[#140] sdk/object: Implement object format control functions

Implement function for calculating, setting and checking object verification
fields.

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>

pkg/object/fmt.go

@@ -0,0 +1,157 @@
+package object
+
+import (
+	"crypto/ecdsa"
+	"crypto/sha256"
+
+	"github.com/nspcc-dev/neofs-api-go/pkg"
+	"github.com/nspcc-dev/neofs-api-go/util/signature"
+	signatureV2 "github.com/nspcc-dev/neofs-api-go/v2/signature"
+	"github.com/pkg/errors"
+)
+
+// CalculatePayloadChecksum calculates and returns checksum of
+// object payload bytes.
+func CalculatePayloadChecksum(payload []byte) *pkg.Checksum {
+	res := pkg.NewChecksum()
+	res.SetSHA256(sha256.Sum256(payload))
+
+	return res
+}
+
+// CalculateAndSetPayloadChecksum calculates checksum of current
+// object payload and writes it to the object.
+func CalculateAndSetPayloadChecksum(obj *RawObject) {
+	obj.SetPayloadChecksum(
+		CalculatePayloadChecksum(obj.GetPayload()),
+	)
+}
+
+// VerifyPayloadChecksum checks if payload checksum in the object
+// corresponds to its payload.
+func VerifyPayloadChecksum(obj *Object) error {
+	if !pkg.EqualChecksums(
+		obj.GetPayloadChecksum(),
+		CalculatePayloadChecksum(obj.GetPayload()),
+	) {
+		return errors.New("payload checksum mismatch")
+	}
+
+	return nil
+}
+
+// CalculateID calculates identifier for the object.
+func CalculateID(obj *Object) (*ID, error) {
+	data, err := obj.ToV2().GetHeader().StableMarshal(nil)
+	if err != nil {
+		return nil, err
+	}
+
+	id := NewID()
+	id.SetSHA256(sha256.Sum256(data))
+
+	return id, nil
+}
+
+// CalculateAndSetID calculates identifier for the object
+// and writes the result to it.
+func CalculateAndSetID(obj *RawObject) error {
+	id, err := CalculateID(obj.Object())
+	if err != nil {
+		return err
+	}
+
+	obj.SetID(id)
+
+	return nil
+}
+
+// VerifyID checks if identifier in the object corresponds to
+// its structure.
+func VerifyID(obj *Object) error {
+	id, err := CalculateID(obj)
+	if err != nil {
+		return err
+	}
+
+	if !id.Equal(obj.GetID()) {
+		return errors.New("incorrect object identifier")
+	}
+
+	return nil
+}
+
+func CalculateIDSignature(key *ecdsa.PrivateKey, id *ID) (*pkg.Signature, error) {
+	sig := pkg.NewSignature()
+
+	if err := signature.SignDataWithHandler(
+		key,
+		signatureV2.StableMarshalerWrapper{
+			SM: id.ToV2(),
+		},
+		func(key, sign []byte) {
+			sig.SetKey(key)
+			sig.SetSign(sign)
+		},
+	); err != nil {
+		return nil, err
+	}
+
+	return sig, nil
+}
+
+func CalculateAndSetSignature(key *ecdsa.PrivateKey, obj *RawObject) error {
+	sig, err := CalculateIDSignature(key, obj.GetID())
+	if err != nil {
+		return err
+	}
+
+	obj.SetSignature(sig)
+
+	return nil
+}
+
+func VerifyIDSignature(obj *Object) error {
+	return signature.VerifyDataWithSource(
+		signatureV2.StableMarshalerWrapper{
+			SM: obj.GetID().ToV2(),
+		},
+		func() ([]byte, []byte) {
+			sig := obj.GetSignature()
+
+			return sig.GetKey(), sig.GetSign()
+		},
+	)
+}
+
+// SetVerificationFields calculates and sets all verification fields of the object.
+func SetVerificationFields(key *ecdsa.PrivateKey, obj *RawObject) error {
+	CalculateAndSetPayloadChecksum(obj)
+
+	if err := CalculateAndSetID(obj); err != nil {
+		return errors.Wrap(err, "could not set identifier")
+	}
+
+	if err := CalculateAndSetSignature(key, obj); err != nil {
+		return errors.Wrap(err, "could not set signature")
+	}
+
+	return nil
+}
+
+// CheckVerificationFields checks all verification fields of the object.
+func CheckVerificationFields(obj *Object) error {
+	if err := VerifyIDSignature(obj); err != nil {
+		return errors.Wrap(err, "invalid signature")
+	}
+
+	if err := VerifyID(obj); err != nil {
+		return errors.Wrap(err, "invalid identifier")
+	}
+
+	if err := VerifyPayloadChecksum(obj); err != nil {
+		return errors.Wrap(err, "invalid payload checksum")
+	}
+
+	return nil
+}

pkg/object/fmt_test.go

@@ -0,0 +1,79 @@
+package object
+
+import (
+	"crypto/rand"
+	"testing"
+
+	"github.com/nspcc-dev/neofs-crypto/test"
+	"github.com/stretchr/testify/require"
+)
+
+func TestVerificationFields(t *testing.T) {
+	obj := NewRaw()
+
+	payload := make([]byte, 10)
+	_, _ = rand.Read(payload)
+
+	obj.SetPayload(payload)
+	obj.SetPayloadSize(uint64(len(payload)))
+
+	require.NoError(t, SetVerificationFields(test.DecodeKey(-1), obj))
+
+	require.NoError(t, CheckVerificationFields(obj.Object()))
+
+	items := []struct {
+		corrupt func()
+		restore func()
+	}{
+		{
+			corrupt: func() {
+				payload[0]++
+			},
+			restore: func() {
+				payload[0]--
+			},
+		},
+		{
+			corrupt: func() {
+				obj.SetPayloadSize(obj.GetPayloadSize() + 1)
+			},
+			restore: func() {
+				obj.SetPayloadSize(obj.GetPayloadSize() - 1)
+			},
+		},
+		{
+			corrupt: func() {
+				obj.GetID().ToV2().GetValue()[0]++
+			},
+			restore: func() {
+				obj.GetID().ToV2().GetValue()[0]--
+			},
+		},
+		{
+			corrupt: func() {
+				obj.GetSignature().GetKey()[0]++
+			},
+			restore: func() {
+				obj.GetSignature().GetKey()[0]--
+			},
+		},
+		{
+			corrupt: func() {
+				obj.GetSignature().GetSign()[0]++
+			},
+			restore: func() {
+				obj.GetSignature().GetSign()[0]--
+			},
+		},
+	}
+
+	for _, item := range items {
+		item.corrupt()
+
+		require.Error(t, CheckVerificationFields(obj.Object()))
+
+		item.restore()
+
+		require.NoError(t, CheckVerificationFields(obj.Object()))
+	}
+}