Move network-msg-processing code out of main to its own file

1 files changed, 3026 insertions, 0 deletions

diff --git a/src/net_processing.cpp b/src/net_processing.cpp
new file mode 100644
index 0000000000..78c864e96f
--- /dev/null
+++ b/src/net_processing.cpp
@@ -0,0 +1,3026 @@
+// 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 "main.h"
+#include "merkleblock.h"
+#include "net.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 "tinyformat.h"
+#include "txmempool.h"
+#include "ui_interface.h"
+#include "util.h"
+#include "utilmoneystr.h"
+#include "utilstrencodings.h"
+#include "validationinterface.h"
+
+#include <boost/thread.hpp>
+
+using namespace std;
+
+#if defined(NDEBUG)
+# error "Bitcoin cannot be compiled without assertions."
+#endif
+
+int64_t nTimeBestReceived = 0; // Used only to inform the wallet of when we last received a block
+
+struct IteratorComparator
+{
+    template<typename I>
+    bool operator()(const I& a, const I& b)
+    {
+        return &(*a) < &(*b);
+    }
+};
+
+struct COrphanTx {
+    CTransaction tx;
+    NodeId fromPeer;
+    int64_t nTimeExpire;
+};
+map<uint256, COrphanTx> mapOrphanTransactions GUARDED_BY(cs_main);
+map<COutPoint, set<map<uint256, COrphanTx>::iterator, IteratorComparator>> mapOrphanTransactionsByPrev GUARDED_BY(cs_main);
+void EraseOrphansFor(NodeId peer) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+
+static const uint64_t RANDOMIZER_ID_ADDRESS_RELAY = 0x3cac0035b5866b90ULL; // SHA256("main address relay")[0:8]
+
+// Internal stuff
+namespace {
+    /** Number of nodes with fSyncStarted. */
+    int nSyncStarted = 0;
+
+    /**
+     * Sources of received blocks, saved to be able to send them reject
+     * messages or ban them when processing happens afterwards. Protected by
+     * cs_main.
+     * Set mapBlockSource[hash].second to false if the node should not be
+     * punished if the block is invalid.
+     */
+    map<uint256, std::pair<NodeId, bool>> mapBlockSource;
+
+    /**
+     * Filter for transactions that were recently rejected by
+     * AcceptToMemoryPool. These are not rerequested until the chain tip
+     * changes, at which point the entire filter is reset. Protected by
+     * cs_main.
+     *
+     * Without this filter we'd be re-requesting txs from each of our peers,
+     * increasing bandwidth consumption considerably. For instance, with 100
+     * peers, half of which relay a tx we don't accept, that might be a 50x
+     * bandwidth increase. A flooding attacker attempting to roll-over the
+     * filter using minimum-sized, 60byte, transactions might manage to send
+     * 1000/sec if we have fast peers, so we pick 120,000 to give our peers a
+     * two minute window to send invs to us.
+     *
+     * Decreasing the false positive rate is fairly cheap, so we pick one in a
+     * million to make it highly unlikely for users to have issues with this
+     * filter.
+     *
+     * Memory used: 1.3 MB
+     */
+    std::unique_ptr<CRollingBloomFilter> recentRejects;
+    uint256 hashRecentRejectsChainTip;
+
+    /** Blocks that are in flight, and that are in the queue to be downloaded. Protected by cs_main. */
+    struct QueuedBlock {
+        uint256 hash;
+        CBlockIndex* pindex;                                     //!< Optional.
+        bool fValidatedHeaders;                                  //!< Whether this block has validated headers at the time of request.
+        std::unique_ptr<PartiallyDownloadedBlock> partialBlock;  //!< Optional, used for CMPCTBLOCK downloads
+    };
+    map<uint256, pair<NodeId, list<QueuedBlock>::iterator> > mapBlocksInFlight;
+
+    /** Stack of nodes which we have set to announce using compact blocks */
+    list<NodeId> lNodesAnnouncingHeaderAndIDs;
+
+    /** Number of preferable block download peers. */
+    int nPreferredDownload = 0;
+
+    /** Number of peers from which we're downloading blocks. */
+    int nPeersWithValidatedDownloads = 0;
+
+    /** Relay map, protected by cs_main. */
+    typedef std::map<uint256, CTransactionRef> MapRelay;
+    MapRelay mapRelay;
+    /** Expiration-time ordered list of (expire time, relay map entry) pairs, protected by cs_main). */
+    std::deque<std::pair<int64_t, MapRelay::iterator>> vRelayExpiration;
+} // anon namespace
+
+//////////////////////////////////////////////////////////////////////////////
+//
+// Registration of network node signals.
+//
+
+namespace {
+
+struct CBlockReject {
+    unsigned char chRejectCode;
+    string strRejectReason;
+    uint256 hashBlock;
+};
+
+/**
+ * Maintain validation-specific state about nodes, protected by cs_main, instead
+ * by CNode's own locks. This simplifies asynchronous operation, where
+ * processing of incoming data is done after the ProcessMessage call returns,
+ * and we're no longer holding the node's locks.
+ */
+struct CNodeState {
+    //! The peer's address
+    const CService address;
+    //! Whether we have a fully established connection.
+    bool fCurrentlyConnected;
+    //! Accumulated misbehaviour score for this peer.
+    int nMisbehavior;
+    //! Whether this peer should be disconnected and banned (unless whitelisted).
+    bool fShouldBan;
+    //! String name of this peer (debugging/logging purposes).
+    const std::string name;
+    //! List of asynchronously-determined block rejections to notify this peer about.
+    std::vector<CBlockReject> rejects;
+    //! The best known block we know this peer has announced.
+    CBlockIndex *pindexBestKnownBlock;
+    //! The hash of the last unknown block this peer has announced.
+    uint256 hashLastUnknownBlock;
+    //! The last full block we both have.
+    CBlockIndex *pindexLastCommonBlock;
+    //! The best header we have sent our peer.
+    CBlockIndex *pindexBestHeaderSent;
+    //! Length of current-streak of unconnecting headers announcements
+    int nUnconnectingHeaders;
+    //! Whether we've started headers synchronization with this peer.
+    bool fSyncStarted;
+    //! Since when we're stalling block download progress (in microseconds), or 0.
+    int64_t nStallingSince;
+    list<QueuedBlock> vBlocksInFlight;
+    //! When the first entry in vBlocksInFlight started downloading. Don't care when vBlocksInFlight is empty.
+    int64_t nDownloadingSince;
+    int nBlocksInFlight;
+    int nBlocksInFlightValidHeaders;
+    //! Whether we consider this a preferred download peer.
+    bool fPreferredDownload;
+    //! Whether this peer wants invs or headers (when possible) for block announcements.
+    bool fPreferHeaders;
+    //! Whether this peer wants invs or cmpctblocks (when possible) for block announcements.
+    bool fPreferHeaderAndIDs;
+    /**
+      * Whether this peer will send us cmpctblocks if we request them.
+      * This is not used to gate request logic, as we really only care about fSupportsDesiredCmpctVersion,
+      * but is used as a flag to "lock in" the version of compact blocks (fWantsCmpctWitness) we send.
+      */
+    bool fProvidesHeaderAndIDs;
+    //! Whether this peer can give us witnesses
+    bool fHaveWitness;
+    //! Whether this peer wants witnesses in cmpctblocks/blocktxns
+    bool fWantsCmpctWitness;
+    /**
+     * If we've announced NODE_WITNESS to this peer: whether the peer sends witnesses in cmpctblocks/blocktxns,
+     * otherwise: whether this peer sends non-witnesses in cmpctblocks/blocktxns.
+     */
+    bool fSupportsDesiredCmpctVersion;
+
+    CNodeState(CAddress addrIn, std::string addrNameIn) : address(addrIn), name(addrNameIn) {
+        fCurrentlyConnected = false;
+        nMisbehavior = 0;
+        fShouldBan = false;
+        pindexBestKnownBlock = NULL;
+        hashLastUnknownBlock.SetNull();
+        pindexLastCommonBlock = NULL;
+        pindexBestHeaderSent = NULL;
+        nUnconnectingHeaders = 0;
+        fSyncStarted = false;
+        nStallingSince = 0;
+        nDownloadingSince = 0;
+        nBlocksInFlight = 0;
+        nBlocksInFlightValidHeaders = 0;
+        fPreferredDownload = false;
+        fPreferHeaders = false;
+        fPreferHeaderAndIDs = false;
+        fProvidesHeaderAndIDs = false;
+        fHaveWitness = false;
+        fWantsCmpctWitness = false;
+        fSupportsDesiredCmpctVersion = false;
+    }
+};
+
+/** Map maintaining per-node state. Requires cs_main. */
+map<NodeId, CNodeState> mapNodeState;
+
+// Requires cs_main.
+CNodeState *State(NodeId pnode) {
+    map<NodeId, CNodeState>::iterator it = mapNodeState.find(pnode);
+    if (it == mapNodeState.end())
+        return NULL;
+    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)
+{
+    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);
+
+    connman.PushMessage(pnode, CNetMsgMaker(INIT_PROTO_VERSION).Make(NetMsgType::VERSION, PROTOCOL_VERSION, (uint64_t)nLocalNodeServices, nTime, addrYou, addrMe,
+            nonce, strSubVersion, nNodeStartingHeight, ::fRelayTxes));
+
+    if (fLogIPs)
+        LogPrint("net", "send version message: version %d, blocks=%d, us=%s, them=%s, peer=%d\n", PROTOCOL_VERSION, nNodeStartingHeight, addrMe.ToString(), addrYou.ToString(), nodeid);
+    else
+        LogPrint("net", "send version message: version %d, blocks=%d, us=%s, peer=%d\n", PROTOCOL_VERSION, nNodeStartingHeight, addrMe.ToString(), nodeid);
+}
+
+void InitializeNode(CNode *pnode, CConnman& connman) {
+    CAddress addr = pnode->addr;
+    std::string addrName = pnode->addrName;
+    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 FinalizeNode(NodeId nodeid, bool& fUpdateConnectionTime) {
+    fUpdateConnectionTime = false;
+    LOCK(cs_main);
+    CNodeState *state = State(nodeid);
+
+    if (state->fSyncStarted)
+        nSyncStarted--;
+
+    if (state->nMisbehavior == 0 && state->fCurrentlyConnected) {
+        fUpdateConnectionTime = true;
+    }
+
+    BOOST_FOREACH(const QueuedBlock& entry, state->vBlocksInFlight) {
+        mapBlocksInFlight.erase(entry.hash);
+    }
+    EraseOrphansFor(nodeid);
+    nPreferredDownload -= state->fPreferredDownload;
+    nPeersWithValidatedDownloads -= (state->nBlocksInFlightValidHeaders != 0);
+    assert(nPeersWithValidatedDownloads >= 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);
+    }
+}
+
+// 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) {
+    map<uint256, pair<NodeId, list<QueuedBlock>::iterator> >::iterator itInFlight = mapBlocksInFlight.find(hash);
+    if (itInFlight != mapBlocksInFlight.end()) {
+        CNodeState *state = State(itInFlight->second.first);
+        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 Consensus::Params& consensusParams, CBlockIndex *pindex = NULL, list<QueuedBlock>::iterator **pit = NULL) {
+    CNodeState *state = State(nodeid);
+    assert(state != NULL);
+
+    // Short-circuit most stuff in case its from the same node
+    map<uint256, pair<NodeId, list<QueuedBlock>::iterator> >::iterator itInFlight = mapBlocksInFlight.find(hash);
+    if (itInFlight != mapBlocksInFlight.end() && itInFlight->second.first == nodeid) {
+        *pit = &itInFlight->second.second;
+        return false;
+    }
+
+    // Make sure it's not listed somewhere already.
