[#6] services/util: Remove remaining stream wrappers

Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>

pkg/services/accounting/sign.go

@@ -23,5 +23,5 @@ func NewSignService(key *ecdsa.PrivateKey, svc Server) Server {
 
 func (s *signService) Balance(ctx context.Context, req *accounting.BalanceRequest) (*accounting.BalanceResponse, error) {
 	resp, err := util.EnsureNonNilResponse(s.svc.Balance(ctx, req))
-	return resp, s.sigSvc.SignResponse(req, resp, err)
+	return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 }

pkg/services/container/sign.go

@@ -24,62 +24,62 @@ func NewSignService(key *ecdsa.PrivateKey, svc Server) Server {
 func (s *signService) Put(ctx context.Context, req *container.PutRequest) (*container.PutResponse, error) {
 	if err := s.sigSvc.VerifyRequest(req); err != nil {
 		resp := new(container.PutResponse)
-		return resp, s.sigSvc.SignResponse(req, resp, err)
+		return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 	}
 	resp, err := util.EnsureNonNilResponse(s.svc.Put(ctx, req))
-	return resp, s.sigSvc.SignResponse(req, resp, err)
+	return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 }
 
 func (s *signService) Delete(ctx context.Context, req *container.DeleteRequest) (*container.DeleteResponse, error) {
 	if err := s.sigSvc.VerifyRequest(req); err != nil {
 		resp := new(container.DeleteResponse)
-		return resp, s.sigSvc.SignResponse(req, resp, err)
+		return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 	}
 	resp, err := util.EnsureNonNilResponse(s.svc.Delete(ctx, req))
-	return resp, s.sigSvc.SignResponse(req, resp, err)
+	return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 }
 
 func (s *signService) Get(ctx context.Context, req *container.GetRequest) (*container.GetResponse, error) {
 	if err := s.sigSvc.VerifyRequest(req); err != nil {
 		resp := new(container.GetResponse)
-		return resp, s.sigSvc.SignResponse(req, resp, err)
+		return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 	}
 	resp, err := util.EnsureNonNilResponse(s.svc.Get(ctx, req))
-	return resp, s.sigSvc.SignResponse(req, resp, err)
+	return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 }
 
 func (s *signService) List(ctx context.Context, req *container.ListRequest) (*container.ListResponse, error) {
 	if err := s.sigSvc.VerifyRequest(req); err != nil {
 		resp := new(container.ListResponse)
-		return resp, s.sigSvc.SignResponse(req, resp, err)
+		return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 	}
 	resp, err := util.EnsureNonNilResponse(s.svc.List(ctx, req))
-	return resp, s.sigSvc.SignResponse(req, resp, err)
+	return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 }
 
 func (s *signService) SetExtendedACL(ctx context.Context, req *container.SetExtendedACLRequest) (*container.SetExtendedACLResponse, error) {
 	if err := s.sigSvc.VerifyRequest(req); err != nil {
 		resp := new(container.SetExtendedACLResponse)
-		return resp, s.sigSvc.SignResponse(req, resp, err)
+		return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 	}
 	resp, err := util.EnsureNonNilResponse(s.svc.SetExtendedACL(ctx, req))
-	return resp, s.sigSvc.SignResponse(req, resp, err)
+	return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 }
 
 func (s *signService) GetExtendedACL(ctx context.Context, req *container.GetExtendedACLRequest) (*container.GetExtendedACLResponse, error) {
 	if err := s.sigSvc.VerifyRequest(req); err != nil {
 		resp := new(container.GetExtendedACLResponse)
-		return resp, s.sigSvc.SignResponse(req, resp, err)
+		return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 	}
 	resp, err := util.EnsureNonNilResponse(s.svc.GetExtendedACL(ctx, req))
-	return resp, s.sigSvc.SignResponse(req, resp, err)
+	return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 }
 
 func (s *signService) AnnounceUsedSpace(ctx context.Context, req *container.AnnounceUsedSpaceRequest) (*container.AnnounceUsedSpaceResponse, error) {
 	if err := s.sigSvc.VerifyRequest(req); err != nil {
 		resp := new(container.AnnounceUsedSpaceResponse)
-		return resp, s.sigSvc.SignResponse(req, resp, err)
+		return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 	}
 	resp, err := util.EnsureNonNilResponse(s.svc.AnnounceUsedSpace(ctx, req))
-	return resp, s.sigSvc.SignResponse(req, resp, err)
+	return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 }

