lnd.xprv/lnd.go
2018-02-06 19:11:11 -08:00

815 lines
23 KiB
Go

// Copyright (c) 2013-2017 The btcsuite developers
// Copyright (c) 2015-2016 The Decred developers
// Copyright (C) 2015-2017 The Lightning Network Developers
package main
import (
"bytes"
"crypto/rand"
"crypto/rsa"
"crypto/tls"
"crypto/x509"
"crypto/x509/pkix"
"encoding/pem"
"fmt"
"io/ioutil"
"math/big"
"net"
"net/http"
_ "net/http/pprof"
"os"
"path/filepath"
"runtime"
"runtime/pprof"
"sync"
"time"
"gopkg.in/macaroon-bakery.v2/bakery"
"golang.org/x/net/context"
"google.golang.org/grpc"
"google.golang.org/grpc/credentials"
proxy "github.com/grpc-ecosystem/grpc-gateway/runtime"
flags "github.com/jessevdk/go-flags"
"github.com/lightningnetwork/lnd/autopilot"
"github.com/lightningnetwork/lnd/channeldb"
"github.com/lightningnetwork/lnd/lnrpc"
"github.com/lightningnetwork/lnd/lnwallet"
"github.com/lightningnetwork/lnd/lnwire"
"github.com/lightningnetwork/lnd/macaroons"
"github.com/lightningnetwork/lnd/walletunlocker"
"github.com/roasbeef/btcd/btcec"
"github.com/roasbeef/btcd/wire"
"github.com/roasbeef/btcutil"
)
const (
// Make certificate valid for 14 months.
autogenCertValidity = 14 /*months*/ * 30 /*days*/ * 24 * time.Hour
)
var (
cfg *config
shutdownChannel = make(chan struct{})
registeredChains = newChainRegistry()
macaroonDatabaseDir string
// End of ASN.1 time.
endOfTime = time.Date(2049, 12, 31, 23, 59, 59, 0, time.UTC)
// Max serial number.
serialNumberLimit = new(big.Int).Lsh(big.NewInt(1), 128)
/*
* These cipher suites fit the following criteria:
* - Don't use outdated algorithms like SHA-1 and 3DES
* - Don't use ECB mode or other insecure symmetric methods
* - Included in the TLS v1.2 suite
* - Are available in the Go 1.7.6 standard library (more are
* available in 1.8.3 and will be added after lnd no longer
* supports 1.7, including suites that support CBC mode)
*
* The cipher suites are ordered from strongest to weakest
* primitives, but the client's preference order has more
* effect during negotiation.
**/
tlsCipherSuites = []uint16{
tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
tls.TLS_RSA_WITH_AES_256_GCM_SHA384,
tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256,
tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256,
tls.TLS_RSA_WITH_AES_128_CBC_SHA256,
tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
tls.TLS_RSA_WITH_AES_128_GCM_SHA256,
tls.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305,
tls.TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305,
}
)
// lndMain is the true entry point for lnd. This function is required since
// defers created in the top-level scope of a main method aren't executed if
// os.Exit() is called.
func lndMain() error {
// Load the configuration, and parse any command line options. This
// function will also set up logging properly.
loadedConfig, err := loadConfig()
if err != nil {
return err
}
cfg = loadedConfig
defer func() {
if logRotator != nil {
logRotator.Close()
}
}()
// Show version at startup.
ltndLog.Infof("Version %s", version())
// Enable http profiling server if requested.
if cfg.Profile != "" {
go func() {
listenAddr := net.JoinHostPort("", cfg.Profile)
profileRedirect := http.RedirectHandler("/debug/pprof",
http.StatusSeeOther)
http.Handle("/", profileRedirect)
fmt.Println(http.ListenAndServe(listenAddr, nil))
}()
}
// Write cpu profile if requested.
if cfg.CPUProfile != "" {
f, err := os.Create(cfg.CPUProfile)
if err != nil {
ltndLog.Errorf("Unable to create cpu profile: %v", err)
return err
}
pprof.StartCPUProfile(f)
defer f.Close()
defer pprof.StopCPUProfile()
}
// Create the network-segmented directory for the channel database.
