net.h

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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2021 The Bitcoin Core 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 <chainparams.h>
#include <common/bloom.h>
#include <compat.h>
#include <consensus/amount.h>
#include <crypto/siphash.h>
#include <hash.h>
#include <i2p.h>
#include <net_permissions.h>
#include <netaddress.h>
#include <netbase.h>
#include <policy/feerate.h>
#include <protocol.h>
#include <random.h>
#include <span.h>
#include <streams.h>
#include <sync.h>
#include <threadinterrupt.h>
#include <uint256.h>
#include <util/check.h>
#include <util/sock.h>
 
#include <atomic>
#include <condition_variable>
#include <cstdint>
#include <deque>
#include <map>
#include <memory>
#include <optional>
#include <thread>
#include <vector>
 
class AddrMan;
class BanMan;
class CNode;
class CScheduler;
struct bilingual_str;
 
static const bool DEFAULT_WHITELISTRELAY = true;
static const bool DEFAULT_WHITELISTFORCERELAY = false;
 
static constexpr std::chrono::minutes TIMEOUT_INTERVAL{20};
static constexpr auto FEELER_INTERVAL = 2min;
static constexpr auto EXTRA_BLOCK_RELAY_ONLY_PEER_INTERVAL = 5min;
static const unsigned int MAX_PROTOCOL_MESSAGE_LENGTH = 4 * 1000 * 1000;
static const unsigned int MAX_SUBVERSION_LENGTH = 256;
static const int MAX_OUTBOUND_FULL_RELAY_CONNECTIONS = 8;
static const int MAX_ADDNODE_CONNECTIONS = 8;
static const int MAX_BLOCK_RELAY_ONLY_CONNECTIONS = 2;
static const int MAX_FEELER_CONNECTIONS = 1;
static const bool DEFAULT_LISTEN = true;
static const unsigned int DEFAULT_MAX_PEER_CONNECTIONS = 125;
static const std::string DEFAULT_MAX_UPLOAD_TARGET{"0M"};
static const bool DEFAULT_BLOCKSONLY = false;
static const int64_t DEFAULT_PEER_CONNECT_TIMEOUT = 60;
static const int NUM_FDS_MESSAGE_CAPTURE = 1;
 
static constexpr bool DEFAULT_FORCEDNSSEED{false};
static constexpr bool DEFAULT_DNSSEED{true};
static constexpr bool DEFAULT_FIXEDSEEDS{true};
static const size_t DEFAULT_MAXRECEIVEBUFFER = 5 * 1000;
static const size_t DEFAULT_MAXSENDBUFFER    = 1 * 1000;
 
typedef int64_t NodeId;
 
struct AddedNodeInfo
{
    std::string strAddedNode;
    CService resolvedAddress;
    bool fConnected;
    bool fInbound;
};
 
class 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<unsigned char> data;
    std::string m_type;
};
 
enum class ConnectionType {
    INBOUND,
 
    OUTBOUND_FULL_RELAY,
 
 
    MANUAL,
 
    FEELER,
 
    BLOCK_RELAY,
 
    ADDR_FETCH,
};
 
std::string ConnectionTypeAsString(ConnectionType conn_type);
void Discover();
uint16_t GetListenPort();
 
enum
{
    LOCAL_NONE,   // unknown
    LOCAL_IF,     // address a local interface listens on
    LOCAL_BIND,   // address explicit bound to
    LOCAL_MAPPED, // address reported by UPnP or NAT-PMP
    LOCAL_MANUAL, // address explicitly specified (-externalip=)
 
