loop/lndclient/walletkit_client.go

package lndclient

import (
	"context"

	"github.com/btcsuite/btcd/btcec"
	"github.com/btcsuite/btcd/wire"
	"github.com/btcsuite/btcutil"
	"github.com/lightninglabs/loop/utils"
	"github.com/lightningnetwork/lnd/keychain"
	"github.com/lightningnetwork/lnd/lnrpc/signrpc"
	"github.com/lightningnetwork/lnd/lnrpc/walletrpc"
	"github.com/lightningnetwork/lnd/lnwallet"
	"google.golang.org/grpc"
)

// WalletKitClient exposes wallet functionality.
type WalletKitClient interface {
	DeriveNextKey(ctx context.Context, family int32) (
		*keychain.KeyDescriptor, error)

	DeriveKey(ctx context.Context, locator *keychain.KeyLocator) (
		*keychain.KeyDescriptor, error)

	NextAddr(ctx context.Context) (btcutil.Address, error)

	PublishTransaction(ctx context.Context, tx *wire.MsgTx) error

	SendOutputs(ctx context.Context, outputs []*wire.TxOut,
		feeRate lnwallet.SatPerKWeight) (*wire.MsgTx, error)

	EstimateFee(ctx context.Context, confTarget int32) (lnwallet.SatPerKWeight,
		error)
}

type walletKitClient struct {
	client walletrpc.WalletKitClient
}

func newWalletKitClient(conn *grpc.ClientConn) *walletKitClient {
	return &walletKitClient{
		client: walletrpc.NewWalletKitClient(conn),
	}
}

func (m *walletKitClient) DeriveNextKey(ctx context.Context, family int32) (
	*keychain.KeyDescriptor, error) {

	rpcCtx, cancel := context.WithTimeout(ctx, rpcTimeout)
	defer cancel()

	resp, err := m.client.DeriveNextKey(rpcCtx, &walletrpc.KeyReq{
		KeyFamily: family,
	})
	if err != nil {
		return nil, err
	}

	key, err := btcec.ParsePubKey(resp.RawKeyBytes, btcec.S256())
	if err != nil {
		return nil, err
	}

	return &keychain.KeyDescriptor{
		KeyLocator: keychain.KeyLocator{
			Family: keychain.KeyFamily(resp.KeyLoc.KeyFamily),
			Index:  uint32(resp.KeyLoc.KeyIndex),
		},
		PubKey: key,
	}, nil
}

func (m *walletKitClient) DeriveKey(ctx context.Context, in *keychain.KeyLocator) (
	*keychain.KeyDescriptor, error) {

	rpcCtx, cancel := context.WithTimeout(ctx, rpcTimeout)
	defer cancel()

	resp, err := m.client.DeriveKey(rpcCtx, &signrpc.KeyLocator{
		KeyFamily: int32(in.Family),
		KeyIndex:  int32(in.Index),
	})
	if err != nil {
		return nil, err
	}

	key, err := btcec.ParsePubKey(resp.RawKeyBytes, btcec.S256())
	if err != nil {
		return nil, err
	}

	return &keychain.KeyDescriptor{
		KeyLocator: *in,
		PubKey:     key,
	}, nil
}

func (m *walletKitClient) NextAddr(ctx context.Context) (
	btcutil.Address, error) {

	rpcCtx, cancel := context.WithTimeout(ctx, rpcTimeout)
	defer cancel()

	resp, err := m.client.NextAddr(rpcCtx, &walletrpc.AddrRequest{})
	if err != nil {
		return nil, err
	}

	addr, err := btcutil.DecodeAddress(resp.Addr, nil)
	if err != nil {
		return nil, err
	}

	return addr, nil
}

func (m *walletKitClient) PublishTransaction(ctx context.Context,
	tx *wire.MsgTx) error {

	txHex, err := utils.EncodeTx(tx)
	if err != nil {
		return err
	}

	rpcCtx, cancel := context.WithTimeout(ctx, rpcTimeout)
	defer cancel()

	_, err = m.client.PublishTransaction(rpcCtx, &walletrpc.Transaction{
		TxHex: txHex,
	})

	return err
}

func (m *walletKitClient) SendOutputs(ctx context.Context,
	outputs []*wire.TxOut, feeRate lnwallet.SatPerKWeight) (
	*wire.MsgTx, error) {

	rpcOutputs := make([]*signrpc.TxOut, len(outputs))
	for i, output := range outputs {
		rpcOutputs[i] = &signrpc.TxOut{
			PkScript: output.PkScript,
			Value:    output.Value,
		}
	}

	rpcCtx, cancel := context.WithTimeout(ctx, rpcTimeout)
	defer cancel()

	resp, err := m.client.SendOutputs(rpcCtx, &walletrpc.SendOutputsRequest{
		Outputs:  rpcOutputs,
		SatPerKw: int64(feeRate),
	})
	if err != nil {
		return nil, err
	}

	tx, err := utils.DecodeTx(resp.RawTx)
	if err != nil {
		return nil, err
	}

	return tx, nil
}

func (m *walletKitClient) EstimateFee(ctx context.Context, confTarget int32) (
	lnwallet.SatPerKWeight, error) {

	rpcCtx, cancel := context.WithTimeout(ctx, rpcTimeout)
	defer cancel()

	resp, err := m.client.EstimateFee(rpcCtx, &walletrpc.EstimateFeeRequest{
		ConfTarget: int32(confTarget),
	})
	if err != nil {
		return 0, err
	}

	return lnwallet.SatPerKWeight(resp.SatPerKw), nil
}