READ THE CODE

Inside Bitcoin

The code behind the network, with room to understand it.

Stable release v32.1bitcoin/bitcoin · f0de87f04062 ↗3,020 source files · 47.5 MB stored on the server440 file guides

Release published 2026-10-28 · Snapshot fetched 2026-11-01. Latest stable release at fetch time; development branches and Git history are excluded. Only the selected code window and visible folders load here.

14,234 bytes · SHA-256 dd15d4afd8de9684… · View upstream ↗

1// Copyright (c) 2020-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 <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#include <versionbits_impl.h>
13
14#include <test/fuzz/FuzzedDataProvider.h>
15#include <test/fuzz/fuzz.h>
16#include <test/fuzz/util.h>
17#include <test/util/versionbits.h>
18
19#include <cstdint>
20#include <limits>
21#include <memory>
22#include <vector>
23
24namespace {
25class TestConditionChecker : public VersionBitsConditionChecker
26{
27private:
28    mutable ThresholdConditionCache m_cache;
29
30public:
31    TestConditionChecker(const Consensus::BIP9Deployment& dep) : VersionBitsConditionChecker{dep}
32    {
33        assert(dep.period > 0);
34        assert(dep.threshold <= dep.period);
35        assert(0 <= dep.bit && dep.bit < 32 && dep.bit < VERSIONBITS_MAX_NUM_BITS);
36        assert(0 <= dep.min_activation_height);
37    }
38
39    ThresholdState GetStateFor(const CBlockIndex* pindexPrev) const { return AbstractThresholdConditionChecker::GetStateFor(pindexPrev, m_cache); }
40    int GetStateSinceHeightFor(const CBlockIndex* pindexPrev) const { return AbstractThresholdConditionChecker::GetStateSinceHeightFor(pindexPrev, m_cache); }
41};
42
43/** Track blocks mined for test */
44class Blocks
45{
46private:
47    std::vector<std::unique_ptr<CBlockIndex>> m_blocks;
48    const uint32_t m_start_time;
49    const uint32_t m_interval;
50    const int32_t m_signal;
51    const int32_t m_no_signal;
52
53public:
54    Blocks(uint32_t start_time, uint32_t interval, int32_t signal, int32_t no_signal)
55        : m_start_time{start_time}, m_interval{interval}, m_signal{signal}, m_no_signal{no_signal} {}
56
57    size_t size() const { return m_blocks.size(); }
58
59    CBlockIndex* tip() const
60    {
61        return m_blocks.empty() ? nullptr : m_blocks.back().get();
62    }
63
64    CBlockIndex* mine_block(bool signal)
65    {
66        CBlockHeader header;
67        header.nVersion = signal ? m_signal : m_no_signal;
68        header.nTime = m_start_time + m_blocks.size() * m_interval;
69        header.nBits = 0x1d00ffff;
70
71        auto current_block = std::make_unique<CBlockIndex>(header);
72        current_block->pprev = tip();
73        current_block->nHeight = m_blocks.size();
74        current_block->BuildSkip();
75
76        return m_blocks.emplace_back(std::move(current_block)).get();
77    }
78};
79
80std::unique_ptr<const CChainParams> g_params;
81
82void initialize()
83{
84    // this is actually comparatively slow, so only do it once
85    g_params = CreateChainParams(ArgsManager{}, ChainType::MAIN);
86    assert(g_params != nullptr);
87}
88
89constexpr uint32_t MAX_START_TIME = 4102444800; // 2100-01-01
90
91FUZZ_TARGET(versionbits, .init = initialize)
92{
93    const CChainParams& params = *g_params;
94    const int64_t interval = params.GetConsensus().nPowTargetSpacing;
95    assert(interval > 1); // need to be able to halve it
96    assert(interval < std::numeric_limits<int32_t>::max());
97
98    FuzzedDataProvider fuzzed_data_provider(buffer.data(), buffer.size());
99
100    // making period/max_periods larger slows these tests down significantly
101    const uint32_t period = 32;
102    const size_t max_periods = 16;
