net_processing.cpp

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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2016 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 <net_processing.h>

#include <addrman.h>
#include <arith_uint256.h>
#include <blockencodings.h>
#include <chainparams.h>
#include <consensus/validation.h>
#include <hash.h>
#include <init.h>
#include <validation.h>
#include <merkleblock.h>
#include <netmessagemaker.h>
#include <netbase.h>
#include <policy/fees.h>
#include <policy/policy.h>
#include <primitives/block.h>
#include <primitives/transaction.h>
#include <random.h>
#include <reverse_iterator.h>
#include <scheduler.h>
#include <tinyformat.h>
#include <txdb.h>
#include <txmempool.h>
#include <ui_interface.h>
#include <util.h>
#include <utilmoneystr.h>
#include <utilstrencodings.h>

#include <memory>

#include <spork.h>
#include <governance/governance.h>
#include <masternode/masternode-payments.h>
#include <masternode/masternode-sync.h>
#include <masternode/masternode-meta.h>
#ifdef ENABLE_WALLET
#include <privatesend/privatesend-client.h>
#endif // ENABLE_WALLET
#include <privatesend/privatesend-server.h>

#include <evo/deterministicmns.h>
#include <evo/mnauth.h>
#include <evo/simplifiedmns.h>
#include <llmq/quorums_blockprocessor.h>
#include <llmq/quorums_commitment.h>
#include <llmq/quorums_chainlocks.h>
#include <llmq/quorums_dkgsessionmgr.h>
#include <llmq/quorums_init.h>
#include <llmq/quorums_instantsend.h>
#include <llmq/quorums_signing.h>
#include <llmq/quorums_signing_shares.h>

#if defined(NDEBUG)
# error "Dash Core cannot be compiled without assertions."
#endif

static constexpr int32_t MAX_PEER_OBJECT_IN_FLIGHT = 100;
static constexpr int32_t MAX_PEER_OBJECT_ANNOUNCEMENTS = 2 * MAX_INV_SZ;
static constexpr std::chrono::microseconds INBOUND_PEER_TX_DELAY{std::chrono::seconds{2}};
static constexpr std::chrono::microseconds GETDATA_TX_INTERVAL{std::chrono::seconds{60}};
static constexpr std::chrono::microseconds MAX_GETDATA_RANDOM_DELAY{std::chrono::seconds{2}};
static constexpr int64_t TX_EXPIRY_INTERVAL_FACTOR = 10;
static_assert(INBOUND_PEER_TX_DELAY >= MAX_GETDATA_RANDOM_DELAY,
"To preserve security, MAX_GETDATA_RANDOM_DELAY should not exceed INBOUND_PEER_DELAY");
static const unsigned int MAX_GETDATA_SZ = 1000;

std::atomic<int64_t> nTimeBestReceived(0); // Used only to inform the wallet of when we last received a block
bool g_enable_bip61 = DEFAULT_ENABLE_BIP61;

struct IteratorComparator
{
    template<typename I>
    bool operator()(const I& a, const I& b) const
    {
        return &(*a) < &(*b);
    }
};

struct COrphanTx {
    // When modifying, adapt the copy of this definition in tests/DoS_tests.
    CTransactionRef tx;
    NodeId fromPeer;
    int64_t nTimeExpire;
    size_t nTxSize;
};
static CCriticalSection g_cs_orphans;
std::map<uint256, COrphanTx> mapOrphanTransactions GUARDED_BY(g_cs_orphans);
std::map<COutPoint, std::set<std::map<uint256, COrphanTx>::iterator, IteratorComparator>> mapOrphanTransactionsByPrev GUARDED_BY(g_cs_orphans);
size_t nMapOrphanTransactionsSize = 0;
void EraseOrphansFor(NodeId peer);

static size_t vExtraTxnForCompactIt GUARDED_BY(g_cs_orphans) = 0;
static std::vector<std::pair<uint256, CTransactionRef>> vExtraTxnForCompact GUARDED_BY(g_cs_orphans);

static const uint64_t RANDOMIZER_ID_ADDRESS_RELAY = 0x3cac0035b5866b90ULL; // SHA256("main address relay")[0:8]

static const int STALE_RELAY_AGE_LIMIT = 30 * 24 * 60 * 60;

static const int HISTORICAL_BLOCK_AGE = 7 * 24 * 60 * 60;

static constexpr unsigned int AVG_LOCAL_ADDRESS_BROADCAST_INTERVAL = 24 * 60 * 60;
static const unsigned int AVG_ADDRESS_BROADCAST_INTERVAL = 30;
static const unsigned int INVENTORY_BROADCAST_INTERVAL = 5;
static constexpr unsigned int INVENTORY_BROADCAST_MAX_PER_1MB_BLOCK = 4 * 7 * INVENTORY_BROADCAST_INTERVAL;

// Internal stuff
namespace {
    int nSyncStarted = 0;

    std::map<uint256, std::pair<NodeId, bool>> mapBlockSource;

    std::unique_ptr<CRollingBloomFilter> recentRejects;
    uint256 hashRecentRejectsChainTip;

    struct QueuedBlock {
        uint256 hash;
        const CBlockIndex* pindex;                               
        bool fValidatedHeaders;                                  
        std::unique_ptr<PartiallyDownloadedBlock> partialBlock;  
    };
    std::map<uint256, std::pair<NodeId, std::list<QueuedBlock>::iterator> > mapBlocksInFlight;

    std::list<NodeId> lNodesAnnouncingHeaderAndIDs;

    int nPreferredDownload = 0;

    int nPeersWithValidatedDownloads = 0;

    int g_outbound_peers_with_protect_from_disconnect = 0;

    std::atomic<int64_t> g_last_tip_update(0);

    typedef std::map<uint256, CTransactionRef> MapRelay;
    MapRelay mapRelay;
    std::deque<std::pair<int64_t, MapRelay::iterator>> vRelayExpiration;
} // namespace

namespace {

struct CBlockReject {
    unsigned char chRejectCode;
    std::string strRejectReason;
    uint256 hashBlock;
};

struct CNodeState {
    const CService address;
    bool fCurrentlyConnected;
    int nMisbehavior;
    bool fShouldBan;
    const std::string name;
    std::vector<CBlockReject> rejects;
    const CBlockIndex *pindexBestKnownBlock;
    uint256 hashLastUnknownBlock;
    const CBlockIndex *pindexLastCommonBlock;
    const CBlockIndex *pindexBestHeaderSent;
    int nUnconnectingHeaders;
    bool fSyncStarted;
    int64_t nHeadersSyncTimeout;
    int64_t nStallingSince;
    std::list<QueuedBlock> vBlocksInFlight;
    int64_t nDownloadingSince;
    int nBlocksInFlight;
    int nBlocksInFlightValidHeaders;
    bool fPreferredDownload;
    bool fPreferHeaders;
    bool fPreferHeaderAndIDs;
    bool fProvidesHeaderAndIDs;
    bool fSupportsDesiredCmpctVersion;

    struct ChainSyncTimeoutState {
        int64_t m_timeout;
        const CBlockIndex * m_work_header;
        bool m_sent_getheaders;
        bool m_protect;
    };

    ChainSyncTimeoutState m_chain_sync;

    int64_t m_last_block_announcement;

    /*
     * State associated with objects download.
     *
     * Tx download algorithm:
     *
     *   When inv comes in, queue up (process_time, inv) inside the peer's
     *   CNodeState (m_object_process_time) as long as m_object_announced for the peer
     *   isn't too big (MAX_PEER_OBJECT_ANNOUNCEMENTS).
     *
     *   The process_time for a objects is set to nNow for outbound peers,
     *   nNow + 2 seconds for inbound peers. This is the time at which we'll
     *   consider trying to request the objects from the peer in
     *   SendMessages(). The delay for inbound peers is to allow outbound peers
     *   a chance to announce before we request from inbound peers, to prevent
     *   an adversary from using inbound connections to blind us to a
     *   objects (InvBlock).
     *
     *   When we call SendMessages() for a given peer,
     *   we will loop over the objects in m_object_process_time, looking
     *   at the objects whose process_time <= nNow. We'll request each
     *   such objects that we don't have already and that hasn't been
     *   requested from another peer recently, up until we hit the
     *   MAX_PEER_OBJECT_IN_FLIGHT limit for the peer. Then we'll update
     *   g_already_asked_for for each requested inv, storing the time of the
     *   GETDATA request. We use g_already_asked_for to coordinate objects
     *   requests amongst our peers.
     *
     *   For objects that we still need but we have already recently
     *   requested from some other peer, we'll reinsert (process_time, inv)
     *   back into the peer's m_object_process_time at the point in the future at
     *   which the most recent GETDATA request would time out (ie
     *   GetObjectInterval + the request time stored in g_already_asked_for).
     *   We add an additional delay for inbound peers, again to prefer
     *   attempting download from outbound peers first.
     *   We also add an extra small random delay up to 2 seconds
     *   to avoid biasing some peers over others. (e.g., due to fixed ordering
     *   of peer processing in ThreadMessageHandler).
     *
     *   When we receive a objects from a peer, we remove the inv from the
     *   peer's m_object_in_flight set and from their recently announced set
     *   (m_object_announced).  We also clear g_already_asked_for for that entry, so
     *   that if somehow the objects is not accepted but also not added to
     *   the reject filter, then we will eventually redownload from other
     *   peers.
     */
    struct ObjectDownloadState {
        /* Track when to attempt download of announced objects (process
         * time in micros -> inv)
         */
        std::multimap<std::chrono::microseconds, CInv> m_object_process_time;

        std::set<CInv> m_object_announced;

        std::map<CInv, std::chrono::microseconds> m_object_in_flight;

        std::chrono::microseconds m_check_expiry_timer{0};
    };

    ObjectDownloadState m_object_download;

    CNodeState(CAddress addrIn, std::string addrNameIn) : address(addrIn), name(addrNameIn) {
        fCurrentlyConnected = false;
        nMisbehavior = 0;
        fShouldBan = false;
        pindexBestKnownBlock = nullptr;
        hashLastUnknownBlock.SetNull();
        pindexLastCommonBlock = nullptr;
        pindexBestHeaderSent = nullptr;
        nUnconnectingHeaders = 0;
        fSyncStarted = false;
        nHeadersSyncTimeout = 0;
        nStallingSince = 0;
        nDownloadingSince = 0;
        nBlocksInFlight = 0;
        nBlocksInFlightValidHeaders = 0;
        fPreferredDownload = false;
        fPreferHeaders = false;
        fPreferHeaderAndIDs = false;
        fProvidesHeaderAndIDs = false;
        fSupportsDesiredCmpctVersion = false;
        m_chain_sync = { 0, nullptr, false, false };
        m_last_block_announcement = 0;
    }
};

// Keeps track of the time (in microseconds) when transactions were requested last time
unordered_limitedmap<uint256, std::chrono::microseconds, StaticSaltedHasher> g_already_asked_for(MAX_INV_SZ, MAX_INV_SZ * 2);
unordered_limitedmap<uint256, std::chrono::microseconds, StaticSaltedHasher> g_erased_object_requests(MAX_INV_SZ, MAX_INV_SZ * 2);

std::map<NodeId, CNodeState> mapNodeState;

// Requires cs_main.
CNodeState *State(NodeId pnode) {
    std::map<NodeId, CNodeState>::iterator it = mapNodeState.find(pnode);
    if (it == mapNodeState.end())
        return nullptr;
    return &it->second;
}

void UpdatePreferredDownload(CNode* node, CNodeState* state)
{
    nPreferredDownload -= state->fPreferredDownload;

    // Whether this node should be marked as a preferred download node.
    state->fPreferredDownload = (!node->fInbound || node->fWhitelisted) && !node->fOneShot && !node->fClient;

    nPreferredDownload += state->fPreferredDownload;
}

void PushNodeVersion(CNode *pnode, CConnman* connman, int64_t nTime)
{
    const auto& params = Params();

    ServiceFlags nLocalNodeServices = pnode->GetLocalServices();
    uint64_t nonce = pnode->GetLocalNonce();
    int nNodeStartingHeight = pnode->GetMyStartingHeight();
    NodeId nodeid = pnode->GetId();
    CAddress addr = pnode->addr;

    CAddress addrYou = (addr.IsRoutable() && !IsProxy(addr) ? addr : CAddress(CService(), addr.nServices));
    CAddress addrMe = CAddress(CService(), nLocalNodeServices);

    uint256 mnauthChallenge;
    GetRandBytes(mnauthChallenge.begin(), mnauthChallenge.size());
    {
        LOCK(pnode->cs_mnauth);
        pnode->sentMNAuthChallenge = mnauthChallenge;
    }

    int nProtocolVersion = PROTOCOL_VERSION;
    if (params.NetworkIDString() != CBaseChainParams::MAIN && gArgs.IsArgSet("-pushversion")) {
        nProtocolVersion = gArgs.GetArg("-pushversion", PROTOCOL_VERSION);
    }

    connman->PushMessage(pnode, CNetMsgMaker(INIT_PROTO_VERSION).Make(NetMsgType::VERSION, nProtocolVersion, (uint64_t)nLocalNodeServices, nTime, addrYou, addrMe,
            nonce, strSubVersion, nNodeStartingHeight, ::fRelayTxes, mnauthChallenge, pnode->fMasternode));

    if (fLogIPs) {
        LogPrint(BCLog::NET, "send version message: version %d, blocks=%d, us=%s, them=%s, peer=%d\n", nProtocolVersion, nNodeStartingHeight, addrMe.ToString(), addrYou.ToString(), nodeid);
    } else {
        LogPrint(BCLog::NET, "send version message: version %d, blocks=%d, us=%s, peer=%d\n", nProtocolVersion, nNodeStartingHeight, addrMe.ToString(), nodeid);
    }
}

// Requires cs_main.
// Returns a bool indicating whether we requested this block.
// Also used if a block was /not/ received and timed out or started with another peer
bool MarkBlockAsReceived(const uint256& hash) {
    std::map<uint256, std::pair<NodeId, std::list<QueuedBlock>::iterator> >::iterator itInFlight = mapBlocksInFlight.find(hash);
    if (itInFlight != mapBlocksInFlight.end()) {
        CNodeState *state = State(itInFlight->second.first);
        assert(state != nullptr);
        state->nBlocksInFlightValidHeaders -= itInFlight->second.second->fValidatedHeaders;
        if (state->nBlocksInFlightValidHeaders == 0 && itInFlight->second.second->fValidatedHeaders) {
            // Last validated block on the queue was received.
            nPeersWithValidatedDownloads--;
        }
        if (state->vBlocksInFlight.begin() == itInFlight->second.second) {
            // First block on the queue was received, update the start download time for the next one
            state->nDownloadingSince = std::max(state->nDownloadingSince, GetTimeMicros());
        }
        state->vBlocksInFlight.erase(itInFlight->second.second);
        state->nBlocksInFlight--;
        state->nStallingSince = 0;
        mapBlocksInFlight.erase(itInFlight);
        return true;
    }
    return false;
}

// Requires cs_main.
// returns false, still setting pit, if the block was already in flight from the same peer
// pit will only be valid as long as the same cs_main lock is being held
bool MarkBlockAsInFlight(NodeId nodeid, const uint256& hash, const CBlockIndex *pindex = nullptr, std::list<QueuedBlock>::iterator **pit = nullptr) {
    CNodeState *state = State(nodeid);
    assert(state != nullptr);

    // Short-circuit most stuff in case its from the same node
    std::map<uint256, std::pair<NodeId, std::list<QueuedBlock>::iterator> >::iterator itInFlight = mapBlocksInFlight.find(hash);
    if (itInFlight != mapBlocksInFlight.end() && itInFlight->second.first == nodeid) {
        if (pit) {
            *pit = &itInFlight->second.second;
        }
        return false;
    }

    // Make sure it's not listed somewhere already.
    MarkBlockAsReceived(hash);

    std::list<QueuedBlock>::iterator it = state->vBlocksInFlight.insert(state->vBlocksInFlight.end(),
            {hash, pindex, pindex != nullptr, std::unique_ptr<PartiallyDownloadedBlock>(pit ? new PartiallyDownloadedBlock(&mempool) : nullptr)});
    state->nBlocksInFlight++;
    state->nBlocksInFlightValidHeaders += it->fValidatedHeaders;
    if (state->nBlocksInFlight == 1) {
        // We're starting a block download (batch) from this peer.
        state->nDownloadingSince = GetTimeMicros();
    }
    if (state->nBlocksInFlightValidHeaders == 1 && pindex != nullptr) {
        nPeersWithValidatedDownloads++;
    }
    itInFlight = mapBlocksInFlight.insert(std::make_pair(hash, std::make_pair(nodeid, it))).first;
    if (pit)
        *pit = &itInFlight->second.second;
    return true;
}

void ProcessBlockAvailability(NodeId nodeid) {
    CNodeState *state = State(nodeid);
    assert(state != nullptr);

    if (!state->hashLastUnknownBlock.IsNull()) {
        BlockMap::iterator itOld = mapBlockIndex.find(state->hashLastUnknownBlock);
        if (itOld != mapBlockIndex.end() && itOld->second->nChainWork > 0) {
            if (state->pindexBestKnownBlock == nullptr || itOld->second->nChainWork >= state->pindexBestKnownBlock->nChainWork)
                state->pindexBestKnownBlock = itOld->second;
            state->hashLastUnknownBlock.SetNull();
        }
    }
}

void UpdateBlockAvailability(NodeId nodeid, const uint256 &hash) {
    CNodeState *state = State(nodeid);
    assert(state != nullptr);

    ProcessBlockAvailability(nodeid);

    BlockMap::iterator it = mapBlockIndex.find(hash);
    if (it != mapBlockIndex.end() && it->second->nChainWork > 0) {
        // An actually better block was announced.
        if (state->pindexBestKnownBlock == nullptr || it->second->nChainWork >= state->pindexBestKnownBlock->nChainWork)
            state->pindexBestKnownBlock = it->second;
    } else {
        // An unknown block was announced; just assume that the latest one is the best one.
        state->hashLastUnknownBlock = hash;
    }
}

void MaybeSetPeerAsAnnouncingHeaderAndIDs(NodeId nodeid, CConnman* connman) {
    AssertLockHeld(cs_main);
    CNodeState* nodestate = State(nodeid);
    if (!nodestate || !nodestate->fSupportsDesiredCmpctVersion) {
        // Never ask from peers who can't provide desired version.
        return;
    }
    if (nodestate->fProvidesHeaderAndIDs) {
        for (std::list<NodeId>::iterator it = lNodesAnnouncingHeaderAndIDs.begin(); it != lNodesAnnouncingHeaderAndIDs.end(); it++) {
            if (*it == nodeid) {
                lNodesAnnouncingHeaderAndIDs.erase(it);
                lNodesAnnouncingHeaderAndIDs.push_back(nodeid);
                return;
            }
        }
        connman->ForNode(nodeid, [connman](CNode* pfrom){
            uint64_t nCMPCTBLOCKVersion = 1;
            if (lNodesAnnouncingHeaderAndIDs.size() >= 3) {
                // As per BIP152, we only get 3 of our peers to announce
                // blocks using compact encodings.
                connman->ForNode(lNodesAnnouncingHeaderAndIDs.front(), [connman, nCMPCTBLOCKVersion](CNode* pnodeStop){
                    connman->PushMessage(pnodeStop, CNetMsgMaker(pnodeStop->GetSendVersion()).Make(NetMsgType::SENDCMPCT, /*fAnnounceUsingCMPCTBLOCK=*/false, nCMPCTBLOCKVersion));
                    return true;
                });
                lNodesAnnouncingHeaderAndIDs.pop_front();
            }
            connman->PushMessage(pfrom, CNetMsgMaker(pfrom->GetSendVersion()).Make(NetMsgType::SENDCMPCT, /*fAnnounceUsingCMPCTBLOCK=*/true, nCMPCTBLOCKVersion));
            lNodesAnnouncingHeaderAndIDs.push_back(pfrom->GetId());
            return true;
        });
    }
}

bool TipMayBeStale(const Consensus::Params &consensusParams)
{
    AssertLockHeld(cs_main);
    if (g_last_tip_update == 0) {
        g_last_tip_update = GetTime();
    }
    return g_last_tip_update < GetTime() - consensusParams.nPowTargetSpacing * 3 && mapBlocksInFlight.empty();
}

// Requires cs_main
bool CanDirectFetch(const Consensus::Params &consensusParams)
{
    return chainActive.Tip()->GetBlockTime() > GetAdjustedTime() - consensusParams.nPowTargetSpacing * 20;
}

// Requires cs_main
bool PeerHasHeader(CNodeState *state, const CBlockIndex *pindex)
{
    if (state->pindexBestKnownBlock && pindex == state->pindexBestKnownBlock->GetAncestor(pindex->nHeight))
        return true;
    if (state->pindexBestHeaderSent && pindex == state->pindexBestHeaderSent->GetAncestor(pindex->nHeight))
        return true;
    return false;
}

void FindNextBlocksToDownload(NodeId nodeid, unsigned int count, std::vector<const CBlockIndex*>& vBlocks, NodeId& nodeStaller, const Consensus::Params& consensusParams) {
    if (count == 0)
        return;

    vBlocks.reserve(vBlocks.size() + count);
    CNodeState *state = State(nodeid);
    assert(state != nullptr);

    // Make sure pindexBestKnownBlock is up to date, we'll need it.
    ProcessBlockAvailability(nodeid);

    if (state->pindexBestKnownBlock == nullptr || state->pindexBestKnownBlock->nChainWork < chainActive.Tip()->nChainWork || state->pindexBestKnownBlock->nChainWork < nMinimumChainWork) {
        // This peer has nothing interesting.
        return;
    }

    if (state->pindexLastCommonBlock == nullptr) {
        // Bootstrap quickly by guessing a parent of our best tip is the forking point.
        // Guessing wrong in either direction is not a problem.
        state->pindexLastCommonBlock = chainActive[std::min(state->pindexBestKnownBlock->nHeight, chainActive.Height())];
    }

    // If the peer reorganized, our previous pindexLastCommonBlock may not be an ancestor
    // of its current tip anymore. Go back enough to fix that.
    state->pindexLastCommonBlock = LastCommonAncestor(state->pindexLastCommonBlock, state->pindexBestKnownBlock);
    if (state->pindexLastCommonBlock == state->pindexBestKnownBlock)
        return;

    std::vector<const CBlockIndex*> vToFetch;
    const CBlockIndex *pindexWalk = state->pindexLastCommonBlock;
    // Never fetch further than the best block we know the peer has, or more than BLOCK_DOWNLOAD_WINDOW + 1 beyond the last
    // linked block we have in common with this peer. The +1 is so we can detect stalling, namely if we would be able to
    // download that next block if the window were 1 larger.
    int nWindowEnd = state->pindexLastCommonBlock->nHeight + BLOCK_DOWNLOAD_WINDOW;
    int nMaxHeight = std::min<int>(state->pindexBestKnownBlock->nHeight, nWindowEnd + 1);
    NodeId waitingfor = -1;
    while (pindexWalk->nHeight < nMaxHeight) {
        // Read up to 128 (or more, if more blocks than that are needed) successors of pindexWalk (towards
        // pindexBestKnownBlock) into vToFetch. We fetch 128, because CBlockIndex::GetAncestor may be as expensive
        // as iterating over ~100 CBlockIndex* entries anyway.
        int nToFetch = std::min(nMaxHeight - pindexWalk->nHeight, std::max<int>(count - vBlocks.size(), 128));
        vToFetch.resize(nToFetch);
        pindexWalk = state->pindexBestKnownBlock->GetAncestor(pindexWalk->nHeight + nToFetch);
        vToFetch[nToFetch - 1] = pindexWalk;
        for (unsigned int i = nToFetch - 1; i > 0; i--) {
            vToFetch[i - 1] = vToFetch[i]->pprev;
        }