    LOCAL_MAX
};
 
bool IsPeerAddrLocalGood(CNode *pnode);
std::optional<CAddress> GetLocalAddrForPeer(CNode *pnode);
 
void SetReachable(enum Network net, bool reachable);
bool IsReachable(enum Network net);
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 std::string strSubVersion;
 
struct LocalServiceInfo {
    int nScore;
    uint16_t nPort;
};
 
extern Mutex g_maplocalhost_mutex;
extern std::map<CNetAddr, LocalServiceInfo> mapLocalHost GUARDED_BY(g_maplocalhost_mutex);
 
extern const std::string NET_MESSAGE_COMMAND_OTHER;
typedef std::map<std::string, uint64_t> mapMsgCmdSize; //command, total bytes
 
class CNodeStats
{
public:
    NodeId nodeid;
    ServiceFlags nServices;
    bool fRelayTxes;
    std::chrono::seconds m_last_send;
    std::chrono::seconds m_last_recv;
    std::chrono::seconds m_last_tx_time;
    std::chrono::seconds m_last_block_time;
    std::chrono::seconds m_connected;
    int64_t nTimeOffset;
    std::string m_addr_name;
    int nVersion;
    std::string cleanSubVer;
    bool fInbound;
    bool m_bip152_highbandwidth_to;
    bool m_bip152_highbandwidth_from;
    int m_starting_height;
    uint64_t nSendBytes;
    mapMsgCmdSize mapSendBytesPerMsgCmd;
    uint64_t nRecvBytes;
    mapMsgCmdSize mapRecvBytesPerMsgCmd;
    NetPermissionFlags m_permissionFlags;
    std::chrono::microseconds m_last_ping_time;
    std::chrono::microseconds m_min_ping_time;
    CAmount 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;
    // Network the peer connected through
    Network m_network;
    uint32_t m_mapped_as;
    ConnectionType m_conn_type;
};
 
 
class CNetMessage {
public:
    CDataStream m_recv;                  
    std::chrono::microseconds m_time{0}; 
    uint32_t m_message_size{0};          
    uint32_t m_raw_message_size{0};      
    std::string m_type;
 
    CNetMessage(CDataStream&& recv_in) : m_recv(std::move(recv_in)) {}
 
    void SetVersion(int nVersionIn)
    {
        m_recv.SetVersion(nVersionIn);
    }
};
 
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;
    virtual int Read(Span<const uint8_t>& msg_bytes) = 0;
    // decomposes a message from the context
    virtual CNetMessage GetMessage(std::chrono::microseconds time, bool& reject_message) = 0;
    virtual ~TransportDeserializer() {}
};
 
class V1TransportDeserializer final : public TransportDeserializer
{
private:
    const CChainParams& m_chain_params;
    const NodeId m_node_id; // Only for logging
    mutable CHash256 hasher;
    mutable uint256 data_hash;
    bool in_data;                   // parsing header (false) or data (true)
    CDataStream hdrbuf;             // partially received header
    CMessageHeader hdr;             // complete header
    CDataStream vRecv;              // received message data
    unsigned int nHdrPos;
    unsigned int nDataPos;
 
    const uint256& GetMessageHash() const;
    int readHeader(Span<const uint8_t> msg_bytes);
    int readData(Span<const uint8_t> msg_bytes);
 
    void Reset() {
        vRecv.clear();
        hdrbuf.clear();
        hdrbuf.resize(24);
        in_data = false;
        nHdrPos = 0;
        nDataPos = 0;
        data_hash.SetNull();
        hasher.Reset();
    }
 
public:
    V1TransportDeserializer(const CChainParams& chain_params, const NodeId node_id, int nTypeIn, int nVersionIn)
        : m_chain_params(chain_params),
          m_node_id(node_id),
          hdrbuf(nTypeIn, nVersionIn),
          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(Span<const uint8_t>& msg_bytes) override
    {
        int ret = in_data ? readData(msg_bytes) : readHeader(msg_bytes);
        if (ret < 0) {
            Reset();
        } else {
            msg_bytes = msg_bytes.subspan(ret);
        }
        return ret;
    }
    CNetMessage GetMessage(std::chrono::microseconds time, bool& reject_message) override;
};
 
class TransportSerializer {
public:
    // prepare message for transport (header construction, error-correction computation, payload encryption, etc.)
    virtual void prepareForTransport(CSerializedNetMsg& msg, std::vector<unsigned char>& header) = 0;
    virtual ~TransportSerializer() {}
};
 
class V1TransportSerializer  : public TransportSerializer {
public:
    void prepareForTransport(CSerializedNetMsg& msg, std::vector<unsigned char>& header) override;
};
 
class CNode
{
    friend class CConnman;
    friend struct ConnmanTestMsg;
 
public:
    std::unique_ptr<TransportDeserializer> m_deserializer;
    std::unique_ptr<TransportSerializer> m_serializer;
 
