multi: add label to WalletController SendOutputs and dependent rpcs

Add a label parameter to the WalletController SendOutputs endpoint and
update rpcs that use it to allow optional provision of labels.

labels/labels.go

@@ -3,6 +3,31 @@
 // package to avoid dependency issues.
 package labels
 
+import (
+	"fmt"
+
+	"github.com/btcsuite/btcwallet/wtxmgr"
+)
+
 // External labels a transaction as user initiated via the api. This
 // label is only used when a custom user provided label is not given.
 const External = "external"
+
+// ValidateAPI returns the generic api label if the label provided is empty.
+// This allows us to label all transactions published by the api, even if
+// no label is provided. If a label is provided, it is validated against
+// the known restrictions.
+func ValidateAPI(label string) (string, error) {
+	if len(label) > wtxmgr.TxLabelLimit {
+		return "", fmt.Errorf("label length: %v exceeds "+
+			"limit of %v", len(label), wtxmgr.TxLabelLimit)
+	}
+
+	// If no label was provided by the user, add the generic user
+	// send label.
+	if len(label) == 0 {
+		return External, nil
+	}
+
+	return label, nil
+}

lnrpc/rpc.proto

@@ -1002,6 +1002,9 @@ message SendManyRequest {
     // A manual fee rate set in sat/byte that should be used when crafting the
     // transaction.
     int64 sat_per_byte = 5;
+
+    // An optional label for the transaction, limited to 500 characters.
+    string label = 6;
 }
 message SendManyResponse {
     // The id of the transaction
@@ -1029,6 +1032,9 @@ message SendCoinsRequest {
     address.
     */
     bool send_all = 6;
+
+    // An optional label for the transaction, limited to 500 characters.
+    string label = 7;
 }
 message SendCoinsResponse {
     // The transaction ID of the transaction

lnrpc/rpc.swagger.json

@@ -4230,6 +4230,10 @@
           "type": "boolean",
           "format": "boolean",
           "description": "If set, then the amount field will be ignored, and lnd will attempt to\nsend all the coins under control of the internal wallet to the specified\naddress."
+        },
+        "label": {
+          "type": "string",
+          "description": "An optional label for the transaction, limited to 500 characters."
         }
       }
     },

lnrpc/walletrpc/walletkit_server.go

@@ -311,6 +311,7 @@ func (w *WalletKit) SendOutputs(ctx context.Context,
 	// attempt to create this transaction.
 	tx, err := w.cfg.Wallet.SendOutputs(
 		outputsToCreate, chainfee.SatPerKWeight(req.SatPerKw),
+		labels.External,
 	)
 	if err != nil {
 		return nil, err

lnwallet/btcwallet/btcwallet.go

@@ -294,7 +294,7 @@ func (b *BtcWallet) IsOurAddress(a btcutil.Address) bool {
 //
 // This is a part of the WalletController interface.
 func (b *BtcWallet) SendOutputs(outputs []*wire.TxOut,
-	feeRate chainfee.SatPerKWeight) (*wire.MsgTx, error) {
+	feeRate chainfee.SatPerKWeight, label string) (*wire.MsgTx, error) {
 
 	// Convert our fee rate from sat/kw to sat/kb since it's required by
 	// SendOutputs.
@@ -304,7 +304,10 @@ func (b *BtcWallet) SendOutputs(outputs []*wire.TxOut,
 	if len(outputs) < 1 {
 		return nil, lnwallet.ErrNoOutputs
 	}
-	return b.wallet.SendOutputs(outputs, defaultAccount, 1, feeSatPerKB, "")
+
+	return b.wallet.SendOutputs(
+		outputs, defaultAccount, 1, feeSatPerKB, label,
+	)
 }
 
 // CreateSimpleTx creates a Bitcoin transaction paying to the specified

lnwallet/interface.go

@@ -174,7 +174,7 @@ type WalletController interface {
 	// This method also takes the target fee expressed in sat/kw that should
 	// be used when crafting the transaction.
 	SendOutputs(outputs []*wire.TxOut,
-		feeRate chainfee.SatPerKWeight) (*wire.MsgTx, error)
+		feeRate chainfee.SatPerKWeight, label string) (*wire.MsgTx, error)
 
