Branch data Line data Source code
1 : : // Copyright (c) 2020-2021 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 <chain.h>
6 : : #include <chainparams.h>
7 : : #include <common/args.h>
8 : : #include <consensus/params.h>
9 : : #include <primitives/block.h>
10 : : #include <util/chaintype.h>
11 : : #include <versionbits.h>
12 : :
13 : : #include <test/fuzz/FuzzedDataProvider.h>
14 : : #include <test/fuzz/fuzz.h>
15 : : #include <test/fuzz/util.h>
16 : :
17 : : #include <cstdint>
18 : : #include <limits>
19 : : #include <memory>
20 : : #include <vector>
21 : :
22 : : namespace {
23 : : class TestConditionChecker : public AbstractThresholdConditionChecker
24 : : {
25 : : private:
26 : : mutable ThresholdConditionCache m_cache;
27 : : const Consensus::Params dummy_params{};
28 : :
29 : : public:
30 : : const int64_t m_begin;
31 : : const int64_t m_end;
32 : : const int m_period;
33 : : const int m_threshold;
34 : : const int m_min_activation_height;
35 : : const int m_bit;
36 : :
37 : 220 : TestConditionChecker(int64_t begin, int64_t end, int period, int threshold, int min_activation_height, int bit)
38 [ + + - + ]: 440 : : m_begin{begin}, m_end{end}, m_period{period}, m_threshold{threshold}, m_min_activation_height{min_activation_height}, m_bit{bit}
39 : : {
40 [ - + ]: 220 : assert(m_period > 0);
41 [ + - - + ]: 220 : assert(0 <= m_threshold && m_threshold <= m_period);
42 [ - + ]: 220 : assert(0 <= m_bit && m_bit < 32 && m_bit < VERSIONBITS_NUM_BITS);
43 [ - + ]: 220 : assert(0 <= m_min_activation_height);
44 : 220 : }
45 : :
46 : 405056 : bool Condition(const CBlockIndex* pindex, const Consensus::Params& params) const override { return Condition(pindex->nVersion); }
47 : 67699 : int64_t BeginTime(const Consensus::Params& params) const override { return m_begin; }
48 : 61561 : int64_t EndTime(const Consensus::Params& params) const override { return m_end; }
49 : 78037 : int Period(const Consensus::Params& params) const override { return m_period; }
50 : 73279 : int Threshold(const Consensus::Params& params) const override { return m_threshold; }
51 : 61561 : int MinActivationHeight(const Consensus::Params& params) const override { return m_min_activation_height; }
52 : :
53 : 6138 : ThresholdState GetStateFor(const CBlockIndex* pindexPrev) const { return AbstractThresholdConditionChecker::GetStateFor(pindexPrev, dummy_params, m_cache); }
54 : 6138 : int GetStateSinceHeightFor(const CBlockIndex* pindexPrev) const { return AbstractThresholdConditionChecker::GetStateSinceHeightFor(pindexPrev, dummy_params, m_cache); }
55 : 11718 : BIP9Stats GetStateStatisticsFor(const CBlockIndex* pindex, std::vector<bool>* signals=nullptr) const { return AbstractThresholdConditionChecker::GetStateStatisticsFor(pindex, dummy_params, signals); }
56 : :
57 : 208894 : bool Condition(int32_t version) const
58 : : {
59 : 208894 : uint32_t mask = (uint32_t{1}) << m_bit;
60 [ + + + + : 205894 : return (((version & VERSIONBITS_TOP_MASK) == VERSIONBITS_TOP_BITS) && (version & mask) != 0);
+ + + + +
+ + + ]
61 : : }
62 : :
63 : 11904 : bool Condition(const CBlockIndex* pindex) const { return Condition(pindex->nVersion); }
