lnd.xprv/lnrpc/walletrpc/walletkit_server.go

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// +build walletrpc
package walletrpc
import (
"bytes"
"fmt"
"io/ioutil"
"os"
"path/filepath"
"github.com/btcsuite/btcd/wire"
"github.com/lightningnetwork/lnd/keychain"
"github.com/lightningnetwork/lnd/lnrpc"
"github.com/lightningnetwork/lnd/lnrpc/signrpc"
"github.com/lightningnetwork/lnd/lnwallet"
"golang.org/x/net/context"
"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",
}},
}
// 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, lnwallet.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
}