lightningnetwork / lnd / 11216766535

package lnwallet

import (

        "errors"

        "fmt"

        "sync"

        "time"

        "github.com/btcsuite/btcd/btcec/v2"

        "github.com/btcsuite/btcd/btcec/v2/ecdsa"

        "github.com/btcsuite/btcd/btcutil"

        "github.com/btcsuite/btcd/btcutil/hdkeychain"

        "github.com/btcsuite/btcd/btcutil/psbt"

        "github.com/btcsuite/btcd/chaincfg/chainhash"

        "github.com/btcsuite/btcd/txscript"

        "github.com/btcsuite/btcd/wire"

        "github.com/btcsuite/btcwallet/waddrmgr"

        base "github.com/btcsuite/btcwallet/wallet"

        "github.com/btcsuite/btcwallet/wallet/txauthor"

        "github.com/btcsuite/btcwallet/wtxmgr"

        "github.com/lightningnetwork/lnd/fn"

        "github.com/lightningnetwork/lnd/keychain"

        "github.com/lightningnetwork/lnd/lnwallet/chainfee"

        "github.com/lightningnetwork/lnd/lnwallet/chanvalidate"

        "github.com/lightningnetwork/lnd/lnwire"

)

const (

        // DefaultAccountName is the name for the default account used to manage

        // on-chain funds within the wallet.

        DefaultAccountName = "default"

)

// AddressType is an enum-like type which denotes the possible address types

// WalletController supports.

type AddressType uint8

// AccountAddressMap maps the account properties to an array of

// address properties.

type AccountAddressMap map[*waddrmgr.AccountProperties][]AddressProperty

const (

        // UnknownAddressType represents an output with an unknown or non-standard

        // script.

        UnknownAddressType AddressType = iota

        // WitnessPubKey represents a p2wkh address.

        WitnessPubKey

        // NestedWitnessPubKey represents a p2sh output which is itself a

        // nested p2wkh output.

        NestedWitnessPubKey

        // TaprootPubkey represents a p2tr key path spending address.

        TaprootPubkey

)

var (

        // DefaultPublicPassphrase is the default public passphrase used for the

        // wallet.

        DefaultPublicPassphrase = []byte("public")

        // DefaultPrivatePassphrase is the default private passphrase used for

        // the wallet.

        DefaultPrivatePassphrase = []byte("hello")

        // ErrDoubleSpend is returned from PublishTransaction in case the

        // tx being published is spending an output spent by a conflicting

        // transaction.

        ErrDoubleSpend = errors.New("transaction rejected: output already spent")

        // ErrNotMine is an error denoting that a WalletController instance is

        // unable to spend a specified output.

        ErrNotMine = errors.New("the passed output doesn't belong to the wallet")

        // ErrMempoolFee is returned from PublishTransaction in case the tx

        // being published is not accepted into mempool because the fee

        // requirements of the mempool backend are not met.

        ErrMempoolFee = errors.New("transaction rejected by the mempool " +

                "because of low fees")

)

// ErrNoOutputs is returned if we try to create a transaction with no outputs

// or send coins to a set of outputs that is empty.

var ErrNoOutputs = errors.New("no outputs")

// ErrInvalidMinconf is returned if we try to create a transaction with

// invalid minConfs value.

var ErrInvalidMinconf = errors.New("minimum number of confirmations must " +

        "be a non-negative number")

// AddressProperty contains wallet related information of an address.

type AddressProperty struct {

        // Address is the address of an account.

        Address string

        // Internal denotes if the address is a change address.

        Internal bool

        // Balance returns the total balance of an address.

        Balance btcutil.Amount

        // DerivationPath is the derivation path of the address.

        DerivationPath string

        // PublicKey is the public key of the address.

        PublicKey *btcec.PublicKey

}

// AccountIdentifier contains information to uniquely identify an account.

type AccountIdentifier struct {

        // Name is the name of the account.

        Name string

        // AddressType is the type of addresses supported by the account.

        AddressType AddressType

        // DerivationPath is the derivation path corresponding to the account

        // public key.

