lnwallet: add a BtcWallet implementation of WalletController

This commit adds the first concrete implementation of the
WalletController interface: BtcWallet. This implementation is simply a
series of wrapper functions are the base btcwallet struct.

Additionally, for ease of use both the BlockChain IO and Signer
interface are also implemented by BtcWallet. Finally a new WalletDriver
implementation has been implemented, and will be register by the init()
method within this new package.

lnwallet/btcwallet/blockchain.go

@@ -0,0 +1,55 @@
+package btcwallet
+
+import (
+	"encoding/hex"
+
+	"github.com/roasbeef/btcd/wire"
+)
+
+// GetCurrentHeight returns the current height of the known block within the
+// main chain.
+//
+// This method is a part of the lnwallet.BlockChainIO interface.
+func (b *BtcWallet) GetCurrentHeight() (int32, error) {
+	_, height, err := b.rpc.GetBestBlock()
+	if err != nil {
+		return 0, err
+	}
+
+	return height, nil
+}
+
+// GetTxOut returns the original output referenced by the passed outpoint.
+//
+// This method is a part of the lnwallet.BlockChainIO interface.
+func (b *BtcWallet) GetUtxo(txid *wire.ShaHash, index uint32) (*wire.TxOut, error) {
+	txout, err := b.rpc.GetTxOut(txid, index, false)
+	if err != nil {
+		return nil, err
+	}
+
+	pkScript, err := hex.DecodeString(txout.ScriptPubKey.Hex)
+	if err != nil {
+		return nil, err
+	}
+
+	return &wire.TxOut{
+		// Sadly, gettxout returns the output value in BTC
+		// instead of satoshis.
+		Value:    int64(txout.Value) * 1e8,
+		PkScript: pkScript,
+	}, nil
+}
+
+// GetTransaction returns the full transaction identified by the passed
+// transaction ID.
+//
+// This method is a part of the lnwallet.BlockChainIO interface.
+func (b *BtcWallet) GetTransaction(txid *wire.ShaHash) (*wire.MsgTx, error) {
+	tx, err := b.rpc.GetRawTransaction(txid)
+	if err != nil {
+		return nil, err
+	}
+
+	return tx.MsgTx(), nil
+}