graphDir := filepath.Join(cfg.DataDir,
defaultGraphSubDirname,
normalizeNetwork(activeNetParams.Name))
// Open the channeldb, which is dedicated to storing channel, and
// network related metadata.
chanDB, err := channeldb.Open(graphDir)
if err != nil {
ltndLog.Errorf("unable to open channeldb: %v", err)
return err
}
defer chanDB.Close()
// Only process macaroons if --no-macaroons isn't set.
ctx := context.Background()
ctx, cancel := context.WithCancel(ctx)
defer cancel()
// Ensure we create TLS key and certificate if they don't exist
if !fileExists(cfg.TLSCertPath) && !fileExists(cfg.TLSKeyPath) {
if err := genCertPair(cfg.TLSCertPath, cfg.TLSKeyPath); err != nil {
return err
}
}
cert, err := tls.LoadX509KeyPair(cfg.TLSCertPath, cfg.TLSKeyPath)
if err != nil {
return err
}
tlsConf := &tls.Config{
Certificates: []tls.Certificate{cert},
CipherSuites: tlsCipherSuites,
MinVersion: tls.VersionTLS12,
}
sCreds := credentials.NewTLS(tlsConf)
serverOpts := []grpc.ServerOption{grpc.Creds(sCreds)}
cCreds, err := credentials.NewClientTLSFromFile(cfg.TLSCertPath, "")
if err != nil {
return err
}
proxyOpts := []grpc.DialOption{grpc.WithTransportCredentials(cCreds)}
var macaroonService *macaroons.Service
if !cfg.NoMacaroons {
// Create the macaroon authentication/authorization service.
macaroonService, err = macaroons.NewService(macaroonDatabaseDir,
macaroons.IPLockChecker)
if err != nil {
srvrLog.Errorf("unable to create macaroon service: %v", err)
return err
}
defer macaroonService.Close()
}
// We wait until the user provides a password over RPC. In case lnd is
// started with the --noencryptwallet flag, we use the default password
// "hello" for wallet encryption.
privateWalletPw := []byte("hello")
publicWalletPw := []byte("public")
if !cfg.NoEncryptWallet {
privateWalletPw, publicWalletPw, err = waitForWalletPassword(
cfg.RPCListeners, cfg.RESTListeners, serverOpts, proxyOpts,
tlsConf, macaroonService,
)
if err != nil {
return err
}
}
if !cfg.NoMacaroons {
// Try to unlock the macaroon store with the private password.
// Ignore ErrAlreadyUnlocked since it could be unlocked by the
// wallet unlocker.
err = macaroonService.CreateUnlock(&privateWalletPw)
if err != nil && err != macaroons.ErrAlreadyUnlocked {
srvrLog.Error(err)
return err
}
// Create macaroon files for lncli to use if they don't exist.
if !fileExists(cfg.AdminMacPath) && !fileExists(cfg.ReadMacPath) {
err = genMacaroons(ctx, macaroonService,
cfg.AdminMacPath, cfg.ReadMacPath)
if err != nil {
ltndLog.Errorf("unable to create macaroon "+
"files: %v", err)
return err
}
}
}
// With the information parsed from the configuration, create valid
// instances of the pertinent interfaces required to operate the
// Lightning Network Daemon.
activeChainControl, chainCleanUp, err := newChainControlFromConfig(cfg,
chanDB, privateWalletPw, publicWalletPw)
if err != nil {
fmt.Printf("unable to create chain control: %v\n", err)
return err
}
if chainCleanUp != nil {
defer chainCleanUp()
}
// Finally before we start the server, we'll register the "holy
// trinity" of interface for our current "home chain" with the active
// chainRegistry interface.
primaryChain := registeredChains.PrimaryChain()
registeredChains.RegisterChain(primaryChain, activeChainControl)
idPrivKey, err := activeChainControl.wallet.GetIdentitykey()
if err != nil {
return err
}
idPrivKey.Curve = btcec.S256()
// Set up the core server which will listen for incoming peer
// connections.
server, err := newServer(cfg.Listeners, chanDB, activeChainControl,
idPrivKey)
if err != nil {
srvrLog.Errorf("unable to create server: %v\n", err)
return err
}
// Next, we'll initialize the funding manager itself so it can answer
// queries while the wallet+chain are still syncing.
