lnwallet: revamp interfaces, add BlockChainIO and Singer
This commit revamps the previous WalletController interface, edging it closer to a more complete version. Additionally, this commit also introduces two new interfaces: BlockchainIO, and Singer along with a new factor driver struct, the WalletDriver. This BlockChainIO abstracts read-only access to the blockchain, while the Singer interface abstracts the signing of inputs from the base wallet paving the way to hardware wallets, air-gapped signing, etc. Finally, in order to provide an easy method for selecting a particular concrete implementation of a WalletController interface, the concept of registering “WalletDriver”s has been introduced. A wallet driver is essentially the encapsulation of a factory function capable of create a new instance of a Wallet Controller.
This commit is contained in:
Olaoluwa Osuntokun
parent
a87ddeabdc
commit
5449ba2b34
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@ -1,11 +1,43 @@
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package lnwallet
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import (
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"errors"
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"fmt"
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"sync"
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"github.com/roasbeef/btcd/btcec"
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"github.com/roasbeef/btcd/txscript"
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"github.com/roasbeef/btcd/wire"
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"github.com/roasbeef/btcutil"
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)
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// ErrNotMine is an error denoting that a WalletController instance is unable
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// to spend a specifid output.
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var ErrNotMine = errors.New("the passed output doesn't belong to the wallet")
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// AddressType is a enum-like type which denotes the possible address types
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// WalletController supports.
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type AddressType uint8
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const (
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// WitnessPubKey represents a p2wkh address.
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WitnessPubKey AddressType = iota
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// NestedWitnessPubKey represents a p2sh output which is itself a
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// nested p2wkh output.
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NestedWitnessPubKey
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// PublicKey represents a regular p2pkh output.
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PubKeyHash
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)
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// Utxo is an unspent output denoted by its outpoint, and output value of the
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// original output.
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type Utxo struct {
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Value btcutil.Amount
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wire.OutPoint
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}
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// WalletController defines an abstract interface for controlling a local Pure
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// Go wallet, a local or remote wallet via an RPC mechanism, or possibly even
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// a daemon assisted hardware wallet. This interface serves the purpose of
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@ -17,82 +49,71 @@ import (
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// behavior of all interface methods in order to ensure identical behavior
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// across all concrete implementations.
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type WalletController interface {
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// FetchInputInfo queries for the WalletController's knowledge of the
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// passed outpoint. If the base wallet determines this output is under
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// its control, then the original txout should be returned. Otherwise,
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// a non-nil error value of ErrNotMine should be returned instead.
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FetchInputInfo(prevOut *wire.OutPoint) (*wire.TxOut, error)
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// ConfirmedBalance returns the sum of all the wallet's unspent outputs
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// that have at least confs confirmations. If confs is set to zero,
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// then all unspent outputs, including those currently in the mempool
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// will be included in the final sum.
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ConfirmedBalance(confs int32) btcutil.Amount
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ConfirmedBalance(confs int32, witness bool) (btcutil.Amount, error)
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// NewAddress returns the next external address for the wallet. The
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// type of address returned is dictated by the wallet's capabilities,
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// and may be of type: p2sh, p2pkh, p2wkh, p2wsh, etc.
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NewAddress(witness bool) (btcutil.Address, error)
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// NewChangeAddress returns a new change address for the wallet. If the
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// underlying wallet supports hd key chains, then this address should be
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// dervied from an internal branch.
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NewChangeAddress(witness bool) (btcutil.Address, error)
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// NewAddress returns the next external or internal address for the
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// wallet dicatated by the value of the `change` paramter. If change is
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// true, then an internal address should be used, otherwise an external
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// address should be returned. The type of address returned is dictated
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// by the wallet's capabilities, and may be of type: p2sh, p2pkh,
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// p2wkh, p2wsh, etc.
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NewAddress(addrType AddressType, change bool) (btcutil.Address, error)
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// GetPrivKey retrives the underlying private key associated with the
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// passed address. If the wallet is unable to locate this private key
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// due to the address not being under control of the wallet, then an
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// error should be returned.
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GetPrivKey(a *btcutil.Address) (*btcec.PrivateKey, error)
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// TODO(roasbeef): should instead take tadge's derivation scheme in
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GetPrivKey(a btcutil.Address) (*btcec.PrivateKey, error)
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// NewRawKey returns a raw private key controlled by the wallet. These
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// keys are used for the 2-of-2 multi-sig outputs for funding
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// transactions, as well as the pub key used for commitment transactions.
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// TODO(roasbeef): key pool due to cancelled reservations??
