coinscache_sim.cpp
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 #include <coins.h> 6 #include <crypto/sha256.h> 7 #include <primitives/transaction.h> 8 #include <test/fuzz/FuzzedDataProvider.h> 9 #include <test/fuzz/fuzz.h> 10 #include <test/fuzz/util.h> 11 12 #include <cassert> 13 #include <cstdint> 14 #include <memory> 15 #include <optional> 16 #include <vector> 17 18 namespace { 19 20 /** Number of distinct COutPoint values used in this test. */ 21 constexpr uint32_t NUM_OUTPOINTS = 256; 22 /** Number of distinct Coin values used in this test (ignoring nHeight). */ 23 constexpr uint32_t NUM_COINS = 256; 24 /** Maximum number CCoinsViewCache objects used in this test. */ 25 constexpr uint32_t MAX_CACHES = 4; 26 /** Data type large enough to hold NUM_COINS-1. */ 27 using coinidx_type = uint8_t; 28 29 struct PrecomputedData 30 { 31 //! Randomly generated COutPoint values. 32 COutPoint outpoints[NUM_OUTPOINTS]; 33 34 //! Randomly generated Coin values. 35 Coin coins[NUM_COINS]; 36 37 PrecomputedData() 38 { 39 static const uint8_t PREFIX_O[1] = {'o'}; /** Hash prefix for outpoint hashes. */ 40 static const uint8_t PREFIX_S[1] = {'s'}; /** Hash prefix for coins scriptPubKeys. */ 41 static const uint8_t PREFIX_M[1] = {'m'}; /** Hash prefix for coins nValue/fCoinBase. */ 42 43 for (uint32_t i = 0; i < NUM_OUTPOINTS; ++i) { 44 uint32_t idx = (i * 1200U) >> 12; /* Map 3 or 4 entries to same txid. */ 45 const uint8_t ser[4] = {uint8_t(idx), uint8_t(idx >> 8), uint8_t(idx >> 16), uint8_t(idx >> 24)}; 46 uint256 txid; 47 CSHA256().Write(PREFIX_O, 1).Write(ser, sizeof(ser)).Finalize(txid.begin()); 48 outpoints[i].hash = Txid::FromUint256(txid); 49 outpoints[i].n = i; 50 } 51 52 for (uint32_t i = 0; i < NUM_COINS; ++i) { 53 const uint8_t ser[4] = {uint8_t(i), uint8_t(i >> 8), uint8_t(i >> 16), uint8_t(i >> 24)}; 54 uint256 hash; 55 CSHA256().Write(PREFIX_S, 1).Write(ser, sizeof(ser)).Finalize(hash.begin()); 56 /* Convert hash to scriptPubkeys (of different lengths, so SanityCheck's cached memory 57 * usage check has a chance to detect mismatches). */ 58 switch (i % 5U) { 59 case 0: /* P2PKH */ 60 coins[i].out.scriptPubKey.resize(25); 61 coins[i].out.scriptPubKey[0] = OP_DUP; 62 coins[i].out.scriptPubKey[1] = OP_HASH160; 63 coins[i].out.scriptPubKey[2] = 20; 64 std::copy(hash.begin(), hash.begin() + 20, coins[i].out.scriptPubKey.begin() + 3); 65 coins[i].out.scriptPubKey[23] = OP_EQUALVERIFY; 66 coins[i].out.scriptPubKey[24] = OP_CHECKSIG; 67 break; 68 case 1: /* P2SH */ 69 coins[i].out.scriptPubKey.resize(23); 70 coins[i].out.scriptPubKey[0] = OP_HASH160; 71 coins[i].out.scriptPubKey[1] = 20; 72 std::copy(hash.begin(), hash.begin() + 20, coins[i].out.scriptPubKey.begin() + 2); 73 coins[i].out.scriptPubKey[12] = OP_EQUAL; 74 break; 75 case 2: /* P2WPKH */ 76 coins[i].out.scriptPubKey.resize(22); 77 coins[i].out.scriptPubKey[0] = OP_0; 78 coins[i].out.scriptPubKey[1] = 20; 79 std::copy(hash.begin(), hash.begin() + 20, coins[i].out.scriptPubKey.begin() + 2); 80 break; 81 case 3: /* P2WSH */ 82 coins[i].out.scriptPubKey.resize(34); 83 coins[i].out.scriptPubKey[0] = OP_0; 84 coins[i].out.scriptPubKey[1] = 32; 85 std::copy(hash.begin(), hash.begin() + 32, coins[i].out.scriptPubKey.begin() + 2); 86 break; 87 case 4: /* P2TR */ 88 coins[i].out.scriptPubKey.resize(34); 89 