node.go

package node

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"net"
	"net/http"
	_ "net/http/pprof"
	"strings"
	"time"

	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promhttp"

	amino "github.com/tendermint/go-amino"
	abci "github.com/tendermint/tendermint/abci/types"
	bc "github.com/tendermint/tendermint/blockchain"
	cfg "github.com/tendermint/tendermint/config"
	cs "github.com/tendermint/tendermint/consensus"
	"github.com/tendermint/tendermint/crypto/ed25519"
	"github.com/tendermint/tendermint/evidence"
	cmn "github.com/tendermint/tendermint/libs/common"
	dbm "github.com/tendermint/tendermint/libs/db"
	"github.com/tendermint/tendermint/libs/log"
	mempl "github.com/tendermint/tendermint/mempool"
	"github.com/tendermint/tendermint/p2p"
	"github.com/tendermint/tendermint/p2p/pex"
	"github.com/tendermint/tendermint/privval"
	"github.com/tendermint/tendermint/proxy"
	rpccore "github.com/tendermint/tendermint/rpc/core"
	ctypes "github.com/tendermint/tendermint/rpc/core/types"
	grpccore "github.com/tendermint/tendermint/rpc/grpc"
	"github.com/tendermint/tendermint/rpc/lib/server"
	sm "github.com/tendermint/tendermint/state"
	"github.com/tendermint/tendermint/state/txindex"
	"github.com/tendermint/tendermint/state/txindex/kv"
	"github.com/tendermint/tendermint/state/txindex/null"
	"github.com/tendermint/tendermint/types"
	tmtime "github.com/tendermint/tendermint/types/time"
	"github.com/tendermint/tendermint/version"
)

//------------------------------------------------------------------------------

// DBContext specifies config information for loading a new DB.
type DBContext struct {
	ID     string
	Config *cfg.Config
}

// DBProvider takes a DBContext and returns an instantiated DB.
type DBProvider func(*DBContext) (dbm.DB, error)

// DefaultDBProvider returns a database using the DBBackend and DBDir
// specified in the ctx.Config.
func DefaultDBProvider(ctx *DBContext) (dbm.DB, error) {
	dbType := dbm.DBBackendType(ctx.Config.DBBackend)
	return dbm.NewDB(ctx.ID, dbType, ctx.Config.DBDir()), nil
}

// GenesisDocProvider returns a GenesisDoc.
// It allows the GenesisDoc to be pulled from sources other than the
// filesystem, for instance from a distributed key-value store cluster.
type GenesisDocProvider func() (*types.GenesisDoc, error)

// DefaultGenesisDocProviderFunc returns a GenesisDocProvider that loads
// the GenesisDoc from the config.GenesisFile() on the filesystem.
func DefaultGenesisDocProviderFunc(config *cfg.Config) GenesisDocProvider {
	return func() (*types.GenesisDoc, error) {
		return types.GenesisDocFromFile(config.GenesisFile())
	}
}

// NodeProvider takes a config and a logger and returns a ready to go Node.
type NodeProvider func(*cfg.Config, log.Logger) (*Node, error)

// DefaultNewNode returns a Tendermint node with default settings for the
// PrivValidator, ClientCreator, GenesisDoc, and DBProvider.
// It implements NodeProvider.
func DefaultNewNode(config *cfg.Config, logger log.Logger) (*Node, error) {
	// Generate node PrivKey
	nodeKey, err := p2p.LoadOrGenNodeKey(config.NodeKeyFile())
	if err != nil {
		return nil, err
	}
	return NewNode(config,
		privval.LoadOrGenFilePV(config.PrivValidatorFile()),
		nodeKey,
		proxy.DefaultClientCreator(config.ProxyApp, config.ABCI, config.DBDir()),
		DefaultGenesisDocProviderFunc(config),
		DefaultDBProvider,
		DefaultMetricsProvider(config.Instrumentation),
		logger,
	)
}

