Line data Source code
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 2 : constexpr uint32_t MAX_CACHES = 4;
26 : /** Data type large enough to hold NUM_COINS-1. */
27 : using coinidx_type = uint8_t;
28 :
29 0 : 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 0 : 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 0 : for (uint32_t i = 0; i < NUM_OUTPOINTS; ++i) {
44 0 : uint32_t idx = (i * 1200U) >> 12; /* Map 3 or 4 entries to same txid. */
45 0 : const uint8_t ser[4] = {uint8_t(idx), uint8_t(idx >> 8), uint8_t(idx >> 16), uint8_t(idx >> 24)};
46 0 : CSHA256().Write(PREFIX_O, 1).Write(ser, sizeof(ser)).Finalize(outpoints[i].hash.begin());
47 0 : outpoints[i].n = i;
48 0 : }
49 :
50 0 : for (uint32_t i = 0; i < NUM_COINS; ++i) {
51 0 : const uint8_t ser[4] = {uint8_t(i), uint8_t(i >> 8), uint8_t(i >> 16), uint8_t(i >> 24)};
52 0 : uint256 hash;
53 0 : CSHA256().Write(PREFIX_S, 1).Write(ser, sizeof(ser)).Finalize(hash.begin());
54 : /* Convert hash to scriptPubkeys (of different lengths, so SanityCheck's cached memory
55 : * usage check has a chance to detect mismatches). */
56 0 : switch (i % 5U) {
57 : case 0: /* P2PKH */
58 0 : coins[i].out.scriptPubKey.resize(25);
59 0 : coins[i].out.scriptPubKey[0] = OP_DUP;
60 0 : coins[i].out.scriptPubKey[1] = OP_HASH160;
61 0 : coins[i].out.scriptPubKey[2] = 20;
62 0 : std::copy(hash.begin(), hash.begin() + 20, coins[i].out.scriptPubKey.begin() + 3);
63 0 : coins[i].out.scriptPubKey[23] = OP_EQUALVERIFY;
64 0 : coins[i].out.scriptPubKey[24] = OP_CHECKSIG;
65 0 : break;
66 : case 1: /* P2SH */
67 0 : coins[i].out.scriptPubKey.resize(23);
68 0 : coins[i].out.scriptPubKey[0] = OP_HASH160;
69 0 : coins[i].out.scriptPubKey[1] = 20;
70 0 : std::copy(hash.begin(), hash.begin() + 20, coins[i].out.scriptPubKey.begin() + 2);
71 0 : coins[i].out.scriptPubKey[12] = OP_EQUAL;
72 0 : break;
73 : case 2: /* P2WPKH */
74 0 : coins[i].out.scriptPubKey.resize(22);
75 0 : coins[i].out.scriptPubKey[0] = OP_0;
76 0 : coins[i].out.scriptPubKey[1] = 20;
77 0 : std::copy(hash.begin(), hash.begin() + 20, coins[i].out.scriptPubKey.begin() + 2);
78 0 : break;
79 : case 3: /* P2WSH */
80 0 : coins[i].out.scriptPubKey.resize(34);
81 0 : coins[i].out.scriptPubKey[0] = OP_0;
82 0 : coins[i].out.scriptPubKey[1] = 32;
83 0 : std::copy(hash.begin(), hash.begin() + 32, coins[i].out.scriptPubKey.begin() + 2);
84 0 : break;
85 : case 4: /* P2TR */
86 0 : coins[i].out.scriptPubKey.resize(34);
87 0 : coins[i].out.scriptPubKey[0] = OP_1;
88 0 : coins[i].out.scriptPubKey[1] = 32;
89 0 : std::copy(hash.begin(), hash.begin() + 32, coins[i].out.scriptPubKey.begin() + 2);
90 0 : break;
91 : }
92 : /* Hash again to construct nValue and fCoinBase. */
93 0 : CSHA256().Write(PREFIX_M, 1).Write(ser, sizeof(ser)).Finalize(hash.begin());
94 0 : coins[i].out.nValue = CAmount(hash.GetUint64(0) % MAX_MONEY);
95 0 : coins[i].fCoinBase = (hash.GetUint64(1) & 7) == 0;
96 0 : coins[i].nHeight = 0; /* Real nHeight used in simulation is set dynamically. */
97 0 : }
98 0 : }
99 : };
100 :
101 : enum class EntryType : uint8_t
102 : {
103 : /* This entry in the cache does not exist (so we'd have to look in the parent cache). */
104 : NONE,
105 :
106 : /* This entry in the cache corresponds to an unspent coin. */
107 : UNSPENT,
108 :
109 : /* This entry in the cache corresponds to a spent coin. */
110 : SPENT,
111 : };
112 :
113 : struct CacheEntry
114 : {
115 : /* Type of entry. */
116 : EntryType entrytype;
117 :
118 : /* Index in the coins array this entry corresponds to (only if entrytype == UNSPENT). */
