tendermint/node/node.go

package node

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"net"
	"net/http"
	_ "net/http/pprof" // nolint: gosec // securely exposed on separate, optional port
	"strings"
	"time"

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

	dbm "github.com/tendermint/tm-db"

	abci "github.com/tendermint/tendermint/abci/types"
	bcv0 "github.com/tendermint/tendermint/blockchain/v0"
	bcv1 "github.com/tendermint/tendermint/blockchain/v1"
	bcv2 "github.com/tendermint/tendermint/blockchain/v2"
	cfg "github.com/tendermint/tendermint/config"
	cs "github.com/tendermint/tendermint/consensus"
	"github.com/tendermint/tendermint/crypto"
	"github.com/tendermint/tendermint/evidence"
	tmjson "github.com/tendermint/tendermint/libs/json"
	"github.com/tendermint/tendermint/libs/log"
	tmpubsub "github.com/tendermint/tendermint/libs/pubsub"
	"github.com/tendermint/tendermint/libs/service"
	"github.com/tendermint/tendermint/light"
	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"
	grpccore "github.com/tendermint/tendermint/rpc/grpc"
	rpcserver "github.com/tendermint/tendermint/rpc/jsonrpc/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/statesync"
	"github.com/tendermint/tendermint/store"
	"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.BackendType(ctx.Config.DBBackend)
	return dbm.NewDB(ctx.ID, dbType, ctx.Config.DBDir())
}

// 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())
	}
}

// Provider takes a config and a logger and returns a ready to go Node.
type Provider 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) {
	nodeKey, err := p2p.LoadOrGenNodeKey(config.NodeKeyFile())
	if err != nil {
		return nil, fmt.Errorf("failed to load or gen node key %s: %w", config.NodeKeyFile(), err)
	}

	pval, err := privval.LoadOrGenFilePV(config.PrivValidatorKeyFile(), config.PrivValidatorStateFile())
	if err != nil {
		return nil, err
	}

	return NewNode(config,
		pval,
		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(chainID string) (*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(chainID string) (*cs.Metrics, *p2p.Metrics, *mempl.Metrics, *sm.Metrics) {
		if config.Prometheus {
			return cs.PrometheusMetrics(config.Namespace, "chain_id", chainID),
				p2p.PrometheusMetrics(config.Namespace, "chain_id", chainID),
				mempl.PrometheusMetrics(config.Namespace, "chain_id", chainID),
				sm.PrometheusMetrics(config.Namespace, "chain_id", chainID)
		}
		return cs.NopMetrics(), p2p.NopMetrics(), mempl.NopMetrics(), sm.NopMetrics()
	}
}

// Option sets a parameter for the node.
type Option func(*Node)

// Temporary interface for switching to fast sync, we should get rid of v0 and v1 reactors.
// See: https://github.com/tendermint/tendermint/issues/4595
type fastSyncReactor interface {
	SwitchToFastSync(sm.State) error
}

// CustomReactors allows you to add custom reactors (name -> p2p.Reactor) to
// the node's Switch.
//
// WARNING: using any name from the below list of the existing reactors will
// result in replacing it with the custom one.
//
//  - MEMPOOL
//  - BLOCKCHAIN
//  - CONSENSUS
//  - EVIDENCE
//  - PEX
//  - STATESYNC
func CustomReactors(reactors map[string]p2p.Reactor) Option {
	return func(n *Node) {
		for name, reactor := range reactors {
			if existingReactor := n.sw.Reactor(name); existingReactor != nil {
				n.sw.Logger.Info("Replacing existing reactor with a custom one",
					"name", name, "existing", existingReactor, "custom", reactor)
				n.sw.RemoveReactor(name, existingReactor)
			}
			n.sw.AddReactor(name, reactor)
		}
	}
}

// StateProvider overrides the state provider used by state sync to retrieve trusted app hashes and
// build a State object for bootstrapping the node.
// WARNING: this interface is considered unstable and subject to change.
func StateProvider(stateProvider statesync.StateProvider) Option {
	return func(n *Node) {
		n.stateSyncProvider = stateProvider
	}
}

