feat: TX collateral return support (#604)

This adds support for returning the collateral return value (if any)
decoded from the transaction body

Fixes #340

ledger/allegra.go

@@ -158,6 +158,10 @@ func (t AllegraTransaction) ReferenceInputs() []TransactionInput {
 	return t.Body.ReferenceInputs()
 }
 
+func (t AllegraTransaction) CollateralReturn() TransactionOutput {
+	return t.Body.CollateralReturn()
+}
+
 func (t AllegraTransaction) Metadata() *cbor.Value {
 	return t.TxMetadata
 }

ledger/alonzo.go

@@ -260,6 +260,10 @@ func (t AlonzoTransaction) ReferenceInputs() []TransactionInput {
 	return t.Body.ReferenceInputs()
 }
 
+func (t AlonzoTransaction) CollateralReturn() TransactionOutput {
+	return t.Body.CollateralReturn()
+}
+
 func (t AlonzoTransaction) Metadata() *cbor.Value {
 	return t.TxMetadata
 }

ledger/babbage.go

@@ -181,9 +181,9 @@ type BabbageTransactionBody struct {
 		ProtocolParamUpdates map[Blake2b224]BabbageProtocolParameterUpdate
 		Epoch                uint64
 	} `cbor:"6,keyasint,omitempty"`
-	CollateralReturn  BabbageTransactionOutput  `cbor:"16,keyasint,omitempty"`
-	TotalCollateral   uint64                    `cbor:"17,keyasint,omitempty"`
-	TxReferenceInputs []ShelleyTransactionInput `cbor:"18,keyasint,omitempty"`
+	TxCollateralReturn *BabbageTransactionOutput `cbor:"16,keyasint,omitempty"`
+	TotalCollateral    uint64                    `cbor:"17,keyasint,omitempty"`
+	TxReferenceInputs  []ShelleyTransactionInput `cbor:"18,keyasint,omitempty"`
 }
 
 func (b *BabbageTransactionBody) UnmarshalCBOR(cborData []byte) error {
@@ -208,6 +208,10 @@ func (b *BabbageTransactionBody) ReferenceInputs() []TransactionInput {
 	return ret
 }
 
+func (b *BabbageTransactionBody) CollateralReturn() TransactionOutput {
+	return b.TxCollateralReturn
+}
+
 func (b *BabbageTransactionBody) Utxorpc() *utxorpc.Tx {
 	var txi, txri []*utxorpc.TxInput
 	var txo []*utxorpc.TxOutput
@@ -430,6 +434,10 @@ func (t BabbageTransaction) ReferenceInputs() []TransactionInput {
 	return t.Body.ReferenceInputs()
 }
 
+func (t BabbageTransaction) CollateralReturn() TransactionOutput {
+	return t.Body.CollateralReturn()
+}
+
 func (t BabbageTransaction) Metadata() *cbor.Value {
 	return t.TxMetadata
 }

ledger/byron.go

@@ -175,6 +175,11 @@ func (t *ByronTransaction) ReferenceInputs() []TransactionInput {
 	return nil
 }
 
+func (t *ByronTransaction) CollateralReturn() TransactionOutput {
+	// No collateral in Byron
+	return nil
+}
+
 func (t *ByronTransaction) Metadata() *cbor.Value {
 	return t.Attributes
 }

ledger/conway.go

@@ -164,6 +164,10 @@ func (t ConwayTransaction) ReferenceInputs() []TransactionInput {
 	return t.Body.ReferenceInputs()
 }
 
+func (t ConwayTransaction) CollateralReturn() TransactionOutput {
+	return t.Body.CollateralReturn()
+}
+
 func (t ConwayTransaction) Metadata() *cbor.Value {
 	return t.TxMetadata
 }

ledger/mary.go

@@ -175,6 +175,10 @@ func (t MaryTransaction) ReferenceInputs() []TransactionInput {
 	return t.Body.ReferenceInputs()
 }
 
+func (t MaryTransaction) CollateralReturn() TransactionOutput {
+	return t.Body.CollateralReturn()
+}
+
 func (t MaryTransaction) Metadata() *cbor.Value {
 	return t.TxMetadata
 }

ledger/shelley.go

@@ -221,6 +221,11 @@ func (b *ShelleyTransactionBody) ReferenceInputs() []TransactionInput {
 	return []TransactionInput{}
 }
 
+func (b *ShelleyTransactionBody) CollateralReturn() TransactionOutput {
+	// No collateral in Shelley
+	return nil
+}
+
 func (b *ShelleyTransactionBody) Utxorpc() *utxorpc.Tx {
 	var txi []*utxorpc.TxInput
 	var txo []*utxorpc.TxOutput
@@ -359,6 +364,10 @@ func (t ShelleyTransaction) ReferenceInputs() []TransactionInput {
 	return t.Body.ReferenceInputs()
 }
 
+func (t ShelleyTransaction) CollateralReturn() TransactionOutput {
+	return t.Body.CollateralReturn()
+}
+
 func (t ShelleyTransaction) Metadata() *cbor.Value {
 	return t.TxMetadata
 }

ledger/tx.go

@@ -40,6 +40,7 @@ type TransactionBody interface {
 	TTL() uint64
 	ReferenceInputs() []TransactionInput
 	Utxorpc() *utxorpc.Tx
+	CollateralReturn() TransactionOutput
 }
 
 type TransactionInput interface {