10182608679

Committed 31 Jul 2024 02:55PM UTC coverage: 58.459% (-0.2%) from 58.625%

Build # 10182608679

Build Type

push

github

Committed by

web-flow

Commit Message

Merge pull request #8845 from bitbandi/multiple-etcd-host

Allow multiple etcd host

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59.37

/config_builder.go

package lnd

import (
        "bytes"
        "context"
        "database/sql"
        "errors"
        "fmt"
        "net"
        "os"
        "path/filepath"
        "sort"
        "strconv"
        "strings"
        "sync/atomic"
        "time"

        "github.com/btcsuite/btcd/chaincfg"
        "github.com/btcsuite/btcd/chaincfg/chainhash"
        "github.com/btcsuite/btcd/wire"
        "github.com/btcsuite/btclog"
        "github.com/btcsuite/btcwallet/chain"
        "github.com/btcsuite/btcwallet/waddrmgr"
        "github.com/btcsuite/btcwallet/wallet"
        "github.com/btcsuite/btcwallet/walletdb"
        proxy "github.com/grpc-ecosystem/grpc-gateway/v2/runtime"
        "github.com/lightninglabs/neutrino"
        "github.com/lightninglabs/neutrino/blockntfns"
        "github.com/lightninglabs/neutrino/headerfs"
        "github.com/lightninglabs/neutrino/pushtx"
        "github.com/lightningnetwork/lnd/blockcache"
        "github.com/lightningnetwork/lnd/chainntnfs"
        "github.com/lightningnetwork/lnd/chainreg"
        "github.com/lightningnetwork/lnd/channeldb"
        "github.com/lightningnetwork/lnd/clock"
        "github.com/lightningnetwork/lnd/invoices"
        "github.com/lightningnetwork/lnd/keychain"
        "github.com/lightningnetwork/lnd/kvdb"
        "github.com/lightningnetwork/lnd/lncfg"
        "github.com/lightningnetwork/lnd/lnrpc"
        "github.com/lightningnetwork/lnd/lnwallet"
        "github.com/lightningnetwork/lnd/lnwallet/btcwallet"
        "github.com/lightningnetwork/lnd/lnwallet/rpcwallet"
        "github.com/lightningnetwork/lnd/macaroons"
        "github.com/lightningnetwork/lnd/rpcperms"
        "github.com/lightningnetwork/lnd/signal"
        "github.com/lightningnetwork/lnd/sqldb"
        "github.com/lightningnetwork/lnd/walletunlocker"
        "github.com/lightningnetwork/lnd/watchtower"
        "github.com/lightningnetwork/lnd/watchtower/wtclient"
        "github.com/lightningnetwork/lnd/watchtower/wtdb"
        "google.golang.org/grpc"
        "gopkg.in/macaroon-bakery.v2/bakery"
)

// GrpcRegistrar is an interface that must be satisfied by an external subserver
// that wants to be able to register its own gRPC server onto lnd's main
// grpc.Server instance.
type GrpcRegistrar interface {
        // RegisterGrpcSubserver is called for each net.Listener on which lnd
        // creates a grpc.Server instance. External subservers implementing this
        // method can then register their own gRPC server structs to the main
        // server instance.
        RegisterGrpcSubserver(*grpc.Server) error
}

// RestRegistrar is an interface that must be satisfied by an external subserver
// that wants to be able to register its own REST mux onto lnd's main
// proxy.ServeMux instance.
type RestRegistrar interface {
        // RegisterRestSubserver is called after lnd creates the main
        // proxy.ServeMux instance. External subservers implementing this method
        // can then register their own REST proxy stubs to the main server
        // instance.
        RegisterRestSubserver(context.Context, *proxy.ServeMux, string,
                []grpc.DialOption) error
}

// ExternalValidator is an interface that must be satisfied by an external
// macaroon validator.
type ExternalValidator interface {
        macaroons.MacaroonValidator

        // Permissions returns the permissions that the external validator is
        // validating. It is a map between the full HTTP URI of each RPC and its
        // required macaroon permissions. If multiple action/entity tuples are
        // specified per URI, they are all required. See rpcserver.go for a list
        // of valid action and entity values.
        Permissions() map[string][]bakery.Op
}

// DatabaseBuilder is an interface that must be satisfied by the implementation
// that provides lnd's main database backend instances.
type DatabaseBuilder interface {
        // BuildDatabase extracts the current databases that we'll use for
        // normal operation in the daemon. A function closure that closes all
        // opened databases is also returned.
        BuildDatabase(ctx context.Context) (*DatabaseInstances, func(), error)
}

// WalletConfigBuilder is an interface that must be satisfied by a custom wallet
// implementation.
type WalletConfigBuilder interface {
        // BuildWalletConfig is responsible for creating or unlocking and then
        // fully initializing a wallet.
        BuildWalletConfig(context.Context, *DatabaseInstances,
                *rpcperms.InterceptorChain,
                []*ListenerWithSignal) (*chainreg.PartialChainControl,
                *btcwallet.Config, func(), error)
}

// ChainControlBuilder is an interface that must be satisfied by a custom wallet
// implementation.
type ChainControlBuilder interface {
        // BuildChainControl is responsible for creating a fully populated chain
        // control instance from a wallet.
        BuildChainControl(*chainreg.PartialChainControl,
                *btcwallet.Config) (*chainreg.ChainControl, func(), error)
}

// ImplementationCfg is a struct that holds all configuration items for
// components that can be implemented outside lnd itself.
type ImplementationCfg struct {
        // GrpcRegistrar is a type that can register additional gRPC subservers
        // before the main gRPC server is started.
        GrpcRegistrar

        // RestRegistrar is a type that can register additional REST subservers
        // before the main REST proxy is started.
        RestRegistrar

        // ExternalValidator is a type that can provide external macaroon
        // validation.
        ExternalValidator

        // DatabaseBuilder is a type that can provide lnd's main database
        // backend instances.
        DatabaseBuilder

        // WalletConfigBuilder is a type that can provide a wallet configuration
        // with a fully loaded and unlocked wallet.
        WalletConfigBuilder

        // ChainControlBuilder is a type that can provide a custom wallet
        // implementation.
        ChainControlBuilder
}

// DefaultWalletImpl is the default implementation of our normal, btcwallet
// backed configuration.
type DefaultWalletImpl struct {
        cfg         *Config
        logger      btclog.Logger
        interceptor signal.Interceptor

        watchOnly        bool
        migrateWatchOnly bool
        pwService        *walletunlocker.UnlockerService
}

