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1 : : // Copyright (c) 2022 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 <policy/truc_policy.h>
6 : :
7 : : #include <coins.h>
8 : : #include <consensus/amount.h>
9 : : #include <logging.h>
10 : : #include <tinyformat.h>
11 : : #include <util/check.h>
12 : :
13 : : #include <algorithm>
14 : : #include <numeric>
15 : : #include <vector>
16 : :
17 : : /** Helper for PackageTRUCChecks: Returns a vector containing the indices of transactions (within
18 : : * package) that are direct parents of ptx. */
19 : 27 : std::vector<size_t> FindInPackageParents(const Package& package, const CTransactionRef& ptx)
20 : : {
21 : 27 : std::vector<size_t> in_package_parents;
22 : :
23 : 27 : std::set<Txid> possible_parents;
24 [ + + ]: 170 : for (auto &input : ptx->vin) {
25 [ + - ]: 143 : possible_parents.insert(input.prevout.hash);
26 : : }
27 : :
28 [ + - ]: 52 : for (size_t i{0}; i < package.size(); ++i) {
29 [ + - ]: 52 : const auto& tx = package.at(i);
30 : : // We assume the package is sorted, so that we don't need to continue
31 : : // looking past the transaction itself.
32 [ + + ]: 52 : if (&(*tx) == &(*ptx)) break;
33 [ + + ]: 25 : if (possible_parents.count(tx->GetHash())) {
34 [ + - ]: 23 : in_package_parents.push_back(i);
35 : : }
36 : : }
37 : 27 : return in_package_parents;
38 : 27 : }
39 : :
40 : : /** Helper for PackageTRUCChecks, storing info for a mempool or package parent. */
41 : : struct ParentInfo {
42 : : /** Txid used to identify this parent by prevout */
43 : : const Txid& m_txid;
44 : : /** Wtxid used for debug string */
45 : : const Wtxid& m_wtxid;
46 : : /** version used to check inheritance of TRUC and non-TRUC */
47 : : decltype(CTransaction::version) m_version;
48 : : /** If parent is in mempool, whether it has any descendants in mempool. */
49 : : bool m_has_mempool_descendant;
50 : :
51 : : ParentInfo() = delete;
52 : 7 : ParentInfo(const Txid& txid, const Wtxid& wtxid, decltype(CTransaction::version) version, bool has_mempool_descendant) :
53 : 7 : m_txid{txid}, m_wtxid{wtxid}, m_version{version},
54 : 7 : m_has_mempool_descendant{has_mempool_descendant}
55 : 1 : {}
56 : : };
57 : :
58 : 27 : std::optional<std::string> PackageTRUCChecks(const CTransactionRef& ptx, int64_t vsize,
59 : : const Package& package,
60 : : const CTxMemPool::setEntries& mempool_ancestors)
61 : : {
62 : : // This function is specialized for these limits, and must be reimplemented if they ever change.
63 : 27 : static_assert(TRUC_ANCESTOR_LIMIT == 2);
64 : 27 : static_assert(TRUC_DESCENDANT_LIMIT == 2);
65 : :
66 : 27 : const auto in_package_parents{FindInPackageParents(package, ptx)};
67 : :
68 : : // Now we have all ancestors, so we can start checking TRUC rules.
69 [ + + ]: 27 : if (ptx->version == TRUC_VERSION) {
70 : : // SingleTRUCChecks should have checked this already.
71 [ + - - + ]: 11 : if (!Assume(vsize <= TRUC_MAX_VSIZE)) {
72 [ # # ]: 0 : return strprintf("version=3 tx %s (wtxid=%s) is too big: %u > %u virtual bytes",
73 [ # # # # : 0 : ptx->GetHash().ToString(), ptx->GetWitnessHash().ToString(), vsize, TRUC_MAX_VSIZE);
# # ]
74 : : }
75 : :
76 [ + + ]: 11 : if (mempool_ancestors.size() + in_package_parents.size() + 1 > TRUC_ANCESTOR_LIMIT) {
77 [ + - ]: 4 : return strprintf("tx %s (wtxid=%s) would have too many ancestors",
78 [ + - + - : 6 : ptx->GetHash().ToString(), ptx->GetWitnessHash().ToString());
+ - ]
79 : : }
80 : :
81 [ + - ]: 9 : const bool has_parent{mempool_ancestors.size() + in_package_parents.size() > 0};
82 [ + - ]: 9 : if (has_parent) {
83 : : // A TRUC child cannot be too large.
