diff --git a/src/net.cpp b/src/net.cpp
index 705daf503..6f44fa6b3 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -1,3076 +1,3089 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2019 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #if defined(HAVE_CONFIG_H)
 #include <config/bitcoin-config.h>
 #endif
 
 #include <net.h>
 
 #include <banman.h>
 #include <clientversion.h>
 #include <config.h>
 #include <consensus/consensus.h>
 #include <crypto/sha256.h>
 #include <netbase.h>
 #include <random.h>
 #include <scheduler.h>
 #include <ui_interface.h>
 #include <util/strencodings.h>
 #include <util/translation.h>
 
 #ifdef WIN32
 #include <cstring>
 #else
 #include <fcntl.h>
 #endif
 
 #ifdef USE_POLL
 #include <poll.h>
 #endif
 
 #ifdef USE_UPNP
 #include <miniupnpc/miniupnpc.h>
 #include <miniupnpc/upnpcommands.h>
 #include <miniupnpc/upnperrors.h>
 // The minimum supported miniUPnPc API version is set to 10. This keeps
 // compatibility with Ubuntu 16.04 LTS and Debian 8 libminiupnpc-dev packages.
 static_assert(MINIUPNPC_API_VERSION >= 10,
               "miniUPnPc API version >= 10 assumed");
 #endif
 
 #include <unordered_map>
 
 #include <cmath>
 
 // How often to dump addresses to peers.dat
 static constexpr std::chrono::minutes DUMP_PEERS_INTERVAL{15};
 
 /**
  * Number of DNS seeds to query when the number of connections is low.
  */
 static constexpr int DNSSEEDS_TO_QUERY_AT_ONCE = 3;
 
 // We add a random period time (0 to 1 seconds) to feeler connections to prevent
 // synchronization.
 #define FEELER_SLEEP_WINDOW 1
 
 // MSG_NOSIGNAL is not available on some platforms, if it doesn't exist define
 // it as 0
 #if !defined(MSG_NOSIGNAL)
 #define MSG_NOSIGNAL 0
 #endif
 
 // MSG_DONTWAIT is not available on some platforms, if it doesn't exist define
 // it as 0
 #if !defined(MSG_DONTWAIT)
 #define MSG_DONTWAIT 0
 #endif
 
 /** Used to pass flags to the Bind() function */
 enum BindFlags {
     BF_NONE = 0,
     BF_EXPLICIT = (1U << 0),
     BF_REPORT_ERROR = (1U << 1),
 };
 
 // The set of sockets cannot be modified while waiting
 // The sleep time needs to be small to avoid new sockets stalling
 static const uint64_t SELECT_TIMEOUT_MILLISECONDS = 50;
 
 const std::string NET_MESSAGE_COMMAND_OTHER = "*other*";
 
 // SHA256("netgroup")[0:8]
 static const uint64_t RANDOMIZER_ID_NETGROUP = 0x6c0edd8036ef4036ULL;
 // SHA256("localhostnonce")[0:8]
 static const uint64_t RANDOMIZER_ID_LOCALHOSTNONCE = 0xd93e69e2bbfa5735ULL;
 //
 // Global state variables
 //
 bool fDiscover = true;
 bool fListen = true;
 bool g_relay_txes = !DEFAULT_BLOCKSONLY;
 RecursiveMutex cs_mapLocalHost;
 std::map<CNetAddr, LocalServiceInfo> mapLocalHost GUARDED_BY(cs_mapLocalHost);
 static bool vfLimited[NET_MAX] GUARDED_BY(cs_mapLocalHost) = {};
 
 void CConnman::AddOneShot(const std::string &strDest) {
     LOCK(cs_vOneShots);
     vOneShots.push_back(strDest);
 }
 
 unsigned short GetListenPort() {
     return (unsigned short)(gArgs.GetArg("-port", Params().GetDefaultPort()));
 }
 
 // find 'best' local address for a particular peer
 bool GetLocal(CService &addr, const CNetAddr *paddrPeer) {
     if (!fListen) {
         return false;
     }
 
     int nBestScore = -1;
     int nBestReachability = -1;
     {
         LOCK(cs_mapLocalHost);
         for (const auto &entry : mapLocalHost) {
             int nScore = entry.second.nScore;
             int nReachability = entry.first.GetReachabilityFrom(paddrPeer);
             if (nReachability > nBestReachability ||
                 (nReachability == nBestReachability && nScore > nBestScore)) {
                 addr = CService(entry.first, entry.second.nPort);
                 nBestReachability = nReachability;
                 nBestScore = nScore;
             }
         }
     }
     return nBestScore >= 0;
 }
 
 //! Convert the pnSeed6 array into usable address objects.
 static std::vector<CAddress>
 convertSeed6(const std::vector<SeedSpec6> &vSeedsIn) {
     // It'll only connect to one or two seed nodes because once it connects,
     // it'll get a pile of addresses with newer timestamps. Seed nodes are given
     // a random 'last seen time' of between one and two weeks ago.
     const int64_t nOneWeek = 7 * 24 * 60 * 60;
     std::vector<CAddress> vSeedsOut;
     vSeedsOut.reserve(vSeedsIn.size());
     FastRandomContext rng;
     for (const auto &seed_in : vSeedsIn) {
         struct in6_addr ip;
         memcpy(&ip, seed_in.addr, sizeof(ip));
         CAddress addr(CService(ip, seed_in.port),
                       GetDesirableServiceFlags(NODE_NONE));
         addr.nTime = GetTime() - rng.randrange(nOneWeek) - nOneWeek;
         vSeedsOut.push_back(addr);
     }
     return vSeedsOut;
 }
 
 // Get best local address for a particular peer as a CAddress. Otherwise, return
 // the unroutable 0.0.0.0 but filled in with the normal parameters, since the IP
 // may be changed to a useful one by discovery.
 CAddress GetLocalAddress(const CNetAddr *paddrPeer,
                          ServiceFlags nLocalServices) {
     CAddress ret(CService(CNetAddr(), GetListenPort()), nLocalServices);
     CService addr;
     if (GetLocal(addr, paddrPeer)) {
         ret = CAddress(addr, nLocalServices);
     }
     ret.nTime = GetAdjustedTime();
     return ret;
 }
 
 static int GetnScore(const CService &addr) {
     LOCK(cs_mapLocalHost);
     if (mapLocalHost.count(addr) == 0) {
         return 0;
     }
     return mapLocalHost[addr].nScore;
 }
 
 // Is our peer's addrLocal potentially useful as an external IP source?
 bool IsPeerAddrLocalGood(CNode *pnode) {
     CService addrLocal = pnode->GetAddrLocal();
     return fDiscover && pnode->addr.IsRoutable() && addrLocal.IsRoutable() &&
            IsReachable(addrLocal.GetNetwork());
 }
 
 // Pushes our own address to a peer.
 void AdvertiseLocal(CNode *pnode) {
     if (fListen && pnode->fSuccessfullyConnected) {
         CAddress addrLocal =
             GetLocalAddress(&pnode->addr, pnode->GetLocalServices());
         if (gArgs.GetBoolArg("-addrmantest", false)) {
             // use IPv4 loopback during addrmantest
             addrLocal =
                 CAddress(CService(LookupNumeric("127.0.0.1", GetListenPort())),
                          pnode->GetLocalServices());
         }
         // If discovery is enabled, sometimes give our peer the address it
         // tells us that it sees us as in case it has a better idea of our
         // address than we do.
         FastRandomContext rng;
         if (IsPeerAddrLocalGood(pnode) &&
             (!addrLocal.IsRoutable() ||
              rng.randbits((GetnScore(addrLocal) > LOCAL_MANUAL) ? 3 : 1) ==
                  0)) {
             addrLocal.SetIP(pnode->GetAddrLocal());
         }
         if (addrLocal.IsRoutable() || gArgs.GetBoolArg("-addrmantest", false)) {
             LogPrint(BCLog::NET, "AdvertiseLocal: advertising address %s\n",
                      addrLocal.ToString());
             pnode->PushAddress(addrLocal, rng);
         }
     }
 }
 
 // Learn a new local address.
 bool AddLocal(const CService &addr, int nScore) {
     if (!addr.IsRoutable()) {
         return false;
     }
 
     if (!fDiscover && nScore < LOCAL_MANUAL) {
         return false;
     }
 
     if (!IsReachable(addr)) {
         return false;
     }
 
     LogPrintf("AddLocal(%s,%i)\n", addr.ToString(), nScore);
 
     {
         LOCK(cs_mapLocalHost);
         bool fAlready = mapLocalHost.count(addr) > 0;
         LocalServiceInfo &info = mapLocalHost[addr];
         if (!fAlready || nScore >= info.nScore) {
             info.nScore = nScore + (fAlready ? 1 : 0);
             info.nPort = addr.GetPort();
         }
     }
 
     return true;
 }
 
 bool AddLocal(const CNetAddr &addr, int nScore) {
     return AddLocal(CService(addr, GetListenPort()), nScore);
 }
 
 void RemoveLocal(const CService &addr) {
     LOCK(cs_mapLocalHost);
     LogPrintf("RemoveLocal(%s)\n", addr.ToString());
     mapLocalHost.erase(addr);
 }
 
 void SetReachable(enum Network net, bool reachable) {
     if (net == NET_UNROUTABLE || net == NET_INTERNAL) {
         return;
     }
     LOCK(cs_mapLocalHost);
     vfLimited[net] = !reachable;
 }
 
 bool IsReachable(enum Network net) {
     LOCK(cs_mapLocalHost);
     return !vfLimited[net];
 }
 
 bool IsReachable(const CNetAddr &addr) {
     return IsReachable(addr.GetNetwork());
 }
 
 /** vote for a local address */
 bool SeenLocal(const CService &addr) {
     LOCK(cs_mapLocalHost);
     if (mapLocalHost.count(addr) == 0) {
         return false;
     }
     mapLocalHost[addr].nScore++;
     return true;
 }
 
 /** check whether a given address is potentially local */
 bool IsLocal(const CService &addr) {
     LOCK(cs_mapLocalHost);
     return mapLocalHost.count(addr) > 0;
 }
 
 CNode *CConnman::FindNode(const CNetAddr &ip) {
     LOCK(cs_vNodes);
     for (CNode *pnode : vNodes) {
         if (static_cast<CNetAddr>(pnode->addr) == ip) {
             return pnode;
         }
     }
     return nullptr;
 }
 
 CNode *CConnman::FindNode(const CSubNet &subNet) {
     LOCK(cs_vNodes);
     for (CNode *pnode : vNodes) {
         if (subNet.Match(static_cast<CNetAddr>(pnode->addr))) {
             return pnode;
         }
     }
     return nullptr;
 }
 
 CNode *CConnman::FindNode(const std::string &addrName) {
     LOCK(cs_vNodes);
     for (CNode *pnode : vNodes) {
         if (pnode->GetAddrName() == addrName) {
             return pnode;
         }
     }
     return nullptr;
 }
 
 CNode *CConnman::FindNode(const CService &addr) {
     LOCK(cs_vNodes);
     for (CNode *pnode : vNodes) {
         if (static_cast<CService>(pnode->addr) == addr) {
             return pnode;
         }
     }
     return nullptr;
 }
 
 bool CConnman::CheckIncomingNonce(uint64_t nonce) {
     LOCK(cs_vNodes);
     for (const CNode *pnode : vNodes) {
         if (!pnode->fSuccessfullyConnected && !pnode->fInbound &&
             pnode->GetLocalNonce() == nonce) {
             return false;
         }
     }
     return true;
 }
 
 /** Get the bind address for a socket as CAddress */
 static CAddress GetBindAddress(SOCKET sock) {
     CAddress addr_bind;
     struct sockaddr_storage sockaddr_bind;
     socklen_t sockaddr_bind_len = sizeof(sockaddr_bind);
     if (sock != INVALID_SOCKET) {
         if (!getsockname(sock, (struct sockaddr *)&sockaddr_bind,
                          &sockaddr_bind_len)) {
             addr_bind.SetSockAddr((const struct sockaddr *)&sockaddr_bind);
         } else {
             LogPrint(BCLog::NET, "Warning: getsockname failed\n");
         }
     }
     return addr_bind;
 }
 
 CNode *CConnman::ConnectNode(CAddress addrConnect, const char *pszDest,
                              bool fCountFailure, bool manual_connection,
                              bool block_relay_only) {
     if (pszDest == nullptr) {
         if (IsLocal(addrConnect)) {
             return nullptr;
         }
 
         // Look for an existing connection
         CNode *pnode = FindNode(static_cast<CService>(addrConnect));
         if (pnode) {
             LogPrintf("Failed to open new connection, already connected\n");
             return nullptr;
         }
     }
 
     /// debug print
     LogPrint(BCLog::NET, "trying connection %s lastseen=%.1fhrs\n",
              pszDest ? pszDest : addrConnect.ToString(),
              pszDest
                  ? 0.0
                  : (double)(GetAdjustedTime() - addrConnect.nTime) / 3600.0);
 
     // Resolve
     const int default_port = Params().GetDefaultPort();
     if (pszDest) {
         std::vector<CService> resolved;
         if (Lookup(pszDest, resolved, default_port,
                    fNameLookup && !HaveNameProxy(), 256) &&
             !resolved.empty()) {
             addrConnect =
                 CAddress(resolved[GetRand(resolved.size())], NODE_NONE);
             if (!addrConnect.IsValid()) {
                 LogPrint(BCLog::NET,
                          "Resolver returned invalid address %s for %s\n",
                          addrConnect.ToString(), pszDest);
                 return nullptr;
             }
             // It is possible that we already have a connection to the IP/port
             // pszDest resolved to. In that case, drop the connection that was
             // just created, and return the existing CNode instead. Also store
             // the name we used to connect in that CNode, so that future
             // FindNode() calls to that name catch this early.
             LOCK(cs_vNodes);
             CNode *pnode = FindNode(static_cast<CService>(addrConnect));
             if (pnode) {
                 pnode->MaybeSetAddrName(std::string(pszDest));
                 LogPrintf("Failed to open new connection, already connected\n");
                 return nullptr;
             }
         }
     }
 
     // Connect
     bool connected = false;
     SOCKET hSocket = INVALID_SOCKET;
     proxyType proxy;
     if (addrConnect.IsValid()) {
         bool proxyConnectionFailed = false;
 
         if (GetProxy(addrConnect.GetNetwork(), proxy)) {
             hSocket = CreateSocket(proxy.proxy);
             if (hSocket == INVALID_SOCKET) {
                 return nullptr;
             }
             connected = ConnectThroughProxy(
                 proxy, addrConnect.ToStringIP(), addrConnect.GetPort(), hSocket,
                 nConnectTimeout, &proxyConnectionFailed);
         } else {
             // no proxy needed (none set for target network)
             hSocket = CreateSocket(addrConnect);
             if (hSocket == INVALID_SOCKET) {
                 return nullptr;
             }
             connected = ConnectSocketDirectly(
                 addrConnect, hSocket, nConnectTimeout, manual_connection);
         }
         if (!proxyConnectionFailed) {
             // If a connection to the node was attempted, and failure (if any)
             // is not caused by a problem connecting to the proxy, mark this as
             // an attempt.
             addrman.Attempt(addrConnect, fCountFailure);
         }
     } else if (pszDest && GetNameProxy(proxy)) {
         hSocket = CreateSocket(proxy.proxy);
         if (hSocket == INVALID_SOCKET) {
             return nullptr;
         }
         std::string host;
         int port = default_port;
         SplitHostPort(std::string(pszDest), port, host);
         connected = ConnectThroughProxy(proxy, host, port, hSocket,
                                         nConnectTimeout, nullptr);
     }
     if (!connected) {
         CloseSocket(hSocket);
         return nullptr;
     }
 
     // Add node
     NodeId id = GetNewNodeId();
     uint64_t nonce = GetDeterministicRandomizer(RANDOMIZER_ID_LOCALHOSTNONCE)
                          .Write(id)
                          .Finalize();
     CAddress addr_bind = GetBindAddress(hSocket);
     CNode *pnode =
         new CNode(id, nLocalServices, GetBestHeight(), hSocket, addrConnect,
                   CalculateKeyedNetGroup(addrConnect), nonce, addr_bind,
                   pszDest ? pszDest : "", false, block_relay_only);
     pnode->AddRef();
 
     // We're making a new connection, harvest entropy from the time (and our
     // peer count)
     RandAddEvent((uint32_t)id);
 
     return pnode;
 }
 
 void CNode::CloseSocketDisconnect() {
     fDisconnect = true;
     LOCK(cs_hSocket);
     if (hSocket != INVALID_SOCKET) {
         LogPrint(BCLog::NET, "disconnecting peer=%d\n", id);
         CloseSocket(hSocket);
     }
 }
 
 void CConnman::AddWhitelistPermissionFlags(NetPermissionFlags &flags,
                                            const CNetAddr &addr) const {
     for (const auto &subnet : vWhitelistedRange) {
         if (subnet.m_subnet.Match(addr)) {
             NetPermissions::AddFlag(flags, subnet.m_flags);
         }
     }
 }
 
 std::string CNode::GetAddrName() const {
     LOCK(cs_addrName);
     return addrName;
 }
 
 void CNode::MaybeSetAddrName(const std::string &addrNameIn) {
     LOCK(cs_addrName);
     if (addrName.empty()) {
         addrName = addrNameIn;
     }
 }
 
 CService CNode::GetAddrLocal() const {
     LOCK(cs_addrLocal);
     return addrLocal;
 }
 
 void CNode::SetAddrLocal(const CService &addrLocalIn) {
     LOCK(cs_addrLocal);
     if (addrLocal.IsValid()) {
         error("Addr local already set for node: %i. Refusing to change from %s "
               "to %s",
               id, addrLocal.ToString(), addrLocalIn.ToString());
     } else {
         addrLocal = addrLocalIn;
     }
 }
 
 void CNode::copyStats(CNodeStats &stats, const std::vector<bool> &m_asmap) {
     stats.nodeid = this->GetId();
     stats.nServices = nServices;
     stats.addr = addr;
     stats.addrBind = addrBind;
     stats.m_mapped_as = addr.GetMappedAS(m_asmap);
     if (m_tx_relay != nullptr) {
         LOCK(m_tx_relay->cs_filter);
         stats.fRelayTxes = m_tx_relay->fRelayTxes;
     } else {
         stats.fRelayTxes = false;
     }
     stats.nLastSend = nLastSend;
     stats.nLastRecv = nLastRecv;
     stats.nTimeConnected = nTimeConnected;
     stats.nTimeOffset = nTimeOffset;
     stats.addrName = GetAddrName();
     stats.nVersion = nVersion;
     {
         LOCK(cs_SubVer);
         stats.cleanSubVer = cleanSubVer;
     }
     stats.fInbound = fInbound;
     stats.m_manual_connection = m_manual_connection;
     stats.nStartingHeight = nStartingHeight;
     {
         LOCK(cs_vSend);
         stats.mapSendBytesPerMsgCmd = mapSendBytesPerMsgCmd;
         stats.nSendBytes = nSendBytes;
     }
     {
         LOCK(cs_vRecv);
         stats.mapRecvBytesPerMsgCmd = mapRecvBytesPerMsgCmd;
         stats.nRecvBytes = nRecvBytes;
     }
     stats.m_legacyWhitelisted = m_legacyWhitelisted;
     stats.m_permissionFlags = m_permissionFlags;
     if (m_tx_relay != nullptr) {
         LOCK(m_tx_relay->cs_feeFilter);
         stats.minFeeFilter = m_tx_relay->minFeeFilter;
     } else {
         stats.minFeeFilter = Amount::zero();
     }
 