        // Iterate over those blocks in vToFetch (in forward direction), adding the ones that
        // are not yet downloaded and not in flight to vBlocks. In the mean time, update
        // pindexLastCommonBlock as long as all ancestors are already downloaded, or if it's
        // already part of our chain (and therefore don't need it even if pruned).
        for (const CBlockIndex* pindex : vToFetch) {
            if (!pindex->IsValid(BLOCK_VALID_TREE)) {
                // We consider the chain that this peer is on invalid.
                return;
            }
            if (pindex->nStatus & BLOCK_HAVE_DATA || chainActive.Contains(pindex)) {
                if (pindex->nChainTx)
                    state->pindexLastCommonBlock = pindex;
            } else if (mapBlocksInFlight.count(pindex->GetBlockHash()) == 0) {
                // The block is not already downloaded, and not yet in flight.
                if (pindex->nHeight > nWindowEnd) {
                    // We reached the end of the window.
                    if (vBlocks.size() == 0 && waitingfor != nodeid) {
                        // We aren't able to fetch anything, but we would be if the download window was one larger.
                        nodeStaller = waitingfor;
                    }
                    return;
                }
                vBlocks.push_back(pindex);
                if (vBlocks.size() == count) {
                    return;
                }
            } else if (waitingfor == -1) {
                // This is the first already-in-flight block.
                waitingfor = mapBlocksInFlight[pindex->GetBlockHash()].first;
            }
        }
    }
}
} // namespace

void EraseObjectRequest(CNodeState* nodestate, const CInv& inv) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
{
    AssertLockHeld(cs_main);
    LogPrint(BCLog::NET, "%s -- inv=(%s)\n", __func__, inv.ToString());
    g_already_asked_for.erase(inv.hash);
    g_erased_object_requests.insert(std::make_pair(inv.hash, GetTime<std::chrono::microseconds>()));

    if (nodestate) {
        nodestate->m_object_download.m_object_announced.erase(inv);
        nodestate->m_object_download.m_object_in_flight.erase(inv);
    }
}

void EraseObjectRequest(NodeId nodeId, const CInv& inv) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
{
    AssertLockHeld(cs_main);
    auto* state = State(nodeId);
    if (!state) {
        return;
    }
    EraseObjectRequest(state, inv);
}

std::chrono::microseconds GetObjectRequestTime(const uint256& hash) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
{
    AssertLockHeld(cs_main);
    auto it = g_already_asked_for.find(hash);
    if (it != g_already_asked_for.end()) {
        return it->second;
    }
    return {};
}

void UpdateObjectRequestTime(const uint256& hash, std::chrono::microseconds request_time) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
{
    AssertLockHeld(cs_main);
    auto it = g_already_asked_for.find(hash);
    if (it == g_already_asked_for.end()) {
        g_already_asked_for.insert(std::make_pair(hash, request_time));
    } else {
        g_already_asked_for.update(it, request_time);
    }
}

std::chrono::microseconds GetObjectInterval(int invType)
{
    // some messages need to be re-requested faster when the first announcing peer did not answer to GETDATA
    switch(invType)
    {
        case MSG_QUORUM_RECOVERED_SIG:
            return std::chrono::seconds{15};
        case MSG_CLSIG:
            return std::chrono::seconds{5};
        case MSG_ISLOCK:
            return std::chrono::seconds{10};
        default:
            return GETDATA_TX_INTERVAL;
    }
}

std::chrono::microseconds GetObjectExpiryInterval(int invType)
{
    return GetObjectInterval(invType) * TX_EXPIRY_INTERVAL_FACTOR;
}

std::chrono::microseconds GetObjectRandomDelay(int invType)
{
    if (invType == MSG_TX) {
        return GetRandMicros(MAX_GETDATA_RANDOM_DELAY);
    }
    return {};
}

std::chrono::microseconds CalculateObjectGetDataTime(const CInv& inv, std::chrono::microseconds current_time, bool use_inbound_delay) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
{
    AssertLockHeld(cs_main);
    std::chrono::microseconds process_time;
    const auto last_request_time = GetObjectRequestTime(inv.hash);
    // First time requesting this tx
    if (last_request_time.count() == 0) {
        process_time = current_time;
    } else {
        // Randomize the delay to avoid biasing some peers over others (such as due to
        // fixed ordering of peer processing in ThreadMessageHandler)
        process_time = last_request_time + GetObjectInterval(inv.type) + GetObjectRandomDelay(inv.type);
    }

    // We delay processing announcements from inbound peers
    if (inv.type == MSG_TX && !fMasternodeMode && use_inbound_delay) process_time += INBOUND_PEER_TX_DELAY;

    return process_time;
}

void RequestObject(CNodeState* state, const CInv& inv, std::chrono::microseconds current_time, bool fForce = false) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
{
    AssertLockHeld(cs_main);
    CNodeState::ObjectDownloadState& peer_download_state = state->m_object_download;
    if (peer_download_state.m_object_announced.size() >= MAX_PEER_OBJECT_ANNOUNCEMENTS ||
            peer_download_state.m_object_process_time.size() >= MAX_PEER_OBJECT_ANNOUNCEMENTS ||
            peer_download_state.m_object_announced.count(inv)) {
        // Too many queued announcements from this peer, or we already have
        // this announcement
        return;
    }
    peer_download_state.m_object_announced.insert(inv);

    // Calculate the time to try requesting this transaction. Use
    // fPreferredDownload as a proxy for outbound peers.
    std::chrono::microseconds process_time = CalculateObjectGetDataTime(inv, current_time, !state->fPreferredDownload);

    peer_download_state.m_object_process_time.emplace(process_time, inv);

    if (fForce) {
        // make sure this object is actually requested ASAP
        g_erased_object_requests.erase(inv.hash);
        g_already_asked_for.erase(inv.hash);
    }

    LogPrint(BCLog::NET, "%s -- inv=(%s), current_time=%d, process_time=%d, delta=%d\n", __func__, inv.ToString(), current_time.count(), process_time.count(), (process_time - current_time).count());
}

void RequestObject(NodeId nodeId, const CInv& inv, std::chrono::microseconds current_time, bool fForce) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
{
    AssertLockHeld(cs_main);
    auto* state = State(nodeId);
    if (!state) {
        return;
    }
    RequestObject(state, inv, current_time, fForce);
}

size_t GetRequestedObjectCount(NodeId nodeId)
{
    AssertLockHeld(cs_main);
    auto* state = State(nodeId);
    if (!state) {
        return 0;
    }
    return state->m_object_download.m_object_process_time.size();
}

// This function is used for testing the stale tip eviction logic, see
// DoS_tests.cpp
void UpdateLastBlockAnnounceTime(NodeId node, int64_t time_in_seconds)
{
    LOCK(cs_main);
    CNodeState *state = State(node);
    if (state) state->m_last_block_announcement = time_in_seconds;
}

// Returns true for outbound peers, excluding manual connections, feelers, and
// one-shots
bool IsOutboundDisconnectionCandidate(const CNode *node)
{
    return !(node->fInbound || node->m_manual_connection || node->fFeeler || node->fOneShot);
}

void PeerLogicValidation::InitializeNode(CNode *pnode) {
    CAddress addr = pnode->addr;
    std::string addrName = pnode->GetAddrName();
    NodeId nodeid = pnode->GetId();
    {
        LOCK(cs_main);
        mapNodeState.emplace_hint(mapNodeState.end(), std::piecewise_construct, std::forward_as_tuple(nodeid), std::forward_as_tuple(addr, std::move(addrName)));
    }
    if(!pnode->fInbound)
        PushNodeVersion(pnode, connman, GetTime());
}

void PeerLogicValidation::FinalizeNode(NodeId nodeid, bool& fUpdateConnectionTime) {
    fUpdateConnectionTime = false;
    LOCK(cs_main);
    CNodeState *state = State(nodeid);
    assert(state != nullptr);

    if (state->fSyncStarted)
        nSyncStarted--;

    if (state->nMisbehavior == 0 && state->fCurrentlyConnected) {
        fUpdateConnectionTime = true;
    }

    for (const QueuedBlock& entry : state->vBlocksInFlight) {
        mapBlocksInFlight.erase(entry.hash);
    }
    EraseOrphansFor(nodeid);
    nPreferredDownload -= state->fPreferredDownload;
    nPeersWithValidatedDownloads -= (state->nBlocksInFlightValidHeaders != 0);
    assert(nPeersWithValidatedDownloads >= 0);
    g_outbound_peers_with_protect_from_disconnect -= state->m_chain_sync.m_protect;
    assert(g_outbound_peers_with_protect_from_disconnect >= 0);

    mapNodeState.erase(nodeid);

    if (mapNodeState.empty()) {
        // Do a consistency check after the last peer is removed.
        assert(mapBlocksInFlight.empty());
        assert(nPreferredDownload == 0);
        assert(nPeersWithValidatedDownloads == 0);
        assert(g_outbound_peers_with_protect_from_disconnect == 0);
    }
    LogPrint(BCLog::NET, "Cleared nodestate for peer=%d\n", nodeid);
}

bool GetNodeStateStats(NodeId nodeid, CNodeStateStats &stats) {
    LOCK(cs_main);
    CNodeState *state = State(nodeid);
    if (state == nullptr)
        return false;
    stats.nMisbehavior = state->nMisbehavior;
    stats.nSyncHeight = state->pindexBestKnownBlock ? state->pindexBestKnownBlock->nHeight : -1;
    stats.nCommonHeight = state->pindexLastCommonBlock ? state->pindexLastCommonBlock->nHeight : -1;
    for (const QueuedBlock& queue : state->vBlocksInFlight) {
        if (queue.pindex)
            stats.vHeightInFlight.push_back(queue.pindex->nHeight);
    }
    return true;
}

//
// mapOrphanTransactions
//

void AddToCompactExtraTransactions(const CTransactionRef& tx) EXCLUSIVE_LOCKS_REQUIRED(g_cs_orphans)
{
    size_t max_extra_txn = gArgs.GetArg("-blockreconstructionextratxn", DEFAULT_BLOCK_RECONSTRUCTION_EXTRA_TXN);
    if (max_extra_txn <= 0)
        return;
    if (!vExtraTxnForCompact.size())
        vExtraTxnForCompact.resize(max_extra_txn);
    vExtraTxnForCompact[vExtraTxnForCompactIt] = std::make_pair(tx->GetHash(), tx);
    vExtraTxnForCompactIt = (vExtraTxnForCompactIt + 1) % max_extra_txn;
}

bool AddOrphanTx(const CTransactionRef& tx, NodeId peer) EXCLUSIVE_LOCKS_REQUIRED(g_cs_orphans)
{
    const uint256& hash = tx->GetHash();
    if (mapOrphanTransactions.count(hash))
        return false;

    // Ignore big transactions, to avoid a
    // send-big-orphans memory exhaustion attack. If a peer has a legitimate
    // large transaction with a missing parent then we assume
    // it will rebroadcast it later, after the parent transaction(s)
    // have been mined or received.
    // 100 orphans, each of which is at most 99,999 bytes big is
    // at most 10 megabytes of orphans and somewhat more byprev index (in the worst case):
    unsigned int sz = GetSerializeSize(*tx, SER_NETWORK, CTransaction::CURRENT_VERSION);
    if (sz > MAX_STANDARD_TX_SIZE)
    {
        LogPrint(BCLog::MEMPOOL, "ignoring large orphan tx (size: %u, hash: %s)\n", sz, hash.ToString());
        return false;
    }

    auto ret = mapOrphanTransactions.emplace(hash, COrphanTx{tx, peer, GetTime() + ORPHAN_TX_EXPIRE_TIME, sz});
    assert(ret.second);
    for (const CTxIn& txin : tx->vin) {
        mapOrphanTransactionsByPrev[txin.prevout].insert(ret.first);
    }

    AddToCompactExtraTransactions(tx);

    nMapOrphanTransactionsSize += sz;

    LogPrint(BCLog::MEMPOOL, "stored orphan tx %s (mapsz %u outsz %u)\n", hash.ToString(),
             mapOrphanTransactions.size(), mapOrphanTransactionsByPrev.size());
    return true;
}

int static EraseOrphanTx(uint256 hash) EXCLUSIVE_LOCKS_REQUIRED(g_cs_orphans)
{
    std::map<uint256, COrphanTx>::iterator it = mapOrphanTransactions.find(hash);
    if (it == mapOrphanTransactions.end())
        return 0;
    for (const CTxIn& txin : it->second.tx->vin)
    {
        auto itPrev = mapOrphanTransactionsByPrev.find(txin.prevout);
        if (itPrev == mapOrphanTransactionsByPrev.end())
            continue;
        itPrev->second.erase(it);
        if (itPrev->second.empty())
            mapOrphanTransactionsByPrev.erase(itPrev);
    }
    assert(nMapOrphanTransactionsSize >= it->second.nTxSize);
    nMapOrphanTransactionsSize -= it->second.nTxSize;
    mapOrphanTransactions.erase(it);
    return 1;
}

void EraseOrphansFor(NodeId peer)
{
    LOCK(g_cs_orphans);
    int nErased = 0;
    std::map<uint256, COrphanTx>::iterator iter = mapOrphanTransactions.begin();
    while (iter != mapOrphanTransactions.end())
    {
        std::map<uint256, COrphanTx>::iterator maybeErase = iter++; // increment to avoid iterator becoming invalid
        if (maybeErase->second.fromPeer == peer)
        {
            nErased += EraseOrphanTx(maybeErase->second.tx->GetHash());
        }
    }
    if (nErased > 0) LogPrint(BCLog::MEMPOOL, "Erased %d orphan tx from peer=%d\n", nErased, peer);
}


unsigned int LimitOrphanTxSize(unsigned int nMaxOrphansSize)
{
    LOCK(g_cs_orphans);

    unsigned int nEvicted = 0;
    static int64_t nNextSweep;
    int64_t nNow = GetTime();
    if (nNextSweep <= nNow) {
        // Sweep out expired orphan pool entries:
        int nErased = 0;
        int64_t nMinExpTime = nNow + ORPHAN_TX_EXPIRE_TIME - ORPHAN_TX_EXPIRE_INTERVAL;
        std::map<uint256, COrphanTx>::iterator iter = mapOrphanTransactions.begin();
        while (iter != mapOrphanTransactions.end())
        {
            std::map<uint256, COrphanTx>::iterator maybeErase = iter++;
            if (maybeErase->second.nTimeExpire <= nNow) {
                nErased += EraseOrphanTx(maybeErase->second.tx->GetHash());
            } else {
                nMinExpTime = std::min(maybeErase->second.nTimeExpire, nMinExpTime);
            }
        }
        // Sweep again 5 minutes after the next entry that expires in order to batch the linear scan.
        nNextSweep = nMinExpTime + ORPHAN_TX_EXPIRE_INTERVAL;
        if (nErased > 0) LogPrint(BCLog::MEMPOOL, "Erased %d orphan tx due to expiration\n", nErased);
    }
    while (!mapOrphanTransactions.empty() && nMapOrphanTransactionsSize > nMaxOrphansSize)
    {
        // Evict a random orphan:
        uint256 randomhash = GetRandHash();
        std::map<uint256, COrphanTx>::iterator it = mapOrphanTransactions.lower_bound(randomhash);
        if (it == mapOrphanTransactions.end())
            it = mapOrphanTransactions.begin();
        EraseOrphanTx(it->first);
        ++nEvicted;
    }
    return nEvicted;
}

void static ProcessOrphanTx(CConnman* connman, std::set<uint256>& orphan_work_set) EXCLUSIVE_LOCKS_REQUIRED(cs_main, g_cs_orphans);

// Requires cs_main.
void Misbehaving(NodeId pnode, int howmuch, const std::string& message)
{
    if (howmuch == 0)
        return;

    CNodeState *state = State(pnode);
    if (state == nullptr)
        return;

    state->nMisbehavior += howmuch;
    int banscore = gArgs.GetArg("-banscore", DEFAULT_BANSCORE_THRESHOLD);
    std::string message_prefixed = message.empty() ? "" : (": " + message);
    if (state->nMisbehavior >= banscore && state->nMisbehavior - howmuch < banscore)
    {
        LogPrint(BCLog::NET, "%s: %s peer=%d (%d -> %d) BAN THRESHOLD EXCEEDED%s\n", __func__, state->name, pnode, state->nMisbehavior-howmuch, state->nMisbehavior, message_prefixed);
        state->fShouldBan = true;
    } else
        LogPrint(BCLog::NET, "%s: %s peer=%d (%d -> %d)%s\n", __func__, state->name, pnode, state->nMisbehavior-howmuch, state->nMisbehavior, message_prefixed);
}

// Requires cs_main.
bool IsBanned(NodeId pnode)
{
    CNodeState *state = State(pnode);
    if (state == nullptr)
        return false;
    if (state->fShouldBan) {
        return true;
    }
    return false;
}






//
// blockchain -> download logic notification
//

// To prevent fingerprinting attacks, only send blocks/headers outside of the
// active chain if they are no more than a month older (both in time, and in
// best equivalent proof of work) than the best header chain we know about and
// we fully-validated them at some point.
static bool BlockRequestAllowed(const CBlockIndex* pindex, const Consensus::Params& consensusParams)
{
    AssertLockHeld(cs_main);
    if (chainActive.Contains(pindex)) return true;
    return pindex->IsValid(BLOCK_VALID_SCRIPTS) && (pindexBestHeader != nullptr) &&
        (pindexBestHeader->GetBlockTime() - pindex->GetBlockTime() < STALE_RELAY_AGE_LIMIT) &&
        (GetBlockProofEquivalentTime(*pindexBestHeader, *pindex, *pindexBestHeader, consensusParams) < STALE_RELAY_AGE_LIMIT);
}

PeerLogicValidation::PeerLogicValidation(CConnman* connmanIn, CScheduler &scheduler) : connman(connmanIn), m_stale_tip_check_time(0) {
    // Initialize global variables that cannot be constructed at startup.
    recentRejects.reset(new CRollingBloomFilter(120000, 0.000001));

    const Consensus::Params& consensusParams = Params().GetConsensus();
    // Stale tip checking and peer eviction are on two different timers, but we
    // don't want them to get out of sync due to drift in the scheduler, so we
    // combine them in one function and schedule at the quicker (peer-eviction)
    // timer.
    static_assert(EXTRA_PEER_CHECK_INTERVAL < STALE_CHECK_INTERVAL, "peer eviction timer should be less than stale tip check timer");
    scheduler.scheduleEvery(std::bind(&PeerLogicValidation::CheckForStaleTipAndEvictPeers, this, consensusParams), EXTRA_PEER_CHECK_INTERVAL * 1000);
}

void PeerLogicValidation::BlockConnected(const std::shared_ptr<const CBlock>& pblock, const CBlockIndex* pindex, const std::vector<CTransactionRef>& vtxConflicted) {
    LOCK2(cs_main, g_cs_orphans);

    std::vector<uint256> vOrphanErase;
    std::set<uint256> orphanWorkSet;

    for (const CTransactionRef& ptx : pblock->vtx) {
        const CTransaction& tx = *ptx;

        // Which orphan pool entries we should reprocess and potentially try to accept into mempool again?
        for (size_t i = 0; i < tx.vin.size(); i++) {
            auto itByPrev = mapOrphanTransactionsByPrev.find(COutPoint(tx.GetHash(), (uint32_t)i));
            if (itByPrev == mapOrphanTransactionsByPrev.end()) continue;
            for (const auto& elem : itByPrev->second) {
                orphanWorkSet.insert(elem->first);
            }
        }

        // Which orphan pool entries must we evict?
        for (const auto& txin : tx.vin) {
            auto itByPrev = mapOrphanTransactionsByPrev.find(txin.prevout);
            if (itByPrev == mapOrphanTransactionsByPrev.end()) continue;
            for (auto mi = itByPrev->second.begin(); mi != itByPrev->second.end(); ++mi) {
                const CTransaction& orphanTx = *(*mi)->second.tx;
                const uint256& orphanHash = orphanTx.GetHash();
                vOrphanErase.push_back(orphanHash);
            }
        }
    }

    // Erase orphan transactions include or precluded by this block
    if (vOrphanErase.size()) {
        int nErased = 0;
        for (uint256 &orphanHash : vOrphanErase) {
            nErased += EraseOrphanTx(orphanHash);
        }
        LogPrint(BCLog::MEMPOOL, "Erased %d orphan tx included or conflicted by block\n", nErased);
    }

    while (!orphanWorkSet.empty()) {
        LogPrint(BCLog::MEMPOOL, "Trying to process %d orphans\n", orphanWorkSet.size());
        ProcessOrphanTx(g_connman.get(), orphanWorkSet);
    }

    g_last_tip_update = GetTime();
}

// All of the following cache a recent block, and are protected by cs_most_recent_block
static CCriticalSection cs_most_recent_block;
static std::shared_ptr<const CBlock> most_recent_block;
static std::shared_ptr<const CBlockHeaderAndShortTxIDs> most_recent_compact_block;
static uint256 most_recent_block_hash;

void PeerLogicValidation::NewPoWValidBlock(const CBlockIndex *pindex, const std::shared_ptr<const CBlock>& pblock) {
    std::shared_ptr<const CBlockHeaderAndShortTxIDs> pcmpctblock = std::make_shared<const CBlockHeaderAndShortTxIDs> (*pblock);
    const CNetMsgMaker msgMaker(PROTOCOL_VERSION);

    LOCK(cs_main);

    static int nHighestFastAnnounce = 0;
    if (pindex->nHeight <= nHighestFastAnnounce)
        return;
    nHighestFastAnnounce = pindex->nHeight;

    uint256 hashBlock(pblock->GetHash());

    {
        LOCK(cs_most_recent_block);
        most_recent_block_hash = hashBlock;
        most_recent_block = pblock;
        most_recent_compact_block = pcmpctblock;
    }

    connman->ForEachNode([this, &pcmpctblock, pindex, &msgMaker, &hashBlock](CNode* pnode) {
        // TODO: Avoid the repeated-serialization here
        if (pnode->fDisconnect)
            return;
        ProcessBlockAvailability(pnode->GetId());
        CNodeState &state = *State(pnode->GetId());
        // If the peer has, or we announced to them the previous block already,
        // but we don't think they have this one, go ahead and announce it
        if (state.fPreferHeaderAndIDs &&
                !PeerHasHeader(&state, pindex) && PeerHasHeader(&state, pindex->pprev)) {

            LogPrint(BCLog::NET, "%s sending header-and-ids %s to peer=%d\n", "PeerLogicValidation::NewPoWValidBlock",
                    hashBlock.ToString(), pnode->GetId());
            connman->PushMessage(pnode, msgMaker.Make(NetMsgType::CMPCTBLOCK, *pcmpctblock));
            state.pindexBestHeaderSent = pindex;
        }
    });
}

void PeerLogicValidation::UpdatedBlockTip(const CBlockIndex *pindexNew, const CBlockIndex *pindexFork, bool fInitialDownload) {
    const int nNewHeight = pindexNew->nHeight;
    connman->SetBestHeight(nNewHeight);