nodeSigner := newNodeSigner(idPrivKey)
var chanIDSeed [32]byte
if _, err := rand.Read(chanIDSeed[:]); err != nil {
return err
}
fundingMgr, err := newFundingManager(fundingConfig{
IDKey: idPrivKey.PubKey(),
Wallet: activeChainControl.wallet,
Notifier: activeChainControl.chainNotifier,
FeeEstimator: activeChainControl.feeEstimator,
SignMessage: func(pubKey *btcec.PublicKey,
msg []byte) (*btcec.Signature, error) {
if pubKey.IsEqual(idPrivKey.PubKey()) {
return nodeSigner.SignMessage(pubKey, msg)
}
return activeChainControl.msgSigner.SignMessage(
pubKey, msg,
)
},
CurrentNodeAnnouncement: func() (lnwire.NodeAnnouncement, error) {
return server.genNodeAnnouncement(true)
},
SendAnnouncement: func(msg lnwire.Message) error {
errChan := server.authGossiper.ProcessLocalAnnouncement(msg,
idPrivKey.PubKey())
return <-errChan
},
ArbiterChan: server.breachArbiter.newContracts,
SendToPeer: server.SendToPeer,
NotifyWhenOnline: server.NotifyWhenOnline,
FindPeer: server.FindPeer,
TempChanIDSeed: chanIDSeed,
FindChannel: func(chanID lnwire.ChannelID) (*lnwallet.LightningChannel, error) {
dbChannels, err := chanDB.FetchAllChannels()
if err != nil {
return nil, err
}
for _, channel := range dbChannels {
if chanID.IsChanPoint(&channel.FundingOutpoint) {
// TODO(roasbeef): populate beacon
return lnwallet.NewLightningChannel(
activeChainControl.signer,
server.witnessBeacon,
channel)
}
}
return nil, fmt.Errorf("unable to find channel")
},
DefaultRoutingPolicy: activeChainControl.routingPolicy,
NumRequiredConfs: func(chanAmt btcutil.Amount,
pushAmt lnwire.MilliSatoshi) uint16 {
// For large channels we increase the number
// of confirmations we require for the
// channel to be considered open. As it is
// always the responder that gets to choose
// value, the pushAmt is value being pushed
// to us. This means we have more to lose
// in the case this gets re-orged out, and
// we will require more confirmations before
// we consider it open.
// TODO(halseth): Use Litecoin params in case
// of LTC channels.
// In case the user has explicitly specified
// a default value for the number of
// confirmations, we use it.
defaultConf := uint16(cfg.Bitcoin.DefaultNumChanConfs)
if defaultConf != 0 {
return defaultConf
}
// If not we return a value scaled linearly
// between 3 and 6, depending on channel size.
// TODO(halseth): Use 1 as minimum?
minConf := uint64(3)
maxConf := uint64(6)
maxChannelSize := uint64(
lnwire.NewMSatFromSatoshis(maxFundingAmount))
stake := lnwire.NewMSatFromSatoshis(chanAmt) + pushAmt
conf := maxConf * uint64(stake) / maxChannelSize
if conf < minConf {
conf = minConf
}
if conf > maxConf {
conf = maxConf
}
return uint16(conf)
},
RequiredRemoteDelay: func(chanAmt btcutil.Amount) uint16 {
// We scale the remote CSV delay (the time the
// remote have to claim funds in case of a unilateral
// close) linearly from minRemoteDelay blocks
// for small channels, to maxRemoteDelay blocks
// for channels of size maxFundingAmount.
// TODO(halseth): Litecoin parameter for LTC.
// In case the user has explicitly specified
// a default value for the remote delay, we
// use it.
defaultDelay := uint16(cfg.Bitcoin.DefaultRemoteDelay)
if defaultDelay > 0 {
return defaultDelay
}
// If not we scale according to channel size.
delay := uint16(maxRemoteDelay *
chanAmt / maxFundingAmount)
if delay < minRemoteDelay {
delay = minRemoteDelay
}
if delay > maxRemoteDelay {
delay = maxRemoteDelay
}
return delay
},
WatchNewChannel: server.chainArb.WatchNewChannel,
ReportShortChanID: func(chanPoint wire.OutPoint,
sid lnwire.ShortChannelID) error {
cid := lnwire.NewChanIDFromOutPoint(&chanPoint)
return server.htlcSwitch.UpdateShortChanID(cid, sid)
},
})
if err != nil {
return err
}
if err := fundingMgr.Start(); err != nil {
return err
}
server.fundingMgr = fundingMgr
// Check macaroon authentication if macaroons aren't disabled.
if macaroonService != nil {
serverOpts = append(serverOpts,
grpc.UnaryInterceptor(macaroonService.
