1 files changed, 1100 insertions, 0 deletions

diff --git a/src/net.h b/src/net.h
new file mode 100644
index 0000000..bcd0b2a
--- /dev/null
+++ b/src/net.h
@@ -0,0 +1,1100 @@
+// Copyright (c) 2009 Satoshi Nakamoto
+// Distributed under the MIT/X11 software license, see the accompanying
+// file license.txt or http://www.opensource.org/licenses/mit-license.php.
+
+class CMessageHeader;
+class CAddress;
+class CInv;
+class CRequestTracker;
+class CNode;
+// Defined in main.h, which is included after this file. Only ever used here as
+// a pointer, so the forward declaration is enough.
+class CBlockIndex;
+
+
+
+static const unsigned short DEFAULT_PORT = htons(8433);
+static const unsigned int PUBLISH_HOPS = 5;
+enum
+{
+    NODE_NETWORK = (1 << 0),
+};
+
+
+
+
+
+
+bool GetMyExternalIP(unsigned int& ipRet);
+CNode* ConnectNodeBtf(const string& strBtfAddr);
+CNode* ConnectNodeBtfResolved(const string& strBtfAddr, const string& strMeeting,
+                              const unsigned char enc_pub[32]);
+void ThreadBtfAccept(void* parg);
+void ThreadBtfConnect(void* parg);
+extern string strBtfConnect;
+// Bootstrap seeds added at runtime with /btfseed=ADDRESS:ENCHEX (repeatable).
+// The compiled-in list lives in net.cpp; these are appended to it.
+extern std::vector<std::pair<std::string, std::string> > vBtfExtraSeeds;
+
+// --- .btf peer exchange ---------------------------------------------------
+// Peers gossip signed descriptors so discovery survives a relay outage. Both
+// caps apply to a single "btfpeers" message; the generic header limit is 256 MB,
+// which is no protection at all for something a stranger can send unprompted.
+static const unsigned int MAX_PEX_DESCRIPTORS      = 20;
+static const unsigned int MAX_PEX_DESCRIPTOR_BYTES = 1024;
+// Ignore a peer's exchange more often than this. One announcement per side per
+// connection is the intended traffic; anything faster is someone else's idea.
+static const int64        PEX_MIN_INTERVAL         = 60;
+
+// How long to sit registered at a rendezvous relay before giving up on this
+// attempt and registering again. Bounded because a registration socket that
+// goes quiet is indistinguishable, from inside recv(), from one whose path has
+// died -- and the second kind never wakes up. Five minutes is short enough
+// that a node is unreachable only briefly and long enough that the reconnect
+// traffic is nothing: one per relay per five minutes.
+static const int          BTF_RENDEZVOUS_WAIT_SECS = 300;
+
+// Registrations this node parks at a rendezvous at once.
+//
+// Back to one, and it stays at one until every relay in vBtfMeetingRelays runs
+// the queue from #113. More than one is what keeps a node reachable while one
+// registration is being paired -- but only against a relay that accepts more
+// than one. An older relay closes the previous registration whenever the same
+// node registers again, so several accept threads pointed at one of those
+// evict each other in a loop: thread 2 registers and kills thread 1, thread 3
+// kills thread 2, thread 1 sees its socket die and kills thread 3.
+//
+// #113 called that harmless. It is not. Measured on a node running three
+// threads against the un-upgraded New Jersey relay: 189 registrations in about
+// fifteen minutes -- roughly twelve a minute -- and not one pairing. The node
+// was not merely failing to benefit, it was unreachable through that relay and
+// hammering it. A node with one thread does none of this.
+//
+// The bench that approved #113 could not see it: its harness re-registers by
+// design, which is exactly what hides an eviction loop.
+//
+// Raise this to 3 only when the other two relays are upgraded.
+static const int          BTF_ACCEPT_THREADS       = 1;
+
+// Liveness of an established peer connection. BTF_RENDEZVOUS_WAIT_SECS bounds
+// the wait for a dial to arrive; these bound the connection that comes out of
+// it, which has the same failure mode once it goes quiet.
+//
+// A healthy peer relays a block inventory roughly every nTargetSpacing (two
+// minutes), so silence measured in block intervals is the honest signal.
+// Bitcoin used ninety minutes against ten-minute blocks -- nine intervals --
+// and the same nine intervals here is eighteen minutes; thirty leaves margin
+// for a slow stretch without letting a dead path last an hour.
+static const int          BTF_RECV_TIMEOUT_SECS    = 30 * 60;
+static const int          BTF_SEND_STALL_SECS      = 10 * 60;
+static const int          BTF_HANDSHAKE_GRACE_SECS = 60;
+
+// A serialized object cannot be larger than MAX_SIZE, so no valid network
+// message needs the old 256 MB header allowance. Keep the wire cap aligned with
+// what the deserializer can accept and bound how long one peer may sit on a
+// partial payload after a complete header has arrived.