    SetServiceFlagsIBDCache(!fInitialDownload);
    if (!fInitialDownload) {
        // Find the hashes of all blocks that weren't previously in the best chain.
        std::vector<uint256> vHashes;
        const CBlockIndex *pindexToAnnounce = pindexNew;
        while (pindexToAnnounce != pindexFork) {
            vHashes.push_back(pindexToAnnounce->GetBlockHash());
            pindexToAnnounce = pindexToAnnounce->pprev;
            if (vHashes.size() == MAX_BLOCKS_TO_ANNOUNCE) {
                // Limit announcements in case of a huge reorganization.
                // Rely on the peer's synchronization mechanism in that case.
                break;
            }
        }
        // Relay inventory, but don't relay old inventory during initial block download.
        connman->ForEachNode([nNewHeight, &vHashes](CNode* pnode) {
            if (pnode->fMasternode) return;
            if (nNewHeight > (pnode->nStartingHeight != -1 ? pnode->nStartingHeight - 2000 : 0)) {
                for (const uint256& hash : reverse_iterate(vHashes)) {
                    pnode->PushBlockHash(hash);
                }
            }
        });
        connman->WakeMessageHandler();
    }

    nTimeBestReceived = GetTime();
}

void PeerLogicValidation::BlockChecked(const CBlock& block, const CValidationState& state) {
    LOCK(cs_main);

    const uint256 hash(block.GetHash());
    std::map<uint256, std::pair<NodeId, bool> >::iterator it = mapBlockSource.find(hash);

    int nDoS = 0;
    if (state.IsInvalid(nDoS)) {
        // Don't send reject message with code 0 or an internal reject code.
        if (it != mapBlockSource.end() && State(it->second.first) && state.GetRejectCode() > 0 && state.GetRejectCode() < REJECT_INTERNAL) {
            CBlockReject reject = {(unsigned char)state.GetRejectCode(), state.GetRejectReason().substr(0, MAX_REJECT_MESSAGE_LENGTH), hash};
            State(it->second.first)->rejects.push_back(reject);
            if (nDoS > 0 && it->second.second)
                Misbehaving(it->second.first, nDoS);
        }
    }
    // Check that:
    // 1. The block is valid
    // 2. We're not in initial block download
    // 3. This is currently the best block we're aware of. We haven't updated
    //    the tip yet so we have no way to check this directly here. Instead we
    //    just check that there are currently no other blocks in flight.
    else if (state.IsValid() &&
             !IsInitialBlockDownload() &&
             mapBlocksInFlight.count(hash) == mapBlocksInFlight.size()) {
        if (it != mapBlockSource.end()) {
            MaybeSetPeerAsAnnouncingHeaderAndIDs(it->second.first, connman);
        }
    }
    if (it != mapBlockSource.end())
        mapBlockSource.erase(it);
}

//
// Messages
//


bool static AlreadyHave(const CInv& inv) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
{
    switch (inv.type)
    {
    case MSG_TX:
    case MSG_DSTX:
    case MSG_LEGACY_TXLOCK_REQUEST: // we treat legacy IX messages as TX messages
        {
            assert(recentRejects);
            if (chainActive.Tip()->GetBlockHash() != hashRecentRejectsChainTip)
            {
                // If the chain tip has changed previously rejected transactions
                // might be now valid, e.g. due to a nLockTime'd tx becoming valid,
                // or a double-spend. Reset the rejects filter and give those
                // txs a second chance.
                hashRecentRejectsChainTip = chainActive.Tip()->GetBlockHash();
                recentRejects->reset();
            }

            {
                LOCK(g_cs_orphans);
                if (mapOrphanTransactions.count(inv.hash)) return true;
            }

            // When we receive an islock for a previously rejected transaction, we have to
            // drop the first-seen tx (which such a locked transaction was conflicting with)
            // and re-request the locked transaction (which did not make it into the mempool
            // previously due to txn-mempool-conflict rule). This means that we must ignore
            // recentRejects filter for such locked txes here.
            // We also ignore recentRejects filter for DSTX-es because a malicious peer  might
            // relay a valid DSTX as a regular TX first which would skip all the specific checks
            // but would cause such tx to be rejected by ATMP due to 0 fee. Ignoring it here
            // should let DSTX to be propagated by honest peer later. Note, that a malicious
            // masternode would not be able to exploit this to spam the network with specially
            // crafted invalid DSTX-es and potentially cause high load cheaply, because
            // corresponding checks in ProcessMessage won't let it to send DSTX-es too often.
            bool fIgnoreRecentRejects = llmq::quorumInstantSendManager->IsLocked(inv.hash) || inv.type == MSG_DSTX;

            return (!fIgnoreRecentRejects && recentRejects->contains(inv.hash)) ||
                   (inv.type == MSG_DSTX && static_cast<bool>(CPrivateSend::GetDSTX(inv.hash))) ||
                   mempool.exists(inv.hash) ||
                   pcoinsTip->HaveCoinInCache(COutPoint(inv.hash, 0)) || // Best effort: only try output 0 and 1
                   pcoinsTip->HaveCoinInCache(COutPoint(inv.hash, 1)) ||
                   (fTxIndex && pblocktree->HasTxIndex(inv.hash));
        }

    case MSG_BLOCK:
        return mapBlockIndex.count(inv.hash);

    /*
        Dash Related Inventory Messages

        --

        We shouldn't update the sync times for each of the messages when we already have it.
        We're going to be asking many nodes upfront for the full inventory list, so we'll get duplicates of these.
        We want to only update the time on new hits, so that we can time out appropriately if needed.
    */

    case MSG_SPORK:
        {
            CSporkMessage spork;
            return sporkManager.GetSporkByHash(inv.hash, spork);
        }

    case MSG_GOVERNANCE_OBJECT:
    case MSG_GOVERNANCE_OBJECT_VOTE:
        return ! governance.ConfirmInventoryRequest(inv);

    case MSG_QUORUM_FINAL_COMMITMENT:
        return llmq::quorumBlockProcessor->HasMinableCommitment(inv.hash);
    case MSG_QUORUM_CONTRIB:
    case MSG_QUORUM_COMPLAINT:
    case MSG_QUORUM_JUSTIFICATION:
    case MSG_QUORUM_PREMATURE_COMMITMENT:
        return llmq::quorumDKGSessionManager->AlreadyHave(inv);
    case MSG_QUORUM_RECOVERED_SIG:
        return llmq::quorumSigningManager->AlreadyHave(inv);
    case MSG_CLSIG:
        return llmq::chainLocksHandler->AlreadyHave(inv);
    case MSG_ISLOCK:
        return llmq::quorumInstantSendManager->AlreadyHave(inv);
    }

    // Don't know what it is, just say we already got one
    return true;
}

static void RelayAddress(const CAddress& addr, bool fReachable, CConnman* connman)
{
    unsigned int nRelayNodes = fReachable ? 2 : 1; // limited relaying of addresses outside our network(s)

    // Relay to a limited number of other nodes
    // Use deterministic randomness to send to the same nodes for 24 hours
    // at a time so the addrKnowns of the chosen nodes prevent repeats
    uint64_t hashAddr = addr.GetHash();
    const CSipHasher hasher = connman->GetDeterministicRandomizer(RANDOMIZER_ID_ADDRESS_RELAY).Write(hashAddr << 32).Write((GetTime() + hashAddr) / (24*60*60));
    FastRandomContext insecure_rand;

    std::array<std::pair<uint64_t, CNode*>,2> best{{{0, nullptr}, {0, nullptr}}};
    assert(nRelayNodes <= best.size());

    auto sortfunc = [&best, &hasher, nRelayNodes](CNode* pnode) {
        if (pnode->nVersion >= CADDR_TIME_VERSION) {
            uint64_t hashKey = CSipHasher(hasher).Write(pnode->GetId()).Finalize();
            for (unsigned int i = 0; i < nRelayNodes; i++) {
                if (hashKey > best[i].first) {
                    std::copy(best.begin() + i, best.begin() + nRelayNodes - 1, best.begin() + i + 1);
                    best[i] = std::make_pair(hashKey, pnode);
                    break;
                }
            }
        }
    };

    auto pushfunc = [&addr, &best, nRelayNodes, &insecure_rand] {
        for (unsigned int i = 0; i < nRelayNodes && best[i].first != 0; i++) {
            best[i].second->PushAddress(addr, insecure_rand);
        }
    };

    connman->ForEachNodeThen(std::move(sortfunc), std::move(pushfunc));
}

void static ProcessGetBlockData(CNode* pfrom, const CChainParams& chainparams, const CInv& inv, CConnman* connman, const std::atomic<bool>& interruptMsgProc)
{
    bool send = false;
    std::shared_ptr<const CBlock> a_recent_block;
    std::shared_ptr<const CBlockHeaderAndShortTxIDs> a_recent_compact_block;
    const Consensus::Params& consensusParams = chainparams.GetConsensus();
    {
        LOCK(cs_most_recent_block);
        a_recent_block = most_recent_block;
        a_recent_compact_block = most_recent_compact_block;
    }

    bool need_activate_chain = false;
    {
        LOCK(cs_main);
        BlockMap::iterator mi = mapBlockIndex.find(inv.hash);
        if (mi != mapBlockIndex.end())
        {
            if (mi->second->nChainTx && !mi->second->IsValid(BLOCK_VALID_SCRIPTS) &&
                    mi->second->IsValid(BLOCK_VALID_TREE)) {
                // If we have the block and all of its parents, but have not yet validated it,
                // we might be in the middle of connecting it (ie in the unlock of cs_main
                // before ActivateBestChain but after AcceptBlock).
                // In this case, we need to run ActivateBestChain prior to checking the relay
                // conditions below.
                need_activate_chain = true;
            }
        }
    } // release cs_main before calling ActivateBestChain
    if (need_activate_chain) {
        CValidationState dummy;
        ActivateBestChain(dummy, Params(), a_recent_block);
    }

    LOCK(cs_main);
    BlockMap::iterator mi = mapBlockIndex.find(inv.hash);
    if (mi != mapBlockIndex.end()) {
        send = BlockRequestAllowed(mi->second, consensusParams);
        if (!send) {
            LogPrint(BCLog::NET,"%s: ignoring request from peer=%i for old block that isn't in the main chain\n", __func__, pfrom->GetId());
        }
    }
    const CNetMsgMaker msgMaker(pfrom->GetSendVersion());
    // disconnect node in case we have reached the outbound limit for serving historical blocks
    // never disconnect whitelisted nodes
    if (send && connman->OutboundTargetReached(true) && ( ((pindexBestHeader != nullptr) && (pindexBestHeader->GetBlockTime() - mi->second->GetBlockTime() > HISTORICAL_BLOCK_AGE)) || inv.type == MSG_FILTERED_BLOCK) && !pfrom->fWhitelisted)
    {
        LogPrint(BCLog::NET, "historical block serving limit reached, disconnect peer=%d\n", pfrom->GetId());

        //disconnect node
        pfrom->fDisconnect = true;
        send = false;
    }
    // Avoid leaking prune-height by never sending blocks below the NODE_NETWORK_LIMITED threshold
    if (send && !pfrom->fWhitelisted && (
            (((pfrom->GetLocalServices() & NODE_NETWORK_LIMITED) == NODE_NETWORK_LIMITED) && ((pfrom->GetLocalServices() & NODE_NETWORK) != NODE_NETWORK) && (chainActive.Tip()->nHeight - mi->second->nHeight > (int)NODE_NETWORK_LIMITED_MIN_BLOCKS + 2 /* add two blocks buffer extension for possible races */) )
       )) {
        LogPrint(BCLog::NET, "Ignore block request below NODE_NETWORK_LIMITED threshold from peer=%d\n", pfrom->GetId());

        //disconnect node and prevent it from stalling (would otherwise wait for the missing block)
        pfrom->fDisconnect = true;
        send = false;
    }
    // Pruned nodes may have deleted the block, so check whether
    // it's available before trying to send.
    if (send && (mi->second->nStatus & BLOCK_HAVE_DATA))
    {
        std::shared_ptr<const CBlock> pblock;
        if (a_recent_block && a_recent_block->GetHash() == (*mi).second->GetBlockHash()) {
            pblock = a_recent_block;
        } else {
            // Send block from disk
            std::shared_ptr<CBlock> pblockRead = std::make_shared<CBlock>();
            if (!ReadBlockFromDisk(*pblockRead, (*mi).second, consensusParams))
                assert(!"cannot load block from disk");
            pblock = pblockRead;
        }
        if (pblock) {
            if (inv.type == MSG_BLOCK)
                connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::BLOCK, *pblock));
            else if (inv.type == MSG_FILTERED_BLOCK) {
                bool sendMerkleBlock = false;
                CMerkleBlock merkleBlock;
                {
                    LOCK(pfrom->cs_filter);
                    if (pfrom->pfilter) {
                        sendMerkleBlock = true;
                        merkleBlock = CMerkleBlock(*pblock, *pfrom->pfilter);
                    }
                }
                if (sendMerkleBlock) {
                    connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::MERKLEBLOCK, merkleBlock));
                    // CMerkleBlock just contains hashes, so also push any transactions in the block the client did not see
                    // This avoids hurting performance by pointlessly requiring a round-trip
                    // Note that there is currently no way for a node to request any single transactions we didn't send here -
                    // they must either disconnect and retry or request the full block.
                    // Thus, the protocol spec specified allows for us to provide duplicate txn here,
                    // however we MUST always provide at least what the remote peer needs
                    typedef std::pair<unsigned int, uint256> PairType;
                    for (PairType &pair : merkleBlock.vMatchedTxn)
                        connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::TX, *pblock->vtx[pair.first]));
                }
                // else
                // no response
            } else if (inv.type == MSG_CMPCT_BLOCK) {
                // If a peer is asking for old blocks, we're almost guaranteed
                // they won't have a useful mempool to match against a compact block,
                // and we don't feel like constructing the object for them, so
                // instead we respond with the full, non-compact block.
                if (CanDirectFetch(consensusParams) &&
                    mi->second->nHeight >= chainActive.Height() - MAX_CMPCTBLOCK_DEPTH) {
                    if (a_recent_compact_block &&
                        a_recent_compact_block->header.GetHash() == mi->second->GetBlockHash()) {
                        connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::CMPCTBLOCK, *a_recent_compact_block));
                    } else {
                        CBlockHeaderAndShortTxIDs cmpctblock(*pblock);
                        connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::CMPCTBLOCK, cmpctblock));
                    }
                } else {
                    connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::BLOCK, *pblock));
                }
            }
        }
        // Trigger the peer node to send a getblocks request for the next batch of inventory
        if (inv.hash == pfrom->hashContinue)
        {
            // Bypass PushInventory, this must send even if redundant,
            // and we want it right after the last block so they don't
            // wait for other stuff first.
            std::vector<CInv> vInv;
            vInv.push_back(CInv(MSG_BLOCK, chainActive.Tip()->GetBlockHash()));
            connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::INV, vInv));
            pfrom->hashContinue.SetNull();
        }
    }
}

void static ProcessGetData(CNode* pfrom, const CChainParams& chainparams, CConnman* connman, const std::atomic<bool>& interruptMsgProc)
{
    AssertLockNotHeld(cs_main);

    std::deque<CInv>::iterator it = pfrom->vRecvGetData.begin();
    std::vector<CInv> vNotFound;
    const CNetMsgMaker msgMaker(pfrom->GetSendVersion());
    {
        LOCK(cs_main);

        while (it != pfrom->vRecvGetData.end() && it->IsKnownType()) {
            if (interruptMsgProc)
                return;
            // Don't bother if send buffer is too full to respond anyway
            if (pfrom->fPauseSend)
                break;

            const CInv &inv = *it;
            if (inv.type == MSG_BLOCK || inv.type == MSG_FILTERED_BLOCK || inv.type == MSG_CMPCT_BLOCK) {
                break;
            }
            it++;

            // Send stream from relay memory
            bool push = false;
            if (inv.type == MSG_TX || inv.type == MSG_DSTX) {
                CPrivateSendBroadcastTx dstx;
                if (inv.type == MSG_DSTX) {
                    dstx = CPrivateSend::GetDSTX(inv.hash);
                }
                auto mi = mapRelay.find(inv.hash);
                if (mi != mapRelay.end()) {
                    if (dstx) {
                        connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::DSTX, dstx));
                    } else {
                        connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::TX, *mi->second));
                    }
                    push = true;
                } else if (pfrom->timeLastMempoolReq) {
                    auto txinfo = mempool.info(inv.hash);
                    // To protect privacy, do not answer getdata using the mempool when
                    // that TX couldn't have been INVed in reply to a MEMPOOL request.
                    if (txinfo.tx && txinfo.nTime <= pfrom->timeLastMempoolReq) {
                        if (dstx) {
                            connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::DSTX, dstx));
                        } else {
                            connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::TX, *txinfo.tx));
                        }
                        push = true;
                    }
                }
            }

            if (!push && inv.type == MSG_SPORK) {
                CSporkMessage spork;
                if(sporkManager.GetSporkByHash(inv.hash, spork)) {
                    connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::SPORK, spork));
                    push = true;
                }
            }

            if (!push && inv.type == MSG_GOVERNANCE_OBJECT) {
                LogPrint(BCLog::NET, "ProcessGetData -- MSG_GOVERNANCE_OBJECT: inv = %s\n", inv.ToString());
                CDataStream ss(SER_NETWORK, pfrom->GetSendVersion());
                bool topush = false;
                {
                    if(governance.HaveObjectForHash(inv.hash)) {
                        ss.reserve(1000);
                        if(governance.SerializeObjectForHash(inv.hash, ss)) {
                            topush = true;
                        }
                    }
                }
                LogPrint(BCLog::NET, "ProcessGetData -- MSG_GOVERNANCE_OBJECT: topush = %d, inv = %s\n", topush, inv.ToString());
                if(topush) {
                    connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::MNGOVERNANCEOBJECT, ss));
                    push = true;
                }
            }

            if (!push && inv.type == MSG_GOVERNANCE_OBJECT_VOTE) {
                CDataStream ss(SER_NETWORK, pfrom->GetSendVersion());
                bool topush = false;
                {
                    if(governance.HaveVoteForHash(inv.hash)) {
                        ss.reserve(1000);
                        if(governance.SerializeVoteForHash(inv.hash, ss)) {
                            topush = true;
                        }
                    }
                }
                if(topush) {
                    LogPrint(BCLog::NET, "ProcessGetData -- pushing: inv = %s\n", inv.ToString());
                    connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::MNGOVERNANCEOBJECTVOTE, ss));
                    push = true;
                }
            }

            if (!push && (inv.type == MSG_QUORUM_FINAL_COMMITMENT)) {
                llmq::CFinalCommitment o;
                if (llmq::quorumBlockProcessor->GetMinableCommitmentByHash(inv.hash, o)) {
                    connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::QFCOMMITMENT, o));
                    push = true;
                }
            }

            if (!push && (inv.type == MSG_QUORUM_CONTRIB)) {
                llmq::CDKGContribution o;
                if (llmq::quorumDKGSessionManager->GetContribution(inv.hash, o)) {
                    connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::QCONTRIB, o));
                    push = true;
                }
            }
            if (!push && (inv.type == MSG_QUORUM_COMPLAINT)) {
                llmq::CDKGComplaint o;
                if (llmq::quorumDKGSessionManager->GetComplaint(inv.hash, o)) {
                    connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::QCOMPLAINT, o));
                    push = true;
                }
            }
            if (!push && (inv.type == MSG_QUORUM_JUSTIFICATION)) {
                llmq::CDKGJustification o;
                if (llmq::quorumDKGSessionManager->GetJustification(inv.hash, o)) {
                    connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::QJUSTIFICATION, o));
                    push = true;
                }
            }
            if (!push && (inv.type == MSG_QUORUM_PREMATURE_COMMITMENT)) {
                llmq::CDKGPrematureCommitment o;
                if (llmq::quorumDKGSessionManager->GetPrematureCommitment(inv.hash, o)) {
                    connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::QPCOMMITMENT, o));
                    push = true;
                }
            }
            if (!push && (inv.type == MSG_QUORUM_RECOVERED_SIG)) {
                llmq::CRecoveredSig o;
                if (llmq::quorumSigningManager->GetRecoveredSigForGetData(inv.hash, o)) {
                    connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::QSIGREC, o));
                    push = true;
                }
            }

            if (!push && (inv.type == MSG_CLSIG)) {
                llmq::CChainLockSig o;
                if (llmq::chainLocksHandler->GetChainLockByHash(inv.hash, o)) {
                    connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::CLSIG, o));
                    push = true;
                }
            }

            if (!push && (inv.type == MSG_ISLOCK)) {
                llmq::CInstantSendLock o;
                if (llmq::quorumInstantSendManager->GetInstantSendLockByHash(inv.hash, o)) {
                    connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::ISLOCK, o));
                    push = true;
                }
            }

            if (!push)
                vNotFound.push_back(inv);
        }
    } // release cs_main

    if (it != pfrom->vRecvGetData.end() && !pfrom->fPauseSend) {
        const CInv &inv = *it;
        if (inv.type == MSG_BLOCK || inv.type == MSG_FILTERED_BLOCK || inv.type == MSG_CMPCT_BLOCK) {
            it++;
            ProcessGetBlockData(pfrom, chainparams, inv, connman, interruptMsgProc);
        }
    }

    pfrom->vRecvGetData.erase(pfrom->vRecvGetData.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
        // about (and store and rebroadcast and risk analyze) the dependencies
        // of transactions relevant to them, without having to download the
        // entire memory pool.
        // Also, other nodes can use these messages to automatically request a
        // transaction from some other peer that annnounced it, and stop
        // waiting for us to respond.
        // In normal operation, we often send NOTFOUND messages for parents of
        // transactions that we relay; if a peer is missing a parent, they may
        // assume we have them and request the parents from us.
        connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::NOTFOUND, vNotFound));
    }
}

inline void static SendBlockTransactions(const CBlock& block, const BlockTransactionsRequest& req, CNode* pfrom, CConnman* connman) {
    BlockTransactions resp(req);
    for (size_t i = 0; i < req.indexes.size(); i++) {
        if (req.indexes[i] >= block.vtx.size()) {
            LOCK(cs_main);
            Misbehaving(pfrom->GetId(), 100, strprintf("Peer %d sent us a getblocktxn with out-of-bounds tx indices", pfrom->GetId()));
            return;
        }
        resp.txn[i] = block.vtx[req.indexes[i]];
    }
    LOCK(cs_main);
    CNetMsgMaker msgMaker(pfrom->GetSendVersion());
    connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::BLOCKTXN, resp));
}

bool static ProcessHeadersMessage(CNode *pfrom, CConnman *connman, const std::vector<CBlockHeader>& headers, const CChainParams& chainparams, bool punish_duplicate_invalid)
{
    const CNetMsgMaker msgMaker(pfrom->GetSendVersion());
    size_t nCount = headers.size();

    if (nCount == 0) {
        // Nothing interesting. Stop asking this peers for more headers.
        return true;
    }

    bool received_new_header = false;
    const CBlockIndex *pindexLast = nullptr;
    {
        LOCK(cs_main);
        CNodeState *nodestate = State(pfrom->GetId());

        // If this looks like it could be a block announcement (nCount <
        // MAX_BLOCKS_TO_ANNOUNCE), use special logic for handling headers that
        // don't connect:
        // - Send a getheaders message in response to try to connect the chain.
        // - The peer can send up to MAX_UNCONNECTING_HEADERS in a row that
        //   don't connect before giving DoS points
        // - Once a headers message is received that is valid and does connect,
        //   nUnconnectingHeaders gets reset back to 0.
        if (mapBlockIndex.find(headers[0].hashPrevBlock) == mapBlockIndex.end() && nCount < MAX_BLOCKS_TO_ANNOUNCE) {
            nodestate->nUnconnectingHeaders++;
            connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::GETHEADERS, chainActive.GetLocator(pindexBestHeader), uint256()));
            LogPrint(BCLog::NET, "received header %s: missing prev block %s, sending getheaders (%d) to end (peer=%d, nUnconnectingHeaders=%d)\n",
                    headers[0].GetHash().ToString(),
                    headers[0].hashPrevBlock.ToString(),
                    pindexBestHeader->nHeight,
                    pfrom->GetId(), nodestate->nUnconnectingHeaders);
            // Set hashLastUnknownBlock for this peer, so that if we
            // eventually get the headers - even from a different peer -
            // we can use this peer to download.
            UpdateBlockAvailability(pfrom->GetId(), headers.back().GetHash());

            if (nodestate->nUnconnectingHeaders % MAX_UNCONNECTING_HEADERS == 0) {
                Misbehaving(pfrom->GetId(), 20);
            }
            return true;
        }

        uint256 hashLastBlock;
        for (const CBlockHeader& header : headers) {
            if (!hashLastBlock.IsNull() && header.hashPrevBlock != hashLastBlock) {
                Misbehaving(pfrom->GetId(), 20, "non-continuous headers sequence");
                return false;
            }
            hashLastBlock = header.GetHash();
        }