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

// Node is the highest level interface to a full Tendermint node.
// It includes all configuration information and running services.
type Node struct {
	service.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
	stateStore        sm.Store
	blockStore        *store.BlockStore // store the blockchain to disk
	bcReactor         p2p.Reactor       // for fast-syncing
	mempoolReactor    *mempl.Reactor    // for gossipping transactions
	mempool           mempl.Mempool
	stateSync         bool                    // whether the node should state sync on startup
	stateSyncReactor  *statesync.Reactor      // for hosting and restoring state sync snapshots
	stateSyncProvider statesync.StateProvider // provides state data for bootstrapping a node
	stateSyncGenesis  sm.State                // provides the genesis state for state sync
	consensusState    *cs.State               // latest consensus state
	consensusReactor  *cs.Reactor             // for participating in the consensus
	pexReactor        *pex.Reactor            // for exchanging peer addresses
	evidencePool      *evidence.Pool          // tracking evidence
	proxyApp          proxy.AppConns          // connection to the application
	rpcListeners      []net.Listener          // rpc servers
	txIndexer         txindex.TxIndexer
	indexerService    *txindex.IndexerService
	prometheusSrv     *http.Server
}

func initDBs(config *cfg.Config, dbProvider DBProvider) (blockStore *store.BlockStore, stateDB dbm.DB, err error) {
	var blockStoreDB dbm.DB
	blockStoreDB, err = dbProvider(&DBContext{"blockstore", config})
	if err != nil {
		return
	}
	blockStore = store.NewBlockStore(blockStoreDB)

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

	return
}

func createAndStartProxyAppConns(clientCreator proxy.ClientCreator, logger log.Logger) (proxy.AppConns, error) {
	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)
	}
	return proxyApp, nil
}

func createAndStartEventBus(logger log.Logger) (*types.EventBus, error) {
	eventBus := types.NewEventBus()
	eventBus.SetLogger(logger.With("module", "events"))
	if err := eventBus.Start(); err != nil {
		return nil, err
	}
	return eventBus, nil
}

func createAndStartIndexerService(config *cfg.Config, dbProvider DBProvider,
	eventBus *types.EventBus, logger log.Logger) (*txindex.IndexerService, txindex.TxIndexer, error) {

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

	indexerService := txindex.NewIndexerService(txIndexer, eventBus)
	indexerService.SetLogger(logger.With("module", "txindex"))
	if err := indexerService.Start(); err != nil {
		return nil, nil, err
	}
	return indexerService, txIndexer, nil
}

func doHandshake(
	stateStore sm.Store,
	state sm.State,
	blockStore sm.BlockStore,
	genDoc *types.GenesisDoc,
	eventBus types.BlockEventPublisher,
	proxyApp proxy.AppConns,
	consensusLogger log.Logger) error {

	handshaker := cs.NewHandshaker(stateStore, state, blockStore, genDoc)
	handshaker.SetLogger(consensusLogger)
	handshaker.SetEventBus(eventBus)
	if err := handshaker.Handshake(proxyApp); err != nil {
		return fmt.Errorf("error during handshake: %v", err)
	}
	return nil
}

func logNodeStartupInfo(state sm.State, pubKey crypto.PubKey, logger, consensusLogger log.Logger) {
	// Log the version info.
	logger.Info("Version info",
		"software", version.TMCoreSemVer,
		"block", version.BlockProtocol,
		"p2p", version.P2PProtocol,
	)

	// If the state and software differ in block version, at least log it.
	if state.Version.Consensus.Block != version.BlockProtocol {
		logger.Info("Software and state have different block protocols",
			"software", version.BlockProtocol,
			"state", state.Version.Consensus.Block,
		)
	}

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

func onlyValidatorIsUs(state sm.State, pubKey crypto.PubKey) bool {
	if state.Validators.Size() > 1 {
		return false
	}
	addr, _ := state.Validators.GetByIndex(0)
	return bytes.Equal(pubKey.Address(), addr)
}

func createMempoolAndMempoolReactor(config *cfg.Config, proxyApp proxy.AppConns,
	state sm.State, memplMetrics *mempl.Metrics, logger log.Logger) (*mempl.Reactor, *mempl.CListMempool) {

	mempool := mempl.NewCListMempool(
		config.Mempool,
		proxyApp.Mempool(),
		state.LastBlockHeight,
		mempl.WithMetrics(memplMetrics),
		mempl.WithPreCheck(sm.TxPreCheck(state)),
		mempl.WithPostCheck(sm.TxPostCheck(state)),
	)
	mempoolLogger := logger.With("module", "mempool")
	mempoolReactor := mempl.NewReactor(config.Mempool, mempool)
	mempoolReactor.SetLogger(mempoolLogger)

	if config.Consensus.WaitForTxs() {
		mempool.EnableTxsAvailable()
	}
	return mempoolReactor, mempool
}