lnwallet/btcwallet/btcwallet.go

@@ -0,0 +1,380 @@
+package btcwallet
+
+import (
+	"encoding/hex"
+	"fmt"
+	"math"
+	"sync"
+
+	"github.com/lightningnetwork/lnd/lnwallet"
+	"github.com/roasbeef/btcd/btcec"
+	"github.com/roasbeef/btcd/chaincfg"
+	"github.com/roasbeef/btcd/txscript"
+	"github.com/roasbeef/btcd/wire"
+	"github.com/roasbeef/btcutil"
+	"github.com/roasbeef/btcwallet/chain"
+	"github.com/roasbeef/btcwallet/waddrmgr"
+	base "github.com/roasbeef/btcwallet/wallet"
+	"github.com/roasbeef/btcwallet/walletdb"
+)
+
+const (
+	defaultAccount = uint32(waddrmgr.DefaultAccountNum)
+)
+
+var (
+	lnNamespace = []byte("ln")
+	rootKey     = []byte("ln-root")
+)
+
+// BtcWallet is an implementation of the lnwallet.WalletController interface
+// backed by an active instance of btcwallet. At the time of the writing of
+// this documentation, this implementation requires a full btcd node to
+// operate.
+type BtcWallet struct {
+	// wallet is an active instance of btcwallet.
+	wallet *base.Wallet
+
+	// rpc is an an active RPC connection to btcd full-node.
+	rpc *chain.RPCClient
+
+	// lnNamespace is a namespace within btcwallet's walletdb used to store
+	// persistent state required by the WalletController interface but not
+	// natively supported by btcwallet.
+	lnNamespace walletdb.Namespace
+
+	netParams *chaincfg.Params
+
+	// utxoCache is a cache used to speed up repeated calls to
+	// FetchInputInfo.
+	utxoCache map[wire.OutPoint]*wire.TxOut
+	cacheMtx  sync.RWMutex
+}
+
+// A compile time check to ensure that BtcWallet implements the
+// WalletController interface.
+var _ lnwallet.WalletController = (*BtcWallet)(nil)
+
+// New returns a new fully initialized instance of BtcWallet given a valid
+// confirguration struct.
+func New(cfg *Config) (*BtcWallet, error) {
+	// Ensure the wallet exists or create it when the create flag is set.
+	netDir := networkDir(cfg.DataDir, cfg.NetParams)
+
+	var pubPass []byte
+	if cfg.PublicPass == nil {
+		pubPass = defaultPubPassphrase
+	} else {
+		pubPass = cfg.PublicPass
+	}
+
+	loader := base.NewLoader(cfg.NetParams, netDir)
+	walletExists, err := loader.WalletExists()
+	if err != nil {
+		return nil, err
+	}
+
+	var wallet *base.Wallet
+	if !walletExists {
+		// Wallet has never been created, perform initial set up.
+		wallet, err = loader.CreateNewWallet(pubPass, cfg.PrivatePass,
+			cfg.HdSeed)
+		if err != nil {
+			return nil, err
+		}
+	} else {
+		// Wallet has been created and been initialized at this point, open it
+		// along with all the required DB namepsaces, and the DB itself.
+		wallet, err = loader.OpenExistingWallet(pubPass, false)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	if err := wallet.Manager.Unlock(cfg.PrivatePass); err != nil {
+		return nil, err
+	}
+
+	// Create a special websockets rpc client for btcd which will be used
+	// by the wallet for notifications, calls, etc.
+	rpcc, err := chain.NewRPCClient(cfg.NetParams, cfg.RpcHost,
+		cfg.RpcUser, cfg.RpcPass, cfg.CACert, false, 20)
+	if err != nil {
+		return nil, err
+	}
+
+	db := wallet.Database()
+	walletNamespace, err := db.Namespace(lnNamespace)
+	if err != nil {
+		return nil, err
+	}
+
+	return &BtcWallet{
+		wallet:      wallet,
+		rpc:         rpcc,
+		lnNamespace: walletNamespace,
+		netParams:   cfg.NetParams,
+		utxoCache:   make(map[wire.OutPoint]*wire.TxOut),
+	}, nil
+}
+
+// Start initializes the underlying rpc connection, the wallet itself, and
+// begins syncing to the current available blockchain state.
+//
+// This is a part of the WalletController interface.
+func (b *BtcWallet) Start() error {
+	// Establish an RPC connection in additino to starting the goroutines
+	// in the underlying wallet.
+	if err := b.rpc.Start(); err != nil {
+		return err
+	}
+