coins[i].out.scriptPubKey[0] = OP_1; 90 coins[i].out.scriptPubKey[1] = 32; 91 std::copy(hash.begin(), hash.begin() + 32, coins[i].out.scriptPubKey.begin() + 2); 92 break; 93 } 94 /* Hash again to construct nValue and fCoinBase. */ 95 CSHA256().Write(PREFIX_M, 1).Write(ser, sizeof(ser)).Finalize(hash.begin()); 96 coins[i].out.nValue = CAmount(hash.GetUint64(0) % MAX_MONEY); 97 coins[i].fCoinBase = (hash.GetUint64(1) & 7) == 0; 98 coins[i].nHeight = 0; /* Real nHeight used in simulation is set dynamically. */ 99 } 100 } 101 }; 102 103 enum class EntryType : uint8_t 104 { 105 /* This entry in the cache does not exist (so we'd have to look in the parent cache). */ 106 NONE, 107 108 /* This entry in the cache corresponds to an unspent coin. */ 109 UNSPENT, 110 111 /* This entry in the cache corresponds to a spent coin. */ 112 SPENT, 113 }; 114 115 struct CacheEntry 116 { 117 /* Type of entry. */ 118 EntryType entrytype; 119 120 /* Index in the coins array this entry corresponds to (only if entrytype == UNSPENT). */ 121 coinidx_type coinidx; 122 123 /* nHeight value for this entry (so the coins[coinidx].nHeight value is ignored; only if entrytype == UNSPENT). */ 124 uint32_t height; 125 }; 126 127 struct CacheLevel 128 { 129 CacheEntry entry[NUM_OUTPOINTS]; 130 131 void Wipe() { 132 for (uint32_t i = 0; i < NUM_OUTPOINTS; ++i) { 133 entry[i].entrytype = EntryType::NONE; 134 } 135 } 136 }; 137 138 /** Class for the base of the hierarchy (roughly simulating a memory-backed CCoinsViewDB). 139 * 140 * The initial state consists of the empty UTXO set. 141 */ 142 class CoinsViewBottom final : public CCoinsView 143 { 144 std::map<COutPoint, Coin> m_data; 145 146 public: 147 std::optional<Coin> GetCoin(const COutPoint& outpoint) const final 148 { 149 if (auto it{m_data.find(outpoint)}; it != m_data.end()) { 150 assert(!it->second.IsSpent()); 151 return it->second; 152 } 153 return std::nullopt; 154 } 155 156 uint256 GetBestBlock() const final { return {}; } 157 std::vector<uint256> GetHeadBlocks() const final { return {}; } 158 std::unique_ptr<CCoinsViewCursor> Cursor() const final { return {}; } 159 size_t EstimateSize() const final { return m_data.size(); } 160 161 void BatchWrite(CoinsViewCacheCursor& cursor, const uint256&) final 162 { 163 for (auto it{cursor.Begin()}; it != cursor.End(); it = cursor.NextAndMaybeErase(*it)) { 164 if (it->second.IsDirty()) { 165 if (it->second.coin.IsSpent()) { 166 m_data.erase(it->first); 167 } else { 168 if (cursor.WillErase(*it)) { 169 m_data[it->first] = std::move(it->second.coin); 170 } else { 171 m_data[it->first] = it->second.coin; 172 } 173 } 174 } else { 175 /* For non-dirty entries being written, compare them with what we have. */ 176 auto it2 = m_data.find(it->first); 177 if (it->second.coin.IsSpent()) { 178 assert(it2 == m_data.end()); 179 } else { 180 assert(it2 != m_data.end()); 181 assert(it->second.coin.out == it2->second.out); 182 assert(it->second.coin.fCoinBase == it2->second.fCoinBase); 183 assert(it->second.coin.nHeight == it2->second.nHeight); 184 } 185 } 186 } 187 } 188 }; 189 190 } // namespace 191 192 FUZZ_TARGET(coinscache_sim) 193 { 194 /** Precomputed COutPoint and CCoins values. */ 195 static const PrecomputedData data; 196 197 /** Dummy coinsview instance (base of the hierarchy). */ 198 CoinsViewBottom bottom; 199 /** Real CCoinsViewCache objects. */ 200 std::vector<std::unique_ptr<CCoinsViewCache>> caches; 201 /** Simulated cache data (sim_caches[0] matches bottom, sim_caches[i+1] matches caches[i]). */ 202 CacheLevel sim_caches[MAX_CACHES + 1]; 203 /** Current height in the simulation. */ 204 uint32_t current_height = 1U; 205 206 // Initialize bottom simulated cache. 