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-rw-r--r--src/policy/packages.cpp62
-rw-r--r--src/policy/packages.h10
2 files changed, 72 insertions, 0 deletions
diff --git a/src/policy/packages.cpp b/src/policy/packages.cpp
new file mode 100644
index 0000000000..cfd0539965
--- /dev/null
+++ b/src/policy/packages.cpp
@@ -0,0 +1,62 @@
+// Copyright (c) 2021 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 <consensus/validation.h>
+#include <policy/packages.h>
+#include <primitives/transaction.h>
+#include <uint256.h>
+#include <util/hasher.h>
+
+#include <numeric>
+#include <unordered_set>
+
+bool CheckPackage(const Package& txns, PackageValidationState& state)
+{
+ const unsigned int package_count = txns.size();
+
+ if (package_count > MAX_PACKAGE_COUNT) {
+ return state.Invalid(PackageValidationResult::PCKG_POLICY, "package-too-many-transactions");
+ }
+
+ const int64_t total_size = std::accumulate(txns.cbegin(), txns.cend(), 0,
+ [](int64_t sum, const auto& tx) { return sum + GetVirtualTransactionSize(*tx); });
+ // If the package only contains 1 tx, it's better to report the policy violation on individual tx size.
+ if (package_count > 1 && total_size > MAX_PACKAGE_SIZE * 1000) {
+ return state.Invalid(PackageValidationResult::PCKG_POLICY, "package-too-large");
+ }
+
+ // Require the package to be sorted in order of dependency, i.e. parents appear before children.
+ // An unsorted package will fail anyway on missing-inputs, but it's better to quit earlier and
+ // fail on something less ambiguous (missing-inputs could also be an orphan or trying to
+ // spend nonexistent coins).
+ std::unordered_set<uint256, SaltedTxidHasher> later_txids;
+ std::transform(txns.cbegin(), txns.cend(), std::inserter(later_txids, later_txids.end()),
+ [](const auto& tx) { return tx->GetHash(); });
+ for (const auto& tx : txns) {
+ for (const auto& input : tx->vin) {
+ if (later_txids.find(input.prevout.hash) != later_txids.end()) {
+ // The parent is a subsequent transaction in the package.
+ return state.Invalid(PackageValidationResult::PCKG_POLICY, "package-not-sorted");
+ }
+ }
+ later_txids.erase(tx->GetHash());
+ }
+
+ // Don't allow any conflicting transactions, i.e. spending the same inputs, in a package.
+ std::unordered_set<COutPoint, SaltedOutpointHasher> inputs_seen;
+ for (const auto& tx : txns) {
+ for (const auto& input : tx->vin) {
+ if (inputs_seen.find(input.prevout) != inputs_seen.end()) {
+ // This input is also present in another tx in the package.
+ return state.Invalid(PackageValidationResult::PCKG_POLICY, "conflict-in-package");
+ }
+ }
+ // Batch-add all the inputs for a tx at a time. If we added them 1 at a time, we could
+ // catch duplicate inputs within a single tx. This is a more severe, consensus error,
+ // and we want to report that from CheckTransaction instead.
+ std::transform(tx->vin.cbegin(), tx->vin.cend(), std::inserter(inputs_seen, inputs_seen.end()),
+ [](const auto& input) { return input.prevout; });
+ }
+ return true;
+}
diff --git a/src/policy/packages.h b/src/policy/packages.h
index 4b1463dcb3..6b7ac3e450 100644
--- a/src/policy/packages.h
+++ b/src/policy/packages.h
@@ -6,6 +6,7 @@
#define BITCOIN_POLICY_PACKAGES_H
#include <consensus/validation.h>
+#include <policy/policy.h>
#include <primitives/transaction.h>
#include <vector>
@@ -14,6 +15,7 @@
static constexpr uint32_t MAX_PACKAGE_COUNT{25};
/** Default maximum total virtual size of transactions in a package in KvB. */
static constexpr uint32_t MAX_PACKAGE_SIZE{101};
+static_assert(MAX_PACKAGE_SIZE * WITNESS_SCALE_FACTOR * 1000 >= MAX_STANDARD_TX_WEIGHT);
/** A "reason" why a package was invalid. It may be that one or more of the included
* transactions is invalid or the package itself violates our rules.
@@ -31,4 +33,12 @@ using Package = std::vector<CTransactionRef>;
class PackageValidationState : public ValidationState<PackageValidationResult> {};
+/** Context-free package policy checks:
+ * 1. The number of transactions cannot exceed MAX_PACKAGE_COUNT.
+ * 2. The total virtual size cannot exceed MAX_PACKAGE_SIZE.
+ * 3. If any dependencies exist between transactions, parents must appear before children.
+ * 4. Transactions cannot conflict, i.e., spend the same inputs.
+ */
+bool CheckPackage(const Package& txns, PackageValidationState& state);
+
#endif // BITCOIN_POLICY_PACKAGES_H