        DerivationPath string

}

// Utxo is an unspent output denoted by its outpoint, and output value of the

// original output.

type Utxo struct {

        AddressType   AddressType

        Value         btcutil.Amount

        Confirmations int64

        PkScript      []byte

        wire.OutPoint

        PrevTx *wire.MsgTx

}

// OutputDetail contains additional information on a destination address.

type OutputDetail struct {

        OutputType   txscript.ScriptClass

        Addresses    []btcutil.Address

        PkScript     []byte

        OutputIndex  int

        Value        btcutil.Amount

        IsOurAddress bool

}

// PreviousOutPoint contains information about the previous outpoint.

type PreviousOutPoint struct {

        // OutPoint is the transaction out point in the format txid:n.

        OutPoint string

        // IsOurOutput denotes if the previous output is controlled by the

        // internal wallet. The flag will only detect p2wkh, np2wkh and p2tr

        // inputs as its own.

        IsOurOutput bool

}

// TransactionDetail describes a transaction with either inputs which belong to

// the wallet, or has outputs that pay to the wallet.

type TransactionDetail struct {

        // Hash is the transaction hash of the transaction.

        Hash chainhash.Hash

        // Value is the net value of this transaction (in satoshis) from the

        // PoV of the wallet. If this transaction purely spends from the

        // wallet's funds, then this value will be negative. Similarly, if this

        // transaction credits the wallet, then this value will be positive.

        Value btcutil.Amount

        // NumConfirmations is the number of confirmations this transaction

        // has. If the transaction is unconfirmed, then this value will be

        // zero.

        NumConfirmations int32

        // BlockHeight is the hash of the block which includes this

        // transaction. Unconfirmed transactions will have a nil value for this

        // field.

        BlockHash *chainhash.Hash

        // BlockHeight is the height of the block including this transaction.

        // Unconfirmed transaction will show a height of zero.

        BlockHeight int32

        // Timestamp is the unix timestamp of the block including this

        // transaction. If the transaction is unconfirmed, then this will be a

        // timestamp of txn creation.

        Timestamp int64

        // TotalFees is the total fee in satoshis paid by this transaction.

        TotalFees int64

        // OutputDetails contains output data for each destination address, such

        // as the output script and amount.

        OutputDetails []OutputDetail

        // RawTx returns the raw serialized transaction.

        RawTx []byte

        // Label is an optional transaction label.

        Label string

        // PreviousOutpoints are the inputs for a transaction.

        PreviousOutpoints []PreviousOutPoint

}

// TransactionSubscription is an interface which describes an object capable of

// receiving notifications of new transaction related to the underlying wallet.

// TODO(roasbeef): add balance updates?

type TransactionSubscription interface {

        // ConfirmedTransactions returns a channel which will be sent on as new

        // relevant transactions are confirmed.

        ConfirmedTransactions() chan *TransactionDetail

        // UnconfirmedTransactions returns a channel which will be sent on as

        // new relevant transactions are seen within the network.

        UnconfirmedTransactions() chan *TransactionDetail

        // Cancel finalizes the subscription, cleaning up any resources

        // allocated.

        Cancel()

}

// WalletController defines an abstract interface for controlling a local Pure

// Go wallet, a local or remote wallet via an RPC mechanism, or possibly even

// a daemon assisted hardware wallet. This interface serves the purpose of

// allowing LightningWallet to be seamlessly compatible with several wallets

// such as: uspv, btcwallet, Bitcoin Core, Electrum, etc. This interface then

// serves as a "base wallet", with Lightning Network awareness taking place at

// a "higher" level of abstraction. Essentially, an overlay wallet.

// Implementors of this interface must closely adhere to the documented

// behavior of all interface methods in order to ensure identical behavior

// across all concrete implementations.

type WalletController interface {

        // FetchOutpointInfo queries for the WalletController's knowledge of

        // the passed outpoint. If the base wallet determines this output is

        // under its control, then the original txout should be returned.