84 [ + + ]: 9 : if (vsize > TRUC_CHILD_MAX_VSIZE) {
85 [ + - ]: 4 : return strprintf("version=3 child tx %s (wtxid=%s) is too big: %u > %u virtual bytes",
86 [ + - + - : 4 : ptx->GetHash().ToString(), ptx->GetWitnessHash().ToString(),
+ - ]
87 : 2 : vsize, TRUC_CHILD_MAX_VSIZE);
88 : : }
89 : :
90 : : // Exactly 1 parent exists, either in mempool or package. Find it.
91 : 14 : const auto parent_info = [&] {
92 [ + + ]: 7 : if (mempool_ancestors.size() > 0) {
93 : 1 : auto& mempool_parent = *mempool_ancestors.begin();
94 : 1 : return ParentInfo{mempool_parent->GetTx().GetHash(),
95 : 1 : mempool_parent->GetTx().GetWitnessHash(),
96 : 1 : mempool_parent->GetTx().version,
97 : 1 : /*has_mempool_descendant=*/mempool_parent->GetCountWithDescendants() > 1};
98 : : } else {
99 : 6 : auto& parent_index = in_package_parents.front();
100 : 6 : auto& package_parent = package.at(parent_index);
101 : 6 : return ParentInfo{package_parent->GetHash(),
102 : : package_parent->GetWitnessHash(),
103 : 6 : package_parent->version,
104 : 6 : /*has_mempool_descendant=*/false};
105 : : }
106 [ + - ]: 7 : }();
107 : :
108 : : // If there is a parent, it must have the right version.
109 [ + + ]: 7 : if (parent_info.m_version != TRUC_VERSION) {
110 : 2 : return strprintf("version=3 tx %s (wtxid=%s) cannot spend from non-version=3 tx %s (wtxid=%s)",
111 [ + - + - : 4 : ptx->GetHash().ToString(), ptx->GetWitnessHash().ToString(),
+ - ]
112 [ + - + - : 6 : parent_info.m_txid.ToString(), parent_info.m_wtxid.ToString());
+ - ]
113 : : }
114 : :
115 [ + + ]: 15 : for (const auto& package_tx : package) {
116 : : // Skip same tx.
117 [ + + ]: 12 : if (&(*package_tx) == &(*ptx)) continue;
118 : :
119 [ + + ]: 14 : for (auto& input : package_tx->vin) {
120 : : // Fail if we find another tx with the same parent. We don't check whether the
121 : : // sibling is to-be-replaced (done in SingleTRUCChecks) because these transactions
122 : : // are within the same package.
123 [ + + ]: 8 : if (input.prevout.hash == parent_info.m_txid) {
124 : 1 : return strprintf("tx %s (wtxid=%s) would exceed descendant count limit",
125 [ + - ]: 2 : parent_info.m_txid.ToString(),
126 [ + - + - ]: 3 : parent_info.m_wtxid.ToString());
127 : : }
128 : :
129 : : // This tx can't have both a parent and an in-package child.
130 [ + + ]: 7 : if (input.prevout.hash == ptx->GetHash()) {
131 [ + - ]: 2 : return strprintf("tx %s (wtxid=%s) would have too many ancestors",
132 [ + - + - : 3 : package_tx->GetHash().ToString(), package_tx->GetWitnessHash().ToString());
+ - ]
133 : : }
134 : : }
135 : : }
136 : :
137 [ - + ]: 3 : if (parent_info.m_has_mempool_descendant) {
138 : 0 : return strprintf("tx %s (wtxid=%s) would exceed descendant count limit",
139 [ # # # # : 0 : parent_info.m_txid.ToString(), parent_info.m_wtxid.ToString());
# # ]
140 : : }
141 : : }
142 : : } else {
143 : : // Non-TRUC transactions cannot have TRUC parents.
