bitcoin/src/test/util/txmempool.cpp

// Copyright (c) 2022-present 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 <test/util/txmempool.h>

#include <chainparams.h>
#include <node/context.h>
#include <node/mempool_args.h>
#include <policy/rbf.h>
#include <policy/truc_policy.h>
#include <txmempool.h>
#include <test/util/transaction_utils.h>
#include <util/check.h>
#include <util/time.h>
#include <util/translation.h>
#include <validation.h>

using node::NodeContext;

CTxMemPool::Options MemPoolOptionsForTest(const NodeContext& node)
{
    CTxMemPool::Options mempool_opts{
        // Default to always checking mempool regardless of
        // chainparams.DefaultConsistencyChecks for tests
        .check_ratio = 1,
        .signals = node.validation_signals.get(),
    };
    const auto result{ApplyArgsManOptions(*node.args, ::Params(), mempool_opts)};
    Assert(result);
    return mempool_opts;
}

CTxMemPoolEntry TestMemPoolEntryHelper::FromTx(const CMutableTransaction& tx) const
{
    return FromTx(MakeTransactionRef(tx));
}

CTxMemPoolEntry TestMemPoolEntryHelper::FromTx(const CTransactionRef& tx) const
{
    return CTxMemPoolEntry{TxGraph::Ref(), tx, nFee, TicksSinceEpoch<std::chrono::seconds>(time), nHeight, m_sequence, spendsCoinbase, sigOpCost, lp};
}

std::optional<std::string> CheckPackageMempoolAcceptResult(const Package& txns,
                                                           const PackageMempoolAcceptResult& result,
                                                           bool expect_valid,
                                                           const CTxMemPool* mempool)
{
    if (expect_valid) {
        if (result.m_state.IsInvalid()) {
            return strprintf("Package validation unexpectedly failed: %s", result.m_state.ToString());
        }
    } else {
        if (result.m_state.IsValid()) {
            return strprintf("Package validation unexpectedly succeeded. %s", result.m_state.ToString());
        }
    }
    if (result.m_state.GetResult() != PackageValidationResult::PCKG_POLICY && txns.size() != result.m_tx_results.size()) {
        return strprintf("txns size %u does not match tx results size %u", txns.size(), result.m_tx_results.size());
    }
    for (const auto& tx : txns) {
        const auto& wtxid = tx->GetWitnessHash();
        if (!result.m_tx_results.contains(wtxid)) {
            return strprintf("result not found for tx %s", wtxid.ToString());
        }

        const auto& atmp_result = result.m_tx_results.at(wtxid);
        const bool valid{atmp_result.m_result_type == MempoolAcceptResult::ResultType::VALID};
        if (expect_valid && atmp_result.m_state.IsInvalid()) {
            return strprintf("tx %s unexpectedly failed: %s", wtxid.ToString(), atmp_result.m_state.ToString());
        }

        // Each subpackage is allowed MAX_REPLACEMENT_CANDIDATES replacements (only checking individually here)
        if (atmp_result.m_replaced_transactions.size() > MAX_REPLACEMENT_CANDIDATES) {
            return strprintf("tx %s result replaced too many transactions",
                                wtxid.ToString());
        }

        // Replacements can't happen for subpackages larger than 2
        if (!atmp_result.m_replaced_transactions.empty() &&
            atmp_result.m_wtxids_fee_calculations.has_value() && atmp_result.m_wtxids_fee_calculations.value().size() > 2) {
             return strprintf("tx %s was part of a too-large package RBF subpackage",
                                wtxid.ToString());
        }

        if (!atmp_result.m_replaced_transactions.empty() && mempool) {
            LOCK(mempool->cs);
            // If replacements occurred and it used 2 transactions, this is a package RBF and should result in a cluster of size 2
            if (atmp_result.m_wtxids_fee_calculations.has_value() && atmp_result.m_wtxids_fee_calculations.value().size() == 2) {
                const auto cluster = mempool->GatherClusters({tx->GetHash()});
                if (cluster.size() != 2) return strprintf("tx %s has too many ancestors or descendants for a package rbf", wtxid.ToString());
            }
        }