func createEvidenceReactor(config *cfg.Config, dbProvider DBProvider,
	stateDB dbm.DB, blockStore *store.BlockStore, logger log.Logger) (*evidence.Reactor, *evidence.Pool, error) {

	evidenceDB, err := dbProvider(&DBContext{"evidence", config})
	if err != nil {
		return nil, nil, err
	}
	evidenceLogger := logger.With("module", "evidence")
	evidencePool, err := evidence.NewPool(evidenceDB, sm.NewStore(stateDB), blockStore)
	if err != nil {
		return nil, nil, err
	}
	evidenceReactor := evidence.NewReactor(evidencePool)
	evidenceReactor.SetLogger(evidenceLogger)
	return evidenceReactor, evidencePool, nil
}

func createBlockchainReactor(config *cfg.Config,
	state sm.State,
	blockExec *sm.BlockExecutor,
	blockStore *store.BlockStore,
	fastSync bool,
	logger log.Logger) (bcReactor p2p.Reactor, err error) {

	switch config.FastSync.Version {
	case "v0":
		bcReactor = bcv0.NewBlockchainReactor(state.Copy(), blockExec, blockStore, fastSync)
	case "v1":
		bcReactor = bcv1.NewBlockchainReactor(state.Copy(), blockExec, blockStore, fastSync)
	case "v2":
		bcReactor = bcv2.NewBlockchainReactor(state.Copy(), blockExec, blockStore, fastSync)
	default:
		return nil, fmt.Errorf("unknown fastsync version %s", config.FastSync.Version)
	}

	bcReactor.SetLogger(logger.With("module", "blockchain"))
	return bcReactor, nil
}

func createConsensusReactor(config *cfg.Config,
	state sm.State,
	blockExec *sm.BlockExecutor,
	blockStore sm.BlockStore,
	mempool *mempl.CListMempool,
	evidencePool *evidence.Pool,
	privValidator types.PrivValidator,
	csMetrics *cs.Metrics,
	waitSync bool,
	eventBus *types.EventBus,
	consensusLogger log.Logger) (*cs.Reactor, *cs.State) {

	consensusState := cs.NewState(
		config.Consensus,
		state.Copy(),
		blockExec,
		blockStore,
		mempool,
		evidencePool,
		cs.StateMetrics(csMetrics),
	)
	consensusState.SetLogger(consensusLogger)
	if privValidator != nil {
		consensusState.SetPrivValidator(privValidator)
	}
	consensusReactor := cs.NewReactor(consensusState, waitSync, cs.ReactorMetrics(csMetrics))
	consensusReactor.SetLogger(consensusLogger)
	// services which will be publishing and/or subscribing for messages (events)
	// consensusReactor will set it on consensusState and blockExecutor
	consensusReactor.SetEventBus(eventBus)
	return consensusReactor, consensusState
}

func createTransport(
	config *cfg.Config,
	nodeInfo p2p.NodeInfo,
	nodeKey *p2p.NodeKey,
	proxyApp proxy.AppConns,
) (
	*p2p.MultiplexTransport,
	[]p2p.PeerFilterFunc,
) {
	var (
		mConnConfig = p2p.MConnConfig(config.P2P)
		transport   = p2p.NewMultiplexTransport(nodeInfo, *nodeKey, mConnConfig)
		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)

	// Limit the number of incoming connections.
	max := config.P2P.MaxNumInboundPeers + len(splitAndTrimEmpty(config.P2P.UnconditionalPeerIDs, ",", " "))
	p2p.MultiplexTransportMaxIncomingConnections(max)(transport)

	return transport, peerFilters
}

func createSwitch(config *cfg.Config,
	transport p2p.Transport,
	p2pMetrics *p2p.Metrics,
	peerFilters []p2p.PeerFilterFunc,
	mempoolReactor *mempl.Reactor,
	bcReactor p2p.Reactor,
	stateSyncReactor *statesync.Reactor,
	consensusReactor *cs.Reactor,
	evidenceReactor *evidence.Reactor,
	nodeInfo p2p.NodeInfo,
	nodeKey *p2p.NodeKey,
	p2pLogger log.Logger) *p2p.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.AddReactor("STATESYNC", stateSyncReactor)

	sw.SetNodeInfo(nodeInfo)
	sw.SetNodeKey(nodeKey)

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

func createAddrBookAndSetOnSwitch(config *cfg.Config, sw *p2p.Switch,
	p2pLogger log.Logger, nodeKey *p2p.NodeKey) (pex.AddrBook, error) {

	addrBook := pex.NewAddrBook(config.P2P.AddrBookFile(), config.P2P.AddrBookStrict)
	addrBook.SetLogger(p2pLogger.With("book", config.P2P.AddrBookFile()))