 	// CreateSimpleTx creates a Bitcoin transaction paying to the specified
 	// outputs. The transaction is not broadcasted to the network. In the

lnwallet/interface_test.go

@@ -174,7 +174,9 @@ func sendCoins(t *testing.T, miner *rpctest.Harness,
 
 	t.Helper()
 
-	tx, err := sender.SendOutputs([]*wire.TxOut{output}, 2500)
+	tx, err := sender.SendOutputs(
+		[]*wire.TxOut{output}, 2500, labels.External,
+	)
 	if err != nil {
 		t.Fatalf("unable to send transaction: %v", err)
 	}
@@ -1220,7 +1222,9 @@ func testListTransactionDetails(miner *rpctest.Harness,
 		t.Fatalf("unable to make output script: %v", err)
 	}
 	burnOutput := wire.NewTxOut(outputAmt, outputScript)
-	burnTX, err := alice.SendOutputs([]*wire.TxOut{burnOutput}, 2500)
+	burnTX, err := alice.SendOutputs(
+		[]*wire.TxOut{burnOutput}, 2500, labels.External,
+	)
 	if err != nil {
 		t.Fatalf("unable to create burn tx: %v", err)
 	}
@@ -1493,7 +1497,9 @@ func testTransactionSubscriptions(miner *rpctest.Harness,
 		t.Fatalf("unable to make output script: %v", err)
 	}
 	burnOutput := wire.NewTxOut(outputAmt, outputScript)
-	tx, err := alice.SendOutputs([]*wire.TxOut{burnOutput}, 2500)
+	tx, err := alice.SendOutputs(
+		[]*wire.TxOut{burnOutput}, 2500, labels.External,
+	)
 	if err != nil {
 		t.Fatalf("unable to create burn tx: %v", err)
 	}
@@ -1684,7 +1690,9 @@ func newTx(t *testing.T, r *rpctest.Harness, pubKey *btcec.PublicKey,
 		Value:    btcutil.SatoshiPerBitcoin,
 		PkScript: keyScript,
 	}
-	tx, err := alice.SendOutputs([]*wire.TxOut{newOutput}, 2500)
+	tx, err := alice.SendOutputs(
+		[]*wire.TxOut{newOutput}, 2500, labels.External,
+	)
 	if err != nil {
 		t.Fatalf("unable to create output: %v", err)
 	}
@@ -1973,7 +1981,9 @@ func testSignOutputUsingTweaks(r *rpctest.Harness,
 			Value:    btcutil.SatoshiPerBitcoin,
 			PkScript: keyScript,
 		}
-		tx, err := alice.SendOutputs([]*wire.TxOut{newOutput}, 2500)
+		tx, err := alice.SendOutputs(
+			[]*wire.TxOut{newOutput}, 2500, labels.External,
+		)
 		if err != nil {
 			t.Fatalf("unable to create output: %v", err)
 		}
@@ -2095,7 +2105,9 @@ func testReorgWalletBalance(r *rpctest.Harness, w *lnwallet.LightningWallet,
 		Value:    1e8,
 		PkScript: script,
 	}
-	tx, err := w.SendOutputs([]*wire.TxOut{output}, 2500)
+	tx, err := w.SendOutputs(
+		[]*wire.TxOut{output}, 2500, labels.External,
+	)
 	if err != nil {
 		t.Fatalf("unable to send outputs: %v", err)
 	}
@@ -2476,7 +2488,7 @@ func testCreateSimpleTx(r *rpctest.Harness, w *lnwallet.LightningWallet,
 		// _very_ similar to the one we just created being sent. The
 		// only difference is that the dry run tx is not signed, and
 		// that the change output position might be different.
-		tx, sendErr := w.SendOutputs(outputs, feeRate)
+		tx, sendErr := w.SendOutputs(outputs, feeRate, labels.External)
 		switch {
 		case test.valid && sendErr != nil:
 			t.Fatalf("got unexpected error when sending tx: %v",