pkg/services/netmap/sign.go

@@ -26,26 +26,26 @@ func (s *signService) LocalNodeInfo(
 	req *netmap.LocalNodeInfoRequest) (*netmap.LocalNodeInfoResponse, error) {
 	if err := s.sigSvc.VerifyRequest(req); err != nil {
 		resp := new(netmap.LocalNodeInfoResponse)
-		return resp, s.sigSvc.SignResponse(req, resp, err)
+		return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 	}
 	resp, err := util.EnsureNonNilResponse(s.svc.LocalNodeInfo(ctx, req))
-	return resp, s.sigSvc.SignResponse(req, resp, err)
+	return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 }
 
 func (s *signService) NetworkInfo(ctx context.Context, req *netmap.NetworkInfoRequest) (*netmap.NetworkInfoResponse, error) {
 	if err := s.sigSvc.VerifyRequest(req); err != nil {
 		resp := new(netmap.NetworkInfoResponse)
-		return resp, s.sigSvc.SignResponse(req, resp, err)
+		return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 	}
 	resp, err := util.EnsureNonNilResponse(s.svc.NetworkInfo(ctx, req))
-	return resp, s.sigSvc.SignResponse(req, resp, err)
+	return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 }
 
 func (s *signService) Snapshot(ctx context.Context, req *netmap.SnapshotRequest) (*netmap.SnapshotResponse, error) {
 	if err := s.sigSvc.VerifyRequest(req); err != nil {
 		resp := new(netmap.SnapshotResponse)
-		return resp, s.sigSvc.SignResponse(req, resp, err)
+		return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 	}
 	resp, err := util.EnsureNonNilResponse(s.svc.Snapshot(ctx, req))
-	return resp, s.sigSvc.SignResponse(req, resp, err)
+	return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 }

pkg/services/object/sign.go

@@ -18,27 +18,30 @@ type SignService struct {
 }
 
 type searchStreamSigner struct {
-	util.ServerStream
+	SearchStream
-
+	statusSupported bool
-	respWriter util.ResponseMessageWriter
+	sigSvc          *util.SignService
 
 	nonEmptyResp bool // set on first Send call
 }
 
 type getStreamSigner struct {
-	util.ServerStream
+	GetObjectStream
-
+	statusSupported bool
-	respWriter util.ResponseMessageWriter
+	sigSvc          *util.SignService
 }
 
 type putStreamSigner struct {
-	stream *util.RequestMessageStreamer
+	sigSvc          *util.SignService
+	stream          PutObjectStream
+	statusSupported bool
+	err             error
 }
 
 type getRangeStreamSigner struct {
-	util.ServerStream
+	GetObjectRangeStream
-
+	statusSupported bool
-	respWriter util.ResponseMessageWriter
+	sigSvc          *util.SignService
 }
 
 func NewSignService(key *ecdsa.PrivateKey, svc ServiceServer) *SignService {
@@ -50,37 +53,50 @@ func NewSignService(key *ecdsa.PrivateKey, svc ServiceServer) *SignService {
 }
 
 func (s *getStreamSigner) Send(resp *object.GetResponse) error {
-	return s.respWriter(resp)
+	if err := s.sigSvc.SignResponse(s.statusSupported, resp, nil); err != nil {
+		return err
+	}
+	return s.GetObjectStream.Send(resp)
 }
 
 func (s *SignService) Get(req *object.GetRequest, stream GetObjectStream) error {
-	return s.sigSvc.HandleServerStreamRequest(req,
+	if err := s.sigSvc.VerifyRequest(req); err != nil {
-		func(resp util.ResponseMessage) error {
+		resp := new(object.GetResponse)
-			return stream.Send(resp.(*object.GetResponse))
+		_ = s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
-		},
+		return stream.Send(resp)
-		func() util.ResponseMessage {
+	}
-			return new(object.GetResponse)
+
-		},
+	return s.svc.Get(req, &getStreamSigner{
-		func(respWriter util.ResponseMessageWriter) error {
+		GetObjectStream: stream,
-			return s.svc.Get(req, &getStreamSigner{
+		sigSvc:          s.sigSvc,
-				ServerStream: stream,
+		statusSupported: util.IsStatusSupported(req),
-				respWriter:   respWriter,
+	})
-			})
-		},
-	)
 }
 