    NetPermissionFlags m_permissionFlags{NetPermissionFlags::None};
    std::atomic<ServiceFlags> nServices{NODE_NONE};
    SOCKET hSocket GUARDED_BY(cs_hSocket);
    size_t nSendSize GUARDED_BY(cs_vSend){0};
    size_t nSendOffset GUARDED_BY(cs_vSend){0};
    uint64_t nSendBytes GUARDED_BY(cs_vSend){0};
    std::deque<std::vector<unsigned char>> vSendMsg GUARDED_BY(cs_vSend);
    Mutex cs_vSend;
    Mutex cs_hSocket;
    Mutex cs_vRecv;
 
    RecursiveMutex cs_vProcessMsg;
    std::list<CNetMessage> vProcessMsg GUARDED_BY(cs_vProcessMsg);
    size_t nProcessQueueSize{0};
 
    RecursiveMutex cs_sendProcessing;
 
    uint64_t nRecvBytes GUARDED_BY(cs_vRecv){0};
 
    std::atomic<std::chrono::seconds> m_last_send{0s};
    std::atomic<std::chrono::seconds> m_last_recv{0s};
    const std::chrono::seconds m_connected;
    std::atomic<int64_t> nTimeOffset{0};
    // Address of this peer
    const CAddress addr;
    // Bind address of our side of the connection
    const CAddress addrBind;
    const std::string m_addr_name;
    const bool m_inbound_onion;
    std::atomic<int> nVersion{0};
    Mutex m_subver_mutex;
    std::string cleanSubVer GUARDED_BY(m_subver_mutex){};
    bool m_prefer_evict{false}; // This peer is preferred for eviction.
    bool HasPermission(NetPermissionFlags permission) const {
        return NetPermissions::HasFlag(m_permissionFlags, permission);
    }
    bool fClient{false}; // set by version message
    bool m_limited_node{false}; //after BIP159, set by version message
    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};
    CSemaphoreGrant grantOutbound;
    std::atomic<int> nRefCount{0};
 
    const uint64_t nKeyedNetGroup;
    std::atomic_bool fPauseRecv{false};
    std::atomic_bool fPauseSend{false};
 
    bool IsOutboundOrBlockRelayConn() const {
        switch (m_conn_type) {
            case ConnectionType::OUTBOUND_FULL_RELAY:
            case ConnectionType::BLOCK_RELAY:
                return true;
            case ConnectionType::INBOUND:
            case ConnectionType::MANUAL:
            case ConnectionType::ADDR_FETCH:
            case ConnectionType::FEELER:
                return false;
        } // no default case, so the compiler can warn about missing cases
 
        assert(false);
    }
 
    bool IsFullOutboundConn() const {
        return m_conn_type == ConnectionType::OUTBOUND_FULL_RELAY;
    }
 
    bool IsManualConn() const {
        return m_conn_type == ConnectionType::MANUAL;
    }
 
    bool IsBlockOnlyConn() const {
        return m_conn_type == ConnectionType::BLOCK_RELAY;
    }
 
    bool IsFeelerConn() const {
        return m_conn_type == ConnectionType::FEELER;
    }
 
    bool IsAddrFetchConn() const {
        return m_conn_type == ConnectionType::ADDR_FETCH;
    }
 
    bool IsInboundConn() const {
        return m_conn_type == ConnectionType::INBOUND;
    }
 
    bool ExpectServicesFromConn() const {
        switch (m_conn_type) {
            case ConnectionType::INBOUND:
            case ConnectionType::MANUAL:
            case ConnectionType::FEELER:
                return false;
            case ConnectionType::OUTBOUND_FULL_RELAY:
            case ConnectionType::BLOCK_RELAY:
            case ConnectionType::ADDR_FETCH:
                return true;
        } // no default case, so the compiler can warn about missing cases
 
        assert(false);
    }
 
    Network ConnectedThroughNetwork() const;
 