103    const size_t max_blocks = 2 * period * max_periods;
104
105    // too many blocks at 10min each might cause uint32_t time to overflow if
106    // block_start_time is at the end of the range above
107    assert(std::numeric_limits<uint32_t>::max() - MAX_START_TIME > interval * max_blocks);
108
109    const int64_t block_start_time = fuzzed_data_provider.ConsumeIntegralInRange<uint32_t>(params.GenesisBlock().nTime, MAX_START_TIME);
110
111    // what values for version will we use to signal / not signal?
112    const int32_t ver_signal = fuzzed_data_provider.ConsumeIntegral<int32_t>();
113    const int32_t ver_nosignal = fuzzed_data_provider.ConsumeIntegral<int32_t>();
114    if (ver_nosignal < 0) return; // negative values are uninteresting
115
116    // Now that we have chosen time and versions, setup to mine blocks
117    Blocks blocks(block_start_time, interval, ver_signal, ver_nosignal);
118
119    const bool always_active_test = fuzzed_data_provider.ConsumeBool();
120    const bool never_active_test = !always_active_test && fuzzed_data_provider.ConsumeBool();
121
122    const Consensus::BIP9Deployment dep{[&]() {
123        Consensus::BIP9Deployment dep;
124        dep.period = period;
125
126        dep.threshold = fuzzed_data_provider.ConsumeIntegralInRange<uint32_t>(1, period);
127        assert(0 < dep.threshold && dep.threshold <= dep.period); // must be able to both pass and fail threshold!
128
129        // select deployment parameters: bit, start time, timeout
130        dep.bit = fuzzed_data_provider.ConsumeIntegralInRange<int>(0, VERSIONBITS_MAX_NUM_BITS - 1);
131
132        if (always_active_test) {
133            dep.nStartTime = Consensus::BIP9Deployment::ALWAYS_ACTIVE;
134            dep.nTimeout = fuzzed_data_provider.ConsumeBool() ? Consensus::BIP9Deployment::NO_TIMEOUT : fuzzed_data_provider.ConsumeIntegral<int64_t>();
135        } else if (never_active_test) {
136            dep.nStartTime = Consensus::BIP9Deployment::NEVER_ACTIVE;
137            dep.nTimeout = fuzzed_data_provider.ConsumeBool() ? Consensus::BIP9Deployment::NO_TIMEOUT : fuzzed_data_provider.ConsumeIntegral<int64_t>();
138        } else {
139            // pick the timestamp to switch based on a block
140            // note states will change *after* these blocks because mediantime lags
141            int start_block = fuzzed_data_provider.ConsumeIntegralInRange<int>(0, period * (max_periods - 3));
142            int end_block = fuzzed_data_provider.ConsumeIntegralInRange<int>(0, period * (max_periods - 3));
143
144            dep.nStartTime = block_start_time + start_block * interval;
145            dep.nTimeout = block_start_time + end_block * interval;
146
147            // allow for times to not exactly match a block
148            if (fuzzed_data_provider.ConsumeBool()) dep.nStartTime += interval / 2;
149            if (fuzzed_data_provider.ConsumeBool()) dep.nTimeout += interval / 2;
150        }
151        dep.min_activation_height = fuzzed_data_provider.ConsumeIntegralInRange<int>(0, period * max_periods);
152        return dep;
153    }()};
154    TestConditionChecker checker(dep);
155
156    // Early exit if the versions don't signal sensibly for the deployment
157    if (!checker.Condition(ver_signal)) return;
158    if (checker.Condition(ver_nosignal)) return;
159
160    // TOP_BITS should ensure version will be positive and meet min
161    // version requirement
162    assert(ver_signal > 0);
163    assert(ver_signal >= VERSIONBITS_LAST_OLD_BLOCK_VERSION);
164
165    /* Strategy:
166     *  * we will mine a final period worth of blocks, with
167     *    randomised signalling according to a mask
168     *  * but before we mine those blocks, we will mine some
