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
 28  static constexpr std::array<uint8_t, 5> SNAPSHOT_MAGIC_BYTES = {'u', 't', 'x', 'o', 0xff};
 29  
 30  class Chainstate;
 31  
 32  namespace 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.
 37  class SnapshotMetadata
 38  {
 39      inline static const uint16_t VERSION{2};
 40      const std::set<uint16_t> m_supported_versions{VERSION};
 41      const MessageStartChars m_network_magic;
 42  public:
 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.
113  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.
118  bool 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.
123  std::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.
128  constexpr std::string_view SNAPSHOT_CHAINSTATE_SUFFIX = "_snapshot";
129  
130  
131  //! Return a path to the snapshot-based chainstate dir, if one exists.
132  std::optional<fs::path> FindAssumeutxoChainstateDir(const fs::path& data_dir);
133  
134  } // namespace node
135  
136  #endif // BITCOIN_NODE_UTXO_SNAPSHOT_H