tapfreighter: accept fee rate arg for transfers

In this commit, we add support for overriding the fee estimator and
providing a target fee rate to the freighter when performing a transfer.
This only applies to sends to addresses and not via interactive vPSBTs.

Author: jharveyb

tapfreighter/chain_porter.go

@@ -20,6 +20,7 @@ import (
 	"github.com/lightninglabs/taproot-assets/tappsbt"
 	"github.com/lightninglabs/taproot-assets/tapscript"
 	"github.com/lightningnetwork/lnd/chainntnfs"
+	"github.com/lightningnetwork/lnd/lnwallet/chainfee"
 )
 
 // ChainPorterConfig is the main config for the chain porter.
@@ -880,14 +881,32 @@ func (p *ChainPorter) stateStep(currentPkg sendPackage) (*sendPackage, error) {
 		// Submit the template PSBT to the wallet for funding.
 		//
 		// TODO(roasbeef): unlock the input UTXOs of things fail
-		feeRate, err := p.cfg.ChainBridge.EstimateFee(
-			ctx, tapscript.SendConfTarget,
+		var (
+			feeRate chainfee.SatPerKWeight
+			err     error
 		)
-		if err != nil {
-			return nil, fmt.Errorf("unable to estimate fee: %w",
-				err)
+
+		// First, use a manual fee rate if specified by the parcel.
+		// TODO(jhb): Support PSBT flow / PreSignedParcels
+		addrParcel, ok := currentPkg.Parcel.(*AddressParcel)
+		switch {
+		case ok && addrParcel.transferFeeRate != nil:
+			feeRate = *addrParcel.transferFeeRate
+			log.Infof("sending with manual fee rate")
+
+		default:
+			feeRate, err = p.cfg.ChainBridge.EstimateFee(
+				ctx, tapscript.SendConfTarget,
+			)
+			if err != nil {
+				return nil, fmt.Errorf("unable to estimate "+
+					"fee: %w", err)
+			}
 		}
 
+		readableFeeRate := feeRate.FeePerKVByte().String()
+		log.Infof("sending with fee rate: %v", readableFeeRate)
+
 		vPacket := currentPkg.VirtualPacket
 		firstRecipient, err := vPacket.FirstNonSplitRootOutput()
 		if err != nil {

tapfreighter/parcel.go

@@ -17,6 +17,7 @@ import (
 	"github.com/lightninglabs/taproot-assets/tappsbt"
 	"github.com/lightningnetwork/lnd/chainntnfs"
 	"github.com/lightningnetwork/lnd/keychain"
+	"github.com/lightningnetwork/lnd/lnwallet/chainfee"
 )
 
 // SendState is an enum that describes the current state of a pending outbound
@@ -130,20 +131,27 @@ type AddressParcel struct {
 	// destAddrs is the list of address that should be used to satisfy the
 	// transfer.
 	destAddrs []*address.Tap
+
+	// transferFeeRate is an optional manually-set feerate specified when
+	// requesting an asset transfer.
+	transferFeeRate *chainfee.SatPerKWeight
 }
 
 // A compile-time assertion to ensure AddressParcel implements the parcel
 // interface.
 var _ Parcel = (*AddressParcel)(nil)
 
 // NewAddressParcel creates a new AddressParcel.
-func NewAddressParcel(destAddrs ...*address.Tap) *AddressParcel {
+func NewAddressParcel(feeRate *chainfee.SatPerKWeight,
+	destAddrs ...*address.Tap) *AddressParcel {
+
 	return &AddressParcel{
 		parcelKit: &parcelKit{
 			respChan: make(chan *OutboundParcel, 1),
 			errChan:  make(chan error, 1),
 		},
-		destAddrs: destAddrs,
+		destAddrs:       destAddrs,
+		transferFeeRate: feeRate,
 	}
 }
 

tapfreighter/wallet.go

@@ -1442,6 +1442,7 @@ func (f *AssetWallet) AnchorVirtualTransactions(ctx context.Context,
 		return nil, fmt.Errorf("unable to get on-chain fees for psbt: "+
 			"%w", err)
 	}
+	log.Infof("PSBT absolute fee: %d sats", chainFees)
 
 	err = psbt.MaybeFinalizeAll(signedPsbt)
 	if err != nil {