lnd.xprv/lnwallet/interface.go
Olaoluwa Osuntokun 2eb1936cce
lnwallet: extend the WalletController with a new txn pub/sub client
This commit adds a new simple interface related to the WalletController
which allows for subscribing to new notifications as transactions
relevant to the wallet are seen on at the network and/or mined. The
TransactionSubscription interface will prove useful for building higher
level UI’s on-top of the daemon which update the presentation layer in
response to received notifications.
2016-10-15 14:07:24 -07:00

335 lines
13 KiB
Go

package lnwallet
import (
"errors"
"fmt"
"sync"
"github.com/roasbeef/btcd/btcec"
"github.com/roasbeef/btcd/txscript"
"github.com/roasbeef/btcd/wire"
"github.com/roasbeef/btcutil"
)
// ErrNotMine is an error denoting that a WalletController instance is unable
// to spend a specifid output.
var ErrNotMine = errors.New("the passed output doesn't belong to the wallet")
// AddressType is a enum-like type which denotes the possible address types
// WalletController supports.
type AddressType uint8
const (
// WitnessPubKey represents a p2wkh address.
WitnessPubKey AddressType = iota
// NestedWitnessPubKey represents a p2sh output which is itself a
// nested p2wkh output.
NestedWitnessPubKey
// PublicKey represents a regular p2pkh output.
PubKeyHash
)
// Utxo is an unspent output denoted by its outpoint, and output value of the
// original output.
type Utxo struct {
Value btcutil.Amount
wire.OutPoint
}
// 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 wire.ShaHash
// 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 *wire.ShaHash
// 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
}
// 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 {
// 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.
FetchInputInfo(prevOut *wire.OutPoint) (*wire.TxOut, 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.
ConfirmedBalance(confs int32, witness bool) (btcutil.Amount, error)
// 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 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, p2pkh,
// p2wkh, p2wsh, etc.
NewAddress(addrType AddressType, change bool) (btcutil.Address, error)
// GetPrivKey retrives the underlying private key associated with the
// passed address. If the wallet is unable to locate this private key
// due to the address not being under control of the wallet, then an
// error should be returned.
GetPrivKey(a btcutil.Address) (*btcec.PrivateKey, error)
// NewRawKey returns a raw private key controlled by the wallet. These
// keys are used for the 2-of-2 multi-sig outputs for funding
// transactions, as well as the pub key used for commitment transactions.
NewRawKey() (*btcec.PublicKey, error)
// FetchRootKey returns a root key which will be used by the
// LightningWallet to deterministically generate secrets. The private
// key returned by this method should remain constant in-between
// WalletController restarts.
FetchRootKey() (*btcec.PrivateKey, 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, and error
// should be returned.
SendOutputs(outputs []*wire.TxOut) (*wire.ShaHash, error)
// ListUnspentWitness returns all unspent outputs which are version 0
// witness programs. The 'confirms' parameter indicates the minimum
// number of confirmations an output needs in order to be returned by
// this method. Passing -1 as 'confirms' indicates that even
// unconfirmed outputs should be returned.
ListUnspentWitness(confirms int32) ([]*Utxo, error)
// ListTransactionDetails returns a list of all transactions which are
// relevant to the wallet.
ListTransactionDetails() ([]*TransactionDetail, error)
// 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.
LockOutpoint(o wire.OutPoint)
// UnlockOutpoint unlocks an previously locked output, marking it
// eligible for coin seleciton.
UnlockOutpoint(o wire.OutPoint)
// PublishTransaction performs cursory validation (dust checks, etc),
// then finally broadcasts the passed transaction to the Bitcoin network.
PublishTransaction(tx *wire.MsgTx) 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 shuold be returned if notifications aren't
// supported.
//
// TODO(roasbeef): make distinct interface?
SubscribeTransactions() (TransactionSubscription, error)
// Start initializes the wallet, making any neccessary 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
}
// 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 {
// GetCurrentHeight returns the current height of the valid most-work
// chain the implementation is aware of.
GetCurrentHeight() (int32, error)
// GetTxOut returns the original output referenced by the passed
// outpoint.
GetUtxo(txid *wire.ShaHash, index uint32) (*wire.TxOut, error)
// GetTransaction returns the full transaction identified by the passed
// transaction ID.
GetTransaction(txid *wire.ShaHash) (*wire.MsgTx, error)
}
// SignDescriptor houses the necessary information required to succesfully sign
// a given output. This struct is used by the Signer interface in order to gain
// access to critial data needed to generate a valid signature.
type SignDescriptor struct {
// Pubkey is the public key to which the signature should be generated
// over. The Signer should then generate a signature with the private
// key corresponding to this public key.
PubKey *btcec.PublicKey
// RedeemScript is the full script required to properly redeem the
// output. This field will only be populated if a p2wsh or a p2sh
// output is being signed.
RedeemScript []byte
// Output is the target output which should be signed. The PkScript and
// Value fields within the output should be properly populated,
// otherwise an invalid signature may be generated.
Output *wire.TxOut
// HashType is the target sighash type that should be used when
// generating the final sighash, and signature.
HashType txscript.SigHashType
// SigHashes is the pre-computed sighash midstate to be used when
// generating the final sighash for signing.
SigHashes *txscript.TxSigHashes
// InputIndex is the target input within the transaction that should be
// signed.
InputIndex int
}
// Signer represents an abstract object capable of generating raw signatures as
// well as full complete input scripts given a valid SignDescriptor and
// transaction. This interface fully abstracts away signing paving the way for
// Signer implementations such as hardware wallets, hardware tokens, HSM's, or
// simply a regular wallet.
type Signer interface {
// SignOutputRaw generates a signature for the passed transaction
// according to the data within the passed SignDescriptor.
//
// NOTE: The resulting signature should be void of a sighash byte.
SignOutputRaw(tx *wire.MsgTx, signDesc *SignDescriptor) ([]byte, error)
// ComputeInputScript generates a complete InputIndex for the passed
// transaction with the signature as defined within the passed
// SignDescriptor. This method should be capable of generating the
// proper input script for both regular p2wkh output and p2wkh outputs
// nested within a regualr p2sh output.
ComputeInputScript(tx *wire.MsgTx, signDesc *SignDescriptor) (*InputScript, error)
}
// WalletDriver represents a "driver" for a particular concrete
// WalletController implementation. A driver is indentified 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 identifes 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 varidaic number of interface paramters in order to provide
// initialization flexibility, thereby accomodating several potential
// WalletController implementations.
New func(args ...interface{}) (WalletController, error)
}
var (
wallets = make(map[string]*WalletDriver)
registerMtx sync.Mutex
)
// RegisteredWallets returns a slice of all currently registered notifiers.
//
// NOTE: This function is safe for concurrent access.
func RegisteredWallets() []*WalletDriver {
registerMtx.Lock()
defer registerMtx.Unlock()
registeredWallets := make([]*WalletDriver, 0, len(wallets))
for _, wallet := range wallets {
registeredWallets = append(registeredWallets, wallet)
}
return registeredWallets
}
// RegisterWallet registers a WalletDriver which is capable of driving a
// concrete WalletController interface. In the case that this driver has
// already been registered, an error is returned.
//
// NOTE: This function is safe for concurrent access.
func RegisterWallet(driver *WalletDriver) error {
registerMtx.Lock()
defer registerMtx.Unlock()
if _, ok := wallets[driver.WalletType]; ok {
return fmt.Errorf("wallet already registered")
}
wallets[driver.WalletType] = driver
return nil
}
// SupportedWallets returns a slice of strings that represents the walelt
// drivers that have been registered and are therefore supported.
//
// 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
}