multi: forward SendCoins call over RPC

go.mod

@@ -9,10 +9,9 @@ require (
 	github.com/btcsuite/btclog v0.0.0-20170628155309-84c8d2346e9f
 	github.com/btcsuite/btcutil v1.0.3-0.20210527170813-e2ba6805a890
 	github.com/btcsuite/btcutil/psbt v1.0.3-0.20210527170813-e2ba6805a890
-	github.com/btcsuite/btcwallet v0.12.1-0.20210916213031-d0868cb9dd94
+	github.com/btcsuite/btcwallet v0.12.1-0.20211008000044-541a8512ccfe
 	github.com/btcsuite/btcwallet/wallet/txauthor v1.1.0
 	github.com/btcsuite/btcwallet/wallet/txrules v1.1.0
-	github.com/btcsuite/btcwallet/wallet/txsizes v1.1.0 // indirect
 	github.com/btcsuite/btcwallet/walletdb v1.3.6-0.20210803004036-eebed51155ec
 	github.com/btcsuite/btcwallet/wtxmgr v1.3.1-0.20210822222949-9b5a201c344c
 	github.com/coreos/go-systemd v0.0.0-20190719114852-fd7a80b32e1f

go.sum

@@ -91,17 +91,15 @@ github.com/btcsuite/btcutil v1.0.3-0.20210527170813-e2ba6805a890/go.mod h1:0DVlH
 github.com/btcsuite/btcutil/psbt v1.0.3-0.20201208143702-a53e38424cce/go.mod h1:LVveMu4VaNSkIRTZu2+ut0HDBRuYjqGocxDMNS1KuGQ=
 github.com/btcsuite/btcutil/psbt v1.0.3-0.20210527170813-e2ba6805a890 h1:0xUNvvwJ7RjzBs4nCF+YrK28S5P/b4uHkpPxY1ovGY4=
 github.com/btcsuite/btcutil/psbt v1.0.3-0.20210527170813-e2ba6805a890/go.mod h1:LVveMu4VaNSkIRTZu2+ut0HDBRuYjqGocxDMNS1KuGQ=
-github.com/btcsuite/btcwallet v0.12.1-0.20210916213031-d0868cb9dd94 h1:Bx+xu606h2sZNn5VaZMWvI0GtlGE+y+dHI4hbL5Ld6k=
-github.com/btcsuite/btcwallet v0.12.1-0.20210916213031-d0868cb9dd94/go.mod h1:gHFk6GQ4IP/a8z6mfwK85GagUPxvAxCmgFy/whrBXhI=
+github.com/btcsuite/btcwallet v0.12.1-0.20211008000044-541a8512ccfe h1:G7l/t3Y+B7jhRzcKs9z00KdocqdEqaXstwa0KSxH1bQ=
+github.com/btcsuite/btcwallet v0.12.1-0.20211008000044-541a8512ccfe/go.mod h1:iLN1lG1MW0eREm+SikmPO8AZPz5NglBTEK/ErqkjGpo=
 github.com/btcsuite/btcwallet/wallet/txauthor v1.0.0/go.mod h1:VufDts7bd/zs3GV13f/lXc/0lXrPnvxD/NvmpG/FEKU=
-github.com/btcsuite/btcwallet/wallet/txauthor v1.0.1-0.20210329233242-e0607006dce6/go.mod h1:VufDts7bd/zs3GV13f/lXc/0lXrPnvxD/NvmpG/FEKU=
 github.com/btcsuite/btcwallet/wallet/txauthor v1.1.0 h1:8pO0pvPX1rFRfRiol4oV6kX7dY5y4chPwhfVwUfvwtk=
 github.com/btcsuite/btcwallet/wallet/txauthor v1.1.0/go.mod h1:ktYuJyumYtwG+QQ832Q+kqvxWJRAei3Nqs5qhSn4nww=
 github.com/btcsuite/btcwallet/wallet/txrules v1.0.0/go.mod h1:UwQE78yCerZ313EXZwEiu3jNAtfXj2n2+c8RWiE/WNA=
 github.com/btcsuite/btcwallet/wallet/txrules v1.1.0 h1:Vg8G8zhNVjaCdwJg2QOmLoWn4RTP7K0J9xlwY8CJnLY=
 github.com/btcsuite/btcwallet/wallet/txrules v1.1.0/go.mod h1:Zn9UTqpiTH+HOd5BLzSBzULzlOPmcoeyQIA0cp0WbQQ=
 github.com/btcsuite/btcwallet/wallet/txsizes v1.0.0/go.mod h1:pauEU8UuMFiThe5PB3EO+gO5kx87Me5NvdQDsTuq6cs=
-github.com/btcsuite/btcwallet/wallet/txsizes v1.0.1-0.20210519225359-6ab9b615576f/go.mod h1:pauEU8UuMFiThe5PB3EO+gO5kx87Me5NvdQDsTuq6cs=
 github.com/btcsuite/btcwallet/wallet/txsizes v1.1.0 h1:wZnOolEAeNOHzHTnznw/wQv+j35ftCIokNrnOTOU5o8=
 github.com/btcsuite/btcwallet/wallet/txsizes v1.1.0/go.mod h1:pauEU8UuMFiThe5PB3EO+gO5kx87Me5NvdQDsTuq6cs=
 github.com/btcsuite/btcwallet/walletdb v1.3.4/go.mod h1:oJDxAEUHVtnmIIBaa22wSBPTVcs6hUp5NKWmI8xDwwU=