+    MarkBlockAsReceived(hash);
+
+    list<QueuedBlock>::iterator it = state->vBlocksInFlight.insert(state->vBlocksInFlight.end(),
+            {hash, pindex, pindex != NULL, std::unique_ptr<PartiallyDownloadedBlock>(pit ? new PartiallyDownloadedBlock(&mempool) : NULL)});
+    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 != NULL) {
+        nPeersWithValidatedDownloads++;
+    }
+    itInFlight = mapBlocksInFlight.insert(std::make_pair(hash, std::make_pair(nodeid, it))).first;
+    if (pit)
+        *pit = &itInFlight->second.second;
+    return true;
+}
+
+/** Check whether the last unknown block a peer advertised is not yet known. */
+void ProcessBlockAvailability(NodeId nodeid) {
+    CNodeState *state = State(nodeid);
+    assert(state != NULL);
+
+    if (!state->hashLastUnknownBlock.IsNull()) {
+        BlockMap::iterator itOld = mapBlockIndex.find(state->hashLastUnknownBlock);
+        if (itOld != mapBlockIndex.end() && itOld->second->nChainWork > 0) {
+            if (state->pindexBestKnownBlock == NULL || itOld->second->nChainWork >= state->pindexBestKnownBlock->nChainWork)
+                state->pindexBestKnownBlock = itOld->second;
+            state->hashLastUnknownBlock.SetNull();
+        }
+    }
+}
+
+/** Update tracking information about which blocks a peer is assumed to have. */
+void UpdateBlockAvailability(NodeId nodeid, const uint256 &hash) {
+    CNodeState *state = State(nodeid);
+    assert(state != NULL);
+
+    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 == NULL || 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(const CNodeState* nodestate, CNode* pfrom, CConnman& connman) {
+    if (!nodestate->fSupportsDesiredCmpctVersion) {
+        // Never ask from peers who can't provide witnesses.
+        return;
+    }
+    if (nodestate->fProvidesHeaderAndIDs) {
+        for (std::list<NodeId>::iterator it = lNodesAnnouncingHeaderAndIDs.begin(); it != lNodesAnnouncingHeaderAndIDs.end(); it++) {
+            if (*it == pfrom->GetId()) {
+                lNodesAnnouncingHeaderAndIDs.erase(it);
+                lNodesAnnouncingHeaderAndIDs.push_back(pfrom->GetId());
+                return;
+            }
+        }
+        bool fAnnounceUsingCMPCTBLOCK = false;
+        uint64_t nCMPCTBLOCKVersion = (pfrom->GetLocalServices() & NODE_WITNESS) ? 2 : 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, fAnnounceUsingCMPCTBLOCK, nCMPCTBLOCKVersion](CNode* pnodeStop){
+                connman.PushMessage(pnodeStop, CNetMsgMaker(pnodeStop->GetSendVersion()).Make(NetMsgType::SENDCMPCT, fAnnounceUsingCMPCTBLOCK, nCMPCTBLOCKVersion));
+                return true;
+            });
+            lNodesAnnouncingHeaderAndIDs.pop_front();
+        }
+        fAnnounceUsingCMPCTBLOCK = true;
+        connman.PushMessage(pfrom, CNetMsgMaker(pfrom->GetSendVersion()).Make(NetMsgType::SENDCMPCT, fAnnounceUsingCMPCTBLOCK, nCMPCTBLOCKVersion));
+        lNodesAnnouncingHeaderAndIDs.push_back(pfrom->GetId());
+    }
+}
+
+// Requires cs_main
+bool CanDirectFetch(const Consensus::Params &consensusParams)
+{
+    return chainActive.Tip()->GetBlockTime() > GetAdjustedTime() - consensusParams.nPowTargetSpacing * 20;
+}
+
+// Requires cs_main
+bool PeerHasHeader(CNodeState *state, 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;
+}
+
+/** Find the last common ancestor two blocks have.
+ *  Both pa and pb must be non-NULL. */
+CBlockIndex* LastCommonAncestor(CBlockIndex* pa, CBlockIndex* pb) {
+    if (pa->nHeight > pb->nHeight) {
+        pa = pa->GetAncestor(pb->nHeight);
+    } else if (pb->nHeight > pa->nHeight) {
+        pb = pb->GetAncestor(pa->nHeight);
+    }
+
+    while (pa != pb && pa && pb) {
+        pa = pa->pprev;
+        pb = pb->pprev;
+    }
+
+    // Eventually all chain branches meet at the genesis block.
+    assert(pa == pb);
+    return pa;
+}
+
+/** Update pindexLastCommonBlock and add not-in-flight missing successors to vBlocks, until it has
+ *  at most count entries. */
+void FindNextBlocksToDownload(NodeId nodeid, unsigned int count, std::vector<CBlockIndex*>& vBlocks, NodeId& nodeStaller, const Consensus::Params& consensusParams) {
+    if (count == 0)
+        return;
+
+    vBlocks.reserve(vBlocks.size() + count);
+    CNodeState *state = State(nodeid);
+    assert(state != NULL);
+
+    // Make sure pindexBestKnownBlock is up to date, we'll need it.
+    ProcessBlockAvailability(nodeid);
+
+    if (state->pindexBestKnownBlock == NULL || state->pindexBestKnownBlock->nChainWork < chainActive.Tip()->nChainWork) {
+        // This peer has nothing interesting.
+        return;
+    }
+
+    if (state->pindexLastCommonBlock == NULL) {
+        // 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<CBlockIndex*> vToFetch;
+    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).
+        BOOST_FOREACH(CBlockIndex* pindex, vToFetch) {
+            if (!pindex->IsValid(BLOCK_VALID_TREE)) {
+                // We consider the chain that this peer is on invalid.
+                return;
+            }
+            if (!State(nodeid)->fHaveWitness && IsWitnessEnabled(pindex->pprev, consensusParams)) {
+                // We wouldn't download this block or its descendants from this peer.
+                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;
+            }
+        }
+    }
+}
+
+} // anon namespace
+
+bool GetNodeStateStats(NodeId nodeid, CNodeStateStats &stats) {
+    LOCK(cs_main);
+    CNodeState *state = State(nodeid);
+    if (state == NULL)
+        return false;
+    stats.nMisbehavior = state->nMisbehavior;
+    stats.nSyncHeight = state->pindexBestKnownBlock ? state->pindexBestKnownBlock->nHeight : -1;
+    stats.nCommonHeight = state->pindexLastCommonBlock ? state->pindexLastCommonBlock->nHeight : -1;
+    BOOST_FOREACH(const QueuedBlock& queue, state->vBlocksInFlight) {
+        if (queue.pindex)
+            stats.vHeightInFlight.push_back(queue.pindex->nHeight);
+    }
+    return true;
+}
+
+void RegisterNodeSignals(CNodeSignals& nodeSignals)
+{
+    nodeSignals.ProcessMessages.connect(&ProcessMessages);
+    nodeSignals.SendMessages.connect(&SendMessages);
+    nodeSignals.InitializeNode.connect(&InitializeNode);
+    nodeSignals.FinalizeNode.connect(&FinalizeNode);
+}
+
+void UnregisterNodeSignals(CNodeSignals& nodeSignals)
+{
+    nodeSignals.ProcessMessages.disconnect(&ProcessMessages);
+    nodeSignals.SendMessages.disconnect(&SendMessages);
+    nodeSignals.InitializeNode.disconnect(&InitializeNode);
+    nodeSignals.FinalizeNode.disconnect(&FinalizeNode);
+}
+
+//////////////////////////////////////////////////////////////////////////////
+//
+// mapOrphanTransactions
+//
+
+bool AddOrphanTx(const CTransaction& tx, NodeId peer) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
+{
+    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 = GetTransactionWeight(tx);
+    if (sz >= MAX_STANDARD_TX_WEIGHT)
+    {
+        LogPrint("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});
+    assert(ret.second);
+    BOOST_FOREACH(const CTxIn& txin, tx.vin) {
+        mapOrphanTransactionsByPrev[txin.prevout].insert(ret.first);
+    }
+
+    LogPrint("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(cs_main)
+{
+    map<uint256, COrphanTx>::iterator it = mapOrphanTransactions.find(hash);
+    if (it == mapOrphanTransactions.end())
+        return 0;
+    BOOST_FOREACH(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);
+    }
+    mapOrphanTransactions.erase(it);
+    return 1;
+}
+
+void EraseOrphansFor(NodeId peer)
+{
+    int nErased = 0;
+    map<uint256, COrphanTx>::iterator iter = mapOrphanTransactions.begin();
+    while (iter != mapOrphanTransactions.end())
+    {
+        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("mempool", "Erased %d orphan tx from peer %d\n", nErased, peer);
+}
+
+
+unsigned int LimitOrphanTxSize(unsigned int nMaxOrphans) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
+{
+    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;
+        map<uint256, COrphanTx>::iterator iter = mapOrphanTransactions.begin();
+        while (iter != mapOrphanTransactions.end())
+        {
+            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("mempool", "Erased %d orphan tx due to expiration\n", nErased);
+    }
+    while (mapOrphanTransactions.size() > nMaxOrphans)
+    {
+        // Evict a random orphan:
+        uint256 randomhash = GetRandHash();
+        map<uint256, COrphanTx>::iterator it = mapOrphanTransactions.lower_bound(randomhash);
+        if (it == mapOrphanTransactions.end())
+            it = mapOrphanTransactions.begin();
+        EraseOrphanTx(it->first);
+        ++nEvicted;
+    }
+    return nEvicted;
+}
+
+// Requires cs_main.