+static const unsigned int MAX_PROTOCOL_MESSAGE_SIZE = MAX_SIZE;
+static const int          BTF_INCOMPLETE_MESSAGE_TIMEOUT_SECS = 2 * 60;
+
+// Ceiling on simultaneous connections.
+//
+// ThreadSocketHandler watches every peer through one select(), and select()
+// cannot watch more descriptors than FD_SETSIZE. On Windows FD_SET simply
+// stops adding once the set is full -- no error, no log -- so every socket
+// past the limit stays open and is never read again. Nothing capped vNodes,
+// so a node accepted connections it had no way to service, and because new
+// entries go on the end of vNodes it was always the newest connection that
+// starved, including the ones dialed to fix connectivity.
+//
+// Measured on two nodes before this ceiling existed: 277 and 90 CNode objects
+// against 93 and 90 live sockets, and a status bar reporting hundreds of
+// peers for a node that was really talking to thirty.
+//
+// 125 is Bitcoin's number and sits far below FD_SETSIZE on both platforms.
+static const unsigned int MAX_CONNECTIONS = 125;
+
+// A node marked for disconnect is normally held until its buffers drain, so
+// a last message still goes out. But vSend cannot drain through a socket
+// whose far end is gone, and that made such a node immortal: it stayed in
+// vNodes, kept its socket open, and kept being counted. Force it out after
+// this long regardless of what is still buffered.
+static const int64        DISCONNECT_DRAIN_SECS    = 60;
+
+// Send a ping after this long with nothing to say, so a peer running the
+// inactivity check above does not mistake a quiet node for a dead one. Must
+// stay well under BTF_RECV_TIMEOUT_SECS.
+static const int          BTF_PING_INTERVAL_SECS   = 10 * 60;
+
+// How long a node must stay behind the network before it says so, and how
+// often it repeats itself. Five minutes is two and a half block intervals --
+// long enough that ordinary relay lag never trips it.
+static const int          BTF_BEHIND_GRACE_SECS         = 5 * 60;
+static const int          BTF_BEHIND_WARN_INTERVAL_SECS = 5 * 60;
+
+// --- Self-diagnosis -------------------------------------------------------
+//
+// A node that has stopped working looks exactly like a node with nothing to
+// do. That has cost this project real time more than once: a node deaf to
+// most of its peers, a miner allocating one RandomX dataset per thread, a
+// third of arriving blocks missing their parent -- each was found from
+// outside, by reading the process's sockets or its memory from another
+// machine, because the node itself had no way to say so.
+//
+// These counters exist so it can. Cheap to keep, and they name the failures
+// that actually happened rather than the ones that sound impressive.
+extern int   nPeersWatched;        // peers in the last select() set
+extern int64 nBlocksReceived;      // blocks handed to ProcessBlock
+extern int64 nBlocksWithoutParent; // ...of those, how many arrived orphaned
+
+// One report, rendered the same way for the GUI panel and the log, so what a
+// user pastes into an issue is what a developer already knows how to read.
+string GetDiagnosticsText();
+
+#include "sockcount.h"
+
+// Defined in main.cpp. Declared here because CNode announces it in the version
+// message, and net.h is included before main.h.
+extern int nBestHeight;
+
+// Median height announced by the peers we are connected to, or -1 while nobody
+// has told us anything. Median rather than maximum so one peer claiming an
+// absurd height cannot move it.
+int GetPeerMedianHeight();
+
+// Lightweight .btf churn accounting. These counters are diagnostics only: they
+// let an operator tell stale descriptors, relay pairing failures, and paired
+// tunnels that never speak apart before changing behaviour.
+void BtfChurnNoteResolveAttempt();
+void BtfChurnNoteResolveResult(bool fOk);
+void BtfChurnNoteDialAttempt(const string& strBtfAddr, const string& strMeeting);
+void BtfChurnNoteDialResult(const string& strBtfAddr, const string& strMeeting, bool fOk);
+void BtfChurnNoteRegisterResult(const string& strMeeting, bool fOk);
+void BtfChurnNotePairResult(const string& strMeeting, bool fOk);
+void BtfChurnNoteHandshakeTimeout(const string& strBtfAddr, const string& strMeeting,
+                                  bool fRecv, bool fSend);
+
+// Descriptors to hand a peer: ours first, then peers that answered us.
+void BtfPexCollect(std::vector<std::string>& vDescOut);
+// Verify descriptors a peer sent and remember the good ones. Returns how many.
+int  BtfPexAccept(const std::vector<std::string>& vDesc);
+void AbandonRequests(void (*fn)(void*, CDataStream&), void* param1);
+bool AnySubscribed(unsigned int nChannel);
+void ThreadBitcoinMiner(void* parg);
+// Starts MinerThreadCount() miners; returns how many came up.
