diff options
| -rw-r--r-- | doc/policy/packages.md | 45 | ||||
| -rw-r--r-- | src/test/fuzz/tx_pool.cpp | 14 | ||||
| -rw-r--r-- | src/test/txpackage_tests.cpp | 227 | ||||
| -rw-r--r-- | src/validation.cpp | 89 | ||||
| -rw-r--r-- | src/validation.h | 8 |
5 files changed, 362 insertions, 21 deletions
diff --git a/doc/policy/packages.md b/doc/policy/packages.md index 7f7fbe18cd..f2a3d6517e 100644 --- a/doc/policy/packages.md +++ b/doc/policy/packages.md @@ -72,3 +72,48 @@ test accepts): a competing package or transaction with a mutated witness, even though the two same-txid-different-witness transactions are conflicting and cannot replace each other, the honest package should still be considered for acceptance. + +### Package Fees and Feerate + +*Package Feerate* is the total modified fees (base fees + any fee delta from +`prioritisetransaction`) divided by the total virtual size of all transactions in the package. +If any transactions in the package are already in the mempool, they are not submitted again +("deduplicated") and are thus excluded from this calculation. + +To meet the two feerate requirements of a mempool, i.e., the pre-configured minimum relay feerate +(`minRelayTxFee`) and the dynamic mempool minimum feerate, the total package feerate is used instead +of the individual feerate. The individual transactions are allowed to be below the feerate +requirements if the package meets the feerate requirements. For example, the parent(s) in the +package can pay no fees but be paid for by the child. + +*Rationale*: This can be thought of as "CPFP within a package," solving the issue of a parent not +meeting minimum fees on its own. This would allow contracting applications to adjust their fees at +broadcast time instead of overshooting or risking becoming stuck or pinned. + +*Rationale*: It would be incorrect to use the fees of transactions that are already in the mempool, as +we do not want a transaction's fees to be double-counted. + +Implementation Note: Transactions within a package are always validated individually first, and +package validation is used for the transactions that failed. Since package feerate is only +calculated using transactions that are not in the mempool, this implementation detail affects the +outcome of package validation. + +*Rationale*: Packages are intended for incentive-compatible fee-bumping: transaction B is a +"legitimate" fee-bump for transaction A only if B is a descendant of A and has a *higher* feerate +than A. We want to prevent "parents pay for children" behavior; fees of parents should not help +their children, since the parents can be mined without the child. More generally, if transaction A +is not needed in order for transaction B to be mined, A's fees cannot help B. In a +child-with-parents package, simply excluding any parent transactions that meet feerate requirements +individually is sufficient to ensure this. + +*Rationale*: We must not allow a low-feerate child to prevent its parent from being accepted; fees +of children should not negatively impact their parents, since they are not necessary for the parents +to be mined. More generally, if transaction B is not needed in order for transaction A to be mined, +B's fees cannot harm A. In a child-with-parents package, simply validating parents individually +first is sufficient to ensure this. + +*Rationale*: As a principle, we want to avoid accidentally restricting policy in order to be +backward-compatible for users and applications that rely on p2p transaction relay. Concretely, +package validation should not prevent the acceptance of a transaction that would otherwise be +policy-valid on its own. By always accepting a transaction that passes individual validation before +trying package validation, we prevent any unintentional restriction of policy. diff --git a/src/test/fuzz/tx_pool.cpp b/src/test/fuzz/tx_pool.cpp index df5b271d06..f686f4fd86 100644 --- a/src/test/fuzz/tx_pool.cpp +++ b/src/test/fuzz/tx_pool.cpp @@ -234,14 +234,18 @@ FUZZ_TARGET_INIT(tx_pool_standard, initialize_tx_pool) const bool bypass_limits = fuzzed_data_provider.ConsumeBool(); ::fRequireStandard = fuzzed_data_provider.ConsumeBool(); - // Make sure ProcessNewPackage on one transaction works and always fully validates the transaction. + // Make sure ProcessNewPackage on one transaction works. // The result is not guaranteed to be