1// Copyright (c) 2009-2010 Satoshi Nakamoto
2// Copyright (c) 2009-present The Bitcoin Core developers
3// Distributed under the MIT software license, see the accompanying
4// file COPYING or http://www.opensource.org/licenses/mit-license.php.
5
6#ifndef BITCOIN_NODE_UTXO_SNAPSHOT_H
7#define BITCOIN_NODE_UTXO_SNAPSHOT_H
8
9#include <kernel/chainparams.h>
10#include <kernel/cs_main.h>
11#include <kernel/messagestartchars.h>
12#include <sync.h>
13#include <tinyformat.h>
14#include <uint256.h>
15#include <util/chaintype.h>
16#include <util/fs.h>
17
18#include <algorithm>
19#include <array>
20#include <cstdint>
21#include <ios>
22#include <optional>
23#include <set>
24#include <string>
25#include <string_view>
26
27// UTXO set snapshot magic bytes
28inline constexpr std::array<uint8_t, 5> SNAPSHOT_MAGIC_BYTES = {'u', 't', 'x', 'o', 0xff};
29
30class Chainstate;
31
32namespace node {
33//! Metadata describing a serialized version of a UTXO set from which an
34//! assumeutxo Chainstate can be constructed.
35//! All metadata fields come from an untrusted file, so must be validated
36//! before being used. Thus, new fields should be added only if needed.
37class SnapshotMetadata
38{
39    static constexpr uint16_t VERSION{2};
40    const std::set<uint16_t> m_supported_versions{VERSION};
41    const MessageStartChars m_network_magic;
42public:
43    //! The hash of the block that reflects the tip of the chain for the
44    //! UTXO set contained in this snapshot.
45    uint256 m_base_blockhash;
46
47
48    //! The number of coins in the UTXO set contained in this snapshot. Used
49    //! during snapshot load to estimate progress of UTXO set reconstruction.
50    uint64_t m_coins_count = 0;
51
52    SnapshotMetadata(
53        const MessageStartChars network_magic) :
54            m_network_magic(network_magic) { }
55    SnapshotMetadata(
56        const MessageStartChars network_magic,
57        const uint256& base_blockhash,
58        uint64_t coins_count) :
59            m_network_magic(network_magic),
60            m_base_blockhash(base_blockhash),
61            m_coins_count(coins_count) { }
62
63    template <typename Stream>
64    inline void Serialize(Stream& s) const {
65        s << SNAPSHOT_MAGIC_BYTES;
66        s << VERSION;
67        s << m_network_magic;
68        s << m_base_blockhash;
69        s << m_coins_count;
70    }
71
72    template <typename Stream>
73    inline void Unserialize(Stream& s) {
74        // Read the snapshot magic bytes
75        std::array<uint8_t, SNAPSHOT_MAGIC_BYTES.size()> snapshot_magic;
76        s >> snapshot_magic;
77        if (snapshot_magic != SNAPSHOT_MAGIC_BYTES) {
78            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.");
79        }
80
81        // Read the version
82        uint16_t version;
83        s >> version;
84        if (!m_supported_versions.contains(version)) {
85            throw std::ios_base::failure(strprintf("Version of snapshot %s does not match any of the supported versions.", version));
86        }
87
88        // Read the network magic (pchMessageStart)
89        MessageStartChars message;
90        s >> message;
91        if (!std::equal(message.begin(), message.end(), m_network_magic.data())) {
92            auto metadata_network{GetNetworkForMagic(message)};
93            if (metadata_network) {
94                std::string network_string{ChainTypeToString(metadata_network.value())};
95                auto node_network{GetNetworkForMagic(m_network_magic)};
96                std::string node_network_string{ChainTypeToString(node_network.value())};
97                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));
98            } else {
99                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.");
100            }
101        }
102
103        s >> m_base_blockhash;
104        s >> m_coins_count;
105    }
106};
107
108//! The file in the snapshot chainstate dir which stores the base blockhash. This is
109//! needed to reconstruct snapshot chainstates on init.
110//!
111//! Because we only allow loading a single snapshot at a time, there will only be one
112//! chainstate directory with this filename present within it.
113inline const fs::path SNAPSHOT_BLOCKHASH_FILENAME{"base_blockhash"};
114
115//! Write out the blockhash of the snapshot base block that was used to construct
116//! this chainstate. This value is read in during subsequent initializations and
117//! used to reconstruct snapshot-based chainstates.
118bool WriteSnapshotBaseBlockhash(Chainstate& snapshot_chainstate)
119    EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
120
121//! Read the blockhash of the snapshot base block that was used to construct the
122//! chainstate.
123std::optional<uint256> ReadSnapshotBaseBlockhash(fs::path chaindir)
124    EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
125
126//! Suffix appended to the chainstate (leveldb) dir when created based upon
127//! a snapshot.
128inline constexpr std::string_view SNAPSHOT_CHAINSTATE_SUFFIX = "_snapshot";
129
130
131//! Return a path to the snapshot-based chainstate dir, if one exists.
132std::optional<fs::path> FindAssumeutxoChainstateDir(const fs::path& data_dir);
133
134} // namespace node
135
136#endif // BITCOIN_NODE_UTXO_SNAPSHOT_H
137