     // It is common for nodes with good ping times to suddenly become lagged,
     // due to a new block arriving or other large transfer. Merely reporting
     // pingtime might fool the caller into thinking the node was still
     // responsive, since pingtime does not update until the ping is complete,
     // which might take a while. So, if a ping is taking an unusually long time
     // in flight, the caller can immediately detect that this is happening.
     int64_t nPingUsecWait = 0;
     if ((0 != nPingNonceSent) && (0 != nPingUsecStart)) {
         nPingUsecWait = GetTimeMicros() - nPingUsecStart;
     }
 
     // Raw ping time is in microseconds, but show it to user as whole seconds
     // (Bitcoin users should be well used to small numbers with many decimal
     // places by now :)
     stats.m_ping_usec = nPingUsecTime;
     stats.m_min_ping_usec = nMinPingUsecTime;
     stats.m_ping_wait_usec = nPingUsecWait;
 
     // Leave string empty if addrLocal invalid (not filled in yet)
     CService addrLocalUnlocked = GetAddrLocal();
     stats.addrLocal =
         addrLocalUnlocked.IsValid() ? addrLocalUnlocked.ToString() : "";
 }
 
 bool CNode::ReceiveMsgBytes(const Config &config, const char *pch,
                             uint32_t nBytes, bool &complete) {
     complete = false;
     int64_t nTimeMicros = GetTimeMicros();
     LOCK(cs_vRecv);
     nLastRecv = nTimeMicros / 1000000;
     nRecvBytes += nBytes;
     while (nBytes > 0) {
         // Absorb network data.
         int handled = m_deserializer->Read(config, pch, nBytes);
 
         if (handled < 0) {
             return false;
         }
 
         pch += handled;
         nBytes -= handled;
 
         if (m_deserializer->Complete()) {
             // decompose a transport agnostic CNetMessage from the deserializer
             CNetMessage msg = m_deserializer->GetMessage(config, nTimeMicros);
 
             // Store received bytes per message command to prevent a memory DOS,
             // only allow valid commands.
             mapMsgCmdSize::iterator i =
                 mapRecvBytesPerMsgCmd.find(msg.m_command);
             if (i == mapRecvBytesPerMsgCmd.end()) {
                 i = mapRecvBytesPerMsgCmd.find(NET_MESSAGE_COMMAND_OTHER);
             }
 
             assert(i != mapRecvBytesPerMsgCmd.end());
             i->second += msg.m_raw_message_size;
 
             // push the message to the process queue,
             vRecvMsg.push_back(std::move(msg));
 
             complete = true;
         }
     }
 
     return true;
 }
 
 void CNode::SetSendVersion(int nVersionIn) {
     // Send version may only be changed in the version message, and only one
     // version message is allowed per session. We can therefore treat this value
     // as const and even atomic as long as it's only used once a version message
     // has been successfully processed. Any attempt to set this twice is an
     // error.
     if (nSendVersion != 0) {
         error("Send version already set for node: %i. Refusing to change from "
               "%i to %i",
               id, nSendVersion, nVersionIn);
     } else {
         nSendVersion = nVersionIn;
     }
 }
 
 int CNode::GetSendVersion() const {
     // The send version should always be explicitly set to INIT_PROTO_VERSION
     // rather than using this value until SetSendVersion has been called.
     if (nSendVersion == 0) {
         error("Requesting unset send version for node: %i. Using %i", id,
               INIT_PROTO_VERSION);
         return INIT_PROTO_VERSION;
     }
     return nSendVersion;
 }
 
 int V1TransportDeserializer::readHeader(const Config &config, const char *pch,
                                         uint32_t nBytes) {
     // copy data to temporary parsing buffer
     uint32_t nRemaining = 24 - nHdrPos;
     uint32_t nCopy = std::min(nRemaining, nBytes);
 
     memcpy(&hdrbuf[nHdrPos], pch, nCopy);
     nHdrPos += nCopy;
 
     // if header incomplete, exit
     if (nHdrPos < 24) {
         return nCopy;
     }
 
     // deserialize to CMessageHeader
     try {
         hdrbuf >> hdr;
     } catch (const std::exception &) {
         return -1;
     }
 
     // Reject oversized messages
     if (hdr.IsOversized(config)) {
         LogPrint(BCLog::NET, "Oversized header detected\n");
         return -1;
     }
 
     // switch state to reading message data
     in_data = true;
 
     return nCopy;
 }
 
 int V1TransportDeserializer::readData(const char *pch, uint32_t nBytes) {
     unsigned int nRemaining = hdr.nMessageSize - nDataPos;
     unsigned int nCopy = std::min(nRemaining, nBytes);
 
     if (vRecv.size() < nDataPos + nCopy) {
         // Allocate up to 256 KiB ahead, but never more than the total message
         // size.
         vRecv.resize(std::min(hdr.nMessageSize, nDataPos + nCopy + 256 * 1024));
     }
 
     hasher.Write((const uint8_t *)pch, nCopy);
     memcpy(&vRecv[nDataPos], pch, nCopy);
     nDataPos += nCopy;
 
     return nCopy;
 }
 
 const uint256 &V1TransportDeserializer::GetMessageHash() const {
     assert(Complete());
     if (data_hash.IsNull()) {
         hasher.Finalize(data_hash.begin());
     }
     return data_hash;
 }
 
 CNetMessage V1TransportDeserializer::GetMessage(const Config &config,
                                                 int64_t time) {
     // decompose a single CNetMessage from the TransportDeserializer
     CNetMessage msg(std::move(vRecv));
 
     // store state about valid header, netmagic and checksum
     msg.m_valid_header = hdr.IsValid(config);
     // FIXME Split CheckHeaderMagicAndCommand() into CheckHeaderMagic() and
     // CheckCommand() to prevent the net magic check code duplication.
     msg.m_valid_netmagic =
         (memcmp(std::begin(hdr.pchMessageStart),
                 std::begin(config.GetChainParams().NetMagic()),
                 CMessageHeader::MESSAGE_START_SIZE) == 0);
     uint256 hash = GetMessageHash();
 
     // store command string, payload size
     msg.m_command = hdr.GetCommand();
     msg.m_message_size = hdr.nMessageSize;
     msg.m_raw_message_size = hdr.nMessageSize + CMessageHeader::HEADER_SIZE;
 
     // We just received a message off the wire, harvest entropy from the time
     // (and the message checksum)
     RandAddEvent(ReadLE32(hash.begin()));
 
     msg.m_valid_checksum = (memcmp(hash.begin(), hdr.pchChecksum,
                                    CMessageHeader::CHECKSUM_SIZE) == 0);
 
     if (!msg.m_valid_checksum) {
         LogPrint(
             BCLog::NET, "CHECKSUM ERROR (%s, %u bytes), expected %s was %s\n",
             SanitizeString(msg.m_command), msg.m_message_size,
             HexStr(hash.begin(), hash.begin() + CMessageHeader::CHECKSUM_SIZE),
             HexStr(hdr.pchChecksum,
                    hdr.pchChecksum + CMessageHeader::CHECKSUM_SIZE));
     }
 
     // store receive time
     msg.m_time = time;
 
     // reset the network deserializer (prepare for the next message)
     Reset();
     return msg;
 }
 
+void V1TransportSerializer::prepareForTransport(const Config &config,
+                                                CSerializedNetMsg &msg,
+                                                std::vector<uint8_t> &header) {
+    // create dbl-sha256 checksum
+    uint256 hash = Hash(msg.data.begin(), msg.data.end());
+
+    // create header
+    CMessageHeader hdr(config.GetChainParams().NetMagic(), msg.command.c_str(),
+                       msg.data.size());
+    memcpy(hdr.pchChecksum, hash.begin(), CMessageHeader::CHECKSUM_SIZE);
+
+    // serialize header
+    header.reserve(CMessageHeader::HEADER_SIZE);
+    CVectorWriter{SER_NETWORK, INIT_PROTO_VERSION, header, 0, hdr};
+}
+
 size_t CConnman::SocketSendData(CNode *pnode) const
     EXCLUSIVE_LOCKS_REQUIRED(pnode->cs_vSend) {
     size_t nSentSize = 0;
     size_t nMsgCount = 0;
 
     for (const auto &data : pnode->vSendMsg) {
         assert(data.size() > pnode->nSendOffset);
         int nBytes = 0;
 
         {
             LOCK(pnode->cs_hSocket);
             if (pnode->hSocket == INVALID_SOCKET) {
                 break;
             }
 
             nBytes = send(pnode->hSocket,
                           reinterpret_cast<const char *>(data.data()) +
                               pnode->nSendOffset,
                           data.size() - pnode->nSendOffset,
                           MSG_NOSIGNAL | MSG_DONTWAIT);
         }
 
         if (nBytes == 0) {
             // couldn't send anything at all
             break;
         }
 
         if (nBytes < 0) {
             // error
             int nErr = WSAGetLastError();
             if (nErr != WSAEWOULDBLOCK && nErr != WSAEMSGSIZE &&
                 nErr != WSAEINTR && nErr != WSAEINPROGRESS) {
                 LogPrintf("socket send error %s\n", NetworkErrorString(nErr));
                 pnode->CloseSocketDisconnect();
             }
 
             break;
         }
 
         assert(nBytes > 0);
         pnode->nLastSend = GetSystemTimeInSeconds();
         pnode->nSendBytes += nBytes;
         pnode->nSendOffset += nBytes;
         nSentSize += nBytes;
         if (pnode->nSendOffset != data.size()) {
             // could not send full message; stop sending more
             break;
         }
 
         pnode->nSendOffset = 0;
         pnode->nSendSize -= data.size();
         pnode->fPauseSend = pnode->nSendSize > nSendBufferMaxSize;
         nMsgCount++;
     }
 
     pnode->vSendMsg.erase(pnode->vSendMsg.begin(),
                           pnode->vSendMsg.begin() + nMsgCount);
 
     if (pnode->vSendMsg.empty()) {
         assert(pnode->nSendOffset == 0);
         assert(pnode->nSendSize == 0);
     }
 
     return nSentSize;
 }
 
 struct NodeEvictionCandidate {
     NodeId id;
     int64_t nTimeConnected;
     int64_t nMinPingUsecTime;
     int64_t nLastBlockTime;
     int64_t nLastTXTime;
     bool fRelevantServices;
     bool fRelayTxes;
     bool fBloomFilter;
     CAddress addr;
     uint64_t nKeyedNetGroup;
     bool prefer_evict;
 };
 
 static bool ReverseCompareNodeMinPingTime(const NodeEvictionCandidate &a,
                                           const NodeEvictionCandidate &b) {
     return a.nMinPingUsecTime > b.nMinPingUsecTime;
 }
 
 static bool ReverseCompareNodeTimeConnected(const NodeEvictionCandidate &a,
                                             const NodeEvictionCandidate &b) {
     return a.nTimeConnected > b.nTimeConnected;
 }
 
 static bool CompareNetGroupKeyed(const NodeEvictionCandidate &a,
                                  const NodeEvictionCandidate &b) {
     return a.nKeyedNetGroup < b.nKeyedNetGroup;
 }
 
 static bool CompareNodeBlockTime(const NodeEvictionCandidate &a,
                                  const NodeEvictionCandidate &b) {
     // There is a fall-through here because it is common for a node to have many
     // peers which have not yet relayed a block.
     if (a.nLastBlockTime != b.nLastBlockTime) {
         return a.nLastBlockTime < b.nLastBlockTime;
     }
 
     if (a.fRelevantServices != b.fRelevantServices) {
         return b.fRelevantServices;
     }
 
     return a.nTimeConnected > b.nTimeConnected;
 }
 
 static bool CompareNodeTXTime(const NodeEvictionCandidate &a,
                               const NodeEvictionCandidate &b) {
     // There is a fall-through here because it is common for a node to have more
     // than a few peers that have not yet relayed txn.
     if (a.nLastTXTime != b.nLastTXTime) {
         return a.nLastTXTime < b.nLastTXTime;
     }
 
     if (a.fRelayTxes != b.fRelayTxes) {
         return b.fRelayTxes;
     }
 
     if (a.fBloomFilter != b.fBloomFilter) {
         return a.fBloomFilter;
     }
 
     return a.nTimeConnected > b.nTimeConnected;
 }
 
 //! Sort an array by the specified comparator, then erase the last K elements.
 template <typename T, typename Comparator>
 static void EraseLastKElements(std::vector<T> &elements, Comparator comparator,
                                size_t k) {
     std::sort(elements.begin(), elements.end(), comparator);
     size_t eraseSize = std::min(k, elements.size());
     elements.erase(elements.end() - eraseSize, elements.end());
 }
 
 /**
  * Try to find a connection to evict when the node is full.
  * Extreme care must be taken to avoid opening the node to attacker triggered
  * network partitioning.
  * The strategy used here is to protect a small number of peers for each of
  * several distinct characteristics which are difficult to forge. In order to
  * partition a node the attacker must be simultaneously better at all of them
  * than honest peers.
  */
 bool CConnman::AttemptToEvictConnection() {
     std::vector<NodeEvictionCandidate> vEvictionCandidates;
     {
         LOCK(cs_vNodes);
 
         for (const CNode *node : vNodes) {
             if (node->HasPermission(PF_NOBAN)) {
                 continue;
             }
             if (!node->fInbound) {
                 continue;
             }
             if (node->fDisconnect) {
                 continue;
             }
             bool peer_relay_txes = false;
             bool peer_filter_not_null = false;
             if (node->m_tx_relay != nullptr) {
                 LOCK(node->m_tx_relay->cs_filter);
                 peer_relay_txes = node->m_tx_relay->fRelayTxes;
                 peer_filter_not_null = node->m_tx_relay->pfilter != nullptr;
             }
             NodeEvictionCandidate candidate = {
                 node->GetId(),
                 node->nTimeConnected,
                 node->nMinPingUsecTime,
                 node->nLastBlockTime,
                 node->nLastTXTime,
                 HasAllDesirableServiceFlags(node->nServices),
                 peer_relay_txes,
                 peer_filter_not_null,
                 node->addr,
                 node->nKeyedNetGroup,
                 node->m_prefer_evict};
             vEvictionCandidates.push_back(candidate);
         }
     }
 
     // Protect connections with certain characteristics
 
     // Deterministically select 4 peers to protect by netgroup.
     // An attacker cannot predict which netgroups will be protected
     EraseLastKElements(vEvictionCandidates, CompareNetGroupKeyed, 4);
     // Protect the 8 nodes with the lowest minimum ping time.
     // An attacker cannot manipulate this metric without physically moving nodes
     // closer to the target.
     EraseLastKElements(vEvictionCandidates, ReverseCompareNodeMinPingTime, 8);
     // Protect 4 nodes that most recently sent us transactions.
     // An attacker cannot manipulate this metric without performing useful work.
     EraseLastKElements(vEvictionCandidates, CompareNodeTXTime, 4);
     // Protect 4 nodes that most recently sent us blocks.
     // An attacker cannot manipulate this metric without performing useful work.
     EraseLastKElements(vEvictionCandidates, CompareNodeBlockTime, 4);
     // Protect the half of the remaining nodes which have been connected the
     // longest. This replicates the non-eviction implicit behavior, and
     // precludes attacks that start later.
     EraseLastKElements(vEvictionCandidates, ReverseCompareNodeTimeConnected,
                        vEvictionCandidates.size() / 2);
 
     if (vEvictionCandidates.empty()) {
         return false;
     }
 
     // If any remaining peers are preferred for eviction consider only them.
     // This happens after the other preferences since if a peer is really the
     // best by other criteria (esp relaying blocks)
     // then we probably don't want to evict it no matter what.
     if (std::any_of(
             vEvictionCandidates.begin(), vEvictionCandidates.end(),
             [](NodeEvictionCandidate const &n) { return n.prefer_evict; })) {
         vEvictionCandidates.erase(
             std::remove_if(
                 vEvictionCandidates.begin(), vEvictionCandidates.end(),
                 [](NodeEvictionCandidate const &n) { return !n.prefer_evict; }),
             vEvictionCandidates.end());
     }
 
     // Identify the network group with the most connections and youngest member.
     // (vEvictionCandidates is already sorted by reverse connect time)
     uint64_t naMostConnections;
     unsigned int nMostConnections = 0;
     int64_t nMostConnectionsTime = 0;
     std::map<uint64_t, std::vector<NodeEvictionCandidate>> mapNetGroupNodes;
     for (const NodeEvictionCandidate &node : vEvictionCandidates) {
         std::vector<NodeEvictionCandidate> &group =
             mapNetGroupNodes[node.nKeyedNetGroup];
         group.push_back(node);
         int64_t grouptime = group[0].nTimeConnected;
         size_t group_size = group.size();
         if (group_size > nMostConnections ||
             (group_size == nMostConnections &&
              grouptime > nMostConnectionsTime)) {
             nMostConnections = group_size;
             nMostConnectionsTime = grouptime;
             naMostConnections = node.nKeyedNetGroup;
         }
     }
 
     // Reduce to the network group with the most connections
     vEvictionCandidates = std::move(mapNetGroupNodes[naMostConnections]);
 
     // Disconnect from the network group with the most connections
     NodeId evicted = vEvictionCandidates.front().id;
     LOCK(cs_vNodes);
     for (CNode *pnode : vNodes) {
         if (pnode->GetId() == evicted) {
             pnode->fDisconnect = true;
             return true;
         }
     }
     return false;
 }
 
 void CConnman::AcceptConnection(const ListenSocket &hListenSocket) {
     struct sockaddr_storage sockaddr;
     socklen_t len = sizeof(sockaddr);
     SOCKET hSocket =
         accept(hListenSocket.socket, (struct sockaddr *)&sockaddr, &len);
     CAddress addr;
     int nInbound = 0;
     int nMaxInbound = nMaxConnections - m_max_outbound;
 
     if (hSocket != INVALID_SOCKET) {
         if (!addr.SetSockAddr((const struct sockaddr *)&sockaddr)) {
             LogPrintf("Warning: Unknown socket family\n");
         }
     }
 