// NewDefaultWalletImpl creates a new default wallet implementation.
func NewDefaultWalletImpl(cfg *Config, logger btclog.Logger,
        interceptor signal.Interceptor, watchOnly bool) *DefaultWalletImpl {

        return &DefaultWalletImpl{
                cfg:         cfg,
                logger:      logger,
                interceptor: interceptor,
                watchOnly:   watchOnly,
                pwService:   createWalletUnlockerService(cfg),
        }
}

// RegisterRestSubserver is called after lnd creates the main proxy.ServeMux
// instance. External subservers implementing this method can then register
// their own REST proxy stubs to the main server instance.
//
// NOTE: This is part of the GrpcRegistrar interface.
func (d *DefaultWalletImpl) RegisterRestSubserver(ctx context.Context,
        mux *proxy.ServeMux, restProxyDest string,
        restDialOpts []grpc.DialOption) error {

        return lnrpc.RegisterWalletUnlockerHandlerFromEndpoint(
                ctx, mux, restProxyDest, restDialOpts,
        )
}

// RegisterGrpcSubserver is called for each net.Listener on which lnd creates a
// grpc.Server instance. External subservers implementing this method can then
// register their own gRPC server structs to the main server instance.
//
// NOTE: This is part of the GrpcRegistrar interface.
func (d *DefaultWalletImpl) RegisterGrpcSubserver(s *grpc.Server) error {
        lnrpc.RegisterWalletUnlockerServer(s, d.pwService)

        return nil
}

// ValidateMacaroon extracts the macaroon from the context's gRPC metadata,
// checks its signature, makes sure all specified permissions for the called
// method are contained within and finally ensures all caveat conditions are
// met. A non-nil error is returned if any of the checks fail.
//
// NOTE: This is part of the ExternalValidator interface.
func (d *DefaultWalletImpl) ValidateMacaroon(ctx context.Context,
        requiredPermissions []bakery.Op, fullMethod string) error {

        // Because the default implementation does not return any permissions,
        // we shouldn't be registered as an external validator at all and this
        // should never be invoked.
        return fmt.Errorf("default implementation does not support external " +
                "macaroon validation")
}

// Permissions returns the permissions that the external validator is
// validating. It is a map between the full HTTP URI of each RPC and its
// required macaroon permissions. If multiple action/entity tuples are specified
// per URI, they are all required. See rpcserver.go for a list of valid action
// and entity values.
//
// NOTE: This is part of the ExternalValidator interface.
func (d *DefaultWalletImpl) Permissions() map[string][]bakery.Op {
        return nil
}

// BuildWalletConfig is responsible for creating or unlocking and then
// fully initializing a wallet.
//
// NOTE: This is part of the WalletConfigBuilder interface.
func (d *DefaultWalletImpl) BuildWalletConfig(ctx context.Context,
        dbs *DatabaseInstances, interceptorChain *rpcperms.InterceptorChain,
        grpcListeners []*ListenerWithSignal) (*chainreg.PartialChainControl,
        *btcwallet.Config, func(), error) {

        // Keep track of our various cleanup functions. We use a defer function
        // as well to not repeat ourselves with every return statement.
        var (
                cleanUpTasks []func()
                earlyExit    = true
                cleanUp      = func() {
                        for _, fn := range cleanUpTasks {
                                if fn == nil {
                                        continue
                                }

                                fn()
                        }
                }
        )
        defer func() {
                if earlyExit {
                        cleanUp()
                }
        }()

        // Initialize a new block cache.
        blockCache := blockcache.NewBlockCache(d.cfg.BlockCacheSize)

        // Before starting the wallet, we'll create and start our Neutrino
        // light client instance, if enabled, in order to allow it to sync
        // while the rest of the daemon continues startup.
        mainChain := d.cfg.Bitcoin
        var neutrinoCS *neutrino.ChainService
        if mainChain.Node == "neutrino" {
                neutrinoBackend, neutrinoCleanUp, err := initNeutrinoBackend(
                        ctx, d.cfg, mainChain.ChainDir, blockCache,
                )
                if err != nil {
                        err := fmt.Errorf("unable to initialize neutrino "+
                                "backend: %v", err)
                        d.logger.Error(err)
                        return nil, nil, nil, err
                }
                cleanUpTasks = append(cleanUpTasks, neutrinoCleanUp)
                neutrinoCS = neutrinoBackend
        }

        var (
                walletInitParams = walletunlocker.WalletUnlockParams{
                        // In case we do auto-unlock, we need to be able to send
                        // into the channel without blocking so we buffer it.
                        MacResponseChan: make(chan []byte, 1),
                }
                privateWalletPw = lnwallet.DefaultPrivatePassphrase
                publicWalletPw  = lnwallet.DefaultPublicPassphrase
        )

        // If the user didn't request a seed, then we'll manually assume a
        // wallet birthday of now, as otherwise the seed would've specified
        // this information.
        walletInitParams.Birthday = time.Now()

        d.pwService.SetLoaderOpts([]btcwallet.LoaderOption{dbs.WalletDB})
        d.pwService.SetMacaroonDB(dbs.MacaroonDB)
        walletExists, err := d.pwService.WalletExists()
        if err != nil {
                return nil, nil, nil, err
        }

        if !walletExists {
                interceptorChain.SetWalletNotCreated()
        } else {
                interceptorChain.SetWalletLocked()
        }

        // If we've started in auto unlock mode, then a wallet should already
        // exist because we don't want to enable the RPC unlocker in that case
        // for security reasons (an attacker could inject their seed since the
        // RPC is unauthenticated). Only if the user explicitly wants to allow
        // wallet creation we don't error out here.
        if d.cfg.WalletUnlockPasswordFile != "" && !walletExists &&
                !d.cfg.WalletUnlockAllowCreate {

                return nil, nil, nil, fmt.Errorf("wallet unlock password file " +
                        "was specified but wallet does not exist; initialize " +
                        "the wallet before using auto unlocking")
        }

        // What wallet mode are we running in? We've already made sure the no
        // seed backup and auto unlock aren't both set during config parsing.
        switch {
        // No seed backup means we're also using the default password.
        case d.cfg.NoSeedBackup:
                // We continue normally, the default password has already been
                // set above.