// MetricsProvider returns a consensus, p2p and mempool Metrics.
type MetricsProvider func() (*cs.Metrics, *p2p.Metrics, *mempl.Metrics, *sm.Metrics)

// DefaultMetricsProvider returns Metrics build using Prometheus client library
// if Prometheus is enabled. Otherwise, it returns no-op Metrics.
func DefaultMetricsProvider(config *cfg.InstrumentationConfig) MetricsProvider {
	return func() (*cs.Metrics, *p2p.Metrics, *mempl.Metrics, *sm.Metrics) {
		if config.Prometheus {
			return cs.PrometheusMetrics(config.Namespace), p2p.PrometheusMetrics(config.Namespace),
				mempl.PrometheusMetrics(config.Namespace), sm.PrometheusMetrics(config.Namespace)
		}
		return cs.NopMetrics(), p2p.NopMetrics(), mempl.NopMetrics(), sm.NopMetrics()
	}
}

//------------------------------------------------------------------------------

// Node is the highest level interface to a full Tendermint node.
// It includes all configuration information and running services.
type Node struct {
	cmn.BaseService

	// config
	config        *cfg.Config
	genesisDoc    *types.GenesisDoc   // initial validator set
	privValidator types.PrivValidator // local node's validator key

	// network
	transport   *p2p.MultiplexTransport
	sw          *p2p.Switch  // p2p connections
	addrBook    pex.AddrBook // known peers
	nodeInfo    p2p.NodeInfo
	nodeKey     *p2p.NodeKey // our node privkey
	isListening bool

	// services
	eventBus         *types.EventBus // pub/sub for services
	stateDB          dbm.DB
	blockStore       *bc.BlockStore         // store the blockchain to disk
	bcReactor        *bc.BlockchainReactor  // for fast-syncing
	mempoolReactor   *mempl.MempoolReactor  // for gossipping transactions
	consensusState   *cs.ConsensusState     // latest consensus state
	consensusReactor *cs.ConsensusReactor   // for participating in the consensus
	evidencePool     *evidence.EvidencePool // tracking evidence
	proxyApp         proxy.AppConns         // connection to the application
	rpcListeners     []net.Listener         // rpc servers
	txIndexer        txindex.TxIndexer
	indexerService   *txindex.IndexerService
	prometheusSrv    *http.Server
}

// NewNode returns a new, ready to go, Tendermint Node.
func NewNode(config *cfg.Config,
	privValidator types.PrivValidator,
	nodeKey *p2p.NodeKey,
	clientCreator proxy.ClientCreator,
	genesisDocProvider GenesisDocProvider,
	dbProvider DBProvider,
	metricsProvider MetricsProvider,
	logger log.Logger) (*Node, error) {

	// Get BlockStore
	blockStoreDB, err := dbProvider(&DBContext{"blockstore", config})
	if err != nil {
		return nil, err
	}
	blockStore := bc.NewBlockStore(blockStoreDB)

	// Get State
	stateDB, err := dbProvider(&DBContext{"state", config})
	if err != nil {
		return nil, err
	}

	// Get genesis doc
	// TODO: move to state package?
	genDoc, err := loadGenesisDoc(stateDB)
	if err != nil {
		genDoc, err = genesisDocProvider()
		if err != nil {
			return nil, err
		}
		// save genesis doc to prevent a certain class of user errors (e.g. when it
		// was changed, accidentally or not). Also good for audit trail.
		saveGenesisDoc(stateDB, genDoc)
	}

	state, err := sm.LoadStateFromDBOrGenesisDoc(stateDB, genDoc)
	if err != nil {
		return nil, err
	}

	// Create the proxyApp and establish connections to the ABCI app (consensus, mempool, query).
	proxyApp := proxy.NewAppConns(clientCreator)
	proxyApp.SetLogger(logger.With("module", "proxy"))
	if err := proxyApp.Start(); err != nil {
		return nil, fmt.Errorf("Error starting proxy app connections: %v", err)
	}