        // If we don't have the last header, then they'll have given us
        // something new (if these headers are valid).
        if (mapBlockIndex.find(hashLastBlock) == mapBlockIndex.end()) {
            received_new_header = true;
        }
    }

    CValidationState state;
    CBlockHeader first_invalid_header;
    if (!ProcessNewBlockHeaders(headers, state, chainparams, &pindexLast, &first_invalid_header)) {
        int nDoS;
        if (state.IsInvalid(nDoS)) {
            LOCK(cs_main);
            if (nDoS > 0) {
                Misbehaving(pfrom->GetId(), nDoS, "invalid header received");
            } else {
                LogPrint(BCLog::NET, "peer=%d: invalid header received\n", pfrom->GetId());
            }
            if (punish_duplicate_invalid && mapBlockIndex.find(first_invalid_header.GetHash()) != mapBlockIndex.end()) {
                // Goal: don't allow outbound peers to use up our outbound
                // connection slots if they are on incompatible chains.
                //
                // We ask the caller to set punish_invalid appropriately based
                // on the peer and the method of header delivery (compact
                // blocks are allowed to be invalid in some circumstances,
                // under BIP 152).
                // Here, we try to detect the narrow situation that we have a
                // valid block header (ie it was valid at the time the header
                // was received, and hence stored in mapBlockIndex) but know the
                // block is invalid, and that a peer has announced that same
                // block as being on its active chain.
                // Disconnect the peer in such a situation.
                //
                // Note: if the header that is invalid was not accepted to our
                // mapBlockIndex at all, that may also be grounds for
                // disconnecting the peer, as the chain they are on is likely
                // to be incompatible. However, there is a circumstance where
                // that does not hold: if the header's timestamp is more than
                // 2 hours ahead of our current time. In that case, the header
                // may become valid in the future, and we don't want to
                // disconnect a peer merely for serving us one too-far-ahead
                // block header, to prevent an attacker from splitting the
                // network by mining a block right at the 2 hour boundary.
                //
                // TODO: update the DoS logic (or, rather, rewrite the
                // DoS-interface between validation and net_processing) so that
                // the interface is cleaner, and so that we disconnect on all the
                // reasons that a peer's headers chain is incompatible
                // with ours (eg block->nVersion softforks, MTP violations,
                // etc), and not just the duplicate-invalid case.
                pfrom->fDisconnect = true;
            }
            return false;
        }
    }

    {
        LOCK(cs_main);
        CNodeState *nodestate = State(pfrom->GetId());
        if (nodestate->nUnconnectingHeaders > 0) {
            LogPrint(BCLog::NET, "peer=%d: resetting nUnconnectingHeaders (%d -> 0)\n", pfrom->GetId(), nodestate->nUnconnectingHeaders);
        }
        nodestate->nUnconnectingHeaders = 0;

        assert(pindexLast);
        UpdateBlockAvailability(pfrom->GetId(), pindexLast->GetBlockHash());

        // From here, pindexBestKnownBlock should be guaranteed to be non-null,
        // because it is set in UpdateBlockAvailability. Some nullptr checks
        // are still present, however, as belt-and-suspenders.

        if (received_new_header && pindexLast->nChainWork > chainActive.Tip()->nChainWork) {
            nodestate->m_last_block_announcement = GetTime();
        }

        if (nCount == MAX_HEADERS_RESULTS) {
            // Headers message had its maximum size; the peer may have more headers.
            // TODO: optimize: if pindexLast is an ancestor of chainActive.Tip or pindexBestHeader, continue
            // from there instead.
            LogPrint(BCLog::NET, "more getheaders (%d) to end to peer=%d (startheight:%d)\n", pindexLast->nHeight, pfrom->GetId(), pfrom->nStartingHeight);
            connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::GETHEADERS, chainActive.GetLocator(pindexLast), uint256()));
        }

        bool fCanDirectFetch = CanDirectFetch(chainparams.GetConsensus());
        // If this set of headers is valid and ends in a block with at least as
        // much work as our tip, download as much as possible.
        if (fCanDirectFetch && pindexLast->IsValid(BLOCK_VALID_TREE) && chainActive.Tip()->nChainWork <= pindexLast->nChainWork) {
            std::vector<const CBlockIndex*> vToFetch;
            const CBlockIndex *pindexWalk = pindexLast;
            // Calculate all the blocks we'd need to switch to pindexLast, up to a limit.
            while (pindexWalk && !chainActive.Contains(pindexWalk) && vToFetch.size() <= MAX_BLOCKS_IN_TRANSIT_PER_PEER) {
                if (!(pindexWalk->nStatus & BLOCK_HAVE_DATA) &&
                        !mapBlocksInFlight.count(pindexWalk->GetBlockHash())) {
                    // We don't have this block, and it's not yet in flight.
                    vToFetch.push_back(pindexWalk);
                }
                pindexWalk = pindexWalk->pprev;
            }
            // If pindexWalk still isn't on our main chain, we're looking at a
            // very large reorg at a time we think we're close to caught up to
            // the main chain -- this shouldn't really happen.  Bail out on the
            // direct fetch and rely on parallel download instead.
            if (!chainActive.Contains(pindexWalk)) {
                LogPrint(BCLog::NET, "Large reorg, won't direct fetch to %s (%d)\n",
                        pindexLast->GetBlockHash().ToString(),
                        pindexLast->nHeight);
            } else {
                std::vector<CInv> vGetData;
                // Download as much as possible, from earliest to latest.
                for (const CBlockIndex *pindex : reverse_iterate(vToFetch)) {
                    if (nodestate->nBlocksInFlight >= MAX_BLOCKS_IN_TRANSIT_PER_PEER) {
                        // Can't download any more from this peer
                        break;
                    }
                    vGetData.push_back(CInv(MSG_BLOCK, pindex->GetBlockHash()));
                    MarkBlockAsInFlight(pfrom->GetId(), pindex->GetBlockHash(), pindex);
                    LogPrint(BCLog::NET, "Requesting block %s from  peer=%d\n",
                            pindex->GetBlockHash().ToString(), pfrom->GetId());
                }
                if (vGetData.size() > 1) {
                    LogPrint(BCLog::NET, "Downloading blocks toward %s (%d) via headers direct fetch\n",
                            pindexLast->GetBlockHash().ToString(), pindexLast->nHeight);
                }
                if (vGetData.size() > 0) {
                    if (nodestate->fSupportsDesiredCmpctVersion && vGetData.size() == 1 && mapBlocksInFlight.size() == 1 && pindexLast->pprev->IsValid(BLOCK_VALID_CHAIN)) {
                        // In any case, we want to download using a compact block, not a regular one
                        vGetData[0] = CInv(MSG_CMPCT_BLOCK, vGetData[0].hash);
                    }
                    connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::GETDATA, vGetData));
                }
            }
        }
        // If we're in IBD, we want outbound peers that will serve us a useful
        // chain. Disconnect peers that are on chains with insufficient work.
        if (IsInitialBlockDownload() && nCount != MAX_HEADERS_RESULTS) {
            // When nCount < MAX_HEADERS_RESULTS, we know we have no more
            // headers to fetch from this peer.
            if (nodestate->pindexBestKnownBlock && nodestate->pindexBestKnownBlock->nChainWork < nMinimumChainWork) {
                // This peer has too little work on their headers chain to help
                // us sync -- disconnect if using an outbound slot (unless
                // whitelisted or addnode).
                // Note: We compare their tip to nMinimumChainWork (rather than
                // chainActive.Tip()) because we won't start block download
                // until we have a headers chain that has at least
                // nMinimumChainWork, even if a peer has a chain past our tip,
                // as an anti-DoS measure.
                if (IsOutboundDisconnectionCandidate(pfrom)) {
                    LogPrintf("Disconnecting outbound peer %d -- headers chain has insufficient work\n", pfrom->GetId());
                    pfrom->fDisconnect = true;
                }
            }
        }

        if (!pfrom->fDisconnect && IsOutboundDisconnectionCandidate(pfrom) && nodestate->pindexBestKnownBlock != nullptr) {
            // If this is an outbound peer, check to see if we should protect
            // it from the bad/lagging chain logic.
            if (g_outbound_peers_with_protect_from_disconnect < MAX_OUTBOUND_PEERS_TO_PROTECT_FROM_DISCONNECT && nodestate->pindexBestKnownBlock->nChainWork >= chainActive.Tip()->nChainWork && !nodestate->m_chain_sync.m_protect) {
                LogPrint(BCLog::NET, "Protecting outbound peer=%d from eviction\n", pfrom->GetId());
                nodestate->m_chain_sync.m_protect = true;
                ++g_outbound_peers_with_protect_from_disconnect;
            }
        }
    }

    return true;
}

void static ProcessOrphanTx(CConnman* connman, std::set<uint256>& orphan_work_set) EXCLUSIVE_LOCKS_REQUIRED(cs_main, g_cs_orphans)
{
    AssertLockHeld(cs_main);
    AssertLockHeld(g_cs_orphans);
    std::set<NodeId> setMisbehaving;
    bool done = false;
    while (!done && !orphan_work_set.empty()) {
        const uint256 orphanHash = *orphan_work_set.begin();
        orphan_work_set.erase(orphan_work_set.begin());

        auto orphan_it = mapOrphanTransactions.find(orphanHash);
        if (orphan_it == mapOrphanTransactions.end()) continue;

        const CTransactionRef porphanTx = orphan_it->second.tx;
        const CTransaction& orphanTx = *porphanTx;
        NodeId fromPeer = orphan_it->second.fromPeer;
        bool fMissingInputs2 = false;
        // Use a dummy CValidationState so someone can't setup nodes to counter-DoS based on orphan
        // resolution (that is, feeding people an invalid transaction based on LegitTxX in order to get
        // anyone relaying LegitTxX banned)
        CValidationState stateDummy;

        if (setMisbehaving.count(fromPeer)) continue;
        if (AcceptToMemoryPool(mempool, stateDummy, porphanTx, &fMissingInputs2 /* pfMissingInputs */,
                false /* bypass_limits */, 0 /* nAbsurdFee */)) {
            LogPrint(BCLog::MEMPOOL, "   accepted orphan tx %s\n", orphanHash.ToString());
            connman->RelayTransaction(orphanTx);
            for (unsigned int i = 0; i < orphanTx.vout.size(); i++) {
                auto it_by_prev = mapOrphanTransactionsByPrev.find(COutPoint(orphanHash, i));
                if (it_by_prev != mapOrphanTransactionsByPrev.end()) {
                    for (const auto& elem : it_by_prev->second) {
                        orphan_work_set.insert(elem->first);
                    }
                }
            }
            EraseOrphanTx(orphanHash);
            done = true;
        } else if (!fMissingInputs2) {
            int nDos = 0;
            if (stateDummy.IsInvalid(nDos) && nDos > 0) {
                // Punish peer that gave us an invalid orphan tx
                Misbehaving(fromPeer, nDos);
                setMisbehaving.insert(fromPeer);
                LogPrint(BCLog::MEMPOOL, "   invalid orphan tx %s\n", orphanHash.ToString());
            }
            // Has inputs but not accepted to mempool
            // Probably non-standard or insufficient fee
            LogPrint(BCLog::MEMPOOL, "   removed orphan tx %s\n", orphanHash.ToString());
            if (!stateDummy.CorruptionPossible()) {
                assert(recentRejects);
                recentRejects->insert(orphanHash);
            }
            EraseOrphanTx(orphanHash);
            done = true;
        }
        mempool.check(pcoinsTip.get());
    }
}

bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStream& vRecv, int64_t nTimeReceived, const CChainParams& chainparams, CConnman* connman, const std::atomic<bool>& interruptMsgProc)
{
    LogPrint(BCLog::NET, "received: %s (%u bytes) peer=%d\n", SanitizeString(strCommand), vRecv.size(), pfrom->GetId());
    if (gArgs.IsArgSet("-dropmessagestest") && GetRand(gArgs.GetArg("-dropmessagestest", 0)) == 0)
    {
        LogPrintf("dropmessagestest DROPPING RECV MESSAGE\n");
        return true;
    }

    if (!(pfrom->GetLocalServices() & NODE_BLOOM) &&
              (strCommand == NetMsgType::FILTERLOAD ||
               strCommand == NetMsgType::FILTERADD))
    {
        if (pfrom->nVersion >= NO_BLOOM_VERSION) {
            LOCK(cs_main);
            Misbehaving(pfrom->GetId(), 100);
            return false;
        } else {
            pfrom->fDisconnect = true;
            return false;
        }
    }

    if (strCommand == NetMsgType::REJECT)
    {
        std::string strMsg; unsigned char ccode; std::string strReason;
        uint256 hash;
        try {
            vRecv >> LIMITED_STRING(strMsg, CMessageHeader::COMMAND_SIZE) >> ccode >> LIMITED_STRING(strReason, MAX_REJECT_MESSAGE_LENGTH);
            if (strMsg == NetMsgType::BLOCK || strMsg == NetMsgType::TX) {
                vRecv >> hash;
            }
        } catch (const std::ios_base::failure&) {
            // Avoid feedback loops by preventing reject messages from triggering a new reject message.
            LogPrint(BCLog::NET, "Unparseable reject message received\n");
        }

        if (strMsg == NetMsgType::BLOCK) {
            // The node requested a block from us and then rejected it, which indicates that it's most likely running
            // on rules which are incompatible to ours. Better to ban him after some time as it might otherwise keep
            // asking for the same block (if -addnode/-connect was used on the other side).
            LOCK(cs_main);
            Misbehaving(pfrom->GetId(), 1);
        }

        if (LogAcceptCategory(BCLog::NET)) {
            std::ostringstream ss;
            ss << strMsg << " code " << itostr(ccode) << ": " << strReason;

            if (strMsg == NetMsgType::BLOCK || strMsg == NetMsgType::TX) {
                ss << ": hash " << hash.ToString();
            }
            LogPrint(BCLog::NET, "Reject %s\n", SanitizeString(ss.str()));
        }
        return true;
    }

    if (strCommand == NetMsgType::VERSION) {
        // Each connection can only send one version message
        if (pfrom->nVersion != 0)
        {
            if (g_enable_bip61) {
                connman->PushMessage(pfrom, CNetMsgMaker(INIT_PROTO_VERSION).Make(NetMsgType::REJECT, strCommand, REJECT_DUPLICATE, std::string("Duplicate version message")));
            }
            LOCK(cs_main);
            Misbehaving(pfrom->GetId(), 1);
            return false;
        }

        int64_t nTime;
        CAddress addrMe;
        CAddress addrFrom;
        uint64_t nNonce = 1;
        uint64_t nServiceInt;
        ServiceFlags nServices;
        int nVersion;
        int nSendVersion;
        std::string strSubVer;
        std::string cleanSubVer;
        int nStartingHeight = -1;
        bool fRelay = true;

        vRecv >> nVersion >> nServiceInt >> nTime >> addrMe;
        nSendVersion = std::min(nVersion, PROTOCOL_VERSION);
        nServices = ServiceFlags(nServiceInt);
        if (!pfrom->fInbound)
        {
            connman->SetServices(pfrom->addr, nServices);
        }
        if (!pfrom->fInbound && !pfrom->fFeeler && !pfrom->m_manual_connection && !HasAllDesirableServiceFlags(nServices))
        {
            LogPrint(BCLog::NET, "peer=%d does not offer the expected services (%08x offered, %08x expected); disconnecting\n", pfrom->GetId(), nServices, GetDesirableServiceFlags(nServices));
            if (g_enable_bip61) {
                connman->PushMessage(pfrom, CNetMsgMaker(INIT_PROTO_VERSION).Make(NetMsgType::REJECT, strCommand, REJECT_NONSTANDARD,
                                   strprintf("Expected to offer services %08x", GetDesirableServiceFlags(nServices))));
            }
            pfrom->fDisconnect = true;
            return false;
        }

        if (nVersion < MIN_PEER_PROTO_VERSION)
        {
            // disconnect from peers older than this proto version
            LogPrint(BCLog::NET, "peer=%d using obsolete version %i; disconnecting\n", pfrom->GetId(), nVersion);
            if (g_enable_bip61) {
                connman->PushMessage(pfrom, CNetMsgMaker(INIT_PROTO_VERSION).Make(NetMsgType::REJECT, strCommand, REJECT_OBSOLETE,
                                   strprintf("Version must be %d or greater", MIN_PEER_PROTO_VERSION)));
            }
            pfrom->fDisconnect = true;
            return false;
        }

        if (nVersion == 10300)
            nVersion = 300;
        if (!vRecv.empty())
            vRecv >> addrFrom >> nNonce;
        if (!vRecv.empty()) {
            vRecv >> LIMITED_STRING(strSubVer, MAX_SUBVERSION_LENGTH);
            cleanSubVer = SanitizeString(strSubVer);
        }
        if (!vRecv.empty()) {
            vRecv >> nStartingHeight;
        }
        if (!vRecv.empty())
            vRecv >> fRelay;
        if (!vRecv.empty()) {
            LOCK(pfrom->cs_mnauth);
            vRecv >> pfrom->receivedMNAuthChallenge;
        }
        if (!vRecv.empty()) {
            bool fOtherMasternode = false;
            vRecv >> fOtherMasternode;
            if (pfrom->fInbound) {
                pfrom->fMasternode = fOtherMasternode;
                if (fOtherMasternode) {
                    LogPrint(BCLog::NET_NETCONN, "peer=%d is an inbound masternode connection, not relaying anything to it\n", pfrom->GetId());
                    if (!fMasternodeMode) {
                        LogPrint(BCLog::NET_NETCONN, "but we're not a masternode, disconnecting\n");
                        pfrom->fDisconnect = true;
                        return true;
                    }
                }
            }
        }
        // Disconnect if we connected to ourself
        if (pfrom->fInbound && !connman->CheckIncomingNonce(nNonce))
        {
            LogPrintf("connected to self at %s, disconnecting\n", pfrom->addr.ToString());
            pfrom->fDisconnect = true;
            return true;
        }

        if (pfrom->fInbound && addrMe.IsRoutable())
        {
            SeenLocal(addrMe);
        }

        // Be shy and don't send version until we hear
        if (pfrom->fInbound)
            PushNodeVersion(pfrom, connman, GetAdjustedTime());

        if (Params().NetworkIDString() == CBaseChainParams::DEVNET) {
            if (strSubVer.find(strprintf("devnet=%s", gArgs.GetDevNetName())) == std::string::npos) {
                LOCK(cs_main);
                LogPrintf("connected to wrong devnet. Reported version is %s, expected devnet name is %s\n", strSubVer, gArgs.GetDevNetName());
                if (!pfrom->fInbound)
                    Misbehaving(pfrom->GetId(), 100); // don't try to connect again
                else
                    Misbehaving(pfrom->GetId(), 1); // whover connected, might just have made a mistake, don't ban him immediately
                pfrom->fDisconnect = true;
                return true;
            }
        }

        connman->PushMessage(pfrom, CNetMsgMaker(INIT_PROTO_VERSION).Make(NetMsgType::VERACK));

        pfrom->nServices = nServices;
        pfrom->SetAddrLocal(addrMe);
        {
            LOCK(pfrom->cs_SubVer);
            pfrom->strSubVer = strSubVer;
            pfrom->cleanSubVer = cleanSubVer;
        }
        pfrom->nStartingHeight = nStartingHeight;

        // set nodes not relaying blocks and tx and not serving (parts) of the historical blockchain as "clients"
        pfrom->fClient = (!(nServices & NODE_NETWORK) && !(nServices & NODE_NETWORK_LIMITED));

        // set nodes not capable of serving the complete blockchain history as "limited nodes"
        pfrom->m_limited_node = (!(nServices & NODE_NETWORK) && (nServices & NODE_NETWORK_LIMITED));

        {
            LOCK(pfrom->cs_filter);
            pfrom->fRelayTxes = fRelay; // set to true after we get the first filter* message
        }

        // Change version
        pfrom->SetSendVersion(nSendVersion);
        pfrom->nVersion = nVersion;

        // Potentially mark this peer as a preferred download peer.
        {
        LOCK(cs_main);
        UpdatePreferredDownload(pfrom, State(pfrom->GetId()));
        }

        if (!pfrom->fInbound)
        {
            // Advertise our address
            if (fListen && !IsInitialBlockDownload())
            {
                CAddress addr = GetLocalAddress(&pfrom->addr, pfrom->GetLocalServices());
                FastRandomContext insecure_rand;
                if (addr.IsRoutable())
                {
                    LogPrint(BCLog::NET, "ProcessMessages: advertising address %s\n", addr.ToString());
                    pfrom->PushAddress(addr, insecure_rand);
                } else if (IsPeerAddrLocalGood(pfrom)) {
                    addr.SetIP(addrMe);
                    LogPrint(BCLog::NET, "ProcessMessages: advertising address %s\n", addr.ToString());
                    pfrom->PushAddress(addr, insecure_rand);
                }
            }

            // Get recent addresses
            if (pfrom->fOneShot || pfrom->nVersion >= CADDR_TIME_VERSION || connman->GetAddressCount() < 1000)
            {
                connman->PushMessage(pfrom, CNetMsgMaker(nSendVersion).Make(NetMsgType::GETADDR));
                pfrom->fGetAddr = true;
            }
            connman->MarkAddressGood(pfrom->addr);
        }

        std::string remoteAddr;
        if (fLogIPs)
            remoteAddr = ", peeraddr=" + pfrom->addr.ToString();

        LogPrint(BCLog::NET, "receive version message: %s: version %d, blocks=%d, us=%s, peer=%d%s\n",
                  cleanSubVer, pfrom->nVersion,
                  pfrom->nStartingHeight, addrMe.ToString(), pfrom->GetId(),
                  remoteAddr);

        int64_t nTimeOffset = nTime - GetTime();
        pfrom->nTimeOffset = nTimeOffset;
        AddTimeData(pfrom->addr, nTimeOffset);

        // Feeler connections exist only to verify if address is online.
        if (pfrom->fFeeler) {
            assert(pfrom->fInbound == false);
            pfrom->fDisconnect = true;
        }
        return true;
    }

    if (pfrom->nVersion == 0) {
        // Must have a version message before anything else
        LOCK(cs_main);
        Misbehaving(pfrom->GetId(), 1);
        return false;
    }

