fix: prevent Conway TX inputs from being decoded as Shelley TX input (#840)

Conway-era TX inputs using CBOR tag 258 (sets) could be implicitly
decoded by earlier eras, but this doesn't match the behavior of
cardano-node. We explicitly prevent this from happening to allow proper
identification of TX types

Author: agaffney

cbor/decode.go

@@ -129,7 +129,6 @@ func DecodeGeneric(cborData []byte, dest interface{}) error {
 		// destination object
 		if valueDest.Kind() != reflect.Pointer ||
 			valueDest.Elem().Kind() != reflect.Struct {
-			decodeGenericTypeCacheMutex.Unlock()
 			return fmt.Errorf("destination must be a pointer to a struct")
 		}
 		destTypeFields := []reflect.StructField{}

ledger/conway/conway.go

@@ -199,8 +199,27 @@ func (t *ConwayTransactionWitnessSet) UnmarshalCBOR(cborData []byte) error {
 	return t.UnmarshalCbor(cborData, t)
 }
 
+type ConwayTransactionInputSet struct {
+	items []shelley.ShelleyTransactionInput
+}
+
+func (s *ConwayTransactionInputSet) UnmarshalCBOR(data []byte) error {
+	// This overrides the Shelley behavior that explicitly disallowed tag-wrapped sets
+	var tmpData []shelley.ShelleyTransactionInput
+	if _, err := cbor.Decode(data, &tmpData); err != nil {
+		return err
+	}
+	s.items = tmpData
+	return nil
+}
+
+func (s *ConwayTransactionInputSet) Items() []shelley.ShelleyTransactionInput {
+	return s.items
+}
+
 type ConwayTransactionBody struct {
 	babbage.BabbageTransactionBody
+	TxInputs               ConwayTransactionInputSet  `cbor:"0,keyasint,omitempty"`
 	TxVotingProcedures     common.VotingProcedures    `cbor:"19,keyasint,omitempty"`
 	TxProposalProcedures   []common.ProposalProcedure `cbor:"20,keyasint,omitempty"`
 	TxCurrentTreasuryValue int64                      `cbor:"21,keyasint,omitempty"`
@@ -211,6 +230,14 @@ func (b *ConwayTransactionBody) UnmarshalCBOR(cborData []byte) error {
 	return b.UnmarshalCbor(cborData, b)
 }
 
+func (b *ConwayTransactionBody) Inputs() []common.TransactionInput {
+	ret := []common.TransactionInput{}
+	for _, input := range b.TxInputs.Items() {
+		ret = append(ret, input)
+	}
+	return ret
+}
+
 func (b *ConwayTransactionBody) ProtocolParameterUpdates() (uint64, map[common.Blake2b224]common.ProtocolParameterUpdate) {
 	updateMap := make(map[common.Blake2b224]common.ProtocolParameterUpdate)
 	for k, v := range b.Update.ProtocolParamUpdates {

ledger/shelley/shelley.go

@@ -193,7 +193,7 @@ func (h *ShelleyBlockHeader) Era() common.Era {
 type ShelleyTransactionBody struct {
 	cbor.DecodeStoreCbor
 	hash           string
-	TxInputs       []ShelleyTransactionInput   `cbor:"0,keyasint,omitempty"`
+	TxInputs       ShelleyTransactionInputSet  `cbor:"0,keyasint,omitempty"`
 	TxOutputs      []ShelleyTransactionOutput  `cbor:"1,keyasint,omitempty"`
 	TxFee          uint64                      `cbor:"2,keyasint,omitempty"`
 	Ttl            uint64                      `cbor:"3,keyasint,omitempty"`
@@ -221,7 +221,7 @@ func (b *ShelleyTransactionBody) Hash() string {
 
 func (b *ShelleyTransactionBody) Inputs() []common.TransactionInput {
 	ret := []common.TransactionInput{}
-	for _, input := range b.TxInputs {
+	for _, input := range b.TxInputs.Items() {
 		ret = append(ret, input)
 	}
 	return ret
@@ -357,6 +357,29 @@ func (b *ShelleyTransactionBody) Utxorpc() *utxorpc.Tx {
 	return tx
 }
 
+type ShelleyTransactionInputSet struct {
+	items []ShelleyTransactionInput
+}
+
+func (s *ShelleyTransactionInputSet) UnmarshalCBOR(data []byte) error {
+	// Make sure this isn't a tag-wrapped set
+	// This is needed to prevent Conway+ TXs from being decoded as an earlier type
+	var tmpTag cbor.RawTag
+	if _, err := cbor.Decode(data, &tmpTag); err == nil {
+		return fmt.Errorf("did not expect CBOR tag")
+	}
+	var tmpData []ShelleyTransactionInput
+	if _, err := cbor.Decode(data, &tmpData); err != nil {
+		return err
+	}
+	s.items = tmpData
+	return nil
+}
+
+func (s *ShelleyTransactionInputSet) Items() []ShelleyTransactionInput {
+	return s.items
+}
+
 type ShelleyTransactionInput struct {
 	cbor.StructAsArray
 	TxId        common.Blake2b256
@@ -386,8 +409,6 @@ func (i ShelleyTransactionInput) Utxorpc() *utxorpc.TxInput {
 	return &utxorpc.TxInput{
 		TxHash:      i.TxId.Bytes(),
 		OutputIndex: i.OutputIndex,
-		// AsOutput: i.AsOutput,
-		// Redeemer: i.Redeemer,
 	}
 }
 

ledger/tx_test.go

@@ -0,0 +1,47 @@
+// Copyright 2023 Blink Labs Software
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ledger_test
+
+import (
+	"encoding/hex"
+	"testing"
+
+	"github.com/blinklabs-io/gouroboros/ledger"
+)
+
+func TestDetermineTransactionType(t *testing.T) {
+	testDefs := []struct {
+		txCborHex      string
+		expectedTxType uint
+	}{
+		{
+			txCborHex:      "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",
+			expectedTxType: 6,
+		},
+	}
+	for _, testDef := range testDefs {
+		txCbor, err := hex.DecodeString(testDef.txCborHex)
+		if err != nil {
+			t.Fatalf("unexpected error: %s", err)
+		}
+		tmpTxType, err := ledger.DetermineTransactionType(txCbor)
+		if err != nil {
+			t.Fatalf("unexpected error: %s", err)
+		}
+		if tmpTxType != testDef.expectedTxType {
+			t.Fatalf("did not get expected TX type: got %d, wanted %d", tmpTxType, testDef.expectedTxType)
+		}
+	}
+}