    // We selected peer as (compact blocks) high-bandwidth peer (BIP152)
    std::atomic<bool> m_bip152_highbandwidth_to{false};
    // Peer selected us as (compact blocks) high-bandwidth peer (BIP152)
    std::atomic<bool> m_bip152_highbandwidth_from{false};
 
    struct TxRelay {
        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){nullptr};
 
        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<uint256> 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{0s};
        std::chrono::microseconds nNextInvSend{0};
 
        std::atomic<CAmount> minFeeFilter{0};
        CAmount lastSentFeeFilter{0};
        std::chrono::microseconds m_next_send_feefilter{0};
    };
 
    // m_tx_relay == nullptr if we're not relaying transactions with this peer
    std::unique_ptr<TxRelay> m_tx_relay;
 
    std::atomic<std::chrono::seconds> m_last_block_time{0s};
 
    std::atomic<std::chrono::seconds> m_last_tx_time{0s};
 
    std::atomic<std::chrono::microseconds> m_last_ping_time{0us};
 
    std::atomic<std::chrono::microseconds> m_min_ping_time{std::chrono::microseconds::max()};
 
    CNode(NodeId id, ServiceFlags nLocalServicesIn, SOCKET hSocketIn, const CAddress& addrIn, uint64_t nKeyedNetGroupIn, uint64_t nLocalHostNonceIn, const CAddress& addrBindIn, const std::string& addrNameIn, ConnectionType conn_type_in, bool inbound_onion);
    ~CNode();
    CNode(const CNode&) = delete;
    CNode& operator=(const CNode&) = delete;
 
    NodeId GetId() const {
        return id;
    }
 
    uint64_t GetLocalNonce() const {
        return nLocalHostNonce;
    }
 
    int GetRefCount() const
    {
        assert(nRefCount >= 0);
        return nRefCount;
    }
 
    bool ReceiveMsgBytes(Span<const uint8_t> msg_bytes, bool& complete);
 
    void SetCommonVersion(int greatest_common_version)
    {
        Assume(m_greatest_common_version == INIT_PROTO_VERSION);
        m_greatest_common_version = greatest_common_version;
    }
    int GetCommonVersion() const
    {
        return m_greatest_common_version;
    }
 
    CService GetAddrLocal() const LOCKS_EXCLUDED(m_addr_local_mutex);
    void SetAddrLocal(const CService& addrLocalIn) LOCKS_EXCLUDED(m_addr_local_mutex);
 
    CNode* AddRef()
    {
        nRefCount++;
        return this;
    }
 
    void Release()
    {
        nRefCount--;
    }
 
    void AddKnownTx(const uint256& hash)
    {
        if (m_tx_relay != nullptr) {
            LOCK(m_tx_relay->cs_tx_inventory);
            m_tx_relay->filterInventoryKnown.insert(hash);
        }
    }
 
    void PushTxInventory(const uint256& hash)
    {
        if (m_tx_relay == nullptr) return;
        LOCK(m_tx_relay->cs_tx_inventory);
        if (!m_tx_relay->filterInventoryKnown.contains(hash)) {
            m_tx_relay->setInventoryTxToSend.insert(hash);
        }
    }
 
    void CloseSocketDisconnect();
 
    void CopyStats(CNodeStats& stats);
 
    ServiceFlags GetLocalServices() const
    {
        return nLocalServices;
    }
 
    std::string ConnectionTypeAsString() const { return ::ConnectionTypeAsString(m_conn_type); }
 
    void PongReceived(std::chrono::microseconds ping_time) {
        m_last_ping_time = ping_time;
        m_min_ping_time = std::min(m_min_ping_time.load(), ping_time);
    }
 
private:
    const NodeId id;
    const uint64_t nLocalHostNonce;
    const ConnectionType m_conn_type;
    std::atomic<int> m_greatest_common_version{INIT_PROTO_VERSION};
 
    const ServiceFlags nLocalServices;
 
    std::list<CNetMessage> vRecvMsg; // Used only by SocketHandler thread
 
    // Our address, as reported by the peer
    CService addrLocal GUARDED_BY(m_addr_local_mutex);
    mutable Mutex m_addr_local_mutex;
 