     NetPermissionFlags permissionFlags = NetPermissionFlags::PF_NONE;
     hListenSocket.AddSocketPermissionFlags(permissionFlags);
     AddWhitelistPermissionFlags(permissionFlags, addr);
     bool legacyWhitelisted = false;
     if (NetPermissions::HasFlag(permissionFlags,
                                 NetPermissionFlags::PF_ISIMPLICIT)) {
         NetPermissions::ClearFlag(permissionFlags, PF_ISIMPLICIT);
         if (gArgs.GetBoolArg("-whitelistforcerelay",
                              DEFAULT_WHITELISTFORCERELAY)) {
             NetPermissions::AddFlag(permissionFlags, PF_FORCERELAY);
         }
         if (gArgs.GetBoolArg("-whitelistrelay", DEFAULT_WHITELISTRELAY)) {
             NetPermissions::AddFlag(permissionFlags, PF_RELAY);
         }
         NetPermissions::AddFlag(permissionFlags, PF_MEMPOOL);
         NetPermissions::AddFlag(permissionFlags, PF_NOBAN);
         legacyWhitelisted = true;
     }
 
     {
         LOCK(cs_vNodes);
         for (const CNode *pnode : vNodes) {
             if (pnode->fInbound) {
                 nInbound++;
             }
         }
     }
 
     if (hSocket == INVALID_SOCKET) {
         int nErr = WSAGetLastError();
         if (nErr != WSAEWOULDBLOCK) {
             LogPrintf("socket error accept failed: %s\n",
                       NetworkErrorString(nErr));
         }
         return;
     }
 
     if (!fNetworkActive) {
         LogPrintf("connection from %s dropped: not accepting new connections\n",
                   addr.ToString());
         CloseSocket(hSocket);
         return;
     }
 
     if (!IsSelectableSocket(hSocket)) {
         LogPrintf("connection from %s dropped: non-selectable socket\n",
                   addr.ToString());
         CloseSocket(hSocket);
         return;
     }
 
     // According to the internet TCP_NODELAY is not carried into accepted
     // sockets on all platforms.  Set it again here just to be sure.
     SetSocketNoDelay(hSocket);
 
     // Don't accept connections from banned peers.
     bool banned = m_banman->IsBanned(addr);
     if (!NetPermissions::HasFlag(permissionFlags,
                                  NetPermissionFlags::PF_NOBAN) &&
         banned) {
         LogPrint(BCLog::NET, "connection from %s dropped (banned)\n",
                  addr.ToString());
         CloseSocket(hSocket);
         return;
     }
 
     // Only accept connections from discouraged peers if our inbound slots
     // aren't (almost) full.
     bool discouraged = m_banman->IsDiscouraged(addr);
     if (!NetPermissions::HasFlag(permissionFlags,
                                  NetPermissionFlags::PF_NOBAN) &&
         nInbound + 1 >= nMaxInbound && discouraged) {
         LogPrint(BCLog::NET, "connection from %s dropped (discouraged)\n",
                  addr.ToString());
         CloseSocket(hSocket);
         return;
     }
 
     if (nInbound >= nMaxInbound) {
         if (!AttemptToEvictConnection()) {
             // No connection to evict, disconnect the new connection
             LogPrint(BCLog::NET, "failed to find an eviction candidate - "
                                  "connection dropped (full)\n");
             CloseSocket(hSocket);
             return;
         }
     }
 
     NodeId id = GetNewNodeId();
     uint64_t nonce = GetDeterministicRandomizer(RANDOMIZER_ID_LOCALHOSTNONCE)
                          .Write(id)
                          .Finalize();
     CAddress addr_bind = GetBindAddress(hSocket);
 
     ServiceFlags nodeServices = nLocalServices;
     if (NetPermissions::HasFlag(permissionFlags, PF_BLOOMFILTER)) {
         nodeServices = static_cast<ServiceFlags>(nodeServices | NODE_BLOOM);
     }
     CNode *pnode =
         new CNode(id, nodeServices, GetBestHeight(), hSocket, addr,
                   CalculateKeyedNetGroup(addr), nonce, addr_bind, "", true);
     pnode->AddRef();
     pnode->m_permissionFlags = permissionFlags;
     // If this flag is present, the user probably expect that RPC and QT report
     // it as whitelisted (backward compatibility)
     pnode->m_legacyWhitelisted = legacyWhitelisted;
     pnode->m_prefer_evict = discouraged;
     m_msgproc->InitializeNode(*config, pnode);
 
     LogPrint(BCLog::NET, "connection from %s accepted\n", addr.ToString());
 
     {
         LOCK(cs_vNodes);
         vNodes.push_back(pnode);
     }
 
     // We received a new connection, harvest entropy from the time (and our peer
     // count)
     RandAddEvent((uint32_t)id);
 }
 
 void CConnman::DisconnectNodes() {
     {
         LOCK(cs_vNodes);
 
         if (!fNetworkActive) {
             // Disconnect any connected nodes
             for (CNode *pnode : vNodes) {
                 if (!pnode->fDisconnect) {
                     LogPrint(BCLog::NET,
                              "Network not active, dropping peer=%d\n",
                              pnode->GetId());
                     pnode->fDisconnect = true;
                 }
             }
         }
 
         // Disconnect unused nodes
         std::vector<CNode *> vNodesCopy = vNodes;
         for (CNode *pnode : vNodesCopy) {
             if (pnode->fDisconnect) {
                 // remove from vNodes
                 vNodes.erase(remove(vNodes.begin(), vNodes.end(), pnode),
                              vNodes.end());
 
                 // release outbound grant (if any)
                 pnode->grantOutbound.Release();
 
                 // close socket and cleanup
                 pnode->CloseSocketDisconnect();
 
                 // hold in disconnected pool until all refs are released
                 pnode->Release();
                 vNodesDisconnected.push_back(pnode);
             }
         }
     }
     {
         // Delete disconnected nodes
         std::list<CNode *> vNodesDisconnectedCopy = vNodesDisconnected;
         for (CNode *pnode : vNodesDisconnectedCopy) {
             // wait until threads are done using it
             if (pnode->GetRefCount() <= 0) {
                 bool fDelete = false;
                 {
                     TRY_LOCK(pnode->cs_inventory, lockInv);
                     if (lockInv) {
                         TRY_LOCK(pnode->cs_vSend, lockSend);
                         if (lockSend) {
                             fDelete = true;
                         }
                     }
                 }
                 if (fDelete) {
                     vNodesDisconnected.remove(pnode);
                     DeleteNode(pnode);
                 }
             }
         }
     }
 }
 
 void CConnman::NotifyNumConnectionsChanged() {
     size_t vNodesSize;
     {
         LOCK(cs_vNodes);
         vNodesSize = vNodes.size();
     }
     if (vNodesSize != nPrevNodeCount) {
         nPrevNodeCount = vNodesSize;
         if (clientInterface) {
             clientInterface->NotifyNumConnectionsChanged(vNodesSize);
         }
     }
 }
 
 void CConnman::InactivityCheck(CNode *pnode) {
     int64_t nTime = GetSystemTimeInSeconds();
     if (nTime - pnode->nTimeConnected > m_peer_connect_timeout) {
         if (pnode->nLastRecv == 0 || pnode->nLastSend == 0) {
             LogPrint(BCLog::NET,
                      "socket no message in first %i seconds, %d %d from %d\n",
                      m_peer_connect_timeout, pnode->nLastRecv != 0,
                      pnode->nLastSend != 0, pnode->GetId());
             pnode->fDisconnect = true;
         } else if (nTime - pnode->nLastSend > TIMEOUT_INTERVAL) {
             LogPrintf("socket sending timeout: %is\n",
                       nTime - pnode->nLastSend);
             pnode->fDisconnect = true;
         } else if (nTime - pnode->nLastRecv > (pnode->nVersion > BIP0031_VERSION
                                                    ? TIMEOUT_INTERVAL
                                                    : 90 * 60)) {
             LogPrintf("socket receive timeout: %is\n",
                       nTime - pnode->nLastRecv);
             pnode->fDisconnect = true;
         } else if (pnode->nPingNonceSent &&
                    pnode->nPingUsecStart + TIMEOUT_INTERVAL * 1000000 <
                        GetTimeMicros()) {
             LogPrintf("ping timeout: %fs\n",
                       0.000001 * (GetTimeMicros() - pnode->nPingUsecStart));
             pnode->fDisconnect = true;
         } else if (!pnode->fSuccessfullyConnected) {
             LogPrint(BCLog::NET, "version handshake timeout from %d\n",
                      pnode->GetId());
             pnode->fDisconnect = true;
         }
     }
 }
 
 bool CConnman::GenerateSelectSet(std::set<SOCKET> &recv_set,
                                  std::set<SOCKET> &send_set,
                                  std::set<SOCKET> &error_set) {
     for (const ListenSocket &hListenSocket : vhListenSocket) {
         recv_set.insert(hListenSocket.socket);
     }
 
     {
         LOCK(cs_vNodes);
         for (CNode *pnode : vNodes) {
             // Implement the following logic:
             // * If there is data to send, select() for sending data. As this
             //   only happens when optimistic write failed, we choose to first
             //   drain the write buffer in this case before receiving more. This
             //   avoids needlessly queueing received data, if the remote peer is
             //   not themselves receiving data. This means properly utilizing
             //   TCP flow control signalling.
             // * Otherwise, if there is space left in the receive buffer,
             //   select() for receiving data.
             // * Hand off all complete messages to the processor, to be handled
             //   without blocking here.
 
             bool select_recv = !pnode->fPauseRecv;
             bool select_send;
             {
                 LOCK(pnode->cs_vSend);
                 select_send = !pnode->vSendMsg.empty();
             }
 
             LOCK(pnode->cs_hSocket);
             if (pnode->hSocket == INVALID_SOCKET) {
                 continue;
             }
 
             error_set.insert(pnode->hSocket);
             if (select_send) {
                 send_set.insert(pnode->hSocket);
                 continue;
             }
             if (select_recv) {
                 recv_set.insert(pnode->hSocket);
             }
         }
     }
 
     return !recv_set.empty() || !send_set.empty() || !error_set.empty();
 }
 
 #ifdef USE_POLL
 void CConnman::SocketEvents(std::set<SOCKET> &recv_set,
                             std::set<SOCKET> &send_set,
                             std::set<SOCKET> &error_set) {
     std::set<SOCKET> recv_select_set, send_select_set, error_select_set;
     if (!GenerateSelectSet(recv_select_set, send_select_set,
                            error_select_set)) {
         interruptNet.sleep_for(
             std::chrono::milliseconds(SELECT_TIMEOUT_MILLISECONDS));
         return;
     }
 
     std::unordered_map<SOCKET, struct pollfd> pollfds;
     for (SOCKET socket_id : recv_select_set) {
         pollfds[socket_id].fd = socket_id;
         pollfds[socket_id].events |= POLLIN;
     }
 
     for (SOCKET socket_id : send_select_set) {
         pollfds[socket_id].fd = socket_id;
         pollfds[socket_id].events |= POLLOUT;
     }
 
     for (SOCKET socket_id : error_select_set) {
         pollfds[socket_id].fd = socket_id;
         // These flags are ignored, but we set them for clarity
         pollfds[socket_id].events |= POLLERR | POLLHUP;
     }
 
     std::vector<struct pollfd> vpollfds;
     vpollfds.reserve(pollfds.size());
     for (auto it : pollfds) {
         vpollfds.push_back(std::move(it.second));
     }
 
     if (poll(vpollfds.data(), vpollfds.size(), SELECT_TIMEOUT_MILLISECONDS) <
         0) {
         return;
     }
 
     if (interruptNet) {
         return;
     }
 
     for (struct pollfd pollfd_entry : vpollfds) {
         if (pollfd_entry.revents & POLLIN) {
             recv_set.insert(pollfd_entry.fd);
         }
         if (pollfd_entry.revents & POLLOUT) {
             send_set.insert(pollfd_entry.fd);
         }
         if (pollfd_entry.revents & (POLLERR | POLLHUP)) {
             error_set.insert(pollfd_entry.fd);
         }
     }
 }
 #else
 void CConnman::SocketEvents(std::set<SOCKET> &recv_set,
                             std::set<SOCKET> &send_set,
                             std::set<SOCKET> &error_set) {
     std::set<SOCKET> recv_select_set, send_select_set, error_select_set;
     if (!GenerateSelectSet(recv_select_set, send_select_set,
                            error_select_set)) {
         interruptNet.sleep_for(
             std::chrono::milliseconds(SELECT_TIMEOUT_MILLISECONDS));
         return;
     }
 
     //
     // Find which sockets have data to receive
     //
     struct timeval timeout;
     timeout.tv_sec = 0;
     // frequency to poll pnode->vSend
     timeout.tv_usec = SELECT_TIMEOUT_MILLISECONDS * 1000;
 
     fd_set fdsetRecv;
     fd_set fdsetSend;
     fd_set fdsetError;
     FD_ZERO(&fdsetRecv);
     FD_ZERO(&fdsetSend);
     FD_ZERO(&fdsetError);
     SOCKET hSocketMax = 0;
 
     for (SOCKET hSocket : recv_select_set) {
         FD_SET(hSocket, &fdsetRecv);
         hSocketMax = std::max(hSocketMax, hSocket);
     }
 
     for (SOCKET hSocket : send_select_set) {
         FD_SET(hSocket, &fdsetSend);
         hSocketMax = std::max(hSocketMax, hSocket);
     }
 
     for (SOCKET hSocket : error_select_set) {
         FD_SET(hSocket, &fdsetError);
         hSocketMax = std::max(hSocketMax, hSocket);
     }
 
     int nSelect =
         select(hSocketMax + 1, &fdsetRecv, &fdsetSend, &fdsetError, &timeout);
 
     if (interruptNet) {
         return;
     }
 
     if (nSelect == SOCKET_ERROR) {
         int nErr = WSAGetLastError();
         LogPrintf("socket select error %s\n", NetworkErrorString(nErr));
         for (unsigned int i = 0; i <= hSocketMax; i++) {
             FD_SET(i, &fdsetRecv);
         }
         FD_ZERO(&fdsetSend);
         FD_ZERO(&fdsetError);
         if (!interruptNet.sleep_for(
                 std::chrono::milliseconds(SELECT_TIMEOUT_MILLISECONDS))) {
             return;
         }
     }
 
     for (SOCKET hSocket : recv_select_set) {
         if (FD_ISSET(hSocket, &fdsetRecv)) {
             recv_set.insert(hSocket);
         }
     }
 
     for (SOCKET hSocket : send_select_set) {
         if (FD_ISSET(hSocket, &fdsetSend)) {
             send_set.insert(hSocket);
         }
     }
 
     for (SOCKET hSocket : error_select_set) {
         if (FD_ISSET(hSocket, &fdsetError)) {
             error_set.insert(hSocket);
         }
     }
 }
 #endif
 
 void CConnman::SocketHandler() {
     std::set<SOCKET> recv_set, send_set, error_set;
     SocketEvents(recv_set, send_set, error_set);
 
     if (interruptNet) {
         return;
     }
 
     //
     // Accept new connections
     //
     for (const ListenSocket &hListenSocket : vhListenSocket) {
         if (hListenSocket.socket != INVALID_SOCKET &&
             recv_set.count(hListenSocket.socket) > 0) {
             AcceptConnection(hListenSocket);
         }
     }
 
     //
     // Service each socket
     //
     std::vector<CNode *> vNodesCopy;
     {
         LOCK(cs_vNodes);
         vNodesCopy = vNodes;
         for (CNode *pnode : vNodesCopy) {
             pnode->AddRef();
         }
     }
     for (CNode *pnode : vNodesCopy) {
         if (interruptNet) {
             return;
         }
 
         //
         // Receive
         //
         bool recvSet = false;
         bool sendSet = false;
         bool errorSet = false;
         {
             LOCK(pnode->cs_hSocket);
             if (pnode->hSocket == INVALID_SOCKET) {
                 continue;
             }
             recvSet = recv_set.count(pnode->hSocket) > 0;
             sendSet = send_set.count(pnode->hSocket) > 0;
             errorSet = error_set.count(pnode->hSocket) > 0;
         }
         if (recvSet || errorSet) {
             // typical socket buffer is 8K-64K
             char pchBuf[0x10000];
             int32_t nBytes = 0;
             {
                 LOCK(pnode->cs_hSocket);
                 if (pnode->hSocket == INVALID_SOCKET) {
                     continue;
                 }
                 nBytes =
                     recv(pnode->hSocket, pchBuf, sizeof(pchBuf), MSG_DONTWAIT);
             }
             if (nBytes > 0) {
                 bool notify = false;
                 if (!pnode->ReceiveMsgBytes(*config, pchBuf, nBytes, notify)) {
                     pnode->CloseSocketDisconnect();
                 }
                 RecordBytesRecv(nBytes);
                 if (notify) {
                     size_t nSizeAdded = 0;
                     auto it(pnode->vRecvMsg.begin());
                     for (; it != pnode->vRecvMsg.end(); ++it) {
                         // vRecvMsg contains only completed CNetMessage
                         // the single possible partially deserialized message
                         // are held by TransportDeserializer
                         nSizeAdded += it->m_raw_message_size;
                     }
                     {
                         LOCK(pnode->cs_vProcessMsg);
                         pnode->vProcessMsg.splice(pnode->vProcessMsg.end(),
                                                   pnode->vRecvMsg,
                                                   pnode->vRecvMsg.begin(), it);
                         pnode->nProcessQueueSize += nSizeAdded;
                         pnode->fPauseRecv =
                             pnode->nProcessQueueSize > nReceiveFloodSize;
                     }
                     WakeMessageHandler();
                 }
             } else if (nBytes == 0) {
                 // socket closed gracefully
                 if (!pnode->fDisconnect) {
                     LogPrint(BCLog::NET, "socket closed for peer=%d\n",
                              pnode->GetId());
                 }
                 pnode->CloseSocketDisconnect();
             } else if (nBytes < 0) {
                 // error
                 int nErr = WSAGetLastError();
                 if (nErr != WSAEWOULDBLOCK && nErr != WSAEMSGSIZE &&
                     nErr != WSAEINTR && nErr != WSAEINPROGRESS) {
                     if (!pnode->fDisconnect) {
                         LogPrint(BCLog::NET,
                                  "socket recv error for peer=%d: %s\n",
                                  pnode->GetId(), NetworkErrorString(nErr));
                     }
                     pnode->CloseSocketDisconnect();
                 }
             }
         }
 