        // m_vsize and m_base_fees should exist iff the result was VALID or MEMPOOL_ENTRY
        const bool mempool_entry{atmp_result.m_result_type == MempoolAcceptResult::ResultType::MEMPOOL_ENTRY};
        if (atmp_result.m_base_fees.has_value() != (valid || mempool_entry)) {
            return strprintf("tx %s result should %shave m_base_fees", wtxid.ToString(), valid || mempool_entry ? "" : "not ");
        }
        if (atmp_result.m_vsize.has_value() != (valid || mempool_entry)) {
            return strprintf("tx %s result should %shave m_vsize", wtxid.ToString(), valid || mempool_entry ? "" : "not ");
        }

        // m_other_wtxid should exist iff the result was DIFFERENT_WITNESS
        const bool diff_witness{atmp_result.m_result_type == MempoolAcceptResult::ResultType::DIFFERENT_WITNESS};
        if (atmp_result.m_other_wtxid.has_value() != diff_witness) {
            return strprintf("tx %s result should %shave m_other_wtxid", wtxid.ToString(), diff_witness ? "" : "not ");
        }

        // m_effective_feerate and m_wtxids_fee_calculations should exist iff the result was valid
        // or if the failure was TX_RECONSIDERABLE
        const bool valid_or_reconsiderable{atmp_result.m_result_type == MempoolAcceptResult::ResultType::VALID ||
                    atmp_result.m_state.GetResult() == TxValidationResult::TX_RECONSIDERABLE};
        if (atmp_result.m_effective_feerate.has_value() != valid_or_reconsiderable) {
            return strprintf("tx %s result should %shave m_effective_feerate",
                                    wtxid.ToString(), valid ? "" : "not ");
        }
        if (atmp_result.m_wtxids_fee_calculations.has_value() != valid_or_reconsiderable) {
            return strprintf("tx %s result should %shave m_effective_feerate",
                                    wtxid.ToString(), valid ? "" : "not ");
        }

        if (mempool) {
            // The tx by txid should be in the mempool iff the result was not INVALID.
            const bool txid_in_mempool{atmp_result.m_result_type != MempoolAcceptResult::ResultType::INVALID};
            if (mempool->exists(tx->GetHash()) != txid_in_mempool) {
                return strprintf("tx %s should %sbe in mempool", wtxid.ToString(), txid_in_mempool ? "" : "not ");
            }
            // Additionally, if the result was DIFFERENT_WITNESS, we shouldn't be able to find the tx in mempool by wtxid.
            if (tx->HasWitness() && atmp_result.m_result_type == MempoolAcceptResult::ResultType::DIFFERENT_WITNESS) {
                if (mempool->exists(wtxid)) {
                    return strprintf("wtxid %s should not be in mempool", wtxid.ToString());
                }
            }
            for (const auto& tx_ref : atmp_result.m_replaced_transactions) {
                if (mempool->exists(tx_ref->GetHash())) {
                    return strprintf("tx %s should not be in mempool as it was replaced", tx_ref->GetWitnessHash().ToString());
                }
            }
        }
    }
    return std::nullopt;
}

void CheckMempoolEphemeralInvariants(const CTxMemPool& tx_pool)
{
    LOCK(tx_pool.cs);
    for (const auto& tx_info : tx_pool.infoAll()) {
        const auto& entry = *Assert(tx_pool.GetEntry(tx_info.tx->GetHash()));

        std::vector<uint32_t> dust_indexes = GetDust(*tx_info.tx, tx_pool.m_opts.dust_relay_feerate);

        Assert(dust_indexes.size() < 2);

        if (dust_indexes.empty()) continue;

        // Transaction must have no base fee
        Assert(entry.GetFee() == 0 && entry.GetModifiedFee() == 0);

        // Transaction has single dust; make sure it's swept or will not be mined
        const auto& children = tx_pool.GetChildren(entry);

        // Multiple children should never happen as non-dust-spending child
        // can get mined as package
        Assert(children.size() < 2);

        if (children.empty()) {
            // No children and no fees; modified fees aside won't get mined so it's fine
            // Happens naturally if child spend is RBF cycled away.
            continue;
        }

