transaction: implement OracleResponse attribute

pkg/core/transaction/attribute.go

@@ -10,7 +10,15 @@ import (
 
 // Attribute represents a Transaction attribute.
 type Attribute struct {
-	Type AttrType
+	Type  AttrType
+	Value interface {
+		io.Serializable
+		// toJSONMap is used for embedded json struct marshalling.
+		// Anonymous interface fields are not considered anonymous by
+		// json lib and marshaling Value together with type makes code
+		// harder to follow.
+		toJSONMap(map[string]interface{})
+	}
 }
 
 // attrJSON is used for JSON I/O of Attribute.
@@ -24,6 +32,9 @@ func (attr *Attribute) DecodeBinary(br *io.BinReader) {
 
 	switch attr.Type {
 	case HighPriority:
+	case OracleResponseT:
+		attr.Value = new(OracleResponse)
+		attr.Value.DecodeBinary(br)
 	default:
 		br.Err = fmt.Errorf("failed decoding TX attribute usage: 0x%2x", int(attr.Type))
 		return
@@ -35,6 +46,8 @@ func (attr *Attribute) EncodeBinary(bw *io.BinWriter) {
 	bw.WriteB(byte(attr.Type))
 	switch attr.Type {
 	case HighPriority:
+	case OracleResponseT:
+		attr.Value.EncodeBinary(bw)
 	default:
 		bw.Err = fmt.Errorf("failed encoding TX attribute usage: 0x%2x", attr.Type)
 	}
@@ -42,9 +55,11 @@ func (attr *Attribute) EncodeBinary(bw *io.BinWriter) {
 
 // MarshalJSON implements the json Marshaller interface.
 func (attr *Attribute) MarshalJSON() ([]byte, error) {
-	return json.Marshal(attrJSON{
-		Type: attr.Type.String(),
-	})
+	m := map[string]interface{}{"type": attr.Type.String()}
+	if attr.Value != nil {
+		attr.Value.toJSONMap(m)
+	}
+	return json.Marshal(m)
 }
 
 // UnmarshalJSON implements the json.Unmarshaller interface.
@@ -57,6 +72,12 @@ func (attr *Attribute) UnmarshalJSON(data []byte) error {
 	switch aj.Type {
 	case "HighPriority":
 		attr.Type = HighPriority
+	case "OracleResponse":
+		attr.Type = OracleResponseT
+		// Note: because `type` field will not be present in any attribute
+		// value, we can unmarshal the same data. The overhead is minimal.
+		attr.Value = new(OracleResponse)
+		return json.Unmarshal(data, attr.Value)
 	default:
 		return errors.New("wrong Type")
 

pkg/core/transaction/attribute_test.go

@@ -0,0 +1,66 @@
+package transaction
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"testing"
+
+	"github.com/nspcc-dev/neo-go/pkg/internal/testserdes"
+	"github.com/stretchr/testify/require"
+)
+
+func TestAttribute_EncodeBinary(t *testing.T) {
+	t.Run("HighPriority", func(t *testing.T) {
+		attr := &Attribute{
+			Type: HighPriority,
+		}
+		testserdes.EncodeDecodeBinary(t, attr, new(Attribute))
+	})
+	t.Run("OracleResponse", func(t *testing.T) {
+		attr := &Attribute{
+			Type: OracleResponseT,
+			Value: &OracleResponse{
+				ID:     0x1122334455,
+				Code:   Success,
+				Result: []byte{1, 2, 3},
+			},
+		}
+		testserdes.EncodeDecodeBinary(t, attr, new(Attribute))
+	})
+}
+
+func TestAttribute_MarshalJSON(t *testing.T) {
+	t.Run("HighPriority", func(t *testing.T) {
+		attr := &Attribute{Type: HighPriority}
+		data, err := json.Marshal(attr)
+		require.NoError(t, err)
+		require.JSONEq(t, `{"type":"HighPriority"}`, string(data))
+
+		actual := new(Attribute)
+		require.NoError(t, json.Unmarshal(data, actual))
+		require.Equal(t, attr, actual)
+	})
+	t.Run("OracleResponse", func(t *testing.T) {
+		res := []byte{1, 2, 3}
+		attr := &Attribute{
+			Type: OracleResponseT,
+			Value: &OracleResponse{
+				ID:     123,
+				Code:   Success,
+				Result: res,
+			},
+		}
+		data, err := json.Marshal(attr)
+		require.NoError(t, err)
+		require.JSONEq(t, `{
+			"type":"OracleResponse",
+			"id": 123,
+			"code": 0,
+			"result": "`+base64.StdEncoding.EncodeToString(res)+`"}`, string(data))
+
+		actual := new(Attribute)
+		require.NoError(t, json.Unmarshal(data, actual))
+		require.Equal(t, attr, actual)
+		testserdes.EncodeDecodeBinary(t, attr, new(Attribute))
+	})
+}