lnrpc/walletrpc/walletkit_server.go

@@ -1118,7 +1118,7 @@ func (w *WalletKit) FundPsbt(_ context.Context,
 		// lock any coins but might still change the wallet DB by
 		// generating a new change address.
 		changeIndex, err = w.cfg.Wallet.FundPsbt(
-			packet, feeSatPerKW, account,
+			packet, minConfs, feeSatPerKW, account,
 		)
 		if err != nil {
 			return fmt.Errorf("wallet couldn't fund PSBT: %v", err)

lntest/mock/walletcontroller.go

@@ -169,7 +169,7 @@ func (w *WalletController) ListLeasedOutputs() ([]*wtxmgr.LockedOutput, error) {
 }
 
 // FundPsbt currently does nothing.
-func (w *WalletController) FundPsbt(_ *psbt.Packet,
+func (w *WalletController) FundPsbt(_ *psbt.Packet, _ int32,
 	_ chainfee.SatPerKWeight, _ string) (int32, error) {
 
 	return 0, nil

lnwallet/btcwallet/btcwallet.go

@@ -642,7 +642,8 @@ func (b *BtcWallet) ImportPublicKey(pubKey *btcec.PublicKey,
 //
 // This is a part of the WalletController interface.
 func (b *BtcWallet) SendOutputs(outputs []*wire.TxOut,
-	feeRate chainfee.SatPerKWeight, minConfs int32, label string) (*wire.MsgTx, error) {
+	feeRate chainfee.SatPerKWeight, minConfs int32,
+	label string) (*wire.MsgTx, error) {
 
 	// Convert our fee rate from sat/kw to sat/kb since it's required by
 	// SendOutputs.
@@ -1080,7 +1081,7 @@ func (b *BtcWallet) ListTransactionDetails(startHeight, endHeight int32,
 // responsibility to lock the inputs before handing them out.
 //
 // This is a part of the WalletController interface.
-func (b *BtcWallet) FundPsbt(packet *psbt.Packet,
+func (b *BtcWallet) FundPsbt(packet *psbt.Packet, minConfs int32,
 	feeRate chainfee.SatPerKWeight, accountName string) (int32, error) {
 
 	// The fee rate is passed in using units of sat/kw, so we'll convert
@@ -1115,7 +1116,7 @@ func (b *BtcWallet) FundPsbt(packet *psbt.Packet,
 	// Let the wallet handle coin selection and/or fee estimation based on
 	// the partial TX information in the packet.
 	return b.wallet.FundPsbt(
-		packet, keyScope, accountNum, feeSatPerKB,
+		packet, keyScope, minConfs, accountNum, feeSatPerKB,
 		b.cfg.CoinSelectionStrategy,
 	)
 }

lnwallet/interface.go

@@ -350,8 +350,8 @@ type WalletController interface {
 	// fee rate, an error is returned. No lock lease is acquired for any of
 	// the selected/validated inputs. It is in the caller's responsibility
 	// to lock the inputs before handing them out.
-	FundPsbt(packet *psbt.Packet, feeRate chainfee.SatPerKWeight,
-		account string) (int32, error)
+	FundPsbt(packet *psbt.Packet, minConfs int32,
+		feeRate chainfee.SatPerKWeight, account string) (int32, error)
 
 	// FinalizePsbt expects a partial transaction with all inputs and
 	// outputs fully declared and tries to sign all inputs that belong to

lnwallet/rpcwallet/rpcwallet.go

@@ -11,16 +11,20 @@ import (
 	"time"
 
 	"github.com/btcsuite/btcd/btcec"
+	"github.com/btcsuite/btcd/txscript"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/btcsuite/btcutil"
 	"github.com/btcsuite/btcutil/hdkeychain"
 	"github.com/btcsuite/btcwallet/waddrmgr"
+	btcwallet "github.com/btcsuite/btcwallet/wallet"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/keychain"
 	"github.com/lightningnetwork/lnd/lncfg"
 	"github.com/lightningnetwork/lnd/lnrpc/signrpc"
 	"github.com/lightningnetwork/lnd/lnrpc/walletrpc"
 	"github.com/lightningnetwork/lnd/lnwallet"
+	"github.com/lightningnetwork/lnd/lnwallet/chainfee"
+	"github.com/lightningnetwork/lnd/lnwallet/chanfunding"
 	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/macaroons"
 	"google.golang.org/grpc"
@@ -139,6 +143,26 @@ func (r *RPCKeyRing) NewAddress(addrType lnwallet.AddressType, change bool,
 	return localAddr, nil
 }
 