	// Create the handshaker, which calls RequestInfo, sets the AppVersion on the state,
	// and replays any blocks as necessary to sync tendermint with the app.
	consensusLogger := logger.With("module", "consensus")
	handshaker := cs.NewHandshaker(stateDB, state, blockStore, genDoc)
	handshaker.SetLogger(consensusLogger)
	if err := handshaker.Handshake(proxyApp); err != nil {
		return nil, fmt.Errorf("Error during handshake: %v", err)
	}

	// Reload the state. It will have the Version.Consensus.App set by the
	// Handshake, and may have other modifications as well (ie. depending on
	// what happened during block replay).
	state = sm.LoadState(stateDB)

	// Ensure the state's block version matches that of the software.
	if state.Version.Consensus.Block != version.BlockProtocol {
		return nil, fmt.Errorf(
			"Block version of the software does not match that of the state.\n"+
				"Got version.BlockProtocol=%v, state.Version.Consensus.Block=%v",
			version.BlockProtocol,
			state.Version.Consensus.Block,
		)
	}

	// If an address is provided, listen on the socket for a
	// connection from an external signing process.
	if config.PrivValidatorListenAddr != "" {
		var (
			// TODO: persist this key so external signer
			// can actually authenticate us
			privKey = ed25519.GenPrivKey()
			pvsc    = privval.NewTCPVal(
				logger.With("module", "privval"),
				config.PrivValidatorListenAddr,
				privKey,
			)
		)

		if err := pvsc.Start(); err != nil {
			return nil, fmt.Errorf("Error starting private validator client: %v", err)
		}

		privValidator = pvsc
	}

	// Decide whether to fast-sync or not
	// We don't fast-sync when the only validator is us.
	fastSync := config.FastSync
	if state.Validators.Size() == 1 {
		addr, _ := state.Validators.GetByIndex(0)
		if bytes.Equal(privValidator.GetAddress(), addr) {
			fastSync = false
		}
	}

	// Log whether this node is a validator or an observer
	if state.Validators.HasAddress(privValidator.GetAddress()) {
		consensusLogger.Info("This node is a validator", "addr", privValidator.GetAddress(), "pubKey", privValidator.GetPubKey())
	} else {
		consensusLogger.Info("This node is not a validator", "addr", privValidator.GetAddress(), "pubKey", privValidator.GetPubKey())
	}

	csMetrics, p2pMetrics, memplMetrics, smMetrics := metricsProvider()

	// Make MempoolReactor
	mempool := mempl.NewMempool(
		config.Mempool,
		proxyApp.Mempool(),
		state.LastBlockHeight,
		mempl.WithMetrics(memplMetrics),
		mempl.WithPreCheck(
			mempl.PreCheckAminoMaxBytes(
				types.MaxDataBytesUnknownEvidence(
					state.ConsensusParams.BlockSize.MaxBytes,
					state.Validators.Size(),
				),
			),
		),
		mempl.WithPostCheck(
			mempl.PostCheckMaxGas(state.ConsensusParams.BlockSize.MaxGas),
		),
	)
	mempoolLogger := logger.With("module", "mempool")
	mempool.SetLogger(mempoolLogger)
	if config.Mempool.WalEnabled() {
		mempool.InitWAL() // no need to have the mempool wal during tests
	}
	mempoolReactor := mempl.NewMempoolReactor(config.Mempool, mempool)
	mempoolReactor.SetLogger(mempoolLogger)

	if config.Consensus.WaitForTxs() {
		mempool.EnableTxsAvailable()
	}

	// Make Evidence Reactor
	evidenceDB, err := dbProvider(&DBContext{"evidence", config})
	if err != nil {
		return nil, err
	}
	evidenceLogger := logger.With("module", "evidence")
	evidenceStore := evidence.NewEvidenceStore(evidenceDB)
	evidencePool := evidence.NewEvidencePool(stateDB, evidenceStore)
	evidencePool.SetLogger(evidenceLogger)
	evidenceReactor := evidence.NewEvidenceReactor(evidencePool)
	evidenceReactor.SetLogger(evidenceLogger)

	blockExecLogger := logger.With("module", "state")
	// make block executor for consensus and blockchain reactors to execute blocks
	blockExec := sm.NewBlockExecutor(
		stateDB,
		blockExecLogger,
		proxyApp.Consensus(),
		mempool,
		evidencePool,
		sm.BlockExecutorWithMetrics(smMetrics),
	)