UnaryServerInterceptor(permissions)),
grpc.StreamInterceptor(macaroonService.
StreamServerInterceptor(permissions)),
)
}
// Initialize, and register our implementation of the gRPC interface
// exported by the rpcServer.
rpcServer := newRPCServer(server)
if err := rpcServer.Start(); err != nil {
return err
}
grpcServer := grpc.NewServer(serverOpts...)
lnrpc.RegisterLightningServer(grpcServer, rpcServer)
// Next, Start the gRPC server listening for HTTP/2 connections.
for _, listener := range cfg.RPCListeners {
lis, err := net.Listen("tcp", listener)
if err != nil {
ltndLog.Errorf("RPC server unable to listen on %s", listener)
return err
}
defer lis.Close()
go func() {
rpcsLog.Infof("RPC server listening on %s", lis.Addr())
grpcServer.Serve(lis)
}()
}
// Finally, start the REST proxy for our gRPC server above.
mux := proxy.NewServeMux()
err = lnrpc.RegisterLightningHandlerFromEndpoint(ctx, mux,
cfg.RPCListeners[0], proxyOpts)
if err != nil {
return err
}
for _, restEndpoint := range cfg.RESTListeners {
listener, err := tls.Listen("tcp", restEndpoint, tlsConf)
if err != nil {
ltndLog.Errorf("gRPC proxy unable to listen on %s", restEndpoint)
return err
}
defer listener.Close()
go func() {
rpcsLog.Infof("gRPC proxy started at %s", listener.Addr())
http.Serve(listener, mux)
}()
}
// If we're not in simnet mode, We'll wait until we're fully synced to
// continue the start up of the remainder of the daemon. This ensures
// that we don't accept any possibly invalid state transitions, or
// accept channels with spent funds.
if !(cfg.Bitcoin.SimNet || cfg.Litecoin.SimNet) {
_, bestHeight, err := activeChainControl.chainIO.GetBestBlock()
if err != nil {
return err
}
ltndLog.Infof("Waiting for chain backend to finish sync, "+
"start_height=%v", bestHeight)
for {
synced, err := activeChainControl.wallet.IsSynced()
if err != nil {
return err
}
if synced {
break
}
time.Sleep(time.Second * 1)
}
_, bestHeight, err = activeChainControl.chainIO.GetBestBlock()
if err != nil {
return err
}
ltndLog.Infof("Chain backend is fully synced (end_height=%v)!",
bestHeight)
}
// With all the relevant chains initialized, we can finally start the
// server itself.
if err := server.Start(); err != nil {
srvrLog.Errorf("unable to start server: %v\n", err)
return err
}
// Now that the server has started, if the autopilot mode is currently
// active, then we'll initialize a fresh instance of it and start it.
var pilot *autopilot.Agent
if cfg.Autopilot.Active {
pilot, err := initAutoPilot(server, cfg.Autopilot)
if err != nil {
ltndLog.Errorf("unable to create autopilot agent: %v",
err)
return err
}
if err := pilot.Start(); err != nil {
ltndLog.Errorf("unable to start autopilot agent: %v",
err)
return err
}
}
addInterruptHandler(func() {
ltndLog.Infof("Gracefully shutting down the server...")
rpcServer.Stop()
fundingMgr.Stop()
server.Stop()
if pilot != nil {
pilot.Stop()
}
server.WaitForShutdown()
})
// Wait for shutdown signal from either a graceful server stop or from
// the interrupt handler.
<-shutdownChannel
ltndLog.Info("Shutdown complete")
return nil
}
func main() {
// Use all processor cores.
