multi: remove AltLeaves from vInputs

Because we retrieve AltLeaves from the proof during anchor input
validation, we don't need to store them in the vInputs struct. This commit
removes the AltLeaves field from the vInputs struct and the associated
methods.

Author: gijswijs

tapfreighter/fund.go

@@ -460,16 +460,6 @@ func createAndSetInput(vPkt *tappsbt.VPacket, idx int,
 	}
 	vPkt.SetInputAsset(idx, assetInput.Asset)
 
-	inputAltLeaves, err := assetInput.Commitment.FetchAltLeaves()
-	if err != nil {
-		return fmt.Errorf("cannot fetch alt leaves from input: %w", err)
-	}
-
-	err = vPkt.Inputs[idx].SetAltLeaves(inputAltLeaves)
-	if err != nil {
-		return fmt.Errorf("cannot set alt leaves on vInput: %w", err)
-	}
-
 	return nil
 }
 

tapfreighter/wallet.go

@@ -278,8 +278,7 @@ func (f *AssetWallet) FundAddressSend(ctx context.Context,
 func createPassivePacket(passiveAsset *asset.Asset,
 	activePackets []*tappsbt.VPacket, anchorOutputIndex uint32,
 	anchorOutputInternalKey keychain.KeyDescriptor, prevOut wire.OutPoint,
-	inputProof *proof.Proof,
-	inputAltLeaves []*asset.Asset) (*tappsbt.VPacket, error) {
+	inputProof *proof.Proof) (*tappsbt.VPacket, error) {
 
 	if len(activePackets) == 0 {
 		return nil, errors.New("no active packets provided")
@@ -299,12 +298,8 @@ func createPassivePacket(passiveAsset *asset.Asset,
 			SighashType: txscript.SigHashDefault,
 		},
 	}
-	err := vInput.SetAltLeaves(inputAltLeaves)
-	if err != nil {
-		return nil, err
-	}
 
-	err = tapsend.ValidateVPacketVersions(activePackets)
+	err := tapsend.ValidateVPacketVersions(activePackets)
 	if err != nil {
 		return nil, err
 	}
@@ -958,7 +953,7 @@ func CreatePassiveAssets(ctx context.Context, keyRing KeyRing,
 		// removing the active assets. But we don't want to count the
 		// alt leaves as "assets" in this context, so we'll trim them
 		// out.
-		trimmedPassives, altLeaves, err := commitment.TrimAltLeaves(
+		trimmedPassives, _, err := commitment.TrimAltLeaves(
 			passiveCommitments,
 		)
 		if err != nil {
@@ -994,7 +989,7 @@ func CreatePassiveAssets(ctx context.Context, keyRing KeyRing,
 			passivePacket, err := createPassivePacket(
 				passiveAsset, activePackets,
 				anchorOutIdx, *anchorOutDesc, prevID.OutPoint,
-				inputProof, altLeaves,
+				inputProof,
 			)
 			if err != nil {
 				return nil, fmt.Errorf("unable to create "+

tappsbt/decode.go

@@ -173,9 +173,6 @@ func (i *VInput) decode(pIn psbt.PInput) error {
 	}, {
 		key:     PsbtKeyTypeInputTapAssetProof,
 		decoder: proofDecoder(&i.Proof),
-	}, {
-		key:     PsbtKeyTypeInputAltLeaves,
-		decoder: altLeavesDecoder(&i.AltLeaves),
 	}}
 
 	for idx := range mapping {

tappsbt/decode_test.go

@@ -255,7 +255,6 @@ func TestEncodingDecoding(t *testing.T) {
 				firstLeaf, secondLeaf,
 			}
 
-			pkt.Inputs[0].AltLeaves = asset.CopyAltLeaves(altLeaves)
 			pkt.Outputs[0].AltLeaves = asset.CopyAltLeaves(
 				altLeaves,
 			)
@@ -279,7 +278,6 @@ func TestEncodingDecoding(t *testing.T) {
 				altLeaves[idx] = asset.RandAltLeaf(t)
 			}
 
-			pkt.Inputs[0].AltLeaves = altLeaves
 			pkt.Outputs[0].AltLeaves = altLeaves
 			pkt.Outputs[1].AltLeaves = altLeaves
 

tappsbt/encode.go

@@ -183,9 +183,6 @@ func (i *VInput) encode() (psbt.PInput, error) {
 		{
 			key:     PsbtKeyTypeInputTapAssetProof,
 			encoder: proofEncoder(i.Proof),
-		}, {
-			key:     PsbtKeyTypeInputAltLeaves,
-			encoder: altLeavesEncoder(i.AltLeaves),
 		},
 	}
 

tappsbt/interface.go

@@ -43,7 +43,6 @@ var (
 	PsbtKeyTypeInputTapAnchorTapscriptSibling             = []byte{0x78}
 	PsbtKeyTypeInputTapAsset                              = []byte{0x79}
 	PsbtKeyTypeInputTapAssetProof                         = []byte{0x7a}
-	PsbtKeyTypeInputAltLeaves                             = []byte{0x7b}
 