+	// Start the underlying btcwallet core.
+	b.wallet.Start()
+
+	// Pass the rpc client into the wallet so it can sync up to the
+	// current main chain.
+	b.wallet.SynchronizeRPC(b.rpc)
+
+	return nil
+}
+
+// Stop signals the wallet for shutdown. Shutdown may entail closing
+// any active sockets, database handles, stopping goroutines, etc.
+//
+// This is a part of the WalletController interface.
+func (b *BtcWallet) Stop() error {
+	b.wallet.Stop()
+
+	b.wallet.WaitForShutdown()
+
+	b.rpc.Shutdown()
+
+	return nil
+}
+
+// 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.
+//
+// This is a part of the WalletController interface.
+func (b *BtcWallet) ConfirmedBalance(confs int32, witness bool) (btcutil.Amount, error) {
+	var balance btcutil.Amount
+
+	if witness {
+		witnessOutputs, err := b.ListUnspentWitness(confs)
+		if err != nil {
+			return 0, err
+		}
+
+		for _, witnessOutput := range witnessOutputs {
+			balance += witnessOutput.Value
+		}
+	} else {
+		outputSum, err := b.wallet.CalculateBalance(confs)
+		if err != nil {
+			return 0, err
+		}
+
+		balance = outputSum
+	}
+
+	return balance, nil
+}
+
+// NewAddress returns the next external or internal address for the wallet
+// dicatated by the value of the `change` paramter. If change is true, then an
+// internal address will be returned, otherwise an external address should be
+// returned.
+//
+// This is a part of the WalletController interface.
+func (b *BtcWallet) NewAddress(t lnwallet.AddressType, change bool) (btcutil.Address, error) {
+	var addrType waddrmgr.AddressType
+
+	switch t {
+	case lnwallet.WitnessPubKey:
+		addrType = waddrmgr.WitnessPubKey
+	case lnwallet.NestedWitnessPubKey:
+		addrType = waddrmgr.NestedWitnessPubKey
+	case lnwallet.PubKeyHash:
+		addrType = waddrmgr.PubKeyHash
+	default:
+		return nil, fmt.Errorf("unknown address type")
+	}
+
+	if change {
+		return b.wallet.NewAddress(defaultAccount, addrType)
+	} else {
+		return b.wallet.NewChangeAddress(defaultAccount, addrType)
+	}
+}
+
+// GetPrivKey retrives the underlying private key associated with the passed
+// address. If the we're unable to locate the proper private key, then a
+// non-nil error will be returned.
+//
+// This is a part of the WalletController interface.
+func (b *BtcWallet) GetPrivKey(a btcutil.Address) (*btcec.PrivateKey, error) {
+	// Using the ID address, request the private key coresponding to the
+	// address from the wallet's address manager.
+	walletAddr, err := b.wallet.Manager.Address(a)
+	if err != nil {
+		return nil, err
+	}
+
+	return walletAddr.(waddrmgr.ManagedPubKeyAddress).PrivKey()
+}
+
+// NewRawKey retrieves the next key within our HD key-chain for use within as a
+// multi-sig key within the funding transaction, or within the commitment
+// transaction's outputs.
+//
+// This is a part of the WalletController interface.
+func (b *BtcWallet) NewRawKey() (*btcec.PublicKey, error) {
+	nextAddr, err := b.wallet.Manager.NextExternalAddresses(defaultAccount,
+		1, waddrmgr.WitnessPubKey)
+	if err != nil {
+		return nil, err
+	}
+
+	pkAddr := nextAddr[0].(waddrmgr.ManagedPubKeyAddress)
+
+	return pkAddr.PubKey(), nil
+}
+
+// FetchRootKey returns a root key which is meanted to be used as an initial
+// seed/salt to generate any Lightning specific secrets.
+//
+// This is a part of the WalletController interface.
+func (b *BtcWallet) FetchRootKey() (*btcec.PrivateKey, error) {
+	// Fetch the root address hash from the database, this is persisted
+	// locally within the database, then used to obtain the key from the
+	// wallet based on the address hash.
+	var rootAddrHash []byte
+	if err := b.lnNamespace.Update(func(tx walletdb.Tx) error {
+		rootBucket := tx.RootBucket()
+
+		rootAddrHash = rootBucket.Get(rootKey)
+		return nil
+	}); err != nil {