+int  StartMinerThreads();
+bool StartNode(string& strError=REF(string()));
+bool StopNode();
+void CheckForShutdown(int n);
+
+
+
+
+
+
+
+
+
+//
+// Message header
+//  (4) message start
+//  (12) command
+//  (4) size
+
+// The message start string is designed to be unlikely to occur in normal data.
+// The characters are rarely used upper ascii, not valid as UTF-8, and produce
+// a large 4-byte int at any alignment.
+// Magic bytes unique to the Bitflash network (0xbf = "BF"). Second byte bumped
+// to 0x20 for the 2026 stable relaunch so the old test chain can't interfere.
+static const char pchMessageStart[4] = { 0xbf, 0x20, 0x5c, 0xfd };
+
+class CMessageHeader
+{
+public:
+    enum { COMMAND_SIZE=12 };
+    char pchMessageStart[sizeof(::pchMessageStart)];
+    char pchCommand[COMMAND_SIZE];
+    unsigned int nMessageSize;
+
+    CMessageHeader()
+    {
+        memcpy(pchMessageStart, ::pchMessageStart, sizeof(pchMessageStart));
+        memset(pchCommand, 0, sizeof(pchCommand));
+        pchCommand[1] = 1;
+        nMessageSize = -1;
+    }
+
+    CMessageHeader(const char* pszCommand, unsigned int nMessageSizeIn)
+    {
+        memcpy(pchMessageStart, ::pchMessageStart, sizeof(pchMessageStart));
+        strncpy(pchCommand, pszCommand, COMMAND_SIZE);
+        nMessageSize = nMessageSizeIn;
+    }
+
+    IMPLEMENT_SERIALIZE
+    (
+        READWRITE(FLATDATA(pchMessageStart));
+        READWRITE(FLATDATA(pchCommand));
+        READWRITE(nMessageSize);
+    )
+
+    string GetCommand()
+    {
+        if (pchCommand[COMMAND_SIZE-1] == 0)
+            return string(pchCommand, pchCommand + strlen(pchCommand));
+        else
+            return string(pchCommand, pchCommand + COMMAND_SIZE);
+    }
+
+    bool IsValid()
+    {
+        // Check start string
+        if (memcmp(pchMessageStart, ::pchMessageStart, sizeof(pchMessageStart)) != 0)
+            return false;
+
+        // Check the command string for errors
+        for (char* p1 = pchCommand; p1 < pchCommand + COMMAND_SIZE; p1++)
+        {
+            if (*p1 == 0)
+            {
+                // Must be all zeros after the first zero
+                for (; p1 < pchCommand + COMMAND_SIZE; p1++)
+                    if (*p1 != 0)
+                        return false;
+            }
+            else if (*p1 < ' ' || *p1 > 0x7E)
+                return false;
+        }
+
+        // Message size
+        if (nMessageSize > MAX_PROTOCOL_MESSAGE_SIZE)
+        {
+            if (LogAcceptsCategory("net")) printf("CMessageHeader::IsValid() : nMessageSize too large %u\n", nMessageSize);
+            return false;
+        }
+
+        return true;
+    }
+};
+
+
+
+
+
+
+static const unsigned char pchIPv4[12] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff };
+
+class CAddress
+{
+public:
+    uint64 nServices;
+    unsigned char pchReserved[12];
+    unsigned int ip;
+    unsigned short port;
+
+    // disk only
+    unsigned int nTime;
+
+    // memory only
+    unsigned int nLastFailed;
+
+    CAddress()
+    {
+        nServices = 0;
+        memcpy(pchReserved, pchIPv4, sizeof(pchReserved));
+        ip = 0;
+        port = DEFAULT_PORT;
+        nTime = GetAdjustedTime();
+        nLastFailed = 0;
+    }
+
+    CAddress(unsigned int ipIn, unsigned short portIn, uint64 nServicesIn=0)
+    {
+        nServices = nServicesIn;
+        memcpy(pchReserved, pchIPv4, sizeof(pchReserved));
+        ip = ipIn;
+        port = portIn;
+        nTime = GetAdjustedTime();
+        nLastFailed = 0;
+    }
+
+    explicit CAddress(const struct sockaddr_in& sockaddr, uint64 nServicesIn=0)
+    {
+        nServices = nServicesIn;
+        memcpy(pchReserved, pchIPv4, sizeof(pchReserved));
+        ip = sockaddr.sin_addr.s_addr;
+        port = sockaddr.sin_port;
+        nTime = GetAdjustedTime();
+        nLastFailed = 0;
+    }
+
+    explicit CAddress(const char* pszIn, uint64 nServicesIn=0)
+    {
+        nServices = nServicesIn;
+        memcpy(pchReserved, pchIPv4, sizeof(pchReserved));
+        ip = 0;
+        port = DEFAULT_PORT;
+        nTime = GetAdjustedTime();
+        nLastFailed = 0;
+
+        char psz[100];
+        if (strlen(pszIn) > ARRAYLEN(psz)-1)
+            return;
+        strcpy(psz, pszIn);
+        unsigned int a, b, c, d, e;
+        if (sscanf(psz, "%u.%u.%u.%u:%u", &a, &b, &c, &d, &e) < 4)
