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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2022 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_NODE_UTXO_SNAPSHOT_H
#define BITCOIN_NODE_UTXO_SNAPSHOT_H
#include <chainparams.h>
#include <kernel/chainparams.h>
#include <kernel/cs_main.h>
#include <serialize.h>
#include <sync.h>
#include <uint256.h>
#include <util/chaintype.h>
#include <util/check.h>
#include <util/fs.h>
#include <cstdint>
#include <optional>
#include <string_view>
// UTXO set snapshot magic bytes
static constexpr std::array<uint8_t, 5> SNAPSHOT_MAGIC_BYTES = {'u', 't', 'x', 'o', 0xff};
class Chainstate;
namespace node {
//! Metadata describing a serialized version of a UTXO set from which an
//! assumeutxo Chainstate can be constructed.
//! All metadata fields come from an untrusted file, so must be validated
//! before being used. Thus, new fields should be added only if needed.
class SnapshotMetadata
{
inline static const uint16_t VERSION{2};
const std::set<uint16_t> m_supported_versions{VERSION};
const MessageStartChars m_network_magic;
public:
//! The hash of the block that reflects the tip of the chain for the
//! UTXO set contained in this snapshot.
uint256 m_base_blockhash;
//! The number of coins in the UTXO set contained in this snapshot. Used
//! during snapshot load to estimate progress of UTXO set reconstruction.
uint64_t m_coins_count = 0;
SnapshotMetadata(
const MessageStartChars network_magic) :
m_network_magic(network_magic) { }
SnapshotMetadata(
const MessageStartChars network_magic,
const uint256& base_blockhash,
uint64_t coins_count) :
m_network_magic(network_magic),
m_base_blockhash(base_blockhash),
m_coins_count(coins_count) { }
template <typename Stream>
inline void Serialize(Stream& s) const {
s << SNAPSHOT_MAGIC_BYTES;
s << VERSION;
s << m_network_magic;
s << m_base_blockhash;
s << m_coins_count;
}
template <typename Stream>
inline void Unserialize(Stream& s) {
// Read the snapshot magic bytes
std::array<uint8_t, SNAPSHOT_MAGIC_BYTES.size()> snapshot_magic;
s >> snapshot_magic;
if (snapshot_magic != SNAPSHOT_MAGIC_BYTES) {
throw std::ios_base::failure("Invalid UTXO set snapshot magic bytes. Please check if this is indeed a snapshot file or if you are using an outdated snapshot format.");
}
// Read the version
uint16_t version;
s >> version;
if (m_supported_versions.find(version) == m_supported_versions.end()) {
throw std::ios_base::failure(strprintf("Version of snapshot %s does not match any of the supported versions.", version));
}
// Read the network magic (pchMessageStart)
MessageStartChars message;
s >> message;
if (!std::equal(message.begin(), message.end(), m_network_magic.data())) {
auto metadata_network{GetNetworkForMagic(message)};
if (metadata_network) {
std::string network_string{ChainTypeToString(metadata_network.value())};
auto node_network{GetNetworkForMagic(m_network_magic)};
std::string node_network_string{ChainTypeToString(node_network.value())};
throw std::ios_base::failure(strprintf("The network of the snapshot (%s) does not match the network of this node (%s).", network_string, node_network_string));
} else {
throw std::ios_base::failure("This snapshot has been created for an unrecognized network. This could be a custom signet, a new testnet or possibly caused by data corruption.");
}
}
s >> m_base_blockhash;
s >> m_coins_count;
}
};
//! The file in the snapshot chainstate dir which stores the base blockhash. This is
//! needed to reconstruct snapshot chainstates on init.
//!
//! Because we only allow loading a single snapshot at a time, there will only be one
//! chainstate directory with this filename present within it.
const fs::path SNAPSHOT_BLOCKHASH_FILENAME{"base_blockhash"};
//! Write out the blockhash of the snapshot base block that was used to construct
//! this chainstate. This value is read in during subsequent initializations and
//! used to reconstruct snapshot-based chainstates.
bool WriteSnapshotBaseBlockhash(Chainstate& snapshot_chainstate)
EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
//! Read the blockhash of the snapshot base block that was used to construct the
//! chainstate.
std::optional<uint256> ReadSnapshotBaseBlockhash(fs::path chaindir)
EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
//! Suffix appended to the chainstate (leveldb) dir when created based upon
//! a snapshot.
constexpr std::string_view SNAPSHOT_CHAINSTATE_SUFFIX = "_snapshot";
//! Return a path to the snapshot-based chainstate dir, if one exists.
std::optional<fs::path> FindSnapshotChainstateDir(const fs::path& data_dir);
} // namespace node
#endif // BITCOIN_NODE_UTXO_SNAPSHOT_H
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