        // Otherwise, a non-nil error value of ErrNotMine should be returned

        // instead.

        FetchOutpointInfo(prevOut *wire.OutPoint) (*Utxo, error)

        // FetchDerivationInfo queries for the wallet's knowledge of the passed

        // pkScript and constructs the derivation info and returns it.

        FetchDerivationInfo(pkScript []byte) (*psbt.Bip32Derivation, error)

        // ScriptForOutput returns the address, witness program and redeem

        // script for a given UTXO. An error is returned if the UTXO does not

        // belong to our wallet or it is not a managed pubKey address.

        ScriptForOutput(output *wire.TxOut) (waddrmgr.ManagedPubKeyAddress,

                []byte, []byte, error)

        // ConfirmedBalance returns the sum of all the wallet's unspent outputs

        // that have at least confs confirmations. If confs is set to zero,

        // then all unspent outputs, including those currently in the mempool

        // will be included in the final sum. The account parameter serves as a

        // filter to retrieve the balance for a specific account. When empty,

        // the confirmed balance of all wallet accounts is returned.

        //

        // NOTE: Only witness outputs should be included in the computation of

        // the total spendable balance of the wallet. We require this as only

        // witness inputs can be used for funding channels.

        ConfirmedBalance(confs int32, accountFilter string) (btcutil.Amount,

                error)

        // NewAddress returns the next external or internal address for the

        // wallet dictated by the value of the `change` parameter. If change is

        // true, then an internal address should be used, otherwise an external

        // address should be returned. The type of address returned is dictated

        // by the wallet's capabilities, and may be of type: p2sh, p2wkh,

        // p2wsh, etc. The account parameter must be non-empty as it determines

        // which account the address should be generated from.

        NewAddress(addrType AddressType, change bool,

                account string) (btcutil.Address, error)

        // LastUnusedAddress returns the last *unused* address known by the

        // wallet. An address is unused if it hasn't received any payments.

        // This can be useful in UIs in order to continually show the

        // "freshest" address without having to worry about "address inflation"

        // caused by continual refreshing. Similar to NewAddress it can derive

        // a specified address type. By default, this is a non-change address.

        // The account parameter must be non-empty as it determines which

        // account the address should be generated from.

        LastUnusedAddress(addrType AddressType,

                account string) (btcutil.Address, error)

        // IsOurAddress checks if the passed address belongs to this wallet

        IsOurAddress(a btcutil.Address) bool

        // AddressInfo returns the information about an address, if it's known

        // to this wallet.

        AddressInfo(a btcutil.Address) (waddrmgr.ManagedAddress, error)

        // ListAccounts retrieves all accounts belonging to the wallet by

        // default. A name and key scope filter can be provided to filter

        // through all of the wallet accounts and return only those matching.

        ListAccounts(string, *waddrmgr.KeyScope) ([]*waddrmgr.AccountProperties,

                error)

        // RequiredReserve returns the minimum amount of satoshis that should be

        // kept in the wallet in order to fee bump anchor channels if necessary.

        // The value scales with the number of public anchor channels but is

        // capped at a maximum.

        RequiredReserve(uint32) btcutil.Amount

        // ListAddresses retrieves all the addresses along with their balance. An

        // account name filter can be provided to filter through all of the

        // wallet accounts and return the addresses of only those matching.

        ListAddresses(string, bool) (AccountAddressMap, error)

        // ImportAccount imports an account backed by an account extended public

        // key. The master key fingerprint denotes the fingerprint of the root

        // key corresponding to the account public key (also known as the key

        // with derivation path m/). This may be required by some hardware

        // wallets for proper identification and signing.

        //

        // The address type can usually be inferred from the key's version, but

        // may be required for certain keys to map them into the proper scope.

        //

        // For BIP-0044 keys, an address type must be specified as we intend to

        // not support importing BIP-0044 keys into the wallet using the legacy

        // pay-to-pubkey-hash (P2PKH) scheme. A nested witness address type will

        // force the standard BIP-0049 derivation scheme, while a witness

        // address type will force the standard BIP-0084 derivation scheme.