+            return;
+        char* pszPort = strchr(psz, ':');
+        if (pszPort)
+        {
+            *pszPort++ = '\0';
+            port = htons(atoi(pszPort));
+        }
+        ip = inet_addr(psz);
+    }
+
+    IMPLEMENT_SERIALIZE
+    (
+        if (nType & SER_DISK)
+        {
+            READWRITE(nVersion);
+            READWRITE(nTime);
+        }
+        READWRITE(nServices);
+        READWRITE(FLATDATA(pchReserved));
+        READWRITE(ip);
+        READWRITE(port);
+    )
+
+    friend inline bool operator==(const CAddress& a, const CAddress& b)
+    {
+        return (memcmp(a.pchReserved, b.pchReserved, sizeof(a.pchReserved)) == 0 &&
+                a.ip   == b.ip &&
+                a.port == b.port);
+    }
+
+    friend inline bool operator<(const CAddress& a, const CAddress& b)
+    {
+        int ret = memcmp(a.pchReserved, b.pchReserved, sizeof(a.pchReserved));
+        if (ret < 0)
+            return true;
+        else if (ret == 0)
+        {
+            if (ntohl(a.ip) < ntohl(b.ip))
+                return true;
+            else if (a.ip == b.ip)
+                return ntohs(a.port) < ntohs(b.port);
+        }
+        return false;
+    }
+
+    vector<unsigned char> GetKey() const
+    {
+        CDataStream ss;
+        ss.reserve(18);
+        ss << FLATDATA(pchReserved) << ip << port;
+
+        #if defined(_MSC_VER) && _MSC_VER < 1300
+        return vector<unsigned char>((unsigned char*)&ss.begin()[0], (unsigned char*)&ss.end()[0]);
+        #else
+        return vector<unsigned char>(ss.begin(), ss.end());
+        #endif
+    }
+
+    struct sockaddr_in GetSockAddr() const
+    {
+        struct sockaddr_in sockaddr;
+        sockaddr.sin_family = AF_INET;
+        sockaddr.sin_addr.s_addr = ip;
+        sockaddr.sin_port = port;
+        return sockaddr;
+    }
+
+    bool IsIPv4() const
+    {
+        return (memcmp(pchReserved, pchIPv4, sizeof(pchIPv4)) == 0);
+    }
+
+    bool IsRoutable() const
+    {
+        return !(GetByte(3) == 10 || (GetByte(3) == 192 && GetByte(2) == 168));
+    }
+
+    unsigned char GetByte(int n) const
+    {
+        return ((unsigned char*)&ip)[3-n];
+    }
+
+    string ToStringIPPort() const
+    {
+        return strprintf("%u.%u.%u.%u:%u", GetByte(3), GetByte(2), GetByte(1), GetByte(0), ntohs(port));
+    }
+
+    string ToStringIP() const
+    {
+        return strprintf("%u.%u.%u.%u", GetByte(3), GetByte(2), GetByte(1), GetByte(0));
+    }
+
+    string ToString() const
+    {
+        return strprintf("%u.%u.%u.%u:%u", GetByte(3), GetByte(2), GetByte(1), GetByte(0), ntohs(port));
+        //return strprintf("%u.%u.%u.%u", GetByte(3), GetByte(2), GetByte(1), GetByte(0));
+    }
+
+    void print() const
+    {
+        if (LogAcceptsCategory("net")) printf("CAddress(%s)\n", ToString().c_str());
+    }
+};
+
+
+
+
+
+
+
+enum
+{
+    MSG_TX = 1,
+    MSG_BLOCK,
+    MSG_REVIEW,
+    MSG_PRODUCT,
+    MSG_TABLE,
+};
+
+static const char* ppszTypeName[] =
+{
+    "ERROR",
+    "tx",
+    "block",
+    "review",
+    "product",
+    "table",
+};
+
+class CInv
+{
+public:
+    int type;
+    uint256 hash;
+
+    CInv()
+    {
+        type = 0;
+        hash = 0;
+    }
+
+    CInv(int typeIn, const uint256& hashIn)
+    {
+        type = typeIn;
+        hash = hashIn;
+    }
+
+    CInv(const string& strType, const uint256& hashIn)
+    {
+        int i;
+        for (i = 1; i < ARRAYLEN(ppszTypeName); i++)
+        {
+            if (strType == ppszTypeName[i])
+            {
+                type = i;
+                break;
+            }
+        }
+        if (i == ARRAYLEN(ppszTypeName))
+            throw std::out_of_range(strprintf("CInv::CInv(string, uint256) : unknown type '%s'", strType.c_str()));
+        hash = hashIn;
+    }
+
+    IMPLEMENT_SERIALIZE
+    (
+        READWRITE(type);
+        READWRITE(hash);
+    )
+
+    friend inline bool operator<(const CInv& a, const CInv& b)
+    {
+        return (a.type < b.type || (a.type == b.type && a.hash < b.hash));
+    }
+
+    bool IsKnownType() const
+    {
+        return (type >= 1 && type < ARRAYLEN(ppszTypeName));
+    }
+
+    const char* GetCommand() const
+    {
+        if (!IsKnownType())
+            // Was "type=% unknown type": the % swallowed the space as a flag and
+            // the u as the conversion, so this read "type= 3nknown type".
