coinscache_sim.cpp
1 // Copyright (c) 2023 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/fuzz.h> 9 #include <test/fuzz/FuzzedDataProvider.h> 10 #include <test/fuzz/util.h> 11 12 #include <assert.h> 13 #include <optional> 14 #include <memory> 15 #include <stdint.h> 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 * Coins whose output index is 4 (mod 5) have GetCoin() always succeed after being spent. 142 * This exercises code paths with spent, non-DIRTY cache entries. 143 */ 144 class CoinsViewBottom final : public CCoinsView 145 { 146 std::map<COutPoint, Coin> m_data; 147 148 public: 149 std::optional<Coin> GetCoin(const COutPoint& outpoint) const final 150 { 151 // TODO GetCoin shouldn't return spent coins 152 if (auto it = m_data.find(outpoint); it != m_data.end()) return it->second; 153 return std::nullopt; 154 } 155 156 bool HaveCoin(const COutPoint& outpoint) const final 157 { 158 return m_data.count(outpoint); 159 } 160 161 uint256 GetBestBlock() const final { return {}; } 162 std::vector<uint256> GetHeadBlocks() const final { return {}; } 163 std::unique_ptr<CCoinsViewCursor> Cursor() const final { return {}; } 164 size_t EstimateSize() const final { return m_data.size(); } 165 166 bool BatchWrite(CoinsViewCacheCursor& cursor, const uint256&) final 167 { 168 for (auto it{cursor.Begin()}; it != cursor.End(); it = cursor.NextAndMaybeErase(*it)) { 169 if (it->second.IsDirty()) { 170 if (it->second.coin.IsSpent() && (it->first.n % 5) != 4) { 171 m_data.erase(it->first); 172 } else if (cursor.WillErase(*it)) { 173 m_data[it->first] = std::move(it->second.coin); 174 } else { 175 m_data[it->first] = it->second.coin; 176 } 177 } else { 178 /* For non-dirty entries being written, compare them with what we have. */ 179 auto it2 = m_data.find(it->first); 180 if (it->second.coin.IsSpent()) { 181 assert(it2 == m_data.end() || it2->second.IsSpent()); 182 } else { 183 assert(it2 != m_data.end()); 184 assert(it->second.coin.out == it2->second.out); 185 assert(it->second.coin.fCoinBase == it2->second.fCoinBase); 186 assert(it->second.coin.nHeight == it2->second.nHeight); 187 } 188 } 189 } 190 return true; 191 } 192 }; 193 194 } // namespace 195 196 FUZZ_TARGET(coinscache_sim) 197 { 198 /** Precomputed COutPoint and CCoins values. */ 199 static const PrecomputedData data; 200 201 /** Dummy coinsview instance (base of the hierarchy). */ 202 CoinsViewBottom bottom; 203 /** Real CCoinsViewCache objects. */ 204 std::vector<std::unique_ptr<CCoinsViewCache>> caches; 205 /** Simulated cache data (sim_caches[0] matches bottom, sim_caches[i+1] matches caches[i]). */ 206 CacheLevel sim_caches[MAX_CACHES + 1]; 207 /** Current height in the simulation. */ 208 uint32_t current_height = 1U; 209 210 // Initialize bottom simulated cache. 211 sim_caches[0].Wipe(); 212 213 /** Helper lookup function in the simulated cache stack. */ 214 auto lookup = [&](uint32_t outpointidx, int sim_idx = -1) -> std::optional<std::pair<coinidx_type, uint32_t>> { 215 uint32_t cache_idx = sim_idx == -1 ? caches.size() : sim_idx; 216 while (true) { 217 const auto& entry = sim_caches[cache_idx].entry[outpointidx]; 218 if (entry.entrytype == EntryType::UNSPENT) { 219 return {{entry.coinidx, entry.height}}; 220 } else if (entry.entrytype == EntryType::SPENT) { 221 return std::nullopt; 222 }; 223 if (cache_idx == 0) break; 224 --cache_idx; 225 } 226 return std::nullopt; 227 }; 228 229 /** Flush changes in top cache to the one below. */ 230 auto flush = [&]() { 231 assert(caches.size() >= 1); 232 auto& cache = sim_caches[caches.size()]; 233 auto& prev_cache = sim_caches[caches.size() - 1]; 234 for (uint32_t outpointidx = 0; outpointidx < NUM_OUTPOINTS; ++outpointidx) { 235 if (cache.entry[outpointidx].entrytype != EntryType::NONE) { 236 prev_cache.entry[outpointidx] = cache.entry[outpointidx]; 237 cache.entry[outpointidx].entrytype = EntryType::NONE; 238 } 239 } 240 }; 241 242 // Main simulation loop: read commands from the fuzzer input, and apply them 243 // to both the real cache stack and the simulation. 