169     *    randomised number of prior periods; with either all
170     *    or no blocks in the period signalling
171     *
172     * We establish the mask first, then consume "bools" until
173     * we run out of fuzz data to work out how many prior periods
174     * there are and which ones will signal.
175     */
176
177    // establish the mask
178    const uint32_t signalling_mask = fuzzed_data_provider.ConsumeIntegral<uint32_t>();
179
180    // mine prior periods
181    while (fuzzed_data_provider.remaining_bytes() > 0) { // early exit; no need for LIMITED_WHILE
182        // all blocks in these periods either do or don't signal
183        bool signal = fuzzed_data_provider.ConsumeBool();
184        for (uint32_t b = 0; b < period; ++b) {
185            blocks.mine_block(signal);
186        }
187
188        // don't risk exceeding max_blocks or times may wrap around
189        if (blocks.size() + 2 * period > max_blocks) break;
190    }
191    // NOTE: fuzzed_data_provider may be fully consumed at this point and should not be used further
192
193    // now we mine the final period and check that everything looks sane
194
195    // count the number of signalling blocks
196    uint32_t blocks_sig = 0;
197
198    // get the info for the first block of the period
199    CBlockIndex* prev = blocks.tip();
200    const int exp_since = checker.GetStateSinceHeightFor(prev);
201    const ThresholdState exp_state = checker.GetStateFor(prev);
202
203    // get statistics from end of previous period, then reset
204    BIP9Stats last_stats;
205    last_stats.period = period;
206    last_stats.threshold = dep.threshold;
207    last_stats.count = last_stats.elapsed = 0;
208    last_stats.possible = (period >= dep.threshold);
209    std::vector<bool> last_signals{};
210
211    int prev_next_height = (prev == nullptr ? 0 : prev->nHeight + 1);
212    assert(exp_since <= prev_next_height);
213
214    // mine (period-1) blocks and check state
215    for (uint32_t b = 1; b < period; ++b) {
216        const bool signal = (signalling_mask >> (b % 32)) & 1;
217        if (signal) ++blocks_sig;
218
219        CBlockIndex* current_block = blocks.mine_block(signal);
220
221        // verify that signalling attempt was interpreted correctly
222        assert(checker.Condition(current_block->nVersion) == signal);
223
224        // state and since don't change within the period
225        const ThresholdState state = checker.GetStateFor(current_block);
226        const int since = checker.GetStateSinceHeightFor(current_block);
227        assert(state == exp_state);
228        assert(since == exp_since);
229
230        // check that after mining this block stats change as expected
231        std::vector<bool> signals;
232        const BIP9Stats stats = checker.GetStateStatisticsFor(current_block, &signals);
233        const BIP9Stats stats_no_signals = checker.GetStateStatisticsFor(current_block);
234        assert(stats.period == stats_no_signals.period && stats.threshold == stats_no_signals.threshold
235               && stats.elapsed == stats_no_signals.elapsed && stats.count == stats_no_signals.count
236               && stats.possible == stats_no_signals.possible);
237
238        assert(stats.period == period);
239        assert(stats.threshold == dep.threshold);
240        assert(stats.elapsed == b);
241        assert(stats.count == last_stats.count + (signal ? 1 : 0));
242        assert(stats.possible == (stats.count + period >= stats.elapsed + dep.threshold));
243        last_stats = stats;
244
245        assert(signals.size() == last_signals.size() + 1);
246        assert(signals.back() == signal);
247        last_signals.push_back(signal);
248        assert(signals == last_signals);
249    }
250