+            throw std::out_of_range(strprintf("CInv::GetCommand() : type=%d unknown type", type));
+        return ppszTypeName[type];
+    }
+
+    string ToString() const
+    {
+        return strprintf("%s %s", GetCommand(), hash.ToString().substr(0,14).c_str());
+    }
+
+    void print() const
+    {
+        if (LogAcceptsCategory("net")) printf("CInv(%s)\n", ToString().c_str());
+    }
+};
+
+
+
+
+
+class CRequestTracker
+{
+public:
+    void (*fn)(void*, CDataStream&);
+    void* param1;
+
+    explicit CRequestTracker(void (*fnIn)(void*, CDataStream&)=NULL, void* param1In=NULL)
+    {
+        fn = fnIn;
+        param1 = param1In;
+    }
+
+    bool IsNull()
+    {
+        return fn == NULL;
+    }
+};
+
+
+
+
+
+extern bool fClient;
+extern uint64 nLocalServices;
+extern CAddress addrLocalHost;
+extern unsigned short nListenPort;
+extern CNode* pnodeLocalHost;
+extern bool fShutdown;
+extern array<bool, 10> vfThreadRunning;
+extern vector<CNode*> vNodes;
+extern CCriticalSection cs_vNodes;
+extern map<CInv, CDataStream> mapRelay;
+extern deque<pair<int64, CInv> > vRelayExpiration;
+extern CCriticalSection cs_mapRelay;
+extern map<CInv, int64> mapAlreadyAskedFor;
+
+
+
+
+
+class CNode
+{
+public:
+    // socket
+    uint64 nServices;
+    SOCKET hSocket;
+    CDataStream vSend;
+    CDataStream vRecv;
+    CCriticalSection cs_vSend;
+    CCriticalSection cs_vRecv;
+    unsigned int nPushPos;
+    CAddress addr;
+    int nVersion;
+    bool fClient;
+    bool fInbound;
+    bool fNetworkNode;
+    bool fDisconnect;
+protected:
+    int nRefCount;
+public:
+    int64 nReleaseTime;
+    int64 nDisconnectSince;
+    map<uint256, CRequestTracker> mapRequests;
+    CCriticalSection cs_mapRequests;
+
+    // inventory based relay
+    set<CInv> setInventoryKnown;
+    set<CInv> setInventoryKnown2;
+    vector<CInv> vInventoryToSend;
+    CCriticalSection cs_inventory;
+    multimap<int64, CInv> mapAskFor;
+
+    // publish and subscription
+    vector<char> vfSubscribe;
+
+    // Last "btfpeers" we accepted from this node, to rate-limit the exchange.
+    int64 nLastPexRecv;
+
+    // Last getblocks we sent this peer, so we do not ask the same question
+    // over and over. See CNode::PushGetBlocks.
+    CBlockIndex* pindexLastGetBlocksBegin;
+    uint256      hashLastGetBlocksEnd;
+
+    // Liveness. A peer whose network path dies silently -- NAT drops an idle
+    // mapping, a relay restarts, a route changes -- never sends FIN, so the
+    // socket stays readable-never and the node simply stops hearing from it
+    // with no error anywhere. These stamps are the only way to tell that
+    // apart from a peer that merely has nothing to say.
+    int64 nTimeConnected;
+    int64 nLastSend;
+    int64 nLastRecv;
+    int64 nLastSendEmpty;
+    int64 nIncompleteMessageStart;
+    unsigned int nIncompleteMessageSize;
+    string strIncompleteMessageCommand;
+    string strBtfAddr;
+    string strBtfMeeting;
+
+    // Height this peer announced in its version message, or -1 if it sent a
+    // version message that predates the field. Knowing how far along everyone
+    // else is, is the only way a node can tell "in sync" from "not hearing".