+void Misbehaving(NodeId pnode, int howmuch)
+{
+    if (howmuch == 0)
+        return;
+
+    CNodeState *state = State(pnode);
+    if (state == NULL)
+        return;
+
+    state->nMisbehavior += howmuch;
+    int banscore = GetArg("-banscore", DEFAULT_BANSCORE_THRESHOLD);
+    if (state->nMisbehavior >= banscore && state->nMisbehavior - howmuch < banscore)
+    {
+        LogPrintf("%s: %s peer=%d (%d -> %d) BAN THRESHOLD EXCEEDED\n", __func__, state->name, pnode, state->nMisbehavior-howmuch, state->nMisbehavior);
+        state->fShouldBan = true;
+    } else
+        LogPrintf("%s: %s peer=%d (%d -> %d)\n", __func__, state->name, pnode, state->nMisbehavior-howmuch, state->nMisbehavior);
+}
+
+
+
+
+
+
+
+
+//////////////////////////////////////////////////////////////////////////////
+//
+// blockchain -> download logic notification
+//
+
+PeerLogicValidation::PeerLogicValidation(CConnman* connmanIn) : connman(connmanIn) {
+    // Initialize global variables that cannot be constructed at startup.
+    recentRejects.reset(new CRollingBloomFilter(120000, 0.000001));
+}
+
+void PeerLogicValidation::SyncTransaction(const CTransaction& tx, const CBlockIndex* pindex, int nPosInBlock) {
+    if (nPosInBlock == CMainSignals::SYNC_TRANSACTION_NOT_IN_BLOCK)
+        return;
+
+    LOCK(cs_main);
+
+    std::vector<uint256> vOrphanErase;
+    // Which orphan pool entries must we evict?
+    for (size_t j = 0; j < tx.vin.size(); j++) {
+        auto itByPrev = mapOrphanTransactionsByPrev.find(tx.vin[j].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;
+        BOOST_FOREACH(uint256 &orphanHash, vOrphanErase) {
+            nErased += EraseOrphanTx(orphanHash);
+        }
+        LogPrint("mempool", "Erased %d orphan tx included or conflicted by block\n", nErased);
+    }
+}
+
+void PeerLogicValidation::UpdatedBlockTip(const CBlockIndex *pindexNew, const CBlockIndex *pindexFork, bool fInitialDownload) {
+    const int nNewHeight = pindexNew->nHeight;
+    connman->SetBestHeight(nNewHeight);
+
+    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 (nNewHeight > (pnode->nStartingHeight != -1 ? pnode->nStartingHeight - 2000 : 0)) {
+                BOOST_REVERSE_FOREACH(const uint256& hash, vHashes) {
+                    pnode->PushBlockHash(hash);
+                }
+            }
+        });
+    }
+
+    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)) {
+        if (it != mapBlockSource.end() && State(it->second.first)) {
+            assert (state.GetRejectCode() < REJECT_INTERNAL); // Blocks are never rejected with internal reject codes
+            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);
+        }
+    }
+    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_WITNESS_TX:
+        {
+            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();
+            }
+
+            // Use pcoinsTip->HaveCoinsInCache as a quick approximation to exclude
+            // requesting or processing some txs which have already been included in a block
+            return recentRejects->contains(inv.hash) ||
+                   mempool.exists(inv.hash) ||
+                   mapOrphanTransactions.count(inv.hash) ||
+                   pcoinsTip->HaveCoinsInCache(inv.hash);
+        }
+    case MSG_BLOCK:
+    case MSG_WITNESS_BLOCK:
+        return mapBlockIndex.count(inv.hash);
+    }
+    // Don't know what it is, just say we already got one
+    return true;
+}
+
+static void RelayTransaction(const CTransaction& tx, CConnman& connman)
+{
+    CInv inv(MSG_TX, tx.GetHash());
+    connman.ForEachNode([&inv](CNode* pnode)
+    {
+        pnode->PushInventory(inv);
+    });
+}
+
+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->id).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 ProcessGetData(CNode* pfrom, const Consensus::Params& consensusParams, CConnman& connman)
+{
+    std::deque<CInv>::iterator it = pfrom->vRecvGetData.begin();
+    unsigned int nMaxSendBufferSize = connman.GetSendBufferSize();
+    vector<CInv> vNotFound;
+    CNetMsgMaker msgMaker(pfrom->GetSendVersion());
+    LOCK(cs_main);
+
+    while (it != pfrom->vRecvGetData.end()) {
+        // Don't bother if send buffer is too full to respond anyway
+        if (pfrom->nSendSize >= nMaxSendBufferSize)
+            break;
+
+        const CInv &inv = *it;
+        {
+            boost::this_thread::interruption_point();
+            it++;
+
+            if (inv.type == MSG_BLOCK || inv.type == MSG_FILTERED_BLOCK || inv.type == MSG_CMPCT_BLOCK || inv.type == MSG_WITNESS_BLOCK)
+            {
+                bool send = false;
+                BlockMap::iterator mi = mapBlockIndex.find(inv.hash);
+                if (mi != mapBlockIndex.end())
+                {
+                    if (chainActive.Contains(mi->second)) {
+                        send = true;
+                    } else {
+                        static const int nOneMonth = 30 * 24 * 60 * 60;
+                        // To prevent fingerprinting attacks, only send blocks outside of the active
+                        // chain if they are valid, and no more than a month older (both in time, and in
+                        // best equivalent proof of work) than the best header chain we know about.
+                        send = mi->second->IsValid(BLOCK_VALID_SCRIPTS) && (pindexBestHeader != NULL) &&
+                            (pindexBestHeader->GetBlockTime() - mi->second->GetBlockTime() < nOneMonth) &&
+                            (GetBlockProofEquivalentTime(*pindexBestHeader, *mi->second, *pindexBestHeader, consensusParams) < nOneMonth);
+                        if (!send) {
+                            LogPrintf("%s: ignoring request from peer=%i for old block that isn't in the main chain\n", __func__, pfrom->GetId());
+                        }
+                    }
+                }
+                // disconnect node in case we have reached the outbound limit for serving historical blocks
+                // never disconnect whitelisted nodes
+                static const int nOneWeek = 7 * 24 * 60 * 60; // assume > 1 week = historical
+                if (send && connman.OutboundTargetReached(true) && ( ((pindexBestHeader != NULL) && (pindexBestHeader->GetBlockTime() - mi->second->GetBlockTime() > nOneWeek)) || inv.type == MSG_FILTERED_BLOCK) && !pfrom->fWhitelisted)
+                {
+                    LogPrint("net", "historical block serving limit reached, disconnect peer=%d\n", pfrom->GetId());
+
+                    //disconnect node
+                    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))
+                {
+                    // Send block from disk
+                    CBlock block;
+                    if (!ReadBlockFromDisk(block, (*mi).second, consensusParams))
+                        assert(!"cannot load block from disk");
+                    if (inv.type == MSG_BLOCK)
+                        connman.PushMessage(pfrom, msgMaker.Make(SERIALIZE_TRANSACTION_NO_WITNESS, NetMsgType::BLOCK, block));
+                    else if (inv.type == MSG_WITNESS_BLOCK)
+                        connman.PushMessage(pfrom, msgMaker.Make(NetMsgType::BLOCK, block));
+                    else if (inv.type == MSG_FILTERED_BLOCK)
+                    {
+                        bool sendMerkleBlock = false;
+                        CMerkleBlock merkleBlock;
+                        {
+                            LOCK(pfrom->cs_filter);
+                            if (pfrom->pfilter) {
+                                sendMerkleBlock = true;
+                                merkleBlock = CMerkleBlock(block, *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;
+                            BOOST_FOREACH(PairType& pair, merkleBlock.vMatchedTxn)
+                                connman.PushMessage(pfrom, msgMaker.Make(SERIALIZE_TRANSACTION_NO_WITNESS, NetMsgType::TX, *block.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.
+                        bool fPeerWantsWitness = State(pfrom->GetId())->fWantsCmpctWitness;
+                        int nSendFlags = fPeerWantsWitness ? 0 : SERIALIZE_TRANSACTION_NO_WITNESS;
+                        if (CanDirectFetch(consensusParams) && mi->second->nHeight >= chainActive.Height() - MAX_CMPCTBLOCK_DEPTH) {
+                            CBlockHeaderAndShortTxIDs cmpctblock(block, fPeerWantsWitness);
+                            connman.PushMessage(pfrom, msgMaker.Make(nSendFlags, NetMsgType::CMPCTBLOCK, cmpctblock));
+                        } else
+                            connman.PushMessage(pfrom, msgMaker.Make(nSendFlags, NetMsgType::BLOCK, block));
+                    }
+
+                    // 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.
+                        vector<CInv> vInv;
+                        vInv.push_back(CInv(MSG_BLOCK, chainActive.Tip()->GetBlockHash()));
+                        connman.PushMessage(pfrom, msgMaker.Make(NetMsgType::INV, vInv));
+                        pfrom->hashContinue.SetNull();
+                    }
+                }
+            }
+            else if (inv.type == MSG_TX || inv.type == MSG_WITNESS_TX)
+            {
+                // Send stream from relay memory
+                bool push = false;
+                auto mi = mapRelay.find(inv.hash);
+                int nSendFlags = (inv.type == MSG_TX ? SERIALIZE_TRANSACTION_NO_WITNESS : 0);
+                if (mi != mapRelay.end()) {
+                    connman.PushMessage(pfrom, msgMaker.Make(nSendFlags, 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) {
+                        connman.PushMessage(pfrom, msgMaker.Make(nSendFlags, NetMsgType::TX, *txinfo.tx));
+                        push = true;
+                    }
+                }
+                if (!push) {
+                    vNotFound.push_back(inv);
+                }
+            }
+
+            // Track requests for our stuff.
+            GetMainSignals().Inventory(inv.hash);
+
+            if (inv.type == MSG_BLOCK || inv.type == MSG_FILTERED_BLOCK || inv.type == MSG_CMPCT_BLOCK || inv.type == MSG_WITNESS_BLOCK)
+                break;
+        }
+    }
+
+    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. Currently only SPV clients actually 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.