	// Add ourselves to addrbook to prevent dialing ourselves
	if config.P2P.ExternalAddress != "" {
		addr, err := p2p.NewNetAddressString(p2p.IDAddressString(nodeKey.ID(), config.P2P.ExternalAddress))
		if err != nil {
			return nil, fmt.Errorf("p2p.external_address is incorrect: %w", err)
		}
		addrBook.AddOurAddress(addr)
	}
	if config.P2P.ListenAddress != "" {
		addr, err := p2p.NewNetAddressString(p2p.IDAddressString(nodeKey.ID(), config.P2P.ListenAddress))
		if err != nil {
			return nil, fmt.Errorf("p2p.laddr is incorrect: %w", err)
		}
		addrBook.AddOurAddress(addr)
	}

	sw.SetAddrBook(addrBook)

	return addrBook, nil
}

func createPEXReactorAndAddToSwitch(addrBook pex.AddrBook, config *cfg.Config,
	sw *p2p.Switch, logger log.Logger) *pex.Reactor {

	// TODO persistent peers ? so we can have their DNS addrs saved
	pexReactor := pex.NewReactor(addrBook,
		&pex.ReactorConfig{
			Seeds:    splitAndTrimEmpty(config.P2P.Seeds, ",", " "),
			SeedMode: config.P2P.SeedMode,
			// See consensus/reactor.go: blocksToContributeToBecomeGoodPeer 10000
			// blocks assuming 10s blocks ~ 28 hours.
			// TODO (melekes): make it dynamic based on the actual block latencies
			// from the live network.
			// https://github.com/tendermint/tendermint/issues/3523
			SeedDisconnectWaitPeriod:     28 * time.Hour,
			PersistentPeersMaxDialPeriod: config.P2P.PersistentPeersMaxDialPeriod,
		})
	pexReactor.SetLogger(logger.With("module", "pex"))
	sw.AddReactor("PEX", pexReactor)
	return pexReactor
}

// startStateSync starts an asynchronous state sync process, then switches to fast sync mode.
func startStateSync(ssR *statesync.Reactor, bcR fastSyncReactor, conR *cs.Reactor,
	stateProvider statesync.StateProvider, config *cfg.StateSyncConfig, fastSync bool,
	stateStore sm.Store, blockStore *store.BlockStore, state sm.State) error {
	ssR.Logger.Info("Starting state sync")

	if stateProvider == nil {
		var err error
		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
		defer cancel()
		stateProvider, err = statesync.NewLightClientStateProvider(
			ctx,
			state.ChainID, state.Version, state.InitialHeight,
			config.RPCServers, light.TrustOptions{
				Period: config.TrustPeriod,
				Height: config.TrustHeight,
				Hash:   config.TrustHashBytes(),
			}, ssR.Logger.With("module", "light"))
		if err != nil {
			return fmt.Errorf("failed to set up light client state provider: %w", err)
		}
	}

	go func() {
		state, commit, err := ssR.Sync(stateProvider, config.DiscoveryTime)
		if err != nil {
			ssR.Logger.Error("State sync failed", "err", err)
			return
		}
		err = stateStore.Bootstrap(state)
		if err != nil {
			ssR.Logger.Error("Failed to bootstrap node with new state", "err", err)
			return
		}
		err = blockStore.SaveSeenCommit(state.LastBlockHeight, commit)
		if err != nil {
			ssR.Logger.Error("Failed to store last seen commit", "err", err)
			return
		}

		if fastSync {
			// FIXME Very ugly to have these metrics bleed through here.
			conR.Metrics.StateSyncing.Set(0)
			conR.Metrics.FastSyncing.Set(1)
			err = bcR.SwitchToFastSync(state)
			if err != nil {
				ssR.Logger.Error("Failed to switch to fast sync", "err", err)
				return
			}
		} else {
			conR.SwitchToConsensus(state, true)
		}
	}()
	return nil
}

// 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,
	options ...Option) (*Node, error) {

	blockStore, stateDB, err := initDBs(config, dbProvider)
	if err != nil {
		return nil, err
	}

	stateStore := sm.NewStore(stateDB)

	state, genDoc, err := LoadStateFromDBOrGenesisDocProvider(stateDB, genesisDocProvider)
	if err != nil {
		return nil, err
	}