+    int nStartingHeight;
+
+
+    CNode(SOCKET hSocketIn, CAddress addrIn, bool fInboundIn=false)
+    {
+        nServices = 0;
+        hSocket = hSocketIn;
+        vSend.SetType(SER_NETWORK);
+        vRecv.SetType(SER_NETWORK);
+        nPushPos = -1;
+        addr = addrIn;
+        nVersion = 0;
+        fClient = false; // set by version message
+        fInbound = fInboundIn;
+        fNetworkNode = false;
+        fDisconnect = false;
+        nRefCount = 0;
+        nReleaseTime = 0;
+        nDisconnectSince = 0;
+        nLastPexRecv = 0;
+        pindexLastGetBlocksBegin = NULL;
+        hashLastGetBlocksEnd = 0;
+        nTimeConnected = GetTime();
+        nLastSend = 0;
+        nLastRecv = 0;
+        nLastSendEmpty = GetTime();
+        nIncompleteMessageStart = 0;
+        nIncompleteMessageSize = 0;
+        strIncompleteMessageCommand.clear();
+        strBtfAddr.clear();
+        strBtfMeeting.clear();
+        nStartingHeight = -1;
+        vfSubscribe.assign(256, false);
+
+        // Push a version message
+        /// when NTP implemented, change to just nTime = GetAdjustedTime()
+        int64 nTime = (fInbound ? GetAdjustedTime() : GetTime());
+        // nBestHeight goes last so a node that predates it stops reading after
+        // addr and treats the rest as trailing bytes, which cost it a log line
+        // and nothing else.
+        PushMessage("version", VERSION, nLocalServices, nTime, addr, nBestHeight);
+    }
+
+    // Disconnect() closes the socket and sets this to INVALID_SOCKET, so by the
+    // time a node is deleted there is normally nothing left to do here. It used
+    // not to: Disconnect() closed the handle and left the number in place, and
+    // this destructor closed that same number a second time -- with a raw
+    // closesocket() that the socket accounting never saw, so neither the double
+    // close nor the stale claim showed up in any report.
+    //
+    // A double close is not a harmless no-op. Between the two, the operating
+    // system is free to hand that number to a new socket -- this node opens
+    // hundreds a minute -- and the second close then takes down a connection
+    // that belongs to somebody else, which the log can only report as a peer
+    // vanishing for no reason. `dropping node: its socket is no longer valid`
+    // is what that looks like from the outside.
+    ~CNode()
+    {
+        if (hSocket != INVALID_SOCKET)
+        {
+            BtfCloseSocket(hSocket);
+            hSocket = INVALID_SOCKET;
+        }
+    }
+
+private:
+    CNode(const CNode&);
+    void operator=(const CNode&);
+public:
+
+
+    bool ReadyToDisconnect()
+    {
+        return fDisconnect || GetRefCount() <= 0;
+    }
+
+    int GetRefCount()
+    {
+        return max(nRefCount, 0) + (GetTime() < nReleaseTime ? 1 : 0);
+    }
+
+    void AddRef(int64 nTimeout=0)
+    {
+        if (nTimeout != 0)
+            nReleaseTime = max(nReleaseTime, GetTime() + nTimeout);
+        else
+            nRefCount++;
+    }
+
+    void Release()
+    {
+        nRefCount--;
+    }
+
+
+
+    void AddInventoryKnown(const CInv& inv)
+    {
+        CRITICAL_BLOCK(cs_inventory)
+            setInventoryKnown.insert(inv);
+    }
+
+    void PushInventory(const CInv& inv)
+    {
+        CRITICAL_BLOCK(cs_inventory)
+            if (!setInventoryKnown.count(inv))
+                vInventoryToSend.push_back(inv);
+    }
+
+    void AskFor(const CInv& inv)
+    {
+        // We're using mapAskFor as a priority queue,
+        // the key is the earliest time the request can be sent
+        int64& nRequestTime = mapAlreadyAskedFor[inv];
+        if (LogAcceptsCategory("net")) printf("askfor %s  %lld\n", inv.ToString().c_str(), nRequestTime);
+
+        // Make sure not to reuse time indexes to keep things in the same order
+        int64 nNow = (GetTime() - 1) * 1000000;
+        static int64 nLastTime;
+        nLastTime = nNow = max(nNow, ++nLastTime);
+
+        // Each retry is 2 minutes after the last
+        nRequestTime = max(nRequestTime + 2 * 60 * 1000000, nNow);
+        mapAskFor.insert(make_pair(nRequestTime, inv));
+    }
+
+
+
+    void BeginMessage(const char* pszCommand)
+    {
+        EnterCriticalSection(&cs_vSend);
+        if (nPushPos != -1)
+            AbortMessage();
+        nPushPos = vSend.size();
+        vSend << CMessageHeader(pszCommand, 0);
+        if (LogAcceptsCategory("net")) printf("sending: %-12s ", pszCommand);
+    }
+
+    void AbortMessage()
+    {
+        if (nPushPos == -1)
+            return;