+        connman.PushMessage(pfrom, msgMaker.Make(NetMsgType::NOTFOUND, vNotFound));
+    }
+}
+
+uint32_t GetFetchFlags(CNode* pfrom, CBlockIndex* pprev, const Consensus::Params& chainparams) {
+    uint32_t nFetchFlags = 0;
+    if ((pfrom->GetLocalServices() & NODE_WITNESS) && State(pfrom->GetId())->fHaveWitness) {
+        nFetchFlags |= MSG_WITNESS_FLAG;
+    }
+    return nFetchFlags;
+}
+
+bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv, int64_t nTimeReceived, const CChainParams& chainparams, CConnman& connman)
+{
+    unsigned int nMaxSendBufferSize = connman.GetSendBufferSize();
+
+    LogPrint("net", "received: %s (%u bytes) peer=%d\n", SanitizeString(strCommand), vRecv.size(), pfrom->id);
+    if (mapArgs.count("-dropmessagestest") && GetRand(atoi(mapArgs["-dropmessagestest"])) == 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::VERSION)
+    {
+        // Each connection can only send one version message
+        if (pfrom->nVersion != 0)
+        {
+            connman.PushMessage(pfrom, CNetMsgMaker(INIT_PROTO_VERSION).Make(NetMsgType::REJECT, strCommand, REJECT_DUPLICATE, 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;
+        vRecv >> pfrom->nVersion >> nServiceInt >> nTime >> addrMe;
+        pfrom->nServices = ServiceFlags(nServiceInt);
+        if (!pfrom->fInbound)
+        {
+            connman.SetServices(pfrom->addr, pfrom->nServices);
+        }
+        if (pfrom->nServicesExpected & ~pfrom->nServices)
+        {
+            LogPrint("net", "peer=%d does not offer the expected services (%08x offered, %08x expected); disconnecting\n", pfrom->id, pfrom->nServices, pfrom->nServicesExpected);
+            connman.PushMessage(pfrom, CNetMsgMaker(INIT_PROTO_VERSION).Make(NetMsgType::REJECT, strCommand, REJECT_NONSTANDARD,
+                               strprintf("Expected to offer services %08x", pfrom->nServicesExpected)));
+            pfrom->fDisconnect = true;
+            return false;
+        }
+
+        if (pfrom->nVersion < MIN_PEER_PROTO_VERSION)
+        {
+            // disconnect from peers older than this proto version
+            LogPrintf("peer=%d using obsolete version %i; disconnecting\n", pfrom->id, pfrom->nVersion);
+            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 (pfrom->nVersion == 10300)
+            pfrom->nVersion = 300;
+        if (!vRecv.empty())
+            vRecv >> addrFrom >> nNonce;
+        if (!vRecv.empty()) {
+            vRecv >> LIMITED_STRING(pfrom->strSubVer, MAX_SUBVERSION_LENGTH);
+            pfrom->cleanSubVer = SanitizeString(pfrom->strSubVer);
+        }
+        if (!vRecv.empty()) {
+            vRecv >> pfrom->nStartingHeight;
+        }
+        {
+            LOCK(pfrom->cs_filter);
+            if (!vRecv.empty())
+                vRecv >> pfrom->fRelayTxes; // set to true after we get the first filter* message
+            else
+                pfrom->fRelayTxes = 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;
+        }
+
+        pfrom->addrLocal = addrMe;
+        if (pfrom->fInbound && addrMe.IsRoutable())
+        {
+            SeenLocal(addrMe);
+        }
+
+        // Be shy and don't send version until we hear
+        if (pfrom->fInbound)
+            PushNodeVersion(pfrom, connman, GetAdjustedTime());
+
+        pfrom->fClient = !(pfrom->nServices & NODE_NETWORK);
+
+        if((pfrom->nServices & NODE_WITNESS))
+        {
+            LOCK(cs_main);
+            State(pfrom->GetId())->fHaveWitness = true;
+        }
+
+        // Potentially mark this peer as a preferred download peer.
+        {
+        LOCK(cs_main);
+        UpdatePreferredDownload(pfrom, State(pfrom->GetId()));
+        }
+
+        // Change version
+        connman.PushMessage(pfrom, CNetMsgMaker(INIT_PROTO_VERSION).Make(NetMsgType::VERACK));
+        int nSendVersion = std::min(pfrom->nVersion, PROTOCOL_VERSION);
+        pfrom->SetSendVersion(nSendVersion);
+
+        if (!pfrom->fInbound)
+        {
+            // Advertise our address
+            if (fListen && !IsInitialBlockDownload())
+            {
+                CAddress addr = GetLocalAddress(&pfrom->addr, pfrom->GetLocalServices());
+                FastRandomContext insecure_rand;
+                if (addr.IsRoutable())
+                {
+                    LogPrint("net", "ProcessMessages: advertising address %s\n", addr.ToString());
+                    pfrom->PushAddress(addr, insecure_rand);
+                } else if (IsPeerAddrLocalGood(pfrom)) {
+                    addr.SetIP(pfrom->addrLocal);
+                    LogPrint("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);
+        }
+
+        pfrom->fSuccessfullyConnected = true;
+
+        string remoteAddr;
+        if (fLogIPs)
+            remoteAddr = ", peeraddr=" + pfrom->addr.ToString();
+
+        LogPrintf("receive version message: %s: version %d, blocks=%d, us=%s, peer=%d%s\n",
+                  pfrom->cleanSubVer, pfrom->nVersion,
+                  pfrom->nStartingHeight, addrMe.ToString(), pfrom->id,
+                  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;
+    }
+
+
+    else 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.
+    CNetMsgMaker msgMaker(pfrom->GetSendVersion());
+
+    if (strCommand == NetMsgType::VERACK)
+    {
+        pfrom->SetRecvVersion(min(pfrom->nVersion, 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;
+        }
+
+        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) {
+            // Tell our peer we are willing to provide version 1 or 2 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 = 2;
+            if (pfrom->GetLocalServices() & NODE_WITNESS)
+                connman.PushMessage(pfrom, msgMaker.Make(NetMsgType::SENDCMPCT, fAnnounceUsingCMPCTBLOCK, nCMPCTBLOCKVersion));
+            nCMPCTBLOCKVersion = 1;
+            connman.PushMessage(pfrom, msgMaker.Make(NetMsgType::SENDCMPCT, fAnnounceUsingCMPCTBLOCK, nCMPCTBLOCKVersion));
+        }
+    }
+
+
+    else if (strCommand == NetMsgType::ADDR)
+    {
+        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);
+            return error("message addr size() = %u", vAddr.size());
+        }
+
+        // Store the new addresses
+        vector<CAddress> vAddrOk;
+        int64_t nNow = GetAdjustedTime();
+        int64_t nSince = nNow - 10 * 60;
+        BOOST_FOREACH(CAddress& addr, vAddr)
+        {
+            boost::this_thread::interruption_point();
+
+            if ((addr.nServices & REQUIRED_SERVICES) != REQUIRED_SERVICES)
+                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())
+            {
+                // Relay to a limited number of other nodes
+                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;
+    }
+
+    else if (strCommand == NetMsgType::SENDHEADERS)
+    {
+        LOCK(cs_main);
+        State(pfrom->GetId())->fPreferHeaders = true;
+    }
+
+    else if (strCommand == NetMsgType::SENDCMPCT)
+    {
+        bool fAnnounceUsingCMPCTBLOCK = false;
+        uint64_t nCMPCTBLOCKVersion = 0;
+        vRecv >> fAnnounceUsingCMPCTBLOCK >> nCMPCTBLOCKVersion;
+        if (nCMPCTBLOCKVersion == 1 || ((pfrom->GetLocalServices() & NODE_WITNESS) && nCMPCTBLOCKVersion == 2)) {
+            LOCK(cs_main);
+            // fProvidesHeaderAndIDs is used to "lock in" version of compact blocks we send (fWantsCmpctWitness)
+            if (!State(pfrom->GetId())->fProvidesHeaderAndIDs) {
+                State(pfrom->GetId())->fProvidesHeaderAndIDs = true;
+                State(pfrom->GetId())->fWantsCmpctWitness = nCMPCTBLOCKVersion == 2;
+            }
+            if (State(pfrom->GetId())->fWantsCmpctWitness == (nCMPCTBLOCKVersion == 2)) // ignore later version announces
+                State(pfrom->GetId())->fPreferHeaderAndIDs = fAnnounceUsingCMPCTBLOCK;
+            if (!State(pfrom->GetId())->fSupportsDesiredCmpctVersion) {
+                if (pfrom->GetLocalServices() & NODE_WITNESS)
+                    State(pfrom->GetId())->fSupportsDesiredCmpctVersion = (nCMPCTBLOCKVersion == 2);
+                else
+                    State(pfrom->GetId())->fSupportsDesiredCmpctVersion = (nCMPCTBLOCKVersion == 1);
+            }
+        }
+    }
+
+
+    else if (strCommand == NetMsgType::INV)
+    {
+        vector<CInv> vInv;
+        vRecv >> vInv;
+        if (vInv.size() > MAX_INV_SZ)
+        {
+            LOCK(cs_main);
+            Misbehaving(pfrom->GetId(), 20);
+            return error("message inv size() = %u", vInv.size());
+        }
+
+        bool fBlocksOnly = !fRelayTxes;
+
+        // Allow whitelisted peers to send data other than blocks in blocks only mode if whitelistrelay is true
+        if (pfrom->fWhitelisted && GetBoolArg("-whitelistrelay", DEFAULT_WHITELISTRELAY))
+            fBlocksOnly = false;
+
+        LOCK(cs_main);
+
+        uint32_t nFetchFlags = GetFetchFlags(pfrom, chainActive.Tip(), chainparams.GetConsensus());
+
+        std::vector<CInv> vToFetch;
+
+        for (unsigned int nInv = 0; nInv < vInv.size(); nInv++)
+        {
+            CInv &inv = vInv[nInv];
+
+            boost::this_thread::interruption_point();
+
+            bool fAlreadyHave = AlreadyHave(inv);
+            LogPrint("net", "got inv: %s  %s peer=%d\n", inv.ToString(), fAlreadyHave ? "have" : "new", pfrom->id);
+
+            if (inv.type == MSG_TX) {
+                inv.type |= nFetchFlags;
+            }
+
+            if (inv.type == MSG_BLOCK) {
+                UpdateBlockAvailability(pfrom->GetId(), inv.hash);
+                if (!fAlreadyHave && !fImporting && !fReindex && !mapBlocksInFlight.count(inv.hash)) {
+                    // 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("net", "getheaders (%d) %s to peer=%d\n", pindexBestHeader->nHeight, inv.hash.ToString(), pfrom->id);
+                }
+            }
+            else
+            {
+                pfrom->AddInventoryKnown(inv);
+                if (fBlocksOnly)
+                    LogPrint("net", "transaction (%s) inv sent in violation of protocol peer=%d\n", inv.hash.ToString(), pfrom->id);
+                else if (!fAlreadyHave && !fImporting && !fReindex && !IsInitialBlockDownload())
+                    pfrom->AskFor(inv);
+            }
+
+            // Track requests for our stuff
+            GetMainSignals().Inventory(inv.hash);
+
+            if (pfrom->nSendSize > (nMaxSendBufferSize * 2)) {
+                Misbehaving(pfrom->GetId(), 50);