    // At this point, the outgoing message serialization version can't change.
    const CNetMsgMaker msgMaker(pfrom->GetSendVersion());

    if (strCommand == NetMsgType::VERACK)
    {
        pfrom->SetRecvVersion(std::min(pfrom->nVersion.load(), PROTOCOL_VERSION));

        if (!pfrom->fInbound) {
            // Mark this node as currently connected, so we update its timestamp later.
            LOCK(cs_main);
            State(pfrom->GetId())->fCurrentlyConnected = true;
            LogPrintf("New outbound peer connected: version: %d, blocks=%d, peer=%d%s\n",
                      pfrom->nVersion.load(), pfrom->nStartingHeight, pfrom->GetId(),
                      (fLogIPs ? strprintf(", peeraddr=%s", pfrom->addr.ToString()) : ""));
        }

        if (pfrom->nVersion >= LLMQS_PROTO_VERSION && !pfrom->fMasternodeProbe) {
            CMNAuth::PushMNAUTH(pfrom, *connman);
        }

        if (pfrom->nVersion >= SENDHEADERS_VERSION) {
            // Tell our peer we prefer to receive headers rather than inv's
            // We send this to non-NODE NETWORK peers as well, because even
            // non-NODE NETWORK peers can announce blocks (such as pruning
            // nodes)
            connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::SENDHEADERS));
        }

        if (pfrom->nVersion >= SHORT_IDS_BLOCKS_VERSION && !pfrom->fMasternode) {
            // Tell our peer we are willing to provide version-1 cmpctblocks
            // However, we do not request new block announcements using
            // cmpctblock messages.
            // We send this to non-NODE NETWORK peers as well, because
            // they may wish to request compact blocks from us
            bool fAnnounceUsingCMPCTBLOCK = false;
            uint64_t nCMPCTBLOCKVersion = 1;
            connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::SENDCMPCT, fAnnounceUsingCMPCTBLOCK, nCMPCTBLOCKVersion));
        }

        if (pfrom->nVersion >= SENDDSQUEUE_PROTO_VERSION) {
            // Tell our peer that he should send us PrivateSend queue messages
            connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::SENDDSQUEUE, true));
        } else {
            // older nodes do not support SENDDSQUEUE and expect us to always send PrivateSend queue messages
            // TODO we can remove this compatibility code in 0.15.0
            pfrom->fSendDSQueue = true;
        }

        if (pfrom->nVersion >= LLMQS_PROTO_VERSION && !pfrom->fMasternode) {
            // Tell our peer that we're interested in plain LLMQ recovered signatures.
            // Otherwise the peer would only announce/send messages resulting from QRECSIG,
            // e.g. InstantSend locks or ChainLocks. SPV nodes should not send this message
            // as they are usually only interested in the higher level messages
            connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::QSENDRECSIGS, true));
        }

        if (gArgs.GetBoolArg("-watchquorums", llmq::DEFAULT_WATCH_QUORUMS) && !pfrom->fMasternode) {
            connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::QWATCH));
        }

        pfrom->fSuccessfullyConnected = true;
        return true;
    }

    if (!pfrom->fSuccessfullyConnected) {
        // Must have a verack message before anything else
        LOCK(cs_main);
        Misbehaving(pfrom->GetId(), 1);
        return false;
    }

    if (pfrom->nTimeFirstMessageReceived == 0) {
        // First message after VERSION/VERACK
        pfrom->nTimeFirstMessageReceived = GetTimeMicros();
        pfrom->fFirstMessageIsMNAUTH = strCommand == NetMsgType::MNAUTH;
        // Note: do not break the flow here

        if (pfrom->fMasternodeProbe && !pfrom->fFirstMessageIsMNAUTH) {
            LogPrint(BCLog::NET, "connection is a masternode probe but first received message is not MNAUTH, peer=%d\n", pfrom->GetId());
            pfrom->fDisconnect = true;
            return false;
        }
    }

    if (strCommand == NetMsgType::ADDR) {
        std::vector<CAddress> vAddr;
        vRecv >> vAddr;

        // Don't want addr from older versions unless seeding
        if (pfrom->nVersion < CADDR_TIME_VERSION && connman->GetAddressCount() > 1000)
            return true;
        if (vAddr.size() > 1000)
        {
            LOCK(cs_main);
            Misbehaving(pfrom->GetId(), 20, strprintf("message addr size() = %u", vAddr.size()));
            return false;
        }

        // Store the new addresses
        std::vector<CAddress> vAddrOk;
        int64_t nNow = GetAdjustedTime();
        int64_t nSince = nNow - 10 * 60;
        for (CAddress& addr : vAddr)
        {
            if (interruptMsgProc)
                return true;

            // We only bother storing full nodes, though this may include
            // things which we would not make an outbound connection to, in
            // part because we may make feeler connections to them.
            if (!MayHaveUsefulAddressDB(addr.nServices) && !HasAllDesirableServiceFlags(addr.nServices))
                continue;

            if (addr.nTime <= 100000000 || addr.nTime > nNow + 10 * 60)
                addr.nTime = nNow - 5 * 24 * 60 * 60;
            pfrom->AddAddressKnown(addr);
            bool fReachable = IsReachable(addr);
            if (addr.nTime > nSince && !pfrom->fGetAddr && vAddr.size() <= 10 && addr.IsRoutable())
            {
                RelayAddress(addr, fReachable, connman);
            }
            // Do not store addresses outside our network
            if (fReachable)
                vAddrOk.push_back(addr);
        }
        connman->AddNewAddresses(vAddrOk, pfrom->addr, 2 * 60 * 60);
        if (vAddr.size() < 1000)
            pfrom->fGetAddr = false;
        if (pfrom->fOneShot)
            pfrom->fDisconnect = true;
        return true;
    }

    if (strCommand == NetMsgType::SENDHEADERS) {
        LOCK(cs_main);
        State(pfrom->GetId())->fPreferHeaders = true;
        return true;
    }

     if (strCommand == NetMsgType::SENDCMPCT) {
        bool fAnnounceUsingCMPCTBLOCK = false;
        uint64_t nCMPCTBLOCKVersion = 1;
        vRecv >> fAnnounceUsingCMPCTBLOCK >> nCMPCTBLOCKVersion;
        if (nCMPCTBLOCKVersion == 1) {
            LOCK(cs_main);
            State(pfrom->GetId())->fProvidesHeaderAndIDs = true;
            State(pfrom->GetId())->fPreferHeaderAndIDs = fAnnounceUsingCMPCTBLOCK;
            State(pfrom->GetId())->fSupportsDesiredCmpctVersion = true;
        }
        return true;
    }


    if (strCommand == NetMsgType::SENDDSQUEUE)
    {
        bool b;
        vRecv >> b;
        pfrom->fSendDSQueue = b;
        return true;
    }


    if (strCommand == NetMsgType::QSENDRECSIGS) {
        bool b;
        vRecv >> b;
        pfrom->fSendRecSigs = b;
        return true;
    }

    if (strCommand == NetMsgType::INV) {
        std::vector<CInv> vInv;
        vRecv >> vInv;
        if (vInv.size() > MAX_INV_SZ)
        {
            LOCK(cs_main);
            Misbehaving(pfrom->GetId(), 20, strprintf("message inv size() = %u", vInv.size()));
            return false;
        }

        bool fBlocksOnly = !fRelayTxes;

        // Allow whitelisted peers to send data other than blocks in blocks only mode if whitelistrelay is true
        if (pfrom->fWhitelisted && gArgs.GetBoolArg("-whitelistrelay", DEFAULT_WHITELISTRELAY))
            fBlocksOnly = false;

        LOCK(cs_main);

        const auto current_time = GetTime<std::chrono::microseconds>();

        for (CInv &inv : vInv)
        {
            if(!inv.IsKnownType()) {
                LogPrint(BCLog::NET, "got inv of unknown type %d: %s peer=%d\n", inv.type, inv.hash.ToString(), pfrom->GetId());
                continue;
            }

            if (interruptMsgProc)
                return true;

            bool fAlreadyHave = AlreadyHave(inv);
            LogPrint(BCLog::NET, "got inv: %s  %s peer=%d\n", inv.ToString(), fAlreadyHave ? "have" : "new", pfrom->GetId());

            if (inv.type == MSG_BLOCK) {
                UpdateBlockAvailability(pfrom->GetId(), inv.hash);

                if (fAlreadyHave || fImporting || fReindex || mapBlocksInFlight.count(inv.hash)) {
                    continue;
                }

                CNodeState *state = State(pfrom->GetId());
                if (!state) {
                    continue;
                }

                // Download if this is a nice peer, or we have no nice peers and this one might do.
                bool fFetch = state->fPreferredDownload || (nPreferredDownload == 0 && !pfrom->fOneShot);
                // Only actively request headers from a single peer, unless we're close to end of initial download.
                if ((nSyncStarted == 0 && fFetch) || pindexBestHeader->GetBlockTime() > GetAdjustedTime() - nMaxTipAge) {
                    // Make sure to mark this peer as the one we are currently syncing with etc.
                    state->fSyncStarted = true;
                    state->nHeadersSyncTimeout = GetTimeMicros() + HEADERS_DOWNLOAD_TIMEOUT_BASE + HEADERS_DOWNLOAD_TIMEOUT_PER_HEADER * (GetAdjustedTime() - pindexBestHeader->GetBlockTime())/(chainparams.GetConsensus().nPowTargetSpacing);
                    nSyncStarted++;
                    // We used to request the full block here, but since headers-announcements are now the
                    // primary method of announcement on the network, and since, in the case that a node
                    // fell back to inv we probably have a reorg which we should get the headers for first,
                    // we now only provide a getheaders response here. When we receive the headers, we will
                    // then ask for the blocks we need.
                    connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::GETHEADERS, chainActive.GetLocator(pindexBestHeader), inv.hash));
                    LogPrint(BCLog::NET, "getheaders (%d) %s to peer=%d\n", pindexBestHeader->nHeight, inv.hash.ToString(), pfrom->GetId());
                }
            }
            else
            {
                static std::set<int> allowWhileInIBDObjs = {
                        MSG_SPORK
                };

                pfrom->AddInventoryKnown(inv);
                if (fBlocksOnly) {
                    LogPrint(BCLog::NET, "transaction (%s) inv sent in violation of protocol peer=%d\n", inv.hash.ToString(),
                             pfrom->GetId());
                } else if (!fAlreadyHave) {
                    bool allowWhileInIBD = allowWhileInIBDObjs.count(inv.type);
                    if (allowWhileInIBD || (!fImporting && !fReindex && !IsInitialBlockDownload())) {
                        RequestObject(State(pfrom->GetId()), inv, current_time);
                    }
                }
            }
        }
        return true;
    }

    if (strCommand == NetMsgType::GETDATA) {
        std::vector<CInv> vInv;
        vRecv >> vInv;
        if (vInv.size() > MAX_INV_SZ)
        {
            LOCK(cs_main);
            Misbehaving(pfrom->GetId(), 20, strprintf("message getdata size() = %u", vInv.size()));
            return false;
        }

        LogPrint(BCLog::NET, "received getdata (%u invsz) peer=%d\n", vInv.size(), pfrom->GetId());

        if (vInv.size() > 0) {
            LogPrint(BCLog::NET, "received getdata for: %s peer=%d\n", vInv[0].ToString(), pfrom->GetId());
        }

        pfrom->vRecvGetData.insert(pfrom->vRecvGetData.end(), vInv.begin(), vInv.end());
        ProcessGetData(pfrom, chainparams, connman, interruptMsgProc);
        return true;
    }

    if (strCommand == NetMsgType::GETBLOCKS) {
        CBlockLocator locator;
        uint256 hashStop;
        vRecv >> locator >> hashStop;

        // We might have announced the currently-being-connected tip using a
        // compact block, which resulted in the peer sending a getblocks
        // request, which we would otherwise respond to without the new block.
        // To avoid this situation we simply verify that we are on our best
        // known chain now. This is super overkill, but we handle it better
        // for getheaders requests, and there are no known nodes which support
        // compact blocks but still use getblocks to request blocks.
        {
            std::shared_ptr<const CBlock> a_recent_block;
            {
                LOCK(cs_most_recent_block);
                a_recent_block = most_recent_block;
            }
            CValidationState dummy;
            ActivateBestChain(dummy, Params(), a_recent_block);
        }

        LOCK(cs_main);

        // Find the last block the caller has in the main chain
        const CBlockIndex* pindex = FindForkInGlobalIndex(chainActive, locator);

        // Send the rest of the chain
        if (pindex)
            pindex = chainActive.Next(pindex);
        int nLimit = 500;
        LogPrint(BCLog::NET, "getblocks %d to %s limit %d from peer=%d\n", (pindex ? pindex->nHeight : -1), hashStop.IsNull() ? "end" : hashStop.ToString(), nLimit, pfrom->GetId());
        for (; pindex; pindex = chainActive.Next(pindex))
        {
            if (pindex->GetBlockHash() == hashStop)
            {
                LogPrint(BCLog::NET, "  getblocks stopping at %d %s\n", pindex->nHeight, pindex->GetBlockHash().ToString());
                break;
            }
            // If pruning, don't inv blocks unless we have on disk and are likely to still have
            // for some reasonable time window (1 hour) that block relay might require.
            const int nPrunedBlocksLikelyToHave = MIN_BLOCKS_TO_KEEP - 3600 / chainparams.GetConsensus().nPowTargetSpacing;
            if (fPruneMode && (!(pindex->nStatus & BLOCK_HAVE_DATA) || pindex->nHeight <= chainActive.Tip()->nHeight - nPrunedBlocksLikelyToHave))
            {
                LogPrint(BCLog::NET, " getblocks stopping, pruned or too old block at %d %s\n", pindex->nHeight, pindex->GetBlockHash().ToString());
                break;
            }
            if (!pfrom->fMasternode) {
                pfrom->PushInventory(CInv(MSG_BLOCK, pindex->GetBlockHash()));
            }
            if (--nLimit <= 0)
            {
                // When this block is requested, we'll send an inv that'll
                // trigger the peer to getblocks the next batch of inventory.
                LogPrint(BCLog::NET, "  getblocks stopping at limit %d %s\n", pindex->nHeight, pindex->GetBlockHash().ToString());
                pfrom->hashContinue = pindex->GetBlockHash();
                break;
            }
        }
        return true;
    }

    if (strCommand == NetMsgType::GETBLOCKTXN) {
        BlockTransactionsRequest req;
        vRecv >> req;

        std::shared_ptr<const CBlock> recent_block;
        {
            LOCK(cs_most_recent_block);
            if (most_recent_block_hash == req.blockhash)
                recent_block = most_recent_block;
            // Unlock cs_most_recent_block to avoid cs_main lock inversion
        }
        if (recent_block) {
            SendBlockTransactions(*recent_block, req, pfrom, connman);
            return true;
        }

        LOCK(cs_main);

        BlockMap::iterator it = mapBlockIndex.find(req.blockhash);
        if (it == mapBlockIndex.end() || !(it->second->nStatus & BLOCK_HAVE_DATA)) {
            LogPrint(BCLog::NET, "Peer %d sent us a getblocktxn for a block we don't have\n", pfrom->GetId());
            return true;
        }

        if (it->second->nHeight < chainActive.Height() - MAX_BLOCKTXN_DEPTH) {
            // If an older block is requested (should never happen in practice,
            // but can happen in tests) send a block response instead of a
            // blocktxn response. Sending a full block response instead of a
            // small blocktxn response is preferable in the case where a peer
            // might maliciously send lots of getblocktxn requests to trigger
            // expensive disk reads, because it will require the peer to
            // actually receive all the data read from disk over the network.
            LogPrint(BCLog::NET, "Peer %d sent us a getblocktxn for a block > %i deep", pfrom->GetId(), MAX_BLOCKTXN_DEPTH);
            CInv inv;
            inv.type = MSG_BLOCK;
            inv.hash = req.blockhash;
            pfrom->vRecvGetData.push_back(inv);
            // The message processing loop will go around again (without pausing) and we'll respond then (without cs_main)
            return true;
        }

        CBlock block;
        bool ret = ReadBlockFromDisk(block, it->second, chainparams.GetConsensus());
        assert(ret);

        SendBlockTransactions(block, req, pfrom, connman);
        return true;
    }

    if (strCommand == NetMsgType::GETHEADERS) {
        CBlockLocator locator;
        uint256 hashStop;
        vRecv >> locator >> hashStop;

        LOCK(cs_main);
        if (IsInitialBlockDownload() && !pfrom->fWhitelisted) {
            LogPrint(BCLog::NET, "Ignoring getheaders from peer=%d because node is in initial block download\n", pfrom->GetId());
            return true;
        }

        CNodeState *nodestate = State(pfrom->GetId());
        const CBlockIndex* pindex = nullptr;
        if (locator.IsNull())
        {
            // If locator is null, return the hashStop block
            BlockMap::iterator mi = mapBlockIndex.find(hashStop);
            if (mi == mapBlockIndex.end())
                return true;
            pindex = (*mi).second;

            if (!BlockRequestAllowed(pindex, chainparams.GetConsensus())) {
                LogPrint(BCLog::NET, "%s: ignoring request from peer=%i for old block header that isn't in the main chain\n", __func__, pfrom->GetId());
                return true;
            }
        }
        else
        {
            // Find the last block the caller has in the main chain
            pindex = FindForkInGlobalIndex(chainActive, locator);
            if (pindex)
                pindex = chainActive.Next(pindex);
        }

        // we must use CBlocks, as CBlockHeaders won't include the 0x00 nTx count at the end
        std::vector<CBlock> vHeaders;
        int nLimit = MAX_HEADERS_RESULTS;
        LogPrint(BCLog::NET, "getheaders %d to %s from peer=%d\n", (pindex ? pindex->nHeight : -1), hashStop.IsNull() ? "end" : hashStop.ToString(), pfrom->GetId());
        for (; pindex; pindex = chainActive.Next(pindex))
        {
            vHeaders.push_back(pindex->GetBlockHeader());
            if (--nLimit <= 0 || pindex->GetBlockHash() == hashStop)
                break;
        }
        // pindex can be nullptr either if we sent chainActive.Tip() OR
        // if our peer has chainActive.Tip() (and thus we are sending an empty
        // headers message). In both cases it's safe to update
        // pindexBestHeaderSent to be our tip.
        //
        // It is important that we simply reset the BestHeaderSent value here,
        // and not max(BestHeaderSent, newHeaderSent). We might have announced
        // the currently-being-connected tip using a compact block, which
        // resulted in the peer sending a headers request, which we respond to
        // without the new block. By resetting the BestHeaderSent, we ensure we
        // will re-announce the new block via headers (or compact blocks again)
        // in the SendMessages logic.
        nodestate->pindexBestHeaderSent = pindex ? pindex : chainActive.Tip();
        connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::HEADERS, vHeaders));
        return true;
    }

    if (strCommand == NetMsgType::TX || strCommand == NetMsgType::DSTX || strCommand == NetMsgType::LEGACYTXLOCKREQUEST) {
        // Stop processing the transaction early if
        // We are in blocks only mode and peer is either not whitelisted or whitelistrelay is off
        if (!fRelayTxes && (!pfrom->fWhitelisted || !gArgs.GetBoolArg("-whitelistrelay", DEFAULT_WHITELISTRELAY)))
        {
            LogPrint(BCLog::NET, "transaction sent in violation of protocol peer=%d\n", pfrom->GetId());
            return true;
        }

        CTransactionRef ptx;
        CPrivateSendBroadcastTx dstx;
        int nInvType = MSG_TX;

        // Read data and assign inv type
        if(strCommand == NetMsgType::TX) {
            vRecv >> ptx;
        } else if(strCommand == NetMsgType::LEGACYTXLOCKREQUEST) {
            // we keep processing the legacy IX message here but revert to handling it as a regular TX
            vRecv >> ptx;
        } else if (strCommand == NetMsgType::DSTX) {
            vRecv >> dstx;
            ptx = dstx.tx;
            nInvType = MSG_DSTX;
        }
        const CTransaction& tx = *ptx;

        CInv inv(nInvType, tx.GetHash());
        pfrom->AddInventoryKnown(inv);

        // Process custom logic, no matter if tx will be accepted to mempool later or not
        if (nInvType == MSG_DSTX) {
            uint256 hashTx = tx.GetHash();
            if (!dstx.IsValidStructure()) {
                LogPrint(BCLog::PRIVATESEND, "DSTX -- Invalid DSTX structure: %s\n", hashTx.ToString());
                return false;
            }
            if(CPrivateSend::GetDSTX(hashTx)) {
                LogPrint(BCLog::PRIVATESEND, "DSTX -- Already have %s, skipping...\n", hashTx.ToString());
                return true; // not an error
            }

            const CBlockIndex* pindex{nullptr};
            CDeterministicMNCPtr dmn{nullptr};
            {
                LOCK(cs_main);
                pindex = chainActive.Tip();
            }
            // It could be that a MN is no longer in the list but its DSTX is not yet mined.
            // Try to find a MN up to 24 blocks deep to make sure such dstx-es are relayed and processed correctly.
            for (int i = 0; i < 24 && pindex; ++i) {
                dmn = deterministicMNManager->GetListForBlock(pindex).GetMNByCollateral(dstx.masternodeOutpoint);
                if (dmn) break;
                pindex = pindex->pprev;
            }
            if(!dmn) {
                LogPrint(BCLog::PRIVATESEND, "DSTX -- Can't find masternode %s to verify %s\n", dstx.masternodeOutpoint.ToStringShort(), hashTx.ToString());
                return false;
            }

            if (!mmetaman.GetMetaInfo(dmn->proTxHash)->IsValidForMixingTxes()) {
                LogPrint(BCLog::PRIVATESEND, "DSTX -- Masternode %s is sending too many transactions %s\n", dstx.masternodeOutpoint.ToStringShort(), hashTx.ToString());
                return true;
                // TODO: Not an error? Could it be that someone is relaying old DSTXes
                // we have no idea about (e.g we were offline)? How to handle them?
            }

            if (!dstx.CheckSignature(dmn->pdmnState->pubKeyOperator.Get())) {
                LogPrint(BCLog::PRIVATESEND, "DSTX -- CheckSignature() failed for %s\n", hashTx.ToString());
                return false;
            }

            LogPrint(BCLog::PRIVATESEND, "DSTX -- Got Masternode transaction %s\n", hashTx.ToString());
            mempool.PrioritiseTransaction(hashTx, 0.1*COIN);
            mmetaman.DisallowMixing(dmn->proTxHash);
        }

        LOCK2(cs_main, g_cs_orphans);

        bool fMissingInputs = false;
        CValidationState state;

        EraseObjectRequest(pfrom->GetId(), inv);

        if (!AlreadyHave(inv) && AcceptToMemoryPool(mempool, state, ptx, &fMissingInputs /* pfMissingInputs */,
                false /* bypass_limits */, 0 /* nAbsurdFee */)) {
            // Process custom txes, this changes AlreadyHave to "true"
            if (nInvType == MSG_DSTX) {
                LogPrint(BCLog::PRIVATESEND, "DSTX -- Masternode transaction accepted, txid=%s, peer=%d\n",
                         tx.GetHash().ToString(), pfrom->GetId());
                CPrivateSend::AddDSTX(dstx);
            }

            mempool.check(pcoinsTip.get());
            connman->RelayTransaction(tx);

            for (unsigned int i = 0; i < tx.vout.size(); i++) {
                auto it_by_prev = mapOrphanTransactionsByPrev.find(COutPoint(inv.hash, i));
                if (it_by_prev != mapOrphanTransactionsByPrev.end()) {
                    for (const auto& elem : it_by_prev->second) {
                        pfrom->orphan_work_set.insert(elem->first);
                    }
                }
            }

            pfrom->nLastTXTime = GetTime();

            LogPrint(BCLog::MEMPOOL, "AcceptToMemoryPool: peer=%d: accepted %s (poolsz %u txn, %u kB)\n",
                     pfrom->GetId(),
                     tx.GetHash().ToString(),
                     mempool.size(), mempool.DynamicMemoryUsage() / 1000);

            // Recursively process any orphan transactions that depended on this one
            ProcessOrphanTx(connman, pfrom->orphan_work_set);
        }
        else if (fMissingInputs)
        {
            bool fRejectedParents = false; // It may be the case that the orphans parents have all been rejected
            for (const CTxIn& txin : tx.vin) {
                if (recentRejects->contains(txin.prevout.hash)) {
                    fRejectedParents = true;
                    break;
                }
            }
            if (!fRejectedParents) {
                const auto current_time = GetTime<std::chrono::microseconds>();

                for (const CTxIn& txin : tx.vin) {
                    CInv _inv(MSG_TX, txin.prevout.hash);
                    pfrom->AddInventoryKnown(_inv);
                    if (!AlreadyHave(_inv)) RequestObject(State(pfrom->GetId()), _inv, current_time);
                    // We don't know if the previous tx was a regular or a mixing one, try both
                    CInv _inv2(MSG_DSTX, txin.prevout.hash);
                    pfrom->AddInventoryKnown(_inv2);
                    if (!AlreadyHave(_inv2)) RequestObject(State(pfrom->GetId()), _inv2, current_time);
                }
                AddOrphanTx(ptx, pfrom->GetId());