        //

        // For BIP-0049 keys, an address type must also be specified to make a

        // distinction between the standard BIP-0049 address schema (nested

        // witness pubkeys everywhere) and our own BIP-0049Plus address schema

        // (nested pubkeys externally, witness pubkeys internally).

        ImportAccount(name string, accountPubKey *hdkeychain.ExtendedKey,

                masterKeyFingerprint uint32, addrType *waddrmgr.AddressType,

                dryRun bool) (*waddrmgr.AccountProperties, []btcutil.Address,

                []btcutil.Address, error)

        // ImportPublicKey imports a single derived public key into the wallet.

        // The address type can usually be inferred from the key's version, but

        // in the case of legacy versions (xpub, tpub), an address type must be

        // specified as we intend to not support importing BIP-44 keys into the

        // wallet using the legacy pay-to-pubkey-hash (P2PKH) scheme.

        ImportPublicKey(pubKey *btcec.PublicKey,

                addrType waddrmgr.AddressType) error

        // ImportTaprootScript imports a user-provided taproot script into the

        // wallet. The imported script will act as a pay-to-taproot address.

        //

        // NOTE: Taproot keys imported through this RPC currently _cannot_ be

        // used for funding PSBTs. Only tracking the balance and UTXOs is

        // currently supported.

        ImportTaprootScript(scope waddrmgr.KeyScope,

                tapscript *waddrmgr.Tapscript) (waddrmgr.ManagedAddress, error)

        // SendOutputs funds, signs, and broadcasts a Bitcoin transaction paying

        // out to the specified outputs. In the case the wallet has insufficient

        // funds, or the outputs are non-standard, an error should be returned.

        // This method also takes the target fee expressed in sat/kw that should

        // be used when crafting the transaction.

        //

        // NOTE: This method requires the global coin selection lock to be held.

        SendOutputs(inputs fn.Set[wire.OutPoint], outputs []*wire.TxOut,

                feeRate chainfee.SatPerKWeight, minConfs int32, label string,

                strategy base.CoinSelectionStrategy) (*wire.MsgTx, error)

        // CreateSimpleTx creates a Bitcoin transaction paying to the specified

        // outputs. The transaction is not broadcasted to the network. In the

        // case the wallet has insufficient funds, or the outputs are

        // non-standard, an error should be returned. This method also takes

        // the target fee expressed in sat/kw that should be used when crafting

        // the transaction.

        //

        // NOTE: The dryRun argument can be set true to create a tx that

        // doesn't alter the database. A tx created with this set to true

        // SHOULD NOT be broadcasted.

        //

        // NOTE: This method requires the global coin selection lock to be held.

        CreateSimpleTx(inputs fn.Set[wire.OutPoint], outputs []*wire.TxOut,

                feeRate chainfee.SatPerKWeight, minConfs int32,

                strategy base.CoinSelectionStrategy, dryRun bool) (

                *txauthor.AuthoredTx, error)

        // GetTransactionDetails returns a detailed description of a transaction

        // given its transaction hash.

        GetTransactionDetails(txHash *chainhash.Hash) (

                *TransactionDetail, error)

        // ListUnspentWitness returns all unspent outputs which are version 0

        // witness programs. The 'minConfs' and 'maxConfs' parameters

        // indicate the minimum and maximum number of confirmations an output

        // needs in order to be returned by this method. Passing -1 as

        // 'minConfs' indicates that even unconfirmed outputs should be

        // returned. Using MaxInt32 as 'maxConfs' implies returning all

        // outputs with at least 'minConfs'. The account parameter serves as

        // a filter to retrieve the unspent outputs for a specific account.

        // When empty, the unspent outputs of all wallet accounts are returned.

        //

        // NOTE: This method requires the global coin selection lock to be held.