+                return error("send buffer size() = %u", pfrom->nSendSize);
+            }
+        }
+
+        if (!vToFetch.empty())
+            connman.PushMessage(pfrom, msgMaker.Make(NetMsgType::GETDATA, vToFetch));
+    }
+
+
+    else if (strCommand == NetMsgType::GETDATA)
+    {
+        vector<CInv> vInv;
+        vRecv >> vInv;
+        if (vInv.size() > MAX_INV_SZ)
+        {
+            LOCK(cs_main);
+            Misbehaving(pfrom->GetId(), 20);
+            return error("message getdata size() = %u", vInv.size());
+        }
+
+        if (fDebug || (vInv.size() != 1))
+            LogPrint("net", "received getdata (%u invsz) peer=%d\n", vInv.size(), pfrom->id);
+
+        if ((fDebug && vInv.size() > 0) || (vInv.size() == 1))
+            LogPrint("net", "received getdata for: %s peer=%d\n", vInv[0].ToString(), pfrom->id);
+
+        pfrom->vRecvGetData.insert(pfrom->vRecvGetData.end(), vInv.begin(), vInv.end());
+        ProcessGetData(pfrom, chainparams.GetConsensus(), connman);
+    }
+
+
+    else if (strCommand == NetMsgType::GETBLOCKS)
+    {
+        CBlockLocator locator;
+        uint256 hashStop;
+        vRecv >> locator >> hashStop;
+
+        LOCK(cs_main);
+
+        // Find the last block the caller has in the main chain
+        CBlockIndex* pindex = FindForkInGlobalIndex(chainActive, locator);
+
+        // Send the rest of the chain
+        if (pindex)
+            pindex = chainActive.Next(pindex);
+        int nLimit = 500;
+        LogPrint("net", "getblocks %d to %s limit %d from peer=%d\n", (pindex ? pindex->nHeight : -1), hashStop.IsNull() ? "end" : hashStop.ToString(), nLimit, pfrom->id);
+        for (; pindex; pindex = chainActive.Next(pindex))
+        {
+            if (pindex->GetBlockHash() == hashStop)
+            {
+                LogPrint("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("net", " getblocks stopping, pruned or too old block at %d %s\n", pindex->nHeight, pindex->GetBlockHash().ToString());
+                break;
+            }
+            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("net", "  getblocks stopping at limit %d %s\n", pindex->nHeight, pindex->GetBlockHash().ToString());
+                pfrom->hashContinue = pindex->GetBlockHash();
+                break;
+            }
+        }
+    }
+
+
+    else if (strCommand == NetMsgType::GETBLOCKTXN)
+    {
+        BlockTransactionsRequest req;
+        vRecv >> req;
+
+        LOCK(cs_main);
+
+        BlockMap::iterator it = mapBlockIndex.find(req.blockhash);
+        if (it == mapBlockIndex.end() || !(it->second->nStatus & BLOCK_HAVE_DATA)) {
+            LogPrintf("Peer %d sent us a getblocktxn for a block we don't have", pfrom->id);
+            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("net", "Peer %d sent us a getblocktxn for a block > %i deep", pfrom->id, MAX_BLOCKTXN_DEPTH);
+            CInv inv;
+            inv.type = State(pfrom->GetId())->fWantsCmpctWitness ? MSG_WITNESS_BLOCK : MSG_BLOCK;
+            inv.hash = req.blockhash;
+            pfrom->vRecvGetData.push_back(inv);
+            ProcessGetData(pfrom, chainparams.GetConsensus(), connman);
+            return true;
+        }
+
+        CBlock block;
+        assert(ReadBlockFromDisk(block, it->second, chainparams.GetConsensus()));
+
+        BlockTransactions resp(req);
+        for (size_t i = 0; i < req.indexes.size(); i++) {
+            if (req.indexes[i] >= block.vtx.size()) {
+                Misbehaving(pfrom->GetId(), 100);
+                LogPrintf("Peer %d sent us a getblocktxn with out-of-bounds tx indices", pfrom->id);
+                return true;
+            }
+            resp.txn[i] = block.vtx[req.indexes[i]];
+        }
+        int nSendFlags = State(pfrom->GetId())->fWantsCmpctWitness ? 0 : SERIALIZE_TRANSACTION_NO_WITNESS;
+        connman.PushMessage(pfrom, msgMaker.Make(nSendFlags, NetMsgType::BLOCKTXN, resp));
+    }
+
+
+    else if (strCommand == NetMsgType::GETHEADERS)
+    {
+        CBlockLocator locator;
+        uint256 hashStop;
+        vRecv >> locator >> hashStop;
+
+        LOCK(cs_main);
+        if (IsInitialBlockDownload() && !pfrom->fWhitelisted) {
+            LogPrint("net", "Ignoring getheaders from peer=%d because node is in initial block download\n", pfrom->id);
+            return true;
+        }
+
+        CNodeState *nodestate = State(pfrom->GetId());
+        CBlockIndex* pindex = NULL;
+        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;
+        }
+        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
+        vector<CBlock> vHeaders;
+        int nLimit = MAX_HEADERS_RESULTS;
+        LogPrint("net", "getheaders %d to %s from peer=%d\n", (pindex ? pindex->nHeight : -1), hashStop.IsNull() ? "end" : hashStop.ToString(), pfrom->id);
+        for (; pindex; pindex = chainActive.Next(pindex))
+        {
+            vHeaders.push_back(pindex->GetBlockHeader());
+            if (--nLimit <= 0 || pindex->GetBlockHash() == hashStop)
+                break;
+        }
+        // pindex can be NULL 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.
+        nodestate->pindexBestHeaderSent = pindex ? pindex : chainActive.Tip();
+        connman.PushMessage(pfrom, msgMaker.Make(NetMsgType::HEADERS, vHeaders));
+    }
+
+
+    else if (strCommand == NetMsgType::TX)
+    {
+        // 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 || !GetBoolArg("-whitelistrelay", DEFAULT_WHITELISTRELAY)))
+        {
+            LogPrint("net", "transaction sent in violation of protocol peer=%d\n", pfrom->id);
+            return true;
+        }
+
+        deque<COutPoint> vWorkQueue;
+        vector<uint256> vEraseQueue;
+        CTransaction tx;
+        vRecv >> tx;
+
+        CInv inv(MSG_TX, tx.GetHash());
+        pfrom->AddInventoryKnown(inv);
+
+        LOCK(cs_main);
+
+        bool fMissingInputs = false;
+        CValidationState state;
+
+        pfrom->setAskFor.erase(inv.hash);
+        mapAlreadyAskedFor.erase(inv.hash);
+
+        if (!AlreadyHave(inv) && AcceptToMemoryPool(mempool, state, tx, true, &fMissingInputs)) {
+            mempool.check(pcoinsTip);
+            RelayTransaction(tx, connman);
+            for (unsigned int i = 0; i < tx.vout.size(); i++) {
+                vWorkQueue.emplace_back(inv.hash, i);
+            }
+
+            pfrom->nLastTXTime = GetTime();
+
+            LogPrint("mempool", "AcceptToMemoryPool: peer=%d: accepted %s (poolsz %u txn, %u kB)\n",
+                pfrom->id,
+                tx.GetHash().ToString(),
+                mempool.size(), mempool.DynamicMemoryUsage() / 1000);
+
+            // Recursively process any orphan transactions that depended on this one
+            set<NodeId> setMisbehaving;
+            while (!vWorkQueue.empty()) {
+                auto itByPrev = mapOrphanTransactionsByPrev.find(vWorkQueue.front());
+                vWorkQueue.pop_front();
+                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();
+                    NodeId fromPeer = (*mi)->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, orphanTx, true, &fMissingInputs2)) {
+                        LogPrint("mempool", "   accepted orphan tx %s\n", orphanHash.ToString());
+                        RelayTransaction(orphanTx, connman);
+                        for (unsigned int i = 0; i < orphanTx.vout.size(); i++) {
+                            vWorkQueue.emplace_back(orphanHash, i);
+                        }
+                        vEraseQueue.push_back(orphanHash);
+                    }
+                    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("mempool", "   invalid orphan tx %s\n", orphanHash.ToString());
+                        }
+                        // Has inputs but not accepted to mempool
+                        // Probably non-standard or insufficient fee/priority
+                        LogPrint("mempool", "   removed orphan tx %s\n", orphanHash.ToString());
+                        vEraseQueue.push_back(orphanHash);
+                        if (orphanTx.wit.IsNull() && !stateDummy.CorruptionPossible()) {
+                            // Do not use rejection cache for witness transactions or
+                            // witness-stripped transactions, as they can have been malleated.
+                            // See https://github.com/bitcoin/bitcoin/issues/8279 for details.
+                            assert(recentRejects);
+                            recentRejects->insert(orphanHash);
+                        }
+                    }
+                    mempool.check(pcoinsTip);
+                }
+            }
+
+            BOOST_FOREACH(uint256 hash, vEraseQueue)
+                EraseOrphanTx(hash);
+        }
+        else if (fMissingInputs)
+        {
+            bool fRejectedParents = false; // It may be the case that the orphans parents have all been rejected
+            BOOST_FOREACH(const CTxIn& txin, tx.vin) {
+                if (recentRejects->contains(txin.prevout.hash)) {
+                    fRejectedParents = true;
+                    break;
+                }
+            }
+            if (!fRejectedParents) {
+                uint32_t nFetchFlags = GetFetchFlags(pfrom, chainActive.Tip(), chainparams.GetConsensus());
+                BOOST_FOREACH(const CTxIn& txin, tx.vin) {
+                    CInv _inv(MSG_TX | nFetchFlags, txin.prevout.hash);
+                    pfrom->AddInventoryKnown(_inv);
+                    if (!AlreadyHave(_inv)) pfrom->AskFor(_inv);
+                }
+                AddOrphanTx(tx, pfrom->GetId());
+
+                // DoS prevention: do not allow mapOrphanTransactions to grow unbounded
+                unsigned int nMaxOrphanTx = (unsigned int)std::max((int64_t)0, GetArg("-maxorphantx", DEFAULT_MAX_ORPHAN_TRANSACTIONS));
+                unsigned int nEvicted = LimitOrphanTxSize(nMaxOrphanTx);
+                if (nEvicted > 0)
+                    LogPrint("mempool", "mapOrphan overflow, removed %u tx\n", nEvicted);
+            } else {
+                LogPrint("mempool", "not keeping orphan with rejected parents %s\n",tx.GetHash().ToString());
+            }
+        } else {
+            if (tx.wit.IsNull() && !state.CorruptionPossible()) {
+                // Do not use rejection cache for witness transactions or
+                // witness-stripped transactions, as they can have been malleated.
