session: implement SignedDataSource on CreateRequest

session/request.go

@@ -1,5 +1,19 @@
 package session
 
+import (
+	"encoding/binary"
+	"io"
+
+	"github.com/nspcc-dev/neofs-api-go/refs"
+)
+
+const signedRequestDataSize = 0 +
+	refs.OwnerIDSize +
+	8 +
+	8
+
+var requestEndianness = binary.BigEndian
+
 // GetOwnerID is an OwnerID field getter.
 func (m CreateRequest) GetOwnerID() OwnerID {
 	return m.OwnerID
@@ -9,3 +23,36 @@ func (m CreateRequest) GetOwnerID() OwnerID {
 func (m *CreateRequest) SetOwnerID(id OwnerID) {
 	m.OwnerID = id
 }
+
+func (m CreateRequest) SignedData() ([]byte, error) {
+	data := make([]byte, m.SignedDataSize())
+
+	_, err := m.ReadSignedData(data)
+	if err != nil {
+		return nil, err
+	}
+
+	return data, nil
+}
+
+func (m CreateRequest) SignedDataSize() int {
+	return signedRequestDataSize
+}
+
+func (m CreateRequest) ReadSignedData(p []byte) (int, error) {
+	sz := m.SignedDataSize()
+	if len(p) < sz {
+		return 0, io.ErrUnexpectedEOF
+	}
+
+	var off int
+
+	off += copy(p[off:], m.GetOwnerID().Bytes())
+
+	requestEndianness.PutUint64(p[off:], m.CreationEpoch())
+	off += 8
+
+	requestEndianness.PutUint64(p[off:], m.ExpirationEpoch())
+
+	return sz, nil
+}

session/request_test.go

@@ -27,3 +27,66 @@ func TestCreateRequestGettersSetters(t *testing.T) {
 		require.Equal(t, e2, m.ExpirationEpoch())
 	})
 }
+
+func TestCreateRequest_SignedData(t *testing.T) {
+	var (
+		id = OwnerID{1, 2, 3}
+		e1 = uint64(1)
+		e2 = uint64(2)
+	)
+
+	// create new message
+	m := new(CreateRequest)
+
+	// fill the fields
+	m.SetOwnerID(id)
+	m.SetCreationEpoch(e1)
+	m.SetExpirationEpoch(e2)
+
+	// calculate initial signed data
+	d, err := m.SignedData()
+	require.NoError(t, err)
+
+	items := []struct {
+		change func()
+		reset  func()
+	}{
+		{ // OwnerID
+			change: func() {
+				id2 := id
+				id2[0]++
+				m.SetOwnerID(id2)
+			},
+			reset: func() {
+				m.SetOwnerID(id)
+			},
+		},
+		{ // CreationEpoch
+			change: func() {
+				m.SetCreationEpoch(e1 + 1)
+			},
+			reset: func() {
+				m.SetCreationEpoch(e1)
+			},
+		},
+		{ // ExpirationEpoch
+			change: func() {
+				m.SetExpirationEpoch(e2 + 1)
+			},
+			reset: func() {
+				m.SetExpirationEpoch(e2)
+			},
+		},
+	}
+
+	for _, item := range items {
+		item.change()
+
+		d2, err := m.SignedData()
+		require.NoError(t, err)
+
+		require.NotEqual(t, d, d2)
+
+		item.reset()
+	}
+}