the same as what is returned by ATMP. const auto result_package = WITH_LOCK(::cs_main, return ProcessNewPackage(chainstate, tx_pool, {tx}, true)); - auto it = result_package.m_tx_results.find(tx->GetWitnessHash()); - Assert(it != result_package.m_tx_results.end()); - Assert(it->second.m_result_type == MempoolAcceptResult::ResultType::VALID || - it->second.m_result_type == MempoolAcceptResult::ResultType::INVALID); + // If something went wrong due to a package-specific policy, it might not return a + // validation result for the transaction. + if (result_package.m_state.GetResult() != PackageValidationResult::PCKG_POLICY) { + auto it = result_package.m_tx_results.find(tx->GetWitnessHash()); + Assert(it != result_package.m_tx_results.end()); + Assert(it->second.m_result_type == MempoolAcceptResult::ResultType::VALID || + it->second.m_result_type == MempoolAcceptResult::ResultType::INVALID); + } const auto res = WITH_LOCK(::cs_main, return AcceptToMemoryPool(chainstate, tx, GetTime(), bypass_limits, /*test_accept=*/false)); const bool accepted = res.m_result_type == MempoolAcceptResult::ResultType::VALID; diff --git a/src/test/txpackage_tests.cpp b/src/test/txpackage_tests.cpp index 55919b7f95..e43350344d 100644 --- a/src/test/txpackage_tests.cpp +++ b/src/test/txpackage_tests.cpp @@ -98,7 +98,9 @@ BOOST_FIXTURE_TEST_CASE(package_validation_tests, TestChain100Setup) BOOST_CHECK(it_child != result_parent_child.m_tx_results.end()); BOOST_CHECK_MESSAGE(it_child->second.m_state.IsValid(), "Package validation unexpectedly failed: " << it_child->second.m_state.GetRejectReason()); - + BOOST_CHECK(result_parent_child.m_package_feerate.has_value()); + BOOST_CHECK(result_parent_child.m_package_feerate.value() == + CFeeRate(2 * COIN, GetVirtualTransactionSize(*tx_parent) + GetVirtualTransactionSize(*tx_child))); // A single, giant transaction submitted through ProcessNewPackage fails on single tx policy. CTransactionRef giant_ptx = create_placeholder_tx(999, 999); @@ -110,6 +112,7 @@ BOOST_FIXTURE_TEST_CASE(package_validation_tests, TestChain100Setup) auto it_giant_tx = result_single_large.m_tx_results.find(giant_ptx->GetWitnessHash()); BOOST_CHECK(it_giant_tx != result_single_large.m_tx_results.end()); BOOST_CHECK_EQUAL(it_giant_tx->second.m_state.GetRejectReason(), "tx-size"); + BOOST_CHECK(result_single_large.m_package_feerate == std::nullopt); // Check that mempool size hasn't changed. BOOST_CHECK_EQUAL(m_node.mempool->size(), initialPoolSize); @@ -230,6 +233,7 @@ BOOST_FIXTURE_TEST_CASE(package_submission_tests, TestChain100Setup) BOOST_CHECK_EQUAL(result_unrelated_submit.m_state.GetResult(), PackageValidationResult::PCKG_POLICY); BOOST_CHECK_EQUAL(result_unrelated_submit.m_state.GetRejectReason(), "package-not-child-with-parents"); BOOST_CHECK_EQUAL(m_node.mempool->size(), expected_pool_size); + BOOST_CHECK(result_unrelated_submit.m_package_feerate == std::nullopt); // Parent and Child (and Grandchild) Package Package package_parent_child; @@ -271,6 +275,7 @@ BOOST_FIXTURE_TEST_CASE(package_submission_tests, TestChain100Setup) BOOST_CHECK_EQUAL(result_3gen_submit.m_state.GetResult(), PackageValidationResult::PCKG_POLICY); BOOST_CHECK_EQUAL(result_3gen_submit.m_state.GetRejectReason(), "package-not-child-with-parents"); BOOST_CHECK_EQUAL(m_node.mempool->size(), expected_pool_size); + BOOST_CHECK(result_3gen_submit.m_package_feerate == std::nullopt); } // Child with missing parent. @@ -286,6 +291,7 @@ BOOST_FIXTURE_TEST_CASE(package_submission_tests, TestChain100Setup) BOOST_CHECK_EQUAL(result_missing_parent.m_state.GetRejectReason(), "package-not-child-with-unconfirmed-parents"); BOOST_CHECK_EQUAL(m_node.mempool->size(), expected_pool_size); + BOOST_CHECK(result_missing_parent.m_package_feerate == std::nullopt); } // Submit package with parent + child. @@ -305,6 +311,10 @@ BOOST_FIXTURE_TEST_CASE(package_submission_tests, TestChain100Setup) BOOST_CHECK_EQUAL(m_node.mempool->size(), expected_pool_size); BOOST_CHECK(m_node.mempool->exists(GenTxid::Txid(tx_parent->GetHash()))); BOOST_CHECK(m_node.mempool->exists(GenTxid::Txid(tx_child->GetHash()))); + + // Since both transactions have high feerates, they each passed validation individually. + // Package validation was unnecessary, so there is no package feerate. + BOOST_CHECK(submit_parent_child.m_package_feerate == std::nullopt); } // Already-in-mempool transactions