+                // See https://github.com/bitcoin/bitcoin/issues/8279 for details.
+                assert(recentRejects);
+                recentRejects->insert(tx.GetHash());
+            }
+
+            if (pfrom->fWhitelisted && 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->id);
+                    RelayTransaction(tx, connman);
+                } else {
+                    LogPrintf("Not relaying invalid transaction %s from whitelisted peer=%d (%s)\n", tx.GetHash().ToString(), pfrom->id, FormatStateMessage(state));
+                }
+            }
+        }
+        int nDoS = 0;
+        if (state.IsInvalid(nDoS))
+        {
+            LogPrint("mempoolrej", "%s from peer=%d was not accepted: %s\n", tx.GetHash().ToString(),
+                pfrom->id,
+                FormatStateMessage(state));
+            if (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);
+            }
+        }
+    }
+
+
+    else if (strCommand == NetMsgType::CMPCTBLOCK && !fImporting && !fReindex) // Ignore blocks received while importing
+    {
+        CBlockHeaderAndShortTxIDs cmpctblock;
+        vRecv >> cmpctblock;
+
+        {
+        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;
+        }
+        }
+
+        CBlockIndex *pindex = NULL;
+        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);
+                }
+                LogPrintf("Peer %d sent us invalid header via cmpctblock\n", pfrom->id);
+                return true;
+            }
+        }
+
+        LOCK(cs_main);
+        // If AcceptBlockHeader returned true, it set pindex
+        assert(pindex);
+        UpdateBlockAvailability(pfrom->GetId(), pindex->GetBlockHash());
+
+        std::map<uint256, pair<NodeId, 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 | GetFetchFlags(pfrom, pindex->pprev, chainparams.GetConsensus()), 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;
+
+        CNodeState *nodestate = State(pfrom->GetId());
+
+        if (IsWitnessEnabled(pindex->pprev, chainparams.GetConsensus()) && !nodestate->fSupportsDesiredCmpctVersion) {
+            // Don't bother trying to process compact blocks from v1 peers
+            // after segwit activates.
+            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())) {
+                list<QueuedBlock>::iterator *queuedBlockIt = NULL;
+                if (!MarkBlockAsInFlight(pfrom->GetId(), pindex->GetBlockHash(), chainparams.GetConsensus(), 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("net", "Peer sent us compact block we were already syncing!\n");
+                        return true;
+                    }
+                }
+
+                PartiallyDownloadedBlock& partialBlock = *(*queuedBlockIt)->partialBlock;
+                ReadStatus status = partialBlock.InitData(cmpctblock);
+                if (status == READ_STATUS_INVALID) {
+                    MarkBlockAsReceived(pindex->GetBlockHash()); // Reset in-flight state in case of whitelist
+                    Misbehaving(pfrom->GetId(), 100);
+                    LogPrintf("Peer %d sent us invalid compact block\n", pfrom->id);
+                    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 | GetFetchFlags(pfrom, pindex->pprev, chainparams.GetConsensus()), cmpctblock.header.GetHash());
+                    connman.PushMessage(pfrom, msgMaker.Make(NetMsgType::GETDATA, vInv));
+                    return true;
+                }
+
+                if (!fAlreadyInFlight && mapBlocksInFlight.size() == 1 && pindex->pprev->IsValid(BLOCK_VALID_CHAIN)) {
+                    // We seem to be rather well-synced, so it appears pfrom was the first to provide us
+                    // with this block! Let's get them to announce using compact blocks in the future.
+                    MaybeSetPeerAsAnnouncingHeaderAndIDs(nodestate, pfrom, connman);
+                }
+
+                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();
+                    CDataStream blockTxnMsg(SER_NETWORK, PROTOCOL_VERSION);
+                    blockTxnMsg << txn;
+                    return ProcessMessage(pfrom, NetMsgType::BLOCKTXN, blockTxnMsg, nTimeReceived, chainparams, connman);
+                } else {
+                    req.blockhash = pindex->GetBlockHash();
+                    connman.PushMessage(pfrom, msgMaker.Make(NetMsgType::GETBLOCKTXN, req));
+                }
+            }
+        } 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 | GetFetchFlags(pfrom, pindex->pprev, chainparams.GetConsensus()), 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
+                // Dirty hack to process as if it were just a headers message (TODO: move message handling into their own functions)
+                std::vector<CBlock> headers;
+                headers.push_back(cmpctblock.header);
+                CDataStream vHeadersMsg(SER_NETWORK, PROTOCOL_VERSION);
+                vHeadersMsg << headers;
+                return ProcessMessage(pfrom, NetMsgType::HEADERS, vHeadersMsg, nTimeReceived, chainparams, connman);
+            }
+        }
+    }
+
+    else if (strCommand == NetMsgType::BLOCKTXN && !fImporting && !fReindex) // Ignore blocks received while importing
+    {
+        BlockTransactions resp;
+        vRecv >> resp;
+
+        CBlock block;
+        bool fBlockRead = false;
+        {
+            LOCK(cs_main);
+
+            map<uint256, pair<NodeId, list<QueuedBlock>::iterator> >::iterator it = mapBlocksInFlight.find(resp.blockhash);
+            if (it == mapBlocksInFlight.end() || !it->second.second->partialBlock ||
+                    it->second.first != pfrom->GetId()) {
+                LogPrint("net", "Peer %d sent us block transactions for block we weren't expecting\n", pfrom->id);
+                return true;
+            }
+
+            PartiallyDownloadedBlock& partialBlock = *it->second.second->partialBlock;
+            ReadStatus status = partialBlock.FillBlock(block, resp.txn);
+            if (status == READ_STATUS_INVALID) {
+                MarkBlockAsReceived(resp.blockhash); // Reset in-flight state in case of whitelist
+                Misbehaving(pfrom->GetId(), 100);
+                LogPrintf("Peer %d sent us invalid compact block/non-matching block transactions\n", pfrom->id);
+                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 | GetFetchFlags(pfrom, chainActive.Tip(), chainparams.GetConsensus()), 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)
+            ProcessNewBlock(chainparams, &block, true, NULL, &fNewBlock);
+            if (fNewBlock)
+                pfrom->nLastBlockTime = GetTime();
+        }
+    }
+
+
+    else 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);
+            return error("headers message size = %u", nCount);
+        }
+        headers.resize(nCount);
+        for (unsigned int n = 0; n < nCount; n++) {
+            vRecv >> headers[n];
+            ReadCompactSize(vRecv); // ignore tx count; assume it is 0.
+        }
+
+        if (nCount == 0) {
+            // Nothing interesting. Stop asking this peers for more headers.
+            return true;
+        }
+
+        CBlockIndex *pindexLast = NULL;
+        {
+        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("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->id, 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);
+                return error("non-continuous headers sequence");
+            }
+            hashLastBlock = header.GetHash();
+        }
+        }
+
+        CValidationState state;
+        if (!ProcessNewBlockHeaders(headers, state, chainparams, &pindexLast)) {
+            int nDoS;
+            if (state.IsInvalid(nDoS)) {
+                if (nDoS > 0) {
+                    LOCK(cs_main);
+                    Misbehaving(pfrom->GetId(), nDoS);
+                }
+                return error("invalid header received");
+            }
+        }
+
+        {
+        LOCK(cs_main);
+        CNodeState *nodestate = State(pfrom->GetId());
+        if (nodestate->nUnconnectingHeaders > 0) {
+            LogPrint("net", "peer=%d: resetting nUnconnectingHeaders (%d -> 0)\n", pfrom->id, nodestate->nUnconnectingHeaders);
+        }
+        nodestate->nUnconnectingHeaders = 0;
+
+        assert(pindexLast);
+        UpdateBlockAvailability(pfrom->GetId(), pindexLast->GetBlockHash());
+
+        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("net", "more getheaders (%d) to end to peer=%d (startheight:%d)\n", pindexLast->nHeight, pfrom->id, 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) {
+            vector<CBlockIndex *> vToFetch;
+            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()) &&
+                        (!IsWitnessEnabled(pindexWalk->pprev, chainparams.GetConsensus()) || State(pfrom->GetId())->fHaveWitness)) {
+                    // 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("net", "Large reorg, won't direct fetch to %s (%d)\n",
+                        pindexLast->GetBlockHash().ToString(),
+                        pindexLast->nHeight);
+            } else {
+                vector<CInv> vGetData;
+                // Download as much as possible, from earliest to latest.
+                BOOST_REVERSE_FOREACH(CBlockIndex *pindex, vToFetch) {
+                    if (nodestate->nBlocksInFlight >= MAX_BLOCKS_IN_TRANSIT_PER_PEER) {
+                        // Can't download any more from this peer
+                        break;
+                    }
+                    uint32_t nFetchFlags = GetFetchFlags(pfrom, pindex->pprev, chainparams.GetConsensus());
+                    vGetData.push_back(CInv(MSG_BLOCK | nFetchFlags, pindex->GetBlockHash()));
+                    MarkBlockAsInFlight(pfrom->GetId(), pindex->GetBlockHash(), chainparams.GetConsensus(), pindex);
+                    LogPrint("net", "Requesting block %s from  peer=%d\n",
+                            pindex->GetBlockHash().ToString(), pfrom->id);
+                }
+                if (vGetData.size() > 1) {
+                    LogPrint("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)) {
+                        // We seem to be rather well-synced, so it appears pfrom was the first to provide us
+                        // with this block! Let's get them to announce using compact blocks in the future.