    mapMsgCmdSize mapSendBytesPerMsgCmd GUARDED_BY(cs_vSend);
    mapMsgCmdSize mapRecvBytesPerMsgCmd GUARDED_BY(cs_vRecv);
};
 
class NetEventsInterface
{
public:
    virtual void InitializeNode(CNode* pnode) = 0;
 
    virtual void FinalizeNode(const CNode& node) = 0;
 
    virtual bool ProcessMessages(CNode* pnode, std::atomic<bool>& interrupt) = 0;
 
    virtual bool SendMessages(CNode* pnode) EXCLUSIVE_LOCKS_REQUIRED(pnode->cs_sendProcessing) = 0;
 
 
protected:
    ~NetEventsInterface() = default;
};
 
class CConnman
{
public:
 
    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;
        CClientUIInterface* uiInterface = nullptr;
        NetEventsInterface* m_msgproc = nullptr;
        BanMan* m_banman = nullptr;
        unsigned int nSendBufferMaxSize = 0;
        unsigned int nReceiveFloodSize = 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;
        std::vector<CService> onion_binds;
        bool bind_on_any;
        bool m_use_addrman_outgoing = true;
        std::vector<std::string> m_specified_outgoing;
        std::vector<std::string> m_added_nodes;
        bool m_i2p_accept_incoming;
    };
 
    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;
        m_client_interface = connOptions.uiInterface;
        m_banman = connOptions.m_banman;
        m_msgproc = connOptions.m_msgproc;
        nSendBufferMaxSize = connOptions.nSendBufferMaxSize;
        nReceiveFloodSize = connOptions.nReceiveFloodSize;
        m_peer_connect_timeout = std::chrono::seconds{connOptions.m_peer_connect_timeout};
        {
            LOCK(cs_totalBytesSent);
            nMaxOutboundLimit = connOptions.nMaxOutboundLimit;
        }
        vWhitelistedRange = connOptions.vWhitelistedRange;
        {
            LOCK(m_added_nodes_mutex);
            m_added_nodes = connOptions.m_added_nodes;
        }
        m_onion_binds = connOptions.onion_binds;
    }
 
    CConnman(uint64_t seed0, uint64_t seed1, AddrMan& addrman, bool network_active = true);
    ~CConnman();
    bool Start(CScheduler& scheduler, const Options& options);
 
    void StopThreads();
    void StopNodes();
    void Stop()
    {
        StopThreads();
        StopNodes();
    };
 
    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, const char* strDest, ConnectionType conn_type);
    bool CheckIncomingNonce(uint64_t nonce);
 
    bool ForNode(NodeId id, std::function<bool(CNode* pnode)> func);
 
    void PushMessage(CNode* pnode, CSerializedNetMsg&& msg);
 
    using NodeFn = std::function<void(CNode*)>;
    void ForEachNode(const NodeFn& func)
    {
        LOCK(m_nodes_mutex);
        for (auto&& node : m_nodes) {
            if (NodeFullyConnected(node))
                func(node);
        }
    };
 
    void ForEachNode(const NodeFn& func) const
    {
        LOCK(m_nodes_mutex);
        for (auto&& node : m_nodes) {
            if (NodeFullyConnected(node))
                func(node);
        }
    };
 
    // Addrman functions
    std::vector<CAddress> GetAddresses(size_t max_addresses, size_t max_pct, std::optional<Network> network) const;
    std::vector<CAddress> GetAddresses(CNode& requestor, size_t max_addresses, size_t max_pct);
 
    // 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() const;
 
    void StartExtraBlockRelayPeers() {
        LogPrint(BCLog::NET, "net: enabling extra block-relay-only peers\n");
        m_start_extra_block_relay_peers = true;
    }
 
    // 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 GetExtraFullOutboundCount() const;
    // Count the number of block-relay-only peers we have over our limit.
    int GetExtraBlockRelayCount() const;
 
    bool AddNode(const std::string& node);
    bool RemoveAddedNode(const std::string& node);
    std::vector<AddedNodeInfo> GetAddedNodeInfo() const;
 
    bool AddConnection(const std::string& address, ConnectionType conn_type);
 
    size_t GetNodeCount(ConnectionDirection) const;
    void GetNodeStats(std::vector<CNodeStats>& vstats) const;
    bool DisconnectNode(const std::string& node);
    bool DisconnectNode(const CSubNet& subnet);
    bool DisconnectNode(const CNetAddr& addr);
    bool DisconnectNode(NodeId id);
 