        // A password for unlocking is provided in a file.
        case d.cfg.WalletUnlockPasswordFile != "" && walletExists:
                d.logger.Infof("Attempting automatic wallet unlock with " +
                        "password provided in file")
                pwBytes, err := os.ReadFile(d.cfg.WalletUnlockPasswordFile)
                if err != nil {
                        return nil, nil, nil, fmt.Errorf("error reading "+
                                "password from file %s: %v",
                                d.cfg.WalletUnlockPasswordFile, err)
                }

                // Remove any newlines at the end of the file. The lndinit tool
                // won't ever write a newline but maybe the file was provisioned
                // by another process or user.
                pwBytes = bytes.TrimRight(pwBytes, "\r\n")

                // We have the password now, we can ask the unlocker service to
                // do the unlock for us.
                unlockedWallet, unloadWalletFn, err := d.pwService.LoadAndUnlock(
                        pwBytes, 0,
                )
                if err != nil {
                        return nil, nil, nil, fmt.Errorf("error unlocking "+
                                "wallet with password from file: %v", err)
                }

                cleanUpTasks = append(cleanUpTasks, func() {
                        if err := unloadWalletFn(); err != nil {
                                d.logger.Errorf("Could not unload wallet: %v",
                                        err)
                        }
                })

                privateWalletPw = pwBytes
                publicWalletPw = pwBytes
                walletInitParams.Wallet = unlockedWallet
                walletInitParams.UnloadWallet = unloadWalletFn

        // If none of the automatic startup options are selected, we fall back
        // to the default behavior of waiting for the wallet creation/unlocking
        // over RPC.
        default:
                if err := d.interceptor.Notifier.NotifyReady(false); err != nil {
                        return nil, nil, nil, err
                }

                params, err := waitForWalletPassword(
                        d.cfg, d.pwService, []btcwallet.LoaderOption{dbs.WalletDB},
                        d.interceptor.ShutdownChannel(),
                )
                if err != nil {
                        err := fmt.Errorf("unable to set up wallet password "+
                                "listeners: %v", err)
                        d.logger.Error(err)
                        return nil, nil, nil, err
                }

                walletInitParams = *params
                privateWalletPw = walletInitParams.Password
                publicWalletPw = walletInitParams.Password
                cleanUpTasks = append(cleanUpTasks, func() {
                        if err := walletInitParams.UnloadWallet(); err != nil {
                                d.logger.Errorf("Could not unload wallet: %v",
                                        err)
                        }
                })

                if walletInitParams.RecoveryWindow > 0 {
                        d.logger.Infof("Wallet recovery mode enabled with "+
                                "address lookahead of %d addresses",
                                walletInitParams.RecoveryWindow)
                }
        }

        var macaroonService *macaroons.Service
        if !d.cfg.NoMacaroons {
                // Create the macaroon authentication/authorization service.
                rootKeyStore, err := macaroons.NewRootKeyStorage(dbs.MacaroonDB)
                if err != nil {
                        return nil, nil, nil, err
                }
                macaroonService, err = macaroons.NewService(
                        rootKeyStore, "lnd", walletInitParams.StatelessInit,
                        macaroons.IPLockChecker,
                        macaroons.CustomChecker(interceptorChain),
                )
                if err != nil {
                        err := fmt.Errorf("unable to set up macaroon "+
                                "authentication: %v", err)
                        d.logger.Error(err)
                        return nil, nil, nil, err
                }
                cleanUpTasks = append(cleanUpTasks, func() {
                        if err := macaroonService.Close(); err != nil {
                                d.logger.Errorf("Could not close macaroon "+
                                        "service: %v", err)
                        }
                })

                // 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 {
                        err := fmt.Errorf("unable to unlock macaroons: %w", err)
                        d.logger.Error(err)
                        return nil, nil, nil, err
                }

                // If we have a macaroon root key from the init wallet params,
                // set the root key before baking any macaroons.
                if len(walletInitParams.MacRootKey) > 0 {
                        err := macaroonService.SetRootKey(
                                walletInitParams.MacRootKey,
                        )
                        if err != nil {
                                return nil, nil, nil, err
                        }
                }

                // Send an admin macaroon to all our listeners that requested
                // one by setting a non-nil macaroon channel.
                adminMacBytes, err := bakeMacaroon(
                        ctx, macaroonService, adminPermissions(),
                )
                if err != nil {
                        return nil, nil, nil, err
                }
                for _, lis := range grpcListeners {
                        if lis.MacChan != nil {
                                lis.MacChan <- adminMacBytes
                        }
                }

                // In case we actually needed to unlock the wallet, we now need
                // to create an instance of the admin macaroon and send it to
                // the unlocker so it can forward it to the user. In no seed
                // backup mode, there's nobody listening on the channel and we'd
                // block here forever.
                if !d.cfg.NoSeedBackup {
                        // The channel is buffered by one element so writing
                        // should not block here.
                        walletInitParams.MacResponseChan <- adminMacBytes
                }

                // If the user requested a stateless initialization, no macaroon
                // files should be created.
                if !walletInitParams.StatelessInit {
                        // Create default macaroon files for lncli to use if
                        // they don't exist.
                        err = genDefaultMacaroons(
                                ctx, macaroonService, d.cfg.AdminMacPath,
                                d.cfg.ReadMacPath, d.cfg.InvoiceMacPath,
                        )
                        if err != nil {
                                err := fmt.Errorf("unable to create macaroons "+
                                        "%v", err)
                                d.logger.Error(err)
                                return nil, nil, nil, err
                        }
                }

                // As a security service to the user, if they requested
                // stateless initialization and there are macaroon files on disk
                // we log a warning.
                if walletInitParams.StatelessInit {
                        msg := "Found %s macaroon on disk (%s) even though " +
                                "--stateless_init was requested. Unencrypted " +
                                "state is accessible by the host system. You " +
                                "should change the password and use " +
                                "--new_mac_root_key with --stateless_init to " +
                                "clean up and invalidate old macaroons."

                        if lnrpc.FileExists(d.cfg.AdminMacPath) {
                                d.logger.Warnf(msg, "admin", d.cfg.AdminMacPath)
                        }
                        if lnrpc.FileExists(d.cfg.ReadMacPath) {
                                d.logger.Warnf(msg, "readonly", d.cfg.ReadMacPath)
                        }
                        if lnrpc.FileExists(d.cfg.InvoiceMacPath) {
                                d.logger.Warnf(msg, "invoice", d.cfg.InvoiceMacPath)
                        }
                }

                // We add the macaroon service to our RPC interceptor. This
                // will start checking macaroons against permissions on every
                // RPC invocation.
                interceptorChain.AddMacaroonService(macaroonService)
        }

        // Now that the wallet password has been provided, transition the RPC
        // state into Unlocked.
        interceptorChain.SetWalletUnlocked()

        // Since calls to the WalletUnlocker service wait for a response on the
        // macaroon channel, we close it here to make sure they return in case
        // we did not return the admin macaroon above. This will be the case if
        // --no-macaroons is used.
        close(walletInitParams.MacResponseChan)

        // We'll also close all the macaroon channels since lnd is done sending
        // macaroon data over it.
        for _, lis := range grpcListeners {
                if lis.MacChan != nil {
                        close(lis.MacChan)
                }
        }