// TODO(roasbeef): remove this if required version # is > 1.6?
runtime.GOMAXPROCS(runtime.NumCPU())
// Call the "real" main in a nested manner so the defers will properly
// be executed in the case of a graceful shutdown.
if err := lndMain(); err != nil {
if e, ok := err.(*flags.Error); ok && e.Type == flags.ErrHelp {
} else {
fmt.Fprintln(os.Stderr, err)
}
os.Exit(1)
}
}
// fileExists reports whether the named file or directory exists.
// This function is taken from https://github.com/btcsuite/btcd
func fileExists(name string) bool {
if _, err := os.Stat(name); err != nil {
if os.IsNotExist(err) {
return false
}
}
return true
}
// genCertPair generates a key/cert pair to the paths provided. The
// auto-generated certificates should *not* be used in production for public
// access as they're self-signed and don't necessarily contain all of the
// desired hostnames for the service. For production/public use, consider a
// real PKI.
//
// This function is adapted from https://github.com/btcsuite/btcd and
// https://github.com/btcsuite/btcutil
func genCertPair(certFile, keyFile string) error {
rpcsLog.Infof("Generating TLS certificates...")
org := "lnd autogenerated cert"
now := time.Now()
validUntil := now.Add(autogenCertValidity)
// Check that the certificate validity isn't past the ASN.1 end of time.
if validUntil.After(endOfTime) {
validUntil = endOfTime
}
// Generate a serial number that's below the serialNumberLimit.
serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
if err != nil {
return fmt.Errorf("failed to generate serial number: %s", err)
}
// Collect the host's IP addresses, including loopback, in a slice.
ipAddresses := []net.IP{net.ParseIP("127.0.0.1"), net.ParseIP("::1")}
// addIP appends an IP address only if it isn't already in the slice.
addIP := func(ipAddr net.IP) {
for _, ip := range ipAddresses {
if bytes.Equal(ip, ipAddr) {
return
}
}
ipAddresses = append(ipAddresses, ipAddr)
}
// Add all the interface IPs that aren't already in the slice.
addrs, err := net.InterfaceAddrs()
if err != nil {
return err
}
for _, a := range addrs {
ipAddr, _, err := net.ParseCIDR(a.String())
if err == nil {
addIP(ipAddr)
}
}
// Collect the host's names into a slice.
host, err := os.Hostname()
if err != nil {
return err
}
dnsNames := []string{host}
if host != "localhost" {
dnsNames = append(dnsNames, "localhost")
}
// Generate a private key for the certificate.
priv, err := rsa.GenerateKey(rand.Reader, 4096)
if err != nil {
return err
}
// Construct the certificate template.
template := x509.Certificate{
SerialNumber: serialNumber,
Subject: pkix.Name{
Organization: []string{org},
CommonName: host,
},
NotBefore: now.Add(-time.Hour * 24),
NotAfter: validUntil,
KeyUsage: x509.KeyUsageKeyEncipherment |
x509.KeyUsageDigitalSignature | x509.KeyUsageCertSign,
IsCA: true, // so can sign self.
BasicConstraintsValid: true,
DNSNames: dnsNames,
IPAddresses: ipAddresses,
// This signature algorithm is most likely to be compatible
// with clients using less-common TLS libraries like BoringSSL.
SignatureAlgorithm: x509.SHA256WithRSA,
}
derBytes, err := x509.CreateCertificate(rand.Reader, &template,
&template, &priv.PublicKey, priv)
if err != nil {
return fmt.Errorf("failed to create certificate: %v", err)
}
certBuf := &bytes.Buffer{}
err = pem.Encode(certBuf, &pem.Block{Type: "CERTIFICATE",
Bytes: derBytes})
if err != nil {
return fmt.Errorf("failed to encode certificate: %v", err)
}
keybytes := x509.MarshalPKCS1PrivateKey(priv)
keyBuf := &bytes.Buffer{}
err = pem.Encode(keyBuf, &pem.Block{Type: "RSA PRIVATE KEY",
Bytes: keybytes})
if err != nil {
return fmt.Errorf("failed to encode private key: %v", err)
}
// Write cert and key files.
if err = ioutil.WriteFile(certFile, certBuf.Bytes(), 0644); err != nil {
return err
}
if err = ioutil.WriteFile(keyFile, keyBuf.Bytes(), 0600); err != nil {
os.Remove(certFile)
return err
}
rpcsLog.Infof("Done generating TLS certificates")
return nil
}
// genMacaroons generates a pair of macaroon files; one admin-level and one
// read-only. These can also be used to generate more granular macaroons.