        ListUnspentWitness(minConfs, maxConfs int32,

                accountFilter string) ([]*Utxo, error)

        // ListTransactionDetails returns a list of all transactions which are

        // relevant to the wallet over [startHeight;endHeight]. If start height

        // is greater than end height, the transactions will be retrieved in

        // reverse order. To include unconfirmed transactions, endHeight should

        // be set to the special value -1. This will return transactions from

        // the tip of the chain until the start height (inclusive) and

        // unconfirmed transactions. The account parameter serves as a filter to

        // retrieve the transactions relevant to a specific account. When

        // empty, transactions of all wallet accounts are returned.

        ListTransactionDetails(startHeight, endHeight int32,

                accountFilter string) ([]*TransactionDetail, error)

        // LeaseOutput locks an output to the given ID, preventing it from being

        // available for any future coin selection attempts. The absolute time

        // of the lock's expiration is returned. The expiration of the lock can

        // be extended by successive invocations of this call. Outputs can be

        // unlocked before their expiration through `ReleaseOutput`.

        //

        // If the output is not known, wtxmgr.ErrUnknownOutput is returned. If

        // the output has already been locked to a different ID, then

        // wtxmgr.ErrOutputAlreadyLocked is returned.

        //

        // NOTE: This method requires the global coin selection lock to be held.

        LeaseOutput(id wtxmgr.LockID, op wire.OutPoint,

                duration time.Duration) (time.Time, error)

        // ReleaseOutput unlocks an output, allowing it to be available for coin

        // selection if it remains unspent. The ID should match the one used to

        // originally lock the output.

        //

        // NOTE: This method requires the global coin selection lock to be held.

        ReleaseOutput(id wtxmgr.LockID, op wire.OutPoint) error

        // ListLeasedOutputs returns a list of all currently locked outputs.

        ListLeasedOutputs() ([]*base.ListLeasedOutputResult, error)

        // PublishTransaction performs cursory validation (dust checks, etc),

        // then finally broadcasts the passed transaction to the Bitcoin network.

        // If the transaction is rejected because it is conflicting with an

        // already known transaction, ErrDoubleSpend is returned. If the

        // transaction is already known (published already), no error will be

        // returned. Other error returned depends on the currently active chain

        // backend. It takes an optional label which will save a label with the

        // published transaction.

        PublishTransaction(tx *wire.MsgTx, label string) error

        // LabelTransaction adds a label to a transaction. If the tx already

        // has a label, this call will fail unless the overwrite parameter

        // is set. Labels must not be empty, and they are limited to 500 chars.

        LabelTransaction(hash chainhash.Hash, label string, overwrite bool) error

        // FetchTx attempts to fetch a transaction in the wallet's database

        // identified by the passed transaction hash. If the transaction can't

        // be found, then a nil pointer is returned.

        FetchTx(chainhash.Hash) (*wire.MsgTx, error)

        // RemoveDescendants attempts to remove any transaction from the

        // wallet's tx store (that may be unconfirmed) that spends outputs

        // created by the passed transaction. This remove propagates

        // recursively down the chain of descendent transactions.

        RemoveDescendants(*wire.MsgTx) error

        // FundPsbt creates a fully populated PSBT packet that contains enough

        // inputs to fund the outputs specified in the passed in packet with the

        // specified fee rate. If there is change left, a change output from the

        // internal wallet is added and the index of the change output is

        // returned. Otherwise no additional output is created and the index -1

        // is returned. If no custom change scope is specified, the BIP0084 will

        // be used for default accounts and single imported public keys. For

        // custom account, no key scope should be provided as the coin selection

        // key scope will always be used to generate the change address.

        //

        // NOTE: If the packet doesn't contain any inputs, coin selection is

        // performed automatically. The account parameter must be non-empty as

        // it determines which set of coins are eligible for coin selection. If

        // the packet does contain any inputs, it is assumed that full coin

        // selection happened externally and no additional inputs are added. If

        // the specified inputs aren't enough to fund the outputs with the given

        // fee rate, an error is returned. No lock lease is acquired for any of

        // the selected/validated inputs. It is in the caller's responsibility

        // to lock the inputs before handing them out.