        // With the information parsed from the configuration, create valid
        // instances of the pertinent interfaces required to operate the
        // Lightning Network Daemon.
        //
        // When we create the chain control, we need storage for the height
        // hints and also the wallet itself, for these two we want them to be
        // replicated, so we'll pass in the remote channel DB instance.
        chainControlCfg := &chainreg.Config{
                Bitcoin:                     d.cfg.Bitcoin,
                HeightHintCacheQueryDisable: d.cfg.HeightHintCacheQueryDisable,
                NeutrinoMode:                d.cfg.NeutrinoMode,
                BitcoindMode:                d.cfg.BitcoindMode,
                BtcdMode:                    d.cfg.BtcdMode,
                HeightHintDB:                dbs.HeightHintDB,
                ChanStateDB:                 dbs.ChanStateDB.ChannelStateDB(),
                NeutrinoCS:                  neutrinoCS,
                ActiveNetParams:             d.cfg.ActiveNetParams,
                FeeURL:                      d.cfg.FeeURL,
                Fee: &lncfg.Fee{
                        URL:              d.cfg.Fee.URL,
                        MinUpdateTimeout: d.cfg.Fee.MinUpdateTimeout,
                        MaxUpdateTimeout: d.cfg.Fee.MaxUpdateTimeout,
                },
                Dialer: func(addr string) (net.Conn, error) {
                        return d.cfg.net.Dial(
                                "tcp", addr, d.cfg.ConnectionTimeout,
                        )
                },
                BlockCache:         blockCache,
                WalletUnlockParams: &walletInitParams,
        }

        // Let's go ahead and create the partial chain control now that is only
        // dependent on our configuration and doesn't require any wallet
        // specific information.
        partialChainControl, pccCleanup, err := chainreg.NewPartialChainControl(
                chainControlCfg,
        )
        cleanUpTasks = append(cleanUpTasks, pccCleanup)
        if err != nil {
                err := fmt.Errorf("unable to create partial chain control: %w",
                        err)
                d.logger.Error(err)
                return nil, nil, nil, err
        }

        walletConfig := &btcwallet.Config{
                PrivatePass:      privateWalletPw,
                PublicPass:       publicWalletPw,
                Birthday:         walletInitParams.Birthday,
                RecoveryWindow:   walletInitParams.RecoveryWindow,
                NetParams:        d.cfg.ActiveNetParams.Params,
                CoinType:         d.cfg.ActiveNetParams.CoinType,
                Wallet:           walletInitParams.Wallet,
                LoaderOptions:    []btcwallet.LoaderOption{dbs.WalletDB},
                ChainSource:      partialChainControl.ChainSource,
                WatchOnly:        d.watchOnly,
                MigrateWatchOnly: d.migrateWatchOnly,
        }

        // Parse coin selection strategy.
        switch d.cfg.CoinSelectionStrategy {
        case "largest":
                walletConfig.CoinSelectionStrategy = wallet.CoinSelectionLargest

        case "random":
                walletConfig.CoinSelectionStrategy = wallet.CoinSelectionRandom

        default:
                return nil, nil, nil, fmt.Errorf("unknown coin selection "+
                        "strategy %v", d.cfg.CoinSelectionStrategy)
        }

        earlyExit = false
        return partialChainControl, walletConfig, cleanUp, nil
}

// proxyBlockEpoch proxies a block epoch subsections to the underlying neutrino
// rebroadcaster client.
func proxyBlockEpoch(notifier chainntnfs.ChainNotifier,
) func() (*blockntfns.Subscription, error) {

        return func() (*blockntfns.Subscription, error) {
                blockEpoch, err := notifier.RegisterBlockEpochNtfn(
                        nil,
                )
                if err != nil {
                        return nil, err
                }

                sub := blockntfns.Subscription{
                        Notifications: make(chan blockntfns.BlockNtfn, 6),
                        Cancel:        blockEpoch.Cancel,
                }
                go func() {
                        for blk := range blockEpoch.Epochs {
                                ntfn := blockntfns.NewBlockConnected(
                                        *blk.BlockHeader,
                                        uint32(blk.Height),
                                )

                                sub.Notifications <- ntfn
                        }
                }()

                return &sub, nil
        }
}

// walletReBroadcaster is a simple wrapper around the pushtx.Broadcaster
// interface to adhere to the expanded lnwallet.Rebroadcaster interface.
type walletReBroadcaster struct {
        started atomic.Bool

        *pushtx.Broadcaster
}

// newWalletReBroadcaster creates a new instance of the walletReBroadcaster.
func newWalletReBroadcaster(
        broadcaster *pushtx.Broadcaster) *walletReBroadcaster {

        return &walletReBroadcaster{
                Broadcaster: broadcaster,
        }
}

// Start launches all goroutines the rebroadcaster needs to operate.
func (w *walletReBroadcaster) Start() error {
        defer w.started.Store(true)

        return w.Broadcaster.Start()
}

// Started returns true if the broadcaster is already active.
func (w *walletReBroadcaster) Started() bool {
        return w.started.Load()
}

// BuildChainControl is responsible for creating a fully populated chain
// control instance from a wallet.
//
// NOTE: This is part of the ChainControlBuilder interface.
func (d *DefaultWalletImpl) BuildChainControl(
        partialChainControl *chainreg.PartialChainControl,
        walletConfig *btcwallet.Config) (*chainreg.ChainControl, func(), error) {

        walletController, err := btcwallet.New(
                *walletConfig, partialChainControl.Cfg.BlockCache,
        )
        if err != nil {
                err := fmt.Errorf("unable to create wallet controller: %w", err)
                d.logger.Error(err)
                return nil, nil, err
        }

        keyRing := keychain.NewBtcWalletKeyRing(
                walletController.InternalWallet(), walletConfig.CoinType,
        )

        // Create, and start the lnwallet, which handles the core payment
        // channel logic, and exposes control via proxy state machines.
        lnWalletConfig := lnwallet.Config{
                Database:              partialChainControl.Cfg.ChanStateDB,
                Notifier:              partialChainControl.ChainNotifier,
                WalletController:      walletController,
                Signer:                walletController,
                FeeEstimator:          partialChainControl.FeeEstimator,
                SecretKeyRing:         keyRing,
                ChainIO:               walletController,
                NetParams:             *walletConfig.NetParams,
                CoinSelectionStrategy: walletConfig.CoinSelectionStrategy,
        }