+		return nil, err
+	}
+
+	if rootAddrHash == nil {
+		// Otherwise, we need to generate a fresh address from the
+		// wallet, then stores it's hash160 within the database so we
+		// can look up the exact key later.
+		rootAddr, err := b.wallet.Manager.NextExternalAddresses(defaultAccount,
+			1, waddrmgr.WitnessPubKey)
+		if err != nil {
+			return nil, err
+		}
+
+		if err := b.lnNamespace.Update(func(tx walletdb.Tx) error {
+			rootBucket := tx.RootBucket()
+
+			rootAddrHash = rootAddr[0].Address().ScriptAddress()
+			if err := rootBucket.Put(rootKey, rootAddrHash); err != nil {
+				return err
+			}
+
+			return nil
+		}); err != nil {
+			return nil, err
+		}
+	}
+
+	// With the root address hash obtained, generate the corresponding
+	// address, then retrieve the managed address from the wallet which
+	// will allow us to obtain the private key.
+	rootAddr, err := btcutil.NewAddressWitnessPubKeyHash(rootAddrHash,
+		b.netParams)
+	if err != nil {
+		return nil, err
+	}
+	walletAddr, err := b.wallet.Manager.Address(rootAddr)
+	if err != nil {
+		return nil, err
+	}
+
+	return walletAddr.(waddrmgr.ManagedPubKeyAddress).PrivKey()
+}
+
+// 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, a non-nil error will be be returned.
+//
+// This is a part of the WalletController interface.
+func (b *BtcWallet) SendOutputs(outputs []*wire.TxOut) (*wire.ShaHash, error) {
+	return b.wallet.SendOutputs(outputs, defaultAccount, 1)
+}
+
+// LockOutpoint marks an outpoint as locked meaning it will no longer be deemed
+// as eligible for coin selection. Locking outputs are utilized in order to
+// avoid race conditions when selecting inputs for usage when funding a
+// channel.
+//
+// This is a part of the WalletController interface.
+func (b *BtcWallet) LockOutpoint(o wire.OutPoint) {
+	b.wallet.LockOutpoint(o)
+}
+
+// UnlockOutpoint unlocks an previously locked output, marking it eligible for
+// coin seleciton.
+//
+// This is a part of the WalletController interface.
+func (b *BtcWallet) UnlockOutpoint(o wire.OutPoint) {
+	b.wallet.UnlockOutpoint(o)
+}
+
+// ListUnspentWitness returns a slice of all the unspent outputs the wallet
+// controls which pay to witness programs either directly or indirectly.
+//
+// This is a part of the WalletController interface.
+func (b *BtcWallet) ListUnspentWitness(minConfs int32) ([]*lnwallet.Utxo, error) {
+	// First, grab all the unfiltered currently unspent outputs.
+	maxConfs := int32(math.MaxInt32)
+	unspentOutputs, err := b.wallet.ListUnspent(minConfs, maxConfs, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	// Next, we'll run through all the regular outputs, only saving those
+	// which are p2wkh outputs or a p2wsh output nested within a p2sh output.
+	witnessOutputs := make([]*lnwallet.Utxo, 0, len(unspentOutputs))
+	for _, output := range unspentOutputs {
+		pkScript, err := hex.DecodeString(output.ScriptPubKey)
+		if err != nil {
+			return nil, err
+		}
+
+		// TODO(roasbeef): this assumes all p2sh outputs returned by
+		// the wallet are nested p2sh...
+		if txscript.IsPayToWitnessPubKeyHash(pkScript) ||
+			txscript.IsPayToScriptHash(pkScript) {
+			txid, err := wire.NewShaHashFromStr(output.TxID)
+			if err != nil {
+				return nil, err
+			}
+
+			utxo := &lnwallet.Utxo{
+				Value: btcutil.Amount(output.Amount * 1e8),
+				OutPoint: wire.OutPoint{
+					Hash:  *txid,
+					Index: output.Vout,
+				},
+			}
+			witnessOutputs = append(witnessOutputs, utxo)
+		}
+
+	}
+
+	return witnessOutputs, nil
+}
+
+// PublishTransaction performs cursory validation (dust checks, etc), then
+// finally broadcasts the passed transaction to the Bitcoin network.
+func (b *BtcWallet) PublishTransaction(tx *wire.MsgTx) error {
+	return b.wallet.PublishTransaction(tx)
+}