                // DoS prevention: do not allow mapOrphanTransactions to grow unbounded
                unsigned int nMaxOrphanTxSize = (unsigned int)std::max((int64_t)0, gArgs.GetArg("-maxorphantxsize", DEFAULT_MAX_ORPHAN_TRANSACTIONS_SIZE)) * 1000000;
                unsigned int nEvicted = LimitOrphanTxSize(nMaxOrphanTxSize);
                if (nEvicted > 0) {
                    LogPrint(BCLog::MEMPOOL, "mapOrphan overflow, removed %u tx\n", nEvicted);
                }
            } else {
                LogPrint(BCLog::MEMPOOL, "not keeping orphan with rejected parents %s\n",tx.GetHash().ToString());
                // We will continue to reject this tx since it has rejected
                // parents so avoid re-requesting it from other peers.
                recentRejects->insert(tx.GetHash());
            }
        } else {
            if (!state.CorruptionPossible()) {
                assert(recentRejects);
                recentRejects->insert(tx.GetHash());
                if (RecursiveDynamicUsage(*ptx) < 100000) {
                    AddToCompactExtraTransactions(ptx);
                }
            }

            if (pfrom->fWhitelisted && gArgs.GetBoolArg("-whitelistforcerelay", DEFAULT_WHITELISTFORCERELAY)) {
                // Always relay transactions received from whitelisted peers, even
                // if they were already in the mempool or rejected from it due
                // to policy, allowing the node to function as a gateway for
                // nodes hidden behind it.
                //
                // Never relay transactions that we would assign a non-zero DoS
                // score for, as we expect peers to do the same with us in that
                // case.
                int nDoS = 0;
                if (!state.IsInvalid(nDoS) || nDoS == 0) {
                    LogPrintf("Force relaying tx %s from whitelisted peer=%d\n", tx.GetHash().ToString(), pfrom->GetId());
                    connman->RelayTransaction(tx);
                } else {
                    LogPrintf("Not relaying invalid transaction %s from whitelisted peer=%d (%s)\n", tx.GetHash().ToString(), pfrom->GetId(), FormatStateMessage(state));
                }
            }
        }

        int nDoS = 0;
        if (state.IsInvalid(nDoS))
        {
            LogPrint(BCLog::MEMPOOLREJ, "%s from peer=%d was not accepted: %s\n", tx.GetHash().ToString(),
                pfrom->GetId(),
                FormatStateMessage(state));
            if (g_enable_bip61 && state.GetRejectCode() > 0 && state.GetRejectCode() < REJECT_INTERNAL) { // Never send AcceptToMemoryPool's internal codes over P2P
                connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::REJECT, strCommand, (unsigned char)state.GetRejectCode(),
                                   state.GetRejectReason().substr(0, MAX_REJECT_MESSAGE_LENGTH), inv.hash));
            }
            if (nDoS > 0) {
                Misbehaving(pfrom->GetId(), nDoS);
            }
        }
        return true;
    }

    if (strCommand == NetMsgType::CMPCTBLOCK && !fImporting && !fReindex) // Ignore blocks received while importing
    {
        CBlockHeaderAndShortTxIDs cmpctblock;
        vRecv >> cmpctblock;

        bool received_new_header = false;

        {
        LOCK(cs_main);

        if (mapBlockIndex.find(cmpctblock.header.hashPrevBlock) == mapBlockIndex.end()) {
            // Doesn't connect (or is genesis), instead of DoSing in AcceptBlockHeader, request deeper headers
            if (!IsInitialBlockDownload())
                connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::GETHEADERS, chainActive.GetLocator(pindexBestHeader), uint256()));
            return true;
        }

        if (mapBlockIndex.find(cmpctblock.header.GetHash()) == mapBlockIndex.end()) {
            received_new_header = true;
        }
        }

        const CBlockIndex *pindex = nullptr;
        CValidationState state;
        if (!ProcessNewBlockHeaders({cmpctblock.header}, state, chainparams, &pindex)) {
            int nDoS;
            if (state.IsInvalid(nDoS)) {
                if (nDoS > 0) {
                    LOCK(cs_main);
                    Misbehaving(pfrom->GetId(), nDoS, strprintf("Peer %d sent us invalid header via cmpctblock", pfrom->GetId()));
                } else {
                    LogPrint(BCLog::NET, "Peer %d sent us invalid header via cmpctblock\n", pfrom->GetId());
                }
                return true;
            }
        }

        // When we succeed in decoding a block's txids from a cmpctblock
        // message we typically jump to the BLOCKTXN handling code, with a
        // dummy (empty) BLOCKTXN message, to re-use the logic there in
        // completing processing of the putative block (without cs_main).
        bool fProcessBLOCKTXN = false;
        CDataStream blockTxnMsg(SER_NETWORK, PROTOCOL_VERSION);

        // If we end up treating this as a plain headers message, call that as well
        // without cs_main.
        bool fRevertToHeaderProcessing = false;

        // Keep a CBlock for "optimistic" compactblock reconstructions (see
        // below)
        std::shared_ptr<CBlock> pblock = std::make_shared<CBlock>();
        bool fBlockReconstructed = false;

        {
        LOCK2(cs_main, g_cs_orphans);
        // If AcceptBlockHeader returned true, it set pindex
        assert(pindex);
        UpdateBlockAvailability(pfrom->GetId(), pindex->GetBlockHash());

        CNodeState *nodestate = State(pfrom->GetId());

        // If this was a new header with more work than our tip, update the
        // peer's last block announcement time
        if (received_new_header && pindex->nChainWork > chainActive.Tip()->nChainWork) {
            nodestate->m_last_block_announcement = GetTime();
        }

        std::map<uint256, std::pair<NodeId, std::list<QueuedBlock>::iterator> >::iterator blockInFlightIt = mapBlocksInFlight.find(pindex->GetBlockHash());
        bool fAlreadyInFlight = blockInFlightIt != mapBlocksInFlight.end();

        if (pindex->nStatus & BLOCK_HAVE_DATA) // Nothing to do here
            return true;

        if (pindex->nChainWork <= chainActive.Tip()->nChainWork || // We know something better
                pindex->nTx != 0) { // We had this block at some point, but pruned it
            if (fAlreadyInFlight) {
                // We requested this block for some reason, but our mempool will probably be useless
                // so we just grab the block via normal getdata
                std::vector<CInv> vInv(1);
                vInv[0] = CInv(MSG_BLOCK, cmpctblock.header.GetHash());
                connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::GETDATA, vInv));
            }
            return true;
        }

        // If we're not close to tip yet, give up and let parallel block fetch work its magic
        if (!fAlreadyInFlight && !CanDirectFetch(chainparams.GetConsensus()))
            return true;

        // We want to be a bit conservative just to be extra careful about DoS
        // possibilities in compact block processing...
        if (pindex->nHeight <= chainActive.Height() + 2) {
            if ((!fAlreadyInFlight && nodestate->nBlocksInFlight < MAX_BLOCKS_IN_TRANSIT_PER_PEER) ||
                 (fAlreadyInFlight && blockInFlightIt->second.first == pfrom->GetId())) {
                std::list<QueuedBlock>::iterator *queuedBlockIt = nullptr;
                if (!MarkBlockAsInFlight(pfrom->GetId(), pindex->GetBlockHash(), pindex, &queuedBlockIt)) {
                    if (!(*queuedBlockIt)->partialBlock)
                        (*queuedBlockIt)->partialBlock.reset(new PartiallyDownloadedBlock(&mempool));
                    else {
                        // The block was already in flight using compact blocks from the same peer
                        LogPrint(BCLog::NET, "Peer sent us compact block we were already syncing!\n");
                        return true;
                    }
                }

                PartiallyDownloadedBlock& partialBlock = *(*queuedBlockIt)->partialBlock;
                ReadStatus status = partialBlock.InitData(cmpctblock, vExtraTxnForCompact);
                if (status == READ_STATUS_INVALID) {
                    MarkBlockAsReceived(pindex->GetBlockHash()); // Reset in-flight state in case of whitelist
                    Misbehaving(pfrom->GetId(), 100, strprintf("Peer %d sent us invalid compact block", pfrom->GetId()));
                    return true;
                } else if (status == READ_STATUS_FAILED) {
                    // Duplicate txindexes, the block is now in-flight, so just request it
                    std::vector<CInv> vInv(1);
                    vInv[0] = CInv(MSG_BLOCK, cmpctblock.header.GetHash());
                    connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::GETDATA, vInv));
                    return true;
                }

                BlockTransactionsRequest req;
                for (size_t i = 0; i < cmpctblock.BlockTxCount(); i++) {
                    if (!partialBlock.IsTxAvailable(i))
                        req.indexes.push_back(i);
                }
                if (req.indexes.empty()) {
                    // Dirty hack to jump to BLOCKTXN code (TODO: move message handling into their own functions)
                    BlockTransactions txn;
                    txn.blockhash = cmpctblock.header.GetHash();
                    blockTxnMsg << txn;
                    fProcessBLOCKTXN = true;
                } else {
                    req.blockhash = pindex->GetBlockHash();
                    connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::GETBLOCKTXN, req));
                }
            } else {
                // This block is either already in flight from a different
                // peer, or this peer has too many blocks outstanding to
                // download from.
                // Optimistically try to reconstruct anyway since we might be
                // able to without any round trips.
                PartiallyDownloadedBlock tempBlock(&mempool);
                ReadStatus status = tempBlock.InitData(cmpctblock, vExtraTxnForCompact);
                if (status != READ_STATUS_OK) {
                    // TODO: don't ignore failures
                    return true;
                }
                std::vector<CTransactionRef> dummy;
                status = tempBlock.FillBlock(*pblock, dummy);
                if (status == READ_STATUS_OK) {
                    fBlockReconstructed = true;
                }
            }
        } else {
            if (fAlreadyInFlight) {
                // We requested this block, but its far into the future, so our
                // mempool will probably be useless - request the block normally
                std::vector<CInv> vInv(1);
                vInv[0] = CInv(MSG_BLOCK, cmpctblock.header.GetHash());
                connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::GETDATA, vInv));
                return true;
            } else {
                // If this was an announce-cmpctblock, we want the same treatment as a header message
                fRevertToHeaderProcessing = true;
            }
        }
        } // cs_main

        if (fProcessBLOCKTXN)
            return ProcessMessage(pfrom, NetMsgType::BLOCKTXN, blockTxnMsg, nTimeReceived, chainparams, connman, interruptMsgProc);

        if (fRevertToHeaderProcessing) {
            // Headers received from HB compact block peers are permitted to be
            // relayed before full validation (see BIP 152), so we don't want to disconnect
            // the peer if the header turns out to be for an invalid block.
            // Note that if a peer tries to build on an invalid chain, that
            // will be detected and the peer will be banned.
            return ProcessHeadersMessage(pfrom, connman, {cmpctblock.header}, chainparams, /*punish_duplicate_invalid=*/false);
        }

        if (fBlockReconstructed) {
            // If we got here, we were able to optimistically reconstruct a
            // block that is in flight from some other peer.
            {
                LOCK(cs_main);
                mapBlockSource.emplace(pblock->GetHash(), std::make_pair(pfrom->GetId(), false));
            }
            bool fNewBlock = false;
            // Setting fForceProcessing to true means that we bypass some of
            // our anti-DoS protections in AcceptBlock, which filters
            // unrequested blocks that might be trying to waste our resources
            // (eg disk space). Because we only try to reconstruct blocks when
            // we're close to caught up (via the CanDirectFetch() requirement
            // above, combined with the behavior of not requesting blocks until
            // we have a chain with at least nMinimumChainWork), and we ignore
            // compact blocks with less work than our tip, it is safe to treat
            // reconstructed compact blocks as having been requested.
            ProcessNewBlock(chainparams, pblock, /*fForceProcessing=*/true, &fNewBlock);
            if (fNewBlock) {
                pfrom->nLastBlockTime = GetTime();
            } else {
                LOCK(cs_main);
                mapBlockSource.erase(pblock->GetHash());
            }
            LOCK(cs_main); // hold cs_main for CBlockIndex::IsValid()
            if (pindex->IsValid(BLOCK_VALID_TRANSACTIONS)) {
                // Clear download state for this block, which is in
                // process from some other peer.  We do this after calling
                // ProcessNewBlock so that a malleated cmpctblock announcement
                // can't be used to interfere with block relay.
                MarkBlockAsReceived(pblock->GetHash());
            }
        }
        return true;
    }

    if (strCommand == NetMsgType::BLOCKTXN && !fImporting && !fReindex) // Ignore blocks received while importing
    {
        BlockTransactions resp;
        vRecv >> resp;

        std::shared_ptr<CBlock> pblock = std::make_shared<CBlock>();
        bool fBlockRead = false;
        {
            LOCK(cs_main);

            std::map<uint256, std::pair<NodeId, std::list<QueuedBlock>::iterator> >::iterator it = mapBlocksInFlight.find(resp.blockhash);
            if (it == mapBlocksInFlight.end() || !it->second.second->partialBlock ||
                    it->second.first != pfrom->GetId()) {
                LogPrint(BCLog::NET, "Peer %d sent us block transactions for block we weren't expecting\n", pfrom->GetId());
                return true;
            }

            PartiallyDownloadedBlock& partialBlock = *it->second.second->partialBlock;
            ReadStatus status = partialBlock.FillBlock(*pblock, resp.txn);
            if (status == READ_STATUS_INVALID) {
                MarkBlockAsReceived(resp.blockhash); // Reset in-flight state in case of whitelist
                Misbehaving(pfrom->GetId(), 100, strprintf("Peer %d sent us invalid compact block/non-matching block transactions", pfrom->GetId()));
                return true;
            } else if (status == READ_STATUS_FAILED) {
                // Might have collided, fall back to getdata now :(
                std::vector<CInv> invs;
                invs.push_back(CInv(MSG_BLOCK, resp.blockhash));
                connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::GETDATA, invs));
            } else {
                // Block is either okay, or possibly we received
                // READ_STATUS_CHECKBLOCK_FAILED.
                // Note that CheckBlock can only fail for one of a few reasons:
                // 1. bad-proof-of-work (impossible here, because we've already
                //    accepted the header)
                // 2. merkleroot doesn't match the transactions given (already
                //    caught in FillBlock with READ_STATUS_FAILED, so
                //    impossible here)
                // 3. the block is otherwise invalid (eg invalid coinbase,
                //    block is too big, too many legacy sigops, etc).
                // So if CheckBlock failed, #3 is the only possibility.
                // Under BIP 152, we don't DoS-ban unless proof of work is
                // invalid (we don't require all the stateless checks to have
                // been run).  This is handled below, so just treat this as
                // though the block was successfully read, and rely on the
                // handling in ProcessNewBlock to ensure the block index is
                // updated, reject messages go out, etc.
                MarkBlockAsReceived(resp.blockhash); // it is now an empty pointer
                fBlockRead = true;
                // mapBlockSource is only used for sending reject messages and DoS scores,
                // so the race between here and cs_main in ProcessNewBlock is fine.
                // BIP 152 permits peers to relay compact blocks after validating
                // the header only; we should not punish peers if the block turns
                // out to be invalid.
                mapBlockSource.emplace(resp.blockhash, std::make_pair(pfrom->GetId(), false));
            }
        } // Don't hold cs_main when we call into ProcessNewBlock
        if (fBlockRead) {
            bool fNewBlock = false;
            // Since we requested this block (it was in mapBlocksInFlight), force it to be processed,
            // even if it would not be a candidate for new tip (missing previous block, chain not long enough, etc)
            // This bypasses some anti-DoS logic in AcceptBlock (eg to prevent
            // disk-space attacks), but this should be safe due to the
            // protections in the compact block handler -- see related comment
            // in compact block optimistic reconstruction handling.
            ProcessNewBlock(chainparams, pblock, /*fForceProcessing=*/true, &fNewBlock);
            if (fNewBlock) {
                pfrom->nLastBlockTime = GetTime();
            } else {
                LOCK(cs_main);
                mapBlockSource.erase(pblock->GetHash());
            }
        }
        return true;
    }

    if (strCommand == NetMsgType::HEADERS && !fImporting && !fReindex) // Ignore headers received while importing
    {
        std::vector<CBlockHeader> headers;

        // Bypass the normal CBlock deserialization, as we don't want to risk deserializing 2000 full blocks.
        unsigned int nCount = ReadCompactSize(vRecv);
        if (nCount > MAX_HEADERS_RESULTS) {
            LOCK(cs_main);
            Misbehaving(pfrom->GetId(), 20, strprintf("headers message size = %u", nCount));
            return false;
        }
        headers.resize(nCount);
        for (unsigned int n = 0; n < nCount; n++) {
            vRecv >> headers[n];
            ReadCompactSize(vRecv); // ignore tx count; assume it is 0.
        }

        // Headers received via a HEADERS message should be valid, and reflect
        // the chain the peer is on. If we receive a known-invalid header,
        // disconnect the peer if it is using one of our outbound connection
        // slots.
        bool should_punish = !pfrom->fInbound && !pfrom->m_manual_connection;
        return ProcessHeadersMessage(pfrom, connman, headers, chainparams, should_punish);
    }

    if (strCommand == NetMsgType::BLOCK && !fImporting && !fReindex) // Ignore blocks received while importing
    {
        std::shared_ptr<CBlock> pblock = std::make_shared<CBlock>();
        vRecv >> *pblock;

        LogPrint(BCLog::NET, "received block %s peer=%d\n", pblock->GetHash().ToString(), pfrom->GetId());

        bool forceProcessing = false;
        const uint256 hash(pblock->GetHash());
        {
            LOCK(cs_main);
            // Also always process if we requested the block explicitly, as we may
            // need it even though it is not a candidate for a new best tip.
            forceProcessing |= MarkBlockAsReceived(hash);
            // mapBlockSource is only used for sending reject messages and DoS scores,
            // so the race between here and cs_main in ProcessNewBlock is fine.
            mapBlockSource.emplace(hash, std::make_pair(pfrom->GetId(), true));
        }
        bool fNewBlock = false;
        ProcessNewBlock(chainparams, pblock, forceProcessing, &fNewBlock);
        if (fNewBlock) {
            pfrom->nLastBlockTime = GetTime();
        } else {
            LOCK(cs_main);
            mapBlockSource.erase(pblock->GetHash());
        }
        return true;
    }

    if (strCommand == NetMsgType::GETADDR) {
        // This asymmetric behavior for inbound and outbound connections was introduced
        // to prevent a fingerprinting attack: an attacker can send specific fake addresses
        // to users' AddrMan and later request them by sending getaddr messages.
        // Making nodes which are behind NAT and can only make outgoing connections ignore
        // the getaddr message mitigates the attack.
        if (!pfrom->fInbound) {
            LogPrint(BCLog::NET, "Ignoring \"getaddr\" from outbound connection. peer=%d\n", pfrom->GetId());
            return true;
        }

        // Only send one GetAddr response per connection to reduce resource waste
        //  and discourage addr stamping of INV announcements.
        if (pfrom->fSentAddr) {
            LogPrint(BCLog::NET, "Ignoring repeated \"getaddr\". peer=%d\n", pfrom->GetId());
            return true;
        }
        pfrom->fSentAddr = true;

        pfrom->vAddrToSend.clear();
        std::vector<CAddress> vAddr = connman->GetAddresses();
        FastRandomContext insecure_rand;
        for (const CAddress &addr : vAddr)
            pfrom->PushAddress(addr, insecure_rand);
        return true;
    }

    if (strCommand == NetMsgType::MEMPOOL) {
        if (!(pfrom->GetLocalServices() & NODE_BLOOM) && !pfrom->fWhitelisted)
        {
            LogPrint(BCLog::NET, "mempool request with bloom filters disabled, disconnect peer=%d\n", pfrom->GetId());
            pfrom->fDisconnect = true;
            return true;
        }

        if (connman->OutboundTargetReached(false) && !pfrom->fWhitelisted)
        {
            LogPrint(BCLog::NET, "mempool request with bandwidth limit reached, disconnect peer=%d\n", pfrom->GetId());
            pfrom->fDisconnect = true;
            return true;
        }

        LOCK(pfrom->cs_inventory);
        pfrom->fSendMempool = true;
        return true;
    }

    if (strCommand == NetMsgType::PING) {
        if (pfrom->nVersion > BIP0031_VERSION)
        {
            uint64_t nonce = 0;
            vRecv >> nonce;
            // Echo the message back with the nonce. This allows for two useful features:
            //
            // 1) A remote node can quickly check if the connection is operational
            // 2) Remote nodes can measure the latency of the network thread. If this node
            //    is overloaded it won't respond to pings quickly and the remote node can
            //    avoid sending us more work, like chain download requests.
            //
            // The nonce stops the remote getting confused between different pings: without
            // it, if the remote node sends a ping once per second and this node takes 5
            // seconds to respond to each, the 5th ping the remote sends would appear to
            // return very quickly.
            connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::PONG, nonce));
        }
        return true;
    }

    if (strCommand == NetMsgType::PONG) {
        int64_t pingUsecEnd = nTimeReceived;
        uint64_t nonce = 0;
        size_t nAvail = vRecv.in_avail();
        bool bPingFinished = false;
        std::string sProblem;

        if (nAvail >= sizeof(nonce)) {
            vRecv >> nonce;

            // Only process pong message if there is an outstanding ping (old ping without nonce should never pong)
            if (pfrom->nPingNonceSent != 0) {
                if (nonce == pfrom->nPingNonceSent) {
                    // Matching pong received, this ping is no longer outstanding
                    bPingFinished = true;
                    int64_t pingUsecTime = pingUsecEnd - pfrom->nPingUsecStart;
                    if (pingUsecTime > 0) {
                        // Successful ping time measurement, replace previous
                        pfrom->nPingUsecTime = pingUsecTime;
                        pfrom->nMinPingUsecTime = std::min(pfrom->nMinPingUsecTime.load(), pingUsecTime);
                    } else {
                        // This should never happen
                        sProblem = "Timing mishap";
                    }
                } else {
                    // Nonce mismatches are normal when pings are overlapping
                    sProblem = "Nonce mismatch";
                    if (nonce == 0) {
                        // This is most likely a bug in another implementation somewhere; cancel this ping
                        bPingFinished = true;
                        sProblem = "Nonce zero";
                    }
                }
            } else {
                sProblem = "Unsolicited pong without ping";
            }
        } else {
            // This is most likely a bug in another implementation somewhere; cancel this ping
            bPingFinished = true;
            sProblem = "Short payload";
        }

        if (!(sProblem.empty())) {
            LogPrint(BCLog::NET, "pong peer=%d: %s, %x expected, %x received, %u bytes\n",
                pfrom->GetId(),
                sProblem,
                pfrom->nPingNonceSent,
                nonce,
                nAvail);
        }
        if (bPingFinished) {
            pfrom->nPingNonceSent = 0;
        }
        return true;
    }

    if (strCommand == NetMsgType::FILTERLOAD) {
        CBloomFilter filter;
        vRecv >> filter;

        if (!filter.IsWithinSizeConstraints())
        {
            // There is no excuse for sending a too-large filter
            LOCK(cs_main);
            Misbehaving(pfrom->GetId(), 100);
        }
        else
        {
            LOCK(pfrom->cs_filter);
            pfrom->pfilter.reset(new CBloomFilter(filter));
            pfrom->pfilter->UpdateEmptyFull();
            pfrom->fRelayTxes = true;
        }
        return true;
    }

    if (strCommand == NetMsgType::FILTERADD) {
        std::vector<unsigned char> vData;
        vRecv >> vData;

        // Nodes must NEVER send a data item > 520 bytes (the max size for a script data object,
        // and thus, the maximum size any matched object can have) in a filteradd message
        bool bad = false;
        if (vData.size() > MAX_SCRIPT_ELEMENT_SIZE) {
            bad = true;
        } else {
            LOCK(pfrom->cs_filter);
            if (pfrom->pfilter) {
                pfrom->pfilter->insert(vData);
            } else {
                bad = true;
            }
        }
        if (bad) {
            LOCK(cs_main);
            Misbehaving(pfrom->GetId(), 100);
        }
        return true;
    }

    if (strCommand == NetMsgType::FILTERCLEAR) {
        LOCK(pfrom->cs_filter);
        if (pfrom->GetLocalServices() & NODE_BLOOM) {
            pfrom->pfilter.reset(new CBloomFilter());
        }
        pfrom->fRelayTxes = true;
        return true;
    }


    if (strCommand == NetMsgType::GETMNLISTDIFF) {
        CGetSimplifiedMNListDiff cmd;
        vRecv >> cmd;