        // The broadcast is already always active for neutrino nodes, so we
        // don't want to create a rebroadcast loop.
        if partialChainControl.Cfg.NeutrinoCS == nil {
                cs := partialChainControl.ChainSource
                broadcastCfg := pushtx.Config{
                        Broadcast: func(tx *wire.MsgTx) error {
                                _, err := cs.SendRawTransaction(
                                        tx, true,
                                )

                                return err
                        },
                        SubscribeBlocks: proxyBlockEpoch(
                                partialChainControl.ChainNotifier,
                        ),
                        RebroadcastInterval: pushtx.DefaultRebroadcastInterval,
                        // In case the backend is different from neutrino we
                        // make sure that broadcast backend errors are mapped
                        // to the neutrino broadcastErr.
                        MapCustomBroadcastError: func(err error) error {
                                rpcErr := cs.MapRPCErr(err)
                                return broadcastErrorMapper(rpcErr)
                        },
                }

                lnWalletConfig.Rebroadcaster = newWalletReBroadcaster(
                        pushtx.NewBroadcaster(&broadcastCfg),
                )
        }

        // We've created the wallet configuration now, so we can finish
        // initializing the main chain control.
        activeChainControl, cleanUp, err := chainreg.NewChainControl(
                lnWalletConfig, walletController, partialChainControl,
        )
        if err != nil {
                err := fmt.Errorf("unable to create chain control: %w", err)
                d.logger.Error(err)
                return nil, nil, err
        }

        return activeChainControl, cleanUp, nil
}

// RPCSignerWalletImpl is a wallet implementation that uses a remote signer over
// an RPC interface.
type RPCSignerWalletImpl struct {
        // DefaultWalletImpl is the embedded instance of the default
        // implementation that the remote signer uses as its watch-only wallet
        // for keeping track of addresses and UTXOs.
        *DefaultWalletImpl
}

// NewRPCSignerWalletImpl creates a new instance of the remote signing wallet
// implementation.
func NewRPCSignerWalletImpl(cfg *Config, logger btclog.Logger,
        interceptor signal.Interceptor,
        migrateWatchOnly bool) *RPCSignerWalletImpl {

        return &RPCSignerWalletImpl{
                DefaultWalletImpl: &DefaultWalletImpl{
                        cfg:              cfg,
                        logger:           logger,
                        interceptor:      interceptor,
                        watchOnly:        true,
                        migrateWatchOnly: migrateWatchOnly,
                        pwService:        createWalletUnlockerService(cfg),
                },
        }
}

// BuildChainControl is responsible for creating or unlocking and then fully
// initializing a wallet and returning it as part of a fully populated chain
// control instance.
//
// NOTE: This is part of the ChainControlBuilder interface.
func (d *RPCSignerWalletImpl) BuildChainControl(
        partialChainControl *chainreg.PartialChainControl,
        walletConfig *btcwallet.Config) (*chainreg.ChainControl, func(), error) {

        walletController, err := btcwallet.New(
                *walletConfig, partialChainControl.Cfg.BlockCache,
        )
        if err != nil {
                err := fmt.Errorf("unable to create wallet controller: %w", err)
                d.logger.Error(err)
                return nil, nil, err
        }

        baseKeyRing := keychain.NewBtcWalletKeyRing(
                walletController.InternalWallet(), walletConfig.CoinType,
        )

        rpcKeyRing, err := rpcwallet.NewRPCKeyRing(
                baseKeyRing, walletController,
                d.DefaultWalletImpl.cfg.RemoteSigner, walletConfig.NetParams,
        )
        if err != nil {
                err := fmt.Errorf("unable to create RPC remote signing wallet "+
                        "%v", err)
                d.logger.Error(err)
                return nil, nil, err
        }

        // Create, and start the lnwallet, which handles the core payment
        // channel logic, and exposes control via proxy state machines.
        lnWalletConfig := lnwallet.Config{
                Database:              partialChainControl.Cfg.ChanStateDB,
                Notifier:              partialChainControl.ChainNotifier,
                WalletController:      rpcKeyRing,
                Signer:                rpcKeyRing,
                FeeEstimator:          partialChainControl.FeeEstimator,
                SecretKeyRing:         rpcKeyRing,
                ChainIO:               walletController,
                NetParams:             *walletConfig.NetParams,
                CoinSelectionStrategy: walletConfig.CoinSelectionStrategy,
        }

        // We've created the wallet configuration now, so we can finish
        // initializing the main chain control.
        activeChainControl, cleanUp, err := chainreg.NewChainControl(
                lnWalletConfig, rpcKeyRing, partialChainControl,
        )
        if err != nil {
                err := fmt.Errorf("unable to create chain control: %w", err)
                d.logger.Error(err)
                return nil, nil, err
        }

        return activeChainControl, cleanUp, nil
}

// DatabaseInstances is a struct that holds all instances to the actual
// databases that are used in lnd.
type DatabaseInstances struct {
        // GraphDB is the database that stores the channel graph used for path
        // finding.
        //
        // NOTE/TODO: This currently _needs_ to be the same instance as the
        // ChanStateDB below until the separation of the two databases is fully
        // complete!
        GraphDB *channeldb.DB

        // ChanStateDB is the database that stores all of our node's channel
        // state.
        //
        // NOTE/TODO: This currently _needs_ to be the same instance as the
        // GraphDB above until the separation of the two databases is fully
        // complete!
        ChanStateDB *channeldb.DB

        // HeightHintDB is the database that stores height hints for spends.
        HeightHintDB kvdb.Backend

        // InvoiceDB is the database that stores information about invoices.
        InvoiceDB invoices.InvoiceDB

        // MacaroonDB is the database that stores macaroon root keys.
        MacaroonDB kvdb.Backend

        // DecayedLogDB is the database that stores p2p related encryption
        // information.
        DecayedLogDB kvdb.Backend

        // TowerClientDB is the database that stores the watchtower client's
        // configuration.
        TowerClientDB wtclient.DB

        // TowerServerDB is the database that stores the watchtower server's
        // configuration.
        TowerServerDB watchtower.DB

        // WalletDB is the configuration for loading the wallet database using
        // the btcwallet's loader.
        WalletDB btcwallet.LoaderOption

        // NativeSQLStore is a pointer to a native SQL store that can be used
        // for native SQL queries for tables that already support it. This may
        // be nil if the use-native-sql flag was not set.
        NativeSQLStore *sqldb.BaseDB
}

// DefaultDatabaseBuilder is a type that builds the default database backends
// for lnd, using the given configuration to decide what actual implementation
// to use.
type DefaultDatabaseBuilder struct {
        cfg    *Config
        logger btclog.Logger
}

// NewDefaultDatabaseBuilder returns a new instance of the default database
// builder.
func NewDefaultDatabaseBuilder(cfg *Config,
        logger btclog.Logger) *DefaultDatabaseBuilder {

        return &DefaultDatabaseBuilder{
                cfg:    cfg,
                logger: logger,
        }
}

