multi: add asset specifier field to FundingDescriptor struct

This commit replaces the asset ID and asset group public key fields in
the `FundingDescriptor` struct with an asset specifier field.

Author: ffranr

rpcserver.go

@@ -3202,11 +3202,14 @@ func (r *rpcServer) BurnAsset(ctx context.Context,
 		"burn_amount=%d)", assetID[:], serializedGroupKey,
 		in.AmountToBurn)
 
+	assetSpecifier := asset.NewSpecifierOptionalGroupPubKey(
+		assetID, groupKey,
+	)
+
 	fundResp, err := r.cfg.AssetWallet.FundBurn(
 		ctx, &tapsend.FundingDescriptor{
-			ID:       assetID,
-			GroupKey: groupKey,
-			Amount:   in.AmountToBurn,
+			AssetSpecifier: assetSpecifier,
+			Amount:         in.AmountToBurn,
 		},
 	)
 	if err != nil {

tapfreighter/wallet.go

@@ -362,12 +362,20 @@ func (f *AssetWallet) FundPacket(ctx context.Context,
 		return nil, address.ErrMismatchedHRP
 	}
 
+	// Extract the asset ID and group key from the funding descriptor.
+	assetId := fundDesc.AssetSpecifier.UnwrapIdToPtr()
+	if assetId == nil {
+		return nil, fmt.Errorf("unable to unwrap asset ID")
+	}
+
+	groupKey := fundDesc.AssetSpecifier.UnwrapGroupKeyToPtr()
+
 	// We need to find a commitment that has enough assets to satisfy this
 	// send request. We'll map the address to a set of constraints, so we
 	// can use that to do Taproot asset coin selection.
 	constraints := CommitmentConstraints{
-		GroupKey:            fundDesc.GroupKey,
-		AssetID:             &fundDesc.ID,
+		GroupKey:            groupKey,
+		AssetID:             assetId,
 		MinAmt:              fundDesc.Amount,
 		Bip86ScriptKeysOnly: true,
 	}
@@ -396,12 +404,20 @@ func (f *AssetWallet) FundPacket(ctx context.Context,
 func (f *AssetWallet) FundBurn(ctx context.Context,
 	fundDesc *tapsend.FundingDescriptor) (*FundedVPacket, error) {
 
+	// Extract the asset ID and group key from the funding descriptor.
+	assetId, err := fundDesc.AssetSpecifier.UnwrapIdOrErr()
+	if err != nil {
+		return nil, err
+	}
+
+	groupKey := fundDesc.AssetSpecifier.UnwrapGroupKeyToPtr()
+
 	// We need to find a commitment that has enough assets to satisfy this
 	// send request. We'll map the address to a set of constraints, so we
 	// can use that to do Taproot asset coin selection.
 	constraints := CommitmentConstraints{
-		GroupKey: fundDesc.GroupKey,
-		AssetID:  &fundDesc.ID,
+		GroupKey: groupKey,
+		AssetID:  assetId,
 		MinAmt:   fundDesc.Amount,
 	}
 	selectedCommitments, err := f.cfg.CoinSelector.SelectCoins(
@@ -433,7 +449,7 @@ func (f *AssetWallet) FundBurn(ctx context.Context,
 
 	activeAssets := fn.Filter(
 		selectedCommitments, func(c *AnchoredCommitment) bool {
-			return c.Asset.ID() == fundDesc.ID
+			return c.Asset.ID() == assetId
 		},
 	)
 
@@ -467,7 +483,7 @@ func (f *AssetWallet) FundBurn(ctx context.Context,
 	vPkt := &tappsbt.VPacket{
 		Inputs: []*tappsbt.VInput{{
 			PrevID: asset.PrevID{
-				ID: fundDesc.ID,
+				ID: assetId,
 			},
 		}},
 		Outputs: []*tappsbt.VOutput{{
@@ -554,8 +570,13 @@ func (f *AssetWallet) fundPacketWithInputs(ctx context.Context,
 	fundDesc *tapsend.FundingDescriptor, vPkt *tappsbt.VPacket,
 	selectedCommitments []*AnchoredCommitment) (*FundedVPacket, error) {
 