119 : coinidx_type coinidx;
120 :
121 : /* nHeight value for this entry (so the coins[coinidx].nHeight value is ignored; only if entrytype == UNSPENT). */
122 : uint32_t height;
123 : };
124 :
125 : struct CacheLevel
126 : {
127 : CacheEntry entry[NUM_OUTPOINTS];
128 :
129 0 : void Wipe() {
130 0 : for (uint32_t i = 0; i < NUM_OUTPOINTS; ++i) {
131 0 : entry[i].entrytype = EntryType::NONE;
132 0 : }
133 0 : }
134 : };
135 :
136 : /** Class for the base of the hierarchy (roughly simulating a memory-backed CCoinsViewDB).
137 : *
138 : * The initial state consists of the empty UTXO set, though coins whose output index
139 : * is 3 (mod 5) always have GetCoin() succeed (but returning an IsSpent() coin unless a UTXO
140 : * exists). Coins whose output index is 4 (mod 5) have GetCoin() always succeed after being spent.
141 : * This exercises code paths with spent, non-DIRTY cache entries.
142 : */
143 : class CoinsViewBottom final : public CCoinsView
144 : {
145 : std::map<COutPoint, Coin> m_data;
146 :
147 : public:
148 0 : bool GetCoin(const COutPoint& outpoint, Coin& coin) const final
149 : {
150 0 : auto it = m_data.find(outpoint);
151 0 : if (it == m_data.end()) {
152 0 : if ((outpoint.n % 5) == 3) {
153 0 : coin.Clear();
154 0 : return true;
155 : }
156 0 : return false;
157 : } else {
158 0 : coin = it->second;
159 0 : return true;
160 : }
161 0 : }
162 :
163 0 : bool HaveCoin(const COutPoint& outpoint) const final
164 : {
165 0 : return m_data.count(outpoint);
166 : }
167 :
168 0 : uint256 GetBestBlock() const final { return {}; }
169 0 : std::vector<uint256> GetHeadBlocks() const final { return {}; }
170 0 : std::unique_ptr<CCoinsViewCursor> Cursor() const final { return {}; }
171 0 : size_t EstimateSize() const final { return m_data.size(); }
172 :
173 0 : bool BatchWrite(CCoinsMap& data, const uint256&, bool erase) final
174 : {
175 0 : for (auto it = data.begin(); it != data.end(); it = erase ? data.erase(it) : std::next(it)) {
176 0 : if (it->second.flags & CCoinsCacheEntry::DIRTY) {
177 0 : if (it->second.coin.IsSpent() && (it->first.n % 5) != 4) {
178 0 : m_data.erase(it->first);
179 0 : } else if (erase) {
180 0 : m_data[it->first] = std::move(it->second.coin);
181 0 : } else {
182 0 : m_data[it->first] = it->second.coin;
183 : }
184 0 : } else {
185 : /* For non-dirty entries being written, compare them with what we have. */
186 0 : auto it2 = m_data.find(it->first);
187 0 : if (it->second.coin.IsSpent()) {
188 0 : assert(it2 == m_data.end() || it2->second.IsSpent());
189 0 : } else {
190 0 : assert(it2 != m_data.end());
191 0 : assert(it->second.coin.out == it2->second.out);
192 0 : assert(it->second.coin.fCoinBase == it2->second.fCoinBase);
193 0 : assert(it->second.coin.nHeight == it2->second.nHeight);
194 : }
195 : }
196 0 : }
197 0 : return true;
198 : }
199 : };
200 :
201 : } // namespace
202 :
203 4 : FUZZ_TARGET(coinscache_sim)
204 : {
205 : /** Precomputed COutPoint and CCoins values. */
206 0 : static const PrecomputedData data;
207 :
208 : /** Dummy coinsview instance (base of the hierarchy). */
209 0 : CoinsViewBottom bottom;
210 : /** Real CCoinsViewCache objects. */
211 0 : std::vector<std::unique_ptr<CCoinsViewCache>> caches;
212 : /** Simulated cache data (sim_caches[0] matches bottom, sim_caches[i+1] matches caches[i]). */
213 : CacheLevel sim_caches[MAX_CACHES + 1];
214 : /** Current height in the simulation. */
215 0 : uint32_t current_height = 1U;
216 :
217 : // Initialize bottom simulated cache.
