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-rw-r--r--src/policy/truc_policy.cpp243
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diff --git a/src/policy/truc_policy.cpp b/src/policy/truc_policy.cpp
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+// Copyright (c) 2022 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <policy/truc_policy.h>
+
+#include <coins.h>
+#include <consensus/amount.h>
+#include <logging.h>
+#include <tinyformat.h>
+#include <util/check.h>
+
+#include <algorithm>
+#include <numeric>
+#include <vector>
+
+/** Helper for PackageTRUCChecks: Returns a vector containing the indices of transactions (within
+ * package) that are direct parents of ptx. */
+std::vector<size_t> FindInPackageParents(const Package& package, const CTransactionRef& ptx)
+{
+ std::vector<size_t> in_package_parents;
+
+ std::set<Txid> possible_parents;
+ for (auto &input : ptx->vin) {
+ possible_parents.insert(input.prevout.hash);
+ }
+
+ for (size_t i{0}; i < package.size(); ++i) {
+ const auto& tx = package.at(i);
+ // We assume the package is sorted, so that we don't need to continue
+ // looking past the transaction itself.
+ if (&(*tx) == &(*ptx)) break;
+ if (possible_parents.count(tx->GetHash())) {
+ in_package_parents.push_back(i);
+ }
+ }
+ return in_package_parents;
+}
+
+/** Helper for PackageTRUCChecks, storing info for a mempool or package parent. */
+struct ParentInfo {
+ /** Txid used to identify this parent by prevout */
+ const Txid& m_txid;
+ /** Wtxid used for debug string */
+ const Wtxid& m_wtxid;
+ /** version used to check inheritance of TRUC and non-TRUC */
+ decltype(CTransaction::version) m_version;
+ /** If parent is in mempool, whether it has any descendants in mempool. */
+ bool m_has_mempool_descendant;
+
+ ParentInfo() = delete;
+ ParentInfo(const Txid& txid, const Wtxid& wtxid, decltype(CTransaction::version) version, bool has_mempool_descendant) :
+ m_txid{txid}, m_wtxid{wtxid}, m_version{version},
+ m_has_mempool_descendant{has_mempool_descendant}
+ {}
+};
+
+std::optional<std::string> PackageTRUCChecks(const CTransactionRef& ptx, int64_t vsize,
+ const Package& package,
+ const CTxMemPool::setEntries& mempool_ancestors)
+{
+ // This function is specialized for these limits, and must be reimplemented if they ever change.
+ static_assert(TRUC_ANCESTOR_LIMIT == 2);
+ static_assert(TRUC_DESCENDANT_LIMIT == 2);
+
+ const auto in_package_parents{FindInPackageParents(package, ptx)};
+
+ // Now we have all ancestors, so we can start checking TRUC rules.
+ if (ptx->version == TRUC_VERSION) {
+ // SingleTRUCChecks should have checked this already.
+ if (!Assume(vsize <= TRUC_MAX_VSIZE)) {
+ return strprintf("version=3 tx %s (wtxid=%s) is too big: %u > %u virtual bytes",
+ ptx->GetHash().ToString(), ptx->GetWitnessHash().ToString(), vsize, TRUC_MAX_VSIZE);
+ }
+
+ if (mempool_ancestors.size() + in_package_parents.size() + 1 > TRUC_ANCESTOR_LIMIT) {
+ return strprintf("tx %s (wtxid=%s) would have too many ancestors",
+ ptx->GetHash().ToString(), ptx->GetWitnessHash().ToString());
+ }
+
+ const bool has_parent{mempool_ancestors.size() + in_package_parents.size() > 0};
+ if (has_parent) {
+ // A TRUC child cannot be too large.
+ if (vsize > TRUC_CHILD_MAX_VSIZE) {
+ return strprintf("version=3 child tx %s (wtxid=%s) is too big: %u > %u virtual bytes",
+ ptx->GetHash().ToString(), ptx->GetWitnessHash().ToString(),
+ vsize, TRUC_CHILD_MAX_VSIZE);
+ }
+
+ // Exactly 1 parent exists, either in mempool or package. Find it.