+	assetId, err := fundDesc.AssetSpecifier.UnwrapIdOrErr()
+	if err != nil {
+		return nil, err
+	}
+
 	log.Infof("Selected %v asset inputs for send of %d to %x",
-		len(selectedCommitments), fundDesc.Amount, fundDesc.ID[:])
+		len(selectedCommitments), fundDesc.Amount, assetId[:])
 
 	assetType := selectedCommitments[0].Asset.Type
 

tapsend/send.go

@@ -159,11 +159,8 @@ type AssetGroupQuerier interface {
 // verify input assets in order to send to a specific recipient. It is a subset
 // of the information contained in a Taproot Asset address.
 type FundingDescriptor struct {
-	// ID is the asset ID of the asset being transferred.
-	ID asset.ID
-
-	// GroupKey is the optional group key of the asset to transfer.
-	GroupKey *btcec.PublicKey
+	// AssetSpecifier is the asset specifier.
+	AssetSpecifier asset.Specifier
 
 	// Amount is the amount of the asset to transfer.
 	Amount uint64
@@ -172,12 +169,7 @@ type FundingDescriptor struct {
 // TapCommitmentKey is the key that maps to the root commitment for the asset
 // group specified by a recipient descriptor.
 func (r *FundingDescriptor) TapCommitmentKey() [32]byte {
-	assetSpecifier := asset.NewIdSpecifier(r.ID)
-	if r.GroupKey != nil {
-		assetSpecifier = asset.NewSpecifier(r.ID, *r.GroupKey)
-	}
-
-	return asset.TapCommitmentKey(assetSpecifier)
+	return asset.TapCommitmentKey(r.AssetSpecifier)
 }
 
 // DescribeRecipients extracts the recipient descriptors from a Taproot Asset
@@ -204,9 +196,12 @@ func DescribeRecipients(ctx context.Context, vPkt *tappsbt.VPacket,
 		return nil, fmt.Errorf("unable to query asset group: %w", err)
 	}
 
+	assetSpecifier := asset.NewSpecifierOptionalGroupPubKey(
+		firstInput.PrevID.ID, groupPubKey,
+	)
+
 	desc := &FundingDescriptor{
-		ID:       firstInput.PrevID.ID,
-		GroupKey: groupPubKey,
+		AssetSpecifier: assetSpecifier,
 	}
 	for idx := range vPkt.Outputs {
 		desc.Amount += vPkt.Outputs[idx].Amount
@@ -223,9 +218,13 @@ func DescribeAddrs(addrs []*address.Tap) (*FundingDescriptor, error) {
 	}
 
 	firstAddr := addrs[0]
+
+	assetSpecifier := asset.NewSpecifierOptionalGroupPubKey(
+		firstAddr.AssetID, firstAddr.GroupKey,
+	)
+
 	desc := &FundingDescriptor{
-		ID:       firstAddr.AssetID,
-		GroupKey: firstAddr.GroupKey,
+		AssetSpecifier: assetSpecifier,
 	}
 	for idx := range addrs {
 		desc.Amount += addrs[idx].Amount
@@ -251,10 +250,18 @@ func AssetFromTapCommitment(tapCommitment *commitment.TapCommitment,
 			ErrMissingInputAsset)
 	}
 
+	// Determine whether issuance is disabled for the asset.
+	issuanceDisabled := !desc.AssetSpecifier.HasGroupPubKey()
+
+	assetId, err := desc.AssetSpecifier.UnwrapIdOrErr()
+	if err != nil {
+		return nil, err
+	}
+
 	// The asset tree must have a non-empty Asset at the location
 	// specified by the sender's script key.
 	assetCommitmentKey := asset.AssetCommitmentKey(
-		desc.ID, &inputScriptKey, desc.GroupKey == nil,
+		assetId, &inputScriptKey, issuanceDisabled,
 	)
 	inputAsset, ok := assetCommitment.Asset(assetCommitmentKey)
 	if !ok {

tapsend/send_test.go

@@ -1810,10 +1810,13 @@ func TestAddressValidInput(t *testing.T) {
 }
 
 func addrToFundDesc(addr address.Tap) *tapsend.FundingDescriptor {
+	assetSpecifier := asset.NewSpecifierOptionalGroupPubKey(
+		addr.AssetID, addr.GroupKey,
+	)
+
 	return &tapsend.FundingDescriptor{
-		ID:       addr.AssetID,
-		GroupKey: addr.GroupKey,
-		Amount:   addr.Amount,
+		AssetSpecifier: assetSpecifier,
+		Amount:         addr.Amount,
 	}
 }
 
@@ -2419,7 +2422,7 @@ func TestValidateAnchorOutputs(t *testing.T) {
 	vOutCommitmentProof := proof.CommitmentProof{
 		Proof: commitment.Proof{
 			TaprootAssetProof: commitment.
-				TaprootAssetProof{
+			TaprootAssetProof{
 				Version: asset1Commitment.Version,
 			},
 		},