	// Make BlockchainReactor
	bcReactor := bc.NewBlockchainReactor(state.Copy(), blockExec, blockStore, fastSync)
	bcReactor.SetLogger(logger.With("module", "blockchain"))

	// Make ConsensusReactor
	consensusState := cs.NewConsensusState(
		config.Consensus,
		state.Copy(),
		blockExec,
		blockStore,
		mempool,
		evidencePool,
		cs.StateMetrics(csMetrics),
	)
	consensusState.SetLogger(consensusLogger)
	if privValidator != nil {
		consensusState.SetPrivValidator(privValidator)
	}
	consensusReactor := cs.NewConsensusReactor(consensusState, fastSync, cs.ReactorMetrics(csMetrics))
	consensusReactor.SetLogger(consensusLogger)

	eventBus := types.NewEventBus()
	eventBus.SetLogger(logger.With("module", "events"))

	// services which will be publishing and/or subscribing for messages (events)
	// consensusReactor will set it on consensusState and blockExecutor
	consensusReactor.SetEventBus(eventBus)

	// Transaction indexing
	var txIndexer txindex.TxIndexer
	switch config.TxIndex.Indexer {
	case "kv":
		store, err := dbProvider(&DBContext{"tx_index", config})
		if err != nil {
			return nil, err
		}
		if config.TxIndex.IndexTags != "" {
			txIndexer = kv.NewTxIndex(store, kv.IndexTags(splitAndTrimEmpty(config.TxIndex.IndexTags, ",", " ")))
		} else if config.TxIndex.IndexAllTags {
			txIndexer = kv.NewTxIndex(store, kv.IndexAllTags())
		} else {
			txIndexer = kv.NewTxIndex(store)
		}
	default:
		txIndexer = &null.TxIndex{}
	}

	indexerService := txindex.NewIndexerService(txIndexer, eventBus)
	indexerService.SetLogger(logger.With("module", "txindex"))

	var (
		p2pLogger = logger.With("module", "p2p")
		nodeInfo  = makeNodeInfo(
			config,
			nodeKey.ID(),
			txIndexer,
			genDoc.ChainID,
			p2p.NewProtocolVersion(
				version.P2PProtocol, // global
				state.Version.Consensus.Block,
				state.Version.Consensus.App,
			),
		)
	)

	// Setup Transport.
	var (
		transport   = p2p.NewMultiplexTransport(nodeInfo, *nodeKey)
		connFilters = []p2p.ConnFilterFunc{}
		peerFilters = []p2p.PeerFilterFunc{}
	)

	if !config.P2P.AllowDuplicateIP {
		connFilters = append(connFilters, p2p.ConnDuplicateIPFilter())
	}

	// Filter peers by addr or pubkey with an ABCI query.
	// If the query return code is OK, add peer.
	if config.FilterPeers {
		connFilters = append(
			connFilters,
			// ABCI query for address filtering.
			func(_ p2p.ConnSet, c net.Conn, _ []net.IP) error {
				res, err := proxyApp.Query().QuerySync(abci.RequestQuery{
					Path: fmt.Sprintf("/p2p/filter/addr/%s", c.RemoteAddr().String()),
				})
				if err != nil {
					return err
				}
				if res.IsErr() {
					return fmt.Errorf("Error querying abci app: %v", res)
				}

				return nil
			},
		)

		peerFilters = append(
			peerFilters,
			// ABCI query for ID filtering.
			func(_ p2p.IPeerSet, p p2p.Peer) error {
				res, err := proxyApp.Query().QuerySync(abci.RequestQuery{
					Path: fmt.Sprintf("/p2p/filter/id/%s", p.ID()),
				})
				if err != nil {
					return err
				}
				if res.IsErr() {
					return fmt.Errorf("Error querying abci app: %v", res)
				}

				return nil
			},
		)
	}

	p2p.MultiplexTransportConnFilters(connFilters...)(transport)