 func (s *putStreamSigner) Send(ctx context.Context, req *object.PutRequest) error {
-	return s.stream.Send(ctx, req)
+	s.statusSupported = util.IsStatusSupported(req)
+
+	if s.err = s.sigSvc.VerifyRequest(req); s.err != nil {
+		return util.ErrAbortStream
+	}
+	if s.err = s.stream.Send(ctx, req); s.err != nil {
+		return util.ErrAbortStream
+	}
+	return nil
 }
 
-func (s *putStreamSigner) CloseAndRecv(ctx context.Context) (*object.PutResponse, error) {
+func (s *putStreamSigner) CloseAndRecv(ctx context.Context) (resp *object.PutResponse, err error) {
-	r, err := s.stream.CloseAndRecv(ctx)
+	if s.err != nil {
-	if err != nil {
+		err = s.err
-		return nil, fmt.Errorf("could not receive response: %w", err)
+		resp = new(object.PutResponse)
+	} else {
+		resp, err = s.stream.CloseAndRecv(ctx)
+		if err != nil {
+			return nil, fmt.Errorf("could not close stream and receive response: %w", err)
+		}
 	}
 
-	return r.(*object.PutResponse), nil
+	return resp, s.sigSvc.SignResponse(s.statusSupported, resp, err)
 }
 
 func (s *SignService) Put() (PutObjectStream, error) {
@@ -90,108 +106,96 @@ func (s *SignService) Put() (PutObjectStream, error) {
 	}
 
 	return &putStreamSigner{
-		stream: s.sigSvc.CreateRequestStreamer(
+		stream: stream,
-			func(ctx context.Context, req any) error {
+		sigSvc: s.sigSvc,
-				return stream.Send(ctx, req.(*object.PutRequest))
-			},
-			func(ctx context.Context) (util.ResponseMessage, error) {
-				return stream.CloseAndRecv(ctx)
-			},
-			func() util.ResponseMessage {
-				return new(object.PutResponse)
-			},
-		),
 	}, nil
 }
 
 func (s *SignService) Head(ctx context.Context, req *object.HeadRequest) (*object.HeadResponse, error) {
 	if err := s.sigSvc.VerifyRequest(req); err != nil {
 		resp := new(object.HeadResponse)
-		return resp, s.sigSvc.SignResponse(req, resp, err)
+		return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 	}
 	resp, err := util.EnsureNonNilResponse(s.svc.Head(ctx, req))
-	return resp, s.sigSvc.SignResponse(req, resp, err)
+	return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 }
 
 func (s *SignService) PutSingle(ctx context.Context, req *object.PutSingleRequest) (*object.PutSingleResponse, error) {
 	if err := s.sigSvc.VerifyRequest(req); err != nil {
 		resp := new(object.PutSingleResponse)
-		return resp, s.sigSvc.SignResponse(req, resp, err)
+		return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 	}
 	resp, err := util.EnsureNonNilResponse(s.svc.PutSingle(ctx, req))
-	return resp, s.sigSvc.SignResponse(req, resp, err)
+	return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 }
 
 func (s *searchStreamSigner) Send(resp *object.SearchResponse) error {
 	s.nonEmptyResp = true
-	return s.respWriter(resp)
+	if err := s.sigSvc.SignResponse(s.statusSupported, resp, nil); err != nil {
+		return err
+	}
+	return s.SearchStream.Send(resp)
 }
 
 func (s *SignService) Search(req *object.SearchRequest, stream SearchStream) error {
-	return s.sigSvc.HandleServerStreamRequest(req,
+	if err := s.sigSvc.VerifyRequest(req); err != nil {
-		func(resp util.ResponseMessage) error {
+		resp := new(object.SearchResponse)
-			return stream.Send(resp.(*object.SearchResponse))
+		_ = s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
-		},
+		return stream.Send(resp)
-		func() util.ResponseMessage {
+	}
-			return new(object.SearchResponse)
-		},
-		func(respWriter util.ResponseMessageWriter) error {
-			stream := &searchStreamSigner{
-				ServerStream: stream,
-				respWriter:   respWriter,
-			}
 