lnwallet/btcwallet/config.go

@@ -0,0 +1,94 @@
+package btcwallet
+
+import (
+	"path/filepath"
+
+	"github.com/roasbeef/btcd/chaincfg"
+	"github.com/roasbeef/btcd/wire"
+	"github.com/roasbeef/btcutil"
+	_ "github.com/roasbeef/btcwallet/walletdb/bdb"
+)
+
+var (
+	lnwalletHomeDir = btcutil.AppDataDir("lnwallet", false)
+	defaultDataDir  = lnwalletHomeDir
+
+	defaultLogFilename = "lnwallet.log"
+	defaultLogDirname  = "logs"
+	defaultLogDir      = filepath.Join(lnwalletHomeDir, defaultLogDirname)
+
+	btcdHomeDir        = btcutil.AppDataDir("btcd", false)
+	btcdHomedirCAFile  = filepath.Join(btcdHomeDir, "rpc.cert")
+	defaultRPCKeyFile  = filepath.Join(lnwalletHomeDir, "rpc.key")
+	defaultRPCCertFile = filepath.Join(lnwalletHomeDir, "rpc.cert")
+
+	// defaultPubPassphrase is the default public wallet passphrase which is
+	// used when the user indicates they do not want additional protection
+	// provided by having all public data in the wallet encrypted by a
+	// passphrase only known to them.
+	defaultPubPassphrase = []byte("public")
+
+	walletDbName = "lnwallet.db"
+)
+
+// Config is a struct which houses configuration paramters which modify the
+// instance of BtcWallet generated by the New() function.
+type Config struct {
+	// DataDir is the name of the directory where the wallet's persistent
+	// state should be sotred.
+	DataDir string
+
+	// LogDir is the name of the directory which should be used to store
+	// generated log files.
+	LogDir string
+
+	// DebugLevel is a string representing the level of verbosity the
+	// logger should use.
+	DebugLevel string
+
+	// RpcHost is the host and port to use to reach the rpc sever.
+	RpcHost string // localhost:18334
+
+	// RpcUser is the username which should be used to authentiate with the
+	// rpc server.
+	RpcUser string
+
+	// RpcPass is the password which should be used to authenticate the
+	// connection with the RPC server.
+	RpcPass string
+
+	// RpcNoTLS denotes if a TLS connection should be attempted when
+	// connecting to the RPC server.
+	RpcNoTLS bool
+
+	// RPCCert directory where the TLS certificate of the RPC sever is
+	// stored. If the RpcNoTLS is false, then this value will be unused.
+	RPCCert string
+	RPCKey  string
+
+	// CACert is the raw RPC cert for btcd.
+	CACert []byte
+
+	PrivatePass []byte
+	PublicPass  []byte
+	HdSeed      []byte
+
+	NetParams *chaincfg.Params
+}
+
+// networkDir returns the directory name of a network directory to hold wallet
+// files.
+func networkDir(dataDir string, chainParams *chaincfg.Params) string {
+	netname := chainParams.Name
+
+	// For now, we must always name the testnet data directory as "testnet"
+	// and not "testnet3" or any other version, as the chaincfg testnet3
+	// paramaters will likely be switched to being named "testnet3" in the
+	// future.  This is done to future proof that change, and an upgrade
+	// plan to move the testnet3 data directory can be worked out later.
+	if chainParams.Net == wire.TestNet3 {
+		netname = "testnet"
+	}
+
+	return filepath.Join(dataDir, netname)
+}

lnwallet/btcwallet/driver.go

@@ -0,0 +1,45 @@
+package btcwallet
+
+import (
+	"fmt"
+
+	"github.com/lightningnetwork/lnd/lnwallet"
+)
+
+const (
+	walletType = "btcwallet"
+)
+
+// createNewWallet creates a new instance of BtcWallet given the proper list of
+// initialization parameters. This function is the factory function required to
+// properly create an instance of the lnwallet.WalletDriver struct for
+// BtcWallet.
+func createNewWallet(args ...interface{}) (lnwallet.WalletController, error) {
+	if len(args) != 1 {
+		return nil, fmt.Errorf("incorrect number of arguments to .New(...), "+
+			"expected 1, instead passed %v", len(args))
+	}
+
+	config, ok := args[0].(*Config)
+	if !ok {
+		return nil, fmt.Errorf("first argument to btcdnotifier.New is " +
+			"incorrect, expected a *btcrpcclient.ConnConfig")
+	}
+
+	return New(config)
+}
+
+// init registers a driver for the BtcWallet concrete implementation of the
+// lnwallet.WalletController interface.
+func init() {
+	// Register the driver.
+	driver := &lnwallet.WalletDriver{
+		WalletType: walletType,
+		New:        createNewWallet,
+	}
+
+	if err := lnwallet.RegisterWallet(driver); err != nil {
+		panic(fmt.Sprintf("failed to register wallet driver '%s': %v",
+			walletType, err))
+	}
+}