         //
         // Send
         //
         if (sendSet) {
             LOCK(pnode->cs_vSend);
             size_t nBytes = SocketSendData(pnode);
             if (nBytes) {
                 RecordBytesSent(nBytes);
             }
         }
 
         InactivityCheck(pnode);
     }
     {
         LOCK(cs_vNodes);
         for (CNode *pnode : vNodesCopy) {
             pnode->Release();
         }
     }
 }
 
 void CConnman::ThreadSocketHandler() {
     while (!interruptNet) {
         DisconnectNodes();
         NotifyNumConnectionsChanged();
         SocketHandler();
     }
 }
 
 void CConnman::WakeMessageHandler() {
     {
         LOCK(mutexMsgProc);
         fMsgProcWake = true;
     }
     condMsgProc.notify_one();
 }
 
 #ifdef USE_UPNP
 static CThreadInterrupt g_upnp_interrupt;
 static std::thread g_upnp_thread;
 static void ThreadMapPort() {
     std::string port = strprintf("%u", GetListenPort());
     const char *multicastif = nullptr;
     const char *minissdpdpath = nullptr;
     struct UPNPDev *devlist = nullptr;
     char lanaddr[64];
 
     int error = 0;
 #if MINIUPNPC_API_VERSION < 14
     devlist = upnpDiscover(2000, multicastif, minissdpdpath, 0, 0, &error);
 #else
     devlist = upnpDiscover(2000, multicastif, minissdpdpath, 0, 0, 2, &error);
 #endif
 
     struct UPNPUrls urls;
     struct IGDdatas data;
     int r;
 
     r = UPNP_GetValidIGD(devlist, &urls, &data, lanaddr, sizeof(lanaddr));
     if (r == 1) {
         if (fDiscover) {
             char externalIPAddress[40];
             r = UPNP_GetExternalIPAddress(
                 urls.controlURL, data.first.servicetype, externalIPAddress);
             if (r != UPNPCOMMAND_SUCCESS) {
                 LogPrintf("UPnP: GetExternalIPAddress() returned %d\n", r);
             } else {
                 if (externalIPAddress[0]) {
                     CNetAddr resolved;
                     if (LookupHost(externalIPAddress, resolved, false)) {
                         LogPrintf("UPnP: ExternalIPAddress = %s\n",
                                   resolved.ToString());
                         AddLocal(resolved, LOCAL_UPNP);
                     }
                 } else {
                     LogPrintf("UPnP: GetExternalIPAddress failed.\n");
                 }
             }
         }
 
         std::string strDesc = PACKAGE_NAME " " + FormatFullVersion();
 
         do {
             r = UPNP_AddPortMapping(urls.controlURL, data.first.servicetype,
                                     port.c_str(), port.c_str(), lanaddr,
                                     strDesc.c_str(), "TCP", 0, "0");
 
             if (r != UPNPCOMMAND_SUCCESS) {
                 LogPrintf(
                     "AddPortMapping(%s, %s, %s) failed with code %d (%s)\n",
                     port, port, lanaddr, r, strupnperror(r));
             } else {
                 LogPrintf("UPnP Port Mapping successful.\n");
             }
         } while (g_upnp_interrupt.sleep_for(std::chrono::minutes(20)));
 
         r = UPNP_DeletePortMapping(urls.controlURL, data.first.servicetype,
                                    port.c_str(), "TCP", 0);
         LogPrintf("UPNP_DeletePortMapping() returned: %d\n", r);
         freeUPNPDevlist(devlist);
         devlist = nullptr;
         FreeUPNPUrls(&urls);
     } else {
         LogPrintf("No valid UPnP IGDs found\n");
         freeUPNPDevlist(devlist);
         devlist = nullptr;
         if (r != 0) {
             FreeUPNPUrls(&urls);
         }
     }
 }
 
 void StartMapPort() {
     if (!g_upnp_thread.joinable()) {
         assert(!g_upnp_interrupt);
         g_upnp_thread = std::thread(
             (std::bind(&TraceThread<void (*)()>, "upnp", &ThreadMapPort)));
     }
 }
 
 void InterruptMapPort() {
     if (g_upnp_thread.joinable()) {
         g_upnp_interrupt();
     }
 }
 
 void StopMapPort() {
     if (g_upnp_thread.joinable()) {
         g_upnp_thread.join();
         g_upnp_interrupt.reset();
     }
 }
 
 #else
 void StartMapPort() {
     // Intentionally left blank.
 }
 void InterruptMapPort() {
     // Intentionally left blank.
 }
 void StopMapPort() {
     // Intentionally left blank.
 }
 #endif
 
 void CConnman::ThreadDNSAddressSeed() {
     FastRandomContext rng;
     std::vector<std::string> seeds = config->GetChainParams().DNSSeeds();
     Shuffle(seeds.begin(), seeds.end(), rng);
     // Number of seeds left before testing if we have enough connections
     int seeds_right_now = 0;
     int found = 0;
 
     if (gArgs.GetBoolArg("-forcednsseed", DEFAULT_FORCEDNSSEED)) {
         // When -forcednsseed is provided, query all.
         seeds_right_now = seeds.size();
     }
 
     for (const std::string &seed : seeds) {
         // goal: only query DNS seed if address need is acute
         // Avoiding DNS seeds when we don't need them improves user privacy by
         // creating fewer identifying DNS requests, reduces trust by giving
         // seeds less influence on the network topology, and reduces traffic to
         // the seeds.
         if (addrman.size() > 0 && seeds_right_now == 0) {
             if (!interruptNet.sleep_for(std::chrono::seconds(11))) {
                 return;
             }
 
             LOCK(cs_vNodes);
             int nRelevant = 0;
             for (const CNode *pnode : vNodes) {
                 nRelevant += pnode->fSuccessfullyConnected && !pnode->fFeeler &&
                              !pnode->fOneShot && !pnode->m_manual_connection &&
                              !pnode->fInbound;
             }
             if (nRelevant >= 2) {
                 LogPrintf("P2P peers available. Skipped DNS seeding.\n");
                 return;
             }
             seeds_right_now += DNSSEEDS_TO_QUERY_AT_ONCE;
         }
 
         if (interruptNet) {
             return;
         }
         LogPrintf("Loading addresses from DNS seed %s\n", seed);
         if (HaveNameProxy()) {
             AddOneShot(seed);
         } else {
             std::vector<CNetAddr> vIPs;
             std::vector<CAddress> vAdd;
             ServiceFlags requiredServiceBits =
                 GetDesirableServiceFlags(NODE_NONE);
             std::string host = strprintf("x%x.%s", requiredServiceBits, seed);
             CNetAddr resolveSource;
             if (!resolveSource.SetInternal(host)) {
                 continue;
             }
 
             // Limits number of IPs learned from a DNS seed
             unsigned int nMaxIPs = 256;
             if (LookupHost(host.c_str(), vIPs, nMaxIPs, true)) {
                 for (const CNetAddr &ip : vIPs) {
                     int nOneDay = 24 * 3600;
                     CAddress addr = CAddress(
                         CService(ip, config->GetChainParams().GetDefaultPort()),
                         requiredServiceBits);
                     // Use a random age between 3 and 7 days old.
                     addr.nTime =
                         GetTime() - 3 * nOneDay - rng.randrange(4 * nOneDay);
                     vAdd.push_back(addr);
                     found++;
                 }
                 addrman.Add(vAdd, resolveSource);
             } else {
                 // We now avoid directly using results from DNS Seeds which do
                 // not support service bit filtering, instead using them as a
                 // oneshot to get nodes with our desired service bits.
                 AddOneShot(seed);
             }
         }
         --seeds_right_now;
     }
     LogPrintf("%d addresses found from DNS seeds\n", found);
 }
 
 void CConnman::DumpAddresses() {
     int64_t nStart = GetTimeMillis();
 
     CAddrDB adb(config->GetChainParams());
     adb.Write(addrman);
 
     LogPrint(BCLog::NET, "Flushed %d addresses to peers.dat  %dms\n",
              addrman.size(), GetTimeMillis() - nStart);
 }
 
 void CConnman::ProcessOneShot() {
     std::string strDest;
     {
         LOCK(cs_vOneShots);
         if (vOneShots.empty()) {
             return;
         }
         strDest = vOneShots.front();
         vOneShots.pop_front();
     }
     CAddress addr;
     CSemaphoreGrant grant(*semOutbound, true);
     if (grant) {
         OpenNetworkConnection(addr, false, &grant, strDest.c_str(), true);
     }
 }
 
 bool CConnman::GetTryNewOutboundPeer() {
     return m_try_another_outbound_peer;
 }
 
 void CConnman::SetTryNewOutboundPeer(bool flag) {
     m_try_another_outbound_peer = flag;
     LogPrint(BCLog::NET, "net: setting try another outbound peer=%s\n",
              flag ? "true" : "false");
 }
 
 // Return the number of peers we have over our outbound connection limit.
 // Exclude peers that are marked for disconnect, or are going to be disconnected
 // soon (eg one-shots and feelers).
 // Also exclude peers that haven't finished initial connection handshake yet (so
 // that we don't decide we're over our desired connection limit, and then evict
 // some peer that has finished the handshake).
 int CConnman::GetExtraOutboundCount() {
     int nOutbound = 0;
     {
         LOCK(cs_vNodes);
         for (const CNode *pnode : vNodes) {
             if (!pnode->fInbound && !pnode->m_manual_connection &&
                 !pnode->fFeeler && !pnode->fDisconnect && !pnode->fOneShot &&
                 pnode->fSuccessfullyConnected) {
                 ++nOutbound;
             }
         }
     }
     return std::max(
         nOutbound - m_max_outbound_full_relay - m_max_outbound_block_relay, 0);
 }
 
 void CConnman::ThreadOpenConnections(const std::vector<std::string> connect) {
     // Connect to specific addresses
     if (!connect.empty()) {
         for (int64_t nLoop = 0;; nLoop++) {
             ProcessOneShot();
             for (const std::string &strAddr : connect) {
                 CAddress addr(CService(), NODE_NONE);
                 OpenNetworkConnection(addr, false, nullptr, strAddr.c_str(),
                                       false, false, true);
                 for (int i = 0; i < 10 && i < nLoop; i++) {
                     if (!interruptNet.sleep_for(
                             std::chrono::milliseconds(500))) {
                         return;
                     }
                 }
             }
             if (!interruptNet.sleep_for(std::chrono::milliseconds(500))) {
                 return;
             }
         }
     }
 
     // Initiate network connections
     int64_t nStart = GetTime();
 
     // Minimum time before next feeler connection (in microseconds).
     int64_t nNextFeeler =
         PoissonNextSend(nStart * 1000 * 1000, FEELER_INTERVAL);
     while (!interruptNet) {
         ProcessOneShot();
 
         if (!interruptNet.sleep_for(std::chrono::milliseconds(500))) {
             return;
         }
 
         CSemaphoreGrant grant(*semOutbound);
         if (interruptNet) {
             return;
         }
 
         // Add seed nodes if DNS seeds are all down (an infrastructure attack?).
         if (addrman.size() == 0 && (GetTime() - nStart > 60)) {
             static bool done = false;
             if (!done) {
                 LogPrintf("Adding fixed seed nodes as DNS doesn't seem to be "
                           "available.\n");
                 CNetAddr local;
                 local.SetInternal("fixedseeds");
                 addrman.Add(convertSeed6(config->GetChainParams().FixedSeeds()),
                             local);
                 done = true;
             }
         }
 
         //
         // Choose an address to connect to based on most recently seen
         //
         CAddress addrConnect;
 
         // Only connect out to one peer per network group (/16 for IPv4).
         int nOutboundFullRelay = 0;
         int nOutboundBlockRelay = 0;
         std::set<std::vector<uint8_t>> setConnected;
         {
             LOCK(cs_vNodes);
             for (const CNode *pnode : vNodes) {
                 if (!pnode->fInbound && !pnode->m_manual_connection) {
                     // Netgroups for inbound and addnode peers are not excluded
                     // because our goal here is to not use multiple of our
                     // limited outbound slots on a single netgroup but inbound
                     // and addnode peers do not use our outbound slots. Inbound
                     // peers also have the added issue that they're attacker
                     // controlled and could be used to prevent us from
                     // connecting to particular hosts if we used them here.
                     setConnected.insert(pnode->addr.GetGroup(addrman.m_asmap));
                     if (pnode->m_tx_relay == nullptr) {
                         nOutboundBlockRelay++;
                     } else if (!pnode->fFeeler) {
                         nOutboundFullRelay++;
                     }
                 }
             }
         }
 
         // Feeler Connections
         //
         // Design goals:
         //  * Increase the number of connectable addresses in the tried table.
         //
         // Method:
         //  * Choose a random address from new and attempt to connect to it if
         //    we can connect successfully it is added to tried.
         //  * Start attempting feeler connections only after node finishes
         //    making outbound connections.
         //  * Only make a feeler connection once every few minutes.
         //
         bool fFeeler = false;
 
         if (nOutboundFullRelay >= m_max_outbound_full_relay &&
             nOutboundBlockRelay >= m_max_outbound_block_relay &&
             !GetTryNewOutboundPeer()) {
             // The current time right now (in microseconds).
             int64_t nTime = GetTimeMicros();
             if (nTime > nNextFeeler) {
                 nNextFeeler = PoissonNextSend(nTime, FEELER_INTERVAL);
                 fFeeler = true;
             } else {
                 continue;
             }
         }
 
         addrman.ResolveCollisions();
 
         int64_t nANow = GetAdjustedTime();
         int nTries = 0;
         while (!interruptNet) {
             CAddrInfo addr = addrman.SelectTriedCollision();
 
             // SelectTriedCollision returns an invalid address if it is empty.
             if (!fFeeler || !addr.IsValid()) {
                 addr = addrman.Select(fFeeler);
             }
 
             // Require outbound connections, other than feelers, to be to
             // distinct network groups
             if (!fFeeler &&
                 setConnected.count(addr.GetGroup(addrman.m_asmap))) {
                 break;
             }
 
             // if we selected an invalid or local address, restart
             if (!addr.IsValid() || IsLocal(addr)) {
                 break;
             }
 
             // If we didn't find an appropriate destination after trying 100
             // addresses fetched from addrman, stop this loop, and let the outer
             // loop run again (which sleeps, adds seed nodes, recalculates
             // already-connected network ranges, ...) before trying new addrman
             // addresses.
             nTries++;
             if (nTries > 100) {
                 break;
             }
 
             if (!IsReachable(addr)) {
                 continue;
             }
 
             // only consider very recently tried nodes after 30 failed attempts
             if (nANow - addr.nLastTry < 600 && nTries < 30) {
                 continue;
             }
 
             // for non-feelers, require all the services we'll want,
             // for feelers, only require they be a full node (only because most
             // SPV clients don't have a good address DB available)
             if (!fFeeler && !HasAllDesirableServiceFlags(addr.nServices)) {
                 continue;
             }
 
             if (fFeeler && !MayHaveUsefulAddressDB(addr.nServices)) {
                 continue;
             }
 
             // do not allow non-default ports, unless after 50 invalid addresses
             // selected already.
             if (addr.GetPort() != config->GetChainParams().GetDefaultPort() &&
                 nTries < 50) {
                 continue;
             }
 
             addrConnect = addr;
             break;
         }
 
         if (addrConnect.IsValid()) {
             if (fFeeler) {
                 // Add small amount of random noise before connection to avoid
                 // synchronization.
                 int randsleep = GetRandInt(FEELER_SLEEP_WINDOW * 1000);
                 if (!interruptNet.sleep_for(
                         std::chrono::milliseconds(randsleep))) {
                     return;
                 }
                 LogPrint(BCLog::NET, "Making feeler connection to %s\n",
                          addrConnect.ToString());
             }
 
             // Open this connection as block-relay-only if we're already at our
             // full-relay capacity, but not yet at our block-relay peer limit.
             // (It should not be possible for fFeeler to be set if we're not
             // also at our block-relay peer limit, but check against that as
             // well for sanity.)
             bool block_relay_only =
                 nOutboundBlockRelay < m_max_outbound_block_relay && !fFeeler &&
                 nOutboundFullRelay >= m_max_outbound_full_relay;
 
             OpenNetworkConnection(
                 addrConnect,
                 int(setConnected.size()) >= std::min(nMaxConnections - 1, 2),
                 &grant, nullptr, false, fFeeler, false, block_relay_only);
         }
     }
 }
 
 std::vector<AddedNodeInfo> CConnman::GetAddedNodeInfo() {
     std::vector<AddedNodeInfo> ret;
 
     std::list<std::string> lAddresses(0);
     {
         LOCK(cs_vAddedNodes);
         ret.reserve(vAddedNodes.size());
         std::copy(vAddedNodes.cbegin(), vAddedNodes.cend(),
                   std::back_inserter(lAddresses));
     }
 
     // Build a map of all already connected addresses (by IP:port and by name)
     // to inbound/outbound and resolved CService
     std::map<CService, bool> mapConnected;
     std::map<std::string, std::pair<bool, CService>> mapConnectedByName;
     {
         LOCK(cs_vNodes);
         for (const CNode *pnode : vNodes) {
             if (pnode->addr.IsValid()) {
                 mapConnected[pnode->addr] = pnode->fInbound;
             }
             std::string addrName = pnode->GetAddrName();
             if (!addrName.empty()) {
                 mapConnectedByName[std::move(addrName)] =
                     std::make_pair(pnode->fInbound,
                                    static_cast<const CService &>(pnode->addr));
             }
         }
     }
 
     for (const std::string &strAddNode : lAddresses) {
         CService service(
             LookupNumeric(strAddNode.c_str(), Params().GetDefaultPort()));
         AddedNodeInfo addedNode{strAddNode, CService(), false, false};
         if (service.IsValid()) {
             // strAddNode is an IP:port
             auto it = mapConnected.find(service);
             if (it != mapConnected.end()) {
                 addedNode.resolvedAddress = service;
                 addedNode.fConnected = true;
                 addedNode.fInbound = it->second;
             }
         } else {
             // strAddNode is a name
             auto it = mapConnectedByName.find(strAddNode);
             if (it != mapConnectedByName.end()) {
                 addedNode.resolvedAddress = it->second.second;
                 addedNode.fConnected = true;
                 addedNode.fInbound = it->second.first;
             }
         }
         ret.emplace_back(std::move(addedNode));
     }
 
     return ret;
 }
 
 void CConnman::ThreadOpenAddedConnections() {
     while (true) {
         CSemaphoreGrant grant(*semAddnode);
         std::vector<AddedNodeInfo> vInfo = GetAddedNodeInfo();
         bool tried = false;
         for (const AddedNodeInfo &info : vInfo) {
             if (!info.fConnected) {
                 if (!grant.TryAcquire()) {
                     // If we've used up our semaphore and need a new one, let's
                     // not wait here since while we are waiting the
                     // addednodeinfo state might change.
                     break;
                 }
                 tried = true;
                 CAddress addr(CService(), NODE_NONE);
                 OpenNetworkConnection(addr, false, &grant,
                                       info.strAddedNode.c_str(), false, false,
                                       true);
                 if (!interruptNet.sleep_for(std::chrono::milliseconds(500))) {
                     return;
                 }
             }
         }
         // Retry every 60 seconds if a connection was attempted, otherwise two
         // seconds.
         if (!interruptNet.sleep_for(std::chrono::seconds(tried ? 60 : 2))) {
             return;
         }
     }
 }
 