	// Setup Switch.
	sw := p2p.NewSwitch(
		config.P2P,
		transport,
		p2p.WithMetrics(p2pMetrics),
		p2p.SwitchPeerFilters(peerFilters...),
	)
	sw.SetLogger(p2pLogger)
	sw.AddReactor("MEMPOOL", mempoolReactor)
	sw.AddReactor("BLOCKCHAIN", bcReactor)
	sw.AddReactor("CONSENSUS", consensusReactor)
	sw.AddReactor("EVIDENCE", evidenceReactor)
	sw.SetNodeInfo(nodeInfo)
	sw.SetNodeKey(nodeKey)

	p2pLogger.Info("P2P Node ID", "ID", nodeKey.ID(), "file", config.NodeKeyFile())

	// Optionally, start the pex reactor
	//
	// TODO:
	//
	// We need to set Seeds and PersistentPeers on the switch,
	// since it needs to be able to use these (and their DNS names)
	// even if the PEX is off. We can include the DNS name in the NetAddress,
	// but it would still be nice to have a clear list of the current "PersistentPeers"
	// somewhere that we can return with net_info.
	//
	// If PEX is on, it should handle dialing the seeds. Otherwise the switch does it.
	// Note we currently use the addrBook regardless at least for AddOurAddress
	addrBook := pex.NewAddrBook(config.P2P.AddrBookFile(), config.P2P.AddrBookStrict)

	// Add ourselves to addrbook to prevent dialing ourselves
	addrBook.AddOurAddress(nodeInfo.NetAddress())

	addrBook.SetLogger(p2pLogger.With("book", config.P2P.AddrBookFile()))
	if config.P2P.PexReactor {
		// TODO persistent peers ? so we can have their DNS addrs saved
		pexReactor := pex.NewPEXReactor(addrBook,
			&pex.PEXReactorConfig{
				Seeds:    splitAndTrimEmpty(config.P2P.Seeds, ",", " "),
				SeedMode: config.P2P.SeedMode,
			})
		pexReactor.SetLogger(p2pLogger)
		sw.AddReactor("PEX", pexReactor)
	}

	sw.SetAddrBook(addrBook)

	// run the profile server
	profileHost := config.ProfListenAddress
	if profileHost != "" {
		go func() {
			logger.Error("Profile server", "err", http.ListenAndServe(profileHost, nil))
		}()
	}

	node := &Node{
		config:        config,
		genesisDoc:    genDoc,
		privValidator: privValidator,

		transport: transport,
		sw:        sw,
		addrBook:  addrBook,
		nodeInfo:  nodeInfo,
		nodeKey:   nodeKey,

		stateDB:          stateDB,
		blockStore:       blockStore,
		bcReactor:        bcReactor,
		mempoolReactor:   mempoolReactor,
		consensusState:   consensusState,
		consensusReactor: consensusReactor,
		evidencePool:     evidencePool,
		proxyApp:         proxyApp,
		txIndexer:        txIndexer,
		indexerService:   indexerService,
		eventBus:         eventBus,
	}
	node.BaseService = *cmn.NewBaseService(logger, "Node", node)
	return node, nil
}

// OnStart starts the Node. It implements cmn.Service.
func (n *Node) OnStart() error {
	now := tmtime.Now()
	genTime := n.genesisDoc.GenesisTime
	if genTime.After(now) {
		n.Logger.Info("Genesis time is in the future. Sleeping until then...", "genTime", genTime)
		time.Sleep(genTime.Sub(now))
	}

	err := n.eventBus.Start()
	if err != nil {
		return err
	}

	// Add private IDs to addrbook to block those peers being added
	n.addrBook.AddPrivateIDs(splitAndTrimEmpty(n.config.P2P.PrivatePeerIDs, ",", " "))