lnwallet/btcwallet/signer.go

@@ -0,0 +1,174 @@
+package btcwallet
+
+import (
+	"fmt"
+
+	"github.com/lightningnetwork/lnd/lnwallet"
+	"github.com/roasbeef/btcd/txscript"
+	"github.com/roasbeef/btcd/wire"
+	"github.com/roasbeef/btcutil"
+	"github.com/roasbeef/btcwallet/waddrmgr"
+)
+
+// FetchInputInfo 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.
+//
+// This is a part of the WalletController interface.
+func (b *BtcWallet) FetchInputInfo(prevOut *wire.OutPoint) (*wire.TxOut, error) {
+	var (
+		err    error
+		output *wire.TxOut
+	)
+
+	// First check to see if the output is already within the utxo cache.
+	// If so we can return directly saving usk a disk access.
+	b.cacheMtx.RLock()
+	if output, ok := b.utxoCache[*prevOut]; ok {
+		b.cacheMtx.RUnlock()
+		return output, nil
+	}
+	b.cacheMtx.RUnlock()
+
+	// Otherwse, we manually look up the output within the tx store.
+	txDetail, err := b.wallet.TxStore.TxDetails(&prevOut.Hash)
+	if err != nil {
+		return nil, err
+	} else if txDetail == nil {
+		return nil, lnwallet.ErrNotMine
+	}
+
+	output = txDetail.TxRecord.MsgTx.TxOut[prevOut.Index]
+
+	b.cacheMtx.Lock()
+	b.utxoCache[*prevOut] = output
+	b.cacheMtx.Unlock()
+
+	return output, nil
+}
+
+// fetchOutputKey attempts to fetch the managed address corresponding to the
+// passed output script. This function is used to look up the proper key which
+// should be used to sign a specified input.
+func (b *BtcWallet) fetchOutputAddr(script []byte) (waddrmgr.ManagedAddress, error) {
+	_, addrs, _, err := txscript.ExtractPkScriptAddrs(script, b.netParams)
+	if err != nil {
+		return nil, err
+	}
+
+	// If the case of a multi-sig output, several address may be extracted.
+	// Therefore, we simply select the key for the first address we know
+	// of.
+	for _, addr := range addrs {
+		wAddr, err := b.wallet.Manager.Address(addr)
+		if err == nil {
+			return wAddr, nil
+		}
+	}
+
+	// TODO(roasbeef): use the errors.wrap package
+	return nil, fmt.Errorf("address not found")
+}
+
+// SignOutputRaw generates a signature for the passed transaction according to
+// the data within the passed SignDescriptor.
+//
+// This is a part of the WalletController interface.
+func (b *BtcWallet) SignOutputRaw(tx *wire.MsgTx, signDesc *lnwallet.SignDescriptor) ([]byte, error) {
+	redeemScript := signDesc.RedeemScript
+	walletAddr, err := b.fetchOutputAddr(redeemScript)
+	if err != nil {
+		return nil, err
+	}
+
+	privKey, err := walletAddr.(waddrmgr.ManagedPubKeyAddress).PrivKey()
+	if err != nil {
+		return nil, err
+	}
+
+	amt := signDesc.Output.Value
+	sig, err := txscript.RawTxInWitnessSignature(tx, signDesc.SigHashes, 0,
+		amt, redeemScript, txscript.SigHashAll, privKey)
+	if err != nil {
+		return nil, err
+	}
+
+	// Chop off the sighash flag at the end of the signature.
+	return sig[:len(sig)-1], nil
+}
+
+// ComputeInputScript generates a complete InputIndex for the passed
+// transaction with the signature as defined within the passed SignDescriptor.
+// This method is capable of generating the proper input script for both
+// regular p2wkh output and p2wkh outputs nested within a regualr p2sh output.
+//
+// This is a part of the WalletController interface.
+func (b *BtcWallet) ComputeInputScript(tx *wire.MsgTx,
+	signDesc *lnwallet.SignDescriptor) (*lnwallet.InputScript, error) {
+
+	outputScript := signDesc.Output.PkScript
+	walletAddr, err := b.fetchOutputAddr(outputScript)
+	if err != nil {
+		return nil, nil
+	}
+
+	pka := walletAddr.(waddrmgr.ManagedPubKeyAddress)
+	privKey, err := pka.PrivKey()
+	if err != nil {
+		return nil, err
+	}
+
+	var witnessProgram []byte
+	inputScript := &lnwallet.InputScript{}
+
+	// If we're spending p2wkh output nested within a p2sh output, then
+	// we'll need to attach a sigScript in addition to witness data.
+	switch {
+	case pka.IsNestedWitness():
+		pubKey := privKey.PubKey()
+		pubKeyHash := btcutil.Hash160(pubKey.SerializeCompressed())
+
+		// Next, we'll generate a valid sigScript that'll allow us to
+		// spend the p2sh output. The sigScript will contain only a
+		// single push of the p2wkh witness program corresponding to
+		// the matching public key of this address.
+		p2wkhAddr, err := btcutil.NewAddressWitnessPubKeyHash(pubKeyHash,
+			b.netParams)
+		if err != nil {
+			return nil, err
+		}
+		witnessProgram, err = txscript.PayToAddrScript(p2wkhAddr)
+		if err != nil {
+			return nil, err
+		}
+
+		bldr := txscript.NewScriptBuilder()
+		bldr.AddData(witnessProgram)
+		sigScript, err := bldr.Script()
+		if err != nil {
+			return nil, err
+		}
+
+		inputScript.ScriptSig = sigScript
+	// Otherwise, this is a regular p2wkh output, so we include the
+	// witness program itself as the subscript to generate the proper
+	// sighash digest. As part of the new sighash digest algorithm, the
+	// p2wkh witness program will be expanded into a regular p2kh
+	// script.
+	default:
+		witnessProgram = outputScript
+	}
+
+	// Generate a valid witness stack for the input.
+	witnessScript, err := txscript.WitnessScript(tx, signDesc.SigHashes,
+		signDesc.InputIndex, signDesc.Output.Value, witnessProgram,
+		txscript.SigHashAll, privKey, true)
+	if err != nil {
+		return nil, err
+	}
+
+	inputScript.Witness = witnessScript
+
+	return inputScript, nil
+}