src/wallet/receive.cpp

src/wallet/coinselection.cpp

src/consensus/validation.h

src/primitives/transaction.cpp

src/script/descriptor.cpp

src/bitcoin-cli.cpp

src/rpc/blockchain.cpp

src/rpc/rawtransaction.cpp

src/init.cpp

src/crypto/sha256.cpp

src/consensus/merkle.h

src/consensus/tx_check.h

src/consensus/tx_verify.h

src/policy/feerate.h

src/policy/feerate.cpp

src/primitives/transaction_identifier.h

src/chainparamsbase.h

src/chainparamsbase.cpp

src/util/moneystr.cpp

src/crypto/ripemd160.h

src/crypto/sha1.h

src/crypto/sha512.h

src/crypto/hmac_sha256.h

src/crypto/hmac_sha512.h

src/crypto/hmac_sha256.cpp

src/crypto/hmac_sha512.cpp

src/crypto/hkdf_sha256_32.h

src/crypto/hkdf_sha256_32.cpp

src/support/cleanse.h

src/support/cleanse.cpp

src/crypto/siphash.cpp

src/crypto/muhash.h

src/crypto/chacha20.h

src/crypto/poly1305.h

src/crypto/chacha20poly1305.h

src/crypto/chacha20poly1305.cpp

src/util/chaintype.cpp

src/util/obfuscation.h

src/util/byte_units.h

src/util/overflow.h

src/blockencodings.cpp

src/net_permissions.cpp

src/policy/packages.cpp

src/policy/rbf.cpp

src/policy/truc_policy.cpp

src/policy/ephemeral_policy.cpp

src/policy/settings.cpp

src/policy/policy.cpp

src/node/transaction.cpp

src/node/coin.cpp

src/rpc/client.cpp

src/rpc/external_signer.cpp

src/rpc/request.cpp

src/rpc/server_util.cpp

src/rpc/fees.cpp

src/rpc/output_script.cpp

src/rpc/rawtransaction_util.cpp

src/rpc/rawtransaction_util.h

src/rpc/register.h

src/rpc/request.h

src/rpc/server_util.h

src/rpc/protocol.h

src/rpc/server.h

src/rpc/signmessage.cpp

src/rpc/txoutproof.cpp

src/rpc/util.cpp

src/rpc/util.h

src/wallet/rpc/addresses.cpp

src/wallet/rpc/backup.cpp

src/wallet/rpc/coins.cpp

src/wallet/rpc/encrypt.cpp

src/wallet/rpc/signmessage.cpp

src/wallet/rpc/util.cpp

src/wallet/rpc/util.h

src/wallet/coincontrol.cpp

src/wallet/coincontrol.h

src/wallet/context.cpp

src/wallet/context.h

src/wallet/crypter.cpp

src/wallet/crypter.h

src/wallet/db.cpp

src/wallet/export.cpp

src/wallet/external_signer_scriptpubkeyman.cpp

src/wallet/rpc/spend.cpp

src/wallet/rpc/transactions.cpp

src/wallet/rpc/wallet.cpp

src/wallet/feebumper.cpp

src/wallet/feebumper.h

src/index/base.h

src/index/base.cpp

src/index/txindex.h

src/index/txindex.cpp

src/index/txindex_key.h

src/index/txospenderindex.h

src/index/txospenderindex.cpp

src/index/blockfilterindex.h

src/index/blockfilterindex.cpp

src/index/coinstatsindex.h

src/index/coinstatsindex.cpp

src/index/db_key.h

src/index/disktxpos.h

src/kernel/chain.cpp

src/kernel/chain.h

src/kernel/checks.cpp

src/kernel/checks.h

src/kernel/context.cpp

src/kernel/context.h

src/kernel/cs_main.cpp

src/kernel/cs_main.h

src/kernel/disconnected_transactions.cpp

src/kernel/disconnected_transactions.h

src/kernel/mempool_removal_reason.cpp

src/kernel/mempool_removal_reason.h

src/kernel/coinstats.cpp

src/kernel/coinstats.h

src/kernel/chainparams.cpp

src/kernel/chainparams.h

src/wallet/sqlite.cpp

src/wallet/sqlite.h

src/wallet/transaction.cpp

src/wallet/transaction.h

src/wallet/dump.cpp

src/wallet/dump.h

src/wallet/init.cpp

src/wallet/walletutil.cpp

src/wallet/walletutil.h

src/wallet/wallettool.cpp

src/wallet/wallettool.h

src/wallet/export.h

src/wallet/migrate.cpp

src/wallet/migrate.h

src/wallet/db.h

src/wallet/walletdb.cpp

src/wallet/interfaces.cpp

src/wallet/scriptpubkeyman.cpp

src/wallet/scriptpubkeyman.h

src/kernel/bitcoinkernel.cpp

src/kernel/bitcoinkernel.h

src/kernel/bitcoinkernel_wrapper.h

src/node/chainstate.cpp

src/node/chainstate.h

src/node/blockstorage.cpp

src/node/blockstorage.h

src/node/mempool_persist.cpp

src/node/mempool_persist.h

src/node/utxo_snapshot.cpp

src/node/utxo_snapshot.h

src/node/kernel_notifications.cpp

src/node/kernel_notifications.h

src/node/blockmanager_args.cpp

src/kernel/blockmanager_opts.h

src/util/expected.cpp

src/policy/settings.h

src/util/types.h

src/kernel/messagestartchars.h

src/kernel/warning.h

src/util/exception.h

src/common/license_info.h

src/node/coins_view_args.h