144 [ + + ]: 19 : for (auto it : mempool_ancestors) {
145 [ + + ]: 4 : if (it->GetTx().version == TRUC_VERSION) {
146 [ + - ]: 2 : return strprintf("non-version=3 tx %s (wtxid=%s) cannot spend from version=3 tx %s (wtxid=%s)",
147 [ + - + - : 2 : ptx->GetHash().ToString(), ptx->GetWitnessHash().ToString(),
+ - ]
148 [ + - + - : 7 : it->GetSharedTx()->GetHash().ToString(), it->GetSharedTx()->GetWitnessHash().ToString());
+ - + - +
- + - +
- ]
149 : : }
150 : : }
151 [ + + ]: 22 : for (const auto& index: in_package_parents) {
152 [ + - + + ]: 9 : if (package.at(index)->version == TRUC_VERSION) {
153 : 2 : return strprintf("non-version=3 tx %s (wtxid=%s) cannot spend from version=3 tx %s (wtxid=%s)",
154 [ + - + - ]: 4 : ptx->GetHash().ToString(),
155 [ + - + - ]: 4 : ptx->GetWitnessHash().ToString(),
156 [ + - + - ]: 4 : package.at(index)->GetHash().ToString(),
157 [ + - + - : 6 : package.at(index)->GetWitnessHash().ToString());
+ - ]
158 : : }
159 : : }
160 : : }
161 : 16 : return std::nullopt;
162 : 27 : }
163 : :
164 : 126 : std::optional<std::pair<std::string, CTransactionRef>> SingleTRUCChecks(const CTransactionRef& ptx,
165 : : const CTxMemPool::setEntries& mempool_ancestors,
166 : : const std::set<Txid>& direct_conflicts,
167 : : int64_t vsize)
168 : : {
169 : : // Check TRUC and non-TRUC inheritance.
170 [ + + ]: 154 : for (const auto& entry : mempool_ancestors) {
171 [ + + + + ]: 32 : if (ptx->version != TRUC_VERSION && entry->GetTx().version == TRUC_VERSION) {
172 : 4 : return std::make_pair(strprintf("non-version=3 tx %s (wtxid=%s) cannot spend from version=3 tx %s (wtxid=%s)",
173 [ + - + - : 4 : ptx->GetHash().ToString(), ptx->GetWitnessHash().ToString(),
+ - ]
174 [ + - + - : 12 : entry->GetSharedTx()->GetHash().ToString(), entry->GetSharedTx()->GetWitnessHash().ToString()),
+ - + - +
- + - +
- ]
175 [ + - ]: 4 : nullptr);
176 [ + + + + ]: 30 : } else if (ptx->version == TRUC_VERSION && entry->GetTx().version != TRUC_VERSION) {
177 : 4 : return std::make_pair(strprintf("version=3 tx %s (wtxid=%s) cannot spend from non-version=3 tx %s (wtxid=%s)",
178 [ + - + - : 4 : ptx->GetHash().ToString(), ptx->GetWitnessHash().ToString(),
+ - ]
179 [ + - + - : 12 : entry->GetSharedTx()->GetHash().ToString(), entry->GetSharedTx()->GetWitnessHash().ToString()),
+ - + - +
- + - +
- ]
180 [ + - ]: 4 : nullptr);
181 : : }
182 : : }
183 : :
184 : : // This function is specialized for these limits, and must be reimplemented if they ever change.
185 : 122 : static_assert(TRUC_ANCESTOR_LIMIT == 2);
186 : 122 : static_assert(TRUC_DESCENDANT_LIMIT == 2);
187 : :
188 : : // The rest of the rules only apply to transactions with version=3.