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NewRawKey() (*btcec.PrivateKey, error)
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// TODO(roasbeef): may be scrapped, see above TODO
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NewRawKey() (*btcec.PublicKey, error)
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// FetchIdentityKey returns a private key which will be utilized as the
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// wallet's Lightning Network identity for authentication purposes.
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// TODO(roasbeef): rotate identity key?
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FetchIdentityKey() (*btcec.PrivateKey, error)
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// FetchRootKey returns a root key which will be used by the
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// LightningWallet to deterministically generate secrets. The private
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// key returned by this method should remain constant in-between
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// WalletController restarts.
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FetchRootKey() (*btcec.PrivateKey, error)
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// FundTransaction creates a new unsigned transactions paying to the
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// passed outputs, possibly using the specified change address. The
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// includeFee parameter dictates if the wallet should also provide
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// enough the funds necessary to create an adequate fee or not.
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FundTransaction(outputs []*wire.TxOut, changeAddr btcutil.Address,
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includeFee bool) (*wire.MsgTx, error)
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// SignTransaction performs potentially a sparse, or full signing of
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// all inputs within the passed transaction that are spendable by the
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// wallet.
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SignTransaction(tx *wire.MsgTx) error
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// BroadcastTransaction performs cursory validation (dust checks, etc),
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// then finally broadcasts the passed transaction to the Bitcoin network.
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BroadcastTransaction(tx *wire.MsgTx) error
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// SendMany funds, signs, and broadcasts a Bitcoin transaction paying
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// out to the specified outputs. In the case the wallet has insufficient
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// funds, or the outputs are non-standard, and error should be returned.
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SendMany(outputs []*wire.TxOut) (*wire.ShaHash, error)
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// SendOutputs funds, signs, and broadcasts a Bitcoin transaction
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// paying out to the specified outputs. In the case the wallet has
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// insufficient funds, or the outputs are non-standard, and error
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// should be returned.
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SendOutputs(outputs []*wire.TxOut) (*wire.ShaHash, error)
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// ListUnspentWitness returns all unspent outputs which are version 0
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// witness programs. The 'confirms' parameter indicates the minimum
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// number of confirmations an output needs in order to be returned by
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// this method. Passing -1 as 'confirms' indicates that even unconfirmed
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// outputs should be returned.
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ListUnspentWitness(confirms int32) ([]*wire.OutPoint, error)
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// this method. Passing -1 as 'confirms' indicates that even
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// unconfirmed outputs should be returned.
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ListUnspentWitness(confirms int32) ([]*Utxo, error)
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// LockOutpoint marks an outpoint as locked meaning it will no longer
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// be deemed as eligble for coin selection. Locking outputs are utilized
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// in order to avoid race conditions when selecting inputs for usage when
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// funding a channel.
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// be deemed as eligible for coin selection. Locking outputs are
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// utilized in order to avoid race conditions when selecting inputs for
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// usage when funding a channel.
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LockOutpoint(o wire.OutPoint)
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// UnlockOutpoint unlocks an previously locked output, marking it
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// eligible for coin seleciton.
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UnlockOutpoint(o wire.OutPoint)
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// ImportScript imports the serialize public key script, or redeem
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// script into the wallet's database. Scripts to be imported include
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// the 2-of-2 script for funding transactions, commitment scripts,
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// HTLCs scripts, and so on.
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ImportScript(b []byte) error
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// PublishTransaction performs cursory validation (dust checks, etc),
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// then finally broadcasts the passed transaction to the Bitcoin network.
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PublishTransaction(tx *wire.MsgTx) error
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// Start initializes the wallet, making any neccessary connections,
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// starting up required goroutines etc.
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@ -101,11 +122,147 @@ type WalletController interface {
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// Stop signals the wallet for shutdown. Shutdown may entail closing
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// any active sockets, database handles, stopping goroutines, etc.
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Stop() error
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// WaitForShutdown blocks until the wallet finishes the shutdown
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// procedure triggered by a prior call to Stop().
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WaitForShutdown() error
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// TODO(roasbeef): ImportPriv?
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// * segwitty flag?
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}
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// BlockChainIO is a dedicated source which will be used to obtain queries
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// related to the current state of the blockchain. The data returned by each of
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// the defined methods within this interface should always return the most up
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// to date data possible.
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//
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// TODO(roasbeef): move to diff package perhaps?
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type BlockChainIO interface {
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// GetCurrentHeight returns the current height of the valid most-work
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// chain the implementation is aware of.
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GetCurrentHeight() (int32, error)
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// GetTxOut returns the original output referenced by the passed
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// outpoint.
