lnd.xprv/lnrpc/walletrpc/walletkit_server.go

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// +build walletrpc
package walletrpc
import (
"bytes"
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"context"
"errors"
"fmt"
"io/ioutil"
"os"
"path/filepath"
"github.com/btcsuite/btcd/chaincfg/chainhash"
"github.com/btcsuite/btcd/txscript"
"github.com/btcsuite/btcd/wire"
"github.com/lightningnetwork/lnd/input"
"github.com/lightningnetwork/lnd/keychain"
"github.com/lightningnetwork/lnd/lnrpc"
"github.com/lightningnetwork/lnd/lnrpc/signrpc"
"github.com/lightningnetwork/lnd/lnwallet"
"github.com/lightningnetwork/lnd/lnwallet/chainfee"
"github.com/lightningnetwork/lnd/sweep"
"google.golang.org/grpc"
"gopkg.in/macaroon-bakery.v2/bakery"
)
const (
// subServerName is the name of the sub rpc server. We'll use this name
// to register ourselves, and we also require that the main
// SubServerConfigDispatcher instance recognize as the name of our
subServerName = "WalletKitRPC"
)
var (
// macaroonOps are the set of capabilities that our minted macaroon (if
// it doesn't already exist) will have.
macaroonOps = []bakery.Op{
{
Entity: "address",
Action: "write",
},
{
Entity: "address",
Action: "read",
},
{
Entity: "onchain",
Action: "write",
},
{
Entity: "onchain",
Action: "read",
},
}
// macPermissions maps RPC calls to the permissions they require.
macPermissions = map[string][]bakery.Op{
"/walletrpc.WalletKit/DeriveNextKey": {{
Entity: "address",
Action: "read",
}},
"/walletrpc.WalletKit/DeriveKey": {{
Entity: "address",
Action: "read",
}},
"/walletrpc.WalletKit/NextAddr": {{
Entity: "address",
Action: "read",
}},
"/walletrpc.WalletKit/PublishTransaction": {{
Entity: "onchain",
Action: "write",
}},
"/walletrpc.WalletKit/SendOutputs": {{
Entity: "onchain",
Action: "write",
}},
"/walletrpc.WalletKit/EstimateFee": {{
Entity: "onchain",
Action: "read",
}},
"/walletrpc.WalletKit/PendingSweeps": {{
Entity: "onchain",
Action: "read",
}},
"/walletrpc.WalletKit/BumpFee": {{
Entity: "onchain",
Action: "write",
}},
}
// DefaultWalletKitMacFilename is the default name of the wallet kit
// macaroon that we expect to find via a file handle within the main
// configuration file in this package.
DefaultWalletKitMacFilename = "walletkit.macaroon"
)
// WalletKit is a sub-RPC server that exposes a tool kit which allows clients
// to execute common wallet operations. This includes requesting new addresses,
// keys (for contracts!), and publishing transactions.
type WalletKit struct {
cfg *Config
}
// A compile time check to ensure that WalletKit fully implements the
// WalletKitServer gRPC service.
var _ WalletKitServer = (*WalletKit)(nil)
// New creates a new instance of the WalletKit sub-RPC server.
func New(cfg *Config) (*WalletKit, lnrpc.MacaroonPerms, error) {
// If the path of the wallet kit macaroon wasn't specified, then we'll
// assume that it's found at the default network directory.
if cfg.WalletKitMacPath == "" {
cfg.WalletKitMacPath = filepath.Join(
cfg.NetworkDir, DefaultWalletKitMacFilename,
)
}
// Now that we know the full path of the wallet kit macaroon, we can
// check to see if we need to create it or not.
macFilePath := cfg.WalletKitMacPath
if !lnrpc.FileExists(macFilePath) && cfg.MacService != nil {
log.Infof("Baking macaroons for WalletKit RPC Server at: %v",
macFilePath)
// At this point, we know that the wallet kit macaroon doesn't
// yet, exist, so we need to create it with the help of the
// main macaroon service.
walletKitMac, err := cfg.MacService.Oven.NewMacaroon(
context.Background(), bakery.LatestVersion, nil,
macaroonOps...,
)
if err != nil {
return nil, nil, err
}
walletKitMacBytes, err := walletKitMac.M().MarshalBinary()
if err != nil {
return nil, nil, err
}
err = ioutil.WriteFile(macFilePath, walletKitMacBytes, 0644)
if err != nil {
os.Remove(macFilePath)
return nil, nil, err
}
}
walletKit := &WalletKit{
cfg: cfg,
}
return walletKit, macPermissions, nil
}
// Start launches any helper goroutines required for the sub-server to function.