 // If successful, this moves the passed grant to the constructed node.
 void CConnman::OpenNetworkConnection(const CAddress &addrConnect,
                                      bool fCountFailure,
                                      CSemaphoreGrant *grantOutbound,
                                      const char *pszDest, bool fOneShot,
                                      bool fFeeler, bool manual_connection,
                                      bool block_relay_only) {
     //
     // Initiate outbound network connection
     //
     if (interruptNet) {
         return;
     }
     if (!fNetworkActive) {
         return;
     }
     if (!pszDest) {
         bool banned_or_discouraged =
             m_banman && (m_banman->IsDiscouraged(addrConnect) ||
                          m_banman->IsBanned(addrConnect));
         if (IsLocal(addrConnect) ||
             FindNode(static_cast<CNetAddr>(addrConnect)) ||
             banned_or_discouraged || FindNode(addrConnect.ToStringIPPort())) {
             return;
         }
     } else if (FindNode(std::string(pszDest))) {
         return;
     }
 
     CNode *pnode = ConnectNode(addrConnect, pszDest, fCountFailure,
                                manual_connection, block_relay_only);
 
     if (!pnode) {
         return;
     }
     if (grantOutbound) {
         grantOutbound->MoveTo(pnode->grantOutbound);
     }
     if (fOneShot) {
         pnode->fOneShot = true;
     }
     if (fFeeler) {
         pnode->fFeeler = true;
     }
     if (manual_connection) {
         pnode->m_manual_connection = true;
     }
 
     m_msgproc->InitializeNode(*config, pnode);
     {
         LOCK(cs_vNodes);
         vNodes.push_back(pnode);
     }
 }
 
 void CConnman::ThreadMessageHandler() {
     while (!flagInterruptMsgProc) {
         std::vector<CNode *> vNodesCopy;
         {
             LOCK(cs_vNodes);
             vNodesCopy = vNodes;
             for (CNode *pnode : vNodesCopy) {
                 pnode->AddRef();
             }
         }
 
         bool fMoreWork = false;
 
         for (CNode *pnode : vNodesCopy) {
             if (pnode->fDisconnect) {
                 continue;
             }
 
             // Receive messages
             bool fMoreNodeWork = m_msgproc->ProcessMessages(
                 *config, pnode, flagInterruptMsgProc);
             fMoreWork |= (fMoreNodeWork && !pnode->fPauseSend);
             if (flagInterruptMsgProc) {
                 return;
             }
 
             // Send messages
             {
                 LOCK(pnode->cs_sendProcessing);
                 m_msgproc->SendMessages(*config, pnode, flagInterruptMsgProc);
             }
 
             if (flagInterruptMsgProc) {
                 return;
             }
         }
 
         {
             LOCK(cs_vNodes);
             for (CNode *pnode : vNodesCopy) {
                 pnode->Release();
             }
         }
 
         WAIT_LOCK(mutexMsgProc, lock);
         if (!fMoreWork) {
             condMsgProc.wait_until(lock,
                                    std::chrono::steady_clock::now() +
                                        std::chrono::milliseconds(100),
                                    [this]() EXCLUSIVE_LOCKS_REQUIRED(
                                        mutexMsgProc) { return fMsgProcWake; });
         }
         fMsgProcWake = false;
     }
 }
 
 bool CConnman::BindListenPort(const CService &addrBind, bilingual_str &strError,
                               NetPermissionFlags permissions) {
     int nOne = 1;
 
     // Create socket for listening for incoming connections
     struct sockaddr_storage sockaddr;
     socklen_t len = sizeof(sockaddr);
     if (!addrBind.GetSockAddr((struct sockaddr *)&sockaddr, &len)) {
         strError = strprintf(
             Untranslated("Error: Bind address family for %s not supported"),
             addrBind.ToString());
         LogPrintf("%s\n", strError.original);
         return false;
     }
 
     SOCKET hListenSocket = CreateSocket(addrBind);
     if (hListenSocket == INVALID_SOCKET) {
         strError =
             strprintf(Untranslated("Error: Couldn't open socket for incoming "
                                    "connections (socket returned error %s)"),
                       NetworkErrorString(WSAGetLastError()));
         LogPrintf("%s\n", strError.original);
         return false;
     }
 
     // Allow binding if the port is still in TIME_WAIT state after
     // the program was closed and restarted.
     setsockopt(hListenSocket, SOL_SOCKET, SO_REUSEADDR, (sockopt_arg_type)&nOne,
                sizeof(int));
 
     // Some systems don't have IPV6_V6ONLY but are always v6only; others do have
     // the option and enable it by default or not. Try to enable it, if
     // possible.
     if (addrBind.IsIPv6()) {
 #ifdef IPV6_V6ONLY
         setsockopt(hListenSocket, IPPROTO_IPV6, IPV6_V6ONLY,
                    (sockopt_arg_type)&nOne, sizeof(int));
 #endif
 #ifdef WIN32
         int nProtLevel = PROTECTION_LEVEL_UNRESTRICTED;
         setsockopt(hListenSocket, IPPROTO_IPV6, IPV6_PROTECTION_LEVEL,
                    (sockopt_arg_type)&nProtLevel, sizeof(int));
 #endif
     }
 
     if (::bind(hListenSocket, (struct sockaddr *)&sockaddr, len) ==
         SOCKET_ERROR) {
         int nErr = WSAGetLastError();
         if (nErr == WSAEADDRINUSE) {
             strError = strprintf(_("Unable to bind to %s on this computer. %s "
                                    "is probably already running."),
                                  addrBind.ToString(), PACKAGE_NAME);
         } else {
             strError = strprintf(_("Unable to bind to %s on this computer "
                                    "(bind returned error %s)"),
                                  addrBind.ToString(), NetworkErrorString(nErr));
         }
         LogPrintf("%s\n", strError.original);
         CloseSocket(hListenSocket);
         return false;
     }
     LogPrintf("Bound to %s\n", addrBind.ToString());
 
     // Listen for incoming connections
     if (listen(hListenSocket, SOMAXCONN) == SOCKET_ERROR) {
         strError = strprintf(_("Error: Listening for incoming connections "
                                "failed (listen returned error %s)"),
                              NetworkErrorString(WSAGetLastError()));
         LogPrintf("%s\n", strError.original);
         CloseSocket(hListenSocket);
         return false;
     }
 
     vhListenSocket.push_back(ListenSocket(hListenSocket, permissions));
 
     if (addrBind.IsRoutable() && fDiscover && (permissions & PF_NOBAN) == 0) {
         AddLocal(addrBind, LOCAL_BIND);
     }
 
     return true;
 }
 
 void Discover() {
     if (!fDiscover) {
         return;
     }
 
 #ifdef WIN32
     // Get local host IP
     char pszHostName[256] = "";
     if (gethostname(pszHostName, sizeof(pszHostName)) != SOCKET_ERROR) {
         std::vector<CNetAddr> vaddr;
         if (LookupHost(pszHostName, vaddr, 0, true)) {
             for (const CNetAddr &addr : vaddr) {
                 if (AddLocal(addr, LOCAL_IF)) {
                     LogPrintf("%s: %s - %s\n", __func__, pszHostName,
                               addr.ToString());
                 }
             }
         }
     }
 #elif (HAVE_DECL_GETIFADDRS && HAVE_DECL_FREEIFADDRS)
     // Get local host ip
     struct ifaddrs *myaddrs;
     if (getifaddrs(&myaddrs) == 0) {
         for (struct ifaddrs *ifa = myaddrs; ifa != nullptr;
              ifa = ifa->ifa_next) {
             if (ifa->ifa_addr == nullptr || (ifa->ifa_flags & IFF_UP) == 0 ||
                 strcmp(ifa->ifa_name, "lo") == 0 ||
                 strcmp(ifa->ifa_name, "lo0") == 0) {
                 continue;
             }
             if (ifa->ifa_addr->sa_family == AF_INET) {
                 struct sockaddr_in *s4 =
                     reinterpret_cast<struct sockaddr_in *>(ifa->ifa_addr);
                 CNetAddr addr(s4->sin_addr);
                 if (AddLocal(addr, LOCAL_IF)) {
                     LogPrintf("%s: IPv4 %s: %s\n", __func__, ifa->ifa_name,
                               addr.ToString());
                 }
             } else if (ifa->ifa_addr->sa_family == AF_INET6) {
                 struct sockaddr_in6 *s6 =
                     reinterpret_cast<struct sockaddr_in6 *>(ifa->ifa_addr);
                 CNetAddr addr(s6->sin6_addr);
                 if (AddLocal(addr, LOCAL_IF)) {
                     LogPrintf("%s: IPv6 %s: %s\n", __func__, ifa->ifa_name,
                               addr.ToString());
                 }
             }
         }
         freeifaddrs(myaddrs);
     }
 #endif
 }
 
 void CConnman::SetNetworkActive(bool active) {
     LogPrint(BCLog::NET, "SetNetworkActive: %s\n", active);
 
     if (fNetworkActive == active) {
         return;
     }
 
     fNetworkActive = active;
     uiInterface.NotifyNetworkActiveChanged(fNetworkActive);
 }
 
 CConnman::CConnman(const Config &configIn, uint64_t nSeed0In, uint64_t nSeed1In)
     : config(&configIn), nSeed0(nSeed0In), nSeed1(nSeed1In) {
     SetTryNewOutboundPeer(false);
 
     Options connOptions;
     Init(connOptions);
 }
 
 NodeId CConnman::GetNewNodeId() {
     return nLastNodeId.fetch_add(1);
 }
 
 bool CConnman::Bind(const CService &addr, unsigned int flags,
                     NetPermissionFlags permissions) {
     if (!(flags & BF_EXPLICIT) && !IsReachable(addr)) {
         return false;
     }
     bilingual_str strError;
     if (!BindListenPort(addr, strError, permissions)) {
         if ((flags & BF_REPORT_ERROR) && clientInterface) {
             clientInterface->ThreadSafeMessageBox(
                 strError, "", CClientUIInterface::MSG_ERROR);
         }
         return false;
     }
     return true;
 }
 
 bool CConnman::InitBinds(
     const std::vector<CService> &binds,
     const std::vector<NetWhitebindPermissions> &whiteBinds) {
     bool fBound = false;
     for (const auto &addrBind : binds) {
         fBound |= Bind(addrBind, (BF_EXPLICIT | BF_REPORT_ERROR),
                        NetPermissionFlags::PF_NONE);
     }
     for (const auto &addrBind : whiteBinds) {
         fBound |= Bind(addrBind.m_service, (BF_EXPLICIT | BF_REPORT_ERROR),
                        addrBind.m_flags);
     }
     if (binds.empty() && whiteBinds.empty()) {
         struct in_addr inaddr_any;
         inaddr_any.s_addr = INADDR_ANY;
         struct in6_addr inaddr6_any = IN6ADDR_ANY_INIT;
         fBound |= Bind(CService(inaddr6_any, GetListenPort()), BF_NONE,
                        NetPermissionFlags::PF_NONE);
         fBound |= Bind(CService(inaddr_any, GetListenPort()),
                        !fBound ? BF_REPORT_ERROR : BF_NONE,
                        NetPermissionFlags::PF_NONE);
     }
     return fBound;
 }
 
 bool CConnman::Start(CScheduler &scheduler, const Options &connOptions) {
     Init(connOptions);
 
     {
         LOCK(cs_totalBytesRecv);
         nTotalBytesRecv = 0;
     }
     {
         LOCK(cs_totalBytesSent);
         nTotalBytesSent = 0;
         nMaxOutboundTotalBytesSentInCycle = 0;
         nMaxOutboundCycleStartTime = 0;
     }
 
     if (fListen && !InitBinds(connOptions.vBinds, connOptions.vWhiteBinds)) {
         if (clientInterface) {
             clientInterface->ThreadSafeMessageBox(
                 _("Failed to listen on any port. Use -listen=0 if you want "
                   "this."),
                 "", CClientUIInterface::MSG_ERROR);
         }
         return false;
     }
 
     for (const auto &strDest : connOptions.vSeedNodes) {
         AddOneShot(strDest);
     }
 
     if (clientInterface) {
         clientInterface->InitMessage(_("Loading P2P addresses...").translated);
     }
     // Load addresses from peers.dat
     int64_t nStart = GetTimeMillis();
     {
         CAddrDB adb(config->GetChainParams());
         if (adb.Read(addrman)) {
             LogPrintf("Loaded %i addresses from peers.dat  %dms\n",
                       addrman.size(), GetTimeMillis() - nStart);
         } else {
             // Addrman can be in an inconsistent state after failure, reset it
             addrman.Clear();
             LogPrintf("Invalid or missing peers.dat; recreating\n");
             DumpAddresses();
         }
     }
 
     uiInterface.InitMessage(_("Starting network threads...").translated);
 
     fAddressesInitialized = true;
 
     if (semOutbound == nullptr) {
         // initialize semaphore
         semOutbound = std::make_unique<CSemaphore>(
             std::min(m_max_outbound, nMaxConnections));
     }
     if (semAddnode == nullptr) {
         // initialize semaphore
         semAddnode = std::make_unique<CSemaphore>(nMaxAddnode);
     }
 
     //
     // Start threads
     //
     assert(m_msgproc);
     InterruptSocks5(false);
     interruptNet.reset();
     flagInterruptMsgProc = false;
 
     {
         LOCK(mutexMsgProc);
         fMsgProcWake = false;
     }
 
     // Send and receive from sockets, accept connections
     threadSocketHandler = std::thread(
         &TraceThread<std::function<void()>>, "net",
         std::function<void()>(std::bind(&CConnman::ThreadSocketHandler, this)));
 
     if (!gArgs.GetBoolArg("-dnsseed", true)) {
         LogPrintf("DNS seeding disabled\n");
     } else {
         threadDNSAddressSeed =
             std::thread(&TraceThread<std::function<void()>>, "dnsseed",
                         std::function<void()>(
                             std::bind(&CConnman::ThreadDNSAddressSeed, this)));
     }
 
     // Initiate outbound connections from -addnode
     threadOpenAddedConnections =
         std::thread(&TraceThread<std::function<void()>>, "addcon",
                     std::function<void()>(std::bind(
                         &CConnman::ThreadOpenAddedConnections, this)));
 
     if (connOptions.m_use_addrman_outgoing &&
         !connOptions.m_specified_outgoing.empty()) {
         if (clientInterface) {
             clientInterface->ThreadSafeMessageBox(
                 _("Cannot provide specific connections and have addrman find "
                   "outgoing connections at the same."),
                 "", CClientUIInterface::MSG_ERROR);
         }
         return false;
     }
     if (connOptions.m_use_addrman_outgoing ||
         !connOptions.m_specified_outgoing.empty()) {
         threadOpenConnections =
             std::thread(&TraceThread<std::function<void()>>, "opencon",
                         std::function<void()>(
                             std::bind(&CConnman::ThreadOpenConnections, this,
                                       connOptions.m_specified_outgoing)));
     }
 
     // Process messages
     threadMessageHandler =
         std::thread(&TraceThread<std::function<void()>>, "msghand",
                     std::function<void()>(
                         std::bind(&CConnman::ThreadMessageHandler, this)));
 
     // Dump network addresses
     scheduler.scheduleEvery(
         [this]() {
             this->DumpAddresses();
             return true;
         },
         DUMP_PEERS_INTERVAL);
 
     return true;
 }
 
 class CNetCleanup {
 public:
     CNetCleanup() {}
 
     ~CNetCleanup() {
 #ifdef WIN32
         // Shutdown Windows Sockets
         WSACleanup();
 #endif
     }
 };
 static CNetCleanup instance_of_cnetcleanup;
 
 void CConnman::Interrupt() {
     {
         LOCK(mutexMsgProc);
         flagInterruptMsgProc = true;
     }
     condMsgProc.notify_all();
 
     interruptNet();
     InterruptSocks5(true);
 
     if (semOutbound) {
         for (int i = 0; i < m_max_outbound; i++) {
             semOutbound->post();
         }
     }
 
     if (semAddnode) {
         for (int i = 0; i < nMaxAddnode; i++) {
             semAddnode->post();
         }
     }
 }
 
 void CConnman::Stop() {
     if (threadMessageHandler.joinable()) {
         threadMessageHandler.join();
     }
     if (threadOpenConnections.joinable()) {
         threadOpenConnections.join();
     }
     if (threadOpenAddedConnections.joinable()) {
         threadOpenAddedConnections.join();
     }
     if (threadDNSAddressSeed.joinable()) {
         threadDNSAddressSeed.join();
     }
     if (threadSocketHandler.joinable()) {
         threadSocketHandler.join();
     }
 
     if (fAddressesInitialized) {
         DumpAddresses();
         fAddressesInitialized = false;
     }
 
     // Close sockets
     for (CNode *pnode : vNodes) {
         pnode->CloseSocketDisconnect();
     }
     for (ListenSocket &hListenSocket : vhListenSocket) {
         if (hListenSocket.socket != INVALID_SOCKET) {
             if (!CloseSocket(hListenSocket.socket)) {
                 LogPrintf("CloseSocket(hListenSocket) failed with error %s\n",
                           NetworkErrorString(WSAGetLastError()));
             }
         }
     }
 
     // clean up some globals (to help leak detection)
     for (CNode *pnode : vNodes) {
         DeleteNode(pnode);
     }
     for (CNode *pnode : vNodesDisconnected) {
         DeleteNode(pnode);
     }
     vNodes.clear();
     vNodesDisconnected.clear();
     vhListenSocket.clear();
     semOutbound.reset();
     semAddnode.reset();
 }
 
 void CConnman::DeleteNode(CNode *pnode) {
     assert(pnode);
     bool fUpdateConnectionTime = false;
     m_msgproc->FinalizeNode(*config, pnode->GetId(), fUpdateConnectionTime);
     if (fUpdateConnectionTime) {
         addrman.Connected(pnode->addr);
     }
     delete pnode;
 }
 