218 0 : sim_caches[0].Wipe();
219 :
220 : /** Helper lookup function in the simulated cache stack. */
221 0 : auto lookup = [&](uint32_t outpointidx, int sim_idx = -1) -> std::optional<std::pair<coinidx_type, uint32_t>> {
222 0 : uint32_t cache_idx = sim_idx == -1 ? caches.size() : sim_idx;
223 0 : while (true) {
224 0 : const auto& entry = sim_caches[cache_idx].entry[outpointidx];
225 0 : if (entry.entrytype == EntryType::UNSPENT) {
226 0 : return {{entry.coinidx, entry.height}};
227 0 : } else if (entry.entrytype == EntryType::SPENT) {
228 0 : return std::nullopt;
229 : };
230 0 : if (cache_idx == 0) break;
231 0 : --cache_idx;
232 : }
233 0 : return std::nullopt;
234 0 : };
235 :
236 : /** Flush changes in top cache to the one below. */
237 0 : auto flush = [&]() {
238 0 : assert(caches.size() >= 1);
239 0 : auto& cache = sim_caches[caches.size()];
240 0 : auto& prev_cache = sim_caches[caches.size() - 1];
241 0 : for (uint32_t outpointidx = 0; outpointidx < NUM_OUTPOINTS; ++outpointidx) {
242 0 : if (cache.entry[outpointidx].entrytype != EntryType::NONE) {
243 0 : prev_cache.entry[outpointidx] = cache.entry[outpointidx];
244 0 : cache.entry[outpointidx].entrytype = EntryType::NONE;
245 0 : }
246 0 : }
247 0 : };
248 :
249 : // Main simulation loop: read commands from the fuzzer input, and apply them
250 : // to both the real cache stack and the simulation.
251 0 : FuzzedDataProvider provider(buffer.data(), buffer.size());
252 0 : LIMITED_WHILE(provider.remaining_bytes(), 10000) {
253 : // Every operation (except "Change height") moves current height forward,
254 : // so it functions as a kind of epoch, making ~all UTXOs unique.
255 0 : ++current_height;
256 : // Make sure there is always at least one CCoinsViewCache.
257 0 : if (caches.empty()) {
258 0 : caches.emplace_back(new CCoinsViewCache(&bottom, /*deterministic=*/true));
259 0 : sim_caches[caches.size()].Wipe();
260 0 : }
261 :
262 : // Execute command.
263 0 : CallOneOf(
264 : provider,
265 :
266 0 : [&]() { // GetCoin
267 0 : uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1);
268 : // Look up in simulation data.
269 0 : auto sim = lookup(outpointidx);
270 : // Look up in real caches.
271 0 : Coin realcoin;
272 0 : auto real = caches.back()->GetCoin(data.outpoints[outpointidx], realcoin);
273 : // Compare results.
274 0 : if (!sim.has_value()) {
275 0 : assert(!real || realcoin.IsSpent());
276 0 : } else {
277 0 : assert(real && !realcoin.IsSpent());
278 0 : const auto& simcoin = data.coins[sim->first];
279 0 : assert(realcoin.out == simcoin.out);
280 0 : assert(realcoin.fCoinBase == simcoin.fCoinBase);
281 0 : assert(realcoin.nHeight == sim->second);
282 : }
283 0 : },
284 :
285 0 : [&]() { // HaveCoin
286 0 : uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1);
287 : // Look up in simulation data.
288 0 : auto sim = lookup(outpointidx);
289 : // Look up in real caches.
290 0 : auto real = caches.back()->HaveCoin(data.outpoints[outpointidx]);
291 : // Compare results.