mock.go

@@ -281,7 +281,7 @@ func (*mockWalletController) IsOurAddress(a btcutil.Address) bool {
 }
 
 func (*mockWalletController) SendOutputs(outputs []*wire.TxOut,
-	_ chainfee.SatPerKWeight) (*wire.MsgTx, error) {
+	_ chainfee.SatPerKWeight, _ string) (*wire.MsgTx, error) {
 
 	return nil, nil
 }

rpcserver.go

@@ -44,6 +44,7 @@ import (
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/invoices"
 	"github.com/lightningnetwork/lnd/keychain"
+	"github.com/lightningnetwork/lnd/labels"
 	"github.com/lightningnetwork/lnd/lncfg"
 	"github.com/lightningnetwork/lnd/lnrpc"
 	"github.com/lightningnetwork/lnd/lnrpc/invoicesrpc"
@@ -924,14 +925,14 @@ func addrPairsToOutputs(addrPairs map[string]int64) ([]*wire.TxOut, error) {
 // more addresses specified in the passed payment map. The payment map maps an
 // address to a specified output value to be sent to that address.
 func (r *rpcServer) sendCoinsOnChain(paymentMap map[string]int64,
-	feeRate chainfee.SatPerKWeight) (*chainhash.Hash, error) {
+	feeRate chainfee.SatPerKWeight, label string) (*chainhash.Hash, error) {
 
 	outputs, err := addrPairsToOutputs(paymentMap)
 	if err != nil {
 		return nil, err
 	}
 
-	tx, err := r.server.cc.wallet.SendOutputs(outputs, feeRate)
+	tx, err := r.server.cc.wallet.SendOutputs(outputs, feeRate, label)
 	if err != nil {
 		return nil, err
 	}
@@ -1147,6 +1148,11 @@ func (r *rpcServer) SendCoins(ctx context.Context,
 		return nil, fmt.Errorf("cannot send coins to pubkeys")
 	}
 
+	label, err := labels.ValidateAPI(in.Label)
+	if err != nil {
+		return nil, err
+	}
+
 	var txid *chainhash.Hash
 
 	wallet := r.server.cc.wallet
@@ -1187,9 +1193,7 @@ func (r *rpcServer) SendCoins(ctx context.Context,
 		// As our sweep transaction was created, successfully, we'll
 		// now attempt to publish it, cancelling the sweep pkg to
 		// return all outputs if it fails.
-		err = wallet.PublishTransaction(
-			sweepTxPkg.SweepTx, "",
-		)
+		err = wallet.PublishTransaction(sweepTxPkg.SweepTx, label)
 		if err != nil {
 			sweepTxPkg.CancelSweepAttempt()
 
@@ -1207,7 +1211,9 @@ func (r *rpcServer) SendCoins(ctx context.Context,
 		// while we instruct the wallet to send this transaction.
 		paymentMap := map[string]int64{targetAddr.String(): in.Amount}
 		err := wallet.WithCoinSelectLock(func() error {
-			newTXID, err := r.sendCoinsOnChain(paymentMap, feePerKw)
+			newTXID, err := r.sendCoinsOnChain(
+				paymentMap, feePerKw, label,
+			)
 			if err != nil {
 				return err
 			}
@@ -1244,6 +1250,11 @@ func (r *rpcServer) SendMany(ctx context.Context,
 		return nil, err
 	}
 
+	label, err := labels.ValidateAPI(in.Label)
+	if err != nil {
+		return nil, err
+	}
+
 	rpcsLog.Infof("[sendmany] outputs=%v, sat/kw=%v",
 		spew.Sdump(in.AddrToAmount), int64(feePerKw))
 
@@ -1255,7 +1266,7 @@ func (r *rpcServer) SendMany(ctx context.Context,
 	wallet := r.server.cc.wallet
 	err = wallet.WithCoinSelectLock(func() error {
 		sendManyTXID, err := r.sendCoinsOnChain(
-			in.AddrToAmount, feePerKw,
+			in.AddrToAmount, feePerKw, label,
 		)
 		if err != nil {
 			return err