should be detected and de-duplicated. @@ -325,6 +335,8 @@ BOOST_FIXTURE_TEST_CASE(package_submission_tests, TestChain100Setup) BOOST_CHECK_EQUAL(m_node.mempool->size(), expected_pool_size); BOOST_CHECK(m_node.mempool->exists(GenTxid::Txid(tx_parent->GetHash()))); BOOST_CHECK(m_node.mempool->exists(GenTxid::Txid(tx_child->GetHash()))); + + BOOST_CHECK(submit_deduped.m_package_feerate == std::nullopt); } } @@ -399,8 +411,12 @@ BOOST_FIXTURE_TEST_CASE(package_witness_swap_tests, TestChain100Setup) BOOST_CHECK(m_node.mempool->exists(GenTxid::Txid(ptx_parent->GetHash()))); BOOST_CHECK(m_node.mempool->exists(GenTxid::Txid(ptx_child1->GetHash()))); + // Child2 would have been validated individually. + BOOST_CHECK(submit_witness1.m_package_feerate == std::nullopt); + const auto submit_witness2 = ProcessNewPackage(m_node.chainman->ActiveChainstate(), *m_node.mempool, {ptx_parent, ptx_child2}, /*test_accept=*/false); + BOOST_CHECK(submit_witness2.m_package_feerate == std::nullopt); BOOST_CHECK_MESSAGE(submit_witness2.m_state.IsValid(), "Package validation unexpectedly failed: " << submit_witness2.m_state.GetRejectReason()); auto it_parent2_deduped = submit_witness2.m_tx_results.find(ptx_parent->GetWitnessHash()); @@ -424,6 +440,7 @@ BOOST_FIXTURE_TEST_CASE(package_witness_swap_tests, TestChain100Setup) auto it_child_dup = submit_segwit_dedup.m_tx_results.find(ptx_child1->GetWitnessHash()); BOOST_CHECK(it_parent_dup->second.m_result_type == MempoolAcceptResult::ResultType::MEMPOOL_ENTRY); BOOST_CHECK(it_child_dup->second.m_result_type == MempoolAcceptResult::ResultType::MEMPOOL_ENTRY); + BOOST_CHECK(submit_witness2.m_package_feerate == std::nullopt); } // Try submitting Package1{child2, grandchild} where child2 is same-txid-different-witness as @@ -458,6 +475,9 @@ BOOST_FIXTURE_TEST_CASE(package_witness_swap_tests, TestChain100Setup) BOOST_CHECK(m_node.mempool->exists(GenTxid::Txid(ptx_child2->GetHash()))); BOOST_CHECK(!m_node.mempool->exists(GenTxid::Wtxid(ptx_child2->GetWitnessHash()))); BOOST_CHECK(m_node.mempool->exists(GenTxid::Wtxid(ptx_grandchild->GetWitnessHash()))); + + // Since child2 is ignored, grandchild would be validated individually. + BOOST_CHECK(submit_spend_ignored.m_package_feerate == std::nullopt); } // A package Package{parent1, parent2, parent3, child} where the parents are a mixture of @@ -516,11 +536,11 @@ BOOST_FIXTURE_TEST_CASE(package_witness_swap_tests, TestChain100Setup) BOOST_CHECK(parent2_v2_result.m_result_type == MempoolAcceptResult::ResultType::VALID); package_mixed.push_back(ptx_parent2_v1); - // parent3 will be a new transaction + // parent3 will be a new transaction. Put 0 fees on it to make it invalid on its own. auto mtx_parent3 = CreateValidMempoolTransaction(/*input_transaction=*/m_coinbase_txns[3], /*input_vout=*/0, /*input_height=*/0, /*input_signing_key=*/coinbaseKey, /*output_destination=*/acs_spk, - /*output_amount=*/CAmount(49 * COIN), /*submit=*/false); + /*output_amount=*/CAmount(50 * COIN), /*submit=*/false); CTransactionRef ptx_parent3 = MakeTransactionRef(mtx_parent3); package_mixed.push_back(ptx_parent3); @@ -536,7 +556,7 @@ BOOST_FIXTURE_TEST_CASE(package_witness_swap_tests, TestChain100Setup) mtx_mixed_child.vin[0].scriptWitness = acs_witness; mtx_mixed_child.vin[1].scriptWitness = acs_witness; mtx_mixed_child.vin[2].scriptWitness = acs_witness; - mtx_mixed_child.vout.push_back(CTxOut(145 * COIN, mixed_child_spk)); + mtx_mixed_child.vout.push_back(CTxOut((48 + 49 + 50 - 1) * COIN, mixed_child_spk)); CTransactionRef ptx_mixed_child = MakeTransactionRef(mtx_mixed_child); package_mixed.push_back(ptx_mixed_child); @@ -568,6 +588,205 @@ BOOST_FIXTURE_TEST_CASE(package_witness_swap_tests, TestChain100Setup) BOOST_CHECK(!m_node.mempool->exists(GenTxid::Wtxid(ptx_parent2_v1->GetWitnessHash()))); BOOST_CHECK(m_node.mempool->exists(GenTxid::Txid(ptx_parent3->GetHash()))); BOOST_CHECK(m_node.mempool->exists(GenTxid::Txid(ptx_mixed_child->GetHash()))); + + // package feerate should include parent3 and child. It should not include parent1 or parent2_v1. + BOOST_CHECK(mixed_result.m_package_feerate.has_value()); + const CFeeRate expected_feerate(1 * COIN, GetVirtualTransactionSize(*ptx_parent3) + GetVirtualTransactionSize(*ptx_mixed_child)); + BOOST_CHECK_MESSAGE(mixed_result.m_package_feerate.value() == expected_feerate, + strprintf("Expected package feerate %s, got %s", expected_feerate.ToString(), + mixed_result.m_package_feerate.value().ToString())); + } +} + +BOOST_FIXTURE_TEST_CASE(package_cpfp_tests, TestChain100Setup) +{ + mineBlocks(5); + LOCK(::cs_main); + size_t expected_pool_size = m_node.mempool->size(); + CKey child_key; + child_key.MakeNewKey(true); + CScript parent_spk = GetScriptForDestination(WitnessV0KeyHash(child_key.GetPubKey())); + CKey grandchild_key; + grandchild_key.MakeNewKey(true); + CScript child_spk = GetScriptForDestination(WitnessV0KeyHash(grandchild_key.GetPubKey())); + + // zero-fee parent and high-fee child package + const CAmount coinbase_value{50 * COIN}; + const CAmount parent_value{coinbase_value - 0}; + const CAmount child_value{parent_value - COIN}; + + Package package_cpfp; + auto mtx_parent = CreateValidMempoolTransaction(/*input_transaction=*/ m_coinbase_txns[0], /*vout=*/ 0, + /*input_height=*/ 0, /*input_signing_key=*/ coinbaseKey, + /*output_destination=*/ parent_spk, + /*output_amount=*/ parent_value, /*submit=*/ false); + CTransactionRef tx_parent = MakeTransactionRef(mtx_parent); + package_cpfp.push_back(tx_parent); + + auto mtx_child = CreateValidMempoolTransaction(/*input_transaction=*/ tx_parent, /*vout=*/ 0, + /*input_height=*/ 101, /*input_signing_key=*/ child_key, + /*output_destination=*/ child_spk, + /*output_amount=*/ child_value, /*submit=*/ false); + CTransactionRef tx_child = MakeTransactionRef(mtx_child); + package_cpfp.push_back(tx_child); + + // Package feerate is calculated using modified fees, and prioritisetransaction accepts negative + // fee deltas. This should be taken into account. De-prioritise the parent transaction by -1BTC, + // bringing the package feerate to 0. + m_node.mempool->PrioritiseTransaction(tx_parent->GetHash(), -1 * COIN); + { + BOOST_CHECK_EQUAL(m_node.mempool->size(), expected_pool_size); + const auto submit_cpfp_deprio = ProcessNewPackage(m_node.chainman->ActiveChainstate(), *m_node.mempool, + package_cpfp, /*test_accept=*/ false); + BOOST_CHECK_MESSAGE(submit_cpfp_deprio.m_state.IsInvalid(), + "Package validation unexpectedly succeeded: " << submit_cpfp_deprio.m_state.GetRejectReason()); + BOOST_CHECK(submit_cpfp_deprio.m_tx_results.empty()); + BOOST_CHECK_EQUAL(m_node.mempool->size(), expected_pool_size); + const CFeeRate expected_feerate(0, GetVirtualTransactionSize(*tx_parent) + GetVirtualTransactionSize(*tx_child)); + BOOST_CHECK(submit_cpfp_deprio.m_package_feerate.has_value()); + BOOST_CHECK(submit_cpfp_deprio.m_package_feerate.value() == CFeeRate{0}); + BOOST_CHECK_MESSAGE(submit_cpfp_deprio.m_package_feerate.value() == expected_feerate, + strprintf("Expected package feerate %s, got %s", expected_feerate.ToString(), + submit_cpfp_deprio.m_package_feerate.value().ToString())); + } + + // Clear the prioritisation of the parent transaction. + WITH_LOCK(m_node.mempool->cs, m_node.mempool->ClearPrioritisation(tx_parent->GetHash())); + + // Package CPFP: Even though the parent pays 0 absolute fees, the child pays 1 BTC which is + // enough for the package feerate to meet the threshold. + { + BOOST_CHECK_EQUAL(m_node.mempool->size(), expected_pool_size); + const auto submit_cpfp = ProcessNewPackage(m_node.chainman->ActiveChainstate(), *m_node.mempool, + package_cpfp, /*test_accept=*/ false); + expected_pool_size += 2; + BOOST_CHECK_MESSAGE(submit_cpfp.m_state.IsValid(), + "Package validation unexpectedly failed: " << submit_cpfp.m_state.GetRejectReason()); + auto it_parent = submit_cpfp.m_tx_results.find(tx_parent->GetWitnessHash()); + auto it_child = submit_cpfp.m_tx_results.find(tx_child->GetWitnessHash()); + BOOST_CHECK(it_parent != submit_cpfp.m_tx_results.end()); + BOOST_CHECK(it_parent->second.m_result_type == MempoolAcceptResult::ResultType::VALID); + BOOST_CHECK(it_parent->second.m_base_fees.value() == 0); + BOOST_CHECK(it_child != submit_cpfp.m_tx_results.end()); + BOOST_CHECK(it_child->second.m_result_type == MempoolAcceptResult::ResultType::VALID); + BOOST_CHECK(it_child->second.m_base_fees.value() == COIN); + + BOOST_CHECK_EQUAL(m_node.mempool->size(), expected_pool_size); + BOOST_CHECK(m_node.mempool->exists(GenTxid::Txid(tx_parent->GetHash()))); + BOOST_CHECK(m_node.mempool->exists(GenTxid::Txid(tx_child->GetHash()))); + + const CFeeRate expected_feerate(coinbase_value - child_value, + GetVirtualTransactionSize(*tx_parent) + GetVirtualTransactionSize(*tx_child)); + BOOST_CHECK(expected_feerate.GetFeePerK() > 