//
// NOTE: This is part of the lnrpc.SubServer interface.
func (w *WalletKit) Start() error {
return nil
}
// Stop signals any active goroutines for a graceful closure.
//
// NOTE: This is part of the lnrpc.SubServer interface.
func (w *WalletKit) Stop() error {
return nil
}
// Name returns a unique string representation of the sub-server. This can be
// used to identify the sub-server and also de-duplicate them.
//
// NOTE: This is part of the lnrpc.SubServer interface.
func (w *WalletKit) Name() string {
return subServerName
}
// RegisterWithRootServer will be called by the root gRPC server to direct a
// sub RPC server to register itself with the main gRPC root server. Until this
// is called, each sub-server won't be able to have requests routed towards it.
//
// NOTE: This is part of the lnrpc.SubServer interface.
func (w *WalletKit) RegisterWithRootServer(grpcServer *grpc.Server) error {
// We make sure that we register it with the main gRPC server to ensure
// all our methods are routed properly.
RegisterWalletKitServer(grpcServer, w)
log.Debugf("WalletKit RPC server successfully registered with " +
"root gRPC server")
return nil
}
// DeriveNextKey attempts to derive the *next* key within the key family
// (account in BIP43) specified. This method should return the next external
// child within this branch.
func (w *WalletKit) DeriveNextKey(ctx context.Context,
req *KeyReq) (*signrpc.KeyDescriptor, error) {
nextKeyDesc, err := w.cfg.KeyRing.DeriveNextKey(
keychain.KeyFamily(req.KeyFamily),
)
if err != nil {
return nil, err
}
return &signrpc.KeyDescriptor{
KeyLoc: &signrpc.KeyLocator{
KeyFamily: int32(nextKeyDesc.Family),
KeyIndex: int32(nextKeyDesc.Index),
},
RawKeyBytes: nextKeyDesc.PubKey.SerializeCompressed(),
}, nil
}
// DeriveKey attempts to derive an arbitrary key specified by the passed
// KeyLocator.
func (w *WalletKit) DeriveKey(ctx context.Context,
req *signrpc.KeyLocator) (*signrpc.KeyDescriptor, error) {
keyDesc, err := w.cfg.KeyRing.DeriveKey(keychain.KeyLocator{
Family: keychain.KeyFamily(req.KeyFamily),
Index: uint32(req.KeyIndex),
})
if err != nil {
return nil, err
}
return &signrpc.KeyDescriptor{
KeyLoc: &signrpc.KeyLocator{
KeyFamily: int32(keyDesc.Family),
KeyIndex: int32(keyDesc.Index),
},
RawKeyBytes: keyDesc.PubKey.SerializeCompressed(),
}, nil
}
// NextAddr returns the next unused address within the wallet.
func (w *WalletKit) NextAddr(ctx context.Context,
req *AddrRequest) (*AddrResponse, error) {
addr, err := w.cfg.Wallet.NewAddress(lnwallet.WitnessPubKey, false)
if err != nil {
return nil, err
}
return &AddrResponse{
Addr: addr.String(),
}, nil
}
// Attempts to publish the passed transaction to the network. Once this returns
// without an error, the wallet will continually attempt to re-broadcast the
// transaction on start up, until it enters the chain.
func (w *WalletKit) PublishTransaction(ctx context.Context,
req *Transaction) (*PublishResponse, error) {
switch {
// If the client doesn't specify a transaction, then there's nothing to
// publish.
case len(req.TxHex) == 0:
return nil, fmt.Errorf("must provide a transaction to " +
"publish")
}
tx := &wire.MsgTx{}
txReader := bytes.NewReader(req.TxHex)
if err := tx.Deserialize(txReader); err != nil {
return nil, err
}
err := w.cfg.Wallet.PublishTransaction(tx)
if err != nil {
return nil, err
}
return &PublishResponse{}, nil
}
// SendOutputs is similar to the existing sendmany call in Bitcoind, and allows
// the caller to create a transaction that sends to several outputs at once.
// This is ideal when wanting to batch create a set of transactions.
func (w *WalletKit) SendOutputs(ctx context.Context,
req *SendOutputsRequest) (*SendOutputsResponse, error) {
switch {
// If the client didn't specify any outputs to create, then we can't
// proceed .
case len(req.Outputs) == 0:
return nil, fmt.Errorf("must specify at least one output " +
"to create")
}
// Before we can request this transaction to be created, we'll need to
// amp the protos back into the format that the internal wallet will
// recognize.
outputsToCreate := make([]*wire.TxOut, 0, len(req.Outputs))
for _, output := range req.Outputs {
outputsToCreate = append(outputsToCreate, &wire.TxOut{
Value: output.Value,
PkScript: output.PkScript,
})
}
// Now that we have the outputs mapped, we can request that the wallet
// attempt to create this transaction.