244 FuzzedDataProvider provider(buffer.data(), buffer.size()); 245 LIMITED_WHILE(provider.remaining_bytes(), 10000) { 246 // Every operation (except "Change height") moves current height forward, 247 // so it functions as a kind of epoch, making ~all UTXOs unique. 248 ++current_height; 249 // Make sure there is always at least one CCoinsViewCache. 250 if (caches.empty()) { 251 caches.emplace_back(new CCoinsViewCache(&bottom, /*deterministic=*/true)); 252 sim_caches[caches.size()].Wipe(); 253 } 254 255 // Execute command. 256 CallOneOf( 257 provider, 258 259 [&]() { // GetCoin 260 uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1); 261 // Look up in simulation data. 262 auto sim = lookup(outpointidx); 263 // Look up in real caches. 264 auto realcoin = caches.back()->GetCoin(data.outpoints[outpointidx]); 265 // Compare results. 266 if (!sim.has_value()) { 267 assert(!realcoin || realcoin->IsSpent()); 268 } else { 269 assert(realcoin && !realcoin->IsSpent()); 270 const auto& simcoin = data.coins[sim->first]; 271 assert(realcoin->out == simcoin.out); 272 assert(realcoin->fCoinBase == simcoin.fCoinBase); 273 assert(realcoin->nHeight == sim->second); 274 } 275 }, 276 277 [&]() { // HaveCoin 278 uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1); 279 // Look up in simulation data. 280 auto sim = lookup(outpointidx); 281 // Look up in real caches. 282 auto real = caches.back()->HaveCoin(data.outpoints[outpointidx]); 283 // Compare results. 284 assert(sim.has_value() == real); 285 }, 286 287 [&]() { // HaveCoinInCache 288 uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1); 289 // Invoke on real cache (there is no equivalent in simulation, so nothing to compare result with). 290 (void)caches.back()->HaveCoinInCache(data.outpoints[outpointidx]); 291 }, 292 293 [&]() { // AccessCoin 294 uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1); 295 // Look up in simulation data. 296 auto sim = lookup(outpointidx); 297 // Look up in real caches. 298 const auto& realcoin = caches.back()->AccessCoin(data.outpoints[outpointidx]); 299 // Compare results. 300 if (!sim.has_value()) { 301 assert(realcoin.IsSpent()); 302 } else { 303 assert(!realcoin.IsSpent()); 304 const auto& simcoin = data.coins[sim->first]; 305 assert(simcoin.out == realcoin.out); 306 assert(simcoin.fCoinBase == realcoin.fCoinBase); 307 assert(realcoin.nHeight == sim->second); 308 } 309 }, 310 311 [&]() { // AddCoin (only possible_overwrite if necessary) 312 uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1); 313 uint32_t coinidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_COINS - 1); 314 // Look up in simulation data (to know whether we must set possible_overwrite or not). 315 auto sim = lookup(outpointidx); 316 // Invoke on real caches. 317 Coin coin = data.coins[coinidx]; 318 coin.nHeight = current_height; 319 caches.back()->AddCoin(data.outpoints[outpointidx], std::move(coin), sim.has_value()); 320 // Apply to simulation data. 321 auto& entry = sim_caches[caches.size()].entry[outpointidx]; 322 entry.entrytype = EntryType::UNSPENT; 323 entry.coinidx = coinidx; 324 entry.height = current_height; 325 }, 326 327 [&]() { // AddCoin (always possible_overwrite) 328 uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1); 329 uint32_t coinidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_COINS - 1); 330 // Invoke on real caches. 331 Coin coin = data.coins[coinidx]; 332 coin.nHeight = current_height; 333 caches.back()->AddCoin(data.outpoints[outpointidx], std::move(coin), true); 334 // Apply to simulation data. 335 auto& entry = sim_caches[caches.size()].entry[outpointidx]; 336 entry.entrytype = EntryType::UNSPENT; 337 entry.coinidx = coinidx; 338 entry.height = current_height; 339 }, 340 341 [&]() { // SpendCoin (moveto = nullptr) 342 uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1); 343 // Invoke on real caches. 344 caches.back()->SpendCoin(data.outpoints[outpointidx], nullptr); 345 // Apply to simulation data. 346 sim_caches[caches.size()].entry[outpointidx].entrytype = EntryType::SPENT; 347 }, 348 349 [&]() { // SpendCoin (with moveto) 350 uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1); 351 // Look up in simulation data (to compare the returned *moveto with). 