 CConnman::~CConnman() {
     Interrupt();
     Stop();
 }
 
 size_t CConnman::GetAddressCount() const {
     return addrman.size();
 }
 
 void CConnman::SetServices(const CService &addr, ServiceFlags nServices) {
     addrman.SetServices(addr, nServices);
 }
 
 void CConnman::MarkAddressGood(const CAddress &addr) {
     addrman.Good(addr);
 }
 
 void CConnman::AddNewAddresses(const std::vector<CAddress> &vAddr,
                                const CAddress &addrFrom, int64_t nTimePenalty) {
     addrman.Add(vAddr, addrFrom, nTimePenalty);
 }
 
 std::vector<CAddress> CConnman::GetAddresses() {
     return addrman.GetAddr();
 }
 
 bool CConnman::AddNode(const std::string &strNode) {
     LOCK(cs_vAddedNodes);
     for (const std::string &it : vAddedNodes) {
         if (strNode == it) {
             return false;
         }
     }
 
     vAddedNodes.push_back(strNode);
     return true;
 }
 
 bool CConnman::RemoveAddedNode(const std::string &strNode) {
     LOCK(cs_vAddedNodes);
     for (std::vector<std::string>::iterator it = vAddedNodes.begin();
          it != vAddedNodes.end(); ++it) {
         if (strNode == *it) {
             vAddedNodes.erase(it);
             return true;
         }
     }
     return false;
 }
 
 size_t CConnman::GetNodeCount(NumConnections flags) {
     LOCK(cs_vNodes);
     // Shortcut if we want total
     if (flags == CConnman::CONNECTIONS_ALL) {
         return vNodes.size();
     }
 
     int nNum = 0;
     for (const auto &pnode : vNodes) {
         if (flags & (pnode->fInbound ? CONNECTIONS_IN : CONNECTIONS_OUT)) {
             nNum++;
         }
     }
 
     return nNum;
 }
 
 void CConnman::GetNodeStats(std::vector<CNodeStats> &vstats) {
     vstats.clear();
     LOCK(cs_vNodes);
     vstats.reserve(vNodes.size());
     for (CNode *pnode : vNodes) {
         vstats.emplace_back();
         pnode->copyStats(vstats.back(), addrman.m_asmap);
     }
 }
 
 bool CConnman::DisconnectNode(const std::string &strNode) {
     LOCK(cs_vNodes);
     if (CNode *pnode = FindNode(strNode)) {
         pnode->fDisconnect = true;
         return true;
     }
     return false;
 }
 
 bool CConnman::DisconnectNode(const CSubNet &subnet) {
     bool disconnected = false;
     LOCK(cs_vNodes);
     for (CNode *pnode : vNodes) {
         if (subnet.Match(pnode->addr)) {
             pnode->fDisconnect = true;
             disconnected = true;
         }
     }
     return disconnected;
 }
 
 bool CConnman::DisconnectNode(const CNetAddr &addr) {
     return DisconnectNode(CSubNet(addr));
 }
 
 bool CConnman::DisconnectNode(NodeId id) {
     LOCK(cs_vNodes);
     for (CNode *pnode : vNodes) {
         if (id == pnode->GetId()) {
             pnode->fDisconnect = true;
             return true;
         }
     }
     return false;
 }
 
 void CConnman::RecordBytesRecv(uint64_t bytes) {
     LOCK(cs_totalBytesRecv);
     nTotalBytesRecv += bytes;
 }
 
 void CConnman::RecordBytesSent(uint64_t bytes) {
     LOCK(cs_totalBytesSent);
     nTotalBytesSent += bytes;
 
     uint64_t now = GetTime();
     if (nMaxOutboundCycleStartTime + nMaxOutboundTimeframe < now) {
         // timeframe expired, reset cycle
         nMaxOutboundCycleStartTime = now;
         nMaxOutboundTotalBytesSentInCycle = 0;
     }
 
     // TODO, exclude whitebind peers
     nMaxOutboundTotalBytesSentInCycle += bytes;
 }
 
 void CConnman::SetMaxOutboundTarget(uint64_t limit) {
     LOCK(cs_totalBytesSent);
     nMaxOutboundLimit = limit;
 }
 
 uint64_t CConnman::GetMaxOutboundTarget() {
     LOCK(cs_totalBytesSent);
     return nMaxOutboundLimit;
 }
 
 uint64_t CConnman::GetMaxOutboundTimeframe() {
     LOCK(cs_totalBytesSent);
     return nMaxOutboundTimeframe;
 }
 
 uint64_t CConnman::GetMaxOutboundTimeLeftInCycle() {
     LOCK(cs_totalBytesSent);
     if (nMaxOutboundLimit == 0) {
         return 0;
     }
 
     if (nMaxOutboundCycleStartTime == 0) {
         return nMaxOutboundTimeframe;
     }
 
     uint64_t cycleEndTime = nMaxOutboundCycleStartTime + nMaxOutboundTimeframe;
     uint64_t now = GetTime();
     return (cycleEndTime < now) ? 0 : cycleEndTime - GetTime();
 }
 
 void CConnman::SetMaxOutboundTimeframe(uint64_t timeframe) {
     LOCK(cs_totalBytesSent);
     if (nMaxOutboundTimeframe != timeframe) {
         // reset measure-cycle in case of changing the timeframe.
         nMaxOutboundCycleStartTime = GetTime();
     }
     nMaxOutboundTimeframe = timeframe;
 }
 
 bool CConnman::OutboundTargetReached(bool historicalBlockServingLimit) {
     LOCK(cs_totalBytesSent);
     if (nMaxOutboundLimit == 0) {
         return false;
     }
 
     if (historicalBlockServingLimit) {
         // keep a large enough buffer to at least relay each block once.
         uint64_t timeLeftInCycle = GetMaxOutboundTimeLeftInCycle();
         uint64_t buffer = timeLeftInCycle / 600 * ONE_MEGABYTE;
         if (buffer >= nMaxOutboundLimit ||
             nMaxOutboundTotalBytesSentInCycle >= nMaxOutboundLimit - buffer) {
             return true;
         }
     } else if (nMaxOutboundTotalBytesSentInCycle >= nMaxOutboundLimit) {
         return true;
     }
 
     return false;
 }
 
 uint64_t CConnman::GetOutboundTargetBytesLeft() {
     LOCK(cs_totalBytesSent);
     if (nMaxOutboundLimit == 0) {
         return 0;
     }
 
     return (nMaxOutboundTotalBytesSentInCycle >= nMaxOutboundLimit)
                ? 0
                : nMaxOutboundLimit - nMaxOutboundTotalBytesSentInCycle;
 }
 
 uint64_t CConnman::GetTotalBytesRecv() {
     LOCK(cs_totalBytesRecv);
     return nTotalBytesRecv;
 }
 
 uint64_t CConnman::GetTotalBytesSent() {
     LOCK(cs_totalBytesSent);
     return nTotalBytesSent;
 }
 
 ServiceFlags CConnman::GetLocalServices() const {
     return nLocalServices;
 }
 
 void CConnman::SetBestHeight(int height) {
     nBestHeight.store(height, std::memory_order_release);
 }
 
 int CConnman::GetBestHeight() const {
     return nBestHeight.load(std::memory_order_acquire);
 }
 
 unsigned int CConnman::GetReceiveFloodSize() const {
     return nReceiveFloodSize;
 }
 
 CNode::CNode(NodeId idIn, ServiceFlags nLocalServicesIn,
              int nMyStartingHeightIn, SOCKET hSocketIn, const CAddress &addrIn,
              uint64_t nKeyedNetGroupIn, uint64_t nLocalHostNonceIn,
              const CAddress &addrBindIn, const std::string &addrNameIn,
              bool fInboundIn, bool block_relay_only)
     : nTimeConnected(GetSystemTimeInSeconds()), addr(addrIn),
       addrBind(addrBindIn), fInbound(fInboundIn),
       nKeyedNetGroup(nKeyedNetGroupIn),
       // Don't relay addr messages to peers that we connect to as
       // block-relay-only peers (to prevent adversaries from inferring these
       // links from addr traffic).
       m_addr_known{block_relay_only
                        ? nullptr
                        : std::make_unique<CRollingBloomFilter>(5000, 0.001)},
       id(idIn), nLocalHostNonce(nLocalHostNonceIn),
       nLocalServices(nLocalServicesIn), nMyStartingHeight(nMyStartingHeightIn) {
     hSocket = hSocketIn;
     addrName = addrNameIn == "" ? addr.ToStringIPPort() : addrNameIn;
     hashContinue = BlockHash();
     if (!block_relay_only) {
         m_tx_relay = std::make_unique<TxRelay>();
     }
 
     for (const std::string &msg : getAllNetMessageTypes()) {
         mapRecvBytesPerMsgCmd[msg] = 0;
     }
     mapRecvBytesPerMsgCmd[NET_MESSAGE_COMMAND_OTHER] = 0;
 
     if (fLogIPs) {
         LogPrint(BCLog::NET, "Added connection to %s peer=%d\n", addrName, id);
     } else {
         LogPrint(BCLog::NET, "Added connection peer=%d\n", id);
     }
 
     m_deserializer = std::make_unique<V1TransportDeserializer>(
         V1TransportDeserializer(GetConfig().GetChainParams().NetMagic(),
                                 SER_NETWORK, INIT_PROTO_VERSION));
+    m_serializer =
+        std::make_unique<V1TransportSerializer>(V1TransportSerializer());
 }
 
 CNode::~CNode() {
     CloseSocket(hSocket);
 }
 
 bool CConnman::NodeFullyConnected(const CNode *pnode) {
     return pnode && pnode->fSuccessfullyConnected && !pnode->fDisconnect;
 }
 
 void CConnman::PushMessage(CNode *pnode, CSerializedNetMsg &&msg) {
     size_t nMessageSize = msg.data.size();
-    size_t nTotalSize = nMessageSize + CMessageHeader::HEADER_SIZE;
     LogPrint(BCLog::NET, "sending %s (%d bytes) peer=%d\n",
              SanitizeString(msg.command), nMessageSize, pnode->GetId());
 
+    // make sure we use the appropriate network transport format
     std::vector<uint8_t> serializedHeader;
-    serializedHeader.reserve(CMessageHeader::HEADER_SIZE);
-    uint256 hash = Hash(msg.data.data(), msg.data.data() + nMessageSize);
-    CMessageHeader hdr(config->GetChainParams().NetMagic(), msg.command.c_str(),
-                       nMessageSize);
-    memcpy(hdr.pchChecksum, hash.begin(), CMessageHeader::CHECKSUM_SIZE);
-
-    CVectorWriter{SER_NETWORK, INIT_PROTO_VERSION, serializedHeader, 0, hdr};
+    pnode->m_serializer->prepareForTransport(*config, msg, serializedHeader);
+    size_t nTotalSize = nMessageSize + serializedHeader.size();
 
     size_t nBytesSent = 0;
     {
         LOCK(pnode->cs_vSend);
         bool optimisticSend(pnode->vSendMsg.empty());
 
         // log total amount of bytes per command
         pnode->mapSendBytesPerMsgCmd[msg.command] += nTotalSize;
         pnode->nSendSize += nTotalSize;
 
         if (pnode->nSendSize > nSendBufferMaxSize) {
             pnode->fPauseSend = true;
         }
         pnode->vSendMsg.push_back(std::move(serializedHeader));
         if (nMessageSize) {
             pnode->vSendMsg.push_back(std::move(msg.data));
         }
 
         // If write queue empty, attempt "optimistic write"
         if (optimisticSend == true) {
             nBytesSent = SocketSendData(pnode);
         }
     }
     if (nBytesSent) {
         RecordBytesSent(nBytesSent);
     }
 }
 
 bool CConnman::ForNode(NodeId id, std::function<bool(CNode *pnode)> func) {
     CNode *found = nullptr;
     LOCK(cs_vNodes);
     for (auto &&pnode : vNodes) {
         if (pnode->GetId() == id) {
             found = pnode;
             break;
         }
     }
     return found != nullptr && NodeFullyConnected(found) && func(found);
 }
 
 int64_t CConnman::PoissonNextSendInbound(int64_t now,
                                          int average_interval_seconds) {
     if (m_next_send_inv_to_incoming < now) {
         // If this function were called from multiple threads simultaneously
         // it would be possible that both update the next send variable, and
         // return a different result to their caller. This is not possible in
         // practice as only the net processing thread invokes this function.
         m_next_send_inv_to_incoming =
             PoissonNextSend(now, average_interval_seconds);
     }
     return m_next_send_inv_to_incoming;
 }
 
 int64_t PoissonNextSend(int64_t now, int average_interval_seconds) {
     return now + int64_t(log1p(GetRand(1ULL << 48) *
                                -0.0000000000000035527136788 /* -1/2^48 */) *
                              average_interval_seconds * -1000000.0 +
                          0.5);
 }
 
 CSipHasher CConnman::GetDeterministicRandomizer(uint64_t id) const {
     return CSipHasher(nSeed0, nSeed1).Write(id);
 }
 
 uint64_t CConnman::CalculateKeyedNetGroup(const CAddress &ad) const {
     std::vector<uint8_t> vchNetGroup(ad.GetGroup(addrman.m_asmap));
 
     return GetDeterministicRandomizer(RANDOMIZER_ID_NETGROUP)
         .Write(vchNetGroup.data(), vchNetGroup.size())
         .Finalize();
 }
 
 /**
  * This function convert MaxBlockSize from byte to
  * MB with a decimal precision one digit rounded down
  * E.g.
  * 1660000 -> 1.6
  * 2010000 -> 2.0
  * 1000000 -> 1.0
  * 230000  -> 0.2
  * 50000   -> 0.0
  *
  *  NB behavior for EB<1MB not standardized yet still
  *  the function applies the same algo used for
  *  EB greater or equal to 1MB
  */
 std::string getSubVersionEB(uint64_t MaxBlockSize) {
     // Prepare EB string we are going to add to SubVer:
     // 1) translate from byte to MB and convert to string
     // 2) limit the EB string to the first decimal digit (floored)
     std::stringstream ebMBs;
     ebMBs << (MaxBlockSize / (ONE_MEGABYTE / 10));
     std::string eb = ebMBs.str();
     eb.insert(eb.size() - 1, ".", 1);
     if (eb.substr(0, 1) == ".") {
         eb = "0" + eb;
     }
     return eb;
 }
 
 std::string userAgent(const Config &config) {
     // format excessive blocksize value
     std::string eb = getSubVersionEB(config.GetMaxBlockSize());
     std::vector<std::string> uacomments;
     uacomments.push_back("EB" + eb);
 
     // Comments are checked for char compliance at startup, it is safe to add
     // them to the user agent string
     for (const std::string &cmt : gArgs.GetArgs("-uacomment")) {
         uacomments.push_back(cmt);
     }
 
     // Size compliance is checked at startup, it is safe to not check it again
     std::string subversion =
         FormatSubVersion(CLIENT_NAME, CLIENT_VERSION, uacomments);
 
     return subversion;
 }
diff --git a/src/net.h b/src/net.h
index 89b14945b..7f7f51823 100644
--- a/src/net.h
+++ b/src/net.h
@@ -1,1061 +1,1081 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2019 The Bitcoin Core developers
 // Copyright (c) 2017-2019 The Bitcoin developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #ifndef BITCOIN_NET_H
 #define BITCOIN_NET_H
 
 #include <addrdb.h>
 #include <addrman.h>
 #include <amount.h>
 #include <bloom.h>
 #include <chainparams.h>
 #include <compat.h>
 #include <crypto/siphash.h>
 #include <hash.h>
 #include <limitedmap.h>
 #include <net_permissions.h>
 #include <netaddress.h>
 #include <protocol.h>
 #include <random.h>
 #include <streams.h>
 #include <sync.h>
 #include <threadinterrupt.h>
 #include <uint256.h>
 
 #include <atomic>
 #include <condition_variable>
 #include <cstdint>
 #include <deque>
 #include <memory>
 #include <thread>
 
 #ifndef WIN32
 #include <arpa/inet.h>
 #endif
 
 class BanMan;
 class Config;
 class CNode;
 class CScheduler;
 struct bilingual_str;
 
 /** Default for -whitelistrelay. */
 static const bool DEFAULT_WHITELISTRELAY = true;
 /** Default for -whitelistforcerelay. */
 static const bool DEFAULT_WHITELISTFORCERELAY = false;
 
 /**
  * Time between pings automatically sent out for latency probing and keepalive
  * (in seconds).
  */
 static const int PING_INTERVAL = 2 * 60;
 /**
  * Time after which to disconnect, after waiting for a ping response (or
  * inactivity).
  */
 static const int TIMEOUT_INTERVAL = 20 * 60;
 /** Run the feeler connection loop once every 2 minutes or 120 seconds. **/
 static const int FEELER_INTERVAL = 120;
 /** The maximum number of entries in an 'inv' protocol message */
 static const unsigned int MAX_INV_SZ = 50000;
 static_assert(MAX_PROTOCOL_MESSAGE_LENGTH > MAX_INV_SZ * sizeof(CInv),
               "Max protocol message length must be greater than largest "
               "possible INV message");
 /** The maximum number of entries in a locator */
 static const unsigned int MAX_LOCATOR_SZ = 101;
 /** The maximum number of new addresses to accumulate before announcing. */
 static const unsigned int MAX_ADDR_TO_SEND = 1000;
 /** Maximum length of the user agent string in `version` message */
 static const unsigned int MAX_SUBVERSION_LENGTH = 256;
 /**
  * Maximum number of automatic outgoing nodes over which we'll relay everything
  * (blocks, tx, addrs, etc)
  */
 static const int MAX_OUTBOUND_FULL_RELAY_CONNECTIONS = 8;
 /** Maximum number of addnode outgoing nodes */
 static const int MAX_ADDNODE_CONNECTIONS = 8;
 /** Maximum number of block-relay-only outgoing connections */
 static const int MAX_BLOCKS_ONLY_CONNECTIONS = 2;
 /** -listen default */
 static const bool DEFAULT_LISTEN = true;
 /** -upnp default */
 #ifdef USE_UPNP
 static const bool DEFAULT_UPNP = USE_UPNP;
 #else
 static const bool DEFAULT_UPNP = false;
 #endif
 /** The maximum number of peer connections to maintain. */
 static const unsigned int DEFAULT_MAX_PEER_CONNECTIONS = 125;
 /** The default for -maxuploadtarget. 0 = Unlimited */
 static const uint64_t DEFAULT_MAX_UPLOAD_TARGET = 0;
 /** The default timeframe for -maxuploadtarget. 1 day. */
 static const uint64_t MAX_UPLOAD_TIMEFRAME = 60 * 60 * 24;
 /** Default for blocks only*/
 static const bool DEFAULT_BLOCKSONLY = false;
 /** -peertimeout default */
 static const int64_t DEFAULT_PEER_CONNECT_TIMEOUT = 60;
 
 static const bool DEFAULT_FORCEDNSSEED = false;
 static const size_t DEFAULT_MAXRECEIVEBUFFER = 5 * 1000;
 static const size_t DEFAULT_MAXSENDBUFFER = 1 * 1000;
 
 typedef int64_t NodeId;
 
