fuzz: wallet: add target for spkm migration

src/wallet/test/fuzz/scriptpubkeyman.cpp

@@ -49,6 +49,13 @@ void initialize_spkm()
     MOCKED_DESC_CONVERTER.Init();
 }
 
+void initialize_spkm_migration()
+{
+    static const auto testing_setup{MakeNoLogFileContext<const TestingSetup>()};
+    g_setup = testing_setup.get();
+    SelectParams(ChainType::MAIN);
+}
+
 /**
  * Key derivation is expensive. Deriving deep derivation paths take a lot of compute and we'd rather spend time
  * elsewhere in this target, like on actually fuzzing the DescriptorScriptPubKeyMan. So rule out strings which could
@@ -200,5 +207,104 @@ FUZZ_TARGET(scriptpubkeyman, .init = initialize_spkm)
     (void)spk_manager->GetKeyPoolSize();
 }
 
+FUZZ_TARGET(spkm_migration, .init = initialize_spkm_migration)
+{
+    FuzzedDataProvider fuzzed_data_provider{buffer.data(), buffer.size()};
+    const auto& node{g_setup->m_node};
+    Chainstate& chainstate{node.chainman->ActiveChainstate()};
+    std::unique_ptr<CWallet> wallet_ptr{std::make_unique<CWallet>(node.chain.get(), "", CreateMockableWalletDatabase())};
+    CWallet& wallet{*wallet_ptr};
+    wallet.m_keypool_size = 1;
+    {
+        LOCK(wallet.cs_wallet);
+        wallet.SetLastBlockProcessed(chainstate.m_chain.Height(), chainstate.m_chain.Tip()->GetBlockHash());
+    }
+
+    auto& legacy_data{*wallet.GetOrCreateLegacyDataSPKM()};
+
+    std::vector<CKey> keys;
+    LIMITED_WHILE(fuzzed_data_provider.ConsumeBool(), 30) {
+        const auto key{ConsumePrivateKey(fuzzed_data_provider)};
+        if (!key.IsValid()) return;
+        auto pub_key{key.GetPubKey()};
+        if (!pub_key.IsFullyValid()) return;
+        if (legacy_data.LoadKey(key, pub_key) && std::find(keys.begin(), keys.end(), key) == keys.end()) keys.push_back(key);
+    }
+
+    if (keys.empty()) return;
+
+    auto hd_key{PickValue(fuzzed_data_provider, keys)};
+    bool add_hd_chain{fuzzed_data_provider.ConsumeBool()};
+    CHDChain hd_chain;
+    if (add_hd_chain) {
+        hd_chain.nVersion = fuzzed_data_provider.ConsumeBool() ? CHDChain::VERSION_HD_CHAIN_SPLIT : CHDChain::VERSION_HD_BASE;
+        hd_chain.seed_id = hd_key.GetPubKey().GetID();
+        legacy_data.LoadHDChain(hd_chain);
+    }
+
+    int script_count{0};
+    bool good_data{true};
+    LIMITED_WHILE(good_data && fuzzed_data_provider.ConsumeBool(), 30) {
+        CallOneOf(
+            fuzzed_data_provider,
+            [&] {
+                CKey private_key{ConsumePrivateKey(fuzzed_data_provider)};
+                if (!private_key.IsValid()) return;
+                const auto& dest{GetDestinationForKey(private_key.GetPubKey(), OutputType::LEGACY)};
+                (void)legacy_data.LoadWatchOnly(GetScriptForDestination(dest));
+            },
+            [&] {
+                CScript script;
+                auto key{PickValue(fuzzed_data_provider, keys)};
+                auto pub_key{key.GetPubKey()};
+                bool key_hash{false};
+                if (fuzzed_data_provider.ConsumeBool()) {
+                    script = GetScriptForDestination(CTxDestination{PKHash(pub_key)});
+                } else {
+                    key_hash = true;
+                    script = GetScriptForDestination(WitnessV0KeyHash(pub_key));
+                }
+                if (legacy_data.AddCScript(script) && !key_hash) script_count++;
+            },
+            [&] {
+                auto key{PickValue(fuzzed_data_provider, keys)};
+                const auto num_keys{fuzzed_data_provider.ConsumeIntegralInRange<size_t>(1, MAX_PUBKEYS_PER_MULTISIG)};
+                std::vector<CPubKey> pubkeys;
+                size_t known_keys{0};
+                for (size_t i = 0; i < num_keys; i++) {
+                    if (fuzzed_data_provider.ConsumeBool()) {
+                        known_keys++;
+                        assert(!keys.empty());
+                        pubkeys.emplace_back(key.GetPubKey());
+                    } else {
+                        CKey private_key{ConsumePrivateKey(fuzzed_data_provider)};
+                        if (!private_key.IsValid()) return;
+                        pubkeys.emplace_back(private_key.GetPubKey());
+                        if (std::find(keys.begin(), keys.end(), private_key) != keys.end()) known_keys++;
+                    }
+                }
+                if (pubkeys.size() < num_keys) return;
+                const auto multisig_script{GetScriptForMultisig(num_keys, pubkeys)};
+                if (legacy_data.AddCScript(multisig_script) && known_keys == num_keys) script_count++;
+            }
+        );
+    }
+
+    std::optional<MigrationData> res{legacy_data.MigrateToDescriptor()};
+    assert(res->desc_spkms.size() == (keys.size() + size_t{add_hd_chain} + script_count)); 
+    std::vector<uint256> ids;
+    for (auto& spkm : res->desc_spkms) {
+        // Duplicate descriptors should not be created during migration.
+        assert(std::find(ids.begin(), ids.end(), spkm->GetID()) == ids.end());
+        ids.push_back(spkm->GetID());
+    }
+
+    if (add_hd_chain) {
+        CExtKey master_key;
+        master_key.SetSeed(hd_key);
+        assert(res->master_key == master_key);
+    }
+}
+
 } // namespace
 } // namespace wallet