// BuildDatabase extracts the current databases that we'll use for normal
// operation in the daemon. A function closure that closes all opened databases
// is also returned.
func (d *DefaultDatabaseBuilder) BuildDatabase(
        ctx context.Context) (*DatabaseInstances, func(), error) {

        d.logger.Infof("Opening the main database, this might take a few " +
                "minutes...")

        cfg := d.cfg
        if cfg.DB.Backend == lncfg.BoltBackend {
                d.logger.Infof("Opening bbolt database, sync_freelist=%v, "+
                        "auto_compact=%v", !cfg.DB.Bolt.NoFreelistSync,
                        cfg.DB.Bolt.AutoCompact)
        }

        startOpenTime := time.Now()

        databaseBackends, err := cfg.DB.GetBackends(
                ctx, cfg.graphDatabaseDir(), cfg.networkDir, filepath.Join(
                        cfg.Watchtower.TowerDir, BitcoinChainName,
                        lncfg.NormalizeNetwork(cfg.ActiveNetParams.Name),
                ), cfg.WtClient.Active, cfg.Watchtower.Active, d.logger,
        )
        if err != nil {
                return nil, nil, fmt.Errorf("unable to obtain database "+
                        "backends: %v", err)
        }

        // With the full remote mode we made sure both the graph and channel
        // state DB point to the same local or remote DB and the same namespace
        // within that DB.
        dbs := &DatabaseInstances{
                HeightHintDB:   databaseBackends.HeightHintDB,
                MacaroonDB:     databaseBackends.MacaroonDB,
                DecayedLogDB:   databaseBackends.DecayedLogDB,
                WalletDB:       databaseBackends.WalletDB,
                NativeSQLStore: databaseBackends.NativeSQLStore,
        }
        cleanUp := func() {
                // We can just close the returned close functions directly. Even
                // if we decorate the channel DB with an additional struct, its
                // close function still just points to the kvdb backend.
                for name, closeFunc := range databaseBackends.CloseFuncs {
                        if err := closeFunc(); err != nil {
                                d.logger.Errorf("Error closing %s "+
                                        "database: %v", name, err)
                        }
                }
        }
        if databaseBackends.Remote {
                d.logger.Infof("Using remote %v database! Creating "+
                        "graph and channel state DB instances", cfg.DB.Backend)
        } else {
                d.logger.Infof("Creating local graph and channel state DB " +
                        "instances")
        }

        dbOptions := []channeldb.OptionModifier{
                channeldb.OptionSetRejectCacheSize(cfg.Caches.RejectCacheSize),
                channeldb.OptionSetChannelCacheSize(
                        cfg.Caches.ChannelCacheSize,
                ),
                channeldb.OptionSetBatchCommitInterval(
                        cfg.DB.BatchCommitInterval,
                ),
                channeldb.OptionDryRunMigration(cfg.DryRunMigration),
                channeldb.OptionSetUseGraphCache(!cfg.DB.NoGraphCache),
                channeldb.OptionKeepFailedPaymentAttempts(
                        cfg.KeepFailedPaymentAttempts,
                ),
                channeldb.OptionStoreFinalHtlcResolutions(
                        cfg.StoreFinalHtlcResolutions,
                ),
                channeldb.OptionPruneRevocationLog(cfg.DB.PruneRevocation),
                channeldb.OptionNoRevLogAmtData(cfg.DB.NoRevLogAmtData),
        }

        // We want to pre-allocate the channel graph cache according to what we
        // expect for mainnet to speed up memory allocation.
        if cfg.ActiveNetParams.Name == chaincfg.MainNetParams.Name {
                dbOptions = append(
                        dbOptions, channeldb.OptionSetPreAllocCacheNumNodes(
                                channeldb.DefaultPreAllocCacheNumNodes,
                        ),
                )
        }

        // Otherwise, we'll open two instances, one for the state we only need
        // locally, and the other for things we want to ensure are replicated.
        dbs.GraphDB, err = channeldb.CreateWithBackend(
                databaseBackends.GraphDB, dbOptions...,
        )
        switch {
        // Give the DB a chance to dry run the migration. Since we know that
        // both the channel state and graph DBs are still always behind the same
        // backend, we know this would be applied to both of those DBs.
        case err == channeldb.ErrDryRunMigrationOK:
                d.logger.Infof("Graph DB dry run migration successful")
                return nil, nil, err

        case err != nil:
                cleanUp()

                err := fmt.Errorf("unable to open graph DB: %w", err)
                d.logger.Error(err)
                return nil, nil, err
        }

        // For now, we don't _actually_ split the graph and channel state DBs on
        // the code level. Since they both are based upon the *channeldb.DB
        // struct it will require more refactoring to fully separate them. With
        // the full remote mode we at least know for now that they both point to
        // the same DB backend (and also namespace within that) so we only need
        // to apply any migration once.
        //
        // TODO(guggero): Once the full separation of anything graph related
        // from the channeldb.DB is complete, the decorated instance of the
        // channel state DB should be created here individually instead of just
        // using the same struct (and DB backend) instance.
        dbs.ChanStateDB = dbs.GraphDB

        // Instantiate a native SQL invoice store if the flag is set.
        if d.cfg.DB.UseNativeSQL {
                // KV invoice db resides in the same database as the graph and
                // channel state DB. Let's query the database to see if we have
                // any invoices there. If we do, we won't allow the user to
                // start lnd with native SQL enabled, as we don't currently
                // migrate the invoices to the new database schema.
                invoiceSlice, err := dbs.GraphDB.QueryInvoices(
                        ctx, invoices.InvoiceQuery{
                                NumMaxInvoices: 1,
                        },
                )
                if err != nil {
                        cleanUp()
                        d.logger.Errorf("Unable to query KV invoice DB: %v",
                                err)

                        return nil, nil, err
                }

                if len(invoiceSlice.Invoices) > 0 {
                        cleanUp()
                        err := fmt.Errorf("found invoices in the KV invoice " +
                                "DB, migration to native SQL is not yet " +
                                "supported")
                        d.logger.Error(err)

                        return nil, nil, err
                }

                executor := sqldb.NewTransactionExecutor(
                        dbs.NativeSQLStore,
                        func(tx *sql.Tx) invoices.SQLInvoiceQueries {
                                return dbs.NativeSQLStore.WithTx(tx)
                        },
                )

                dbs.InvoiceDB = invoices.NewSQLStore(
                        executor, clock.NewDefaultClock(),
                )
        } else {
                dbs.InvoiceDB = dbs.GraphDB
        }