 	PsbtKeyTypeOutputTapType                               = []byte{0x70}
 	PsbtKeyTypeOutputTapIsInteractive                      = []byte{0x71}
@@ -394,12 +393,6 @@ type VInput struct {
 	// Proof is a transition proof that proves the asset being spent was
 	// committed to in the anchor transaction above.
 	Proof *proof.Proof
-
-	// AltLeaves represent data used to construct an Asset commitment, that
-	// will be inserted in the input anchor Tap commitment. These
-	// data-carrying leaves are used for a purpose distinct from
-	// representing individual Taproot Assets.
-	AltLeaves []asset.AltLeaf[asset.Asset]
 }
 
 // Copy creates a deep copy of the VInput.
@@ -417,8 +410,7 @@ func (i *VInput) Copy() *VInput {
 		// We never expect the individual fields of the proof to change
 		// while it is assigned to a virtual input. So not deep copying
 		// it here is fine.
-		Proof:     i.Proof,
-		AltLeaves: asset.CopyAltLeaves(i.AltLeaves),
+		Proof: i.Proof,
 	}
 }
 
@@ -427,27 +419,6 @@ func (i *VInput) Asset() *asset.Asset {
 	return i.asset
 }
 
-// SetAltLeaves asserts that a set of AltLeaves are valid, and updates a VInput
-// to set the AltLeaves. Setting the input's AltLeaves twice is disallowed.
-func (i *VInput) SetAltLeaves(altLeafAssets []*asset.Asset) error {
-	// AltLeaves can be set exactly once on a VInput.
-	if len(i.AltLeaves) != 0 {
-		return fmt.Errorf("%w: input", ErrAltLeavesAlreadySet)
-	}
-
-	// Each asset must be a valid AltLeaf, and the set of AltLeaves must be
-	// valid, by not having overlapping keys in the AltCommitment.
-	altLeaves := asset.ToAltLeaves(altLeafAssets)
-	err := asset.ValidAltLeaves(altLeaves)
-	if err != nil {
-		return err
-	}
-
-	i.AltLeaves = asset.CopyAltLeaves(altLeaves)
-
-	return nil
-}
-
 // serializeScriptKey serializes the input asset's script key as the PSBT
 // derivation information on the virtual input.
 func (i *VInput) serializeScriptKey(key asset.ScriptKey, coinType uint32) {

tappsbt/mock.go

@@ -173,10 +173,8 @@ func RandPacket(t testing.TB, setVersion, altLeaves bool) *VPacket {
 	}
 
 	if altLeaves {
-		inputLeaves := asset.RandAltLeaves(t, true)
 		output1Leaves := asset.RandAltLeaves(t, true)
 		output2Leaves := asset.RandAltLeaves(t, true)
-		randVInput.AltLeaves = asset.ToAltLeaves(inputLeaves)
 		randVOutput1.AltLeaves = asset.ToAltLeaves(output1Leaves)
 		randVOutput2.AltLeaves = asset.ToAltLeaves(output2Leaves)
 	}
@@ -308,22 +306,6 @@ func NewTestFromVInput(t testing.TB, i *VInput) *TestVInput {
 		ti.Proof = proof.NewTestFromProof(t, i.Proof)
 	}
 
-	if len(i.AltLeaves) > 0 {
-		// Assert that the concrete type of AltLeaf is supported.
-		require.IsTypef(
-			t, &asset.Asset{}, i.AltLeaves[0],
-			"AltLeaves must be of type *asset.Asset",
-		)
-
-		ti.AltLeaves = make([]*asset.TestAsset, 0, len(i.AltLeaves))
-		for idx := range i.AltLeaves {
-			leaf := i.AltLeaves[idx].(*asset.Asset)
-			ti.AltLeaves = append(
-				ti.AltLeaves, asset.NewTestFromAsset(t, leaf),
-			)
-		}
-	}
-
 	return ti
 }
 
@@ -336,7 +318,6 @@ type TestVInput struct {
 	Anchor            *TestAnchor              `json:"anchor"`
 	Asset             *asset.TestAsset         `json:"asset"`
 	Proof             *proof.TestProof         `json:"proof"`
-	AltLeaves         []*asset.TestAsset       `json:"alt_leaves"`
 }
 
 func (ti *TestVInput) ToVInput(t testing.TB) *VInput {
@@ -379,15 +360,6 @@ func (ti *TestVInput) ToVInput(t testing.TB) *VInput {
 		vi.Proof = ti.Proof.ToProof(t)
 	}
 
-	if len(ti.AltLeaves) > 0 {
-		vi.AltLeaves = make(
-			[]asset.AltLeaf[asset.Asset], len(ti.AltLeaves),
-		)
-		for idx, leaf := range ti.AltLeaves {
-			vi.AltLeaves[idx] = leaf.ToAsset(t)
-		}
-	}
-
 	return vi
 }