352 auto sim = lookup(outpointidx); 353 // Invoke on real caches. 354 Coin realcoin; 355 caches.back()->SpendCoin(data.outpoints[outpointidx], &realcoin); 356 // Apply to simulation data. 357 sim_caches[caches.size()].entry[outpointidx].entrytype = EntryType::SPENT; 358 // Compare *moveto with the value expected based on simulation data. 359 if (!sim.has_value()) { 360 assert(realcoin.IsSpent()); 361 } else { 362 assert(!realcoin.IsSpent()); 363 const auto& simcoin = data.coins[sim->first]; 364 assert(simcoin.out == realcoin.out); 365 assert(simcoin.fCoinBase == realcoin.fCoinBase); 366 assert(realcoin.nHeight == sim->second); 367 } 368 }, 369 370 [&]() { // Uncache 371 uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1); 372 // Apply to real caches (there is no equivalent in our simulation). 373 caches.back()->Uncache(data.outpoints[outpointidx]); 374 }, 375 376 [&]() { // Add a cache level (if not already at the max). 377 if (caches.size() != MAX_CACHES) { 378 // Apply to real caches. 379 caches.emplace_back(new CCoinsViewCache(&*caches.back(), /*deterministic=*/true)); 380 // Apply to simulation data. 381 sim_caches[caches.size()].Wipe(); 382 } 383 }, 384 385 [&]() { // Remove a cache level. 386 // Apply to real caches (this reduces caches.size(), implicitly doing the same on the simulation data). 387 caches.back()->SanityCheck(); 388 caches.pop_back(); 389 }, 390 391 [&]() { // Flush. 392 // Apply to simulation data. 393 flush(); 394 // Apply to real caches. 395 caches.back()->Flush(); 396 }, 397 398 [&]() { // Sync. 399 // Apply to simulation data (note that in our simulation, syncing and flushing is the same thing). 400 flush(); 401 // Apply to real caches. 402 caches.back()->Sync(); 403 }, 404 405 [&]() { // Flush + ReallocateCache. 406 // Apply to simulation data. 407 flush(); 408 // Apply to real caches. 409 caches.back()->Flush(); 410 caches.back()->ReallocateCache(); 411 }, 412 413 [&]() { // GetCacheSize 414 (void)caches.back()->GetCacheSize(); 415 }, 416 417 [&]() { // DynamicMemoryUsage 418 (void)caches.back()->DynamicMemoryUsage(); 419 }, 420 421 [&]() { // Change height 422 current_height = provider.ConsumeIntegralInRange<uint32_t>(1, current_height - 1); 423 } 424 ); 425 } 426 427 // Sanity check all the remaining caches 428 for (const auto& cache : caches) { 429 cache->SanityCheck(); 430 } 431 432 // Full comparison between caches and simulation data, from bottom to top, 433 // as AccessCoin on a higher cache may affect caches below it. 434 for (unsigned sim_idx = 1; sim_idx <= caches.size(); ++sim_idx) { 435 auto& cache = *caches[sim_idx - 1]; 436 size_t cache_size = 0; 437 438 for (uint32_t outpointidx = 0; outpointidx < NUM_OUTPOINTS; ++outpointidx) { 439 cache_size += cache.HaveCoinInCache(data.outpoints[outpointidx]); 440 const auto& real = cache.AccessCoin(data.outpoints[outpointidx]); 441 auto sim = lookup(outpointidx, sim_idx); 442 if (!sim.has_value()) { 443 assert(real.IsSpent()); 444 } else { 445 assert(!real.IsSpent()); 446 assert(real.out == data.coins[sim->first].out); 447 assert(real.fCoinBase == data.coins[sim->first].fCoinBase); 448 assert(real.nHeight == sim->second); 449 } 450 } 451 452 // HaveCoinInCache ignores spent coins, so GetCacheSize() may exceed it. */ 453 assert(cache.GetCacheSize() >= cache_size); 454 } 455 456 // Compare the bottom coinsview (not a CCoinsViewCache) with sim_cache[0]. 457 for (uint32_t outpointidx = 0; outpointidx < NUM_OUTPOINTS; ++outpointidx) { 458 auto realcoin = bottom.GetCoin(data.outpoints[outpointidx]); 459 auto sim = lookup(outpointidx, 0); 460 if (!sim.has_value()) { 461 assert(!realcoin || realcoin->IsSpent()); 462 } else { 463 assert(realcoin && !realcoin->IsSpent()); 464 assert(realcoin->out == data.coins[sim->first].out); 465 assert(realcoin->fCoinBase == data.coins[sim->first].fCoinBase); 466 assert(realcoin->nHeight == sim->second); 467 } 468 } 469 }