pkg/core/transaction/attrtype.go

@@ -1,11 +1,16 @@
 package transaction
 
-//go:generate stringer -type=AttrType
+//go:generate stringer -type=AttrType -linecomment
 
 // AttrType represents the purpose of the attribute.
 type AttrType uint8
 
 // List of valid attribute types.
 const (
-	HighPriority AttrType = 1
+	HighPriority    AttrType = 1
+	OracleResponseT AttrType = 0x11 // OracleResponse
 )
+
+func (a AttrType) allowMultiple() bool {
+	return false
+}

pkg/core/transaction/attrtype_string.go

@@ -1,4 +1,4 @@
-// Code generated by "stringer -type AttrType"; DO NOT EDIT.
+// Code generated by "stringer -type=AttrType -linecomment"; DO NOT EDIT.
 
 package transaction
 
@@ -9,16 +9,21 @@ func _() {
 	// Re-run the stringer command to generate them again.
 	var x [1]struct{}
 	_ = x[HighPriority-1]
+	_ = x[OracleResponseT-17]
 }
 
-const _AttrType_name = "HighPriority"
-
-var _AttrType_index = [...]uint8{0, 12}
+const (
+	_AttrType_name_0 = "HighPriority"
+	_AttrType_name_1 = "OracleResponse"
+)
 
 func (i AttrType) String() string {
-	i -= 1
-	if i >= AttrType(len(_AttrType_index)-1) {
-		return "AttrType(" + strconv.FormatInt(int64(i+1), 10) + ")"
+	switch {
+	case i == 1:
+		return _AttrType_name_0
+	case i == 17:
+		return _AttrType_name_1
+	default:
+		return "AttrType(" + strconv.FormatInt(int64(i), 10) + ")"
 	}
-	return _AttrType_name[_AttrType_index[i]:_AttrType_index[i+1]]
 }

pkg/core/transaction/oracle.go

@@ -0,0 +1,66 @@
+package transaction
+
+import (
+	"errors"
+
+	"github.com/nspcc-dev/neo-go/pkg/io"
+)
+
+// OracleResponseCode represents result code of oracle response.
+type OracleResponseCode byte
+
+// OracleResponse represents oracle response.
+type OracleResponse struct {
+	ID     uint64             `json:"id"`
+	Code   OracleResponseCode `json:"code"`
+	Result []byte             `json:"result"`
+}
+
+const maxResultSize = 1024
+
+// Enumeration of possible oracle response types.
+const (
+	Success   OracleResponseCode = 0x00
+	NotFound  OracleResponseCode = 0x10
+	Timeout   OracleResponseCode = 0x12
+	Forbidden OracleResponseCode = 0x14
+	Error     OracleResponseCode = 0xff
+)
+
+// Various validation errors.
+var (
+	ErrInvalidResponseCode = errors.New("invalid oracle response code")
+	ErrInvalidResult       = errors.New("oracle response != success, but result is not empty")
+)
+
+// IsValid checks if c is valid response code.
+func (c OracleResponseCode) IsValid() bool {
+	return c == Success || c == NotFound || c == Timeout || c == Forbidden || c == Error
+}
+
+// DecodeBinary implements io.Serializable interface.
+func (r *OracleResponse) DecodeBinary(br *io.BinReader) {
+	r.ID = br.ReadU64LE()
+	r.Code = OracleResponseCode(br.ReadB())
+	if !r.Code.IsValid() {
+		br.Err = ErrInvalidResponseCode
+		return
+	}
+	r.Result = br.ReadVarBytes(maxResultSize)
+	if r.Code != Success && len(r.Result) > 0 {
+		br.Err = ErrInvalidResult
+	}
+}
+
+// EncodeBinary implements io.Serializable interface.
+func (r *OracleResponse) EncodeBinary(w *io.BinWriter) {
+	w.WriteU64LE(r.ID)
+	w.WriteB(byte(r.Code))
+	w.WriteVarBytes(r.Result)
+}
+
+func (r *OracleResponse) toJSONMap(m map[string]interface{}) {
+	m["id"] = r.ID
+	m["code"] = r.Code
+	m["result"] = r.Result
+}