+ const auto parent_info = [&] {
+ if (mempool_ancestors.size() > 0) {
+ auto& mempool_parent = *mempool_ancestors.begin();
+ return ParentInfo{mempool_parent->GetTx().GetHash(),
+ mempool_parent->GetTx().GetWitnessHash(),
+ mempool_parent->GetTx().version,
+ /*has_mempool_descendant=*/mempool_parent->GetCountWithDescendants() > 1};
+ } else {
+ auto& parent_index = in_package_parents.front();
+ auto& package_parent = package.at(parent_index);
+ return ParentInfo{package_parent->GetHash(),
+ package_parent->GetWitnessHash(),
+ package_parent->version,
+ /*has_mempool_descendant=*/false};
+ }
+ }();
+
+ // If there is a parent, it must have the right version.
+ if (parent_info.m_version != TRUC_VERSION) {
+ return strprintf("version=3 tx %s (wtxid=%s) cannot spend from non-version=3 tx %s (wtxid=%s)",
+ ptx->GetHash().ToString(), ptx->GetWitnessHash().ToString(),
+ parent_info.m_txid.ToString(), parent_info.m_wtxid.ToString());
+ }
+
+ for (const auto& package_tx : package) {
+ // Skip same tx.
+ if (&(*package_tx) == &(*ptx)) continue;
+
+ for (auto& input : package_tx->vin) {
+ // Fail if we find another tx with the same parent. We don't check whether the
+ // sibling is to-be-replaced (done in SingleTRUCChecks) because these transactions
+ // are within the same package.
+ if (input.prevout.hash == parent_info.m_txid) {
+ return strprintf("tx %s (wtxid=%s) would exceed descendant count limit",
+ parent_info.m_txid.ToString(),
+ parent_info.m_wtxid.ToString());
+ }
+
+ // This tx can't have both a parent and an in-package child.
+ if (input.prevout.hash == ptx->GetHash()) {
+ return strprintf("tx %s (wtxid=%s) would have too many ancestors",
+ package_tx->GetHash().ToString(), package_tx->GetWitnessHash().ToString());
+ }
+ }
+ }
+
+ if (parent_info.m_has_mempool_descendant) {
+ return strprintf("tx %s (wtxid=%s) would exceed descendant count limit",
+ parent_info.m_txid.ToString(), parent_info.m_wtxid.ToString());
+ }
+ }
+ } else {
+ // Non-TRUC transactions cannot have TRUC parents.
+ for (auto it : mempool_ancestors) {
+ if (it->GetTx().version == TRUC_VERSION) {
+ return strprintf("non-version=3 tx %s (wtxid=%s) cannot spend from version=3 tx %s (wtxid=%s)",
+ ptx->GetHash().ToString(), ptx->GetWitnessHash().ToString(),
+ it->GetSharedTx()->GetHash().ToString(), it->GetSharedTx()->GetWitnessHash().ToString());
+ }
+ }
+ for (const auto& index: in_package_parents) {
+ if (package.at(index)->version == TRUC_VERSION) {
+ return strprintf("non-version=3 tx %s (wtxid=%s) cannot spend from version=3 tx %s (wtxid=%s)",
+ ptx->GetHash().ToString(),
+ ptx->GetWitnessHash().ToString(),
+ package.at(index)->GetHash().ToString(),
+ package.at(index)->GetWitnessHash().ToString());
+ }
+ }
+ }
+ return std::nullopt;
+}
+
+std::optional<std::pair<std::string, CTransactionRef>> SingleTRUCChecks(const CTransactionRef& ptx,
+ const CTxMemPool::setEntries& mempool_ancestors,
+ const std::set<Txid>& direct_conflicts,
+ int64_t vsize)
+{
+ // Check TRUC and non-TRUC inheritance.
+ for (const auto& entry : mempool_ancestors) {
+ if (ptx->version != TRUC_VERSION && entry->GetTx().version == TRUC_VERSION) {
+ return std::make_pair(strprintf("non-version=3 tx %s (wtxid=%s) cannot spend from version=3 tx %s (wtxid=%s)",
+ ptx->GetHash().ToString(), ptx->GetWitnessHash().ToString(),
+ entry->GetSharedTx()->GetHash().ToString(), entry->GetSharedTx()->GetWitnessHash().ToString()),
+ nullptr);
+ } else if (ptx->version == TRUC_VERSION && entry->GetTx().version != TRUC_VERSION) {
+ return std::make_pair(strprintf("version=3 tx %s (wtxid=%s) cannot spend from non-version=3 tx %s (wtxid=%s)",
+ ptx->GetHash().ToString(), ptx->GetWitnessHash().ToString(),
+ entry->GetSharedTx()->GetHash().ToString(), entry->GetSharedTx()->GetWitnessHash().ToString()),
+ nullptr);
+ }
+ }
+
+ // This function is specialized for these limits, and must be reimplemented if they ever change.