    ServiceFlags GetLocalServices() const;
 
    uint64_t GetMaxOutboundTarget() const;
    std::chrono::seconds GetMaxOutboundTimeframe() const;
 
    bool OutboundTargetReached(bool historicalBlockServingLimit) const;
 
    uint64_t GetOutboundTargetBytesLeft() const;
 
    std::chrono::seconds GetMaxOutboundTimeLeftInCycle() const;
 
    uint64_t GetTotalBytesRecv() const;
    uint64_t GetTotalBytesSent() const;
 
    CSipHasher GetDeterministicRandomizer(uint64_t id) const;
 
    unsigned int GetReceiveFloodSize() const;
 
    void WakeMessageHandler();
 
    bool ShouldRunInactivityChecks(const CNode& node, std::chrono::seconds now) const;
 
private:
    struct ListenSocket {
    public:
        std::shared_ptr<Sock> sock;
        inline void AddSocketPermissionFlags(NetPermissionFlags& flags) const { NetPermissions::AddFlag(flags, m_permissions); }
        ListenSocket(std::shared_ptr<Sock> sock_, NetPermissionFlags permissions_)
            : sock{sock_}, 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 Options& options);
 
    void ThreadOpenAddedConnections();
    void AddAddrFetch(const std::string& strDest);
    void ProcessAddrFetch();
    void ThreadOpenConnections(std::vector<std::string> connect);
    void ThreadMessageHandler();
    void ThreadI2PAcceptIncoming();
    void AcceptConnection(const ListenSocket& hListenSocket);
 
    void CreateNodeFromAcceptedSocket(std::unique_ptr<Sock>&& sock,
                                      NetPermissionFlags permissionFlags,
                                      const CAddress& addr_bind,
                                      const CAddress& addr);
 
    void DisconnectNodes();
    void NotifyNumConnectionsChanged();
    bool InactivityCheck(const CNode& node) const;
 
    bool GenerateSelectSet(const std::vector<CNode*>& nodes,
                           std::set<SOCKET>& recv_set,
                           std::set<SOCKET>& send_set,
                           std::set<SOCKET>& error_set);
 
    void SocketEvents(const std::vector<CNode*>& nodes,
                      std::set<SOCKET>& recv_set,
                      std::set<SOCKET>& send_set,
                      std::set<SOCKET>& error_set);
 
    void SocketHandler();
 
    void SocketHandlerConnected(const std::vector<CNode*>& nodes,
                                const std::set<SOCKET>& recv_set,
                                const std::set<SOCKET>& send_set,
                                const std::set<SOCKET>& error_set);
 
    void SocketHandlerListening(const std::set<SOCKET>& recv_set);
 
    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 AlreadyConnectedToAddress(const CAddress& addr);
 
    bool AttemptToEvictConnection();
    CNode* ConnectNode(CAddress addrConnect, const char *pszDest, bool fCountFailure, ConnectionType conn_type);
    void AddWhitelistPermissionFlags(NetPermissionFlags& flags, const CNetAddr &addr) const;
 
    void DeleteNode(CNode* pnode);
 
    NodeId GetNewNodeId();
 
    size_t SocketSendData(CNode& node) const EXCLUSIVE_LOCKS_REQUIRED(node.cs_vSend);
    void DumpAddresses();
 
    // Network stats
    void RecordBytesRecv(uint64_t bytes);
    void RecordBytesSent(uint64_t bytes);
 
    std::vector<CAddress> GetCurrentBlockRelayOnlyConns() const;
 
    // Whether the node should be passed out in ForEach* callbacks
    static bool NodeFullyConnected(const CNode* pnode);
 
    // Network usage totals
    mutable RecursiveMutex cs_totalBytesSent;
    std::atomic<uint64_t> nTotalBytesRecv{0};
    uint64_t nTotalBytesSent GUARDED_BY(cs_totalBytesSent) {0};
 
