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blockfilter.cpp
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277 lines (230 loc) · 7.83 KB
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// Copyright (c) 2018-2021 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#include <mutex>
#include <sstream>
#include <set>
#include <blockfilter.h>
#include <crypto/siphash.h>
#include <hash.h>
#include <primitives/transaction.h>
#include <script/script.h>
#include <streams.h>
#include <util/golombrice.h>
/// SerType used to serialize parameters in GCS filter encoding.
static constexpr int GCS_SER_TYPE = SER_NETWORK;
/// Protocol version used to serialize parameters in GCS filter encoding.
static constexpr int GCS_SER_VERSION = 0;
static const std::map<BlockFilterType, std::string> g_filter_types = {
{BlockFilterType::BASIC, "basic"},
};
uint64_t GCSFilter::HashToRange(const Element& element) const
{
uint64_t hash = CSipHasher(m_params.m_siphash_k0, m_params.m_siphash_k1)
.Write(element.data(), element.size())
.Finalize();
return FastRange64(hash, m_F);
}
std::vector<uint64_t> GCSFilter::BuildHashedSet(const ElementSet& elements) const
{
std::vector<uint64_t> hashed_elements;
hashed_elements.reserve(elements.size());
for (const Element& element : elements) {
hashed_elements.push_back(HashToRange(element));
}
std::sort(hashed_elements.begin(), hashed_elements.end());
return hashed_elements;
}
GCSFilter::GCSFilter(const Params& params)
: m_params(params), m_N(0), m_F(0), m_encoded{0}
{}
GCSFilter::GCSFilter(const Params& params, std::vector<unsigned char> encoded_filter)
: m_params(params), m_encoded(std::move(encoded_filter))
{
SpanReader stream{GCS_SER_TYPE, GCS_SER_VERSION, m_encoded};
uint64_t N = ReadCompactSize(stream);
m_N = static_cast<uint32_t>(N);
if (m_N != N) {
throw std::ios_base::failure("N must be <2^32");
}
m_F = static_cast<uint64_t>(m_N) * static_cast<uint64_t>(m_params.m_M);
// Verify that the encoded filter contains exactly N elements. If it has too much or too little
// data, a std::ios_base::failure exception will be raised.
BitStreamReader<SpanReader> bitreader{stream};
for (uint64_t i = 0; i < m_N; ++i) {
GolombRiceDecode(bitreader, m_params.m_P);
}
if (!stream.empty()) {
throw std::ios_base::failure("encoded_filter contains excess data");
}
}
GCSFilter::GCSFilter(const Params& params, const ElementSet& elements)
: m_params(params)
{
size_t N = elements.size();
m_N = static_cast<uint32_t>(N);
if (m_N != N) {
throw std::invalid_argument("N must be <2^32");
}
m_F = static_cast<uint64_t>(m_N) * static_cast<uint64_t>(m_params.m_M);
CVectorWriter stream(GCS_SER_TYPE, GCS_SER_VERSION, m_encoded, 0);
WriteCompactSize(stream, m_N);
if (elements.empty()) {
return;
}
BitStreamWriter<CVectorWriter> bitwriter(stream);
uint64_t last_value = 0;
for (uint64_t value : BuildHashedSet(elements)) {
uint64_t delta = value - last_value;
GolombRiceEncode(bitwriter, m_params.m_P, delta);
last_value = value;
}
bitwriter.Flush();
}
bool GCSFilter::MatchInternal(const uint64_t* element_hashes, size_t size) const
{
SpanReader stream{GCS_SER_TYPE, GCS_SER_VERSION, m_encoded};
// Seek forward by size of N
uint64_t N = ReadCompactSize(stream);
assert(N == m_N);
BitStreamReader<SpanReader> bitreader{stream};
uint64_t value = 0;
size_t hashes_index = 0;
for (uint32_t i = 0; i < m_N; ++i) {
uint64_t delta = GolombRiceDecode(bitreader, m_params.m_P);
value += delta;
while (true) {
if (hashes_index == size) {
return false;