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GetUtxo(txid *wire.ShaHash, index uint32) (*wire.TxOut, error)
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// GetTransaction returns the full transaction identified by the passed
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// transaction ID.
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GetTransaction(txid *wire.ShaHash) (*wire.MsgTx, error)
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}
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// SignDescriptor houses the necessary information required to succesfully sign
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// a given output. This struct is used by the Signer interface in order to gain
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// access to critial data needed to generate a valid signature.
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type SignDescriptor struct {
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// Pubkey is the public key to which the signature should be generated
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// over. The Signer should then generate a signature with the private
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// key corresponding to this public key.
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PubKey *btcec.PublicKey
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// RedeemScript is the full script required to properly redeem the
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// output. This field will only be populated if a p2wsh or a p2sh
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// output is being signed.
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RedeemScript []byte
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// Output is the target output which should be signed. The PkScript and
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// Value fields within the output should be properly populated,
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// otherwise an invalid signature may be generated.
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Output *wire.TxOut
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// HashType is the target sighash type that should be used when
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// generating the final sighash, and signature.
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HashType txscript.SigHashType
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// SigHashes is the pre-computed sighash midstate to be used when
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// generating the final sighash for signing.
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SigHashes *txscript.TxSigHashes
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// InputIndex is the target input within the transaction that should be
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// signed.
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InputIndex int
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}
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// Signer represents an abstract object capable of generating raw signatures as
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// well as full complete input scripts given a valid SignDescriptor and
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// transaction. This interface fully abstracts away signing paving the way for
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// Signer implementations such as hardware wallets, hardware tokens, HSM's, or
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// simply a regular wallet.
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type Signer interface {
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// SignOutputRaw generates a signature for the passed transaction
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// according to the data within the passed SignDescriptor.
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//
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// NOTE: The resulting signature should be void of a sighash byte.
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SignOutputRaw(tx *wire.MsgTx, signDesc *SignDescriptor) ([]byte, error)
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// ComputeInputScript generates a complete InputIndex for the passed
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// transaction with the signature as defined within the passed
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// SignDescriptor. This method should be capable of generating the
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// proper input script for both regular p2wkh output and p2wkh outputs
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// nested within a regualr p2sh output.
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ComputeInputScript(tx *wire.MsgTx, signDesc *SignDescriptor) (*InputScript, error)
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}
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// WalletDriver represents a "driver" for a particular concrete
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// WalletController implementation. A driver is indentified by a globally
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// unique string identifier along with a 'New()' method which is responsible
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// for initializing a particular WalletController concrete implementation.
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type WalletDriver struct {
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// WalletType is a string which uniquely identifes the WalletController
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// that this driver, drives.
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WalletType string
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// New creates a new instance of a concrete WalletController
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// implementation given a variadic set up arguments. The function takes
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// a varidaic number of interface paramters in order to provide
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// initialization flexibility, thereby accomodating several potential
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// WalletController implementations.
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New func(args ...interface{}) (WalletController, error)
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}
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var (
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wallets = make(map[string]*WalletDriver)
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registerMtx sync.Mutex
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)
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// RegisteredWallets returns a slice of all currently registered notifiers.
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//
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// NOTE: This function is safe for concurrent access.
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func RegisteredWallets() []*WalletDriver {
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registerMtx.Lock()
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defer registerMtx.Unlock()
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registeredWallets := make([]*WalletDriver, 0, len(wallets))
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for _, wallet := range wallets {
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registeredWallets = append(registeredWallets, wallet)
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}
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return registeredWallets
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}
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// RegisterWallet registers a WalletDriver which is capable of driving a
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// concrete WalletController interface. In the case that this driver has
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// already been registered, an error is returned.
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//
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// NOTE: This function is safe for concurrent access.
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func RegisterWallet(driver *WalletDriver) error {
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registerMtx.Lock()
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defer registerMtx.Unlock()
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if _, ok := wallets[driver.WalletType]; ok {
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return fmt.Errorf("wallet already registered")
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}
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wallets[driver.WalletType] = driver
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return nil
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}
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// SupportedWallets returns a slice of strings that represents the walelt
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// drivers that have been registered and are therefore supported.
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//
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// NOTE: This function is safe for concurrent access.
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func SupportedWallets() []string {
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registerMtx.Lock()
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defer registerMtx.Unlock()
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supportedWallets := make([]string, 0, len(wallets))
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for walletName := range wallets {
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supportedWallets = append(supportedWallets, walletName)
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}
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return supportedWallets
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}
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