Line data    Source code

       1             : // Copyright (c) 2009-2021 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             : #include <chainparams.h>
       6             : #include <key_io.h>
       7             : #include <pubkey.h>
       8             : #include <script/descriptor.h>
       9             : #include <test/fuzz/fuzz.h>
      10             : #include <util/chaintype.h>
      11             : #include <util/strencodings.h>
      12             : 
      13             : //! Types are raw (un)compressed pubkeys, raw xonly pubkeys, raw privkeys (WIF), xpubs, xprvs.
      14             : static constexpr uint8_t KEY_TYPES_COUNT{6};
      15             : //! How many keys we'll generate in total.
      16             : static constexpr size_t TOTAL_KEYS_GENERATED{std::numeric_limits<uint8_t>::max() + 1};
      17             : 
      18             : /**
      19             :  * Converts a mocked descriptor string to a valid one. Every key in a mocked descriptor key is
      20             :  * represented by 2 hex characters preceded by the '%' character. We parse the two hex characters
      21             :  * as an index in a list of pre-generated keys. This list contains keys of the various types
      22             :  * accepted in descriptor keys expressions.
      23             :  */
      24             : class MockedDescriptorConverter {
      25             :     //! 256 keys of various types.
      26             :     std::array<std::string, TOTAL_KEYS_GENERATED> keys_str;
      27             : 
      28             : public:
      29             :     // We derive the type of key to generate from the 1-byte id parsed from hex.
      30           0 :     bool IdIsCompPubKey(uint8_t idx) const { return idx % KEY_TYPES_COUNT == 0; }
      31           0 :     bool IdIsUnCompPubKey(uint8_t idx) const { return idx % KEY_TYPES_COUNT == 1; }
      32           0 :     bool IdIsXOnlyPubKey(uint8_t idx) const { return idx % KEY_TYPES_COUNT == 2; }
      33           0 :     bool IdIsConstPrivKey(uint8_t idx) const { return idx % KEY_TYPES_COUNT == 3; }
      34             :     bool IdIsXpub(uint8_t idx) const { return idx % KEY_TYPES_COUNT == 4; }
      35           0 :     bool IdIsXprv(uint8_t idx) const { return idx % KEY_TYPES_COUNT == 5; }
      36             : 
      37             :     //! When initializing the target, populate the list of keys.
      38           0 :     void Init() {
      39             :         // The data to use as a private key or a seed for an xprv.
      40           0 :         std::array<std::byte, 32> key_data{std::byte{1}};
      41             :         // Generate keys of all kinds and store them in the keys array.
      42           0 :         for (size_t i{0}; i < TOTAL_KEYS_GENERATED; i++) {
      43           0 :             key_data[31] = std::byte(i);
      44             : 
      45             :             // If this is a "raw" key, generate a normal privkey. Otherwise generate
      46             :             // an extended one.
      47           0 :             if (IdIsCompPubKey(i) || IdIsUnCompPubKey(i) || IdIsXOnlyPubKey(i) || IdIsConstPrivKey(i)) {
      48           0 :                 CKey privkey;
      49           0 :                 privkey.Set(UCharCast(key_data.begin()), UCharCast(key_data.end()), !IdIsUnCompPubKey(i));
      50           0 :                 if (IdIsCompPubKey(i) || IdIsUnCompPubKey(i)) {
      51           0 :                     CPubKey pubkey{privkey.GetPubKey()};
      52           0 :                     keys_str[i] = HexStr(pubkey);
      53           0 :                 } else if (IdIsXOnlyPubKey(i)) {
      54           0 :                     const XOnlyPubKey pubkey{privkey.GetPubKey()};
      55           0 :                     keys_str[i] = HexStr(pubkey);
      56           0 :                 } else {
      57           0 :                     keys_str[i] = EncodeSecret(privkey);
      58             :                 }
      59           0 :             } else {
      60           0 :                 CExtKey ext_privkey;
      61           0 :                 ext_privkey.SetSeed(key_data);
      62           0 :                 if (IdIsXprv(i)) {
      63           0 :                     keys_str[i] = EncodeExtKey(ext_privkey);
      64           0 :                 } else {
      65           0 :                     const CExtPubKey ext_pubkey{ext_privkey.Neuter()};
      66           0 :                     keys_str[i] = EncodeExtPubKey(ext_pubkey);
      67             :                 }
      68           0 :             }
      69           0 :         }
      70           0 :     }
      71             : 
      72             :     //! Parse an id in the keys vectors from a 2-characters hex string.
      73           0 :     std::optional<uint8_t> IdxFromHex(std::string_view hex_characters) const {
      74           0 :         if (hex_characters.size() != 2) return {};
      75           0 :         auto idx = ParseHex(hex_characters);
      76           0 :         if (idx.size() != 1) return {};
      77           0 :         return idx[0];
      78           0 :     }
      79             : 
      80             :     //! Get an actual descriptor string from a descriptor string whose keys were mocked.
      81           0 :     std::optional<std::string> GetDescriptor(std::string_view mocked_desc) const {
      82             :         // The smallest fragment would be "pk(%00)"
      83           0 :         if (mocked_desc.size() < 7) return {};
      84             : 
      85             :         // The actual descriptor string to be returned.
