Method ProcessOrphanTx

src/net_processing.cpp:3256–3291

NOTE: the orphan processing used to be uninterruptible and quadratic, which could allow a peer to stall the node for hours with specially crafted transactions. See https://bitcoincore.org/en/2024/07/03/disclose-orphan-dos.

// NOTE: the orphan processing used to be uninterruptible and quadratic, which could allow a peer to stall the node for
// hours with specially crafted transactions. See https://bitcoincore.org/en/2024/07/03/disclose-orphan-dos.
bool PeerManagerImpl::ProcessOrphanTx(Peer& peer)
{
    AssertLockHeld(g_msgproc_mutex);
    LOCK2(::cs_main, m_tx_download_mutex);

    CTransactionRef porphanTx = nullptr;

    while (CTransactionRef porphanTx = m_txdownloadman.GetTxToReconsider(peer.m_id)) {
        const MempoolAcceptResult result = m_chainman.ProcessTransaction(porphanTx);
        const TxValidationState& state = result.m_state;
        const Txid& orphanHash = porphanTx->GetHash();
        const Wtxid& orphan_wtxid = porphanTx->GetWitnessHash();

        if (result.m_result_type == MempoolAcceptResult::ResultType::VALID) {
            LogDebug(BCLog::TXPACKAGES, "   accepted orphan tx %s (wtxid=%s)\n", orphanHash.ToString(), orphan_wtxid.ToString());
            ProcessValidTx(peer.m_id, porphanTx, result.m_replaced_transactions);
            return true;
        } else if (state.GetResult() != TxValidationResult::TX_MISSING_INPUTS) {
            LogDebug(BCLog::TXPACKAGES, "   invalid orphan tx %s (wtxid=%s) from peer=%d. %s\n",
                orphanHash.ToString(),
                orphan_wtxid.ToString(),
                peer.m_id,
                state.ToString());

            if (Assume(state.IsInvalid() &&
                       state.GetResult() != TxValidationResult::TX_UNKNOWN &&
                       state.GetResult() != TxValidationResult::TX_NO_MEMPOOL &&
                       state.GetResult() != TxValidationResult::TX_RESULT_UNSET)) {
                ProcessInvalidTx(peer.m_id, porphanTx, state, /*first_time_failure=*/false);
            }
            return true;
        }
    }

    return false;
}

bool PeerManagerImpl::PrepareBlockFilterRequest(CNode& node, Peer& peer,
                                                BlockFilterType filter_type, uint32_t start_height,