+ static_assert(TRUC_ANCESTOR_LIMIT == 2);
+ static_assert(TRUC_DESCENDANT_LIMIT == 2);
+
+ // The rest of the rules only apply to transactions with version=3.
+ if (ptx->version != TRUC_VERSION) return std::nullopt;
+
+ if (vsize > TRUC_MAX_VSIZE) {
+ return std::make_pair(strprintf("version=3 tx %s (wtxid=%s) is too big: %u > %u virtual bytes",
+ ptx->GetHash().ToString(), ptx->GetWitnessHash().ToString(), vsize, TRUC_MAX_VSIZE),
+ nullptr);
+ }
+
+ // Check that TRUC_ANCESTOR_LIMIT would not be violated.
+ if (mempool_ancestors.size() + 1 > TRUC_ANCESTOR_LIMIT) {
+ return std::make_pair(strprintf("tx %s (wtxid=%s) would have too many ancestors",
+ ptx->GetHash().ToString(), ptx->GetWitnessHash().ToString()),
+ nullptr);
+ }
+
+ // Remaining checks only pertain to transactions with unconfirmed ancestors.
+ if (mempool_ancestors.size() > 0) {
+ // If this transaction spends TRUC parents, it cannot be too large.
+ if (vsize > TRUC_CHILD_MAX_VSIZE) {
+ return std::make_pair(strprintf("version=3 child tx %s (wtxid=%s) is too big: %u > %u virtual bytes",
+ ptx->GetHash().ToString(), ptx->GetWitnessHash().ToString(), vsize, TRUC_CHILD_MAX_VSIZE),
+ nullptr);
+ }
+
+ // Check the descendant counts of in-mempool ancestors.
+ const auto& parent_entry = *mempool_ancestors.begin();
+ // If there are any ancestors, this is the only child allowed. The parent cannot have any
+ // other descendants. We handle the possibility of multiple children as that case is
+ // possible through a reorg.
+ const auto& children = parent_entry->GetMemPoolChildrenConst();
+ // Don't double-count a transaction that is going to be replaced. This logic assumes that
+ // any descendant of the TRUC transaction is a direct child, which makes sense because a
+ // TRUC transaction can only have 1 descendant.
+ const bool child_will_be_replaced = !children.empty() &&
+ std::any_of(children.cbegin(), children.cend(),
+ [&direct_conflicts](const CTxMemPoolEntry& child){return direct_conflicts.count(child.GetTx().GetHash()) > 0;});
+ if (parent_entry->GetCountWithDescendants() + 1 > TRUC_DESCENDANT_LIMIT && !child_will_be_replaced) {
+ // Allow sibling eviction for TRUC transaction: if another child already exists, even if
+ // we don't conflict inputs with it, consider evicting it under RBF rules. We rely on TRUC rules
+ // only permitting 1 descendant, as otherwise we would need to have logic for deciding
+ // which descendant to evict. Skip if this isn't true, e.g. if the transaction has
+ // multiple children or the sibling also has descendants due to a reorg.
+ const bool consider_sibling_eviction{parent_entry->GetCountWithDescendants() == 2 &&
+ children.begin()->get().GetCountWithAncestors() == 2};
+
+ // Return the sibling if its eviction can be considered. Provide the "descendant count
+ // limit" string either way, as the caller may decide not to do sibling eviction.
+ return std::make_pair(strprintf("tx %u (wtxid=%s) would exceed descendant count limit",
+ parent_entry->GetSharedTx()->GetHash().ToString(),
+ parent_entry->GetSharedTx()->GetWitnessHash().ToString()),
+ consider_sibling_eviction ? children.begin()->get().GetSharedTx() : nullptr);
+ }
+ }
+ return std::nullopt;
+}