utxo_total_supply.cpp raw
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 <chainparams.h>
6 #include <consensus/amount.h>
7 #include <consensus/merkle.h>
8 #include <kernel/coinstats.h>
9 #include <node/miner.h>
10 #include <primitives/block.h>
11 #include <primitives/transaction.h>
12 #include <script/script.h>
13 #include <sync.h>
14 #include <test/fuzz/FuzzedDataProvider.h>
15 #include <test/fuzz/fuzz.h>
16 #include <test/fuzz/util.h>
17 #include <test/util/mining.h>
18 #include <test/util/random.h>
19 #include <test/util/setup_common.h>
20 #include <test/util/time.h>
21 #include <txdb.h>
22 #include <uint256.h>
23 #include <util/check.h>
24 #include <validation.h>
25
26 #include <cstddef>
27 #include <cstdint>
28 #include <functional>
29 #include <memory>
30 #include <optional>
31 #include <utility>
32 #include <vector>
33
34 FUZZ_TARGET(utxo_total_supply)
35 {
36 SeedRandomStateForTest(SeedRand::ZEROS);
37 FuzzedDataProvider fuzzed_data_provider(buffer.data(), buffer.size());
38 FakeNodeClock clock{ConsumeTime(fuzzed_data_provider, /*min=*/1296688602)}; // regtest genesis block timestamp
39 /** The testing setup that creates a chainman only (no chainstate) */
40 ChainTestingSetup test_setup{
41 ChainType::REGTEST,
42 {
43 .extra_args = {
44 "-testactivationheight=bip34@2",
45 },
46 },
47 };
48 // Create chainstate
49 test_setup.LoadVerifyActivateChainstate();
50 auto& node{test_setup.m_node};
51 auto& chainman{*Assert(test_setup.m_node.chainman)};
52
53 const auto ActiveHeight = [&]() {
54 LOCK(chainman.GetMutex());
55 return chainman.ActiveHeight();
56 };
57 const auto PrepareNextBlock = [&]() {
58 // Use OP_FALSE to avoid BIP30 check from hitting early
59 auto block = PrepareBlock(node, {
60 .coinbase_output_script = CScript() << OP_FALSE,
61 });
62 // Replace OP_FALSE with OP_TRUE
63 {
64 CMutableTransaction tx{*block->vtx.back()};
65 tx.nLockTime = 0; // Use the same nLockTime for all as we want to duplicate one of them.
66 tx.vout.at(0).scriptPubKey = CScript{} << OP_TRUE;
67 block->vtx.back() = MakeTransactionRef(tx);
68 }
69 return block;
70 };
71
72 /** The block template this fuzzer is working on */
73 auto current_block = PrepareNextBlock();
74 /** Append-only set of tx outpoints, entries are not removed when spent */
75 std::vector<std::pair<COutPoint, CTxOut>> txos;
76 /** The utxo stats at the chain tip */
77 kernel::CCoinsStats utxo_stats;
78 /** The total amount of coins in the utxo set */
79 CAmount circulation{0};
80
81
82 // Store the tx out in the txo map
83 const auto StoreLastTxo = [&]() {
84 // get last tx
85 const CTransaction& tx = *current_block->vtx.back();
86 // get last out
87 const uint32_t i = tx.vout.size() - 1;
88 // store it
89 txos.emplace_back(COutPoint{tx.GetHash(), i}, tx.vout.at(i));
90 if (current_block->vtx.size() == 1 && tx.vout.at(i).scriptPubKey[0] == OP_RETURN) {
91 // also store coinbase
92 const uint32_t i = tx.vout.size() - 2;
93 txos.emplace_back(COutPoint{tx.GetHash(), i}, tx.vout.at(i));
94 }
95 };
96 const auto AppendRandomTxo = [&](CMutableTransaction& tx) {
97 const auto& txo = txos.at(fuzzed_data_provider.ConsumeIntegralInRange<size_t>(0, txos.size() - 1));
98 tx.vin.emplace_back(txo.first);
99 tx.vout.emplace_back(txo.second.nValue, txo.second.scriptPubKey); // "Forward" coin with no fee
100 };
101 const auto UpdateUtxoStats = [&](bool wipe_cache) {
102 LOCK(chainman.GetMutex());
103 chainman.ActiveChainstate().ForceFlushStateToDisk(wipe_cache);
104 utxo_stats = std::move(
105 *Assert(kernel::ComputeUTXOStats(kernel::CoinStatsHashType::NONE, &chainman.ActiveChainstate().CoinsDB(), chainman.m_blockman, {})));
106 // Check that miner can't print more money than they are allowed to
107 assert(circulation == utxo_stats.total_amount);
108 };
109
110
111 // Update internal state to chain tip
112 StoreLastTxo();
113 UpdateUtxoStats(/*wipe_cache=*/fuzzed_data_provider.ConsumeBool());
114 assert(ActiveHeight() == 0);
115 // Get at which height we duplicate the coinbase
116 // Assuming that the fuzzer will mine relatively short chains (less than 200 blocks), we want the duplicate coinbase to be not too high.