 /**
  * Special NodeId that represent no node.
  */
 static constexpr NodeId NO_NODE = -1;
 
 struct AddedNodeInfo {
     std::string strAddedNode;
     CService resolvedAddress;
     bool fConnected;
     bool fInbound;
 };
 
 struct CNodeStats;
 class CClientUIInterface;
 
 struct CSerializedNetMsg {
     CSerializedNetMsg() = default;
     CSerializedNetMsg(CSerializedNetMsg &&) = default;
     CSerializedNetMsg &operator=(CSerializedNetMsg &&) = default;
     // No copying, only moves.
     CSerializedNetMsg(const CSerializedNetMsg &msg) = delete;
     CSerializedNetMsg &operator=(const CSerializedNetMsg &) = delete;
 
     std::vector<uint8_t> data;
     std::string command;
 };
 
 namespace {
 struct CConnmanTest;
 }
 
 class NetEventsInterface;
 class CConnman {
 public:
     enum NumConnections {
         CONNECTIONS_NONE = 0,
         CONNECTIONS_IN = (1U << 0),
         CONNECTIONS_OUT = (1U << 1),
         CONNECTIONS_ALL = (CONNECTIONS_IN | CONNECTIONS_OUT),
     };
 
     struct Options {
         ServiceFlags nLocalServices = NODE_NONE;
         int nMaxConnections = 0;
         int m_max_outbound_full_relay = 0;
         int m_max_outbound_block_relay = 0;
         int nMaxAddnode = 0;
         int nMaxFeeler = 0;
         int nBestHeight = 0;
         CClientUIInterface *uiInterface = nullptr;
         NetEventsInterface *m_msgproc = nullptr;
         BanMan *m_banman = nullptr;
         unsigned int nSendBufferMaxSize = 0;
         unsigned int nReceiveFloodSize = 0;
         uint64_t nMaxOutboundTimeframe = 0;
         uint64_t nMaxOutboundLimit = 0;
         int64_t m_peer_connect_timeout = DEFAULT_PEER_CONNECT_TIMEOUT;
         std::vector<std::string> vSeedNodes;
         std::vector<NetWhitelistPermissions> vWhitelistedRange;
         std::vector<NetWhitebindPermissions> vWhiteBinds;
         std::vector<CService> vBinds;
         bool m_use_addrman_outgoing = true;
         std::vector<std::string> m_specified_outgoing;
         std::vector<std::string> m_added_nodes;
         std::vector<bool> m_asmap;
     };
 
     void Init(const Options &connOptions) {
         nLocalServices = connOptions.nLocalServices;
         nMaxConnections = connOptions.nMaxConnections;
         m_max_outbound_full_relay = std::min(
             connOptions.m_max_outbound_full_relay, connOptions.nMaxConnections);
         m_max_outbound_block_relay = connOptions.m_max_outbound_block_relay;
         m_use_addrman_outgoing = connOptions.m_use_addrman_outgoing;
         nMaxAddnode = connOptions.nMaxAddnode;
         nMaxFeeler = connOptions.nMaxFeeler;
         m_max_outbound =
             m_max_outbound_full_relay + m_max_outbound_block_relay + nMaxFeeler;
         nBestHeight = connOptions.nBestHeight;
         clientInterface = connOptions.uiInterface;
         m_banman = connOptions.m_banman;
         m_msgproc = connOptions.m_msgproc;
         nSendBufferMaxSize = connOptions.nSendBufferMaxSize;
         nReceiveFloodSize = connOptions.nReceiveFloodSize;
         m_peer_connect_timeout = connOptions.m_peer_connect_timeout;
         {
             LOCK(cs_totalBytesSent);
             nMaxOutboundTimeframe = connOptions.nMaxOutboundTimeframe;
             nMaxOutboundLimit = connOptions.nMaxOutboundLimit;
         }
         vWhitelistedRange = connOptions.vWhitelistedRange;
         {
             LOCK(cs_vAddedNodes);
             vAddedNodes = connOptions.m_added_nodes;
         }
     }
 
     CConnman(const Config &configIn, uint64_t seed0, uint64_t seed1);
     ~CConnman();
 
     bool Start(CScheduler &scheduler, const Options &options);
 
     // TODO: Remove NO_THREAD_SAFETY_ANALYSIS. Lock cs_vNodes before reading the
     // variable vNodes.
     //
     // When removing NO_THREAD_SAFETY_ANALYSIS be aware of the following lock
     // order requirements:
     // * CheckForStaleTipAndEvictPeers locks cs_main before indirectly calling
     //   GetExtraOutboundCount which locks cs_vNodes.
     // * ProcessMessage locks cs_main and g_cs_orphans before indirectly calling
     //   ForEachNode which locks cs_vNodes.
     //
     // Thus the implicit locking order requirement is: (1) cs_main, (2)
     // g_cs_orphans, (3) cs_vNodes.
     void Stop() NO_THREAD_SAFETY_ANALYSIS;
 
     void Interrupt();
     bool GetNetworkActive() const { return fNetworkActive; };
     bool GetUseAddrmanOutgoing() const { return m_use_addrman_outgoing; };
     void SetNetworkActive(bool active);
     void OpenNetworkConnection(const CAddress &addrConnect, bool fCountFailure,
                                CSemaphoreGrant *grantOutbound = nullptr,
                                const char *strDest = nullptr,
                                bool fOneShot = false, bool fFeeler = false,
                                bool manual_connection = false,
                                bool block_relay_only = false);
     bool CheckIncomingNonce(uint64_t nonce);
 
     bool ForNode(NodeId id, std::function<bool(CNode *pnode)> func);
 
     void PushMessage(CNode *pnode, CSerializedNetMsg &&msg);
 
     template <typename Callable> void ForEachNode(Callable &&func) {
         LOCK(cs_vNodes);
         for (auto &&node : vNodes) {
             if (NodeFullyConnected(node)) {
                 func(node);
             }
         }
     };
 
     template <typename Callable> void ForEachNode(Callable &&func) const {
         LOCK(cs_vNodes);
         for (auto &&node : vNodes) {
             if (NodeFullyConnected(node)) {
                 func(node);
             }
         }
     };
 
     template <typename Callable, typename CallableAfter>
     void ForEachNodeThen(Callable &&pre, CallableAfter &&post) {
         LOCK(cs_vNodes);
         for (auto &&node : vNodes) {
             if (NodeFullyConnected(node)) {
                 pre(node);
             }
         }
         post();
     };
 
     template <typename Callable, typename CallableAfter>
     void ForEachNodeThen(Callable &&pre, CallableAfter &&post) const {
         LOCK(cs_vNodes);
         for (auto &&node : vNodes) {
             if (NodeFullyConnected(node)) {
                 pre(node);
             }
         }
         post();
     };
 
     // Addrman functions
     size_t GetAddressCount() const;
     void SetServices(const CService &addr, ServiceFlags nServices);
     void MarkAddressGood(const CAddress &addr);
     void AddNewAddresses(const std::vector<CAddress> &vAddr,
                          const CAddress &addrFrom, int64_t nTimePenalty = 0);
     std::vector<CAddress> GetAddresses();
 
     // This allows temporarily exceeding m_max_outbound_full_relay, with the
     // goal of finding a peer that is better than all our current peers.
     void SetTryNewOutboundPeer(bool flag);
     bool GetTryNewOutboundPeer();
 
     // Return the number of outbound peers we have in excess of our target (eg,
     // if we previously called SetTryNewOutboundPeer(true), and have since set
     // to false, we may have extra peers that we wish to disconnect). This may
     // return a value less than (num_outbound_connections - num_outbound_slots)
     // in cases where some outbound connections are not yet fully connected, or
     // not yet fully disconnected.
     int GetExtraOutboundCount();
 
     bool AddNode(const std::string &node);
     bool RemoveAddedNode(const std::string &node);
     std::vector<AddedNodeInfo> GetAddedNodeInfo();
 
     size_t GetNodeCount(NumConnections num);
     void GetNodeStats(std::vector<CNodeStats> &vstats);
     bool DisconnectNode(const std::string &node);
     bool DisconnectNode(const CSubNet &subnet);
     bool DisconnectNode(const CNetAddr &addr);
     bool DisconnectNode(NodeId id);
 
     //! Used to convey which local services we are offering peers during node
     //! connection.
     //!
     //! The data returned by this is used in CNode construction,
     //! which is used to advertise which services we are offering
     //! that peer during `net_processing.cpp:PushNodeVersion()`.
     ServiceFlags GetLocalServices() const;
 
     //! set the max outbound target in bytes.
     void SetMaxOutboundTarget(uint64_t limit);
     uint64_t GetMaxOutboundTarget();
 
     //! set the timeframe for the max outbound target.
     void SetMaxOutboundTimeframe(uint64_t timeframe);
     uint64_t GetMaxOutboundTimeframe();
 
     //! check if the outbound target is reached. If param
     //! historicalBlockServingLimit is set true, the function will response true
     //! if the limit for serving historical blocks has been reached.
     bool OutboundTargetReached(bool historicalBlockServingLimit);
 
     //! response the bytes left in the current max outbound cycle in case of no
     //! limit, it will always response 0
     uint64_t GetOutboundTargetBytesLeft();
 
     //! response the time in second left in the current max outbound cycle in
     //! case of no limit, it will always response 0
     uint64_t GetMaxOutboundTimeLeftInCycle();
 
     uint64_t GetTotalBytesRecv();
     uint64_t GetTotalBytesSent();
 
     void SetBestHeight(int height);
     int GetBestHeight() const;
 
     /** Get a unique deterministic randomizer. */
     CSipHasher GetDeterministicRandomizer(uint64_t id) const;
 
     unsigned int GetReceiveFloodSize() const;
 
     void WakeMessageHandler();
 
     /**
      * Attempts to obfuscate tx time through exponentially distributed emitting.
      * Works assuming that a single interval is used.
      * Variable intervals will result in privacy decrease.
      */
     int64_t PoissonNextSendInbound(int64_t now, int average_interval_seconds);
 
     void SetAsmap(std::vector<bool> asmap) {
         addrman.m_asmap = std::move(asmap);
     }
 
 private:
     struct ListenSocket {
     public:
         SOCKET socket;
         inline void AddSocketPermissionFlags(NetPermissionFlags &flags) const {
             NetPermissions::AddFlag(flags, m_permissions);
         }
         ListenSocket(SOCKET socket_, NetPermissionFlags permissions_)
             : socket(socket_), m_permissions(permissions_) {}
 
     private:
         NetPermissionFlags m_permissions;
     };
 
     bool BindListenPort(const CService &bindAddr, bilingual_str &strError,
                         NetPermissionFlags permissions);
     bool Bind(const CService &addr, unsigned int flags,
               NetPermissionFlags permissions);
     bool InitBinds(const std::vector<CService> &binds,
                    const std::vector<NetWhitebindPermissions> &whiteBinds);
     void ThreadOpenAddedConnections();
     void AddOneShot(const std::string &strDest);
     void ProcessOneShot();
     void ThreadOpenConnections(std::vector<std::string> connect);
     void ThreadMessageHandler();
     void AcceptConnection(const ListenSocket &hListenSocket);
     void DisconnectNodes();
     void NotifyNumConnectionsChanged();
     void InactivityCheck(CNode *pnode);
     bool GenerateSelectSet(std::set<SOCKET> &recv_set,
                            std::set<SOCKET> &send_set,
                            std::set<SOCKET> &error_set);
     void SocketEvents(std::set<SOCKET> &recv_set, std::set<SOCKET> &send_set,
                       std::set<SOCKET> &error_set);
     void SocketHandler();
     void ThreadSocketHandler();
     void ThreadDNSAddressSeed();
 
     uint64_t CalculateKeyedNetGroup(const CAddress &ad) const;
 
     CNode *FindNode(const CNetAddr &ip);
     CNode *FindNode(const CSubNet &subNet);
     CNode *FindNode(const std::string &addrName);
     CNode *FindNode(const CService &addr);
 
     bool AttemptToEvictConnection();
     CNode *ConnectNode(CAddress addrConnect, const char *pszDest,
                        bool fCountFailure, bool manual_connection,
                        bool block_relay_only);
     void AddWhitelistPermissionFlags(NetPermissionFlags &flags,
                                      const CNetAddr &addr) const;
 
     void DeleteNode(CNode *pnode);
 
     NodeId GetNewNodeId();
 
     size_t SocketSendData(CNode *pnode) const;
     void DumpAddresses();
 
     // Network stats
     void RecordBytesRecv(uint64_t bytes);
     void RecordBytesSent(uint64_t bytes);
 
     // Whether the node should be passed out in ForEach* callbacks
     static bool NodeFullyConnected(const CNode *pnode);
 
     const Config *config;
 
     // Network usage totals
     RecursiveMutex cs_totalBytesRecv;
     RecursiveMutex cs_totalBytesSent;
     uint64_t nTotalBytesRecv GUARDED_BY(cs_totalBytesRecv);
     uint64_t nTotalBytesSent GUARDED_BY(cs_totalBytesSent);
 
     // outbound limit & stats
     uint64_t nMaxOutboundTotalBytesSentInCycle GUARDED_BY(cs_totalBytesSent);
     uint64_t nMaxOutboundCycleStartTime GUARDED_BY(cs_totalBytesSent);
     uint64_t nMaxOutboundLimit GUARDED_BY(cs_totalBytesSent);
     uint64_t nMaxOutboundTimeframe GUARDED_BY(cs_totalBytesSent);
 
     // P2P timeout in seconds
     int64_t m_peer_connect_timeout;
 
     // Whitelisted ranges. Any node connecting from these is automatically
     // whitelisted (as well as those connecting to whitelisted binds).
     std::vector<NetWhitelistPermissions> vWhitelistedRange;
 
     unsigned int nSendBufferMaxSize{0};
     unsigned int nReceiveFloodSize{0};
 
     std::vector<ListenSocket> vhListenSocket;
     std::atomic<bool> fNetworkActive{true};
     bool fAddressesInitialized{false};
     CAddrMan addrman;
     std::deque<std::string> vOneShots GUARDED_BY(cs_vOneShots);
     RecursiveMutex cs_vOneShots;
     std::vector<std::string> vAddedNodes GUARDED_BY(cs_vAddedNodes);
     RecursiveMutex cs_vAddedNodes;
     std::vector<CNode *> vNodes GUARDED_BY(cs_vNodes);
     std::list<CNode *> vNodesDisconnected;
     mutable RecursiveMutex cs_vNodes;
     std::atomic<NodeId> nLastNodeId{0};
     unsigned int nPrevNodeCount{0};
 
     /**
      * Services this instance offers.
      *
      * This data is replicated in each CNode instance we create during peer
      * connection (in ConnectNode()) under a member also called
      * nLocalServices.
      *
      * This data is not marked const, but after being set it should not
      * change. See the note in CNode::nLocalServices documentation.
      *
      * \sa CNode::nLocalServices
      */
     ServiceFlags nLocalServices;
 
     std::unique_ptr<CSemaphore> semOutbound;
     std::unique_ptr<CSemaphore> semAddnode;
     int nMaxConnections;
 
     // How many full-relay (tx, block, addr) outbound peers we want
     int m_max_outbound_full_relay;
 
     // How many block-relay only outbound peers we want
     // We do not relay tx or addr messages with these peers
     int m_max_outbound_block_relay;
 
     int nMaxAddnode;
     int nMaxFeeler;
     int m_max_outbound;
     bool m_use_addrman_outgoing;
     std::atomic<int> nBestHeight;
     CClientUIInterface *clientInterface;
     NetEventsInterface *m_msgproc;
     BanMan *m_banman;
 
     /** SipHasher seeds for deterministic randomness */
     const uint64_t nSeed0, nSeed1;
 
     /** flag for waking the message processor. */
     bool fMsgProcWake GUARDED_BY(mutexMsgProc);
 
     std::condition_variable condMsgProc;
     Mutex mutexMsgProc;
     std::atomic<bool> flagInterruptMsgProc{false};
 
     CThreadInterrupt interruptNet;
 
     std::thread threadDNSAddressSeed;
     std::thread threadSocketHandler;
     std::thread threadOpenAddedConnections;
     std::thread threadOpenConnections;
     std::thread threadMessageHandler;
 
     /**
      * flag for deciding to connect to an extra outbound peer, in excess of
      * m_max_outbound_full_relay. This takes the place of a feeler connection.
      */
     std::atomic_bool m_try_another_outbound_peer;
 
     std::atomic<int64_t> m_next_send_inv_to_incoming{0};
 
     friend struct ::CConnmanTest;
 };
 
 void Discover();
 void StartMapPort();
 void InterruptMapPort();
 void StopMapPort();
 unsigned short GetListenPort();
 
 /**
  * Interface for message handling
  */
 class NetEventsInterface {
 public:
     virtual bool ProcessMessages(const Config &config, CNode *pnode,
                                  std::atomic<bool> &interrupt) = 0;
     virtual bool SendMessages(const Config &config, CNode *pnode,
                               std::atomic<bool> &interrupt) = 0;
     virtual void InitializeNode(const Config &config, CNode *pnode) = 0;
     virtual void FinalizeNode(const Config &config, NodeId id,
                               bool &update_connection_time) = 0;
 
 protected:
     /**
      * Protected destructor so that instances can only be deleted by derived
      * classes. If that restriction is no longer desired, this should be made
      * public and virtual.
      */
     ~NetEventsInterface() = default;
 };
 
 enum {
     // unknown
     LOCAL_NONE,
     // address a local interface listens on
     LOCAL_IF,
     // address explicit bound to
     LOCAL_BIND,
     // address reported by UPnP
     LOCAL_UPNP,
     // address explicitly specified (-externalip=)
     LOCAL_MANUAL,
 