        LOCK(cs_main);

        CSimplifiedMNListDiff mnListDiff;
        std::string strError;
        if (BuildSimplifiedMNListDiff(cmd.baseBlockHash, cmd.blockHash, mnListDiff, strError)) {
            connman->PushMessage(pfrom, msgMaker.Make(NetMsgType::MNLISTDIFF, mnListDiff));
        } else {
            strError = strprintf("getmnlistdiff failed for baseBlockHash=%s, blockHash=%s. error=%s", cmd.baseBlockHash.ToString(), cmd.blockHash.ToString(), strError);
            Misbehaving(pfrom->GetId(), 1, strError);
        }
        return true;
    }


    if (strCommand == NetMsgType::MNLISTDIFF) {
        // we have never requested this
        LOCK(cs_main);
        Misbehaving(pfrom->GetId(), 100, strprintf("received not-requested mnlistdiff. peer=%d", pfrom->GetId()));
        return true;
    }


    if (strCommand == NetMsgType::NOTFOUND) {
        // Remove the NOTFOUND transactions from the peer
        LOCK(cs_main);
        CNodeState *state = State(pfrom->GetId());
        std::vector<CInv> vInv;
        vRecv >> vInv;
        if (vInv.size() <= MAX_PEER_OBJECT_IN_FLIGHT + MAX_BLOCKS_IN_TRANSIT_PER_PEER) {
            for (CInv &inv : vInv) {
                if (inv.IsKnownType()) {
                    // If we receive a NOTFOUND message for a txid we requested, erase
                    // it from our data structures for this peer.
                    auto in_flight_it = state->m_object_download.m_object_in_flight.find(inv);
                    if (in_flight_it == state->m_object_download.m_object_in_flight.end()) {
                        // Skip any further work if this is a spurious NOTFOUND
                        // message.
                        continue;
                    }
                    state->m_object_download.m_object_in_flight.erase(in_flight_it);
                    state->m_object_download.m_object_announced.erase(inv);
                }
            }
        }
        return true;
    }

    bool found = false;
    const std::vector<std::string> &allMessages = getAllNetMessageTypes();
    for (const std::string msg : allMessages) {
        if(msg == strCommand) {
            found = true;
            break;
        }
    }

    if (found)
    {
        //probably one the extensions
#ifdef ENABLE_WALLET
        privateSendClient.ProcessMessage(pfrom, strCommand, vRecv, *connman);
#endif // ENABLE_WALLET
        privateSendServer.ProcessMessage(pfrom, strCommand, vRecv, *connman);
        sporkManager.ProcessSpork(pfrom, strCommand, vRecv, *connman);
        masternodeSync.ProcessMessage(pfrom, strCommand, vRecv);
        governance.ProcessMessage(pfrom, strCommand, vRecv, *connman);
        CMNAuth::ProcessMessage(pfrom, strCommand, vRecv, *connman);
        llmq::quorumBlockProcessor->ProcessMessage(pfrom, strCommand, vRecv, *connman);
        llmq::quorumDKGSessionManager->ProcessMessage(pfrom, strCommand, vRecv, *connman);
        llmq::quorumSigSharesManager->ProcessMessage(pfrom, strCommand, vRecv, *connman);
        llmq::quorumSigningManager->ProcessMessage(pfrom, strCommand, vRecv, *connman);
        llmq::chainLocksHandler->ProcessMessage(pfrom, strCommand, vRecv, *connman);
        llmq::quorumInstantSendManager->ProcessMessage(pfrom, strCommand, vRecv, *connman);
        return true;
    }

    // Ignore unknown commands for extensibility
    LogPrint(BCLog::NET, "Unknown command \"%s\" from peer=%d\n", SanitizeString(strCommand), pfrom->GetId());

    return true;
}

static bool SendRejectsAndCheckIfBanned(CNode* pnode, CConnman* connman)
{
    AssertLockHeld(cs_main);
    CNodeState &state = *State(pnode->GetId());

    if (g_enable_bip61) {
        for (const CBlockReject& reject : state.rejects) {
            connman->PushMessage(pnode, CNetMsgMaker(INIT_PROTO_VERSION).Make(NetMsgType::REJECT, (std::string)NetMsgType::BLOCK, reject.chRejectCode, reject.strRejectReason, reject.hashBlock));
        }
    }
    state.rejects.clear();

    if (state.fShouldBan) {
        state.fShouldBan = false;
        if (pnode->fWhitelisted)
            LogPrintf("Warning: not punishing whitelisted peer %s!\n", pnode->GetLogString());
        else if (pnode->m_manual_connection)
            LogPrintf("Warning: not punishing manually-connected peer %s!\n", pnode->GetLogString());
        else {
            pnode->fDisconnect = true;
            if (pnode->addr.IsLocal())
                LogPrintf("Warning: not banning local peer %s!\n", pnode->GetLogString());
            else
            {
                connman->Ban(pnode->addr, BanReasonNodeMisbehaving);
            }
        }
        return true;
    }
    return false;
}

bool PeerLogicValidation::ProcessMessages(CNode* pfrom, std::atomic<bool>& interruptMsgProc)
{
    const CChainParams& chainparams = Params();
    //
    // Message format
    //  (4) message start
    //  (12) command
    //  (4) size
    //  (4) checksum
    //  (x) data
    //
    bool fMoreWork = false;

    if (!pfrom->vRecvGetData.empty())
        ProcessGetData(pfrom, chainparams, connman, interruptMsgProc);

    if (!pfrom->orphan_work_set.empty()) {
        LOCK2(cs_main, g_cs_orphans);
        ProcessOrphanTx(connman, pfrom->orphan_work_set);
    }

    if (pfrom->fDisconnect)
        return false;

    // this maintains the order of responses
    if (!pfrom->vRecvGetData.empty()) return true;
    if (!pfrom->orphan_work_set.empty()) return true;

    // Don't bother if send buffer is too full to respond anyway
    if (pfrom->fPauseSend)
        return false;

    std::list<CNetMessage> msgs;
    {
        LOCK(pfrom->cs_vProcessMsg);
        if (pfrom->vProcessMsg.empty())
            return false;
        // Just take one message
        msgs.splice(msgs.begin(), pfrom->vProcessMsg, pfrom->vProcessMsg.begin());
        pfrom->nProcessQueueSize -= msgs.front().vRecv.size() + CMessageHeader::HEADER_SIZE;
        pfrom->fPauseRecv = pfrom->nProcessQueueSize > connman->GetReceiveFloodSize();
        fMoreWork = !pfrom->vProcessMsg.empty();
    }
    CNetMessage& msg(msgs.front());

    msg.SetVersion(pfrom->GetRecvVersion());
    // Scan for message start
    if (memcmp(msg.hdr.pchMessageStart, chainparams.MessageStart(), CMessageHeader::MESSAGE_START_SIZE) != 0) {
        LogPrint(BCLog::NET, "PROCESSMESSAGE: INVALID MESSAGESTART %s peer=%d\n", SanitizeString(msg.hdr.GetCommand()), pfrom->GetId());
        pfrom->fDisconnect = true;
        return false;
    }

    // Read header
    CMessageHeader& hdr = msg.hdr;
    if (!hdr.IsValid(chainparams.MessageStart()))
    {
        LogPrint(BCLog::NET, "PROCESSMESSAGE: ERRORS IN HEADER %s peer=%d\n", SanitizeString(hdr.GetCommand()), pfrom->GetId());
        return fMoreWork;
    }
    std::string strCommand = hdr.GetCommand();

    // Message size
    unsigned int nMessageSize = hdr.nMessageSize;

    // Checksum
    CDataStream& vRecv = msg.vRecv;
    const uint256& hash = msg.GetMessageHash();
    if (memcmp(hash.begin(), hdr.pchChecksum, CMessageHeader::CHECKSUM_SIZE) != 0)
    {
        LogPrint(BCLog::NET, "%s(%s, %u bytes): CHECKSUM ERROR expected %s was %s\n", __func__,
           SanitizeString(strCommand), nMessageSize,
           HexStr(hash.begin(), hash.begin()+CMessageHeader::CHECKSUM_SIZE),
           HexStr(hdr.pchChecksum, hdr.pchChecksum+CMessageHeader::CHECKSUM_SIZE));
        return fMoreWork;
    }

    // Process message
    bool fRet = false;
    try
    {
        fRet = ProcessMessage(pfrom, strCommand, vRecv, msg.nTime, chainparams, connman, interruptMsgProc);
        if (interruptMsgProc)
            return false;
        if (!pfrom->vRecvGetData.empty())
            fMoreWork = true;
    }
    catch (const std::ios_base::failure& e)
    {
        if (g_enable_bip61) {
            connman->PushMessage(pfrom, CNetMsgMaker(INIT_PROTO_VERSION).Make(NetMsgType::REJECT, strCommand, REJECT_MALFORMED, std::string("error parsing message")));
        }
        if (strstr(e.what(), "end of data"))
        {
            // Allow exceptions from under-length message on vRecv
            LogPrint(BCLog::NET, "%s(%s, %u bytes): Exception '%s' caught, normally caused by a message being shorter than its stated length\n", __func__, SanitizeString(strCommand), nMessageSize, e.what());
        }
        else if (strstr(e.what(), "size too large"))
        {
            // Allow exceptions from over-long size
            LogPrint(BCLog::NET, "%s(%s, %u bytes): Exception '%s' caught\n", __func__, SanitizeString(strCommand), nMessageSize, e.what());
        }
        else if (strstr(e.what(), "non-canonical ReadCompactSize()"))
        {
            // Allow exceptions from non-canonical encoding
            LogPrint(BCLog::NET, "%s(%s, %u bytes): Exception '%s' caught\n", __func__, SanitizeString(strCommand), nMessageSize, e.what());
        }
        else
        {
            PrintExceptionContinue(std::current_exception(), "ProcessMessages()");
            }
        } catch (...) {
        PrintExceptionContinue(std::current_exception(), "ProcessMessages()");
    }

    if (!fRet) {
        LogPrint(BCLog::NET, "%s(%s, %u bytes) FAILED peer=%d\n", __func__, SanitizeString(strCommand), nMessageSize, pfrom->GetId());
    }

    LOCK(cs_main);
    SendRejectsAndCheckIfBanned(pfrom, connman);

    return fMoreWork;
}

void PeerLogicValidation::ConsiderEviction(CNode *pto, int64_t time_in_seconds)
{
    AssertLockHeld(cs_main);

    CNodeState &state = *State(pto->GetId());
    const CNetMsgMaker msgMaker(pto->GetSendVersion());

    if (!state.m_chain_sync.m_protect && IsOutboundDisconnectionCandidate(pto) && state.fSyncStarted) {
        // This is an outbound peer subject to disconnection if they don't
        // announce a block with as much work as the current tip within
        // CHAIN_SYNC_TIMEOUT + HEADERS_RESPONSE_TIME seconds (note: if
        // their chain has more work than ours, we should sync to it,
        // unless it's invalid, in which case we should find that out and
        // disconnect from them elsewhere).
        if (state.pindexBestKnownBlock != nullptr && state.pindexBestKnownBlock->nChainWork >= chainActive.Tip()->nChainWork) {
            if (state.m_chain_sync.m_timeout != 0) {
                state.m_chain_sync.m_timeout = 0;
                state.m_chain_sync.m_work_header = nullptr;
                state.m_chain_sync.m_sent_getheaders = false;
            }
        } else if (state.m_chain_sync.m_timeout == 0 || (state.m_chain_sync.m_work_header != nullptr && state.pindexBestKnownBlock != nullptr && state.pindexBestKnownBlock->nChainWork >= state.m_chain_sync.m_work_header->nChainWork)) {
            // Our best block known by this peer is behind our tip, and we're either noticing
            // that for the first time, OR this peer was able to catch up to some earlier point
            // where we checked against our tip.
            // Either way, set a new timeout based on current tip.
            state.m_chain_sync.m_timeout = time_in_seconds + CHAIN_SYNC_TIMEOUT;
            state.m_chain_sync.m_work_header = chainActive.Tip();
            state.m_chain_sync.m_sent_getheaders = false;
        } else if (state.m_chain_sync.m_timeout > 0 && time_in_seconds > state.m_chain_sync.m_timeout) {
            // No evidence yet that our peer has synced to a chain with work equal to that
            // of our tip, when we first detected it was behind. Send a single getheaders
            // message to give the peer a chance to update us.
            if (state.m_chain_sync.m_sent_getheaders) {
                // They've run out of time to catch up!
                LogPrintf("Disconnecting outbound peer %d for old chain, best known block = %s\n", pto->GetId(), state.pindexBestKnownBlock != nullptr ? state.pindexBestKnownBlock->GetBlockHash().ToString() : "<none>");
                pto->fDisconnect = true;
            } else {
                assert(state.m_chain_sync.m_work_header);
                LogPrint(BCLog::NET, "sending getheaders to outbound peer=%d to verify chain work (current best known block:%s, benchmark blockhash: %s)\n", pto->GetId(), state.pindexBestKnownBlock != nullptr ? state.pindexBestKnownBlock->GetBlockHash().ToString() : "<none>", state.m_chain_sync.m_work_header->GetBlockHash().ToString());
                connman->PushMessage(pto, msgMaker.Make(NetMsgType::GETHEADERS, chainActive.GetLocator(state.m_chain_sync.m_work_header->pprev), uint256()));
                state.m_chain_sync.m_sent_getheaders = true;
                constexpr int64_t HEADERS_RESPONSE_TIME = 120; // 2 minutes
                // Bump the timeout to allow a response, which could clear the timeout
                // (if the response shows the peer has synced), reset the timeout (if
                // the peer syncs to the required work but not to our tip), or result
                // in disconnect (if we advance to the timeout and pindexBestKnownBlock
                // has not sufficiently progressed)
                state.m_chain_sync.m_timeout = time_in_seconds + HEADERS_RESPONSE_TIME;
            }
        }
    }
}

void PeerLogicValidation::EvictExtraOutboundPeers(int64_t time_in_seconds)
{
    // Check whether we have too many outbound peers
    int extra_peers = connman->GetExtraOutboundCount();
    if (extra_peers > 0) {
        // If we have more outbound peers than we target, disconnect one.
        // Pick the outbound peer that least recently announced
        // us a new block, with ties broken by choosing the more recent
        // connection (higher node id)
        NodeId worst_peer = -1;
        int64_t oldest_block_announcement = std::numeric_limits<int64_t>::max();

        LOCK(cs_main);

        connman->ForEachNode([&](CNode* pnode) {
            // Don't disconnect masternodes just because they were slow in block announcement
            if (pnode->fMasternode) return;
            // Ignore non-outbound peers, or nodes marked for disconnect already
            if (!IsOutboundDisconnectionCandidate(pnode) || pnode->fDisconnect) return;
            CNodeState *state = State(pnode->GetId());
            if (state == nullptr) return; // shouldn't be possible, but just in case
            // Don't evict our protected peers
            if (state->m_chain_sync.m_protect) return;
            if (state->m_last_block_announcement < oldest_block_announcement || (state->m_last_block_announcement == oldest_block_announcement && pnode->GetId() > worst_peer)) {
                worst_peer = pnode->GetId();
                oldest_block_announcement = state->m_last_block_announcement;
            }
        });
        if (worst_peer != -1) {
            bool disconnected = connman->ForNode(worst_peer, [&](CNode *pnode) {
                // Only disconnect a peer that has been connected to us for
                // some reasonable fraction of our check-frequency, to give
                // it time for new information to have arrived.
                // Also don't disconnect any peer we're trying to download a
                // block from.
                CNodeState &state = *State(pnode->GetId());
                if (time_in_seconds - pnode->nTimeConnected > MINIMUM_CONNECT_TIME && state.nBlocksInFlight == 0) {
                    LogPrint(BCLog::NET, "disconnecting extra outbound peer=%d (last block announcement received at time %d)\n", pnode->GetId(), oldest_block_announcement);
                    pnode->fDisconnect = true;
                    return true;
                } else {
                    LogPrint(BCLog::NET, "keeping outbound peer=%d chosen for eviction (connect time: %d, blocks_in_flight: %d)\n", pnode->GetId(), pnode->nTimeConnected, state.nBlocksInFlight);
                    return false;
                }
            });
            if (disconnected) {
                // If we disconnected an extra peer, that means we successfully
                // connected to at least one peer after the last time we
                // detected a stale tip. Don't try any more extra peers until
                // we next detect a stale tip, to limit the load we put on the
                // network from these extra connections.
                connman->SetTryNewOutboundPeer(false);
            }
        }
    }
}

void PeerLogicValidation::CheckForStaleTipAndEvictPeers(const Consensus::Params &consensusParams)
{
    if (connman == nullptr) return;

    int64_t time_in_seconds = GetTime();

    EvictExtraOutboundPeers(time_in_seconds);

    if (time_in_seconds > m_stale_tip_check_time) {
        LOCK(cs_main);
        // Check whether our tip is stale, and if so, allow using an extra
        // outbound peer
        if (TipMayBeStale(consensusParams)) {
            LogPrintf("Potential stale tip detected, will try using extra outbound peer (last tip update: %d seconds ago)\n", time_in_seconds - g_last_tip_update);
            connman->SetTryNewOutboundPeer(true);
        } else if (connman->GetTryNewOutboundPeer()) {
            connman->SetTryNewOutboundPeer(false);
        }
        m_stale_tip_check_time = time_in_seconds + STALE_CHECK_INTERVAL;
    }
}

class CompareInvMempoolOrder
{
    CTxMemPool *mp;
public:
    explicit CompareInvMempoolOrder(CTxMemPool *_mempool)
    {
        mp = _mempool;
    }

    bool operator()(std::set<uint256>::iterator a, std::set<uint256>::iterator b)
    {
        /* As std::make_heap produces a max-heap, we want the entries with the
         * fewest ancestors/highest fee to sort later. */
        return mp->CompareDepthAndScore(*b, *a);
    }
};

bool PeerLogicValidation::SendMessages(CNode* pto, std::atomic<bool>& interruptMsgProc)
{
    const Consensus::Params& consensusParams = Params().GetConsensus();
    {
        // Don't send anything until the version handshake is complete
        if (!pto->fSuccessfullyConnected || pto->fDisconnect)
            return true;

        // If we get here, the outgoing message serialization version is set and can't change.
        const CNetMsgMaker msgMaker(pto->GetSendVersion());

        //
        // Message: ping
        //
        bool pingSend = false;
        if (pto->fPingQueued) {
            // RPC ping request by user
            pingSend = true;
        }
        if (pto->nPingNonceSent == 0 && pto->nPingUsecStart + PING_INTERVAL * 1000000 < GetTimeMicros()) {
            // Ping automatically sent as a latency probe & keepalive.
            pingSend = true;
        }
        if (pingSend) {
            uint64_t nonce = 0;
            while (nonce == 0) {
                GetRandBytes((unsigned char*)&nonce, sizeof(nonce));
            }
            pto->fPingQueued = false;
            pto->nPingUsecStart = GetTimeMicros();
            if (pto->nVersion > BIP0031_VERSION) {
                pto->nPingNonceSent = nonce;
                connman->PushMessage(pto, msgMaker.Make(NetMsgType::PING, nonce));
            } else {
                // Peer is too old to support ping command with nonce, pong will never arrive.
                pto->nPingNonceSent = 0;
                connman->PushMessage(pto, msgMaker.Make(NetMsgType::PING));
            }
        }

        TRY_LOCK(cs_main, lockMain); // Acquire cs_main for IsInitialBlockDownload() and CNodeState()
        if (!lockMain)
            return true;

        if (SendRejectsAndCheckIfBanned(pto, connman))
            return true;
        CNodeState &state = *State(pto->GetId());

        // Address refresh broadcast
        int64_t nNow = GetTimeMicros();
        auto current_time = GetTime<std::chrono::microseconds>();

        if (!IsInitialBlockDownload() && pto->nNextLocalAddrSend < nNow) {
            AdvertiseLocal(pto);
            pto->nNextLocalAddrSend = PoissonNextSend(nNow, AVG_LOCAL_ADDRESS_BROADCAST_INTERVAL);
        }

        //
        // Message: addr
        //
        if (pto->nNextAddrSend < nNow) {
            pto->nNextAddrSend = PoissonNextSend(nNow, AVG_ADDRESS_BROADCAST_INTERVAL);
            std::vector<CAddress> vAddr;
            vAddr.reserve(pto->vAddrToSend.size());
            for (const CAddress& addr : pto->vAddrToSend)
            {
                if (!pto->addrKnown.contains(addr.GetKey()))
                {
                    pto->addrKnown.insert(addr.GetKey());
                    vAddr.push_back(addr);
                    // receiver rejects addr messages larger than 1000
                    if (vAddr.size() >= 1000)
                    {
                        connman->PushMessage(pto, msgMaker.Make(NetMsgType::ADDR, vAddr));
                        vAddr.clear();
                    }
                }
            }
            pto->vAddrToSend.clear();
            if (!vAddr.empty())
                connman->PushMessage(pto, msgMaker.Make(NetMsgType::ADDR, vAddr));
            // we only send the big addr message once
            if (pto->vAddrToSend.capacity() > 40)
                pto->vAddrToSend.shrink_to_fit();
        }

        // Start block sync
        if (pindexBestHeader == nullptr)
            pindexBestHeader = chainActive.Tip();
        bool fFetch = state.fPreferredDownload || (nPreferredDownload == 0 && !pto->fClient && !pto->fOneShot); // Download if this is a nice peer, or we have no nice peers and this one might do.
        if (!state.fSyncStarted && !pto->fClient && !fImporting && !fReindex && !pto->fMasternode) {
            // Only actively request headers from a single peer, unless we're close to end of initial download.
            if ((nSyncStarted == 0 && fFetch) || pindexBestHeader->GetBlockTime() > GetAdjustedTime() - nMaxTipAge) {
                state.fSyncStarted = true;
                state.nHeadersSyncTimeout = GetTimeMicros() + HEADERS_DOWNLOAD_TIMEOUT_BASE + HEADERS_DOWNLOAD_TIMEOUT_PER_HEADER * (GetAdjustedTime() - pindexBestHeader->GetBlockTime())/(consensusParams.nPowTargetSpacing);
                nSyncStarted++;
                const CBlockIndex *pindexStart = pindexBestHeader;
                /* If possible, start at the block preceding the currently
                   best known header.  This ensures that we always get a
                   non-empty list of headers back as long as the peer
                   is up-to-date.  With a non-empty response, we can initialise
                   the peer's known best block.  This wouldn't be possible
                   if we requested starting at pindexBestHeader and
                   got back an empty response.  */
                if (pindexStart->pprev)
                    pindexStart = pindexStart->pprev;
                LogPrint(BCLog::NET, "initial getheaders (%d) to peer=%d (startheight:%d)\n", pindexStart->nHeight, pto->GetId(), pto->nStartingHeight);
                connman->PushMessage(pto, msgMaker.Make(NetMsgType::GETHEADERS, chainActive.GetLocator(pindexStart), uint256()));
            }
        }

        // Resend wallet transactions that haven't gotten in a block yet
        // Except during reindex, importing and IBD, when old wallet
        // transactions become unconfirmed and spams other nodes.
        if (!fReindex && !fImporting && !IsInitialBlockDownload())
        {
            static int64_t nLastBroadcastTime = 0;
            // HACK: Call this only once every few seconds. SendMessages is called once per peer, which makes this signal very expensive
            // The proper solution would be to move this out of here, but this is not worth the effort right now as bitcoin#15632 will later do this.
            // Luckily, the Broadcast signal is not used for anything else then CWallet::ResendWalletTransactionsBefore.
            if (nNow - nLastBroadcastTime >= 5000000) {
                GetMainSignals().Broadcast(nTimeBestReceived, connman);
                nLastBroadcastTime = nNow;
            }
        }