src/node/database_args.h

src/util/batchpriority.h

src/util/ui_change_type.h

src/node/coins_view_args.cpp

src/node/peerman_args.h

src/util/serfloat.h

src/node/blockmanager_args.h

src/node/database_args.cpp

src/util/overloaded.h

src/interfaces/types.h

src/node/chainstatemanager_args.h

src/node/minisketchwrapper.h

src/util/macros.h

src/util/syserror.h

src/common/run_command.h

src/util/bytevectorhash.cpp

src/node/mempool_persist_args.cpp

src/util/exec.h

src/util/rbf.h

src/crypto/hex_base.h

src/node/mempool_persist_args.h

src/interfaces/echo.h

src/util/any.h

src/util/batchpriority.cpp

src/util/threadnames.h

src/node/coin.h

src/node/mempool_args.h

src/util/asmap.h

src/util/bytevectorhash.h

src/node/context.cpp

src/util/insert.h

src/util/readwritefile.h

src/node/peerman_args.cpp

src/node/interface_ui.cpp

src/interfaces/handler.h

src/node/mining_args.h

src/util/hasher.cpp

src/common/init.h

src/kernel/mempool_limits.h

src/common/system.h

src/crypto/sha3.h

src/util/threadinterrupt.cpp

src/node/protocol_version.h

src/util/exception.cpp

src/common/messages.h

src/node/connection_types.cpp

src/util/bip32.h

src/common/license_info.cpp

src/util/stdmutex.h

src/common/run_command.cpp

src/util/check.cpp

src/util/golombrice.h

src/node/types.h

src/node/timeoffsets.h

src/util/readwritefile.cpp

src/util/fastrange.h

src/util/signalinterrupt.h

src/util/task_runner.h

src/util/syserror.cpp

src/common/interfaces.cpp

src/common/types.h

src/util/threadinterrupt.h

src/kernel/chainstatemanager_opts.h

src/node/psbt.h

src/policy/ephemeral_policy.h

src/util/trace.h

src/common/url.cpp

src/kernel/mempool_options.h

src/util/serfloat.cpp

src/kernel/notifications_interface.h

src/node/timeoffsets.cpp

src/node/warnings.cpp

src/util/hash_type.h

src/crypto/hex_base.cpp

src/node/eviction.h

src/util/tokenbucket.h

src/crypto/aes.h

src/common/pcp.h

src/util/feefrac.cpp

src/node/transaction.h

src/util/threadnames.cpp

src/common/signmessage.h

src/util/exec.cpp

src/util/signalinterrupt.cpp

src/clientversion.cpp

src/common/signmessage.cpp

src/compat/assumptions.h

src/compat/byteswap.h

src/deploymentinfo.cpp

src/deploymentinfo.h

src/deploymentstatus.cpp

src/deploymentstatus.h

src/dummywallet.cpp

src/external_signer.h

src/init/bitcoin-gui.cpp

src/init/bitcoin-node.cpp

src/init/bitcoin-qt.cpp

src/init/bitcoin-wallet.cpp

src/init/bitcoind.cpp

src/init/common.h

src/interfaces/init.h

src/interfaces/ipc.h

src/key_io.h

src/logging/categories.h

src/logging/timer.h

src/mapport.h

src/musig.h

src/net_permissions.h

src/netgroup.h

src/netmessagemaker.h

src/node/chainstatemanager_args.cpp

src/node/connection_types.h

src/node/context.h

src/node/interface_ui.h

src/node/mempool_args.cpp

src/node/mining_args.cpp

src/node/minisketchwrapper.cpp

src/node/txreconciliation.h

src/policy/fees/estimator_args.cpp

src/policy/fees/estimator_args.h

src/policy/fees/estimator_man.cpp

src/policy/fees/estimator_man.h

src/policy/packages.h

src/policy/rbf.h

src/policy/truc_policy.h

src/pow.h

src/primitives/block.cpp

src/randomenv.h

src/rest.h

src/script/keyorigin.h

src/script/parsing.cpp

src/script/parsing.h

src/script/script_error.h

src/script/sigcache.cpp

src/script/sigcache.h

src/script/solver.h

src/script/verify_flags.h

src/semaphore_grant.h

src/signet.h

src/span.h

src/support/allocators/secure.h

src/support/allocators/zeroafterfree.h

src/util/tokenpipe.cpp

src/util/translation.h

src/util/vector.h

src/versionbits.h

src/versionbits_impl.h

src/wallet/external_signer_scriptpubkeyman.h

src/wallet/fees.h

src/wallet/load.h

src/wallet/receive.h

src/wallet/rpc/wallet.h

src/wallet/types.h

src/walletinitinterface.h

src/zmq/zmqabstractnotifier.cpp

Independent explanations by MyBitcoinExplorer. Not affiliated with or endorsed by Bitcoin Core. Guides are educational and do not replace the source or its tests.

Bitcoin Core source © its contributors, distributed under the MIT license. Original notices and bundled third-party licenses are retained in the source tree.