lnwallet/config.go

@@ -1,60 +1,15 @@
 package lnwallet
 
-import (
-	"path/filepath"
-
-	"github.com/roasbeef/btcd/chaincfg"
-	"github.com/roasbeef/btcutil"
-)
-
-var (
-	// TODO(roasbeef): lnwallet config file
-	lnwalletHomeDir = btcutil.AppDataDir("lnwallet", false)
-	defaultDataDir  = lnwalletHomeDir
-
-	defaultLogFilename = "lnwallet.log"
-	defaultLogDirname  = "logs"
-	defaultLogDir      = filepath.Join(lnwalletHomeDir, defaultLogDirname)
-
-	btcdHomeDir        = btcutil.AppDataDir("btcd", false)
-	btcdHomedirCAFile  = filepath.Join(btcdHomeDir, "rpc.cert")
-	defaultRPCKeyFile  = filepath.Join(lnwalletHomeDir, "rpc.key")
-	defaultRPCCertFile = filepath.Join(lnwalletHomeDir, "rpc.cert")
-
-	// defaultPubPassphrase is the default public wallet passphrase which is
-	// used when the user indicates they do not want additional protection
-	// provided by having all public data in the wallet encrypted by a
-	// passphrase only known to them.
-	defaultPubPassphrase = []byte("public")
-
-	walletDbName = "lnwallet.db"
-)
-
-// Config...
+// Config..
 type Config struct {
-	DataDir string
-	LogDir  string
-
-	DebugLevel string
-
-	RpcHost  string // localhost:18334
-	RpcUser  string
-	RpcPass  string
-	RpcNoTLS bool
-
-	RPCCert string
-	RPCKey  string
-
-	CACert []byte
-
-	PrivatePass []byte
-	PublicPass  []byte
-	HdSeed      []byte
-
-	// Which bitcoin network are we using?
-	NetParams *chaincfg.Params
-}
-
-// setDefaults...
-func setDefaults(confg *Config) {
+	// default csv time
+	// default cltv time
+	// default wait for funding time
+	// default wait for closure time
+	// min amount to accept channel
+	// min fee imformation
+	//  * or possibly interface to predict fees
+	// max htlcs in flight?
+	// possible secret derivation functions
+	//
 }