64 : : };
65 : :
66 : : /** Track blocks mined for test */
67 : 0 : class Blocks
68 : : {
69 : : private:
70 : : std::vector<std::unique_ptr<CBlockIndex>> m_blocks;
71 : : const uint32_t m_start_time;
72 : : const uint32_t m_interval;
73 : : const int32_t m_signal;
74 : : const int32_t m_no_signal;
75 : :
76 : : public:
77 : 186 : Blocks(uint32_t start_time, uint32_t interval, int32_t signal, int32_t no_signal)
78 : 186 : : m_start_time{start_time}, m_interval{interval}, m_signal{signal}, m_no_signal{no_signal} {}
79 : :
80 : 2615 : size_t size() const { return m_blocks.size(); }
81 : :
82 : 83866 : CBlockIndex* tip() const
83 : : {
84 [ + + ]: 83866 : return m_blocks.empty() ? nullptr : m_blocks.back().get();
85 : : }
86 : :
87 : 83680 : CBlockIndex* mine_block(bool signal)
88 : : {
89 : 83680 : CBlockHeader header;
90 [ + + ]: 83680 : header.nVersion = signal ? m_signal : m_no_signal;
91 : 83680 : header.nTime = m_start_time + m_blocks.size() * m_interval;
92 : 83680 : header.nBits = 0x1d00ffff;
93 : :
94 : 83680 : auto current_block = std::make_unique<CBlockIndex>(header);
95 [ + - ]: 83680 : current_block->pprev = tip();
96 [ + - ]: 83680 : current_block->nHeight = m_blocks.size();
97 [ + - ]: 83680 : current_block->BuildSkip();
98 : :
99 [ + - ]: 83680 : return m_blocks.emplace_back(std::move(current_block)).get();
100 : 83680 : }
101 : : };
102 : :
103 : : std::unique_ptr<const CChainParams> g_params;
104 : :
105 : 1 : void initialize()
106 : : {
107 : : // this is actually comparatively slow, so only do it once
108 [ + - ]: 2 : g_params = CreateChainParams(ArgsManager{}, ChainType::MAIN);
109 [ - + ]: 1 : assert(g_params != nullptr);
110 : 1 : }
111 : :
112 : : constexpr uint32_t MAX_START_TIME = 4102444800; // 2100-01-01
113 : :
114 [ + - ]: 632 : FUZZ_TARGET(versionbits, .init = initialize)
115 : : {
116 [ - + ]: 220 : const CChainParams& params = *g_params;
117 : 220 : const int64_t interval = params.GetConsensus().nPowTargetSpacing;
118 [ - + ]: 220 : assert(interval > 1); // need to be able to halve it
119 [ - + ]: 220 : assert(interval < std::numeric_limits<int32_t>::max());
120 : :
121 : 220 : FuzzedDataProvider fuzzed_data_provider(buffer.data(), buffer.size());
122 : :
123 : : // making period/max_periods larger slows these tests down significantly
124 : 220 : const int period = 32;
125 : 220 : const size_t max_periods = 16;
126 : 220 : const size_t max_blocks = 2 * period * max_periods;
127 : :
128 : 220 : const int threshold = fuzzed_data_provider.ConsumeIntegralInRange(1, period);
129 [ - + ]: 220 : assert(0 < threshold && threshold <= period); // must be able to both pass and fail threshold!
130 : :
131 : : // too many blocks at 10min each might cause uint32_t time to overflow if
132 : : // block_start_time is at the end of the range above
133 [ - + ]: 220 : assert(std::numeric_limits<uint32_t>::max() - MAX_START_TIME > interval * max_blocks);
134 : :
135 : 220 : const int64_t block_start_time = fuzzed_data_provider.ConsumeIntegralInRange<uint32_t>(params.GenesisBlock().nTime, MAX_START_TIME);
136 : :
137 : : // what values for version will we use to signal / not signal?