func genMacaroons(ctx context.Context, svc *macaroons.Service, admFile,
roFile string) error {
// Generate the read-only macaroon and write it to a file.
roMacaroon, err := svc.Oven.NewMacaroon(ctx, bakery.LatestVersion, nil,
readPermissions...)
if err != nil {
return err
}
roBytes, err := roMacaroon.M().MarshalBinary()
if err != nil {
return err
}
if err = ioutil.WriteFile(roFile, roBytes, 0644); err != nil {
os.Remove(admFile)
return err
}
// Generate the admin macaroon and write it to a file.
admMacaroon, err := svc.Oven.NewMacaroon(ctx, bakery.LatestVersion,
nil, append(readPermissions, writePermissions...)...)
if err != nil {
return err
}
admBytes, err := admMacaroon.M().MarshalBinary()
if err != nil {
return err
}
if err = ioutil.WriteFile(admFile, admBytes, 0600); err != nil {
return err
}
return nil
}
// waitForWalletPassword will spin up gRPC and REST endpoints for the
// WalletUnlocker server, and block until a password is provided by
// the user to this RPC server.
func waitForWalletPassword(grpcEndpoints, restEndpoints []string,
serverOpts []grpc.ServerOption, proxyOpts []grpc.DialOption,
tlsConf *tls.Config, macaroonService *macaroons.Service) ([]byte, []byte, error) {
// Set up a new PasswordService, which will listen
// for passwords provided over RPC.
grpcServer := grpc.NewServer(serverOpts...)
chainConfig := cfg.Bitcoin
if registeredChains.PrimaryChain() == litecoinChain {
chainConfig = cfg.Litecoin
}
pwService := walletunlocker.New(macaroonService,
chainConfig.ChainDir, activeNetParams.Params)
lnrpc.RegisterWalletUnlockerServer(grpcServer, pwService)
// Use a WaitGroup so we can be sure the instructions on how to input the
// password is the last thing to be printed to the console.
var wg sync.WaitGroup
for _, grpcEndpoint := range grpcEndpoints {
// Start a gRPC server listening for HTTP/2 connections, solely
// used for getting the encryption password from the client.
lis, err := net.Listen("tcp", grpcEndpoint)
if err != nil {
ltndLog.Errorf("password RPC server unable to listen on %s",
grpcEndpoint)
return nil, nil, err
}
defer lis.Close()
wg.Add(1)
go func() {
rpcsLog.Infof("password RPC server listening on %s", lis.Addr())
wg.Done()
grpcServer.Serve(lis)
}()
}
// Start a REST proxy for our gRPC server above.
ctx := context.Background()
ctx, cancel := context.WithCancel(ctx)
defer cancel()
mux := proxy.NewServeMux()
err := lnrpc.RegisterWalletUnlockerHandlerFromEndpoint(ctx, mux,
grpcEndpoints[0], proxyOpts)
if err != nil {
return nil, nil, err
}
srv := &http.Server{Handler: mux}
for _, restEndpoint := range restEndpoints {
lis, err := tls.Listen("tcp", restEndpoint, tlsConf)
if err != nil {
ltndLog.Errorf("password gRPC proxy unable to listen on %s",
restEndpoint)
return nil, nil, err
}
defer lis.Close()
wg.Add(1)
go func() {
rpcsLog.Infof("password gRPC proxy started at %s", lis.Addr())
wg.Done()
srv.Serve(lis)
}()
}
// Wait for gRPC and REST servers to be up running.
wg.Wait()
// Wait for user to provide the password.
ltndLog.Infof("Waiting for wallet encryption password. " +
"Use `lncli create` to create wallet, or " +
"`lncli unlock` to unlock already created wallet.")
// We currently don't distinguish between getting a password to
// be used for creation or unlocking, as a new wallet db will be
// created if none exists when creating the chain control.
select {
case walletPw := <-pwService.CreatePasswords:
return walletPw, walletPw, nil
case walletPw := <-pwService.UnlockPasswords:
return walletPw, walletPw, nil
case <-shutdownChannel:
return nil, nil, fmt.Errorf("shutting down")
}
}