	// Start the RPC server before the P2P server
	// so we can eg. receive txs for the first block
	if n.config.RPC.ListenAddress != "" {
		listeners, err := n.startRPC()
		if err != nil {
			return err
		}
		n.rpcListeners = listeners
	}

	if n.config.Instrumentation.Prometheus &&
		n.config.Instrumentation.PrometheusListenAddr != "" {
		n.prometheusSrv = n.startPrometheusServer(n.config.Instrumentation.PrometheusListenAddr)
	}

	// Start the transport.
	addr, err := p2p.NewNetAddressStringWithOptionalID(n.config.P2P.ListenAddress)
	if err != nil {
		return err
	}
	if err := n.transport.Listen(*addr); err != nil {
		return err
	}

	n.isListening = true

	// Start the switch (the P2P server).
	err = n.sw.Start()
	if err != nil {
		return err
	}

	// Always connect to persistent peers
	if n.config.P2P.PersistentPeers != "" {
		err = n.sw.DialPeersAsync(n.addrBook, splitAndTrimEmpty(n.config.P2P.PersistentPeers, ",", " "), true)
		if err != nil {
			return err
		}
	}

	// start tx indexer
	return n.indexerService.Start()
}

// OnStop stops the Node. It implements cmn.Service.
func (n *Node) OnStop() {
	n.BaseService.OnStop()

	n.Logger.Info("Stopping Node")

	// first stop the non-reactor services
	n.eventBus.Stop()
	n.indexerService.Stop()

	// now stop the reactors
	// TODO: gracefully disconnect from peers.
	n.sw.Stop()

	// stop mempool WAL
	if n.config.Mempool.WalEnabled() {
		n.mempoolReactor.Mempool.CloseWAL()
	}

	if err := n.transport.Close(); err != nil {
		n.Logger.Error("Error closing transport", "err", err)
	}

	n.isListening = false

	// finally stop the listeners / external services
	for _, l := range n.rpcListeners {
		n.Logger.Info("Closing rpc listener", "listener", l)
		if err := l.Close(); err != nil {
			n.Logger.Error("Error closing listener", "listener", l, "err", err)
		}
	}

	if pvsc, ok := n.privValidator.(*privval.TCPVal); ok {
		if err := pvsc.Stop(); err != nil {
			n.Logger.Error("Error stopping priv validator socket client", "err", err)
		}
	}

	if n.prometheusSrv != nil {
		if err := n.prometheusSrv.Shutdown(context.Background()); err != nil {
			// Error from closing listeners, or context timeout:
			n.Logger.Error("Prometheus HTTP server Shutdown", "err", err)
		}
	}
}

// ConfigureRPC sets all variables in rpccore so they will serve
// rpc calls from this node
func (n *Node) ConfigureRPC() {
	rpccore.SetStateDB(n.stateDB)
	rpccore.SetBlockStore(n.blockStore)
	rpccore.SetConsensusState(n.consensusState)
	rpccore.SetMempool(n.mempoolReactor.Mempool)
	rpccore.SetEvidencePool(n.evidencePool)
	rpccore.SetP2PPeers(n.sw)
	rpccore.SetP2PTransport(n)
	rpccore.SetPubKey(n.privValidator.GetPubKey())
	rpccore.SetGenesisDoc(n.genesisDoc)
	rpccore.SetAddrBook(n.addrBook)
	rpccore.SetProxyAppQuery(n.proxyApp.Query())
	rpccore.SetTxIndexer(n.txIndexer)
	rpccore.SetConsensusReactor(n.consensusReactor)
	rpccore.SetEventBus(n.eventBus)
	rpccore.SetLogger(n.Logger.With("module", "rpc"))
}