     LOCAL_MAX
 };
 
 bool IsPeerAddrLocalGood(CNode *pnode);
 void AdvertiseLocal(CNode *pnode);
 
 /**
  * Mark a network as reachable or unreachable (no automatic connects to it)
  * @note Networks are reachable by default
  */
 void SetReachable(enum Network net, bool reachable);
 /** @returns true if the network is reachable, false otherwise */
 bool IsReachable(enum Network net);
 /** @returns true if the address is in a reachable network, false otherwise */
 bool IsReachable(const CNetAddr &addr);
 
 bool AddLocal(const CService &addr, int nScore = LOCAL_NONE);
 bool AddLocal(const CNetAddr &addr, int nScore = LOCAL_NONE);
 void RemoveLocal(const CService &addr);
 bool SeenLocal(const CService &addr);
 bool IsLocal(const CService &addr);
 bool GetLocal(CService &addr, const CNetAddr *paddrPeer = nullptr);
 CAddress GetLocalAddress(const CNetAddr *paddrPeer,
                          ServiceFlags nLocalServices);
 
 extern bool fDiscover;
 extern bool fListen;
 extern bool g_relay_txes;
 
 struct LocalServiceInfo {
     int nScore;
     int nPort;
 };
 
 extern RecursiveMutex cs_mapLocalHost;
 extern std::map<CNetAddr, LocalServiceInfo>
     mapLocalHost GUARDED_BY(cs_mapLocalHost);
 
 extern const std::string NET_MESSAGE_COMMAND_OTHER;
 // Command, total bytes
 typedef std::map<std::string, uint64_t> mapMsgCmdSize;
 
 /**
  * POD that contains various stats about a node.
  * Usually constructed from CConman::GetNodeStats. Stats are filled from the
  * node using CNode::copyStats.
  */
 struct CNodeStats {
     NodeId nodeid;
     ServiceFlags nServices;
     bool fRelayTxes;
     int64_t nLastSend;
     int64_t nLastRecv;
     int64_t nTimeConnected;
     int64_t nTimeOffset;
     std::string addrName;
     int nVersion;
     std::string cleanSubVer;
     bool fInbound;
     bool m_manual_connection;
     int nStartingHeight;
     uint64_t nSendBytes;
     mapMsgCmdSize mapSendBytesPerMsgCmd;
     uint64_t nRecvBytes;
     mapMsgCmdSize mapRecvBytesPerMsgCmd;
     NetPermissionFlags m_permissionFlags;
     bool m_legacyWhitelisted;
     int64_t m_ping_usec;
     int64_t m_ping_wait_usec;
     int64_t m_min_ping_usec;
     Amount minFeeFilter;
     // Our address, as reported by the peer
     std::string addrLocal;
     // Address of this peer
     CAddress addr;
     // Bind address of our side of the connection
     CAddress addrBind;
     uint32_t m_mapped_as;
 };
 
 /**
  * Transport protocol agnostic message container.
  * Ideally it should only contain receive time, payload,
  * command and size.
  */
 class CNetMessage {
 public:
     // received message data
     CDataStream m_recv;
     // time (in microseconds) of message receipt.
     int64_t m_time = 0;
     bool m_valid_netmagic = false;
     bool m_valid_header = false;
     bool m_valid_checksum = false;
     // size of the payload
     uint32_t m_message_size = 0;
     // used wire size of the message (including header/checksum)
     uint32_t m_raw_message_size = 0;
     std::string m_command;
 
     CNetMessage(CDataStream &&recv_in) : m_recv(std::move(recv_in)) {}
 
     void SetVersion(int nVersionIn) { m_recv.SetVersion(nVersionIn); }
 };
 
 /**
  * The TransportDeserializer takes care of holding and deserializing the
  * network receive buffer. It can deserialize the network buffer into a
  * transport protocol agnostic CNetMessage (command & payload)
  */
 class TransportDeserializer {
 public:
     // returns true if the current deserialization is complete
     virtual bool Complete() const = 0;
     // set the serialization context version
     virtual void SetVersion(int version) = 0;
     // read and deserialize data
     virtual int Read(const Config &config, const char *data,
                      uint32_t bytes) = 0;
     // decomposes a message from the context
     virtual CNetMessage GetMessage(const Config &config, int64_t time) = 0;
     virtual ~TransportDeserializer() {}
 };
 
 class V1TransportDeserializer final : public TransportDeserializer {
 private:
     mutable CHash256 hasher;
     mutable uint256 data_hash;
 
     // Parsing header (false) or data (true)
     bool in_data;
     // Partially received header.
     CDataStream hdrbuf;
     // Complete header.
     CMessageHeader hdr;
     // Received message data.
     CDataStream vRecv;
     uint32_t nHdrPos;
     uint32_t nDataPos;
 
     const uint256 &GetMessageHash() const;
     int readHeader(const Config &config, const char *pch, uint32_t nBytes);
     int readData(const char *pch, uint32_t nBytes);
 
     void Reset() {
         vRecv.clear();
         hdrbuf.clear();
         hdrbuf.resize(24);
         in_data = false;
         nHdrPos = 0;
         nDataPos = 0;
         data_hash.SetNull();
         hasher.Reset();
     }
 
 public:
     V1TransportDeserializer(
         const CMessageHeader::MessageMagic &pchMessageStartIn, int nTypeIn,
         int nVersionIn)
         : hdrbuf(nTypeIn, nVersionIn), hdr(pchMessageStartIn),
           vRecv(nTypeIn, nVersionIn) {
         Reset();
     }
 
     bool Complete() const override {
         if (!in_data) {
             return false;
         }
 
         return (hdr.nMessageSize == nDataPos);
     }
 
     void SetVersion(int nVersionIn) override {
         hdrbuf.SetVersion(nVersionIn);
         vRecv.SetVersion(nVersionIn);
     }
     int Read(const Config &config, const char *pch, uint32_t nBytes) override {
         int ret =
             in_data ? readData(pch, nBytes) : readHeader(config, pch, nBytes);
         if (ret < 0) {
             Reset();
         }
         return ret;
     }
 
     CNetMessage GetMessage(const Config &config, int64_t time) override;
 };
 
+/**
+ * The TransportSerializer prepares messages for the network transport
+ */
+class TransportSerializer {
+public:
+    // prepare message for transport (header construction, error-correction
+    // computation, payload encryption, etc.)
+    virtual void prepareForTransport(const Config &config,
+                                     CSerializedNetMsg &msg,
+                                     std::vector<uint8_t> &header) = 0;
+    virtual ~TransportSerializer() {}
+};
+
+class V1TransportSerializer : public TransportSerializer {
+public:
+    void prepareForTransport(const Config &config, CSerializedNetMsg &msg,
+                             std::vector<uint8_t> &header) override;
+};
+
 /** Information about a peer */
 class CNode {
     friend class CConnman;
 
 public:
     std::unique_ptr<TransportDeserializer> m_deserializer;
+    std::unique_ptr<TransportSerializer> m_serializer;
 
     // socket
     std::atomic<ServiceFlags> nServices{NODE_NONE};
     SOCKET hSocket GUARDED_BY(cs_hSocket);
     // Total size of all vSendMsg entries.
     size_t nSendSize{0};
     // Offset inside the first vSendMsg already sent.
     size_t nSendOffset{0};
     uint64_t nSendBytes GUARDED_BY(cs_vSend){0};
     std::deque<std::vector<uint8_t>> vSendMsg GUARDED_BY(cs_vSend);
     RecursiveMutex cs_vSend;
     RecursiveMutex cs_hSocket;
     RecursiveMutex cs_vRecv;
 
     RecursiveMutex cs_vProcessMsg;
     std::list<CNetMessage> vProcessMsg GUARDED_BY(cs_vProcessMsg);
     size_t nProcessQueueSize{0};
 
     RecursiveMutex cs_sendProcessing;
 
     std::deque<CInv> vRecvGetData;
     uint64_t nRecvBytes GUARDED_BY(cs_vRecv){0};
     std::atomic<int> nRecvVersion{INIT_PROTO_VERSION};
 
     std::atomic<int64_t> nLastSend{0};
     std::atomic<int64_t> nLastRecv{0};
     const int64_t nTimeConnected;
     std::atomic<int64_t> nTimeOffset{0};
     // Address of this peer
     const CAddress addr;
     // Bind address of our side of the connection
     const CAddress addrBind;
     std::atomic<int> nVersion{0};
     RecursiveMutex cs_SubVer;
     /**
      * cleanSubVer is a sanitized string of the user agent byte array we read
      * from the wire. This cleaned string can safely be logged or displayed.
      */
     std::string cleanSubVer GUARDED_BY(cs_SubVer){};
     // This peer is preferred for eviction.
     bool m_prefer_evict{false};
     bool HasPermission(NetPermissionFlags permission) const {
         return NetPermissions::HasFlag(m_permissionFlags, permission);
     }
     // This boolean is unusued in actual processing, only present for backward
     // compatibility at RPC/QT level
     bool m_legacyWhitelisted{false};
     // If true this node is being used as a short lived feeler.
     bool fFeeler{false};
     bool fOneShot{false};
     bool m_manual_connection{false};
     // set by version message
     bool fClient{false};
     // after BIP159, set by version message
     bool m_limited_node{false};
     const bool fInbound;
     std::atomic_bool fSuccessfullyConnected{false};
     // Setting fDisconnect to true will cause the node to be disconnected the
     // next time DisconnectNodes() runs
     std::atomic_bool fDisconnect{false};
     bool fSentAddr{false};
     CSemaphoreGrant grantOutbound;
     std::atomic<int> nRefCount{0};
 
     const uint64_t nKeyedNetGroup;
     std::atomic_bool fPauseRecv{false};
     std::atomic_bool fPauseSend{false};
 
 protected:
     mapMsgCmdSize mapSendBytesPerMsgCmd;
     mapMsgCmdSize mapRecvBytesPerMsgCmd GUARDED_BY(cs_vRecv);
 
 public:
     BlockHash hashContinue;
     std::atomic<int> nStartingHeight{-1};
 
     // flood relay
     std::vector<CAddress> vAddrToSend;
     const std::unique_ptr<CRollingBloomFilter> m_addr_known;
     bool fGetAddr{false};
     int64_t nNextAddrSend GUARDED_BY(cs_sendProcessing){0};
     int64_t nNextLocalAddrSend GUARDED_BY(cs_sendProcessing){0};
 
     bool IsAddrRelayPeer() const { return m_addr_known != nullptr; }
 
     // List of block ids we still have to announce.
     // There is no final sorting before sending, as they are always sent
     // immediately and in the order requested.
     std::vector<BlockHash> vInventoryBlockToSend GUARDED_BY(cs_inventory);
     RecursiveMutex cs_inventory;
 
     struct TxRelay {
         TxRelay() { pfilter = std::make_unique<CBloomFilter>(); }
         mutable RecursiveMutex cs_filter;
         // We use fRelayTxes for two purposes -
         // a) it allows us to not relay tx invs before receiving the peer's
         //    version message.
         // b) the peer may tell us in its version message that we should not
         //    relay tx invs unless it loads a bloom filter.
         bool fRelayTxes GUARDED_BY(cs_filter){false};
         std::unique_ptr<CBloomFilter> pfilter PT_GUARDED_BY(cs_filter)
             GUARDED_BY(cs_filter);
 
         mutable RecursiveMutex cs_tx_inventory;
         CRollingBloomFilter filterInventoryKnown GUARDED_BY(cs_tx_inventory){
             50000, 0.000001};
         // Set of transaction ids we still have to announce.
         // They are sorted by the mempool before relay, so the order is not
         // important.
         std::set<TxId> setInventoryTxToSend;
         // Used for BIP35 mempool sending
         bool fSendMempool GUARDED_BY(cs_tx_inventory){false};
         // Last time a "MEMPOOL" request was serviced.
         std::atomic<std::chrono::seconds> m_last_mempool_req{
             std::chrono::seconds{0}};
         std::chrono::microseconds nNextInvSend{0};
 
         RecursiveMutex cs_feeFilter;
         // Minimum fee rate with which to filter inv's to this node
         Amount minFeeFilter GUARDED_BY(cs_feeFilter){Amount::zero()};
         Amount lastSentFeeFilter{Amount::zero()};
         int64_t nextSendTimeFeeFilter{0};
     };
 
     // m_tx_relay == nullptr if we're not relaying transactions with this peer
     std::unique_ptr<TxRelay> m_tx_relay;
 
     // Used for headers announcements - unfiltered blocks to relay
     std::vector<BlockHash> vBlockHashesToAnnounce GUARDED_BY(cs_inventory);
 
     // Block and TXN accept times
     std::atomic<int64_t> nLastBlockTime{0};
     std::atomic<int64_t> nLastTXTime{0};
 
     // Ping time measurement:
     // The pong reply we're expecting, or 0 if no pong expected.
     std::atomic<uint64_t> nPingNonceSent{0};
     // Time (in usec) the last ping was sent, or 0 if no ping was ever sent.
     std::atomic<int64_t> nPingUsecStart{0};
     // Last measured round-trip time.
     std::atomic<int64_t> nPingUsecTime{0};
     // Best measured round-trip time.
     std::atomic<int64_t> nMinPingUsecTime{std::numeric_limits<int64_t>::max()};
     // Whether a ping is requested.
     std::atomic<bool> fPingQueued{false};
 
     std::set<TxId> orphan_work_set;
 
     CNode(NodeId id, ServiceFlags nLocalServicesIn, int nMyStartingHeightIn,
           SOCKET hSocketIn, const CAddress &addrIn, uint64_t nKeyedNetGroupIn,
           uint64_t nLocalHostNonceIn, const CAddress &addrBindIn,
           const std::string &addrNameIn = "", bool fInboundIn = false,
           bool block_relay_only = false);
     ~CNode();
     CNode(const CNode &) = delete;
     CNode &operator=(const CNode &) = delete;
 
 private:
     const NodeId id;
     const uint64_t nLocalHostNonce;
 
     //! Services offered to this peer.
     //!
     //! This is supplied by the parent CConnman during peer connection
     //! (CConnman::ConnectNode()) from its attribute of the same name.
     //!
     //! This is const because there is no protocol defined for renegotiating
     //! services initially offered to a peer. The set of local services we
     //! offer should not change after initialization.
     //!
     //! An interesting example of this is NODE_NETWORK and initial block
     //! download: a node which starts up from scratch doesn't have any blocks
     //! to serve, but still advertises NODE_NETWORK because it will eventually
     //! fulfill this role after IBD completes. P2P code is written in such a
     //! way that it can gracefully handle peers who don't make good on their
     //! service advertisements.
     const ServiceFlags nLocalServices;
 
     const int nMyStartingHeight;
     int nSendVersion{0};
     NetPermissionFlags m_permissionFlags{PF_NONE};
     // Used only by SocketHandler thread
     std::list<CNetMessage> vRecvMsg;
 
     mutable RecursiveMutex cs_addrName;
     std::string addrName GUARDED_BY(cs_addrName);
 
     // Our address, as reported by the peer
     CService addrLocal GUARDED_BY(cs_addrLocal);
     mutable RecursiveMutex cs_addrLocal;
 
 public:
     NodeId GetId() const { return id; }
 
     uint64_t GetLocalNonce() const { return nLocalHostNonce; }
 
     int GetMyStartingHeight() const { return nMyStartingHeight; }
 
     int GetRefCount() const {
         assert(nRefCount >= 0);
         return nRefCount;
     }
 
     bool ReceiveMsgBytes(const Config &config, const char *pch, uint32_t nBytes,
                          bool &complete);
 
     void SetRecvVersion(int nVersionIn) { nRecvVersion = nVersionIn; }
     int GetRecvVersion() const { return nRecvVersion; }
     void SetSendVersion(int nVersionIn);
     int GetSendVersion() const;
 
     CService GetAddrLocal() const;
     //! May not be called more than once
     void SetAddrLocal(const CService &addrLocalIn);
 
     CNode *AddRef() {
         nRefCount++;
         return this;
     }
 
     void Release() { nRefCount--; }
 
     void AddAddressKnown(const CAddress &_addr) {
         assert(m_addr_known);
         m_addr_known->insert(_addr.GetKey());
     }
 
     void PushAddress(const CAddress &_addr, FastRandomContext &insecure_rand) {
         // Known checking here is only to save space from duplicates.
         // SendMessages will filter it again for knowns that were added
         // after addresses were pushed.
         assert(m_addr_known);
         if (_addr.IsValid() && !m_addr_known->contains(_addr.GetKey())) {
             if (vAddrToSend.size() >= MAX_ADDR_TO_SEND) {
                 vAddrToSend[insecure_rand.randrange(vAddrToSend.size())] =
                     _addr;
             } else {
                 vAddrToSend.push_back(_addr);
             }
         }
     }
 
     void AddInventoryKnown(const CInv &inv) {
         if (m_tx_relay != nullptr) {
             LOCK(m_tx_relay->cs_tx_inventory);
             m_tx_relay->filterInventoryKnown.insert(inv.hash);
         }
     }
 
     void PushInventory(const CInv &inv) {
         if (inv.type == MSG_TX && m_tx_relay != nullptr) {
             const TxId txid(inv.hash);
             LOCK(m_tx_relay->cs_tx_inventory);
             if (!m_tx_relay->filterInventoryKnown.contains(txid)) {
                 m_tx_relay->setInventoryTxToSend.insert(txid);
             }
         } else if (inv.type == MSG_BLOCK) {
             const BlockHash hash(inv.hash);
             LOCK(cs_inventory);
             vInventoryBlockToSend.push_back(hash);
         }
     }
 
     void PushBlockHash(const BlockHash &hash) {
         LOCK(cs_inventory);
         vBlockHashesToAnnounce.push_back(hash);
     }
 
     void CloseSocketDisconnect();
 
     void copyStats(CNodeStats &stats, const std::vector<bool> &m_asmap);
 
     ServiceFlags GetLocalServices() const { return nLocalServices; }
 
     std::string GetAddrName() const;
     //! Sets the addrName only if it was not previously set
     void MaybeSetAddrName(const std::string &addrNameIn);
 };
 
 /**
  * Return a timestamp in the future (in microseconds) for exponentially
  * distributed events.
  */
 int64_t PoissonNextSend(int64_t now, int average_interval_seconds);
 
 /** Wrapper to return mockable type */
 inline std::chrono::microseconds
 PoissonNextSend(std::chrono::microseconds now,
                 std::chrono::seconds average_interval) {
     return std::chrono::microseconds{
         PoissonNextSend(now.count(), average_interval.count())};
 }
 
 std::string getSubVersionEB(uint64_t MaxBlockSize);
 std::string userAgent(const Config &config);
 
 #endif // BITCOIN_NET_H