	// Create the proxyApp and establish connections to the ABCI app (consensus, mempool, query).
	proxyApp, err := createAndStartProxyAppConns(clientCreator, logger)
	if err != nil {
		return nil, err
	}

	// EventBus and IndexerService must be started before the handshake because
	// we might need to index the txs of the replayed block as this might not have happened
	// when the node stopped last time (i.e. the node stopped after it saved the block
	// but before it indexed the txs, or, endblocker panicked)
	eventBus, err := createAndStartEventBus(logger)
	if err != nil {
		return nil, err
	}

	// Transaction indexing
	indexerService, txIndexer, err := createAndStartIndexerService(config, dbProvider, eventBus, logger)
	if err != nil {
		return nil, err
	}

	// If an address is provided, listen on the socket for a connection from an
	// external signing process.
	if config.PrivValidatorListenAddr != "" {
		// FIXME: we should start services inside OnStart
		privValidator, err = createAndStartPrivValidatorSocketClient(config.PrivValidatorListenAddr, genDoc.ChainID, logger)
		if err != nil {
			return nil, fmt.Errorf("error with private validator socket client: %w", err)
		}
	}

	pubKey, err := privValidator.GetPubKey()
	if err != nil {
		return nil, fmt.Errorf("can't get pubkey: %w", err)
	}

	// Determine whether we should attempt state sync.
	stateSync := config.StateSync.Enable && !onlyValidatorIsUs(state, pubKey)
	if stateSync && state.LastBlockHeight > 0 {
		logger.Info("Found local state with non-zero height, skipping state sync")
		stateSync = false
	}

	// 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")
	if !stateSync {
		if err := doHandshake(stateStore, state, blockStore, genDoc, eventBus, proxyApp, consensusLogger); err != nil {
			return nil, 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, err = stateStore.Load()
		if err != nil {
			return nil, fmt.Errorf("cannot load state: %w", err)
		}
	}

	// Determine whether we should do fast sync. This must happen after the handshake, since the
	// app may modify the validator set, specifying ourself as the only validator.
	fastSync := config.FastSyncMode && !onlyValidatorIsUs(state, pubKey)

	logNodeStartupInfo(state, pubKey, logger, consensusLogger)

	csMetrics, p2pMetrics, memplMetrics, smMetrics := metricsProvider(genDoc.ChainID)

	// Make MempoolReactor
	mempoolReactor, mempool := createMempoolAndMempoolReactor(config, proxyApp, state, memplMetrics, logger)

	// Make Evidence Reactor
	evidenceReactor, evidencePool, err := createEvidenceReactor(config, dbProvider, stateDB, blockStore, logger)
	if err != nil {
		return nil, err
	}

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

	// Make BlockchainReactor. Don't start fast sync if we're doing a state sync first.
	bcReactor, err := createBlockchainReactor(config, state, blockExec, blockStore, fastSync && !stateSync, logger)
	if err != nil {
		return nil, fmt.Errorf("could not create blockchain reactor: %w", err)
	}

	// Make ConsensusReactor. Don't enable fully if doing a state sync and/or fast sync first.
	// FIXME We need to update metrics here, since other reactors don't have access to them.
	if stateSync {
		csMetrics.StateSyncing.Set(1)
	} else if fastSync {
		csMetrics.FastSyncing.Set(1)
	}
	consensusReactor, consensusState := createConsensusReactor(
		config, state, blockExec, blockStore, mempool, evidencePool,
		privValidator, csMetrics, stateSync || fastSync, eventBus, consensusLogger,
	)

	// Set up state sync reactor, and schedule a sync if requested.
	// FIXME The way we do phased startups (e.g. replay -> fast sync -> consensus) is very messy,
	// we should clean this whole thing up. See:
	// https://github.com/tendermint/tendermint/issues/4644
	stateSyncReactor := statesync.NewReactor(proxyApp.Snapshot(), proxyApp.Query(),
		config.StateSync.TempDir)
	stateSyncReactor.SetLogger(logger.With("module", "statesync"))

	nodeInfo, err := makeNodeInfo(config, nodeKey, txIndexer, genDoc, state)
	if err != nil {
		return nil, err
	}

	// Setup Transport.
	transport, peerFilters := createTransport(config, nodeInfo, nodeKey, proxyApp)