138 : 220 : const int32_t ver_signal = fuzzed_data_provider.ConsumeIntegral<int32_t>();
139 : 220 : const int32_t ver_nosignal = fuzzed_data_provider.ConsumeIntegral<int32_t>();
140 : :
141 : : // select deployment parameters: bit, start time, timeout
142 : 220 : const int bit = fuzzed_data_provider.ConsumeIntegralInRange<int>(0, VERSIONBITS_NUM_BITS - 1);
143 : :
144 : 220 : bool always_active_test = false;
145 : 220 : bool never_active_test = false;
146 : 220 : int64_t start_time;
147 : 220 : int64_t timeout;
148 [ + + ]: 220 : if (fuzzed_data_provider.ConsumeBool()) {
149 : : // pick the timestamp to switch based on a block
150 : : // note states will change *after* these blocks because mediantime lags
151 : 168 : int start_block = fuzzed_data_provider.ConsumeIntegralInRange<int>(0, period * (max_periods - 3));
152 : 168 : int end_block = fuzzed_data_provider.ConsumeIntegralInRange<int>(0, period * (max_periods - 3));
153 : :
154 : 168 : start_time = block_start_time + start_block * interval;
155 : 168 : timeout = block_start_time + end_block * interval;
156 : :
157 : : // allow for times to not exactly match a block
158 [ + + ]: 168 : if (fuzzed_data_provider.ConsumeBool()) start_time += interval / 2;
159 [ + + ]: 168 : if (fuzzed_data_provider.ConsumeBool()) timeout += interval / 2;
160 : : } else {
161 [ + + ]: 52 : if (fuzzed_data_provider.ConsumeBool()) {
162 : : start_time = Consensus::BIP9Deployment::ALWAYS_ACTIVE;
163 : : always_active_test = true;
164 : : } else {
165 : 43 : start_time = Consensus::BIP9Deployment::NEVER_ACTIVE;
166 : 43 : never_active_test = true;
167 : : }
168 [ + + ]: 52 : timeout = fuzzed_data_provider.ConsumeBool() ? Consensus::BIP9Deployment::NO_TIMEOUT : fuzzed_data_provider.ConsumeIntegral<int64_t>();
169 : : }
170 : 220 : int min_activation = fuzzed_data_provider.ConsumeIntegralInRange<int>(0, period * max_periods);
171 : :
172 : 220 : TestConditionChecker checker(start_time, timeout, period, threshold, min_activation, bit);
173 : :
174 : : // Early exit if the versions don't signal sensibly for the deployment
175 [ + + ]: 220 : if (!checker.Condition(ver_signal)) return;
176 [ + + ]: 194 : if (checker.Condition(ver_nosignal)) return;
177 [ + + ]: 192 : if (ver_nosignal < 0) return;
178 : :
179 : : // TOP_BITS should ensure version will be positive and meet min
180 : : // version requirement
181 [ - + ]: 186 : assert(ver_signal > 0);
182 [ - + ]: 186 : assert(ver_signal >= VERSIONBITS_LAST_OLD_BLOCK_VERSION);
183 : :
184 : : // Now that we have chosen time and versions, setup to mine blocks
185 : 186 : Blocks blocks(block_start_time, interval, ver_signal, ver_nosignal);
186 : :
187 : : /* Strategy:
188 : : * * we will mine a final period worth of blocks, with
189 : : * randomised signalling according to a mask
190 : : * * but before we mine those blocks, we will mine some
191 : : * randomised number of prior periods; with either all
192 : : * or no blocks in the period signalling
193 : : *
194 : : * We establish the mask first, then consume "bools" until
195 : : * we run out of fuzz data to work out how many prior periods
196 : : * there are and which ones will signal.
197 : : */
198 : :
199 : : // establish the mask
200 : 186 : const uint32_t signalling_mask = fuzzed_data_provider.ConsumeIntegral<uint32_t>();
201 : :
202 : : // mine prior periods
203 [ + + ]: 2775 : while (fuzzed_data_provider.remaining_bytes() > 0) { // early exit; no need for LIMITED_WHILE
204 : : // all blocks in these periods either do or don't signal
205 : 2429 : bool signal = fuzzed_data_provider.ConsumeBool();
206 [ + + ]: 80157 : for (int b = 0; b < period; ++b) {
207 [ + - ]: 77728 : blocks.mine_block(signal);
208 : : }
209 : :
210 : : // don't risk exceeding max_blocks or times may wrap around
211 [ + + ]: 2429 : if (blocks.size() + 2 * period > max_blocks) break;
212 : : }
213 : : // NOTE: fuzzed_data_provider may be fully consumed at this point and should not be used further
214 : :