+        vSend.resize(nPushPos);
+        nPushPos = -1;
+        LeaveCriticalSection(&cs_vSend);
+        if (LogAcceptsCategory("net")) printf("(aborted)\n");
+    }
+
+    void EndMessage()
+    {
+        extern int nDropMessagesTest;
+        if (nDropMessagesTest > 0 && GetRand(nDropMessagesTest) == 0)
+        {
+            if (LogAcceptsCategory("net")) printf("dropmessages DROPPING SEND MESSAGE\n");
+            AbortMessage();
+            return;
+        }
+
+        if (nPushPos == -1)
+            return;
+
+        // Patch in the size
+        unsigned int nSize = vSend.size() - nPushPos - sizeof(CMessageHeader);
+        memcpy((char*)&vSend[nPushPos] + offsetof(CMessageHeader, nMessageSize), &nSize, sizeof(nSize));
+
+        if (LogAcceptsCategory("net")) printf("(%d bytes)  ", nSize);
+        //for (int i = nPushPos+sizeof(CMessageHeader); i < min(vSend.size(), nPushPos+sizeof(CMessageHeader)+20U); i++)
+        //    printf("%02x ", vSend[i] & 0xff);
+        if (LogAcceptsCategory("net")) printf("\n");
+
+        nPushPos = -1;
+        LeaveCriticalSection(&cs_vSend);
+    }
+
+    void EndMessageAbortIfEmpty()
+    {
+        if (nPushPos == -1)
+            return;
+        int nSize = vSend.size() - nPushPos - sizeof(CMessageHeader);
+        if (nSize > 0)
+            EndMessage();
+        else
+            AbortMessage();
+    }
+
+    const char* GetMessageCommand() const
+    {
+        if (nPushPos == -1)
+            return "";
+        return &vSend[nPushPos] + offsetof(CMessageHeader, pchCommand);
+    }
+
+
+
+
+    // Ask this peer to fill in blocks we are missing, but only once per
+    // question.
+    //
+    // Every orphan block fires one of these, and an inv for a block we already
+    // hold as an orphan fires another. A node that is missing part of the
+    // chain therefore asks the same peer the same thing repeatedly: measured
+    // on a production node, 1287 orphan blocks out of 4117 processed, and 97
+    // "already have block" from the answers coming back more than once. The
+    // duplicate answers create more orphans, which fire more requests.
+    //
+    // Remembering the last question asked breaks that loop. Same fix Bitcoin
+    // made in e2c2648c1.
+    // Body lives in net.cpp: it builds a CBlockLocator, which main.h defines,
+    // and main.h is included after this file.
+    void PushGetBlocks(CBlockIndex* pindexBegin, uint256 hashEnd);
+
+    void PushMessage(const char* pszCommand)
+    {
+        try
+        {
+            BeginMessage(pszCommand);
+            EndMessage();
+        }
+        catch (...)
+        {
+            AbortMessage();
+            throw;
+        }
+    }
+
+    template<typename T1>
+    void PushMessage(const char* pszCommand, const T1& a1)
+    {
+        try
+        {
+            BeginMessage(pszCommand);
+            vSend << a1;
+            EndMessage();
+        }
+        catch (...)
+        {
+            AbortMessage();
+            throw;
+        }
+    }
+
+    template<typename T1, typename T2>
+    void PushMessage(const char* pszCommand, const T1& a1, const T2& a2)
+    {
+        try
+        {
+            BeginMessage(pszCommand);
+            vSend << a1 << a2;
+            EndMessage();
+        }
+        catch (...)
+        {
+            AbortMessage();
+            throw;
+        }
+    }
+
+    template<typename T1, typename T2, typename T3>
+    void PushMessage(const char* pszCommand, const T1& a1, const T2& a2, const T3& a3)
+    {
+        try
+        {
+            BeginMessage(pszCommand);
+            vSend << a1 << a2 << a3;
+            EndMessage();
+        }
+        catch (...)
+        {
+            AbortMessage();
+            throw;
+        }
+    }
+
+    template<typename T1, typename T2, typename T3, typename T4>
+    void PushMessage(const char* pszCommand, const T1& a1, const T2& a2, const T3& a3, const T4& a4)
+    {
+        try
+        {
+            BeginMessage(pszCommand);
+            vSend << a1 << a2 << a3 << a4;
+            EndMessage();
+        }
+        catch (...)
+        {
+            AbortMessage();
+            throw;
+        }
+    }
+
+    template<typename T1, typename T2, typename T3, typename T4, typename T5>
+    void PushMessage(const char* pszCommand, const T1& a1, const T2& a2, const T3& a3, const T4& a4, const T5& a5)
+    {
+        try
+        {
+            BeginMessage(pszCommand);
+            vSend << a1 << a2 << a3 << a4 << a5;
+            EndMessage();
+        }
+        catch (...)