	// Setup Switch.
	p2pLogger := logger.With("module", "p2p")
	sw := createSwitch(
		config, transport, p2pMetrics, peerFilters, mempoolReactor, bcReactor,
		stateSyncReactor, consensusReactor, evidenceReactor, nodeInfo, nodeKey, p2pLogger,
	)

	err = sw.AddPersistentPeers(splitAndTrimEmpty(config.P2P.PersistentPeers, ",", " "))
	if err != nil {
		return nil, fmt.Errorf("could not add peers from persistent_peers field: %w", err)
	}

	err = sw.AddUnconditionalPeerIDs(splitAndTrimEmpty(config.P2P.UnconditionalPeerIDs, ",", " "))
	if err != nil {
		return nil, fmt.Errorf("could not add peer ids from unconditional_peer_ids field: %w", err)
	}

	addrBook, err := createAddrBookAndSetOnSwitch(config, sw, p2pLogger, nodeKey)
	if err != nil {
		return nil, fmt.Errorf("could not create addrbook: %w", err)
	}

	// 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
	var pexReactor *pex.Reactor
	if config.P2P.PexReactor {
		pexReactor = createPEXReactorAndAddToSwitch(addrBook, config, sw, logger)
	}

	if config.RPC.PprofListenAddress != "" {
		go func() {
			logger.Info("Starting pprof server", "laddr", config.RPC.PprofListenAddress)
			logger.Error("pprof server error", "err", http.ListenAndServe(config.RPC.PprofListenAddress, nil))
		}()
	}

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

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

		stateStore:       stateStore,
		blockStore:       blockStore,
		bcReactor:        bcReactor,
		mempoolReactor:   mempoolReactor,
		mempool:          mempool,
		consensusState:   consensusState,
		consensusReactor: consensusReactor,
		stateSyncReactor: stateSyncReactor,
		stateSync:        stateSync,
		stateSyncGenesis: state, // Shouldn't be necessary, but need a way to pass the genesis state
		pexReactor:       pexReactor,
		evidencePool:     evidencePool,
		proxyApp:         proxyApp,
		txIndexer:        txIndexer,
		indexerService:   indexerService,
		eventBus:         eventBus,
	}
	node.BaseService = *service.NewBaseService(logger, "Node", node)

	for _, option := range options {
		option(node)
	}

	return node, nil
}

// OnStart starts the Node. It implements service.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))
	}

	// 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.NewNetAddressString(p2p.IDAddressString(n.nodeKey.ID(), n.config.P2P.ListenAddress))
	if err != nil {
		return err
	}
	if err := n.transport.Listen(*addr); err != nil {
		return err
	}

	n.isListening = true

	if n.config.Mempool.WalEnabled() {
		err = n.mempool.InitWAL()
		if err != nil {
			return fmt.Errorf("init mempool WAL: %w", err)
		}
	}

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

	// Always connect to persistent peers
	err = n.sw.DialPeersAsync(splitAndTrimEmpty(n.config.P2P.PersistentPeers, ",", " "))
	if err != nil {
		return fmt.Errorf("could not dial peers from persistent_peers field: %w", err)
	}

	// Run state sync
	if n.stateSync {
		bcR, ok := n.bcReactor.(fastSyncReactor)
		if !ok {
			return fmt.Errorf("this blockchain reactor does not support switching from state sync")
		}
		err := startStateSync(n.stateSyncReactor, bcR, n.consensusReactor, n.stateSyncProvider,
			n.config.StateSync, n.config.FastSyncMode, n.stateStore, n.blockStore, n.stateSyncGenesis)
		if err != nil {
			return fmt.Errorf("failed to start state sync: %w", err)
		}
	}

	return nil
}

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

	n.Logger.Info("Stopping Node")

	// first stop the non-reactor services
	if err := n.eventBus.Stop(); err != nil {
		n.Logger.Error("Error closing eventBus", "err", err)
	}
	if err := n.indexerService.Stop(); err != nil {
		n.Logger.Error("Error closing indexerService", "err", err)
	}

	// now stop the reactors
	if err := n.sw.Stop(); err != nil {
		n.Logger.Error("Error closing switch", "err", err)
	}

	// stop mempool WAL
	if n.config.Mempool.WalEnabled() {
		n.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.(service.Service); ok {
		if err := pvsc.Stop(); err != nil {
			n.Logger.Error("Error closing private validator", "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 makes sure RPC has all the objects it needs to operate.
func (n *Node) ConfigureRPC() error {
	pubKey, err := n.privValidator.GetPubKey()
	if err != nil {
		return fmt.Errorf("can't get pubkey: %w", err)
	}
	rpccore.SetEnvironment(&rpccore.Environment{
		ProxyAppQuery:   n.proxyApp.Query(),
		ProxyAppMempool: n.proxyApp.Mempool(),