207 sim_caches[0].Wipe(); 208 209 /** Helper lookup function in the simulated cache stack. */ 210 auto lookup = [&](uint32_t outpointidx, int sim_idx = -1) -> std::optional<std::pair<coinidx_type, uint32_t>> { 211 uint32_t cache_idx = sim_idx == -1 ? caches.size() : sim_idx; 212 while (true) { 213 const auto& entry = sim_caches[cache_idx].entry[outpointidx]; 214 if (entry.entrytype == EntryType::UNSPENT) { 215 return {{entry.coinidx, entry.height}}; 216 } else if (entry.entrytype == EntryType::SPENT) { 217 return std::nullopt; 218 }; 219 if (cache_idx == 0) break; 220 --cache_idx; 221 } 222 return std::nullopt; 223 }; 224 225 /** Flush changes in top cache to the one below. */ 226 auto flush = [&]() { 227 assert(caches.size() >= 1); 228 auto& cache = sim_caches[caches.size()]; 229 auto& prev_cache = sim_caches[caches.size() - 1]; 230 for (uint32_t outpointidx = 0; outpointidx < NUM_OUTPOINTS; ++outpointidx) { 231 if (cache.entry[outpointidx].entrytype != EntryType::NONE) { 232 prev_cache.entry[outpointidx] = cache.entry[outpointidx]; 233 cache.entry[outpointidx].entrytype = EntryType::NONE; 234 } 235 } 236 }; 237 238 // Main simulation loop: read commands from the fuzzer input, and apply them 239 // to both the real cache stack and the simulation. 240 FuzzedDataProvider provider(buffer.data(), buffer.size()); 241 LIMITED_WHILE(provider.remaining_bytes(), 10000) { 242 // Every operation (except "Change height") moves current height forward, 243 // so it functions as a kind of epoch, making ~all UTXOs unique. 244 ++current_height; 245 // Make sure there is always at least one CCoinsViewCache. 246 if (caches.empty()) { 247 caches.emplace_back(new CCoinsViewCache(&bottom, /*deterministic=*/true)); 248 sim_caches[caches.size()].Wipe(); 249 } 250 251 // Execute command. 252 CallOneOf( 253 provider, 254 255 [&]() { // GetCoin 256 uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1); 257 // Look up in simulation data. 258 auto sim = lookup(outpointidx); 259 // Look up in real caches. 260 auto realcoin = provider.ConsumeBool() ? 261 caches.back()->PeekCoin(data.outpoints[outpointidx]) : 262 caches.back()->GetCoin(data.outpoints[outpointidx]); 263 // Compare results. 264 if (!sim.has_value()) { 265 assert(!realcoin); 266 } else { 267 assert(realcoin && !realcoin->IsSpent()); 268 const auto& simcoin = data.coins[sim->first]; 269 assert(realcoin->out == simcoin.out); 270 assert(realcoin->fCoinBase == simcoin.fCoinBase); 271 assert(realcoin->nHeight == sim->second); 272 } 273 }, 274 275 [&]() { // HaveCoin 276 uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1); 277 // Look up in simulation data. 278 auto sim = lookup(outpointidx); 279 // Look up in real caches. 280 auto real = caches.back()->HaveCoin(data.outpoints[outpointidx]); 281 // Compare results. 282 assert(sim.has_value() == real); 283 }, 284 285 [&]() { // HaveCoinInCache 286 uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1); 287 // Invoke on real cache (there is no equivalent in simulation, so nothing to compare result with). 