feat: TX required signers attribute (#630)

This adds a method to retrieve the required signers for a TX

Fixes #339

ledger/allegra.go

@@ -178,6 +178,10 @@ func (t AllegraTransaction) Withdrawals() map[*Address]uint64 {
 	return t.Body.Withdrawals()
 }
 
+func (t AllegraTransaction) RequiredSigners() []Blake2b224 {
+	return t.Body.RequiredSigners()
+}
+
 func (t AllegraTransaction) VotingProcedures() VotingProcedures {
 	return t.Body.VotingProcedures()
 }

ledger/alonzo.go

@@ -128,10 +128,10 @@ type AlonzoTransactionBody struct {
 		ProtocolParamUpdates map[Blake2b224]AlonzoProtocolParameterUpdate
 		Epoch                uint64
 	} `cbor:"6,keyasint,omitempty"`
-	ScriptDataHash  Blake2b256                `cbor:"11,keyasint,omitempty"`
-	TxCollateral    []ShelleyTransactionInput `cbor:"13,keyasint,omitempty"`
-	RequiredSigners []Blake2b224              `cbor:"14,keyasint,omitempty"`
-	NetworkId       uint8                     `cbor:"15,keyasint,omitempty"`
+	ScriptDataHash    Blake2b256                `cbor:"11,keyasint,omitempty"`
+	TxCollateral      []ShelleyTransactionInput `cbor:"13,keyasint,omitempty"`
+	TxRequiredSigners []Blake2b224              `cbor:"14,keyasint,omitempty"`
+	NetworkId         uint8                     `cbor:"15,keyasint,omitempty"`
 }
 
 func (b *AlonzoTransactionBody) UnmarshalCBOR(cborData []byte) error {
@@ -155,6 +155,10 @@ func (b *AlonzoTransactionBody) Collateral() []TransactionInput {
 	return ret
 }
 
+func (b *AlonzoTransactionBody) RequiredSigners() []Blake2b224 {
+	return b.TxRequiredSigners[:]
+}
+
 type AlonzoTransactionOutput struct {
 	cbor.StructAsArray
 	cbor.DecodeStoreCbor
@@ -288,6 +292,10 @@ func (t AlonzoTransaction) Withdrawals() map[*Address]uint64 {
 	return t.Body.Withdrawals()
 }
 
+func (t AlonzoTransaction) RequiredSigners() []Blake2b224 {
+	return t.Body.RequiredSigners()
+}
+
 func (t AlonzoTransaction) VotingProcedures() VotingProcedures {
 	return t.Body.VotingProcedures()
 }

ledger/babbage.go

@@ -468,6 +468,10 @@ func (t BabbageTransaction) VotingProcedures() VotingProcedures {
 	return t.Body.VotingProcedures()
 }
 
+func (t BabbageTransaction) RequiredSigners() []Blake2b224 {
+	return t.Body.RequiredSigners()
+}
+
 func (t BabbageTransaction) ProposalProcedures() []ProposalProcedure {
 	return t.Body.ProposalProcedures()
 }

ledger/byron.go

@@ -200,6 +200,11 @@ func (t *ByronTransaction) Withdrawals() map[*Address]uint64 {
 	return nil
 }
 
+func (t *ByronTransaction) RequiredSigners() []Blake2b224 {
+	// No required signers in Byron
+	return nil
+}
+
 func (t *ByronTransaction) VotingProcedures() VotingProcedures {
 	// No voting procedures in Byron
 	return nil

ledger/conway.go

@@ -369,6 +369,10 @@ func (t ConwayTransaction) Withdrawals() map[*Address]uint64 {
 	return t.Body.Withdrawals()
 }
 
+func (t ConwayTransaction) RequiredSigners() []Blake2b224 {
+	return t.Body.RequiredSigners()
+}
+
 func (t ConwayTransaction) VotingProcedures() VotingProcedures {
 	return t.Body.VotingProcedures()
 }

ledger/mary.go

@@ -195,6 +195,10 @@ func (t MaryTransaction) Withdrawals() map[*Address]uint64 {
 	return t.Body.Withdrawals()
 }
 
+func (t MaryTransaction) RequiredSigners() []Blake2b224 {
+	return t.Body.RequiredSigners()
+}
+
 func (t MaryTransaction) VotingProcedures() VotingProcedures {
 	return t.Body.VotingProcedures()
 }

ledger/shelley.go

@@ -244,6 +244,11 @@ func (b *ShelleyTransactionBody) Withdrawals() map[*Address]uint64 {
 	return b.TxWithdrawals
 }
 
+func (b *ShelleyTransactionBody) RequiredSigners() []Blake2b224 {
+	// No required signers in Shelley
+	return nil
+}
+
 func (t *ShelleyTransactionBody) VotingProcedures() VotingProcedures {
 	// No voting procedures in Shelley
 	return nil
@@ -412,6 +417,10 @@ func (t ShelleyTransaction) Withdrawals() map[*Address]uint64 {
 	return t.Body.Withdrawals()
 }
 
+func (t ShelleyTransaction) RequiredSigners() []Blake2b224 {
+	return t.Body.RequiredSigners()
+}
+
 func (t ShelleyTransaction) VotingProcedures() VotingProcedures {
 	return t.Body.VotingProcedures()
 }

ledger/tx.go

@@ -46,6 +46,7 @@ type TransactionBody interface {
 	TotalCollateral() uint64
 	Certificates() []Certificate
 	Withdrawals() map[*Address]uint64
+	RequiredSigners() []Blake2b224
 	VotingProcedures() VotingProcedures
 	ProposalProcedures() []ProposalProcedure
 	Utxorpc() *utxorpc.Tx