		StateStore:     n.stateStore,
		BlockStore:     n.blockStore,
		EvidencePool:   n.evidencePool,
		ConsensusState: n.consensusState,
		P2PPeers:       n.sw,
		P2PTransport:   n,

		PubKey:           pubKey,
		GenDoc:           n.genesisDoc,
		TxIndexer:        n.txIndexer,
		ConsensusReactor: n.consensusReactor,
		EventBus:         n.eventBus,
		Mempool:          n.mempool,

		Logger: n.Logger.With("module", "rpc"),

		Config: *n.config.RPC,
	})
	return nil
}

func (n *Node) startRPC() ([]net.Listener, error) {
	err := n.ConfigureRPC()
	if err != nil {
		return nil, err
	}

	listenAddrs := splitAndTrimEmpty(n.config.RPC.ListenAddress, ",", " ")

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

	config := rpcserver.DefaultConfig()
	config.MaxBodyBytes = n.config.RPC.MaxBodyBytes
	config.MaxHeaderBytes = n.config.RPC.MaxHeaderBytes
	config.MaxOpenConnections = n.config.RPC.MaxOpenConnections
	// If necessary adjust global WriteTimeout to ensure it's greater than
	// TimeoutBroadcastTxCommit.
	// See https://github.com/tendermint/tendermint/issues/3435
	if config.WriteTimeout <= n.config.RPC.TimeoutBroadcastTxCommit {
		config.WriteTimeout = n.config.RPC.TimeoutBroadcastTxCommit + 1*time.Second
	}

	// 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")
		wmLogger := rpcLogger.With("protocol", "websocket")
		wm := rpcserver.NewWebsocketManager(rpccore.Routes,
			rpcserver.OnDisconnect(func(remoteAddr string) {
				err := n.eventBus.UnsubscribeAll(context.Background(), remoteAddr)
				if err != nil && err != tmpubsub.ErrSubscriptionNotFound {
					wmLogger.Error("Failed to unsubscribe addr from events", "addr", remoteAddr, "err", err)
				}
			}),
			rpcserver.ReadLimit(config.MaxBodyBytes),
		)
		wm.SetLogger(wmLogger)
		mux.HandleFunc("/websocket", wm.WebsocketHandler)
		rpcserver.RegisterRPCFuncs(mux, rpccore.Routes, rpcLogger)
		listener, err := rpcserver.Listen(
			listenAddr,
			config,
		)
		if err != nil {
			return nil, err
		}

		var rootHandler http.Handler = mux
		if n.config.RPC.IsCorsEnabled() {
			corsMiddleware := cors.New(cors.Options{
				AllowedOrigins: n.config.RPC.CORSAllowedOrigins,
				AllowedMethods: n.config.RPC.CORSAllowedMethods,
				AllowedHeaders: n.config.RPC.CORSAllowedHeaders,
			})
			rootHandler = corsMiddleware.Handler(mux)
		}
		if n.config.RPC.IsTLSEnabled() {
			go func() {
				if err := rpcserver.ServeTLS(
					listener,
					rootHandler,
					n.config.RPC.CertFile(),
					n.config.RPC.KeyFile(),
					rpcLogger,
					config,
				); err != nil {
					n.Logger.Error("Error serving server with TLS", "err", err)
				}
			}()
		} else {
			go func() {
				if err := rpcserver.Serve(
					listener,
					rootHandler,
					rpcLogger,
					config,
				); err != nil {
					n.Logger.Error("Error serving server", "err", err)
				}
			}()
		}

		listeners[i] = listener
	}

	// we expose a simplified api over grpc for convenience to app devs
	grpcListenAddr := n.config.RPC.GRPCListenAddress
	if grpcListenAddr != "" {
		config := rpcserver.DefaultConfig()
		config.MaxBodyBytes = n.config.RPC.MaxBodyBytes
		config.MaxHeaderBytes = n.config.RPC.MaxHeaderBytes
		// NOTE: GRPCMaxOpenConnections is used, not MaxOpenConnections
		config.MaxOpenConnections = n.config.RPC.GRPCMaxOpenConnections
		// If necessary adjust global WriteTimeout to ensure it's greater than
		// TimeoutBroadcastTxCommit.
		// See https://github.com/tendermint/tendermint/issues/3435
		if config.WriteTimeout <= n.config.RPC.TimeoutBroadcastTxCommit {
			config.WriteTimeout = n.config.RPC.TimeoutBroadcastTxCommit + 1*time.Second
		}
		listener, err := rpcserver.Listen(grpcListenAddr, config)
		if err != nil {
			return nil, err
		}
		go func() {
			if err := grpccore.StartGRPCServer(listener); err != nil {
				n.Logger.Error("Error starting gRPC server", "err", 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() *store.BlockStore {
	return n.blockStore
}