1000); + BOOST_CHECK(submit_cpfp.m_package_feerate.has_value()); + BOOST_CHECK_MESSAGE(submit_cpfp.m_package_feerate.value() == expected_feerate, + strprintf("Expected package feerate %s, got %s", expected_feerate.ToString(), + submit_cpfp.m_package_feerate.value().ToString())); + } + + // Just because we allow low-fee parents doesn't mean we allow low-feerate packages. + // This package just pays 200 satoshis total. This would be enough to pay for the child alone, + // but isn't enough for the entire package to meet the 1sat/vbyte minimum. + Package package_still_too_low; + auto mtx_parent_cheap = CreateValidMempoolTransaction(/*input_transaction=*/ m_coinbase_txns[1], /*vout=*/ 0, + /*input_height=*/ 0, /*input_signing_key=*/ coinbaseKey, + /*output_destination=*/ parent_spk, + /*output_amount=*/ coinbase_value, /*submit=*/ false); + CTransactionRef tx_parent_cheap = MakeTransactionRef(mtx_parent_cheap); + package_still_too_low.push_back(tx_parent_cheap); + + auto mtx_child_cheap = CreateValidMempoolTransaction(/*input_transaction=*/ tx_parent_cheap, /*vout=*/ 0, + /*input_height=*/ 101, /* input_signing_key */ child_key, + /*output_destination=*/ child_spk, + /*output_amount=*/ coinbase_value - 200, /*submit=*/ false); + CTransactionRef tx_child_cheap = MakeTransactionRef(mtx_child_cheap); + package_still_too_low.push_back(tx_child_cheap); + + // Cheap package should fail with package-fee-too-low. + { + BOOST_CHECK_EQUAL(m_node.mempool->size(), expected_pool_size); + const auto submit_package_too_low = ProcessNewPackage(m_node.chainman->ActiveChainstate(), *m_node.mempool, + package_still_too_low, /* test_accept */ false); + BOOST_CHECK_MESSAGE(submit_package_too_low.m_state.IsInvalid(), "Package validation unexpectedly succeeded"); + BOOST_CHECK_EQUAL(submit_package_too_low.m_state.GetResult(), PackageValidationResult::PCKG_POLICY); + BOOST_CHECK_EQUAL(submit_package_too_low.m_state.GetRejectReason(), "package-fee-too-low"); + BOOST_CHECK_EQUAL(m_node.mempool->size(), expected_pool_size); + const CFeeRate child_feerate(200, GetVirtualTransactionSize(*tx_child_cheap)); + BOOST_CHECK(child_feerate.GetFeePerK() > 1000); + const CFeeRate expected_feerate(200, + GetVirtualTransactionSize(*tx_parent_cheap) + GetVirtualTransactionSize(*tx_child_cheap)); + BOOST_CHECK(expected_feerate.GetFeePerK() < 1000); + BOOST_CHECK(submit_package_too_low.m_package_feerate.has_value()); + BOOST_CHECK_MESSAGE(submit_package_too_low.m_package_feerate.value() == expected_feerate, + strprintf("Expected package feerate %s, got %s", expected_feerate.ToString(), + submit_package_too_low.m_package_feerate.value().ToString())); + } + + // Package feerate includes the modified fees of the transactions. + // This means a child with its fee delta from prioritisetransaction can pay for a parent. + m_node.mempool->PrioritiseTransaction(tx_child_cheap->GetHash(), 1 * COIN); + // Now that the child's fees have "increased" by 1 BTC, the cheap package should succeed. + { + const auto submit_prioritised_package = ProcessNewPackage(m_node.chainman->ActiveChainstate(), *m_node.mempool, + package_still_too_low, /*test_accept=*/ false); + expected_pool_size += 2; + BOOST_CHECK_MESSAGE(submit_prioritised_package.m_state.IsValid(), + "Package validation unexpectedly failed" << submit_prioritised_package.m_state.GetRejectReason()); + const CFeeRate expected_feerate(1 * COIN + 200, + GetVirtualTransactionSize(*tx_parent_cheap) + GetVirtualTransactionSize(*tx_child_cheap)); + BOOST_CHECK(submit_prioritised_package.m_package_feerate.has_value()); + BOOST_CHECK_MESSAGE(submit_prioritised_package.m_package_feerate.value() == expected_feerate, + strprintf("Expected package feerate %s, got %s", expected_feerate.ToString(), + submit_prioritised_package.m_package_feerate.value().ToString())); + } + + // Package feerate is calculated without topology in mind; it's just aggregating fees and sizes. + // However, this should not allow parents to pay for children. Each transaction should be + // validated individually first, eliminating sufficient-feerate parents before they are unfairly + // included in the package feerate. It's also important that the low-fee child doesn't prevent + // the parent from being accepted. + Package package_rich_parent; + const CAmount high_parent_fee{1 * COIN}; + auto mtx_parent_rich = CreateValidMempoolTransaction(/*input_transaction=*/ m_coinbase_txns[2], /*vout=*/ 0, + /*input_height=*/ 0, /*input_signing_key=*/ coinbaseKey, + /*output_destination=*/ parent_spk, + /*output_amount=*/ coinbase_value - high_parent_fee, /*submit=*/ false); + CTransactionRef tx_parent_rich = MakeTransactionRef(mtx_parent_rich); + package_rich_parent.push_back(tx_parent_rich); + + auto mtx_child_poor = CreateValidMempoolTransaction(/*input_transaction=*/ tx_parent_rich, /*vout=*/ 0, + /*input_height=*/ 101, /*input_signing_key=*/ child_key, + /*output_destination=*/ child_spk, + /*output_amount=*/ coinbase_value - high_parent_fee, /*submit=*/ false); + CTransactionRef tx_child_poor = MakeTransactionRef(mtx_child_poor); + package_rich_parent.push_back(tx_child_poor); + + // Parent pays 1 BTC and child pays none. The parent should be accepted without the child. + { + BOOST_CHECK_EQUAL(m_node.mempool->size(), expected_pool_size); + const auto submit_rich_parent = ProcessNewPackage(m_node.chainman->ActiveChainstate(), *m_node.mempool, + package_rich_parent, /* test_accept */ false); + expected_pool_size += 1; + BOOST_CHECK_MESSAGE(submit_rich_parent.m_state.IsInvalid(), "Package validation unexpectedly succeeded"); + + // The child would have been validated on its own and failed, then submitted as a "package" of 1. + // The package feerate is just the child's feerate, which is 0sat/vb. + BOOST_CHECK(submit_rich_parent.m_package_feerate.has_value()); + BOOST_CHECK_MESSAGE(submit_rich_parent.m_package_feerate.value() == CFeeRate(), + "expected 0, got " << submit_rich_parent.m_package_feerate.value().ToString()); + BOOST_CHECK_EQUAL(submit_rich_parent.m_state.GetResult(), PackageValidationResult::PCKG_POLICY); + BOOST_CHECK_EQUAL(submit_rich_parent.m_state.GetRejectReason(), "package-fee-too-low"); + + auto it_parent = submit_rich_parent.m_tx_results.find(tx_parent_rich->GetWitnessHash()); + BOOST_CHECK(it_parent != submit_rich_parent.m_tx_results.end()); + BOOST_CHECK(it_parent->second.m_result_type == MempoolAcceptResult::ResultType::VALID); + BOOST_CHECK(it_parent->second.m_state.GetRejectReason() == ""); + BOOST_CHECK_MESSAGE(it_parent->second.m_base_fees.value() == high_parent_fee, + strprintf("rich parent: expected fee %s, got %s", high_parent_fee, it_parent->second.m_base_fees.value())); + + BOOST_CHECK_EQUAL(m_node.mempool->size(), expected_pool_size); + BOOST_CHECK(m_node.mempool->exists(GenTxid::Txid(tx_parent_rich->GetHash()))); + BOOST_CHECK(!m_node.mempool->exists(GenTxid::Txid(tx_child_poor->GetHash()))); } } BOOST_AUTO_TEST_SUITE_END() diff --git a/src/validation.cpp b/src/validation.cpp index c971b020ae..f4b316f67a 100644 --- a/src/validation.cpp +++ b/src/validation.cpp @@ -460,6 +460,10 @@ public: * partially submitted. */ const bool m_package_submission; + /** When true, use package feerates instead of individual transaction feerates for fee-based + * policies such as mempool min fee and min relay fee. + */ + const bool m_package_feerates; /** Parameters for single transaction mempool validation. */ static ATMPArgs SingleAccept(const CChainParams& chainparams, int64_t accept_time, @@ -472,6 +476,7 @@ public: /* m_test_accept */ test_accept, /* m_allow_bip125_replacement */ true, /* m_package_submission */ false, + /* m_package_feerates */ false, }; } @@ -485,6 +490,7 @@ public: /* m_test_accept */ true, /* m_allow_bip125_replacement */ false, /* m_package_submission */ false, // not submitting to mempool + /* m_package_feerates */ false, }; } @@ -498,6 +504,20 @@ public: /* m_test_accept */ false, /* m_allow_bip125_replacement */ false, /* m_package_submission */ true, + /* m_package_feerates */ true, + }; + } + + /** Parameters for a single transaction within a package. */ + static ATMPArgs SingleInPackageAccept(const ATMPArgs& package_args) { + return ATMPArgs{/* m_chainparams */ package_args.m_chainparams, + /* m_accept_time */ package_args.m_accept_time, + /* m_bypass_limits */ false, + /* m_coins_to_uncache */ package_args.m_coins_to_uncache, + /* m_test_accept */ package_args.m_test_accept, + /* m_allow_bip125_replacement */ true, + /* m_package_submission */ false, + /* m_package_feerates */ false, // only 1 transaction }; } @@ -510,14 +530,16 @@ public: std::vector<COutPoint>& coins_to_uncache, bool test_accept, bool allow_bip125_replacement, - bool package_submission) + bool package_submission, + bool