        // Wrap the watchtower client DB and make sure we clean up.
        if cfg.WtClient.Active {
                dbs.TowerClientDB, err = wtdb.OpenClientDB(
                        databaseBackends.TowerClientDB,
                )
                if err != nil {
                        cleanUp()

                        err := fmt.Errorf("unable to open %s database: %w",
                                lncfg.NSTowerClientDB, err)
                        d.logger.Error(err)
                        return nil, nil, err
                }
        }

        // Wrap the watchtower server DB and make sure we clean up.
        if cfg.Watchtower.Active {
                dbs.TowerServerDB, err = wtdb.OpenTowerDB(
                        databaseBackends.TowerServerDB,
                )
                if err != nil {
                        cleanUp()

                        err := fmt.Errorf("unable to open %s database: %w",
                                lncfg.NSTowerServerDB, err)
                        d.logger.Error(err)
                        return nil, nil, err
                }
        }

        openTime := time.Since(startOpenTime)
        d.logger.Infof("Database(s) now open (time_to_open=%v)!", openTime)

        return dbs, cleanUp, nil
}

// waitForWalletPassword blocks until a password is provided by the user to
// this RPC server.
func waitForWalletPassword(cfg *Config,
        pwService *walletunlocker.UnlockerService,
        loaderOpts []btcwallet.LoaderOption, shutdownChan <-chan struct{}) (
        *walletunlocker.WalletUnlockParams, error) {

        // Wait for user to provide the password.
        ltndLog.Infof("Waiting for wallet encryption password. Use `lncli " +
                "create` to create a wallet, `lncli unlock` to unlock an " +
                "existing wallet, or `lncli changepassword` to change the " +
                "password of an existing wallet and unlock it.")

        // 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 {
        // The wallet is being created for the first time, we'll check to see
        // if the user provided any entropy for seed creation. If so, then
        // we'll create the wallet early to load the seed.
        case initMsg := <-pwService.InitMsgs:
                password := initMsg.Passphrase
                cipherSeed := initMsg.WalletSeed
                extendedKey := initMsg.WalletExtendedKey
                watchOnlyAccounts := initMsg.WatchOnlyAccounts
                recoveryWindow := initMsg.RecoveryWindow

                // Before we proceed, we'll check the internal version of the
                // seed. If it's greater than the current key derivation
                // version, then we'll return an error as we don't understand
                // this.
                if cipherSeed != nil &&
                        !keychain.IsKnownVersion(cipherSeed.InternalVersion) {

                        return nil, fmt.Errorf("invalid internal "+
                                "seed version %v, current max version is %v",
                                cipherSeed.InternalVersion,
                                keychain.CurrentKeyDerivationVersion)
                }

                loader, err := btcwallet.NewWalletLoader(
                        cfg.ActiveNetParams.Params, recoveryWindow,
                        loaderOpts...,
                )
                if err != nil {
                        return nil, err
                }

                // With the seed, we can now use the wallet loader to create
                // the wallet, then pass it back to avoid unlocking it again.
                var (
                        birthday  time.Time
                        newWallet *wallet.Wallet
                )
                switch {
                // A normal cipher seed was given, use the birthday encoded in
                // it and create the wallet from that.
                case cipherSeed != nil:
                        birthday = cipherSeed.BirthdayTime()
                        newWallet, err = loader.CreateNewWallet(
                                password, password, cipherSeed.Entropy[:],
                                birthday,
                        )

                // No seed was given, we're importing a wallet from its extended
                // private key.
                case extendedKey != nil:
                        birthday = initMsg.ExtendedKeyBirthday
                        newWallet, err = loader.CreateNewWalletExtendedKey(
                                password, password, extendedKey, birthday,
                        )

                // Neither seed nor extended private key was given, so maybe the
                // third option was chosen, the watch-only initialization. In
                // this case we need to import each of the xpubs individually.
                case watchOnlyAccounts != nil:
                        if !cfg.RemoteSigner.Enable {
                                return nil, fmt.Errorf("cannot initialize " +
                                        "watch only wallet with remote " +
                                        "signer config disabled")
                        }

                        birthday = initMsg.WatchOnlyBirthday
                        newWallet, err = loader.CreateNewWatchingOnlyWallet(
                                password, birthday,
                        )
                        if err != nil {
                                break
                        }

                        err = importWatchOnlyAccounts(newWallet, initMsg)

                default:
                        // The unlocker service made sure either the cipher seed
                        // or the extended key is set so, we shouldn't get here.
                        // The default case is just here for readability and
                        // completeness.
                        err = fmt.Errorf("cannot create wallet, neither seed " +
                                "nor extended key was given")
                }
                if err != nil {
                        // Don't leave the file open in case the new wallet
                        // could not be created for whatever reason.
                        if err := loader.UnloadWallet(); err != nil {
                                ltndLog.Errorf("Could not unload new "+
                                        "wallet: %v", err)
                        }
                        return nil, err
                }

                // For new wallets, the ResetWalletTransactions flag is a no-op.
                if cfg.ResetWalletTransactions {
                        ltndLog.Warnf("Ignoring reset-wallet-transactions " +
                                "flag for new wallet as it has no effect")
                }

                return &walletunlocker.WalletUnlockParams{
                        Password:        password,
                        Birthday:        birthday,
                        RecoveryWindow:  recoveryWindow,
                        Wallet:          newWallet,
                        ChansToRestore:  initMsg.ChanBackups,
                        UnloadWallet:    loader.UnloadWallet,
                        StatelessInit:   initMsg.StatelessInit,
                        MacResponseChan: pwService.MacResponseChan,
                        MacRootKey:      initMsg.MacRootKey,
                }, nil

        // The wallet has already been created in the past, and is simply being
        // unlocked. So we'll just return these passphrases.
        case unlockMsg := <-pwService.UnlockMsgs:
                // Resetting the transactions is something the user likely only
                // wants to do once so we add a prominent warning to the log to
                // remind the user to turn off the setting again after
                // successful completion.
                if cfg.ResetWalletTransactions {
                        ltndLog.Warnf("Dropped all transaction history from " +
                                "on-chain wallet. Remember to disable " +
                                "reset-wallet-transactions flag for next " +
                                "start of lnd")
                }

                return &walletunlocker.WalletUnlockParams{
                        Password:        unlockMsg.Passphrase,
                        RecoveryWindow:  unlockMsg.RecoveryWindow,
                        Wallet:          unlockMsg.Wallet,
                        ChansToRestore:  unlockMsg.ChanBackups,
                        UnloadWallet:    unlockMsg.UnloadWallet,
                        StatelessInit:   unlockMsg.StatelessInit,
                        MacResponseChan: pwService.MacResponseChan,
                }, nil

