package lnd import ( "encoding/hex" "fmt" "io/ioutil" "net" "os" "path/filepath" "strconv" "strings" "sync" "time" "github.com/btcsuite/btcd/chaincfg/chainhash" "github.com/btcsuite/btcd/rpcclient" "github.com/btcsuite/btcutil" "github.com/btcsuite/btcwallet/chain" "github.com/btcsuite/btcwallet/wallet" "github.com/btcsuite/btcwallet/walletdb" "github.com/lightninglabs/neutrino" "github.com/lightninglabs/neutrino/headerfs" "github.com/lightningnetwork/lnd/chainntnfs" "github.com/lightningnetwork/lnd/chainntnfs/bitcoindnotify" "github.com/lightningnetwork/lnd/chainntnfs/btcdnotify" "github.com/lightningnetwork/lnd/chainntnfs/neutrinonotify" "github.com/lightningnetwork/lnd/channeldb" "github.com/lightningnetwork/lnd/htlcswitch" "github.com/lightningnetwork/lnd/input" "github.com/lightningnetwork/lnd/keychain" "github.com/lightningnetwork/lnd/lncfg" "github.com/lightningnetwork/lnd/lnwallet" "github.com/lightningnetwork/lnd/lnwallet/btcwallet" "github.com/lightningnetwork/lnd/lnwallet/chainfee" "github.com/lightningnetwork/lnd/lnwire" "github.com/lightningnetwork/lnd/routing/chainview" ) const ( // defaultBitcoinMinHTLCMSat is the default smallest value htlc this // node will accept. This value is proposed in the channel open sequence // and cannot be changed during the life of the channel. It is 1 msat by // default to allow maximum flexibility in deciding what size payments // to forward. // // All forwarded payments are subjected to the min htlc constraint of // the routing policy of the outgoing channel. This implicitly controls // the minimum htlc value on the incoming channel too. defaultBitcoinMinHTLCInMSat = lnwire.MilliSatoshi(1) // defaultBitcoinMinHTLCOutMSat is the default minimum htlc value that // we require for sending out htlcs. Our channel peer may have a lower // min htlc channel parameter, but we - by default - don't forward // anything under the value defined here. defaultBitcoinMinHTLCOutMSat = lnwire.MilliSatoshi(1000) // DefaultBitcoinBaseFeeMSat is the default forwarding base fee. DefaultBitcoinBaseFeeMSat = lnwire.MilliSatoshi(1000) // DefaultBitcoinFeeRate is the default forwarding fee rate. DefaultBitcoinFeeRate = lnwire.MilliSatoshi(1) // DefaultBitcoinTimeLockDelta is the default forwarding time lock // delta. DefaultBitcoinTimeLockDelta = 40 defaultLitecoinMinHTLCInMSat = lnwire.MilliSatoshi(1) defaultLitecoinMinHTLCOutMSat = lnwire.MilliSatoshi(1000) defaultLitecoinBaseFeeMSat = lnwire.MilliSatoshi(1000) defaultLitecoinFeeRate = lnwire.MilliSatoshi(1) defaultLitecoinTimeLockDelta = 576 defaultLitecoinDustLimit = btcutil.Amount(54600) // defaultBitcoinStaticFeePerKW is the fee rate of 50 sat/vbyte // expressed in sat/kw. defaultBitcoinStaticFeePerKW = chainfee.SatPerKWeight(12500) // defaultBitcoinStaticMinRelayFeeRate is the min relay fee used for // static estimators. defaultBitcoinStaticMinRelayFeeRate = chainfee.FeePerKwFloor // defaultLitecoinStaticFeePerKW is the fee rate of 200 sat/vbyte // expressed in sat/kw. defaultLitecoinStaticFeePerKW = chainfee.SatPerKWeight(50000) // btcToLtcConversionRate is a fixed ratio used in order to scale up // payments when running on the Litecoin chain. btcToLtcConversionRate = 60 ) // defaultBtcChannelConstraints is the default set of channel constraints that are // meant to be used when initially funding a Bitcoin channel. // // TODO(halseth): make