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 CoinsViewEmpty 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 void BatchWrite(CoinsViewCacheCursor& cursor, const uint256&) final 157 { 158 for (auto it{cursor.Begin()}; it != cursor.End(); it = cursor.NextAndMaybeErase(*it)) { 159 if (it->second.IsDirty()) { 160 if (it->second.coin.IsSpent()) { 161 m_data.erase(it->first); 162 } else { 163 if (cursor.WillErase(*it)) { 164 m_data[it->first] = std::move(it->second.coin); 165 } else { 166 m_data[it->first] = it->second.coin; 167 } 168 } 169 } else { 170 /* For non-dirty entries being written, compare them with what we have. */ 171 auto it2 = m_data.find(it->first); 172 if (it->second.coin.IsSpent()) { 173 assert(it2 == m_data.end()); 174 } else { 175 assert(it2 != m_data.end()); 176 assert(it->second.coin.out == it2->second.out); 177 assert(it->second.coin.fCoinBase == it2->second.fCoinBase); 178 assert(it->second.coin.nHeight == it2->second.nHeight); 179 } 180 } 181 } 182 } 183 }; 184 185 } // namespace 186 187 FUZZ_TARGET(coinscache_sim) 188 { 189 /** Precomputed COutPoint and CCoins values. */ 190 static const PrecomputedData data; 191 192 /** Dummy coinsview instance (base of the hierarchy). */ 193 CoinsViewBottom bottom; 194 /** Real CCoinsViewCache objects. */ 195 std::vector<std::unique_ptr<CCoinsViewCache>> caches; 196 /** Simulated cache data (sim_caches[0] matches bottom, sim_caches[i+1] matches caches[i]). */ 197 CacheLevel sim_caches[MAX_CACHES + 1]; 198 /** Current height in the simulation. */ 199 uint32_t current_height = 1U; 200 201 // Initialize bottom simulated cache. 202 sim_caches[0].Wipe(); 203 204 /** Helper lookup function in the simulated cache stack. */ 205 auto lookup = [&](uint32_t outpointidx, int sim_idx = -1) -> std::optional<std::pair<coinidx_type, uint32_t>> { 206 uint32_t cache_idx = sim_idx == -1 ? caches.size() : sim_idx; 207 while (true) { 208 const auto& entry = sim_caches[cache_idx].entry[outpointidx]; 209 if (entry.entrytype == EntryType::UNSPENT) { 210 return {{entry.coinidx, entry.height}}; 211 } else if (entry.entrytype == EntryType::SPENT) { 212 return std::nullopt; 213 }; 214 if (cache_idx == 0) break; 215 --cache_idx; 216 } 217 return std::nullopt; 218 }; 219 220 /** Flush changes in top cache to the one below. */ 221 auto flush = [&]() { 222 assert(caches.size() >= 1); 223 auto& cache = sim_caches[caches.size()]; 224 auto& prev_cache = sim_caches[caches.size() - 1]; 225 for (uint32_t outpointidx = 0; outpointidx < NUM_OUTPOINTS; ++outpointidx) { 226 if (cache.entry[outpointidx].entrytype != EntryType::NONE) { 227 prev_cache.entry[outpointidx] = cache.entry[outpointidx]; 228 cache.entry[outpointidx].entrytype = EntryType::NONE; 229 } 230 } 231 }; 232 233 // Main simulation loop: read commands from the fuzzer input, and apply them 234 // to both the real cache stack and the simulation. 235 FuzzedDataProvider provider(buffer.data(), buffer.size()); 236 LIMITED_WHILE(provider.remaining_bytes(), 10000) { 237 // Every operation (except "Change height") moves current height forward, 238 // so it functions as a kind of epoch, making ~all UTXOs unique. 239 ++current_height; 240 // Make sure there is always at least one CCoinsViewCache. 241 if (caches.empty()) { 242 caches.emplace_back(new CCoinsViewCache(&bottom, /*deterministic=*/true)); 243 sim_caches[caches.size()].Wipe(); 244 } 245 246 // Execute command. 247 CallOneOf( 248 provider, 249 250 [&]() { // PeekCoin/GetCoin 251 uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1); 252 // Look up in simulation data. 253 auto sim = lookup(outpointidx); 254 // Look up in real caches. 255 auto realcoin = provider.ConsumeBool() ? 