      86           0 :         std::string desc;
      87           0 :         desc.reserve(mocked_desc.size());
      88             : 
      89             :         // Replace all occurrences of '%' followed by two hex characters with the corresponding key.
      90           0 :         for (size_t i = 0; i < mocked_desc.size();) {
      91           0 :             if (mocked_desc[i] == '%') {
      92           0 :                 if (i + 3 >= mocked_desc.size()) return {};
      93           0 :                 if (const auto idx = IdxFromHex(mocked_desc.substr(i + 1, 2))) {
      94           0 :                     desc += keys_str[*idx];
      95           0 :                     i += 3;
      96           0 :                 } else {
      97           0 :                     return {};
      98             :                 }
      99           0 :             } else {
     100           0 :                 desc += mocked_desc[i++];
     101             :             }
     102             :         }
     103             : 
     104           0 :         return desc;
     105           0 :     }
     106             : };
     107             : 
     108             : //! The converter of mocked descriptors, needs to be initialized when the target is.
     109           2 : MockedDescriptorConverter MOCKED_DESC_CONVERTER;
     110             : 
     111             : /** Test a successfully parsed descriptor. */
     112           0 : static void TestDescriptor(const Descriptor& desc, FlatSigningProvider& sig_provider, std::string& dummy)
     113             : {
     114             :     // Trivial helpers.
     115           0 :     (void)desc.IsRange();
     116           0 :     const bool is_solvable{desc.IsSolvable()};
     117           0 :     (void)desc.IsSingleType();
     118           0 :     (void)desc.GetOutputType();
     119             : 
     120             :     // Serialization to string representation.
     121           0 :     (void)desc.ToString();
     122           0 :     (void)desc.ToPrivateString(sig_provider, dummy);
     123           0 :     (void)desc.ToNormalizedString(sig_provider, dummy);
     124             : 
     125             :     // Serialization to Script.
     126           0 :     DescriptorCache cache;
     127           0 :     std::vector<CScript> out_scripts;
     128           0 :     (void)desc.Expand(0, sig_provider, out_scripts, sig_provider, &cache);
     129           0 :     (void)desc.ExpandPrivate(0, sig_provider, sig_provider);
     130           0 :     (void)desc.ExpandFromCache(0, cache, out_scripts, sig_provider);
     131             : 
     132             :     // If we could serialize to script we must be able to infer using the same provider.
     133           0 :     if (!out_scripts.empty()) {
     134           0 :         assert(InferDescriptor(out_scripts.back(), sig_provider));
     135             : 
     136             :         // The ScriptSize() must match the size of the serialized Script. (ScriptSize() is set for all descs but 'combo()'.)
     137           0 :         const bool is_combo{!desc.IsSingleType()};
     138           0 :         assert(is_combo || desc.ScriptSize() == out_scripts.back().size());
     139           0 :     }
     140             : 
     141           0 :     const auto max_sat_maxsig{desc.MaxSatisfactionWeight(true)};
     142           0 :     const auto max_sat_nonmaxsig{desc.MaxSatisfactionWeight(true)};
     143           0 :     const auto max_elems{desc.MaxSatisfactionElems()};
     144             :     // We must be able to estimate the max satisfaction size for any solvable descriptor (but combo).
     145           0 :     const bool is_nontop_or_nonsolvable{!is_solvable || !desc.GetOutputType()};
     146           0 :     const bool is_input_size_info_set{max_sat_maxsig && max_sat_nonmaxsig && max_elems};
     147           0 :     assert(is_input_size_info_set || is_nontop_or_nonsolvable);
     148           0 : }
     149             : 
     150           0 : void initialize_descriptor_parse()
     151             : {
     152           0 :     ECC_Start();
     153           0 :     SelectParams(ChainType::MAIN);
     154           0 : }
     155             : 
     156           0 : void initialize_mocked_descriptor_parse()
     157             : {
     158           0 :     initialize_descriptor_parse();
     159           0 :     MOCKED_DESC_CONVERTER.Init();
     160           0 : }
     161             : 
     162           4 : FUZZ_TARGET(mocked_descriptor_parse, .init = initialize_mocked_descriptor_parse)
     163             : {
     164           0 :     const std::string mocked_descriptor{buffer.begin(), buffer.end()};
     165           0 :     if (const auto descriptor = MOCKED_DESC_CONVERTER.GetDescriptor(mocked_descriptor)) {
     166           0 :         FlatSigningProvider signing_provider;
     167           0 :         std::string error;
     168           0 :         const auto desc = Parse(*descriptor, signing_provider, error);
     169           0 :         if (desc) TestDescriptor(*desc, signing_provider, error);
     170           0 :     }
     171           0 : }
     172             : 
     173           4 : FUZZ_TARGET(descriptor_parse, .init = initialize_descriptor_parse)
     174             : {
     175           0 :     const std::string descriptor(buffer.begin(), buffer.end());
     176           0 :     FlatSigningProvider signing_provider;
     177           0 :     std::string error;
     178           0 :     for (const bool require_checksum : {true, false}) {
     179           0 :         const auto desc = Parse(descriptor, signing_provider, error, require_checksum);
     180           0 :         if (desc) TestDescriptor(*desc, signing_provider, error);
     181           0 :     }
     182           0 : }