diff options
Diffstat (limited to 'src/policy/v3_policy.cpp')
| -rw-r--r-- | src/policy/v3_policy.cpp | 220 |
1 files changed, 220 insertions, 0 deletions
diff --git a/src/policy/v3_policy.cpp b/src/policy/v3_policy.cpp new file mode 100644 index 0000000000..158881aeb9 --- /dev/null +++ b/src/policy/v3_policy.cpp @@ -0,0 +1,220 @@ +// 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/v3_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 PackageV3Checks: 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 PackageV3Checks, 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; + /** nVersion used to check inheritance of v3 and non-v3 */ + decltype(CTransaction::nVersion) 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::nVersion) 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> PackageV3Checks(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(V3_ANCESTOR_LIMIT == 2); + static_assert(V3_DESCENDANT_LIMIT == 2); + + const auto in_package_parents{FindInPackageParents(package, ptx)}; + + // Now we have all ancestors, so we can start checking v3 rules. + if (ptx->nVersion == 3) { + if (mempool_ancestors.size() + in_package_parents.size() + 1 > V3_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 v3 child cannot be too large. + if (vsize > V3_CHILD_MAX_VSIZE) { + return strprintf("v3 child tx %s (wtxid=%s) is too big: %u > %u virtual bytes", + ptx->GetHash().ToString(), ptx->GetWitnessHash().ToString(), + vsize, V3_CHILD_MAX_VSIZE); + } + + const auto parent_info = [&] { + if (mempool_ancestors.size() > 0) { + // There's a parent in the mempool. + auto& mempool_parent = *mempool_ancestors.begin(); + Assume(mempool_parent->GetCountWithDescendants() == 1); + return ParentInfo{mempool_parent->GetTx().GetHash(), + mempool_parent->GetTx().GetWitnessHash(), + mempool_parent->GetTx().nVersion, + /*has_mempool_descendant=*/mempool_parent->GetCountWithDescendants() > 1}; + } else { + // Ancestor must be in the package. Find it. + auto& parent_index = in_package_parents.front(); + auto& package_parent = package.at(parent_index); + return ParentInfo{package_parent->GetHash(), + package_parent->GetWitnessHash(), + package_parent->nVersion, + /*has_mempool_descendant=*/false}; + } + }(); + + // If there is a parent, it must have the right version. + if (parent_info.m_version != 3) { + return strprintf("v3 tx %s (wtxid=%s) cannot spend from non-v3 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 SingleV3Checks) 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()); + } + } + } + + // It shouldn't be possible to have any mempool siblings at this point. SingleV3Checks + // catches mempool siblings. Also, if the package consists of connected transactions, + // any tx having a mempool ancestor would mean the package exceeds ancestor limits. + if (!Assume(!parent_info.m_has_mempool_descendant)) { + return strprintf("tx %u would exceed descendant count limit", parent_info.m_wtxid.ToString()); + } + } + } else { + // Non-v3 transactions cannot have v3 parents. + for (auto it : mempool_ancestors) { + if (it->GetTx().nVersion == 3) { + return strprintf("non-v3 tx %s (wtxid=%s) cannot spend from v3 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)->nVersion == 3) { + return strprintf("non-v3 tx %s (wtxid=%s) cannot spend from v3 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::string> SingleV3Checks(const CTransactionRef& ptx, + const CTxMemPool::setEntries& mempool_ancestors, + const std::set<Txid>& direct_conflicts, + int64_t vsize) +{ + // Check v3 and non-v3 inheritance. + for (const auto& entry : mempool_ancestors) { + if (ptx->nVersion != 3 && entry->GetTx().nVersion == 3) { + return strprintf("non-v3 tx %s (wtxid=%s) cannot spend from v3 tx %s (wtxid=%s)", + ptx->GetHash().ToString(), ptx->GetWitnessHash().ToString(), + entry->GetSharedTx()->GetHash().ToString(), entry->GetSharedTx()->GetWitnessHash().ToString()); + } else if (ptx->nVersion == 3 && entry->GetTx().nVersion != 3) { + return strprintf("v3 tx %s (wtxid=%s) cannot spend from non-v3 tx %s (wtxid=%s)", + ptx->GetHash().ToString(), ptx->GetWitnessHash().ToString(), + entry->GetSharedTx()->GetHash().ToString(), entry->GetSharedTx()->GetWitnessHash().ToString()); + } + } + + // This function is specialized for these limits, and must be reimplemented if they ever change. + static_assert(V3_ANCESTOR_LIMIT == 2); + static_assert(V3_DESCENDANT_LIMIT == 2); + + // The rest of the rules only apply to transactions with nVersion=3. + if (ptx->nVersion != 3) return std::nullopt; + + // Check that V3_ANCESTOR_LIMIT would not be violated, including both in-package and in-mempool. + if (mempool_ancestors.size() + 1 > V3_ANCESTOR_LIMIT) { + return strprintf("tx %s (wtxid=%s) would have too many ancestors", + ptx->GetHash().ToString(), ptx->GetWitnessHash().ToString()); + } + + // Remaining checks only pertain to transactions with unconfirmed ancestors. + if (mempool_ancestors.size() > 0) { + // If this transaction spends V3 parents, it cannot be too large. + if (vsize > V3_CHILD_MAX_VSIZE) { + return strprintf("v3 child tx %s (wtxid=%s) is too big: %u > %u virtual bytes", + ptx->GetHash().ToString(), ptx->GetWitnessHash().ToString(), vsize, V3_CHILD_MAX_VSIZE); + } + + // 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 V3 transaction is a direct child, which makes sense because a V3 + // 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 > V3_DESCENDANT_LIMIT && !child_will_be_replaced) { + return strprintf("tx %u (wtxid=%s) would exceed descendant count limit", + parent_entry->GetSharedTx()->GetHash().ToString(), + parent_entry->GetSharedTx()->GetWitnessHash().ToString()); + } + } + return std::nullopt; +} |