292 0 : assert(sim.has_value() == real);
293 0 : },
294 :
295 0 : [&]() { // HaveCoinInCache
296 0 : uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1);
297 : // Invoke on real cache (there is no equivalent in simulation, so nothing to compare result with).
298 0 : (void)caches.back()->HaveCoinInCache(data.outpoints[outpointidx]);
299 0 : },
300 :
301 0 : [&]() { // AccessCoin
302 0 : uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1);
303 : // Look up in simulation data.
304 0 : auto sim = lookup(outpointidx);
305 : // Look up in real caches.
306 0 : const auto& realcoin = caches.back()->AccessCoin(data.outpoints[outpointidx]);
307 : // Compare results.
308 0 : if (!sim.has_value()) {
309 0 : assert(realcoin.IsSpent());
310 0 : } else {
311 0 : assert(!realcoin.IsSpent());
312 0 : const auto& simcoin = data.coins[sim->first];
313 0 : assert(simcoin.out == realcoin.out);
314 0 : assert(simcoin.fCoinBase == realcoin.fCoinBase);
315 0 : assert(realcoin.nHeight == sim->second);
316 : }
317 0 : },
318 :
319 0 : [&]() { // AddCoin (only possible_overwrite if necessary)
320 0 : uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1);
321 0 : uint32_t coinidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_COINS - 1);
322 : // Look up in simulation data (to know whether we must set possible_overwrite or not).
323 0 : auto sim = lookup(outpointidx);
324 : // Invoke on real caches.
325 0 : Coin coin = data.coins[coinidx];
326 0 : coin.nHeight = current_height;
327 0 : caches.back()->AddCoin(data.outpoints[outpointidx], std::move(coin), sim.has_value());
328 : // Apply to simulation data.
329 0 : auto& entry = sim_caches[caches.size()].entry[outpointidx];
330 0 : entry.entrytype = EntryType::UNSPENT;
331 0 : entry.coinidx = coinidx;
332 0 : entry.height = current_height;
333 0 : },
334 :
335 0 : [&]() { // AddCoin (always possible_overwrite)
336 0 : uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1);
337 0 : uint32_t coinidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_COINS - 1);
338 : // Invoke on real caches.
339 0 : Coin coin = data.coins[coinidx];
340 0 : coin.nHeight = current_height;
341 0 : caches.back()->AddCoin(data.outpoints[outpointidx], std::move(coin), true);
342 : // Apply to simulation data.
343 0 : auto& entry = sim_caches[caches.size()].entry[outpointidx];
344 0 : entry.entrytype = EntryType::UNSPENT;
345 0 : entry.coinidx = coinidx;
346 0 : entry.height = current_height;
347 0 : },
348 :
349 0 : [&]() { // SpendCoin (moveto = nullptr)
350 0 : uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1);
351 : // Invoke on real caches.
352 0 : caches.back()->SpendCoin(data.outpoints[outpointidx], nullptr);
353 : // Apply to simulation data.
354 0 : sim_caches[caches.size()].entry[outpointidx].entrytype = EntryType::SPENT;
355 0 : },
356 :
357 0 : [&]() { // SpendCoin (with moveto)
358 0 : uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1);
359 : // Look up in simulation data (to compare the returned *moveto with).
360 0 : auto sim = lookup(outpointidx);
361 : // Invoke on real caches.
362 0 : Coin realcoin;
363 0 : caches.back()->SpendCoin(data.outpoints[outpointidx], &realcoin);
364 : // Apply to simulation data.
365 0 : sim_caches[caches.size()].entry[outpointidx].entrytype = EntryType::SPENT;
366 : // Compare *moveto with the value expected based on simulation data.
367 0 : if (!sim.has_value()) {
368 0 : assert(realcoin.IsSpent());
369 0 : } else {
370 0 : assert(!realcoin.IsSpent());
371 0 : const auto& simcoin = data.coins[sim->first];
372 0 : assert(simcoin.out == realcoin.out);
373 0 : assert(simcoin.fCoinBase == realcoin.fCoinBase);
374 0 : assert(realcoin.nHeight == sim->second);
375 : }
376 0 : },
377 :
378 0 : [&]() { // Uncache
379 0 : uint32_t outpointidx = provider.ConsumeIntegralInRange<uint32_t>(0, NUM_OUTPOINTS - 1);
380 : // Apply to real caches (there is no equivalent in our simulation).
