] == value) {
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return true;
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} else if (element_hashes[hashes_index] > value) {
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break;
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}
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hashes_index++;
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}
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}
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return false;
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}
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bool GCSFilter::Match(const Element& element) const
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{
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uint64_t query = HashToRange(element);
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return MatchInternal(&query, 1);
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}
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bool GCSFilter::MatchAny(const ElementSet& elements) const
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{
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const std::vector<uint64_t> queries = BuildHashedSet(elements);
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return MatchInternal(queries.data(), queries.size());
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}
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const std::string& BlockFilterTypeName(BlockFilterType filter_type)
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{
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static std::string unknown_retval = "";
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auto it = g_filter_types.find(filter_type);
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return it != g_filter_types.end() ? it->second : unknown_retval;
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}
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bool BlockFilterTypeByName(const std::string& name, BlockFilterType& filter_type) {
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for (const auto& entry : g_filter_types) {
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if (entry.second == name) {
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filter_type = entry.first;
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return true;
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}
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}
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return false;
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}
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const std::set<BlockFilterType>& AllBlockFilterTypes()
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{
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static std::set<BlockFilterType> types;
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static std::once_flag flag;
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std::call_once(flag, []() {
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for (auto entry : g_filter_types) {
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types.insert(entry.first);
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}
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});
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return types;
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}
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const std::string& ListBlockFilterTypes()
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{
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static std::string type_list;
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static std::once_flag flag;
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std::call_once(flag, []() {
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std::stringstream ret;
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bool first = true;
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for (auto entry : g_filter_types) {
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if (!first) ret << ", ";
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ret << entry.second;
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first = false;
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}
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type_list = ret.str();
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});
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return type_list;
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}
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static GCSFilter::ElementSet BasicFilterElements(const CBlock& block,
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const CBlockUndo& block_undo)
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{
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GCSFilter::ElementSet elements;
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for (const CTransactionRef& tx : block.vtx) {
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for (const CTxOut& txout : tx->vout) {
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const CScript& script = txout.scriptPubKey;
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if (script.empty() || script[0] == OP_RETURN) continue;
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elements.emplace(script.begin(), script.end());
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}
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}
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for (const CTxUndo& tx_undo : block_undo.vtxundo) {
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for (const Coin& prevout : tx_undo.vprevout) {
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const CScript& script = prevout.out.scriptPubKey;
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if (script.empty()) continue;
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elements.emplace(script.begin(), script.end());
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}
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}
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return elements;
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}
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BlockFilter::BlockFilter(BlockFilterType filter_type, const uint256& block_hash,
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std::vector<unsigned char> filter)
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: m_filter_type(filter_type), m_block_hash(block_hash)
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{
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GCSFilter::Params params;
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if (!BuildParams(params)) {
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throw std::invalid_argument("unknown filter_type");
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}
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m_filter = GCSFilter(params, std::move(filter));
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}
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BlockFilter::BlockFilter(BlockFilterType filter_type, const CBlock& block, const CBlockUndo& block_undo)
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: m_filter_type(filter_type), m_block_hash(block.GetHash())
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{
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GCSFilter::Params params;
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if (!BuildParams(params)) {
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throw std::invalid_argument("unknown filter_type");
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}
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m_filter = GCSFilter(params, BasicFilterElements(block, block_undo));
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}
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bool BlockFilter::BuildParams(GCSFilter::Params& params) const
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{
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switch (m_filter_type) {
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case BlockFilterType::BASIC:
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params.m_siphash_k0 = m_block_hash.GetUint64(0);
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params.m_siphash_k1 = m_block_hash.GetUint64(1);
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params.m_P = BASIC_FILTER_P;
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params.m_M = BASIC_FILTER_M;
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return true;
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case BlockFilterType::INVALID:
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return false;
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}
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return false;
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}
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uint256 BlockFilter::GetHash() const
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{
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const std::vector<unsigned char>& data = GetEncodedFilter();
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uint256 result;
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CHash256().Write(data.data(), data.size()).Finalize(result.begin());
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return result;
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}
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uint256 BlockFilter::ComputeHeader(const uint256& prev_header) const
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{
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const uint256& filter_hash = GetHash();
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uint256 result;
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CHash256()
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.Write(filter_hash.begin(), filter_hash.size())
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.Write(prev_header.begin(), prev_header.size())
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.Finalize(result.begin());
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return result;
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}
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