configurable at startup? var defaultBtcChannelConstraints = channeldb.ChannelConstraints{ DustLimit: lnwallet.DefaultDustLimit(), MaxAcceptedHtlcs: input.MaxHTLCNumber / 2, } // defaultLtcChannelConstraints is the default set of channel constraints that are // meant to be used when initially funding a Litecoin channel. var defaultLtcChannelConstraints = channeldb.ChannelConstraints{ DustLimit: defaultLitecoinDustLimit, MaxAcceptedHtlcs: input.MaxHTLCNumber / 2, } // chainCode is an enum-like structure for keeping track of the chains // currently supported within lnd. type chainCode uint32 const ( // bitcoinChain is Bitcoin's testnet chain. bitcoinChain chainCode = iota // litecoinChain is Litecoin's testnet chain. litecoinChain ) // String returns a string representation of the target chainCode. func (c chainCode) String() string { switch c { case bitcoinChain: return "bitcoin" case litecoinChain: return "litecoin" default: return "kekcoin" } } // chainControl couples the three primary interfaces lnd utilizes for a // particular chain together. A single chainControl instance will exist for all // the chains lnd is currently active on. type chainControl struct { chainIO lnwallet.BlockChainIO feeEstimator chainfee.Estimator signer input.Signer keyRing keychain.SecretKeyRing wc lnwallet.WalletController msgSigner lnwallet.MessageSigner chainNotifier chainntnfs.ChainNotifier chainView chainview.FilteredChainView wallet *lnwallet.LightningWallet routingPolicy htlcswitch.ForwardingPolicy minHtlcIn lnwire.MilliSatoshi } // newChainControlFromConfig attempts to create a chainControl instance // according to the parameters in the passed lnd configuration. Currently three // branches of chainControl instances exist: one backed by a running btcd // full-node, another backed by a running bitcoind full-node, and the other // backed by a running neutrino light client instance. When running with a // neutrino light client instance, `neutrinoCS` must be non-nil. func newChainControlFromConfig(cfg *Config, chanDB *channeldb.DB, privateWalletPw, publicWalletPw []byte, birthday time.Time, recoveryWindow uint32, wallet *wallet.Wallet, neutrinoCS *neutrino.ChainService) (*chainControl, error) { // Set the RPC config from the "home" chain. Multi-chain isn't yet // active, so we'll restrict usage to a particular chain for now. homeChainConfig := cfg.Bitcoin if registeredChains.PrimaryChain() == litecoinChain { homeChainConfig = cfg.Litecoin } ltndLog.Infof("Primary chain is set to: %v", registeredChains.PrimaryChain()) cc := &chainControl{} switch registeredChains.PrimaryChain() { case bitcoinChain: cc.routingPolicy = htlcswitch.ForwardingPolicy{ MinHTLCOut: cfg.Bitcoin.MinHTLCOut, BaseFee: cfg.Bitcoin.BaseFee, FeeRate: cfg.Bitcoin.FeeRate, TimeLockDelta: cfg.Bitcoin.TimeLockDelta, } cc.minHtlcIn = cfg.Bitcoin.MinHTLCIn cc.feeEstimator = chainfee.NewStaticEstimator( defaultBitcoinStaticFeePerKW, defaultBitcoinStaticMinRelayFeeRate, ) case litecoinChain: cc.routingPolicy = htlcswitch.ForwardingPolicy{ MinHTLCOut: cfg.Litecoin.MinHTLCOut, BaseFee: cfg.Litecoin.BaseFee, FeeRate: cfg.Litecoin.FeeRate, TimeLockDelta: cfg.Litecoin.TimeLockDelta, } cc.minHtlcIn = cfg.Litecoin.MinHTLCIn cc.feeEstimator = chainfee.NewStaticEstimator( defaultLitecoinStaticFeePerKW, 0, ) default: return nil, fmt.Errorf("default routing policy for chain %v is "+ "unknown", registeredChains.PrimaryChain()) } walletConfig := &btcwallet.Config{ PrivatePass: privateWalletPw, PublicPass: publicWalletPw, Birthday: birthday, RecoveryWindow: recoveryWindow, DataDir: homeChainConfig.ChainDir, NetParams: activeNetParams.Params, CoinType: activeNetParams.CoinType, Wallet: wallet, } var err error // Initialize the height hint cache within the chain directory. hintCache, err := chainntnfs.NewHeightHintCache(chanDB) if err != nil { return nil, fmt.Errorf("unable to initialize height hint "+ "cache: %v", err) } // If spv mode is active, then we'll be using a distinct set of // chainControl interfaces that interface directly with the p2p network // of the selected chain. switch homeChainConfig.Node { case "neutrino": // We'll create ChainNotifier and FilteredChainView instances, // along with the wallet's ChainSource, which are all backed by // the neutrino light client. cc.chainNotifier = neutrinonotify.New( neutrinoCS, hintCache, hintCache, ) cc.chainView, err = chainview.NewCfFilteredChainView(neutrinoCS) if err != nil { return nil, err } // If the user provided an API for fee estimation, activate it now. if cfg.NeutrinoMode.FeeURL != "" { ltndLog.Infof("Using API fee estimator!") estimator := chainfee.NewWebAPIEstimator( chainfee.SparseConfFeeSource{ URL: cfg.NeutrinoMode.FeeURL, }, defaultBitcoinStaticFeePerKW, ) if err := estimator.Start(); err != nil { return nil, err } cc.feeEstimator = estimator } walletConfig.ChainSource = chain.NewNeutrinoClient( activeNetParams.Params, neutrinoCS, ) case "bitcoind", "litecoind": var bitcoindMode *lncfg.Bitcoind switch { case cfg.Bitcoin.Active: bitcoindMode = cfg.BitcoindMode case cfg.Litecoin.Active: bitcoindMode = cfg.LitecoindMode } // Otherwise, we'll be speaking directly via RPC and ZMQ to a // bitcoind node. If the specified host for the btcd/ltcd RPC // server already has a port specified, then we use that // directly. Otherwise, we assume the default port according to // the selected chain parameters. var bitcoindHost string if strings.Contains(bitcoindMode.RPCHost, ":") { bitcoindHost = bitcoindMode.RPCHost } else { // The RPC ports specified in chainparams.go assume // btcd, which picks a different port so that btcwallet // can use the same RPC port as bitcoind. We convert // this back to the btcwallet/bitcoind port. rpcPort, err := strconv.Atoi(activeNetParams.rpcPort) if err != nil { return nil, err } rpcPort -= 2 bitcoindHost = fmt.Sprintf("%v:%d", bitcoindMode.RPCHost, rpcPort) if (cfg.Bitcoin.Active && cfg.Bitcoin.RegTest) || (cfg.Litecoin.Active && cfg.Litecoin.RegTest) { conn, err := net.Dial("tcp", bitcoindHost) if err != nil || conn == nil { if cfg.Bitcoin.Active && cfg.Bitcoin.RegTest { rpcPort = 18443 } else if cfg.Litecoin.Active && cfg.Litecoin.RegTest { rpcPort = 19443 } bitcoindHost = fmt.Sprintf("%v:%d", bitcoindMode.RPCHost, rpcPort) } else { conn.Close() } } } // Establish the connection to bitcoind and create the clients // required for our relevant subsystems. bitcoindConn, err := chain.NewBitcoindConn( activeNetParams.Params, bitcoindHost, bitcoindMode.RPCUser, bitcoindMode.RPCPass, bitcoindMode.ZMQPubRawBlock, bitcoindMode.ZMQPubRawTx, 5*time.Second, ) if err != nil { return nil, err } if err := bitcoindConn.Start(); err != nil { return nil, fmt.Errorf("unable to connect to bitcoind: "+ "%v", err) } cc.chainNotifier = bitcoindnotify.New( bitcoindConn, activeNetParams.Params, hintCache, hintCache, ) cc.chainView = chainview.NewBitcoindFilteredChainView(bitcoindConn) walletConfig.ChainSource = bitcoindConn.NewBitcoindClient() // If we're not in regtest mode, then we'll attempt to use a // proper fee estimator for testnet. rpcConfig := &rpcclient.ConnConfig{ Host: bitcoindHost, User: bitcoindMode.RPCUser, Pass: bitcoindMode.RPCPass, DisableConnectOnNew: true, DisableAutoReconnect: false, DisableTLS: true, HTTPPostMode: true, } if cfg.Bitcoin.Active && !cfg.Bitcoin.RegTest { ltndLog.Infof("Initializing bitcoind backed fee estimator in "+ "%s mode", bitcoindMode.EstimateMode) // Finally, we'll re-initialize the fee estimator, as // if we're using bitcoind as a backend, then we can // use live fee estimates, rather than a statically // coded value. fallBackFeeRate := chainfee.SatPerKVByte(25 * 1000) cc.feeEstimator, err = chainfee.NewBitcoindEstimator( *rpcConfig, bitcoindMode.EstimateMode, fallBackFeeRate.FeePerKWeight(), ) if err != nil { return nil, err } if err := cc.feeEstimator.Start(); err != nil { return nil, err } } else if cfg.Litecoin.Active && !cfg.Litecoin.RegTest { ltndLog.Infof("Initializing litecoind backed fee estimator in "+ "%s mode", bitcoindMode.EstimateMode) // Finally, we'll re-initialize the fee estimator, as // if we're using litecoind as a backend, then we can // use live fee estimates, rather than a statically // coded value. fallBackFeeRate := chainfee.SatPerKVByte(25 * 1000) cc.feeEstimator, err = chainfee.NewBitcoindEstimator( *rpcConfig, bitcoindMode.EstimateMode, fallBackFeeRate.FeePerKWeight(), ) if err != nil { return nil, err } if err := cc.feeEstimator.Start(); err != nil { return nil, err } } case "btcd", "ltcd": // Otherwise, we'll be speaking directly via RPC to a node. // // So first we'll load btcd/ltcd's TLS cert for the RPC // connection. If a raw cert was specified in the config, then // we'll set that directly. Otherwise, we attempt to read the // cert from the path specified in the config. var btcdMode *lncfg.Btcd switch { case cfg.Bitcoin.Active: btcdMode = cfg.BtcdMode case cfg.Litecoin.Active: btcdMode = cfg.LtcdMode } var rpcCert []byte if btcdMode.RawRPCCert != "" { rpcCert, err = hex.DecodeString(btcdMode.RawRPCCert) if err != nil { return nil, err } } else { certFile, err := os.Open(btcdMode.RPCCert) if err != nil { return nil, err } rpcCert, err = ioutil.ReadAll(certFile) if err != nil { return nil, err } if err := certFile.Close(); err != nil { return nil, err } } // If the specified host for the btcd/ltcd RPC server already // has a port specified, then we use that directly. Otherwise, // we assume the default port according to the selected chain // parameters. var btcdHost string if strings.Contains(btcdMode.RPCHost, ":") { btcdHost = btcdMode.RPCHost } else { btcdHost = fmt.Sprintf("%v:%v", btcdMode.RPCHost, activeNetParams.rpcPort) } btcdUser := btcdMode.RPCUser btcdPass := btcdMode.RPCPass rpcConfig := &rpcclient.ConnConfig{ Host: btcdHost, Endpoint: "ws", User: btcdUser, Pass: btcdPass, Certificates: rpcCert, DisableTLS: false, DisableConnectOnNew: true, DisableAutoReconnect: false, } cc.chainNotifier, err = btcdnotify.New( rpcConfig, activeNetParams.Params, hintCache, hintCache, ) if err != nil { return nil, err } // Finally, we'll create an instance of the default chain view to be // used within