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       1                 :             : // Copyright (c) 2023-present The Bitcoin Core developers
       2                 :             : // Distributed under the MIT software license, see the accompanying
       3                 :             : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
       4                 :             : 
       5                 :             : #ifndef BITCOIN_TEST_FUZZ_UTIL_DESCRIPTOR_H
       6                 :             : #define BITCOIN_TEST_FUZZ_UTIL_DESCRIPTOR_H
       7                 :             : 
       8                 :             : #include <key_io.h>
       9                 :             : #include <util/strencodings.h>
      10                 :             : #include <script/descriptor.h>
      11                 :             : #include <test/fuzz/fuzz.h>
      12                 :             : 
      13                 :             : #include <functional>
      14                 :             : 
      15                 :             : /**
      16                 :             :  * Converts a mocked descriptor string to a valid one. Every key in a mocked descriptor key is
      17                 :             :  * represented by 2 hex characters preceded by the '%' character. We parse the two hex characters
      18                 :             :  * as an index in a list of pre-generated keys. This list contains keys of the various types
      19                 :             :  * accepted in descriptor keys expressions.
      20                 :             :  */
      21                 :             : class MockedDescriptorConverter {
      22                 :             : private:
      23                 :             :     //! Types are raw (un)compressed pubkeys, raw xonly pubkeys, raw privkeys (WIF), xpubs, xprvs.
      24                 :             :     static constexpr uint8_t KEY_TYPES_COUNT{6};
      25                 :             :     //! How many keys we'll generate in total.
      26                 :             :     static constexpr size_t TOTAL_KEYS_GENERATED{std::numeric_limits<uint8_t>::max() + 1};
      27                 :             :     //! 256 keys of various types.
      28                 :             :     std::array<std::string, TOTAL_KEYS_GENERATED> keys_str;
      29                 :             : 
      30                 :             : public:
      31                 :             :     // We derive the type of key to generate from the 1-byte id parsed from hex.
      32         [ #  # ]:           0 :     bool IdIsCompPubKey(uint8_t idx) const { return idx % KEY_TYPES_COUNT == 0; }
      33                 :             :     bool IdIsUnCompPubKey(uint8_t idx) const { return idx % KEY_TYPES_COUNT == 1; }
      34                 :             :     bool IdIsXOnlyPubKey(uint8_t idx) const { return idx % KEY_TYPES_COUNT == 2; }
      35                 :             :     bool IdIsConstPrivKey(uint8_t idx) const { return idx % KEY_TYPES_COUNT == 3; }
      36                 :             :     bool IdIsXpub(uint8_t idx) const { return idx % KEY_TYPES_COUNT == 4; }
      37                 :             :     bool IdIsXprv(uint8_t idx) const { return idx % KEY_TYPES_COUNT == 5; }
      38                 :             : 
      39                 :             :     //! When initializing the target, populate the list of keys.
      40                 :             :     void Init();
      41                 :             : 
      42                 :             :     //! Parse an id in the keys vectors from a 2-characters hex string.
      43                 :             :     std::optional<uint8_t> IdxFromHex(std::string_view hex_characters) const;
      44                 :             : 
      45                 :             :     //! Get an actual descriptor string from a descriptor string whose keys were mocked.
      46                 :             :     std::optional<std::string> GetDescriptor(std::string_view mocked_desc) const;
      47                 :             : };
      48                 :             : 
      49                 :             : //! Default maximum number of derivation indexes in a single derivation path when limiting its depth.
      50                 :             : constexpr int MAX_DEPTH{2};
      51                 :             : 
      52                 :             : /**
      53                 :             :  * Whether the buffer, if it represents a valid descriptor, contains a derivation path deeper than
      54                 :             :  * a given maximum depth. Note this may also be hit for deriv paths in origins.
      55                 :             :  */
      56                 :             : bool HasDeepDerivPath(const FuzzBufferType& buff, const int max_depth = MAX_DEPTH);
      57                 :             : 
      58                 :             : //! Default maximum number of sub-fragments.
      59                 :             : constexpr int MAX_SUBS{1'000};
      60                 :             : //! Maximum number of nested sub-fragments we'll allow in a descriptor.
      61                 :             : constexpr size_t MAX_NESTED_SUBS{10'000};
      62                 :             : 
      63                 :             : /**
      64                 :             :  * Whether the buffer, if it represents a valid descriptor, contains a fragment with more
      65                 :             :  * sub-fragments than the given maximum.
      66                 :             :  */
      67                 :             : bool HasTooManySubFrag(const FuzzBufferType& buff, const int max_subs = MAX_SUBS,
      68                 :             :                        const size_t max_nested_subs = MAX_NESTED_SUBS);
      69                 :             : 
      70                 :             : //! Default maximum number of wrappers per fragment.
      71                 :             : constexpr int MAX_WRAPPERS{100};
      72                 :             : 
      73                 :             : /**
      74                 :             :  * Whether the buffer, if it represents a valid descriptor, contains a fragment with more
      75                 :             :  * wrappers than the given maximum.
      76                 :             :  */
      77                 :             : bool HasTooManyWrappers(const FuzzBufferType& buff, const int max_wrappers = MAX_WRAPPERS);
      78                 :             : 
      79                 :             : #endif // BITCOIN_TEST_FUZZ_UTIL_DESCRIPTOR_H