        // If we got a shutdown signal we just return with an error immediately
        case <-shutdownChan:
                return nil, fmt.Errorf("shutting down")
        }
}

// importWatchOnlyAccounts imports all individual account xpubs into our wallet
// which we created as watch-only.
func importWatchOnlyAccounts(wallet *wallet.Wallet,
        initMsg *walletunlocker.WalletInitMsg) error {

        scopes := make([]waddrmgr.ScopedIndex, 0, len(initMsg.WatchOnlyAccounts))
        for scope := range initMsg.WatchOnlyAccounts {
                scopes = append(scopes, scope)
        }

        // We need to import the accounts in the correct order, otherwise the
        // indices will be incorrect.
        sort.Slice(scopes, func(i, j int) bool {
                return scopes[i].Scope.Purpose < scopes[j].Scope.Purpose ||
                        scopes[i].Index < scopes[j].Index
        })

        for _, scope := range scopes {
                addrSchema := waddrmgr.ScopeAddrMap[waddrmgr.KeyScopeBIP0084]

                // We want witness pubkey hash by default, except for BIP49
                // where we want mixed and BIP86 where we want taproot address
                // formats.
                switch scope.Scope.Purpose {
                case waddrmgr.KeyScopeBIP0049Plus.Purpose,
                        waddrmgr.KeyScopeBIP0086.Purpose:

                        addrSchema = waddrmgr.ScopeAddrMap[scope.Scope]
                }

                // We want a human-readable account name. But for the default
                // on-chain wallet we actually need to call it "default" to make
                // sure everything works correctly.
                name := fmt.Sprintf("%s/%d'", scope.Scope.String(), scope.Index)
                if scope.Index == 0 {
                        name = "default"
                }

                _, err := wallet.ImportAccountWithScope(
                        name, initMsg.WatchOnlyAccounts[scope],
                        initMsg.WatchOnlyMasterFingerprint, scope.Scope,
                        addrSchema,
                )
                if err != nil {
                        return fmt.Errorf("could not import account %v: %w",
                                name, err)
                }
        }

        return nil
}

// initNeutrinoBackend inits a new instance of the neutrino light client
// backend given a target chain directory to store the chain state.
func initNeutrinoBackend(ctx context.Context, cfg *Config, chainDir string,
        blockCache *blockcache.BlockCache) (*neutrino.ChainService,
        func(), error) {

        // Both channel validation flags are false by default but their meaning
        // is the inverse of each other. Therefore both cannot be true. For
        // every other case, the neutrino.validatechannels overwrites the
        // routing.assumechanvalid value.
        if cfg.NeutrinoMode.ValidateChannels && cfg.Routing.AssumeChannelValid {
                return nil, nil, fmt.Errorf("can't set both " +
                        "neutrino.validatechannels and routing." +
                        "assumechanvalid to true at the same time")
        }
        cfg.Routing.AssumeChannelValid = !cfg.NeutrinoMode.ValidateChannels

        // 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, lncfg.NormalizeNetwork(cfg.ActiveNetParams.Name),
        )

        // Ensure that the neutrino db path exists.
        if err := os.MkdirAll(dbPath, 0700); err != nil {
                return nil, nil, err
        }

        var (
                db  walletdb.DB
                err error
        )
        switch {
        case cfg.DB.Backend == kvdb.SqliteBackendName:
                sqliteConfig := lncfg.GetSqliteConfigKVDB(cfg.DB.Sqlite)
                db, err = kvdb.Open(
                        kvdb.SqliteBackendName, ctx, sqliteConfig, dbPath,
                        lncfg.SqliteNeutrinoDBName, lncfg.NSNeutrinoDB,
                )

        default:
                dbName := filepath.Join(dbPath, "neutrino.db")
                db, err = walletdb.Create(
                        "bdb", dbName, !cfg.SyncFreelist, cfg.DB.Bolt.DBTimeout,
                )
        }
        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:  *cfg.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(),
                                cfg.ConnectionTimeout,
                        )
                },
                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,
                BlockCache:         blockCache.Cache,
                BroadcastTimeout:   cfg.NeutrinoMode.BroadcastTimeout,
                PersistToDisk:      cfg.NeutrinoMode.PersistFilters,
        }

        neutrino.MaxPeers = 8
        neutrino.BanDuration = time.Hour * 48
        neutrino.UserAgentName = cfg.NeutrinoMode.UserAgentName
        neutrino.UserAgentVersion = cfg.NeutrinoMode.UserAgentVersion

        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() {
                if err := neutrinoCS.Stop(); err != nil {
                        ltndLog.Infof("Unable to stop neutrino light client: "+
                                "%v", err)
                }
                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: %w", err)
        }

        hash, err := chainhash.NewHashFromStr(split[1])
        if err != nil {
                return nil, fmt.Errorf("invalid filter header hash: %w", err)
        }

        return &headerfs.FilterHeader{
                Height:     uint32(height),
                FilterHash: *hash,
        }, nil
}

// broadcastErrorMapper maps errors from bitcoin backends other than neutrino to
// the neutrino BroadcastError which allows the Rebroadcaster which currently
// resides in the neutrino package to use all of its functionalities.
func broadcastErrorMapper(err error) error {
        var returnErr error

        // We only filter for specific backend errors which are relevant for the
        // Rebroadcaster.
        switch {
        // This makes sure the tx is removed from the rebroadcaster once it is
        // confirmed.
        case errors.Is(err, chain.ErrTxAlreadyKnown),
                errors.Is(err, chain.ErrTxAlreadyConfirmed):

                returnErr = &pushtx.BroadcastError{
                        Code:   pushtx.Confirmed,
                        Reason: err.Error(),
                }

        // Transactions which are still in mempool but might fall out because
        // of low fees are rebroadcasted despite of their backend error.
        case errors.Is(err, chain.ErrTxAlreadyInMempool):
                returnErr = &pushtx.BroadcastError{
                        Code:   pushtx.Mempool,
                        Reason: err.Error(),
                }

        // Transactions which are not accepted into mempool because of low fees
        // in the first place are rebroadcasted despite of their backend error.
        // Mempool conditions change over time so it makes sense to retry
        // publishing the transaction. Moreover we log the detailed error so the
        // user can intervene and increase the size of his mempool.
        case errors.Is(err, chain.ErrMempoolMinFeeNotMet):
                ltndLog.Warnf("Error while broadcasting transaction: %v", err)

                returnErr = &pushtx.BroadcastError{
                        Code:   pushtx.Mempool,
                        Reason: err.Error(),
                }
        }

        return returnErr
}

lightningnetwork / lnd / 10182608679

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