+                        MaybeSetPeerAsAnnouncingHeaderAndIDs(nodestate, pfrom, connman);
+                        // 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));
+                }
+            }
+        }
+        }
+    }
+
+    else if (strCommand == NetMsgType::BLOCK && !fImporting && !fReindex) // Ignore blocks received while importing
+    {
+        CBlock block;
+        vRecv >> block;
+
+        LogPrint("net", "received block %s peer=%d\n", block.GetHash().ToString(), pfrom->id);
+
+        // Process all blocks from whitelisted peers, even if not requested,
+        // unless we're still syncing with the network.
+        // Such an unrequested block may still be processed, subject to the
+        // conditions in AcceptBlock().
+        bool forceProcessing = pfrom->fWhitelisted && !IsInitialBlockDownload();
+        const uint256 hash(block.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, &block, forceProcessing, NULL, &fNewBlock);
+        if (fNewBlock)
+            pfrom->nLastBlockTime = GetTime();
+    }
+
+
+    else 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("net", "Ignoring \"getaddr\" from outbound connection. peer=%d\n", pfrom->id);
+            return true;
+        }
+
+        // Only send one GetAddr response per connection to reduce resource waste
+        //  and discourage addr stamping of INV announcements.
+        if (pfrom->fSentAddr) {
+            LogPrint("net", "Ignoring repeated \"getaddr\". peer=%d\n", pfrom->id);
+            return true;
+        }
+        pfrom->fSentAddr = true;
+
+        pfrom->vAddrToSend.clear();
+        vector<CAddress> vAddr = connman.GetAddresses();
+        FastRandomContext insecure_rand;
+        BOOST_FOREACH(const CAddress &addr, vAddr)
+            pfrom->PushAddress(addr, insecure_rand);
+    }
+
+
+    else if (strCommand == NetMsgType::MEMPOOL)
+    {
+        if (!(pfrom->GetLocalServices() & NODE_BLOOM) && !pfrom->fWhitelisted)
+        {
+            LogPrint("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("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;
+    }
+
+
+    else 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));
+        }
+    }
+
+
+    else 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, 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("net", "pong peer=%d: %s, %x expected, %x received, %u bytes\n",
+                pfrom->id,
+                sProblem,
+                pfrom->nPingNonceSent,
+                nonce,
+                nAvail);
+        }
+        if (bPingFinished) {
+            pfrom->nPingNonceSent = 0;
+        }
+    }
+
+
+    else 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);
+            delete pfrom->pfilter;
+            pfrom->pfilter = new CBloomFilter(filter);
+            pfrom->pfilter->UpdateEmptyFull();
+            pfrom->fRelayTxes = true;
+        }
+    }
+
+
+    else if (strCommand == NetMsgType::FILTERADD)
+    {
+        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);
+        }
+    }
+
+
+    else if (strCommand == NetMsgType::FILTERCLEAR)
+    {
+        LOCK(pfrom->cs_filter);
+        if (pfrom->GetLocalServices() & NODE_BLOOM) {
+            delete pfrom->pfilter;
+            pfrom->pfilter = new CBloomFilter();
+        }
+        pfrom->fRelayTxes = true;
+    }
+
+
+    else if (strCommand == NetMsgType::REJECT)
+    {
+        if (fDebug) {
+            try {
+                string strMsg; unsigned char ccode; string strReason;
+                vRecv >> LIMITED_STRING(strMsg, CMessageHeader::COMMAND_SIZE) >> ccode >> LIMITED_STRING(strReason, MAX_REJECT_MESSAGE_LENGTH);
+
+                ostringstream ss;
+                ss << strMsg << " code " << itostr(ccode) << ": " << strReason;
+
+                if (strMsg == NetMsgType::BLOCK || strMsg == NetMsgType::TX)
+                {
+                    uint256 hash;
+                    vRecv >> hash;
+                    ss << ": hash " << hash.ToString();
+                }
+                LogPrint("net", "Reject %s\n", SanitizeString(ss.str()));
+            } catch (const std::ios_base::failure&) {
+                // Avoid feedback loops by preventing reject messages from triggering a new reject message.
+                LogPrint("net", "Unparseable reject message received\n");
+            }
+        }
+    }
+
+    else if (strCommand == NetMsgType::FEEFILTER) {
+        CAmount newFeeFilter = 0;
+        vRecv >> newFeeFilter;
+        if (MoneyRange(newFeeFilter)) {
+            {
+                LOCK(pfrom->cs_feeFilter);
+                pfrom->minFeeFilter = newFeeFilter;
+            }
+            LogPrint("net", "received: feefilter of %s from peer=%d\n", CFeeRate(newFeeFilter).ToString(), pfrom->id);
+        }
+    }
+
+    else if (strCommand == NetMsgType::NOTFOUND) {
+        // We do not care about the NOTFOUND message, but logging an Unknown Command
+        // message would be undesirable as we transmit it ourselves.
+    }
+
+    else {
+        // Ignore unknown commands for extensibility
+        LogPrint("net", "Unknown command \"%s\" from peer=%d\n", SanitizeString(strCommand), pfrom->id);
+    }
+
+
+
+    return true;
+}
+
+// requires LOCK(cs_vRecvMsg)
+bool ProcessMessages(CNode* pfrom, CConnman& connman)
+{
+    const CChainParams& chainparams = Params();
+    unsigned int nMaxSendBufferSize = connman.GetSendBufferSize();
+    //if (fDebug)
+    //    LogPrintf("%s(%u messages)\n", __func__, pfrom->vRecvMsg.size());
+
+    //
+    // Message format
+    //  (4) message start
+    //  (12) command
+    //  (4) size
+    //  (4) checksum
+    //  (x) data
+    //
+    bool fOk = true;
+
+    if (!pfrom->vRecvGetData.empty())
+        ProcessGetData(pfrom, chainparams.GetConsensus(), connman);
+
+    // this maintains the order of responses
+    if (!pfrom->vRecvGetData.empty()) return fOk;
+
+    std::deque<CNetMessage>::iterator it = pfrom->vRecvMsg.begin();
+    while (!pfrom->fDisconnect && it != pfrom->vRecvMsg.end()) {
+        // Don't bother if send buffer is too full to respond anyway
+        if (pfrom->nSendSize >= nMaxSendBufferSize)
+            break;
+
+        // get next message
+        CNetMessage& msg = *it;
+
+        //if (fDebug)
+        //    LogPrintf("%s(message %u msgsz, %u bytes, complete:%s)\n", __func__,
+        //            msg.hdr.nMessageSize, msg.vRecv.size(),
+        //            msg.complete() ? "Y" : "N");
+
+        // end, if an incomplete message is found
+        if (!msg.complete())
+            break;
+
+        // at this point, any failure means we can delete the current message
+        it++;
+
+        // Scan for message start
+        if (memcmp(msg.hdr.pchMessageStart, chainparams.MessageStart(), CMessageHeader::MESSAGE_START_SIZE) != 0) {
+            LogPrintf("PROCESSMESSAGE: INVALID MESSAGESTART %s peer=%d\n", SanitizeString(msg.hdr.GetCommand()), pfrom->id);
+            fOk = false;
+            break;
+        }
+
+        // Read header
+        CMessageHeader& hdr = msg.hdr;
+        if (!hdr.IsValid(chainparams.MessageStart()))
+        {
+            LogPrintf("PROCESSMESSAGE: ERRORS IN HEADER %s peer=%d\n", SanitizeString(hdr.GetCommand()), pfrom->id);
+            continue;
+        }
+        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)
+        {
+            LogPrintf("%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));
+            continue;
+        }
+
+        // Process message
+        bool fRet = false;
+        try
+        {
+            fRet = ProcessMessage(pfrom, strCommand, vRecv, msg.nTime, chainparams, connman);
+            boost::this_thread::interruption_point();
+        }
+        catch (const std::ios_base::failure& e)
+        {
+            connman.PushMessage(pfrom, CNetMsgMaker(INIT_PROTO_VERSION).Make(NetMsgType::REJECT, strCommand, REJECT_MALFORMED, string("error parsing message")));
+            if (strstr(e.what(), "end of data"))
+            {
+                // Allow exceptions from under-length message on vRecv
+                LogPrintf("%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
+                LogPrintf("%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
+                LogPrintf("%s(%s, %u bytes): Exception '%s' caught\n", __func__, SanitizeString(strCommand), nMessageSize, e.what());
+            }
+            else
+            {
+                PrintExceptionContinue(&e, "ProcessMessages()");
+            }
+        }
+        catch (const boost::thread_interrupted&) {
+            throw;
+        }
+        catch (const std::exception& e) {
+            PrintExceptionContinue(&e, "ProcessMessages()");
+        } catch (...) {
+            PrintExceptionContinue(NULL, "ProcessMessages()");
+        }
+
+        if (!fRet)
+            LogPrintf("%s(%s, %u bytes) FAILED peer=%d\n", __func__, SanitizeString(strCommand), nMessageSize, pfrom->id);
+
+        break;
+    }
+
+    // In case the connection got shut down, its receive buffer was wiped
+    if (!pfrom->fDisconnect)
+        pfrom->vRecvMsg.erase(pfrom->vRecvMsg.begin(), it);
+
+    return fOk;
+}
+
+class CompareInvMempoolOrder
+{
+    CTxMemPool *mp;
+public:
+    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 SendMessages(CNode* pto, CConnman& connman)
+{
+    const Consensus::Params& consensusParams = Params().GetConsensus();
+    {
+        // Don't send anything until we get its version message
+        if (pto->nVersion == 0 || pto->fDisconnect)
+            return true;
+
+        // If we get here, the outgoing message serialization version is set and can't change.
+        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;
+
+        CNodeState &state = *State(pto->GetId());
+
+        BOOST_FOREACH(const CBlockReject& reject, state.rejects)
+            connman.PushMessage(pto, msgMaker.Make(NetMsgType::REJECT, (string)NetMsgType::BLOCK, reject.chRejectCode, reject.strRejectReason, reject.hashBlock));
+        state.rejects.clear();
+
+        if (state.fShouldBan) {
+            state.fShouldBan = false;
+            if (pto->fWhitelisted)
+                LogPrintf("Warning: not punishing whitelisted peer %s!\n", pto->addr.ToString());
+            else {
+                pto->fDisconnect = true;
+                if (pto->addr.IsLocal())
+                    LogPrintf("Warning: not banning local peer %s!\n", pto->addr.ToString());
+                else
+                {
+                    connman.Ban(pto->addr, BanReasonNodeMisbehaving);
+                }
+                return true;
+            }
+        }
+
+        // Address refresh broadcast
+        int64_t nNow = GetTimeMicros();
+        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);
+            vector<CAddress> vAddr;
+            vAddr.reserve(pto->vAddrToSend.size());
+            BOOST_FOREACH(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 == NULL)
+            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) {
+            // Only actively request headers from a single peer, unless we're close to today.