117 // Up to 300 seems reasonable.
118 int64_t duplicate_coinbase_height = fuzzed_data_provider.ConsumeIntegralInRange(0, 300);
119 // Avoid bad-cb-length error at heights <= 16. Pad the BIP34-encoded height
120 // with OP_0 to satisfy the minimum 2-byte coinbase scriptSig length.
121 CScript duplicate_coinbase_script = CScript() << duplicate_coinbase_height;
122 if (duplicate_coinbase_height <= 16) {
123 duplicate_coinbase_script << OP_0;
124 }
125 // Mine the first block with this duplicate
126 current_block = PrepareNextBlock();
127 StoreLastTxo();
128
129 {
130 // Create duplicate (CScript should match exact format as in CreateNewBlock)
131 CMutableTransaction tx{*current_block->vtx.front()};
132 tx.vin.at(0).scriptSig = duplicate_coinbase_script;
133
134 // Mine block and create next block template
135 current_block->vtx.front() = MakeTransactionRef(tx);
136 }
137 current_block->hashMerkleRoot = BlockMerkleRoot(*current_block);
138 assert(!MineBlock(node, current_block).IsNull());
139 circulation += GetBlockSubsidy(ActiveHeight(), Params().GetConsensus());
140
141 assert(ActiveHeight() == 1);
142 UpdateUtxoStats(/*wipe_cache=*/fuzzed_data_provider.ConsumeBool());
143 current_block = PrepareNextBlock();
144 StoreLastTxo();
145
146 // Limit to avoid timeout, but enough to cover duplicate_coinbase_height
147 // and CVE-2018-17144.
148 LIMITED_WHILE(fuzzed_data_provider.remaining_bytes(), 2'00)
149 {
150 CallOneOf(
151 fuzzed_data_provider,
152 [&] {
153 // Append an input-output pair to the last tx in the current block
154 CMutableTransaction tx{*current_block->vtx.back()};
155 AppendRandomTxo(tx);
156 current_block->vtx.back() = MakeTransactionRef(tx);
157 StoreLastTxo();
158 },
159 [&] {
160 // Append a tx to the list of txs in the current block
161 CMutableTransaction tx{};
162 AppendRandomTxo(tx);
163 current_block->vtx.push_back(MakeTransactionRef(tx));
164 StoreLastTxo();
165 },
166 [&] {
167 // Append the current block to the active chain
168 node::RegenerateCommitments(*current_block, chainman);
169 const bool was_valid = !MineBlock(node, current_block).IsNull();
170
171 const uint256 prev_hash_serialized{utxo_stats.hashSerialized};
172 if (was_valid) {
173 if (duplicate_coinbase_height == ActiveHeight()) {
174 // we mined the duplicate coinbase
175 assert(current_block->vtx.at(0)->vin.at(0).scriptSig == duplicate_coinbase_script);
176 }
177
178 circulation += GetBlockSubsidy(ActiveHeight(), Params().GetConsensus());
179 }
180
181 UpdateUtxoStats(/*wipe_cache=*/fuzzed_data_provider.ConsumeBool());
182
183 if (!was_valid) {
184 // utxo stats must not change
185 assert(prev_hash_serialized == utxo_stats.hashSerialized);
186 }
187
188 current_block = PrepareNextBlock();
189 StoreLastTxo();
190 });
191 }
192 }
193