tx, err := w.cfg.Wallet.SendOutputs(
outputsToCreate, chainfee.SatPerKWeight(req.SatPerKw),
)
if err != nil {
return nil, err
}
var b bytes.Buffer
if err := tx.Serialize(&b); err != nil {
return nil, err
}
return &SendOutputsResponse{
RawTx: b.Bytes(),
}, nil
}
// EstimateFee attempts to query the internal fee estimator of the wallet to
// determine the fee (in sat/kw) to attach to a transaction in order to achieve
// the confirmation target.
func (w *WalletKit) EstimateFee(ctx context.Context,
req *EstimateFeeRequest) (*EstimateFeeResponse, error) {
switch {
// A confirmation target of zero doesn't make any sense. Similarly, we
// reject confirmation targets of 1 as they're unreasonable.
case req.ConfTarget == 0 || req.ConfTarget == 1:
return nil, fmt.Errorf("confirmation target must be greater " +
"than 1")
}
satPerKw, err := w.cfg.FeeEstimator.EstimateFeePerKW(
uint32(req.ConfTarget),
)
if err != nil {
return nil, err
}
return &EstimateFeeResponse{
SatPerKw: int64(satPerKw),
}, nil
}
// PendingSweeps returns lists of on-chain outputs that lnd is currently
// attempting to sweep within its central batching engine. Outputs with similar
// fee rates are batched together in order to sweep them within a single
// transaction. The fee rate of each sweeping transaction is determined by
// taking the average fee rate of all the outputs it's trying to sweep.
func (w *WalletKit) PendingSweeps(ctx context.Context,
in *PendingSweepsRequest) (*PendingSweepsResponse, error) {
// Retrieve all of the outputs the UtxoSweeper is currently trying to
// sweep.
pendingInputs, err := w.cfg.Sweeper.PendingInputs()
if err != nil {
return nil, err
}
// Convert them into their respective RPC format.
rpcPendingSweeps := make([]*PendingSweep, 0, len(pendingInputs))
for _, pendingInput := range pendingInputs {
var witnessType WitnessType
switch pendingInput.WitnessType {
case input.CommitmentTimeLock:
witnessType = WitnessType_COMMITMENT_TIME_LOCK
case input.CommitmentNoDelay:
witnessType = WitnessType_COMMITMENT_NO_DELAY
case input.CommitmentRevoke:
witnessType = WitnessType_COMMITMENT_REVOKE
case input.HtlcOfferedRevoke:
witnessType = WitnessType_HTLC_OFFERED_REVOKE
case input.HtlcAcceptedRevoke:
witnessType = WitnessType_HTLC_ACCEPTED_REVOKE
case input.HtlcOfferedTimeoutSecondLevel:
witnessType = WitnessType_HTLC_OFFERED_TIMEOUT_SECOND_LEVEL
case input.HtlcAcceptedSuccessSecondLevel:
witnessType = WitnessType_HTLC_ACCEPTED_SUCCESS_SECOND_LEVEL
case input.HtlcOfferedRemoteTimeout:
witnessType = WitnessType_HTLC_OFFERED_REMOTE_TIMEOUT
case input.HtlcAcceptedRemoteSuccess:
witnessType = WitnessType_HTLC_ACCEPTED_REMOTE_SUCCESS
case input.HtlcSecondLevelRevoke:
witnessType = WitnessType_HTLC_SECOND_LEVEL_REVOKE
case input.WitnessKeyHash:
witnessType = WitnessType_WITNESS_KEY_HASH
case input.NestedWitnessKeyHash:
witnessType = WitnessType_NESTED_WITNESS_KEY_HASH
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case input.CommitmentAnchor:
witnessType = WitnessType_COMMITMENT_ANCHOR
default:
log.Warnf("Unhandled witness type %v for input %v",
pendingInput.WitnessType, pendingInput.OutPoint)
}
op := &lnrpc.OutPoint{
TxidBytes: pendingInput.OutPoint.Hash[:],
OutputIndex: pendingInput.OutPoint.Index,
}
amountSat := uint32(pendingInput.Amount)
satPerByte := uint32(pendingInput.LastFeeRate.FeePerKVByte() / 1000)
broadcastAttempts := uint32(pendingInput.BroadcastAttempts)
nextBroadcastHeight := uint32(pendingInput.NextBroadcastHeight)
requestedFee := pendingInput.Params.Fee
requestedFeeRate := uint32(requestedFee.FeeRate.FeePerKVByte() / 1000)
rpcPendingSweeps = append(rpcPendingSweeps, &PendingSweep{
Outpoint: op,
WitnessType: witnessType,
AmountSat: amountSat,
SatPerByte: satPerByte,
BroadcastAttempts: broadcastAttempts,
NextBroadcastHeight: nextBroadcastHeight,
RequestedSatPerByte: requestedFeeRate,
RequestedConfTarget: requestedFee.ConfTarget,
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Force: pendingInput.Params.Force,
})
}
return &PendingSweepsResponse{
PendingSweeps: rpcPendingSweeps,
}, nil
}
// unmarshallOutPoint converts an outpoint from its lnrpc type to its canonical
// type.