        // Only-child should be spending the dust
        const auto& only_child = children.begin()->get().GetTx();
        COutPoint dust_outpoint{tx_info.tx->GetHash(), dust_indexes[0]};
        Assert(std::any_of(only_child.vin.begin(), only_child.vin.end(), [&dust_outpoint](const CTxIn& txin) {
            return txin.prevout == dust_outpoint;
            }));
    }
}

void CheckMempoolTRUCInvariants(const CTxMemPool& tx_pool)
{
    LOCK(tx_pool.cs);
    for (const auto& tx_info : tx_pool.infoAll()) {
        const auto& entry = *Assert(tx_pool.GetEntry(tx_info.tx->GetHash()));
        auto [desc_count, desc_size, desc_fees] = tx_pool.CalculateDescendantData(entry);
        auto [anc_count, anc_size, anc_fees] = tx_pool.CalculateAncestorData(entry);

        if (tx_info.tx->version == TRUC_VERSION) {
            // Check that special maximum virtual size is respected
            Assert(entry.GetTxSize() <= TRUC_MAX_VSIZE);

            // Check that special TRUC ancestor/descendant limits and rules are always respected
            Assert(desc_count <= TRUC_DESCENDANT_LIMIT);
            Assert(anc_count <= TRUC_ANCESTOR_LIMIT);
            Assert(desc_size <= TRUC_MAX_VSIZE + TRUC_CHILD_MAX_VSIZE);
            Assert(anc_size <= TRUC_MAX_VSIZE + TRUC_CHILD_MAX_VSIZE);
            // If this transaction has at least 1 ancestor, it's a "child" and has restricted weight.
            if (anc_count > 1) {
                Assert(entry.GetTxSize() <= TRUC_CHILD_MAX_VSIZE);
                // All TRUC transactions must only have TRUC unconfirmed parents.
                const auto& parents = tx_pool.GetParents(entry);
                Assert(parents.begin()->get().GetSharedTx()->version == TRUC_VERSION);
            }
        } else if (anc_count > 1) {
            // All non-TRUC transactions must only have non-TRUC unconfirmed parents.
            for (const auto& parent : tx_pool.GetParents(entry)) {
                Assert(parent.get().GetSharedTx()->version != TRUC_VERSION);
            }
        }
    }
}

void TryAddToMempool(CTxMemPool& tx_pool, const CTxMemPoolEntry& entry)
{
    LOCK2(cs_main, tx_pool.cs);
    auto changeset = tx_pool.GetChangeSet();
    changeset->StageAddition(entry.GetSharedTx(), entry.GetFee(),
            entry.GetTime().count(), entry.GetHeight(), entry.GetSequence(),
            entry.GetSpendsCoinbase(), entry.GetSigOpCost(), entry.GetLockPoints());
    if (changeset->CheckMemPoolPolicyLimits()) changeset->Apply();
}

void MockMempoolMinFee(const CFeeRate& target_feerate, CTxMemPool& mempool)
{
    LOCK2(cs_main, mempool.cs);
    // Transactions in the mempool will affect the new minimum feerate.
    assert(mempool.size() == 0);
    // The target feerate cannot be too low...
    // ...otherwise the transaction's feerate will need to be negative.
    assert(target_feerate > mempool.m_opts.incremental_relay_feerate);
    // ...otherwise this is not meaningful. The feerate policy uses the maximum of both feerates.
    assert(target_feerate > mempool.m_opts.min_relay_feerate);

    // Manually create an invalid transaction. Manually set the fee in the CTxMemPoolEntry to
    // achieve the exact target feerate.
    CMutableTransaction mtx{};
    mtx.vin.emplace_back(COutPoint{Txid::FromUint256(uint256{123}), 0});
    mtx.vout.emplace_back(1 * COIN, GetScriptForDestination(WitnessV0ScriptHash(CScript() << OP_TRUE)));
    // Set a large size so that the fee evaluated at target_feerate (which is usually in sats/kvB) is an integer.
    // Otherwise, GetMinFee() may end up slightly different from target_feerate.
    BulkTransaction(mtx, 4000);
    const auto tx{MakeTransactionRef(mtx)};
    LockPoints lp;
    // The new mempool min feerate is equal to the removed package's feerate + incremental feerate.
    const auto tx_fee = target_feerate.GetFee(GetVirtualTransactionSize(*tx)) -
        mempool.m_opts.incremental_relay_feerate.GetFee(GetVirtualTransactionSize(*tx));
    {
        auto changeset = mempool.GetChangeSet();
        changeset->StageAddition(tx, /*fee=*/tx_fee,
                /*time=*/0, /*entry_height=*/1, /*entry_sequence=*/0,
                /*spends_coinbase=*/true, /*sigops_cost=*/1, lp);
        changeset->Apply();
    }
    mempool.TrimToSize(0);
    assert(mempool.GetMinFee() == target_feerate);
}