215 : : // now we mine the final period and check that everything looks sane
216 : :
217 : : // count the number of signalling blocks
218 : 186 : int blocks_sig = 0;
219 : :
220 : : // get the info for the first block of the period
221 : 186 : CBlockIndex* prev = blocks.tip();
222 [ + - ]: 186 : const int exp_since = checker.GetStateSinceHeightFor(prev);
223 [ + - ]: 186 : const ThresholdState exp_state = checker.GetStateFor(prev);
224 : :
225 : : // get statistics from end of previous period, then reset
226 : 186 : BIP9Stats last_stats;
227 : 186 : last_stats.period = period;
228 : 186 : last_stats.threshold = threshold;
229 : 186 : last_stats.count = last_stats.elapsed = 0;
230 : 186 : last_stats.possible = (period >= threshold);
231 : 186 : std::vector<bool> last_signals{};
232 : :
233 [ + + ]: 186 : int prev_next_height = (prev == nullptr ? 0 : prev->nHeight + 1);
234 [ - + ]: 186 : assert(exp_since <= prev_next_height);
235 : :
236 : : // mine (period-1) blocks and check state
237 [ + + ]: 5952 : for (int b = 1; b < period; ++b) {
238 : 5766 : const bool signal = (signalling_mask >> (b % 32)) & 1;
239 [ + + ]: 5766 : if (signal) ++blocks_sig;
240 : :
241 [ + - ]: 5766 : CBlockIndex* current_block = blocks.mine_block(signal);
242 : :
243 : : // verify that signalling attempt was interpreted correctly
244 [ + + - + ]: 11532 : assert(checker.Condition(current_block) == signal);
245 : :
246 : : // state and since don't change within the period
247 [ + - ]: 5766 : const ThresholdState state = checker.GetStateFor(current_block);
248 [ + - ]: 5766 : const int since = checker.GetStateSinceHeightFor(current_block);
249 [ - + ]: 5766 : assert(state == exp_state);
250 [ - + ]: 5766 : assert(since == exp_since);
251 : :
252 : : // check that after mining this block stats change as expected
253 : 5766 : std::vector<bool> signals;
254 [ + - ]: 5766 : const BIP9Stats stats = checker.GetStateStatisticsFor(current_block, &signals);
255 [ + - ]: 5766 : const BIP9Stats stats_no_signals = checker.GetStateStatisticsFor(current_block);
256 [ + - + - : 5766 : assert(stats.period == stats_no_signals.period && stats.threshold == stats_no_signals.threshold
+ - + - -
+ ]
257 : : && stats.elapsed == stats_no_signals.elapsed && stats.count == stats_no_signals.count
258 : : && stats.possible == stats_no_signals.possible);
259 : :
260 [ - + ]: 5766 : assert(stats.period == period);
261 [ - + ]: 5766 : assert(stats.threshold == threshold);
262 [ - + ]: 5766 : assert(stats.elapsed == b);
263 [ + + - + ]: 8992 : assert(stats.count == last_stats.count + (signal ? 1 : 0));
264 [ - + ]: 5766 : assert(stats.possible == (stats.count + period >= stats.elapsed + threshold));
265 : 5766 : last_stats = stats;
266 : :
267 [ - + ]: 5766 : assert(signals.size() == last_signals.size() + 1);
268 [ - + ]: 5766 : assert(signals.back() == signal);
269 [ + - ]: 5766 : last_signals.push_back(signal);
270 [ - + ]: 5766 : assert(signals == last_signals);
271 : 5766 : }
272 : :
273 [ + + ]: 186 : if (exp_state == ThresholdState::STARTED) {
274 : : // double check that stats.possible is sane
275 [ + + - + ]: 32 : if (blocks_sig >= threshold - 1) assert(last_stats.possible);
276 : : }
277 : :
278 : : // mine the final block
279 : 186 : bool signal = (signalling_mask >> (period % 32)) & 1;
280 [ + + ]: 186 : if (signal) ++blocks_sig;
281 [ + - ]: 186 : CBlockIndex* current_block = blocks.mine_block(signal);
282 [ + + - + ]: 372 : assert(checker.Condition(current_block) == signal);
283 : :
284 [ + - ]: 186 : const BIP9Stats stats = checker.GetStateStatisticsFor(current_block);
285 [ - + ]: 186 : assert(stats.period == period);
286 [ - + ]: 186 : assert(stats.threshold == threshold);
287 [ - + ]: 186 : assert(stats.elapsed == period);
288 [ - + ]: 186 : assert(stats.count == blocks_sig);
289 [ - + ]: 186 : assert(stats.possible == (stats.count + period >= stats.elapsed + threshold));
290 : :
291 : : // More interesting is whether the state changed.