189 [ + + ]: 122 : if (ptx->version != TRUC_VERSION) return std::nullopt;
190 : :
191 [ - + ]: 11 : if (vsize > TRUC_MAX_VSIZE) {
192 : 0 : return std::make_pair(strprintf("version=3 tx %s (wtxid=%s) is too big: %u > %u virtual bytes",
193 [ # # # # ]: 0 : ptx->GetHash().ToString(), ptx->GetWitnessHash().ToString(), vsize, TRUC_MAX_VSIZE),
194 : 0 : nullptr);
195 : : }
196 : :
197 : : // Check that TRUC_ANCESTOR_LIMIT would not be violated.
198 [ + + ]: 11 : if (mempool_ancestors.size() + 1 > TRUC_ANCESTOR_LIMIT) {
199 : 4 : return std::make_pair(strprintf("tx %s (wtxid=%s) would have too many ancestors",
200 [ + - + - ]: 4 : ptx->GetHash().ToString(), ptx->GetWitnessHash().ToString()),
201 : 4 : nullptr);
202 : : }
203 : :
204 : : // Remaining checks only pertain to transactions with unconfirmed ancestors.
205 [ + - ]: 9 : if (mempool_ancestors.size() > 0) {
206 : : // If this transaction spends TRUC parents, it cannot be too large.
207 [ + + ]: 9 : if (vsize > TRUC_CHILD_MAX_VSIZE) {
208 : 4 : return std::make_pair(strprintf("version=3 child tx %s (wtxid=%s) is too big: %u > %u virtual bytes",
209 [ + - + - ]: 4 : ptx->GetHash().ToString(), ptx->GetWitnessHash().ToString(), vsize, TRUC_CHILD_MAX_VSIZE),
210 : 4 : nullptr);
211 : : }
212 : :
213 : : // Check the descendant counts of in-mempool ancestors.
214 [ + + ]: 7 : const auto& parent_entry = *mempool_ancestors.begin();
215 : : // If there are any ancestors, this is the only child allowed. The parent cannot have any
216 : : // other descendants. We handle the possibility of multiple children as that case is
217 : : // possible through a reorg.
218 [ + + ]: 7 : const auto& children = parent_entry->GetMemPoolChildrenConst();
219 : : // Don't double-count a transaction that is going to be replaced. This logic assumes that
220 : : // any descendant of the TRUC transaction is a direct child, which makes sense because a
221 : : // TRUC transaction can only have 1 descendant.
222 [ + + + + ]: 11 : const bool child_will_be_replaced = !children.empty() &&
223 : 4 : std::any_of(children.cbegin(), children.cend(),
224 : 5 : [&direct_conflicts](const CTxMemPoolEntry& child){return direct_conflicts.count(child.GetTx().GetHash()) > 0;});
225 [ + + + + ]: 7 : if (parent_entry->GetCountWithDescendants() + 1 > TRUC_DESCENDANT_LIMIT && !child_will_be_replaced) {
226 : : // Allow sibling eviction for TRUC transaction: if another child already exists, even if
227 : : // we don't conflict inputs with it, consider evicting it under RBF rules. We rely on TRUC rules
228 : : // only permitting 1 descendant, as otherwise we would need to have logic for deciding
229 : : // which descendant to evict. Skip if this isn't true, e.g. if the transaction has
230 : : // multiple children or the sibling also has descendants due to a reorg.
231 [ + + - + ]: 3 : const bool consider_sibling_eviction{parent_entry->GetCountWithDescendants() == 2 &&
232 [ - + ]: 1 : children.begin()->get().GetCountWithAncestors() == 2};
233 : :
234 : : // Return the sibling if its eviction can be considered. Provide the "descendant count
235 : : // limit" string either way, as the caller may decide not to do sibling eviction.
236 [ + - ]: 9 : return std::make_pair(strprintf("tx %u (wtxid=%s) would exceed descendant count limit",
237 [ + - + - : 12 : parent_entry->GetSharedTx()->GetHash().ToString(),
+ - + - ]
238 [ + - + - : 12 : parent_entry->GetSharedTx()->GetWitnessHash().ToString()),
+ - + - ]
239 [ + - + - ]: 10 : consider_sibling_eviction ? children.begin()->get().GetSharedTx() : nullptr);
240 : : }
241 : : }
242 : 4 : return std::nullopt;
243 : : }
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