func (n *Node) startRPC() ([]net.Listener, error) {
	n.ConfigureRPC()
	listenAddrs := splitAndTrimEmpty(n.config.RPC.ListenAddress, ",", " ")
	coreCodec := amino.NewCodec()
	ctypes.RegisterAmino(coreCodec)

	if n.config.RPC.Unsafe {
		rpccore.AddUnsafeRoutes()
	}

	// we may expose the rpc over both a unix and tcp socket
	listeners := make([]net.Listener, len(listenAddrs))
	for i, listenAddr := range listenAddrs {
		mux := http.NewServeMux()
		rpcLogger := n.Logger.With("module", "rpc-server")
		wm := rpcserver.NewWebsocketManager(rpccore.Routes, coreCodec, rpcserver.EventSubscriber(n.eventBus))
		wm.SetLogger(rpcLogger.With("protocol", "websocket"))
		mux.HandleFunc("/websocket", wm.WebsocketHandler)
		rpcserver.RegisterRPCFuncs(mux, rpccore.Routes, coreCodec, rpcLogger)
		listener, err := rpcserver.StartHTTPServer(
			listenAddr,
			mux,
			rpcLogger,
			rpcserver.Config{MaxOpenConnections: n.config.RPC.MaxOpenConnections},
		)
		if err != nil {
			return nil, err
		}
		listeners[i] = listener
	}

	// we expose a simplified api over grpc for convenience to app devs
	grpcListenAddr := n.config.RPC.GRPCListenAddress
	if grpcListenAddr != "" {
		listener, err := grpccore.StartGRPCServer(
			grpcListenAddr,
			grpccore.Config{
				MaxOpenConnections: n.config.RPC.GRPCMaxOpenConnections,
			},
		)
		if err != nil {
			return nil, err
		}
		listeners = append(listeners, listener)
	}

	return listeners, nil
}

// startPrometheusServer starts a Prometheus HTTP server, listening for metrics
// collectors on addr.
func (n *Node) startPrometheusServer(addr string) *http.Server {
	srv := &http.Server{
		Addr: addr,
		Handler: promhttp.InstrumentMetricHandler(
			prometheus.DefaultRegisterer, promhttp.HandlerFor(
				prometheus.DefaultGatherer,
				promhttp.HandlerOpts{MaxRequestsInFlight: n.config.Instrumentation.MaxOpenConnections},
			),
		),
	}
	go func() {
		if err := srv.ListenAndServe(); err != http.ErrServerClosed {
			// Error starting or closing listener:
			n.Logger.Error("Prometheus HTTP server ListenAndServe", "err", err)
		}
	}()
	return srv
}

// Switch returns the Node's Switch.
func (n *Node) Switch() *p2p.Switch {
	return n.sw
}

// BlockStore returns the Node's BlockStore.
func (n *Node) BlockStore() *bc.BlockStore {
	return n.blockStore
}

// ConsensusState returns the Node's ConsensusState.
func (n *Node) ConsensusState() *cs.ConsensusState {
	return n.consensusState
}

// ConsensusReactor returns the Node's ConsensusReactor.
func (n *Node) ConsensusReactor() *cs.ConsensusReactor {
	return n.consensusReactor
}

// MempoolReactor returns the Node's MempoolReactor.
func (n *Node) MempoolReactor() *mempl.MempoolReactor {
	return n.mempoolReactor
}

// EvidencePool returns the Node's EvidencePool.
func (n *Node) EvidencePool() *evidence.EvidencePool {
	return n.evidencePool
}

// EventBus returns the Node's EventBus.
func (n *Node) EventBus() *types.EventBus {
	return n.eventBus
}

// PrivValidator returns the Node's PrivValidator.
// XXX: for convenience only!
func (n *Node) PrivValidator() types.PrivValidator {
	return n.privValidator
}

// GenesisDoc returns the Node's GenesisDoc.
func (n *Node) GenesisDoc() *types.GenesisDoc {
	return n.genesisDoc
}