+// LastUnusedAddress returns the last *unused* address known by the wallet. An
+// address is unused if it hasn't received any payments. This can be useful in
+// UIs in order to continually show the "freshest" address without having to
+// worry about "address inflation" caused by continual refreshing. Similar to
+// NewAddress it can derive a specified address type, and also optionally a
+// change address. The account parameter must be non-empty as it determines
+// which account the address should be generated from.
+func (r *RPCKeyRing) LastUnusedAddress(lnwallet.AddressType,
+	string) (btcutil.Address, error) {
+
+	// Because the underlying wallet will create a new address if the last
+	// derived address has been used in the meantime, we would need to proxy
+	// that call as well. But since that's deep within the btcwallet code,
+	// we cannot easily proxy it without more refactoring. Since this is an
+	// address type that is probably not widely used we can probably get
+	// away with not supporting it.
+	return nil, fmt.Errorf("unused address types are not supported when " +
+		"remote signing is enabled")
+}
+
 // ImportAccount imports an account backed by an account extended public key.
 // The master key fingerprint denotes the fingerprint of the root key
 // corresponding to the account public key (also known as the key with
@@ -265,6 +289,67 @@ func (r *RPCKeyRing) ImportPublicKey(pubKey *btcec.PublicKey,
 	return nil
 }
 
+// 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, a non-nil error will be returned.
+//
+// NOTE: This method requires the global coin selection lock to be held.
+//
+// This is a part of the WalletController interface.
+func (r *RPCKeyRing) SendOutputs(outputs []*wire.TxOut,
+	feeRate chainfee.SatPerKWeight, minConfs int32,
+	label string) (*wire.MsgTx, error) {
+
+	tx, err := r.WalletController.SendOutputs(
+		outputs, feeRate, minConfs, label,
+	)
+	if err != nil && err != btcwallet.ErrTxUnsigned {
+		return nil, err
+	}
+	if err == nil {
+		// This shouldn't happen since our wallet controller is watch-
+		// only and can't sign the TX.
+		return tx, nil
+	}
+
+	// We know at this point that we only have inputs from our own wallet.
+	// So we can just compute the input script using the remote signer.
+	signDesc := input.SignDescriptor{
+		HashType:  txscript.SigHashAll,
+		SigHashes: txscript.NewTxSigHashes(tx),
+	}
+	for i, txIn := range tx.TxIn {
+		// We can only sign this input if it's ours, so we'll ask the
+		// watch-only wallet if it can map this outpoint into a coin we
+		// own. If not, then we can't continue because our wallet state
+		// is out of sync.
+		info, err := r.coinFromOutPoint(txIn.PreviousOutPoint)
+		if err != nil {
+			return nil, fmt.Errorf("error looking up utxo: %v", err)
+		}
+
+		// Now that we know the input is ours, we'll populate the
+		// signDesc with the per input unique information.
+		signDesc.Output = &wire.TxOut{
+			Value:    info.Value,
+			PkScript: info.PkScript,
+		}
+		signDesc.InputIndex = i
+
+		// Finally, we'll sign the input as is, and populate the input
+		// with the witness and sigScript (if needed).
+		inputScript, err := r.ComputeInputScript(tx, &signDesc)
+		if err != nil {
+			return nil, err
+		}
+
+		txIn.SignatureScript = inputScript.SigScript
+		txIn.Witness = inputScript.Witness
+	}
+
+	return tx, r.WalletController.PublishTransaction(tx, label)
+}
+
 // 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.
@@ -534,6 +619,26 @@ func (r *RPCKeyRing) ComputeInputScript(tx *wire.MsgTx,
 	}, nil
 }
 
+// coinFromOutPoint attempts to locate details pertaining to a coin based on
+// its outpoint. If the coin isn't under the control of the backing watch-only
+// wallet, then an error is returned.
+func (r *RPCKeyRing) coinFromOutPoint(op wire.OutPoint) (*chanfunding.Coin,
+	error) {
+
+	inputInfo, err := r.WalletController.FetchInputInfo(&op)
+	if err != nil {
+		return nil, err
+	}
+
+	return &chanfunding.Coin{
+		TxOut: wire.TxOut{
+			Value:    int64(inputInfo.Value),
+			PkScript: inputInfo.PkScript,
+		},
+		OutPoint: inputInfo.OutPoint,
+	}, nil
+}
+
 // toRPCSignReq converts the given raw transaction and sign descriptors into
 // their corresponding RPC counterparts.
 func toRPCSignReq(tx *wire.MsgTx,

rpcserver.go

@@ -1037,7 +1037,7 @@ func (r *rpcServer) sendCoinsOnChain(paymentMap map[string]int64,
 		return nil, err
 	}
 
-	// If that checks out, we're failry confident that creating sending to
+	// If that checks out, we're fairly confident that creating sending to
 	// these outputs will keep the wallet balance above the reserve.
 	tx, err := r.server.cc.Wallet.SendOutputs(
 		outputs, feeRate, minConfs, label,