package_feerates) : m_chainparams{chainparams}, m_accept_time{accept_time}, m_bypass_limits{bypass_limits}, m_coins_to_uncache{coins_to_uncache}, m_test_accept{test_accept}, m_allow_bip125_replacement{allow_bip125_replacement}, - m_package_submission{package_submission} + m_package_submission{package_submission}, + m_package_feerates{package_feerates} { } }; @@ -819,9 +841,10 @@ bool MemPoolAccept::PreChecks(ATMPArgs& args, Workspace& ws) return state.Invalid(TxValidationResult::TX_NOT_STANDARD, "bad-txns-too-many-sigops", strprintf("%d", nSigOpsCost)); - // No transactions are allowed below minRelayTxFee except from disconnected - // blocks - if (!bypass_limits && !CheckFeeRate(ws.m_vsize, ws.m_modified_fees, state)) return false; + // No individual transactions are allowed below minRelayTxFee and mempool min fee except from + // disconnected blocks and transactions in a package. Package transactions will be checked using + // package feerate later. + if (!bypass_limits && !args.m_package_feerates && !CheckFeeRate(ws.m_vsize, ws.m_modified_fees, state)) return false; ws.m_iters_conflicting = m_pool.GetIterSet(ws.m_conflicts); // Calculate in-mempool ancestors, up to a limit. @@ -1205,12 +1228,27 @@ PackageMempoolAcceptResult MemPoolAccept::AcceptMultipleTransactions(const std:: m_viewmempool.PackageAddTransaction(ws.m_ptx); } + // Transactions must meet two minimum feerates: the mempool minimum fee and min relay fee. + // For transactions consisting of exactly one child and its parents, it suffices to use the + // package feerate (total modified fees / total virtual size) to check this requirement. + const auto m_total_vsize = std::accumulate(workspaces.cbegin(), workspaces.cend(), int64_t{0}, + [](int64_t sum, auto& ws) { return sum + ws.m_vsize; }); + const auto m_total_modified_fees = std::accumulate(workspaces.cbegin(), workspaces.cend(), CAmount{0}, + [](CAmount sum, auto& ws) { return sum + ws.m_modified_fees; }); + const CFeeRate package_feerate(m_total_modified_fees, m_total_vsize); + TxValidationState placeholder_state; + if (args.m_package_feerates && + !CheckFeeRate(m_total_vsize, m_total_modified_fees, placeholder_state)) { + package_state.Invalid(PackageValidationResult::PCKG_POLICY, "package-fee-too-low"); + return PackageMempoolAcceptResult(package_state, package_feerate, {}); + } + // Apply package mempool ancestor/descendant limits. Skip if there is only one transaction, // because it's unnecessary. Also, CPFP carve out can increase the limit for individual // transactions, but this exemption is not extended to packages in CheckPackageLimits(). std::string err_string; if (txns.size() > 1 && !PackageMempoolChecks(txns, package_state)) { - return PackageMempoolAcceptResult(package_state, std::move(results)); + return PackageMempoolAcceptResult(package_state, package_feerate, std::move(results)); } for (Workspace& ws : workspaces) { @@ -1218,7 +1256,7 @@ PackageMempoolAcceptResult MemPoolAccept::AcceptMultipleTransactions(const std:: // Exit early to avoid doing pointless work. Update the failed tx result; the rest are unfinished. package_state.Invalid(PackageValidationResult::PCKG_TX, "transaction failed"); results.emplace(ws.m_ptx->GetWitnessHash(), MempoolAcceptResult::Failure(ws.m_state)); - return PackageMempoolAcceptResult(package_state, std::move(results)); + return PackageMempoolAcceptResult(package_state, package_feerate, std::move(results)); } if (args.m_test_accept) { // When test_accept=true, transactions that pass PolicyScriptChecks are valid because there are @@ -1229,14 +1267,14 @@ PackageMempoolAcceptResult MemPoolAccept::AcceptMultipleTransactions(const std:: } } - if (args.m_test_accept) return PackageMempoolAcceptResult(package_state, std::move(results)); + if (args.m_test_accept) return PackageMempoolAcceptResult(package_state, package_feerate, std::move(results)); if (!SubmitPackage(args, workspaces, package_state, results)) { // PackageValidationState filled in by SubmitPackage(). - return PackageMempoolAcceptResult(package_state, std::move(results)); + return PackageMempoolAcceptResult(package_state, package_feerate, std::move(results)); } - return PackageMempoolAcceptResult(package_state, std::move(results)); + return PackageMempoolAcceptResult(package_state, package_feerate, std::move(results)); } PackageMempoolAcceptResult MemPoolAccept::AcceptPackage(const