381 0 : caches.back()->Uncache(data.outpoints[outpointidx]);
382 0 : },
383 :
384 0 : [&]() { // Add a cache level (if not already at the max).
385 0 : if (caches.size() != MAX_CACHES) {
386 : // Apply to real caches.
387 0 : caches.emplace_back(new CCoinsViewCache(&*caches.back(), /*deterministic=*/true));
388 : // Apply to simulation data.
389 0 : sim_caches[caches.size()].Wipe();
390 0 : }
391 0 : },
392 :
393 0 : [&]() { // Remove a cache level.
394 : // Apply to real caches (this reduces caches.size(), implicitly doing the same on the simulation data).
395 0 : caches.back()->SanityCheck();
396 0 : caches.pop_back();
397 0 : },
398 :
399 0 : [&]() { // Flush.
400 : // Apply to simulation data.
401 0 : flush();
402 : // Apply to real caches.
403 0 : caches.back()->Flush();
404 0 : },
405 :
406 0 : [&]() { // Sync.
407 : // Apply to simulation data (note that in our simulation, syncing and flushing is the same thing).
408 0 : flush();
409 : // Apply to real caches.
410 0 : caches.back()->Sync();
411 0 : },
412 :
413 0 : [&]() { // Flush + ReallocateCache.
414 : // Apply to simulation data.
415 0 : flush();
416 : // Apply to real caches.
417 0 : caches.back()->Flush();
418 0 : caches.back()->ReallocateCache();
419 0 : },
420 :
421 0 : [&]() { // GetCacheSize
422 0 : (void)caches.back()->GetCacheSize();
423 0 : },
424 :
425 0 : [&]() { // DynamicMemoryUsage
426 0 : (void)caches.back()->DynamicMemoryUsage();
427 0 : },
428 :
429 0 : [&]() { // Change height
430 0 : current_height = provider.ConsumeIntegralInRange<uint32_t>(1, current_height - 1);
431 0 : }
432 : );
433 0 : }
434 :
435 : // Sanity check all the remaining caches
436 0 : for (const auto& cache : caches) {
437 0 : cache->SanityCheck();
438 : }
439 :
440 : // Full comparison between caches and simulation data, from bottom to top,
441 : // as AccessCoin on a higher cache may affect caches below it.
442 0 : for (unsigned sim_idx = 1; sim_idx <= caches.size(); ++sim_idx) {
443 0 : auto& cache = *caches[sim_idx - 1];
444 0 : size_t cache_size = 0;
445 :
446 0 : for (uint32_t outpointidx = 0; outpointidx < NUM_OUTPOINTS; ++outpointidx) {
447 0 : cache_size += cache.HaveCoinInCache(data.outpoints[outpointidx]);
448 0 : const auto& real = cache.AccessCoin(data.outpoints[outpointidx]);
449 0 : auto sim = lookup(outpointidx, sim_idx);
450 0 : if (!sim.has_value()) {
451 0 : assert(real.IsSpent());
452 0 : } else {
453 0 : assert(!real.IsSpent());
454 0 : assert(real.out == data.coins[sim->first].out);
455 0 : assert(real.fCoinBase == data.coins[sim->first].fCoinBase);
456 0 : assert(real.nHeight == sim->second);
457 : }
458 0 : }
459 :
460 : // HaveCoinInCache ignores spent coins, so GetCacheSize() may exceed it. */
461 0 : assert(cache.GetCacheSize() >= cache_size);
462 0 : }
463 :
464 : // Compare the bottom coinsview (not a CCoinsViewCache) with sim_cache[0].
465 0 : for (uint32_t outpointidx = 0; outpointidx < NUM_OUTPOINTS; ++outpointidx) {
466 0 : Coin realcoin;
467 0 : bool real = bottom.GetCoin(data.outpoints[outpointidx], realcoin);
468 0 : auto sim = lookup(outpointidx, 0);
469 0 : if (!sim.has_value()) {
470 0 : assert(!real || realcoin.IsSpent());
471 0 : } else {
472 0 : assert(real && !realcoin.IsSpent());
473 0 : assert(realcoin.out == data.coins[sim->first].out);
474 0 : assert(realcoin.fCoinBase == data.coins[sim->first].fCoinBase);
475 0 : assert(realcoin.nHeight == sim->second);
476 : }
477 0 : }
478 0 : }
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