the routing layer. cc.chainView, err = chainview.NewBtcdFilteredChainView(*rpcConfig) if err != nil { srvrLog.Errorf("unable to create chain view: %v", err) return nil, err } // Create a special websockets rpc client for btcd which will be used // by the wallet for notifications, calls, etc. chainRPC, err := chain.NewRPCClient(activeNetParams.Params, btcdHost, btcdUser, btcdPass, rpcCert, false, 20) if err != nil { return nil, err } walletConfig.ChainSource = chainRPC // If we're not in simnet or regtest mode, then we'll attempt // to use a proper fee estimator for testnet. if !cfg.Bitcoin.SimNet && !cfg.Litecoin.SimNet && !cfg.Bitcoin.RegTest && !cfg.Litecoin.RegTest { ltndLog.Infof("Initializing btcd backed fee estimator") // Finally, we'll re-initialize the fee estimator, as // if we're using btcd as a backend, then we can use // live fee estimates, rather than a statically coded // value. fallBackFeeRate := chainfee.SatPerKVByte(25 * 1000) cc.feeEstimator, err = chainfee.NewBtcdEstimator( *rpcConfig, fallBackFeeRate.FeePerKWeight(), ) if err != nil { return nil, err } if err := cc.feeEstimator.Start(); err != nil { return nil, err } } default: return nil, fmt.Errorf("unknown node type: %s", homeChainConfig.Node) } wc, err := btcwallet.New(*walletConfig) if err != nil { fmt.Printf("unable to create wallet controller: %v\n", err) return nil, err } cc.msgSigner = wc cc.signer = wc cc.chainIO = wc cc.wc = wc // Select the default channel constraints for the primary chain. channelConstraints := defaultBtcChannelConstraints if registeredChains.PrimaryChain() == litecoinChain { channelConstraints = defaultLtcChannelConstraints } keyRing := keychain.NewBtcWalletKeyRing( wc.InternalWallet(), activeNetParams.CoinType, ) cc.keyRing = keyRing // Create, and start the lnwallet, which handles the core payment // channel logic, and exposes control via proxy state machines. walletCfg := lnwallet.Config{ Database: chanDB, Notifier: cc.chainNotifier, WalletController: wc, Signer: cc.signer, FeeEstimator: cc.feeEstimator, SecretKeyRing: keyRing, ChainIO: cc.chainIO, DefaultConstraints: channelConstraints, NetParams: *activeNetParams.Params, } lnWallet, err := lnwallet.NewLightningWallet(walletCfg) if err != nil { fmt.Printf("unable to create wallet: %v\n", err) return nil, err } if err := lnWallet.Startup(); err != nil { fmt.Printf("unable to start wallet: %v\n", err) return nil, err } ltndLog.Info("LightningWallet opened") cc.wallet = lnWallet return cc, nil } var ( // bitcoinTestnetGenesis is the genesis hash of Bitcoin's testnet // chain. bitcoinTestnetGenesis = chainhash.Hash([chainhash.HashSize]byte{ 0x43, 0x49, 0x7f, 0xd7, 0xf8, 0x26, 0x95, 0x71, 0x08, 0xf4, 0xa3, 0x0f, 0xd9, 0xce, 0xc3, 0xae, 0xba, 0x79, 0x97, 0x20, 0x84, 0xe9, 0x0e, 0xad, 0x01, 0xea, 0x33, 0x09, 0x00, 0x00, 0x00, 0x00, }) // bitcoinMainnetGenesis is the genesis hash of Bitcoin's main chain. bitcoinMainnetGenesis = chainhash.Hash([chainhash.HashSize]byte{ 0x6f, 0xe2, 0x8c, 0x0a, 0xb6, 0xf1, 0xb3, 0x72, 0xc1, 0xa6, 0xa2, 0x46, 0xae, 0x63, 0xf7, 0x4f, 0x93, 0x1e, 0x83, 0x65, 0xe1, 0x5a, 0x08, 0x9c, 0x68, 0xd6, 0x19, 0x00, 0x00, 0x00, 0x00, 0x00, }) // litecoinTestnetGenesis is the genesis hash of Litecoin's testnet4 // chain. litecoinTestnetGenesis = chainhash.Hash([chainhash.HashSize]byte{ 0xa0, 0x29, 0x3e, 0x4e, 0xeb, 0x3d, 0xa6, 0xe6, 0xf5, 0x6f, 0x81, 0xed, 