        FundPsbt(packet *psbt.Packet, minConfs int32,

                feeRate chainfee.SatPerKWeight, account string,

                changeScope *waddrmgr.KeyScope,

                strategy base.CoinSelectionStrategy,

                allowUtxo func(wtxmgr.Credit) bool) (int32, error)

        // SignPsbt expects a partial transaction with all inputs and outputs

        // fully declared and tries to sign all unsigned inputs that have all

        // required fields (UTXO information, BIP32 derivation information,

        // witness or sig scripts) set.

        // If no error is returned, the PSBT is ready to be given to the next

        // signer or to be finalized if lnd was the last signer.

        //

        // NOTE: This method only signs inputs (and only those it can sign), it

        // does not perform any other tasks (such as coin selection, UTXO

        // locking or input/output/fee value validation, PSBT finalization). Any

        // input that is incomplete will be skipped.

        SignPsbt(packet *psbt.Packet) ([]uint32, error)

        // FinalizePsbt expects a partial transaction with all inputs and

        // outputs fully declared and tries to sign all inputs that belong to

        // the specified account. Lnd must be the last signer of the

        // transaction. That means, if there are any unsigned non-witness inputs

        // or inputs without UTXO information attached or inputs without witness

        // data that do not belong to lnd's wallet, this method will fail. If no

        // error is returned, the PSBT is ready to be extracted and the final TX

        // within to be broadcast.

        //

        // NOTE: This method does NOT publish the transaction after it's been

        // finalized successfully.

        FinalizePsbt(packet *psbt.Packet, account string) error

        // DecorateInputs fetches the UTXO information of all inputs it can

        // identify and adds the required information to the package's inputs.

        // The failOnUnknown boolean controls whether the method should return

        // an error if it cannot identify an input or if it should just skip it.

        DecorateInputs(packet *psbt.Packet, failOnUnknown bool) error

        // SubscribeTransactions returns a TransactionSubscription client which

        // is capable of receiving async notifications as new transactions

        // related to the wallet are seen within the network, or found in

        // blocks.

        //

        // NOTE: a non-nil error should be returned if notifications aren't

        // supported.

        //

        // TODO(roasbeef): make distinct interface?

        SubscribeTransactions() (TransactionSubscription, error)

        // IsSynced returns a boolean indicating if from the PoV of the wallet,

        // it has fully synced to the current best block in the main chain.

        // It also returns an int64 indicating the timestamp of the best block

        // known to the wallet, expressed in Unix epoch time

        IsSynced() (bool, int64, error)

        // GetRecoveryInfo returns a boolean indicating whether the wallet is

        // started in recovery mode. It also returns a float64 indicating the

        // recovery progress made so far.

        GetRecoveryInfo() (bool, float64, error)

        // Start initializes the wallet, making any necessary connections,

        // starting up required goroutines etc.

        Start() error

        // Stop signals the wallet for shutdown. Shutdown may entail closing

        // any active sockets, database handles, stopping goroutines, etc.

        Stop() error

        // BackEnd returns a name for the wallet's backing chain service,

        // which could be e.g. btcd, bitcoind, neutrino, or another consensus

        // service.

        BackEnd() string

        // CheckMempoolAcceptance checks whether a transaction follows mempool

        // policies and returns an error if it cannot be accepted into the

        // mempool.

        CheckMempoolAcceptance(tx *wire.MsgTx) error

}

// BlockChainIO is a dedicated source which will be used to obtain queries

// related to the current state of the blockchain. The data returned by each of

// the defined methods within this interface should always return the most up

// to date data possible.

//

// TODO(roasbeef): move to diff package perhaps?

// TODO(roasbeef): move publish txn here?

type BlockChainIO interface {

        // GetBestBlock returns the current height and block hash of the valid

        // most-work chain the implementation is aware of.

        GetBestBlock() (*chainhash.Hash, int32, error)

        // GetUtxo attempts to return the passed outpoint if it's still a

        // member of the utxo set. The passed height hint should be the "birth

        // height" of the passed outpoint. The script passed should be the

        // script that the outpoint creates. In the case that the output is in

        // the UTXO set, then the output corresponding to that output is

        // returned.  Otherwise, a non-nil error will be returned.