        //
        // Try sending block announcements via headers
        //
        if (!pto->fMasternode) {
            // If we have less than MAX_BLOCKS_TO_ANNOUNCE in our
            // list of block hashes we're relaying, and our peer wants
            // headers announcements, then find the first header
            // not yet known to our peer but would connect, and send.
            // If no header would connect, or if we have too many
            // blocks, or if the peer doesn't want headers, just
            // add all to the inv queue.
            LOCK(pto->cs_inventory);
            std::vector<CBlock> vHeaders;
            bool fRevertToInv = ((!state.fPreferHeaders &&
                                 (!state.fPreferHeaderAndIDs || pto->vBlockHashesToAnnounce.size() > 1)) ||
                                 pto->vBlockHashesToAnnounce.size() > MAX_BLOCKS_TO_ANNOUNCE);
            const CBlockIndex *pBestIndex = nullptr; // last header queued for delivery
            ProcessBlockAvailability(pto->GetId()); // ensure pindexBestKnownBlock is up-to-date

            if (!fRevertToInv) {
                bool fFoundStartingHeader = false;
                // Try to find first header that our peer doesn't have, and
                // then send all headers past that one.  If we come across any
                // headers that aren't on chainActive, give up.
                for (const uint256 &hash : pto->vBlockHashesToAnnounce) {
                    BlockMap::iterator mi = mapBlockIndex.find(hash);
                    assert(mi != mapBlockIndex.end());
                    const CBlockIndex *pindex = mi->second;
                    if (chainActive[pindex->nHeight] != pindex) {
                        // Bail out if we reorged away from this block
                        fRevertToInv = true;
                        break;
                    }
                    if (pBestIndex != nullptr && pindex->pprev != pBestIndex) {
                        // This means that the list of blocks to announce don't
                        // connect to each other.
                        // This shouldn't really be possible to hit during
                        // regular operation (because reorgs should take us to
                        // a chain that has some block not on the prior chain,
                        // which should be caught by the prior check), but one
                        // way this could happen is by using invalidateblock /
                        // reconsiderblock repeatedly on the tip, causing it to
                        // be added multiple times to vBlockHashesToAnnounce.
                        // Robustly deal with this rare situation by reverting
                        // to an inv.
                        fRevertToInv = true;
                        break;
                    }
                    pBestIndex = pindex;
                    bool isPrevDevnetGenesisBlock = false;
                    if (!consensusParams.hashDevnetGenesisBlock.IsNull() &&
                        pindex->pprev != nullptr &&
                        pindex->pprev->GetBlockHash() == consensusParams.hashDevnetGenesisBlock) {
                        // even though the devnet genesis block was never transferred through the wire and thus not
                        // appear anywhere in the node state where we track what other nodes have or not have, we can
                        // assume that the other node already knows the devnet genesis block
                        isPrevDevnetGenesisBlock = true;
                    }
                    if (fFoundStartingHeader) {
                        // add this to the headers message
                        vHeaders.push_back(pindex->GetBlockHeader());
                    } else if (PeerHasHeader(&state, pindex)) {
                        continue; // keep looking for the first new block
                    } else if (pindex->pprev == nullptr || PeerHasHeader(&state, pindex->pprev) || isPrevDevnetGenesisBlock) {
                        // Peer doesn't have this header but they do have the prior one.
                        // Start sending headers.
                        fFoundStartingHeader = true;
                        vHeaders.push_back(pindex->GetBlockHeader());
                    } else {
                        // Peer doesn't have this header or the prior one -- nothing will
                        // connect, so bail out.
                        fRevertToInv = true;
                        break;
                    }
                }
            }
            if (!fRevertToInv && !vHeaders.empty()) {
                if (vHeaders.size() == 1 && state.fPreferHeaderAndIDs) {
                    // We only send up to 1 block as header-and-ids, as otherwise
                    // probably means we're doing an initial-ish-sync or they're slow
                    LogPrint(BCLog::NET, "%s sending header-and-ids %s to peer=%d\n", __func__,
                            vHeaders.front().GetHash().ToString(), pto->GetId());

                    bool fGotBlockFromCache = false;
                    {
                        LOCK(cs_most_recent_block);
                        if (most_recent_block_hash == pBestIndex->GetBlockHash()) {
                            connman->PushMessage(pto, msgMaker.Make(NetMsgType::CMPCTBLOCK, *most_recent_compact_block));
                            fGotBlockFromCache = true;
                        }
                    }
                    if (!fGotBlockFromCache) {
                        CBlock block;
                        bool ret = ReadBlockFromDisk(block, pBestIndex, consensusParams);
                        assert(ret);
                        CBlockHeaderAndShortTxIDs cmpctblock(block);
                        connman->PushMessage(pto, msgMaker.Make(NetMsgType::CMPCTBLOCK, cmpctblock));
                    }
                    state.pindexBestHeaderSent = pBestIndex;
                } else if (state.fPreferHeaders) {
                    if (vHeaders.size() > 1) {
                        LogPrint(BCLog::NET, "%s: %u headers, range (%s, %s), to peer=%d\n", __func__,
                                vHeaders.size(),
                                vHeaders.front().GetHash().ToString(),
                                vHeaders.back().GetHash().ToString(), pto->GetId());
                    } else {
                        LogPrint(BCLog::NET, "%s: sending header %s to peer=%d\n", __func__,
                                vHeaders.front().GetHash().ToString(), pto->GetId());
                    }
                    connman->PushMessage(pto, msgMaker.Make(NetMsgType::HEADERS, vHeaders));
                    state.pindexBestHeaderSent = pBestIndex;
                } else
                    fRevertToInv = true;
            }
            if (fRevertToInv) {
                // If falling back to using an inv, just try to inv the tip.
                // The last entry in vBlockHashesToAnnounce was our tip at some point
                // in the past.
                if (!pto->vBlockHashesToAnnounce.empty()) {
                    const uint256 &hashToAnnounce = pto->vBlockHashesToAnnounce.back();
                    BlockMap::iterator mi = mapBlockIndex.find(hashToAnnounce);
                    assert(mi != mapBlockIndex.end());
                    const CBlockIndex *pindex = mi->second;

                    // Warn if we're announcing a block that is not on the main chain.
                    // This should be very rare and could be optimized out.
                    // Just log for now.
                    if (chainActive[pindex->nHeight] != pindex) {
                        LogPrint(BCLog::NET, "Announcing block %s not on main chain (tip=%s)\n",
                            hashToAnnounce.ToString(), chainActive.Tip()->GetBlockHash().ToString());
                    }

                    // If the peer's chain has this block, don't inv it back.
                    if (!PeerHasHeader(&state, pindex)) {
                        pto->PushInventory(CInv(MSG_BLOCK, hashToAnnounce));
                        LogPrint(BCLog::NET, "%s: sending inv peer=%d hash=%s\n", __func__,
                            pto->GetId(), hashToAnnounce.ToString());
                    }
                }
            }
            pto->vBlockHashesToAnnounce.clear();
        }

        //
        // Message: inventory
        //
        std::vector<CInv> vInv;
        {
            size_t reserve = std::min<size_t>(pto->setInventoryTxToSend.size(), INVENTORY_BROADCAST_MAX_PER_1MB_BLOCK * MaxBlockSize(true) / 1000000);
            reserve = std::max<size_t>(reserve, pto->vInventoryBlockToSend.size());
            reserve = std::min<size_t>(reserve, MAX_INV_SZ);
            vInv.reserve(reserve);

            LOCK2(mempool.cs, pto->cs_inventory);

            // Add blocks
            for (const uint256& hash : pto->vInventoryBlockToSend) {
                vInv.push_back(CInv(MSG_BLOCK, hash));
                if (vInv.size() == MAX_INV_SZ) {
                    connman->PushMessage(pto, msgMaker.Make(NetMsgType::INV, vInv));
                    vInv.clear();
                }
            }
            pto->vInventoryBlockToSend.clear();

            // Check whether periodic sends should happen
            // Note: If this node is running in a Masternode mode, it makes no sense to delay outgoing txes
            // because we never produce any txes ourselves i.e. no privacy is lost in this case.
            bool fSendTrickle = pto->fWhitelisted || fMasternodeMode;
            if (pto->nNextInvSend < current_time) {
                fSendTrickle = true;
                if (pto->fInbound) {
                    pto->nNextInvSend = std::chrono::microseconds{connman->PoissonNextSendInbound(current_time.count(), INVENTORY_BROADCAST_INTERVAL)};
                } else {
                    // Use half the delay for regular outbound peers, as there is less privacy concern for them.
                    // and quarter the delay for Masternode outbound peers, as there is even less privacy concern in this case.
                    pto->nNextInvSend = PoissonNextSend(current_time, std::chrono::seconds{INVENTORY_BROADCAST_INTERVAL >> 1 >> !pto->verifiedProRegTxHash.IsNull()});
                }
            }

            // Time to send but the peer has requested we not relay transactions.
            if (fSendTrickle) {
                LOCK(pto->cs_filter);
                if (!pto->fRelayTxes) pto->setInventoryTxToSend.clear();
            }

            // Respond to BIP35 mempool requests
            if (fSendTrickle && pto->fSendMempool) {
                auto vtxinfo = mempool.infoAll();
                pto->fSendMempool = false;

                LOCK(pto->cs_filter);

                for (const auto& txinfo : vtxinfo) {
                    const uint256& hash = txinfo.tx->GetHash();
                    int nInvType = MSG_TX;
                    if (CPrivateSend::GetDSTX(hash)) {
                        nInvType = MSG_DSTX;
                    }
                    CInv inv(nInvType, hash);
                    pto->setInventoryTxToSend.erase(hash);
                    if (pto->pfilter) {
                        if (!pto->pfilter->IsRelevantAndUpdate(*txinfo.tx)) continue;
                    }
                    pto->filterInventoryKnown.insert(hash);

                    LogPrint(BCLog::NET, "SendMessages -- queued inv: %s  index=%d peer=%d\n", inv.ToString(), vInv.size(), pto->GetId());
                    vInv.push_back(inv);
                    if (vInv.size() == MAX_INV_SZ) {
                        LogPrint(BCLog::NET, "SendMessages -- pushing inv's: count=%d peer=%d\n", vInv.size(), pto->GetId());
                        connman->PushMessage(pto, msgMaker.Make(NetMsgType::INV, vInv));
                        vInv.clear();
                    }

                    uint256 islockHash;
                    if (!llmq::quorumInstantSendManager->GetInstantSendLockHashByTxid(hash, islockHash)) continue;
                    CInv islockInv(MSG_ISLOCK, islockHash);
                    pto->filterInventoryKnown.insert(islockHash);

                    LogPrint(BCLog::NET, "SendMessages -- queued inv: %s  index=%d peer=%d\n", inv.ToString(), vInv.size(), pto->GetId());
                    vInv.push_back(inv);
                    if (vInv.size() == MAX_INV_SZ) {
                        LogPrint(BCLog::NET, "SendMessages -- pushing inv's: count=%d peer=%d\n", vInv.size(), pto->GetId());
                        connman->PushMessage(pto, msgMaker.Make(NetMsgType::INV, vInv));
                        vInv.clear();
                    }
                }
                pto->timeLastMempoolReq = GetTime();
            }

            // Determine transactions to relay
            if (fSendTrickle) {
                // Produce a vector with all candidates for sending
                std::vector<std::set<uint256>::iterator> vInvTx;
                vInvTx.reserve(pto->setInventoryTxToSend.size());
                for (std::set<uint256>::iterator it = pto->setInventoryTxToSend.begin(); it != pto->setInventoryTxToSend.end(); it++) {
                    vInvTx.push_back(it);
                }
                // Topologically and fee-rate sort the inventory we send for privacy and priority reasons.
                // A heap is used so that not all items need sorting if only a few are being sent.
                CompareInvMempoolOrder compareInvMempoolOrder(&mempool);
                std::make_heap(vInvTx.begin(), vInvTx.end(), compareInvMempoolOrder);
                // No reason to drain out at many times the network's capacity,
                // especially since we have many peers and some will draw much shorter delays.
                unsigned int nRelayedTransactions = 0;
                LOCK(pto->cs_filter);
                while (!vInvTx.empty() && nRelayedTransactions < INVENTORY_BROADCAST_MAX_PER_1MB_BLOCK * MaxBlockSize(true) / 1000000) {
                    // Fetch the top element from the heap
                    std::pop_heap(vInvTx.begin(), vInvTx.end(), compareInvMempoolOrder);
                    std::set<uint256>::iterator it = vInvTx.back();
                    vInvTx.pop_back();
                    uint256 hash = *it;
                    // Remove it from the to-be-sent set
                    pto->setInventoryTxToSend.erase(it);
                    // Check if not in the filter already
                    if (pto->filterInventoryKnown.contains(hash)) {
                        continue;
                    }
                    // Not in the mempool anymore? don't bother sending it.
                    auto txinfo = mempool.info(hash);
                    if (!txinfo.tx) {
                        continue;
                    }
                    if (pto->pfilter && !pto->pfilter->IsRelevantAndUpdate(*txinfo.tx)) continue;
                    // Send
                    int nInvType = MSG_TX;
                    if (CPrivateSend::GetDSTX(hash)) {
                        nInvType = MSG_DSTX;
                    }
                    vInv.push_back(CInv(nInvType, hash));
                    nRelayedTransactions++;
                    {
                        // Expire old relay messages
                        while (!vRelayExpiration.empty() && vRelayExpiration.front().first < nNow)
                        {
                            mapRelay.erase(vRelayExpiration.front().second);
                            vRelayExpiration.pop_front();
                        }

                        auto ret = mapRelay.insert(std::make_pair(hash, std::move(txinfo.tx)));
                        if (ret.second) {
                            vRelayExpiration.push_back(std::make_pair(nNow + 15 * 60 * 1000000, ret.first));
                        }
                    }
                    if (vInv.size() == MAX_INV_SZ) {
                        connman->PushMessage(pto, msgMaker.Make(NetMsgType::INV, vInv));
                        vInv.clear();
                    }
                    pto->filterInventoryKnown.insert(hash);
                }
            }

            // Send non-tx/non-block inventory items
            for (const auto& inv : pto->vInventoryOtherToSend) {
                if (pto->filterInventoryKnown.contains(inv.hash)) {
                    continue;
                }
                vInv.push_back(inv);
                pto->filterInventoryKnown.insert(inv.hash);
                if (vInv.size() == MAX_INV_SZ) {
                    connman->PushMessage(pto, msgMaker.Make(NetMsgType::INV, vInv));
                    vInv.clear();
                }
            }
            pto->vInventoryOtherToSend.clear();
        }
        if (!vInv.empty())
            connman->PushMessage(pto, msgMaker.Make(NetMsgType::INV, vInv));

        // Detect whether we're stalling
        current_time = GetTime<std::chrono::microseconds>();
        // nNow is the current system time (GetTimeMicros is not mockable) and
        // should be replaced by the mockable current_time eventually
        nNow = GetTimeMicros();
        if (state.nStallingSince && state.nStallingSince < nNow - 1000000 * BLOCK_STALLING_TIMEOUT) {
            // Stalling only triggers when the block download window cannot move. During normal steady state,
            // the download window should be much larger than the to-be-downloaded set of blocks, so disconnection
            // should only happen during initial block download.
            LogPrintf("Peer=%d is stalling block download, disconnecting\n", pto->GetId());
            pto->fDisconnect = true;
            return true;
        }
        // In case there is a block that has been in flight from this peer for 2 + 0.5 * N times the block interval
        // (with N the number of peers from which we're downloading validated blocks), disconnect due to timeout.
        // We compensate for other peers to prevent killing off peers due to our own downstream link
        // being saturated. We only count validated in-flight blocks so peers can't advertise non-existing block hashes
        // to unreasonably increase our timeout.
        if (state.vBlocksInFlight.size() > 0) {
            QueuedBlock &queuedBlock = state.vBlocksInFlight.front();
            int nOtherPeersWithValidatedDownloads = nPeersWithValidatedDownloads - (state.nBlocksInFlightValidHeaders > 0);
            if (nNow > state.nDownloadingSince + consensusParams.nPowTargetSpacing * (BLOCK_DOWNLOAD_TIMEOUT_BASE + BLOCK_DOWNLOAD_TIMEOUT_PER_PEER * nOtherPeersWithValidatedDownloads)) {
                LogPrintf("Timeout downloading block %s from peer=%d, disconnecting\n", queuedBlock.hash.ToString(), pto->GetId());
                pto->fDisconnect = true;
                return true;
            }
        }
        // Check for headers sync timeouts
        if (state.fSyncStarted && state.nHeadersSyncTimeout < std::numeric_limits<int64_t>::max()) {
            // Detect whether this is a stalling initial-headers-sync peer
            if (pindexBestHeader->GetBlockTime() <= GetAdjustedTime() - nMaxTipAge) {
                if (nNow > state.nHeadersSyncTimeout && nSyncStarted == 1 && (nPreferredDownload - state.fPreferredDownload >= 1)) {
                    // Disconnect a (non-whitelisted) peer if it is our only sync peer,
                    // and we have others we could be using instead.
                    // Note: If all our peers are inbound, then we won't
                    // disconnect our sync peer for stalling; we have bigger
                    // problems if we can't get any outbound peers.
                    if (!pto->fWhitelisted) {
                        LogPrintf("Timeout downloading headers from peer=%d, disconnecting\n", pto->GetId());
                        pto->fDisconnect = true;
                        return true;
                    } else {
                        LogPrintf("Timeout downloading headers from whitelisted peer=%d, not disconnecting\n", pto->GetId());
                        // Reset the headers sync state so that we have a
                        // chance to try downloading from a different peer.
                        // Note: this will also result in at least one more
                        // getheaders message to be sent to
                        // this peer (eventually).
                        state.fSyncStarted = false;
                        nSyncStarted--;
                        state.nHeadersSyncTimeout = 0;
                    }
                }
            } else {
                // After we've caught up once, reset the timeout so we can't trigger
                // disconnect later.
                state.nHeadersSyncTimeout = std::numeric_limits<int64_t>::max();
            }
        }

        // Check that outbound peers have reasonable chains
        // GetTime() is used by this anti-DoS logic so we can test this using mocktime
        ConsiderEviction(pto, GetTime());

        //
        // Message: getdata (blocks)
        //
        std::vector<CInv> vGetData;
        if (!pto->fClient && !pto->fMasternode && ((fFetch && !pto->m_limited_node) || !IsInitialBlockDownload()) && state.nBlocksInFlight < MAX_BLOCKS_IN_TRANSIT_PER_PEER) {
            std::vector<const CBlockIndex*> vToDownload;
            NodeId staller = -1;
            FindNextBlocksToDownload(pto->GetId(), MAX_BLOCKS_IN_TRANSIT_PER_PEER - state.nBlocksInFlight, vToDownload, staller, consensusParams);
            for (const CBlockIndex *pindex : vToDownload) {
                vGetData.push_back(CInv(MSG_BLOCK, pindex->GetBlockHash()));
                MarkBlockAsInFlight(pto->GetId(), pindex->GetBlockHash(), pindex);
                LogPrint(BCLog::NET, "Requesting block %s (%d) peer=%d\n", pindex->GetBlockHash().ToString(),
                    pindex->nHeight, pto->GetId());
            }
            if (state.nBlocksInFlight == 0 && staller != -1) {
                if (State(staller)->nStallingSince == 0) {
                    State(staller)->nStallingSince = nNow;
                    LogPrint(BCLog::NET, "Stall started peer=%d\n", staller);
                }
            }
        }

        //
        // Message: getdata (non-blocks)
        //

        // For robustness, expire old requests after a long timeout, so that
        // we can resume downloading objects from a peer even if they
        // were unresponsive in the past.
        // Eventually we should consider disconnecting peers, but this is
        // conservative.
        if (state.m_object_download.m_check_expiry_timer <= current_time) {
            for (auto it=state.m_object_download.m_object_in_flight.begin(); it != state.m_object_download.m_object_in_flight.end();) {
                if (it->second <= current_time - GetObjectExpiryInterval(it->first.type)) {
                    LogPrint(BCLog::NET, "timeout of inflight object %s from peer=%d\n", it->first.ToString(), pto->GetId());
                    state.m_object_download.m_object_announced.erase(it->first);
                    state.m_object_download.m_object_in_flight.erase(it++);
                } else {
                    ++it;
                }
            }
            // On average, we do this check every GetObjectExpiryInterval. Randomize
            // so that we're not doing this for all peers at the same time.
            state.m_object_download.m_check_expiry_timer = current_time + GetObjectExpiryInterval(MSG_TX)/2 + GetRandMicros(GetObjectExpiryInterval(MSG_TX));
        }

        // DASH this code also handles non-TXs (Dash specific messages)
        auto& object_process_time = state.m_object_download.m_object_process_time;
        while (!object_process_time.empty() && object_process_time.begin()->first <= current_time && state.m_object_download.m_object_in_flight.size() < MAX_PEER_OBJECT_IN_FLIGHT) {
            const CInv inv = object_process_time.begin()->second;
            // Erase this entry from object_process_time (it may be added back for
            // processing at a later time, see below)
            object_process_time.erase(object_process_time.begin());
            if (g_erased_object_requests.count(inv.hash)) {
                LogPrint(BCLog::NET, "%s -- GETDATA skipping inv=(%s), peer=%d\n", __func__, inv.ToString(), pto->GetId());
                state.m_object_download.m_object_announced.erase(inv);
                state.m_object_download.m_object_in_flight.erase(inv);
                continue;
            }
            if (!AlreadyHave(inv)) {
                // If this object was last requested more than GetObjectInterval ago,
                // then request.
                const auto last_request_time = GetObjectRequestTime(inv.hash);
                if (last_request_time <= current_time - GetObjectInterval(inv.type)) {
                    LogPrint(BCLog::NET, "Requesting %s peer=%d\n", inv.ToString(), pto->GetId());
                    vGetData.push_back(inv);
                    if (vGetData.size() >= MAX_GETDATA_SZ) {
                        connman->PushMessage(pto, msgMaker.Make(NetMsgType::GETDATA, vGetData));
                        vGetData.clear();
                    }
                    UpdateObjectRequestTime(inv.hash, current_time);
                    state.m_object_download.m_object_in_flight.emplace(inv, current_time);
                } else {
                    // This object is in flight from someone else; queue
                    // up processing to happen after the download times out
                    // (with a slight delay for inbound peers, to prefer
                    // requests to outbound peers).
                    const auto next_process_time = CalculateObjectGetDataTime(inv, current_time, !state.fPreferredDownload);
                    object_process_time.emplace(next_process_time, inv);
                    LogPrint(BCLog::NET, "%s -- GETDATA re-queue inv=(%s), next_process_time=%d, delta=%d, peer=%d\n", __func__, inv.ToString(), next_process_time.count(), (next_process_time - current_time).count(), pto->GetId());
                }
            } else {
                // We have already seen this object, no need to download.
                state.m_object_download.m_object_announced.erase(inv);
                state.m_object_download.m_object_in_flight.erase(inv);
                LogPrint(BCLog::NET, "%s -- GETDATA already seen inv=(%s), peer=%d\n", __func__, inv.ToString(), pto->GetId());
            }
        }


        if (!vGetData.empty()) {
            connman->PushMessage(pto, msgMaker.Make(NetMsgType::GETDATA, vGetData));
            LogPrint(BCLog::NET, "SendMessages -- GETDATA -- pushed size = %lu peer=%d\n", vGetData.size(), pto->GetId());
        }

    }
    return true;
}

class CNetProcessingCleanup
{
public:
    CNetProcessingCleanup() {}
    ~CNetProcessingCleanup() {
        // orphan transactions
        mapOrphanTransactions.clear();
        mapOrphanTransactionsByPrev.clear();
        nMapOrphanTransactionsSize = 0;
    }
} instance_of_cnetprocessingcleanup;