Package& package, ATMPArgs& args) @@ -1303,6 +1341,8 @@ PackageMempoolAcceptResult MemPoolAccept::AcceptPackage(const Package& package, // transactions that are already in the mempool, and only call AcceptMultipleTransactions() with // the new transactions. This ensures we don't double-count transaction counts and sizes when // checking ancestor/descendant limits, or double-count transaction fees for fee-related policy. + ATMPArgs single_args = ATMPArgs::SingleInPackageAccept(args); + bool quit_early{false}; std::vector<CTransactionRef> txns_new; for (const auto& tx : package) { const auto& wtxid = tx->GetWitnessHash(); @@ -1329,18 +1369,43 @@ PackageMempoolAcceptResult MemPoolAccept::AcceptPackage(const Package& package, results.emplace(wtxid, MempoolAcceptResult::MempoolTxDifferentWitness(iter.value()->GetTx().GetWitnessHash())); } else { // Transaction does not already exist in the mempool. - txns_new.push_back(tx); + // Try submitting the transaction on its own. + const auto single_res = AcceptSingleTransaction(tx, single_args); + if (single_res.m_result_type == MempoolAcceptResult::ResultType::VALID) { + // The transaction succeeded on its own and is now in the mempool. Don't include it + // in package validation, because its fees should only be "used" once. + assert(m_pool.exists(GenTxid::Wtxid(wtxid))); + results.emplace(wtxid, single_res); + } else if (single_res.m_state.GetResult() != TxValidationResult::TX_MEMPOOL_POLICY && + single_res.m_state.GetResult() != TxValidationResult::TX_MISSING_INPUTS) { + // Package validation policy only differs from individual policy in its evaluation + // of feerate. For example, if a transaction fails here due to violation of a + // consensus rule, the result will not change when it is submitted as part of a + // package. To minimize the amount of repeated work, unless the transaction fails + // due to feerate or missing inputs (its parent is a previous transaction in the + // package that failed due to feerate), don't run package validation. Note that this + // decision might not make sense if different types of packages are allowed in the + // future. Continue individually validating the rest of the transactions, because + // some of them may still be valid. + quit_early = true; + } else { + txns_new.push_back(tx); + } } } // Nothing to do if the entire package has already been submitted. - if (txns_new.empty()) return PackageMempoolAcceptResult(package_state, std::move(results)); + if (quit_early || txns_new.empty()) { + // No package feerate when no package validation was done. + return PackageMempoolAcceptResult(package_state, std::move(results)); + } // Validate the (deduplicated) transactions as a package. auto submission_result = AcceptMultipleTransactions(txns_new, args); // Include already-in-mempool transaction results in the final result. for (const auto& [wtxid, mempoolaccept_res] : results) { submission_result.m_tx_results.emplace(wtxid, mempoolaccept_res); } + if (submission_result.m_state.IsValid()) assert(submission_result.m_package_feerate.has_value()); return submission_result; } diff --git a/src/validation.h b/src/validation.h index b13e7f3d8b..53ea2d4aea 100644 --- a/src/validation.h +++ b/src/validation.h @@ -234,11 +234,19 @@ struct PackageMempoolAcceptResult * was a package-wide error (see result in m_state), m_tx_results will be empty. */ std::map<const uint256, const MempoolAcceptResult> m_tx_results; + /** Package feerate, defined as the aggregated modified fees divided by the total virtual size + * of all transactions in the package. May be unavailable if some inputs were not available or + * a transaction failure caused validation to terminate early. */ + std::optional<CFeeRate> m_package_feerate; explicit PackageMempoolAcceptResult(PackageValidationState state, std::map<const uint256, const MempoolAcceptResult>&& results) : m_state{state}, m_tx_results(std::move(results)) {} + explicit PackageMempoolAcceptResult(PackageValidationState state, CFeeRate feerate, + std::map<const uint256, const MempoolAcceptResult>&& results) + : m_state{state}, m_tx_results(std::move(results)), m_package_feerate{feerate} {} + /** Constructor to create a PackageMempoolAcceptResult from a single MempoolAcceptResult */ explicit PackageMempoolAcceptResult(const uint256& wtxid, const MempoolAcceptResult& result) : m_tx_results{ {wtxid, result} } {} |