} else if (element_hashes[hashes_index] == value) {
return true;
} else if (element_hashes[hashes_index] > value) {
break;
}
hashes_index++;
}
}
return false;
}
bool GCSFilter::Match(const Element& element) const
{
uint64_t query = HashToRange(element);
return MatchInternal(&query, 1);
}
bool GCSFilter::MatchAny(const ElementSet& elements) const
{
const std::vector<uint64_t> queries = BuildHashedSet(elements);
return MatchInternal(queries.data(), queries.size());
}
const std::string& BlockFilterTypeName(BlockFilterType filter_type)
{
static std::string unknown_retval = "";
auto it = g_filter_types.find(filter_type);
return it != g_filter_types.end() ? it->second : unknown_retval;
}
bool BlockFilterTypeByName(const std::string& name, BlockFilterType& filter_type) {
for (const auto& entry : g_filter_types) {
if (entry.second == name) {
filter_type = entry.first;
return true;
}
}
return false;
}
const std::set<BlockFilterType>& AllBlockFilterTypes()
{
static std::set<BlockFilterType> types;
static std::once_flag flag;
std::call_once(flag, []() {
for (auto entry : g_filter_types) {
types.insert(entry.first);
}
});
return types;
}
const std::string& ListBlockFilterTypes()
{
static std::string type_list;
static std::once_flag flag;
std::call_once(flag, []() {
std::stringstream ret;
bool first = true;
for (auto entry : g_filter_types) {
if (!first) ret << ", ";
ret << entry.second;
first = false;
}
type_list = ret.str();
});
return type_list;
}
static GCSFilter::ElementSet BasicFilterElements(const CBlock& block,
const CBlockUndo& block_undo)
{
GCSFilter::ElementSet elements;
for (const CTransactionRef& tx : block.vtx) {
for (const CTxOut& txout : tx->vout) {
const CScript& script = txout.scriptPubKey;
if (script.empty() || script[0] == OP_RETURN) continue;
elements.emplace(script.begin(), script.end());
}
}
for (const CTxUndo& tx_undo : block_undo.vtxundo) {
for (const Coin& prevout : tx_undo.vprevout) {
const CScript& script = prevout.out.scriptPubKey;
if (script.empty()) continue;
elements.emplace(script.begin(), script.end());
}
}
return elements;
}
BlockFilter::BlockFilter(BlockFilterType filter_type, const uint256& block_hash,
std::vector<unsigned char> filter)
: m_filter_type(filter_type), m_block_hash(block_hash)
{
GCSFilter::Params params;
if (!BuildParams(params)) {
throw std::invalid_argument("unknown filter_type");
}
m_filter = GCSFilter(params, std::move(filter));
}
BlockFilter::BlockFilter(BlockFilterType filter_type, const CBlock& block, const CBlockUndo& block_undo)
: m_filter_type(filter_type), m_block_hash(block.GetHash())
{
GCSFilter::Params params;
if (!BuildParams(params)) {
throw std::invalid_argument("unknown filter_type");
}
m_filter = GCSFilter(params, BasicFilterElements(block, block_undo));
}
bool BlockFilter::BuildParams(GCSFilter::Params& params) const
{
switch (m_filter_type) {
case BlockFilterType::BASIC:
params.m_siphash_k0 = m_block_hash.GetUint64(0);
params.m_siphash_k1 = m_block_hash.GetUint64(1);
params.m_P = BASIC_FILTER_P;
params.m_M = BASIC_FILTER_M;
return true;
case BlockFilterType::INVALID:
return false;
}
return false;
}
uint256 BlockFilter::GetHash() const
{
const std::vector<unsigned char>& data = GetEncodedFilter();
uint256 result;
CHash256().Write(data).Finalize(result);
return result;
}
uint256 BlockFilter::ComputeHeader(const uint256& prev_header) const
{
const uint256& filter_hash = GetHash();
uint256 result;
CHash256()
.Write(filter_hash)
.Write(prev_header)
.Finalize(result);
return result;
}