// ProxyApp returns the Node's AppConns, representing its connections to the ABCI application.
func (n *Node) ProxyApp() proxy.AppConns {
	return n.proxyApp
}

//------------------------------------------------------------------------------

func (n *Node) Listeners() []string {
	return []string{
		fmt.Sprintf("Listener(@%v)", n.config.P2P.ExternalAddress),
	}
}

func (n *Node) IsListening() bool {
	return n.isListening
}

// NodeInfo returns the Node's Info from the Switch.
func (n *Node) NodeInfo() p2p.NodeInfo {
	return n.nodeInfo
}

func makeNodeInfo(
	config *cfg.Config,
	nodeID p2p.ID,
	txIndexer txindex.TxIndexer,
	chainID string,
	protocolVersion p2p.ProtocolVersion,
) p2p.NodeInfo {
	txIndexerStatus := "on"
	if _, ok := txIndexer.(*null.TxIndex); ok {
		txIndexerStatus = "off"
	}
	nodeInfo := p2p.DefaultNodeInfo{
		ProtocolVersion: protocolVersion,
		ID_:             nodeID,
		Network:         chainID,
		Version:         version.TMCoreSemVer,
		Channels: []byte{
			bc.BlockchainChannel,
			cs.StateChannel, cs.DataChannel, cs.VoteChannel, cs.VoteSetBitsChannel,
			mempl.MempoolChannel,
			evidence.EvidenceChannel,
		},
		Moniker: config.Moniker,
		Other: p2p.DefaultNodeInfoOther{
			TxIndex:    txIndexerStatus,
			RPCAddress: config.RPC.ListenAddress,
		},
	}

	if config.P2P.PexReactor {
		nodeInfo.Channels = append(nodeInfo.Channels, pex.PexChannel)
	}

	lAddr := config.P2P.ExternalAddress

	if lAddr == "" {
		lAddr = config.P2P.ListenAddress
	}

	nodeInfo.ListenAddr = lAddr

	return nodeInfo
}

//------------------------------------------------------------------------------

var (
	genesisDocKey = []byte("genesisDoc")
)

// panics if failed to unmarshal bytes
func loadGenesisDoc(db dbm.DB) (*types.GenesisDoc, error) {
	bytes := db.Get(genesisDocKey)
	if len(bytes) == 0 {
		return nil, errors.New("Genesis doc not found")
	}
	var genDoc *types.GenesisDoc
	err := cdc.UnmarshalJSON(bytes, &genDoc)
	if err != nil {
		cmn.PanicCrisis(fmt.Sprintf("Failed to load genesis doc due to unmarshaling error: %v (bytes: %X)", err, bytes))
	}
	return genDoc, nil
}

// panics if failed to marshal the given genesis document
func saveGenesisDoc(db dbm.DB, genDoc *types.GenesisDoc) {
	bytes, err := cdc.MarshalJSON(genDoc)
	if err != nil {
		cmn.PanicCrisis(fmt.Sprintf("Failed to save genesis doc due to marshaling error: %v", err))
	}
	db.SetSync(genesisDocKey, bytes)
}

// splitAndTrimEmpty slices s into all subslices separated by sep and returns a
// slice of the string s with all leading and trailing Unicode code points
// contained in cutset removed. If sep is empty, SplitAndTrim splits after each
// UTF-8 sequence. First part is equivalent to strings.SplitN with a count of
// -1.  also filter out empty strings, only return non-empty strings.
func splitAndTrimEmpty(s, sep, cutset string) []string {
	if s == "" {
		return []string{}
	}

	spl := strings.Split(s, sep)
	nonEmptyStrings := make([]string, 0, len(spl))
	for i := 0; i < len(spl); i++ {
		element := strings.Trim(spl[i], cutset)
		if element != "" {
			nonEmptyStrings = append(nonEmptyStrings, element)
		}
	}
	return nonEmptyStrings
}