Method ProcessGetData

src/net_processing.cpp:2548–2617

}

void PeerManagerImpl::ProcessGetData(CNode& pfrom, Peer& peer, const std::atomic<bool>& interruptMsgProc)
{
    AssertLockNotHeld(cs_main);

    auto tx_relay = peer.GetTxRelay();

    std::deque<CInv>::iterator it = peer.m_getdata_requests.begin();
    std::vector<CInv> vNotFound;

    // Process as many TX items from the front of the getdata queue as
    // possible, since they're common and it's efficient to batch process
    // them.
    while (it != peer.m_getdata_requests.end() && it->IsGenTxMsg()) {
        if (interruptMsgProc) return;
        // The send buffer provides backpressure. If there's no space in
        // the buffer, pause processing until the next call.
        if (pfrom.fPauseSend) break;

        const CInv &inv = *it++;

        if (tx_relay == nullptr) {
            // Ignore GETDATA requests for transactions from block-relay-only
            // peers and peers that asked us not to announce transactions.
            continue;
        }

        if (auto tx{FindTxForGetData(*tx_relay, ToGenTxid(inv))}) {
            // WTX and WITNESS_TX imply we serialize with witness
            const auto maybe_with_witness = (inv.IsMsgTx() ? TX_NO_WITNESS : TX_WITH_WITNESS);
            MakeAndPushMessage(pfrom, NetMsgType::TX, maybe_with_witness(*tx));
            m_mempool.RemoveUnbroadcastTx(tx->GetHash());
        } else {
            vNotFound.push_back(inv);
        }
    }

    // Only process one BLOCK item per call, since they're uncommon and can be
    // expensive to process.
    if (it != peer.m_getdata_requests.end() && !pfrom.fPauseSend) {
        const CInv &inv = *it++;
        if (inv.IsGenBlkMsg()) {
            ProcessGetBlockData(pfrom, peer, inv);
        }
        // else: If the first item on the queue is an unknown type, we erase it
        // and continue processing the queue on the next call.
        // NOTE: previously we wouldn't do so and the peer sending us a malformed GETDATA could
        // result in never making progress and this thread using 100% allocated CPU. See
        // https://bitcoincore.org/en/2024/07/03/disclose-getdata-cpu.
    }

    peer.m_getdata_requests.erase(peer.m_getdata_requests.begin(), it);

    if (!vNotFound.empty()) {
        // Let the peer know that we didn't find what it asked for, so it doesn't
        // have to wait around forever.
        // SPV clients care about this message: it's needed when they are
        // recursively walking the dependencies of relevant unconfirmed
        // transactions. SPV clients want to do that because they want to know