256 caches.back()->PeekCoin(data.outpoints[outpointidx]) : 257 caches.back()->GetCoin(data.outpoints[outpointidx]); 258 // Compare results. 259 if (!sim.has_value()) { 260 assert(!realcoin); 261 } else { 262 assert(realcoin && !realcoin->IsSpent()); 263 const auto& simcoin = data.coins[sim->first]; 264 assert(realcoin->out == simcoin.out); 265 assert(realcoin->fCoinBase == simcoin.fCoinBase); 266 assert(realcoin->nHeight == sim->second); 267 } 268 }, 269 270 [&]() { // HaveCoin 271 uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1); 272 // Look up in simulation data. 273 auto sim = lookup(outpointidx); 274 // Look up in real caches. 275 auto real = caches.back()->HaveCoin(data.outpoints[outpointidx]); 276 // Compare results. 277 assert(sim.has_value() == real); 278 }, 279 280 [&]() { // HaveCoinInCache 281 uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1); 282 // Invoke on real cache (there is no equivalent in simulation, so nothing to compare result with). 283 (void)caches.back()->HaveCoinInCache(data.outpoints[outpointidx]); 284 }, 285 286 [&]() { // AccessCoin 287 uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1); 288 // Look up in simulation data. 289 auto sim = lookup(outpointidx); 290 // Look up in real caches. 291 const auto& realcoin = caches.back()->AccessCoin(data.outpoints[outpointidx]); 292 // Compare results. 293 if (!sim.has_value()) { 294 assert(realcoin.IsSpent()); 295 } else { 296 assert(!realcoin.IsSpent()); 297 const auto& simcoin = data.coins[sim->first]; 298 assert(simcoin.out == realcoin.out); 299 assert(simcoin.fCoinBase == realcoin.fCoinBase); 300 assert(realcoin.nHeight == sim->second); 301 } 302 }, 303 304 [&]() { // AddCoin (only possible_overwrite if necessary) 305 uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1); 306 uint32_t coinidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_COINS - 1); 307 // Look up in simulation data (to know whether we must set possible_overwrite or not). 308 auto sim = lookup(outpointidx); 309 // Invoke on real caches. 310 Coin coin = data.coins[coinidx]; 311 coin.nHeight = current_height; 312 caches.back()->AddCoin(data.outpoints[outpointidx], std::move(coin), sim.has_value()); 313 // Apply to simulation data. 314 auto& entry = sim_caches[caches.size()].entry[outpointidx]; 315 entry.entrytype = EntryType::UNSPENT; 316 entry.coinidx = coinidx; 317 entry.height = current_height; 318 }, 319 320 [&]() { // AddCoin (always possible_overwrite) 321 uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1); 322 uint32_t coinidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_COINS - 1); 323 // Invoke on real caches. 324 Coin coin = data.coins[coinidx]; 325 coin.nHeight = current_height; 326 caches.back()->AddCoin(data.outpoints[outpointidx], std::move(coin), true); 327 // Apply to simulation data. 328 auto& entry = sim_caches[caches.size()].entry[outpointidx]; 329 entry.entrytype = EntryType::UNSPENT; 330 entry.coinidx = coinidx; 331 entry.height = current_height; 332 }, 333 334 [&]() { // SpendCoin (moveto = nullptr) 335 uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1); 336 // Invoke on real caches. 337 caches.back()->SpendCoin(data.outpoints[outpointidx], nullptr); 338 // Apply to simulation data. 339 sim_caches[caches.size()].entry[outpointidx].entrytype = EntryType::SPENT; 340 }, 341 342 [&]() { // SpendCoin (with moveto) 343 uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1); 344 // Look up in simulation data (to compare the returned *moveto with). 345 auto sim = lookup(outpointidx); 346 // Invoke on real caches. 