walletutil.h

// Copyright (c) 2017-present 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_WALLET_WALLETUTIL_H
#define BITCOIN_WALLET_WALLETUTIL_H

#include <script/descriptor.h>
#include <util/fs.h>

#include <vector>

namespace wallet {

enum WalletFlags : uint64_t {
    // wallet flags in the upper section (> 1 << 31) will lead to not opening the wallet if flag is unknown
    // unknown wallet flags in the lower section <= (1 << 31) will be tolerated

    // will categorize coins as clean (not reused) and dirty (reused), and handle
    // them with privacy considerations in mind
    WALLET_FLAG_AVOID_REUSE = (1ULL << 0),

    // Indicates that the metadata has already been upgraded to contain key origins
    WALLET_FLAG_KEY_ORIGIN_METADATA = (1ULL << 1),

    // Indicates that the descriptor cache has been upgraded to cache last hardened xpubs
    WALLET_FLAG_LAST_HARDENED_XPUB_CACHED = (1ULL << 2),

    // will enforce the rule that the wallet can't contain any private keys (only watch-only/pubkeys)
    WALLET_FLAG_DISABLE_PRIVATE_KEYS = (1ULL << 32),

    //! Flag set when a wallet contains no HD seed and no private keys, scripts,
    //! addresses, and other watch only things, and is therefore "blank."
    //!
    //! The main function this flag serves is to distinguish a blank wallet from
    //! a newly created wallet when the wallet database is loaded, to avoid
    //! initialization that should only happen on first run.
    //!
    //! A secondary function of this flag, which applies to descriptor wallets
    //! only, is to serve as an ongoing indication that descriptors in the
    //! wallet should be created manually, and that the wallet should not
    //! generate automatically generate new descriptors if it is later
    //! encrypted. To support this behavior, descriptor wallets unlike legacy
    //! wallets do not automatically unset the BLANK flag when things are
    //! imported.
    //!
    //! This flag is also a mandatory flag to prevent previous versions of
    //! bitcoin from opening the wallet, thinking it was newly created, and
    //! then improperly reinitializing it.
    WALLET_FLAG_BLANK_WALLET = (1ULL << 33),

    //! Indicate that this wallet supports DescriptorScriptPubKeyMan
    WALLET_FLAG_DESCRIPTORS = (1ULL << 34),

    //! Indicates that the wallet needs an external signer
    WALLET_FLAG_EXTERNAL_SIGNER = (1ULL << 35),
};

// Version numbers for the wallet client that opens a wallet
// These numbers will be written as the last client version in the "version" record and can be used to detect
// when an upgrade-downgrade-upgrade was performed. However, we should prefer to use LastClientFeatures rather
// than new version numbers.
// New version numbers must be greater than 329900 which is guaranteed by setting bit 19
enum WalletClientVersion : int32_t {
    MIN_VERSION = (1L << 19),

    // The wallet client supports the records for LastClientFeatures
    VERSION_LAST_CLIENT_FEATURES = MIN_VERSION + 1,

    VERSION_LATEST = VERSION_LAST_CLIENT_FEATURES
};

enum LastClientFeatures : uint64_t {
    // Flags indicating the automatic upgrade features supported by the wallet client that last opened a wallet file
    // New automatic upgrades must define a flag here so that upgrade-downgrade-upgrade can be detected to determine whether
    // an automatic upgrade should be performed.

    WALLET_CLIENT_FEATURES = 0
};

//! Get the path of the wallet directory.
fs::path GetWalletDir();

/** Descriptor with some wallet metadata */
class WalletDescriptor
{
private:
    int32_t range_start = 0; // First item in range; start of range, inclusive, i.e. [range_start, range_end). This never changes.
    int32_t next_index = 0; // Position of the next item to generate
    int32_t range_end = 0; // Item after the last; end of range, exclusive, i.e. [range_start, range_end). This will increment with each TopUp()

    mutable std::optional<uint256> m_canonical_hash; // Hash of the canonical string, used as a shortcut for comparing canonical strings

    uint256 GetCanonicalHash() const;

public:
    const std::shared_ptr<const Descriptor> descriptor;
    uint64_t creation_time = 0;
    DescriptorCache cache;

    int32_t GetStart() const { return range_start; }
    int32_t GetNext() const { return next_index; }
    int32_t GetEnd() const { return range_end; }

    //! Increments the next_index of the descriptor.
    void IncNext()
    {
        next_index++;
    }

    //! Increments the next_index of the descriptor.
    void DecNext()
    {
        next_index--;
    }

    //! Sets the range_end of the descriptor.
    void SetEnd(int32_t end)
    {
        if (!descriptor->IsRange()) {
            CHECK_NONFATAL(end == 1);
        }
        range_end = end;
    }

    template <typename Stream>
    void Serialize(Stream& s) const
    {
        std::string descriptor_str = descriptor->ToString();
        s << descriptor_str << creation_time << next_index << range_start << range_end;
    }

    template <typename Stream>
    static WalletDescriptor FromStream(deserialize_type, Stream& s)
    {
        std::string descriptor_str;
        uint64_t creation_time;
        int32_t next_index, range_start, range_end;
        s >> descriptor_str >> creation_time >> next_index >> range_start >> range_end;

        std::string error;
        FlatSigningProvider keys;
        auto descs = Parse(descriptor_str, keys, error, true);
        if (descs.empty()) {
            throw std::ios_base::failure("Invalid descriptor: " + error);
        }
        if (descs.size() > 1) {
            throw std::ios_base::failure("Can't load a multipath descriptor from databases");
        }
        return WalletDescriptor(std::move(descs.at(0)), creation_time, range_start, range_end, next_index);
    }

    WalletDescriptor() = delete;
    WalletDescriptor(std::shared_ptr<Descriptor> descriptor, uint64_t creation_time, int32_t range_start, int32_t range_end, int32_t next_index)
    : range_start(descriptor->IsRange() ? range_start : 0),
      next_index(next_index),
      range_end(descriptor->IsRange() ? range_end : 1),
      descriptor(descriptor),
      creation_time(creation_time)
    {}

    /** Replaces all metadata (range, start, end, creation time), and cache from another WalletDescriptor if it has the same canonical descriptor string.
     *  The descriptor itself is not replaced to preserve existing serialization to maintain compatibility with previous software versions that expect
     *  specific serialization.
     */
    void UpdateFrom(const WalletDescriptor& other);

    // Compare by using the canonical string to make the hardened indicators consistent for comparison
    bool IsCanonicallyEquivalent(const WalletDescriptor& other) const;
};

WalletDescriptor GenerateWalletDescriptor(const CExtPubKey& master_key, const OutputType& output_type, bool internal);
} // namespace wallet

#endif // BITCOIN_WALLET_WALLETUTIL_H