+            if ((nSyncStarted == 0 && fFetch) || pindexBestHeader->GetBlockTime() > GetAdjustedTime() - 24 * 60 * 60) {
+                state.fSyncStarted = true;
+                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("net", "initial getheaders (%d) to peer=%d (startheight:%d)\n", pindexStart->nHeight, pto->id, 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())
+        {
+            GetMainSignals().Broadcast(nTimeBestReceived, &connman);
+        }
+
+        //
+        // Try sending block announcements via headers
+        //
+        {
+            // 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);
+            vector<CBlock> vHeaders;
+            bool fRevertToInv = ((!state.fPreferHeaders &&
+                                 (!state.fPreferHeaderAndIDs || pto->vBlockHashesToAnnounce.size() > 1)) ||
+                                pto->vBlockHashesToAnnounce.size() > MAX_BLOCKS_TO_ANNOUNCE);
+            CBlockIndex *pBestIndex = NULL; // last header queued for delivery
+            ProcessBlockAvailability(pto->id); // 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.
+                BOOST_FOREACH(const uint256 &hash, pto->vBlockHashesToAnnounce) {
+                    BlockMap::iterator mi = mapBlockIndex.find(hash);
+                    assert(mi != mapBlockIndex.end());
+                    CBlockIndex *pindex = mi->second;
+                    if (chainActive[pindex->nHeight] != pindex) {
+                        // Bail out if we reorged away from this block
+                        fRevertToInv = true;
+                        break;
+                    }
+                    if (pBestIndex != NULL && 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;
+                    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 == NULL || PeerHasHeader(&state, pindex->pprev)) {
+                        // 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("net", "%s sending header-and-ids %s to peer %d\n", __func__,
+                            vHeaders.front().GetHash().ToString(), pto->id);
+                    //TODO: Shouldn't need to reload block from disk, but requires refactor
+                    CBlock block;
+                    assert(ReadBlockFromDisk(block, pBestIndex, consensusParams));
+                    CBlockHeaderAndShortTxIDs cmpctblock(block, state.fWantsCmpctWitness);
+                    int nSendFlags = state.fWantsCmpctWitness ? 0 : SERIALIZE_TRANSACTION_NO_WITNESS;
+                    connman.PushMessage(pto, msgMaker.Make(nSendFlags, NetMsgType::CMPCTBLOCK, cmpctblock));
+                    state.pindexBestHeaderSent = pBestIndex;
+                } else if (state.fPreferHeaders) {
+                    if (vHeaders.size() > 1) {
+                        LogPrint("net", "%s: %u headers, range (%s, %s), to peer=%d\n", __func__,
+                                vHeaders.size(),
+                                vHeaders.front().GetHash().ToString(),
+                                vHeaders.back().GetHash().ToString(), pto->id);
+                    } else {
+                        LogPrint("net", "%s: sending header %s to peer=%d\n", __func__,
+                                vHeaders.front().GetHash().ToString(), pto->id);
+                    }
+                    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());
+                    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("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("net", "%s: sending inv peer=%d hash=%s\n", __func__,
+                            pto->id, hashToAnnounce.ToString());
+                    }
+                }
+            }
+            pto->vBlockHashesToAnnounce.clear();
+        }
+
+        //
+        // Message: inventory
+        //
+        vector<CInv> vInv;
+        {
+            LOCK(pto->cs_inventory);
+            vInv.reserve(std::max<size_t>(pto->vInventoryBlockToSend.size(), INVENTORY_BROADCAST_MAX));
+
+            // Add blocks
+            BOOST_FOREACH(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
+            bool fSendTrickle = pto->fWhitelisted;
+            if (pto->nNextInvSend < nNow) {
+                fSendTrickle = true;
+                // Use half the delay for outbound peers, as there is less privacy concern for them.
+                pto->nNextInvSend = PoissonNextSend(nNow, INVENTORY_BROADCAST_INTERVAL >> !pto->fInbound);
+            }
+
+            // 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;
+                CAmount filterrate = 0;
+                {
+                    LOCK(pto->cs_feeFilter);
+                    filterrate = pto->minFeeFilter;
+                }
+
+                LOCK(pto->cs_filter);
+
+                for (const auto& txinfo : vtxinfo) {
+                    const uint256& hash = txinfo.tx->GetHash();
+                    CInv inv(MSG_TX, hash);
+                    pto->setInventoryTxToSend.erase(hash);
+                    if (filterrate) {
+                        if (txinfo.feeRate.GetFeePerK() < filterrate)
+                            continue;
+                    }
+                    if (pto->pfilter) {
+                        if (!pto->pfilter->IsRelevantAndUpdate(*txinfo.tx)) continue;
+                    }
+                    pto->filterInventoryKnown.insert(hash);
+                    vInv.push_back(inv);
+                    if (vInv.size() == MAX_INV_SZ) {
+                        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
+                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);
+                }
+                CAmount filterrate = 0;
+                {
+                    LOCK(pto->cs_feeFilter);
+                    filterrate = pto->minFeeFilter;
+                }
+                // 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) {
+                    // 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 (filterrate && txinfo.feeRate.GetFeePerK() < filterrate) {
+                        continue;
+                    }
+                    if (pto->pfilter && !pto->pfilter->IsRelevantAndUpdate(*txinfo.tx)) continue;
+                    // Send
+                    vInv.push_back(CInv(MSG_TX, 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);
+                }
+            }
+        }
+        if (!vInv.empty())
+            connman.PushMessage(pto, msgMaker.Make(NetMsgType::INV, vInv));
+
+        // Detect whether we're stalling
+        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->id);
+            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->id);
+                pto->fDisconnect = true;
+                return true;
+            }
+        }
+
+        //
+        // Message: getdata (blocks)
+        //
+        vector<CInv> vGetData;
+        if (!pto->fClient && (fFetch || !IsInitialBlockDownload()) && state.nBlocksInFlight < MAX_BLOCKS_IN_TRANSIT_PER_PEER) {
+            vector<CBlockIndex*> vToDownload;
+            NodeId staller = -1;
+            FindNextBlocksToDownload(pto->GetId(), MAX_BLOCKS_IN_TRANSIT_PER_PEER - state.nBlocksInFlight, vToDownload, staller, consensusParams);
+            BOOST_FOREACH(CBlockIndex *pindex, vToDownload) {
+                uint32_t nFetchFlags = GetFetchFlags(pto, pindex->pprev, consensusParams);
+                vGetData.push_back(CInv(MSG_BLOCK | nFetchFlags, pindex->GetBlockHash()));
+                MarkBlockAsInFlight(pto->GetId(), pindex->GetBlockHash(), consensusParams, pindex);
+                LogPrint("net", "Requesting block %s (%d) peer=%d\n", pindex->GetBlockHash().ToString(),
+                    pindex->nHeight, pto->id);
+            }
+            if (state.nBlocksInFlight == 0 && staller != -1) {
+                if (State(staller)->nStallingSince == 0) {
+                    State(staller)->nStallingSince = nNow;
+                    LogPrint("net", "Stall started peer=%d\n", staller);
+                }
+            }
+        }
+
+        //
+        // Message: getdata (non-blocks)
+        //
+        while (!pto->mapAskFor.empty() && (*pto->mapAskFor.begin()).first <= nNow)
+        {
+            const CInv& inv = (*pto->mapAskFor.begin()).second;
+            if (!AlreadyHave(inv))
+            {
+                if (fDebug)
+                    LogPrint("net", "Requesting %s peer=%d\n", inv.ToString(), pto->id);
+                vGetData.push_back(inv);
+                if (vGetData.size() >= 1000)
+                {
+                    connman.PushMessage(pto, msgMaker.Make(NetMsgType::GETDATA, vGetData));
+                    vGetData.clear();
+                }
+            } else {
+                //If we're not going to ask, don't expect a response.
+                pto->setAskFor.erase(inv.hash);
+            }
+            pto->mapAskFor.erase(pto->mapAskFor.begin());
+        }
+        if (!vGetData.empty())
+            connman.PushMessage(pto, msgMaker.Make(NetMsgType::GETDATA, vGetData));
+
+        //
+        // Message: feefilter
+        //
+        // We don't want white listed peers to filter txs to us if we have -whitelistforcerelay
+        if (pto->nVersion >= FEEFILTER_VERSION && GetBoolArg("-feefilter", DEFAULT_FEEFILTER) &&
+            !(pto->fWhitelisted && GetBoolArg("-whitelistforcerelay", DEFAULT_WHITELISTFORCERELAY))) {
+            CAmount currentFilter = mempool.GetMinFee(GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000).GetFeePerK();
+            int64_t timeNow = GetTimeMicros();
+            if (timeNow > pto->nextSendTimeFeeFilter) {
+                static FeeFilterRounder filterRounder(::minRelayTxFee);
+                CAmount filterToSend = filterRounder.round(currentFilter);
+                if (filterToSend != pto->lastSentFeeFilter) {
+                    connman.PushMessage(pto, msgMaker.Make(NetMsgType::FEEFILTER, filterToSend));
+                    pto->lastSentFeeFilter = filterToSend;
+                }
+                pto->nextSendTimeFeeFilter = PoissonNextSend(timeNow, AVG_FEEFILTER_BROADCAST_INTERVAL);
+            }
+            // If the fee filter has changed substantially and it's still more than MAX_FEEFILTER_CHANGE_DELAY
+            // until scheduled broadcast, then move the broadcast to within MAX_FEEFILTER_CHANGE_DELAY.
+            else if (timeNow + MAX_FEEFILTER_CHANGE_DELAY * 1000000 < pto->nextSendTimeFeeFilter &&
+                     (currentFilter < 3 * pto->lastSentFeeFilter / 4 || currentFilter > 4 * pto->lastSentFeeFilter / 3)) {
+                pto->nextSendTimeFeeFilter = timeNow + GetRandInt(MAX_FEEFILTER_CHANGE_DELAY) * 1000000;
+            }
+        }
+    }
+    return true;
+}
+
+class CNetProcessingCleanup
+{
+public:
+    CNetProcessingCleanup() {}
+    ~CNetProcessingCleanup() {
+        // orphan transactions
+        mapOrphanTransactions.clear();
+        mapOrphanTransactionsByPrev.clear();
+    }
+} instance_of_cnetprocessingcleanup;