288 (void)caches.back()->HaveCoinInCache(data.outpoints[outpointidx]); 289 }, 290 291 [&]() { // AccessCoin 292 uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1); 293 // Look up in simulation data. 294 auto sim = lookup(outpointidx); 295 // Look up in real caches. 296 const auto& realcoin = caches.back()->AccessCoin(data.outpoints[outpointidx]); 297 // Compare results. 298 if (!sim.has_value()) { 299 assert(realcoin.IsSpent()); 300 } else { 301 assert(!realcoin.IsSpent()); 302 const auto& simcoin = data.coins[sim->first]; 303 assert(simcoin.out == realcoin.out); 304 assert(simcoin.fCoinBase == realcoin.fCoinBase); 305 assert(realcoin.nHeight == sim->second); 306 } 307 }, 308 309 [&]() { // AddCoin (only possible_overwrite if necessary) 310 uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1); 311 uint32_t coinidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_COINS - 1); 312 // Look up in simulation data (to know whether we must set possible_overwrite or not). 313 auto sim = lookup(outpointidx); 314 // Invoke on real caches. 315 Coin coin = data.coins[coinidx]; 316 coin.nHeight = current_height; 317 caches.back()->AddCoin(data.outpoints[outpointidx], std::move(coin), sim.has_value()); 318 // Apply to simulation data. 319 auto& entry = sim_caches[caches.size()].entry[outpointidx]; 320 entry.entrytype = EntryType::UNSPENT; 321 entry.coinidx = coinidx; 322 entry.height = current_height; 323 }, 324 325 [&]() { // AddCoin (always possible_overwrite) 326 uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1); 327 uint32_t coinidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_COINS - 1); 328 // Invoke on real caches. 329 Coin coin = data.coins[coinidx]; 330 coin.nHeight = current_height; 331 caches.back()->AddCoin(data.outpoints[outpointidx], std::move(coin), true); 332 // Apply to simulation data. 333 auto& entry = sim_caches[caches.size()].entry[outpointidx]; 334 entry.entrytype = EntryType::UNSPENT; 335 entry.coinidx = coinidx; 336 entry.height = current_height; 337 }, 338 339 [&]() { // SpendCoin (moveto = nullptr) 340 uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1); 341 // Invoke on real caches. 342 caches.back()->SpendCoin(data.outpoints[outpointidx], nullptr); 343 // Apply to simulation data. 344 sim_caches[caches.size()].entry[outpointidx].entrytype = EntryType::SPENT; 345 }, 346 347 [&]() { // SpendCoin (with moveto) 348 uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1); 349 // Look up in simulation data (to compare the returned *moveto with). 350 auto sim = lookup(outpointidx); 351 // Invoke on real caches. 352 Coin realcoin; 353 caches.back()->SpendCoin(data.outpoints[outpointidx], &realcoin); 354 // Apply to simulation data. 355 sim_caches[caches.size()].entry[outpointidx].entrytype = EntryType::SPENT; 356 // Compare *moveto with the value expected based on simulation data. 357 if (!sim.has_value()) { 358 assert(realcoin.IsSpent()); 359 } else { 360 assert(!realcoin.IsSpent()); 361 const auto& simcoin = data.coins[sim->first]; 362 assert(simcoin.out == realcoin.out); 363 assert(simcoin.fCoinBase == realcoin.fCoinBase); 364 assert(realcoin.nHeight == sim->second); 365 } 366 }, 367 368 [&]() { // Uncache 369 uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1); 370 // Apply to real caches (there is no equivalent in our simulation). 