+        {
+            AbortMessage();
+            throw;
+        }
+    }
+
+
+    void PushRequest(const char* pszCommand,
+                     void (*fn)(void*, CDataStream&), void* param1)
+    {
+        uint256 hashReply;
+        RAND_bytes((unsigned char*)&hashReply, sizeof(hashReply));
+
+        CRITICAL_BLOCK(cs_mapRequests)
+            mapRequests[hashReply] = CRequestTracker(fn, param1);
+
+        PushMessage(pszCommand, hashReply);
+    }
+
+    template<typename T1>
+    void PushRequest(const char* pszCommand, const T1& a1,
+                     void (*fn)(void*, CDataStream&), void* param1)
+    {
+        uint256 hashReply;
+        RAND_bytes((unsigned char*)&hashReply, sizeof(hashReply));
+
+        CRITICAL_BLOCK(cs_mapRequests)
+            mapRequests[hashReply] = CRequestTracker(fn, param1);
+
+        PushMessage(pszCommand, hashReply, a1);
+    }
+
+    template<typename T1, typename T2>
+    void PushRequest(const char* pszCommand, const T1& a1, const T2& a2,
+                     void (*fn)(void*, CDataStream&), void* param1)
+    {
+        uint256 hashReply;
+        RAND_bytes((unsigned char*)&hashReply, sizeof(hashReply));
+
+        CRITICAL_BLOCK(cs_mapRequests)
+            mapRequests[hashReply] = CRequestTracker(fn, param1);
+
+        PushMessage(pszCommand, hashReply, a1, a2);
+    }
+
+
+
+    bool IsSubscribed(unsigned int nChannel);
+    void Subscribe(unsigned int nChannel, unsigned int nHops=0);
+    void CancelSubscribe(unsigned int nChannel);
+    void Disconnect();
+};
+
+
+
+
+
+
+
+
+
+
+inline void RelayInventory(const CInv& inv)
+{
+    // Put on lists to offer to the other nodes
+    CRITICAL_BLOCK(cs_vNodes)
+        foreach(CNode* pnode, vNodes)
+            pnode->PushInventory(inv);
+}
+
+template<typename T>
+void RelayMessage(const CInv& inv, const T& a)
+{
+    CDataStream ss(SER_NETWORK);
+    ss.reserve(10000);
+    ss << a;
+    RelayMessage(inv, ss);
+}
+
+template<>
+inline void RelayMessage<>(const CInv& inv, const CDataStream& ss)
+{
+    CRITICAL_BLOCK(cs_mapRelay)
+    {
+        // Expire old relay messages
+        while (!vRelayExpiration.empty() && vRelayExpiration.front().first < GetTime())
+        {
+            mapRelay.erase(vRelayExpiration.front().second);
+            vRelayExpiration.pop_front();
+        }
+
+        // Save original serialized message so newer versions are preserved
+        mapRelay[inv] = ss;
+        vRelayExpiration.push_back(make_pair(GetTime() + 15 * 60, inv));
+    }
+
+    RelayInventory(inv);
+}
+
+
+
+
+
+
+
+
+//
+// Templates for the publish and subscription system.
+// The object being published as T& obj needs to have:
+//   a set<unsigned int> setSources member
+//   specializations of AdvertInsert and AdvertErase
+// Currently implemented for CTable and CProduct.
+//
+
+template<typename T>
+void AdvertStartPublish(CNode* pfrom, unsigned int nChannel, unsigned int nHops, T& obj)
+{
+    // Add to sources
+    obj.setSources.insert(pfrom->addr.ip);
+
+    if (!AdvertInsert(obj))
+        return;
+
+    // Relay
+    CRITICAL_BLOCK(cs_vNodes)
+        foreach(CNode* pnode, vNodes)
+            if (pnode != pfrom && (nHops < PUBLISH_HOPS || pnode->IsSubscribed(nChannel)))
+                pnode->PushMessage("publish", nChannel, nHops, obj);
+}
+
+template<typename T>
+void AdvertStopPublish(CNode* pfrom, unsigned int nChannel, unsigned int nHops, T& obj)
+{
+    uint256 hash = obj.GetHash();
+
+    CRITICAL_BLOCK(cs_vNodes)
+        foreach(CNode* pnode, vNodes)
+            if (pnode != pfrom && (nHops < PUBLISH_HOPS || pnode->IsSubscribed(nChannel)))
+                pnode->PushMessage("pub-cancel", nChannel, nHops, hash);
+
+    AdvertErase(obj);
+}
+
+template<typename T>
+void AdvertRemoveSource(CNode* pfrom, unsigned int nChannel, unsigned int nHops, T& obj)
+{
+    // Remove a source
+    obj.setSources.erase(pfrom->addr.ip);
+
+    // If no longer supported by any sources, cancel it
+    if (obj.setSources.empty())
+        AdvertStopPublish(pfrom, nChannel, nHops, obj);
+}