292 [ + - ]: 186 : const ThresholdState state = checker.GetStateFor(current_block);
293 [ + - ]: 186 : const int since = checker.GetStateSinceHeightFor(current_block);
294 : :
295 : : // since is straightforward:
296 [ - + ]: 186 : assert(since % period == 0);
297 [ + - - + ]: 186 : assert(0 <= since && since <= current_block->nHeight + 1);
298 [ + + ]: 186 : if (state == exp_state) {
299 [ - + ]: 149 : assert(since == exp_since);
300 : : } else {
301 [ - + ]: 37 : assert(since == current_block->nHeight + 1);
302 : : }
303 : :
304 : : // state is where everything interesting is
305 [ + + + + : 186 : switch (state) {
+ - ]
306 : 16 : case ThresholdState::DEFINED:
307 [ - + ]: 16 : assert(since == 0);
308 [ - + ]: 16 : assert(exp_state == ThresholdState::DEFINED);
309 [ - + ]: 16 : assert(current_block->GetMedianTimePast() < checker.m_begin);
310 : : break;
311 : 17 : case ThresholdState::STARTED:
312 [ - + ]: 17 : assert(current_block->GetMedianTimePast() >= checker.m_begin);
313 [ + + ]: 17 : if (exp_state == ThresholdState::STARTED) {
314 [ - + ]: 11 : assert(blocks_sig < threshold);
315 [ - + ]: 11 : assert(current_block->GetMedianTimePast() < checker.m_end);
316 : : } else {
317 [ - + ]: 6 : assert(exp_state == ThresholdState::DEFINED);
318 : : }
319 : : break;
320 : 15 : case ThresholdState::LOCKED_IN:
321 [ + + ]: 15 : if (exp_state == ThresholdState::LOCKED_IN) {
322 [ - + ]: 7 : assert(current_block->nHeight + 1 < min_activation);
323 : : } else {
324 [ - + ]: 8 : assert(exp_state == ThresholdState::STARTED);
325 [ - + ]: 8 : assert(blocks_sig >= threshold);
326 : : }
327 : : break;
328 : 80 : case ThresholdState::ACTIVE:
329 [ + + - + ]: 80 : assert(always_active_test || min_activation <= current_block->nHeight + 1);
330 [ - + ]: 80 : assert(exp_state == ThresholdState::ACTIVE || exp_state == ThresholdState::LOCKED_IN);
331 : : break;
332 : 58 : case ThresholdState::FAILED:
333 [ + + - + ]: 58 : assert(never_active_test || current_block->GetMedianTimePast() >= checker.m_end);
334 [ + + ]: 58 : if (exp_state == ThresholdState::STARTED) {
335 [ - + ]: 13 : assert(blocks_sig < threshold);
336 : : } else {
337 [ - + ]: 45 : assert(exp_state == ThresholdState::FAILED);
338 : : }
339 : : break;
340 : 0 : default:
341 : 0 : assert(false);
342 : : }
343 : :
344 [ + + ]: 186 : if (blocks.size() >= period * max_periods) {
345 : : // we chose the timeout (and block times) so that by the time we have this many blocks it's all over
346 [ - + ]: 79 : assert(state == ThresholdState::ACTIVE || state == ThresholdState::FAILED);
347 : : }
348 : :
349 [ + + ]: 186 : if (always_active_test) {
350 : : // "always active" has additional restrictions
351 [ - + ]: 6 : assert(state == ThresholdState::ACTIVE);
352 [ - + ]: 6 : assert(exp_state == ThresholdState::ACTIVE);
353 [ - + ]: 6 : assert(since == 0);
354 [ + + ]: 180 : } else if (never_active_test) {
355 : : // "never active" does too
356 [ - + ]: 14 : assert(state == ThresholdState::FAILED);
357 [ - + ]: 14 : assert(exp_state == ThresholdState::FAILED);
358 [ - + ]: 14 : assert(since == 0);
359 : : } else {
360 : : // for signalled deployments, the initial state is always DEFINED
361 [ - + ]: 166 : assert(since > 0 || state == ThresholdState::DEFINED);
362 [ - + ]: 166 : assert(exp_since > 0 || exp_state == ThresholdState::DEFINED);
363 : : }
364 : 220 : }
365 : : } // namespace
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