371 caches.back()->Uncache(data.outpoints[outpointidx]); 372 }, 373 374 [&]() { // Add a cache level (if not already at the max). 375 if (caches.size() != MAX_CACHES) { 376 // Apply to real caches. 377 if (provider.ConsumeBool()) { 378 caches.emplace_back(new CCoinsViewCache(&*caches.back(), /*deterministic=*/true)); 379 } else { 380 caches.emplace_back(new CoinsViewOverlay(&*caches.back(), /*deterministic=*/true)); 381 } 382 // Apply to simulation data. 383 sim_caches[caches.size()].Wipe(); 384 } 385 }, 386 387 [&]() { // Remove a cache level. 388 // Apply to real caches (this reduces caches.size(), implicitly doing the same on the simulation data). 389 caches.back()->SanityCheck(); 390 caches.pop_back(); 391 }, 392 393 [&]() { // Flush. 394 // Apply to simulation data. 395 flush(); 396 // Apply to real caches. 397 caches.back()->Flush(/*reallocate_cache=*/provider.ConsumeBool()); 398 }, 399 400 [&]() { // Sync. 401 // Apply to simulation data (note that in our simulation, syncing and flushing is the same thing). 402 flush(); 403 // Apply to real caches. 404 caches.back()->Sync(); 405 }, 406 407 [&]() { // Reset. 408 sim_caches[caches.size()].Wipe(); 409 // Apply to real caches. 410 { 411 const auto reset_guard{caches.back()->CreateResetGuard()}; 412 } 413 }, 414 415 [&]() { // GetCacheSize 416 (void)caches.back()->GetCacheSize(); 417 }, 418 419 [&]() { // DynamicMemoryUsage 420 (void)caches.back()->DynamicMemoryUsage(); 421 }, 422 423 [&]() { // Change height 424 current_height = provider.ConsumeIntegralInRange<uint32_t>(1, current_height - 1); 425 } 426 ); 427 } 428 429 // Sanity check all the remaining caches 430 for (const auto& cache : caches) { 431 cache->SanityCheck(); 432 } 433 434 // Full comparison between caches and simulation data, from bottom to top, 435 // as AccessCoin on a higher cache may affect caches below it. 436 for (unsigned sim_idx = 1; sim_idx <= caches.size(); ++sim_idx) { 437 auto& cache = *caches[sim_idx - 1]; 438 size_t cache_size = 0; 439 440 for (uint32_t outpointidx = 0; outpointidx < NUM_OUTPOINTS; ++outpointidx) { 441 cache_size += cache.HaveCoinInCache(data.outpoints[outpointidx]); 442 const auto& real = cache.AccessCoin(data.outpoints[outpointidx]); 443 auto sim = lookup(outpointidx, sim_idx); 444 if (!sim.has_value()) { 445 assert(real.IsSpent()); 446 } else { 447 assert(!real.IsSpent()); 448 assert(real.out == data.coins[sim->first].out); 449 assert(real.fCoinBase == data.coins[sim->first].fCoinBase); 450 assert(real.nHeight == sim->second); 451 } 452 } 453 454 // HaveCoinInCache ignores spent coins, so GetCacheSize() may exceed it. */ 455 assert(cache.GetCacheSize() >= cache_size); 456 } 457 458 // Compare the bottom coinsview (not a CCoinsViewCache) with sim_cache[0]. 459 for (uint32_t outpointidx = 0; outpointidx < NUM_OUTPOINTS; ++outpointidx) { 460 auto realcoin = bottom.GetCoin(data.outpoints[outpointidx]); 461 auto sim = lookup(outpointidx, 0); 462 if (!sim.has_value()) { 463 assert(!realcoin); 464 } else { 465 assert(realcoin && !realcoin->IsSpent()); 466 assert(realcoin->out == data.coins[sim->first].out); 467 assert(realcoin->fCoinBase == data.coins[sim->first].fCoinBase); 468 assert(realcoin->nHeight == sim->second); 469 } 470 } 471 }