func unmarshallOutPoint(op *lnrpc.OutPoint) (*wire.OutPoint, error) {
if op == nil {
return nil, fmt.Errorf("empty outpoint provided")
}
var hash chainhash.Hash
switch {
case len(op.TxidBytes) == 0 && len(op.TxidStr) == 0:
fallthrough
case len(op.TxidBytes) != 0 && len(op.TxidStr) != 0:
return nil, fmt.Errorf("either TxidBytes or TxidStr must be " +
"specified, but not both")
// The hash was provided as raw bytes.
case len(op.TxidBytes) != 0:
copy(hash[:], op.TxidBytes)
// The hash was provided as a hex-encoded string.
case len(op.TxidStr) != 0:
h, err := chainhash.NewHashFromStr(op.TxidStr)
if err != nil {
return nil, err
}
hash = *h
}
return &wire.OutPoint{
Hash: hash,
Index: op.OutputIndex,
}, nil
}
// BumpFee allows bumping the fee rate of an arbitrary input. A fee preference
// can be expressed either as a specific fee rate or a delta of blocks in which
// the output should be swept on-chain within. If a fee preference is not
// explicitly specified, then an error is returned. The status of the input
// sweep can be checked through the PendingSweeps RPC.
func (w *WalletKit) BumpFee(ctx context.Context,
in *BumpFeeRequest) (*BumpFeeResponse, error) {
// Parse the outpoint from the request.
op, err := unmarshallOutPoint(in.Outpoint)
if err != nil {
return nil, err
}
// Construct the request's fee preference.
satPerKw := chainfee.SatPerKVByte(in.SatPerByte * 1000).FeePerKWeight()
feePreference := sweep.FeePreference{
ConfTarget: uint32(in.TargetConf),
FeeRate: satPerKw,
}
// We'll attempt to bump the fee of the input through the UtxoSweeper.
// If it is currently attempting to sweep the input, then it'll simply
// bump its fee, which will result in a replacement transaction (RBF)
// being broadcast. If it is not aware of the input however,
// lnwallet.ErrNotMine is returned.
params := sweep.ParamsUpdate{
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Fee: feePreference,
Force: in.Force,
}
_, err = w.cfg.Sweeper.UpdateParams(*op, params)
switch err {
case nil:
return &BumpFeeResponse{}, nil
case lnwallet.ErrNotMine:
break
default:
return nil, err
}
// Since we're unable to perform a bump through RBF, we'll assume the
// user is attempting to bump an unconfirmed transaction's fee rate by
// sweeping an output within it under control of the wallet with a
// higher fee rate, essentially performing a Child-Pays-For-Parent
// (CPFP).
//
// We'll gather all of the information required by the UtxoSweeper in
// order to sweep the output.
utxo, err := w.cfg.Wallet.FetchInputInfo(op)
if err != nil {
return nil, err
}
// We're only able to bump the fee of unconfirmed transactions.
if utxo.Confirmations > 0 {
return nil, errors.New("unable to bump fee of a confirmed " +
"transaction")
}
var witnessType input.WitnessType
switch utxo.AddressType {
case lnwallet.WitnessPubKey:
witnessType = input.WitnessKeyHash
case lnwallet.NestedWitnessPubKey:
witnessType = input.NestedWitnessKeyHash
default:
return nil, fmt.Errorf("unknown input witness %v", op)
}
signDesc := &input.SignDescriptor{
Output: &wire.TxOut{
PkScript: utxo.PkScript,
Value: int64(utxo.Value),
},
HashType: txscript.SigHashAll,
}
// We'll use the current height as the height hint since we're dealing
// with an unconfirmed transaction.
_, currentHeight, err := w.cfg.Chain.GetBestBlock()
if err != nil {
return nil, fmt.Errorf("unable to retrieve current height: %v",
err)
}
input := input.NewBaseInput(op, witnessType, signDesc, uint32(currentHeight))
if _, err = w.cfg.Sweeper.SweepInput(input, sweep.Params{Fee: feePreference}); err != nil {
return nil, err
}
return &BumpFeeResponse{}, nil
}