pkg/core/transaction/oracle_test.go

@@ -0,0 +1,76 @@
+package transaction
+
+import (
+	"encoding/json"
+	"errors"
+	"math/rand"
+	"testing"
+
+	"github.com/nspcc-dev/neo-go/pkg/internal/testserdes"
+	"github.com/stretchr/testify/require"
+)
+
+func TestOracleResponse_EncodeBinary(t *testing.T) {
+	t.Run("Success", func(t *testing.T) {
+		r := &OracleResponse{
+			ID:     rand.Uint64(),
+			Code:   Success,
+			Result: []byte{1, 2, 3, 4, 5},
+		}
+		testserdes.EncodeDecodeBinary(t, r, new(OracleResponse))
+	})
+	t.Run("ErrorCodes", func(t *testing.T) {
+		codes := []OracleResponseCode{NotFound, Timeout, Forbidden, Error}
+		for _, c := range codes {
+			r := &OracleResponse{
+				ID:     rand.Uint64(),
+				Code:   c,
+				Result: []byte{},
+			}
+			testserdes.EncodeDecodeBinary(t, r, new(OracleResponse))
+		}
+	})
+	t.Run("Error", func(t *testing.T) {
+		t.Run("InvalidCode", func(t *testing.T) {
+			r := &OracleResponse{
+				ID:     rand.Uint64(),
+				Code:   0x42,
+				Result: []byte{},
+			}
+			bs, err := testserdes.EncodeBinary(r)
+			require.NoError(t, err)
+
+			err = testserdes.DecodeBinary(bs, new(OracleResponse))
+			require.True(t, errors.Is(err, ErrInvalidResponseCode), "got: %v", err)
+		})
+		t.Run("InvalidResult", func(t *testing.T) {
+			r := &OracleResponse{
+				ID:     rand.Uint64(),
+				Code:   Error,
+				Result: []byte{1},
+			}
+			bs, err := testserdes.EncodeBinary(r)
+			require.NoError(t, err)
+
+			err = testserdes.DecodeBinary(bs, new(OracleResponse))
+			require.True(t, errors.Is(err, ErrInvalidResult), "got: %v", err)
+		})
+	})
+}
+
+func TestOracleResponse_toJSONMap(t *testing.T) {
+	r := &OracleResponse{
+		ID:     rand.Uint64(),
+		Code:   Success,
+		Result: []byte{1},
+	}
+
+	b1, err := json.Marshal(r)
+	require.NoError(t, err)
+
+	m := map[string]interface{}{}
+	r.toJSONMap(m)
+	b2, err := json.Marshal(m)
+	require.NoError(t, err)
+	require.JSONEq(t, string(b1), string(b2))
+}

pkg/core/transaction/transaction.go

@@ -381,14 +381,14 @@ func (t *Transaction) isValid() error {
 			}
 		}
 	}
-	hasHighPrio := false
+	attrs := map[AttrType]bool{}
 	for i := range t.Attributes {
-		switch t.Attributes[i].Type {
-		case HighPriority:
-			if hasHighPrio {
-				return fmt.Errorf("%w: multiple high priority attributes", ErrInvalidAttribute)
+		typ := t.Attributes[i].Type
+		if !typ.allowMultiple() {
+			if attrs[typ] {
+				return fmt.Errorf("%w: multiple '%s' attributes", ErrInvalidAttribute, typ.String())
 			}
-			hasHighPrio = true
+			attrs[typ] = true
 		}
 	}
 	if len(t.Script) == 0 {

pkg/core/transaction/transaction_test.go

@@ -206,6 +206,14 @@ func TestTransaction_isValid(t *testing.T) {
 		}
 		require.True(t, errors.Is(tx.isValid(), ErrInvalidAttribute))
 	})
+	t.Run("MultipleOracle", func(t *testing.T) {
+		tx := newTx()
+		tx.Attributes = []Attribute{
+			{Type: OracleResponseT},
+			{Type: OracleResponseT},
+		}
+		require.True(t, errors.Is(tx.isValid(), ErrInvalidAttribute))
+	})
 	t.Run("NoScript", func(t *testing.T) {
 		tx := newTx()
 		tx.Script = []byte{}