        // As for some backends this call can initiate a rescan, the passed

        // cancel channel can be closed to abort the call.

        GetUtxo(op *wire.OutPoint, pkScript []byte, heightHint uint32,

                cancel <-chan struct{}) (*wire.TxOut, error)

        // GetBlockHash returns the hash of the block in the best blockchain

        // at the given height.

        GetBlockHash(blockHeight int64) (*chainhash.Hash, error)

        // GetBlock returns the block in the main chain identified by the given

        // hash.

        GetBlock(blockHash *chainhash.Hash) (*wire.MsgBlock, error)

        // GetBlockHeader returns the block header for the given block hash.

        GetBlockHeader(blockHash *chainhash.Hash) (*wire.BlockHeader, error)

}

// MessageSigner represents an abstract object capable of signing arbitrary

// messages. The capabilities of this interface are used to sign announcements

// to the network, or just arbitrary messages that leverage the wallet's keys

// to attest to some message.

type MessageSigner interface {

        // SignMessage attempts to sign a target message with the private key

        // described in the key locator. If the target private key is unable to

        // be found, then an error will be returned. The actual digest signed is

        // the single or double SHA-256 of the passed message.

        SignMessage(keyLoc keychain.KeyLocator, msg []byte,

                doubleHash bool) (*ecdsa.Signature, error)

}

// WalletDriver represents a "driver" for a particular concrete

// WalletController implementation. A driver is identified by a globally unique

// string identifier along with a 'New()' method which is responsible for

// initializing a particular WalletController concrete implementation.

type WalletDriver struct {

        // WalletType is a string which uniquely identifies the

        // WalletController that this driver, drives.

        WalletType string

        // New creates a new instance of a concrete WalletController

        // implementation given a variadic set up arguments. The function takes

        // a variadic number of interface parameters in order to provide

        // initialization flexibility, thereby accommodating several potential

        // WalletController implementations.

// RegisteredWallets returns a slice of all currently registered notifiers.

//

// NOTE: This function is safe for concurrent access.

func RegisteredWallets() []*WalletDriver {

        for _, wallet := range wallets {

}

// RegisterWallet registers a WalletDriver which is capable of driving a

// NOTE: This function is safe for concurrent access.

                return fmt.Errorf("wallet already registered")

//

// NOTE: This function is safe for concurrent access.

func SupportedWallets() []string {

        registerMtx.Lock()

        defer registerMtx.Unlock()

        supportedWallets := make([]string, 0, len(wallets))

        for walletName := range wallets {

                supportedWallets = append(supportedWallets, walletName)

        }

        return supportedWallets

}

// FetchFundingTxWrapper is a wrapper around FetchFundingTx, except that it will

// exit when the supplied quit channel is closed.

func FetchFundingTxWrapper(chain BlockChainIO, chanID *lnwire.ShortChannelID,

        quit chan struct{}) (*wire.MsgTx, error) {

        txChan := make(chan *wire.MsgTx, 1)

        errChan := make(chan error, 1)

        go func() {

                tx, err := FetchFundingTx(chain, chanID)

                if err != nil {

                        errChan <- err

                        return

                }

                txChan <- tx

        }()

        case <-quit:

                        "lnwallet.FetchFundingTxWrapper has been closed")

        }

}

// FetchFundingTx uses the given BlockChainIO to fetch and return the funding

// transaction identified by the passed short channel ID.

//

        blockNum := int64(chanID.BlockHeight)

        }

        fundingBlock, err := chain.GetBlock(blockHash)

        if err != nil {

                return nil, err

        }

                        chanID.TxIndex, numTxns-1, chanID)

        return fundingBlock.Transactions[chanID.TxIndex].Copy(), nil

}

// FetchPKScriptWithQuit fetches the output script for the given SCID and exits

                ID: *chanID,

        output, _, err := outputLocator.Locate(tx)