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

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

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

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

// PEXReactor returns the Node's PEXReactor. It returns nil if PEX is disabled.
func (n *Node) PEXReactor() *pex.Reactor {
	return n.pexReactor
}

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

// Config returns the Node's config.
func (n *Node) Config() *cfg.Config {
	return n.config
}

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

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,
	nodeKey *p2p.NodeKey,
	txIndexer txindex.TxIndexer,
	genDoc *types.GenesisDoc,
	state sm.State,
) (p2p.NodeInfo, error) {
	txIndexerStatus := "on"
	if _, ok := txIndexer.(*null.TxIndex); ok {
		txIndexerStatus = "off"
	}

	var bcChannel byte
	switch config.FastSync.Version {
	case "v0":
		bcChannel = bcv0.BlockchainChannel
	case "v1":
		bcChannel = bcv1.BlockchainChannel
	case "v2":
		bcChannel = bcv2.BlockchainChannel
	default:
		return nil, fmt.Errorf("unknown fastsync version %s", config.FastSync.Version)
	}

	nodeInfo := p2p.DefaultNodeInfo{
		ProtocolVersion: p2p.NewProtocolVersion(
			version.P2PProtocol, // global
			state.Version.Consensus.Block,
			state.Version.Consensus.App,
		),
		DefaultNodeID: nodeKey.ID(),
		Network:       genDoc.ChainID,
		Version:       version.TMCoreSemVer,
		Channels: []byte{
			bcChannel,
			cs.StateChannel, cs.DataChannel, cs.VoteChannel, cs.VoteSetBitsChannel,
			mempl.MempoolChannel,
			evidence.EvidenceChannel,
			statesync.SnapshotChannel, statesync.ChunkChannel,
		},
		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

	err := nodeInfo.Validate()
	return nodeInfo, err
}

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

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

// LoadStateFromDBOrGenesisDocProvider attempts to load the state from the
// database, or creates one using the given genesisDocProvider. On success this also
// returns the genesis doc loaded through the given provider.
func LoadStateFromDBOrGenesisDocProvider(
	stateDB dbm.DB,
	genesisDocProvider GenesisDocProvider,
) (sm.State, *types.GenesisDoc, error) {
	// Get genesis doc
	genDoc, err := loadGenesisDoc(stateDB)
	if err != nil {
		genDoc, err = genesisDocProvider()
		if err != nil {
			return sm.State{}, 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.
		if err := saveGenesisDoc(stateDB, genDoc); err != nil {
			return sm.State{}, nil, err
		}
	}
	stateStore := sm.NewStore(stateDB)
	state, err := stateStore.LoadFromDBOrGenesisDoc(genDoc)
	if err != nil {
		return sm.State{}, nil, err
	}
	return state, genDoc, nil
}

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

// panics if failed to marshal the given genesis document
func saveGenesisDoc(db dbm.DB, genDoc *types.GenesisDoc) error {
	b, err := tmjson.Marshal(genDoc)
	if err != nil {
		return fmt.Errorf("failed to save genesis doc due to marshaling error: %w", err)
	}
	if err := db.SetSync(genesisDocKey, b); err != nil {
		return err
	}

	return nil
}

func createAndStartPrivValidatorSocketClient(
	listenAddr,
	chainID string,
	logger log.Logger,
) (types.PrivValidator, error) {
	pve, err := privval.NewSignerListener(listenAddr, logger)
	if err != nil {
		return nil, fmt.Errorf("failed to start private validator: %w", err)
	}

	pvsc, err := privval.NewSignerClient(pve, chainID)
	if err != nil {
		return nil, fmt.Errorf("failed to start private validator: %w", err)
	}

	// try to get a pubkey from private validate first time
	_, err = pvsc.GetPubKey()
	if err != nil {
		return nil, fmt.Errorf("can't get pubkey: %w", err)
	}

	const (
		retries = 50 // 50 * 100ms = 5s total
		timeout = 100 * time.Millisecond
	)
	pvscWithRetries := privval.NewRetrySignerClient(pvsc, retries, timeout)

	return pvscWithRetries, nil
}

// 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
}