    // outbound limit & stats
    uint64_t nMaxOutboundTotalBytesSentInCycle GUARDED_BY(cs_totalBytesSent) {0};
    std::chrono::seconds nMaxOutboundCycleStartTime GUARDED_BY(cs_totalBytesSent) {0};
    uint64_t nMaxOutboundLimit GUARDED_BY(cs_totalBytesSent);
 
    // P2P timeout in seconds
    std::chrono::seconds 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};
    AddrMan& addrman;
    std::deque<std::string> m_addr_fetches GUARDED_BY(m_addr_fetches_mutex);
    Mutex m_addr_fetches_mutex;
    std::vector<std::string> m_added_nodes GUARDED_BY(m_added_nodes_mutex);
    mutable Mutex m_added_nodes_mutex;
    std::vector<CNode*> m_nodes GUARDED_BY(m_nodes_mutex);
    std::list<CNode*> m_nodes_disconnected;
    mutable RecursiveMutex m_nodes_mutex;
    std::atomic<NodeId> nLastNodeId{0};
    unsigned int nPrevNodeCount{0};
 
    struct CachedAddrResponse {
        std::vector<CAddress> m_addrs_response_cache;
        std::chrono::microseconds m_cache_entry_expiration{0};
    };
 
    std::map<uint64_t, CachedAddrResponse> m_addr_response_caches;
 
    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;
    CClientUIInterface* m_client_interface;
    NetEventsInterface* m_msgproc;
    BanMan* m_banman;
 
    std::vector<CAddress> m_anchors;
 
    const uint64_t nSeed0, nSeed1;
 
    bool fMsgProcWake GUARDED_BY(mutexMsgProc);
 
    std::condition_variable condMsgProc;
    Mutex mutexMsgProc;
    std::atomic<bool> flagInterruptMsgProc{false};
 
    CThreadInterrupt interruptNet;
 
    std::unique_ptr<i2p::sam::Session> m_i2p_sam_session;
 
    std::thread threadDNSAddressSeed;
    std::thread threadSocketHandler;
    std::thread threadOpenAddedConnections;
    std::thread threadOpenConnections;
    std::thread threadMessageHandler;
    std::thread threadI2PAcceptIncoming;
 
    std::atomic_bool m_try_another_outbound_peer;
 
    std::atomic_bool m_start_extra_block_relay_peers{false};
 
    std::vector<CService> m_onion_binds;
 
    class NodesSnapshot
    {
    public:
        explicit NodesSnapshot(const CConnman& connman, bool shuffle)
        {
            {
                LOCK(connman.m_nodes_mutex);
                m_nodes_copy = connman.m_nodes;
                for (auto& node : m_nodes_copy) {
                    node->AddRef();
                }
            }
            if (shuffle) {
                Shuffle(m_nodes_copy.begin(), m_nodes_copy.end(), FastRandomContext{});
            }
        }
 
        ~NodesSnapshot()
        {
            for (auto& node : m_nodes_copy) {
                node->Release();
            }
        }
 
        const std::vector<CNode*>& Nodes() const
        {
            return m_nodes_copy;
        }
 
    private:
        std::vector<CNode*> m_nodes_copy;
    };
 
    friend struct CConnmanTest;
    friend struct ConnmanTestMsg;
};
 
void CaptureMessage(const CAddress& addr, const std::string& msg_type, const Span<const unsigned char>& data, bool is_incoming);
 
struct NodeEvictionCandidate
{
    NodeId id;
    std::chrono::seconds m_connected;
    std::chrono::microseconds m_min_ping_time;
    std::chrono::seconds m_last_block_time;
    std::chrono::seconds m_last_tx_time;
    bool fRelevantServices;
    bool fRelayTxes;
    bool fBloomFilter;
    uint64_t nKeyedNetGroup;
    bool prefer_evict;
    bool m_is_local;
    Network m_network;
};
 
[[nodiscard]] std::optional<NodeId> SelectNodeToEvict(std::vector<NodeEvictionCandidate>&& vEvictionCandidates);
 
void ProtectEvictionCandidatesByRatio(std::vector<NodeEvictionCandidate>& vEvictionCandidates);
 
#endif // BITCOIN_NET_H