0x59, 0x5f, 0x57, 0x88, 0x0d, 0x1a, 0x21, 0x56, 0x9e, 0x13, 0xee, 0xfd, 0xd9, 0x51, 0x28, 0x4b, 0x5a, 0x62, 0x66, 0x49, }) // litecoinMainnetGenesis is the genesis hash of Litecoin's main chain. litecoinMainnetGenesis = chainhash.Hash([chainhash.HashSize]byte{ 0xe2, 0xbf, 0x04, 0x7e, 0x7e, 0x5a, 0x19, 0x1a, 0xa4, 0xef, 0x34, 0xd3, 0x14, 0x97, 0x9d, 0xc9, 0x98, 0x6e, 0x0f, 0x19, 0x25, 0x1e, 0xda, 0xba, 0x59, 0x40, 0xfd, 0x1f, 0xe3, 0x65, 0xa7, 0x12, }) // chainMap is a simple index that maps a chain's genesis hash to the // chainCode enum for that chain. chainMap = map[chainhash.Hash]chainCode{ bitcoinTestnetGenesis: bitcoinChain, litecoinTestnetGenesis: litecoinChain, bitcoinMainnetGenesis: bitcoinChain, litecoinMainnetGenesis: litecoinChain, } // chainDNSSeeds is a map of a chain's hash to the set of DNS seeds // that will be use to bootstrap peers upon first startup. // // The first item in the array is the primary host we'll use to attempt // the SRV lookup we require. If we're unable to receive a response // over UDP, then we'll fall back to manual TCP resolution. The second // item in the array is a special A record that we'll query in order to // receive the IP address of the current authoritative DNS server for // the network seed. // // TODO(roasbeef): extend and collapse these and chainparams.go into // struct like chaincfg.Params chainDNSSeeds = map[chainhash.Hash][][2]string{ bitcoinMainnetGenesis: { { "nodes.lightning.directory", "soa.nodes.lightning.directory", }, { "lseed.bitcoinstats.com", }, }, bitcoinTestnetGenesis: { { "test.nodes.lightning.directory", "soa.nodes.lightning.directory", }, }, litecoinMainnetGenesis: { { "ltc.nodes.lightning.directory", "soa.nodes.lightning.directory", }, }, } ) // chainRegistry keeps track of the current chains type chainRegistry struct { sync.RWMutex activeChains map[chainCode]*chainControl netParams map[chainCode]*bitcoinNetParams primaryChain chainCode } // newChainRegistry creates a new chainRegistry. func newChainRegistry() *chainRegistry { return &chainRegistry{ activeChains: make(map[chainCode]*chainControl), netParams: make(map[chainCode]*bitcoinNetParams), } } // RegisterChain assigns an active chainControl instance to a target chain // identified by its chainCode. func (c *chainRegistry) RegisterChain(newChain chainCode, cc *chainControl) { c.Lock() c.activeChains[newChain] = cc c.Unlock() } // LookupChain attempts to lookup an active chainControl instance for the // target chain. func (c *chainRegistry) LookupChain(targetChain chainCode) (*chainControl, bool) { c.RLock() cc, ok := c.activeChains[targetChain] c.RUnlock() return cc, ok } // LookupChainByHash attempts to look up an active chainControl which // corresponds to the passed genesis hash. func (c *chainRegistry) LookupChainByHash(chainHash chainhash.Hash) (*chainControl, bool) { c.RLock() defer c.RUnlock() targetChain, ok := chainMap[chainHash] if !ok { return nil, ok } cc, ok := c.activeChains[targetChain] return cc, ok } // RegisterPrimaryChain sets a target chain as the "home chain" for lnd. func (c *chainRegistry) RegisterPrimaryChain(cc chainCode) { c.Lock() defer c.Unlock() c.primaryChain = cc } // PrimaryChain returns the primary chain for this running lnd instance. The // primary chain is considered the "home base" while the other registered // chains are treated as secondary chains. func (c *chainRegistry) PrimaryChain() chainCode { c.RLock() defer c.RUnlock() return c.primaryChain } // ActiveChains returns a slice containing the active chains. func (c *chainRegistry) ActiveChains() []chainCode { c.RLock() defer c.RUnlock() chains := make([]chainCode, 0, len(c.activeChains)) for activeChain := range c.activeChains { chains = append(chains, activeChain) } return chains } // NumActiveChains returns the total number of active chains. func (c *chainRegistry) NumActiveChains() uint32 { c.RLock() defer c.RUnlock() return uint32(len(c.activeChains)) } // initNeutrinoBackend inits a new instance of the neutrino light client // backend given a target chain directory to store the chain state. func initNeutrinoBackend(chainDir string) (*neutrino.ChainService, func(), error) { // First we'll open the database file for neutrino, creating the // database if needed. We append the normalized network name here to // match the behavior of btcwallet. dbPath := filepath.Join( chainDir, normalizeNetwork(activeNetParams.Name), ) // Ensure that the neutrino db path exists. if err := os.MkdirAll(dbPath, 0700); err != nil { return nil, nil, err } dbName := filepath.Join(dbPath, "neutrino.db") db, err := walletdb.Create("bdb", dbName, !cfg.SyncFreelist) if err != nil { return nil, nil, fmt.Errorf("unable to create neutrino "+ "database: %v", err) } headerStateAssertion, err := parseHeaderStateAssertion( cfg.NeutrinoMode.AssertFilterHeader, ) if err != nil { db.Close() return nil, nil, err } // With the database open, we can now create an instance of the // neutrino light client. We pass in relevant configuration parameters // required. config := neutrino.Config{ DataDir: dbPath, Database: db, ChainParams: *activeNetParams.Params, AddPeers: cfg.NeutrinoMode.AddPeers, ConnectPeers: cfg.NeutrinoMode.ConnectPeers, Dialer: func(addr net.Addr) (net.Conn, error) { return cfg.net.Dial(addr.Network(), addr.String()) }, NameResolver: func(host string) ([]net.IP, error) { addrs, err := cfg.net.LookupHost(host) if err != nil { return nil, err } ips := make([]net.IP, 0, len(addrs)) for _, strIP := range addrs { ip := net.ParseIP(strIP) if ip == nil { continue } ips = append(ips, ip) } return ips, nil }, AssertFilterHeader: headerStateAssertion, } neutrino.MaxPeers = 8 neutrino.BanDuration = time.Hour * 48 neutrinoCS, err := neutrino.NewChainService(config) if err != nil { db.Close() return nil, nil, fmt.Errorf("unable to create neutrino light "+ "client: %v", err) } if err := neutrinoCS.Start(); err != nil { db.Close() return nil, nil, err } cleanUp := func() { neutrinoCS.Stop() db.Close() } return neutrinoCS, cleanUp, nil } // parseHeaderStateAssertion parses the user-specified neutrino header state // into a headerfs.FilterHeader. func parseHeaderStateAssertion(state string) (*headerfs.FilterHeader, error) { if len(state) == 0 { return nil, nil } split := strings.Split(state, ":") if len(split) != 2 { return nil, fmt.Errorf("header state assertion %v in "+ "unexpected format, expected format height:hash", state) } height, err := strconv.ParseUint(split[0], 10, 32) if err != nil { return nil, fmt.Errorf("invalid filter header height: %v", err) } hash, err := chainhash.NewHashFromStr(split[1]) if err != nil { return nil, fmt.Errorf("invalid filter header hash: %v", err) } return &headerfs.FilterHeader{ Height: uint32(height), FilterHash: *hash, }, nil }