347 Coin realcoin; 348 caches.back()->SpendCoin(data.outpoints[outpointidx], &realcoin); 349 // Apply to simulation data. 350 sim_caches[caches.size()].entry[outpointidx].entrytype = EntryType::SPENT; 351 // Compare *moveto with the value expected based on simulation data. 352 if (!sim.has_value()) { 353 assert(realcoin.IsSpent()); 354 } else { 355 assert(!realcoin.IsSpent()); 356 const auto& simcoin = data.coins[sim->first]; 357 assert(simcoin.out == realcoin.out); 358 assert(simcoin.fCoinBase == realcoin.fCoinBase); 359 assert(realcoin.nHeight == sim->second); 360 } 361 }, 362 363 [&]() { // Uncache 364 uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1); 365 // Apply to real caches (there is no equivalent in our simulation). 366 caches.back()->Uncache(data.outpoints[outpointidx]); 367 }, 368 369 [&]() { // Add a cache level (if not already at the max). 370 if (caches.size() != MAX_CACHES) { 371 // Apply to real caches. 372 if (provider.ConsumeBool()) { 373 caches.emplace_back(new CCoinsViewCache(&*caches.back(), /*deterministic=*/true)); 374 } else { 375 caches.emplace_back(new CoinsViewOverlay(&*caches.back(), /*deterministic=*/true)); 376 } 377 // Apply to simulation data. 378 sim_caches[caches.size()].Wipe(); 379 } 380 }, 381 382 [&]() { // Remove a cache level. 383 // Apply to real caches (this reduces caches.size(), implicitly doing the same on the simulation data). 384 caches.back()->SanityCheck(); 385 caches.pop_back(); 386 }, 387 388 [&]() { // Flush. 389 // Apply to simulation data. 390 flush(); 391 // Apply to real caches. 392 caches.back()->Flush(/*reallocate_cache=*/provider.ConsumeBool()); 393 }, 394 395 [&]() { // Sync. 396 // Apply to simulation data (note that in our simulation, syncing and flushing is the same thing). 397 flush(); 398 // Apply to real caches. 399 caches.back()->Sync(); 400 }, 401 402 [&]() { // Reset. 403 sim_caches[caches.size()].Wipe(); 404 // Apply to real caches. 405 { 406 const auto reset_guard{caches.back()->CreateResetGuard()}; 407 } 408 }, 409 410 [&]() { // GetCacheSize 411 (void)caches.back()->GetCacheSize(); 412 }, 413 414 [&]() { // DynamicMemoryUsage 415 (void)caches.back()->DynamicMemoryUsage(); 416 }, 417 418 [&]() { // Change height 419 current_height = provider.ConsumeIntegralInRange<uint32_t>(1, current_height - 1); 420 } 421 ); 422 } 423 424 // Sanity check all the remaining caches 425 for (const auto& cache : caches) { 426 cache->SanityCheck(); 427 } 428 429 // Full comparison between caches and simulation data, from bottom to top, 430 // as AccessCoin on a higher cache may affect caches below it. 431 for (unsigned sim_idx = 1; sim_idx <= caches.size(); ++sim_idx) { 432 auto& cache = *caches[sim_idx - 1]; 433 size_t cache_size = 0; 434 435 for (uint32_t outpointidx = 0; outpointidx < NUM_OUTPOINTS; ++outpointidx) { 436 cache_size += cache.HaveCoinInCache(data.outpoints[outpointidx]); 437 const auto& real = cache.AccessCoin(data.outpoints[outpointidx]); 438 auto sim = lookup(outpointidx, sim_idx); 439 if (!sim.has_value()) { 440 assert(real.IsSpent()); 441 } else { 442 assert(!real.IsSpent()); 443 assert(real.out == data.coins[sim->first].out); 444 assert(real.fCoinBase == data.coins[sim->first].fCoinBase); 445 assert(real.nHeight == sim->second); 446 } 447 } 448 449 // HaveCoinInCache ignores spent coins, so GetCacheSize() may exceed it. */ 450 assert(cache.GetCacheSize() >= cache_size); 451 } 452 453 // Compare the bottom coinsview (not a CCoinsViewCache) with sim_cache[0]. 454 for (uint32_t outpointidx = 0; outpointidx < NUM_OUTPOINTS; ++outpointidx) { 455 auto realcoin = bottom.GetCoin(data.outpoints[outpointidx]); 456 auto sim = lookup(outpointidx, 0); 457 if (!sim.has_value()) { 458 assert(!realcoin); 459 } else { 460 assert(realcoin && !realcoin->IsSpent()); 461 assert(realcoin->out == data.coins[sim->first].out); 462 assert(realcoin->fCoinBase == data.coins[sim->first].fCoinBase); 463 assert(realcoin->nHeight == sim->second); 464 } 465 } 466 }