Inside Bitcoin

501}
502
503void TxDownloadManagerImpl::MempoolRejectedPackage(const Package& package)
504{
505    RecentRejectsReconsiderableFilter().insert(GetPackageHash(package));
506}
507
508std::pair<bool, std::optional<PackageToValidate>> TxDownloadManagerImpl::ReceivedTx(NodeId nodeid, const CTransactionRef& ptx)
509{
510    const Txid& txid = ptx->GetHash();
511    const Wtxid& wtxid = ptx->GetWitnessHash();
512
513    // Mark that we have received a response
514    m_txrequest.ReceivedResponse(nodeid, txid.ToUint256());
515    if (ptx->HasWitness()) m_txrequest.ReceivedResponse(nodeid, wtxid.ToUint256());
516
517    // First check if we should drop this tx.
518    // We do the AlreadyHaveTx() check using wtxid, rather than txid - in the
519    // absence of witness malleation, this is strictly better, because the
520    // recent rejects filter may contain the wtxid but rarely contains
521    // the txid of a segwit transaction that has been rejected.
522    // In the presence of witness malleation, it's possible that by only
523    // doing the check with wtxid, we could overlook a transaction which
524    // was confirmed with a different witness, or exists in our mempool
525    // with a different witness, but this has limited downside:
526    // mempool validation does its own lookup of whether we have the txid
527    // already; and an adversary can already relay us old transactions
528    // (older than our recency filter) if trying to DoS us, without any need
529    // for witness malleation.
530    if (AlreadyHaveTx(wtxid, /*include_reconsiderable=*/false)) {
531        // If a tx is detected by m_lazy_recent_rejects it is ignored. Because we haven't
532        // submitted the tx to our mempool, we won't have computed a DoS
533        // score for it or determined exactly why we consider it invalid.
534        //
535        // This means we won't penalize any peer subsequently relaying a DoSy
536        // tx (even if we penalized the first peer who gave it to us) because
537        // we have to account for m_lazy_recent_rejects showing false positives. In
538        // other words, we shouldn't penalize a peer if we aren't *sure* they
539        // submitted a DoSy tx.
540        //
541        // Note that m_lazy_recent_rejects doesn't just record DoSy or invalid
542        // transactions, but any tx not accepted by the mempool, which may be
543        // due to node policy (vs. consensus). So we can't blanket penalize a
544        // peer simply for relaying a tx that our m_lazy_recent_rejects has caught,
545        // regardless of false positives.
546        return {false, std::nullopt};
547    } else if (RecentRejectsReconsiderableFilter().contains(wtxid.ToUint256())) {
548        // When a transaction is already in m_lazy_recent_rejects_reconsiderable, we shouldn't submit
549        // it by itself again. However, look for a matching child in the orphanage, as it is
550        // possible that they succeed as a package.
551        LogDebug(BCLog::TXPACKAGES, "found tx %s (wtxid=%s) in reconsiderable rejects, looking for child in orphanage\n",
552                 txid.ToString(), wtxid.ToString());
553        return {false, Find1P1CPackage(ptx, nodeid)};
554    }
555
556
557    return {true, std::nullopt};
558}
559
560bool TxDownloadManagerImpl::HaveMoreWork(NodeId nodeid)
561{
562    return m_orphanage->HaveTxToReconsider(nodeid);
563}
564
565CTransactionRef TxDownloadManagerImpl::GetTxToReconsider(NodeId nodeid)
566{
567    return m_orphanage->GetTxToReconsider(nodeid);
568}
569
570void TxDownloadManagerImpl::CheckIsEmpty(NodeId nodeid)
571{
572    assert(m_txrequest.Count(nodeid) == 0);
573    assert(m_orphanage->UsageByPeer(nodeid) == 0);
574}
575void TxDownloadManagerImpl::CheckIsEmpty()
576{
577    assert(m_orphanage->TotalOrphanUsage() == 0);
578    assert(m_orphanage->CountUniqueOrphans() == 0);
579    assert(m_txrequest.Size() == 0);
580    assert(m_num_wtxid_peers == 0);
581}
582std::vector<TxOrphanage::OrphanInfo> TxDownloadManagerImpl::GetOrphanTransactions() const
583{
584    return m_orphanage->GetOrphanTransactions();
585}
586} // namespace node
587