-			err := s.svc.Search(req, stream)
+	ss := &searchStreamSigner{
-
+		SearchStream:    stream,
-			if err == nil && !stream.nonEmptyResp {
+		sigSvc:          s.sigSvc,
-				// The higher component does not write any response in the case of an empty result (which is correct).
+		statusSupported: util.IsStatusSupported(req),
-				// With the introduction of status returns at least one answer must be signed and sent to the client.
+	}
-				// This approach is supported by clients who do not know how to work with statuses (one could make
+	err := s.svc.Search(req, ss)
-				// a switch according to the protocol version from the request, but the costs of sending an empty
+	if err == nil && !ss.nonEmptyResp {
-				// answer can be neglected due to the gradual refusal to use the "old" clients).
+		// The higher component does not write any response in the case of an empty result (which is correct).
-				return stream.Send(new(object.SearchResponse))
+		// With the introduction of status returns at least one answer must be signed and sent to the client.
-			}
+		// This approach is supported by clients who do not know how to work with statuses (one could make
-
+		// a switch according to the protocol version from the request, but the costs of sending an empty
-			return err
+		// answer can be neglected due to the gradual refusal to use the "old" clients).
-		},
+		return stream.Send(new(object.SearchResponse))
-	)
+	}
+	return err
 }
 
 func (s *SignService) Delete(ctx context.Context, req *object.DeleteRequest) (*object.DeleteResponse, error) {
 	if err := s.sigSvc.VerifyRequest(req); err != nil {
 		resp := new(object.DeleteResponse)
-		return resp, s.sigSvc.SignResponse(req, resp, err)
+		return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 	}
 	resp, err := util.EnsureNonNilResponse(s.svc.Delete(ctx, req))
-	return resp, s.sigSvc.SignResponse(req, resp, err)
+	return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 }
 
 func (s *getRangeStreamSigner) Send(resp *object.GetRangeResponse) error {
-	return s.respWriter(resp)
+	if err := s.sigSvc.SignResponse(s.statusSupported, resp, nil); err != nil {
+		return err
+	}
+	return s.GetObjectRangeStream.Send(resp)
 }
 
 func (s *SignService) GetRange(req *object.GetRangeRequest, stream GetObjectRangeStream) error {
-	return s.sigSvc.HandleServerStreamRequest(req,
+	if err := s.sigSvc.VerifyRequest(req); err != nil {
-		func(resp util.ResponseMessage) error {
+		resp := new(object.GetRangeResponse)
-			return stream.Send(resp.(*object.GetRangeResponse))
+		_ = s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
-		},
+		return stream.Send(resp)
-		func() util.ResponseMessage {
+	}
-			return new(object.GetRangeResponse)
+
-		},
+	return s.svc.GetRange(req, &getRangeStreamSigner{
-		func(respWriter util.ResponseMessageWriter) error {
+		GetObjectRangeStream: stream,
-			return s.svc.GetRange(req, &getRangeStreamSigner{
+		sigSvc:               s.sigSvc,
-				ServerStream: stream,
+		statusSupported:      util.IsStatusSupported(req),
-				respWriter:   respWriter,
+	})
-			})
-		},
-	)
 }
 
 func (s *SignService) GetRangeHash(ctx context.Context, req *object.GetRangeHashRequest) (*object.GetRangeHashResponse, error) {
 	if err := s.sigSvc.VerifyRequest(req); err != nil {
 		resp := new(object.GetRangeHashResponse)
-		return resp, s.sigSvc.SignResponse(req, resp, err)
+		return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 	}
 	resp, err := util.EnsureNonNilResponse(s.svc.GetRangeHash(ctx, req))
-	return resp, s.sigSvc.SignResponse(req, resp, err)
+	return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 }

pkg/services/session/sign.go

@@ -24,8 +24,8 @@ func NewSignService(key *ecdsa.PrivateKey, svc Server) Server {
 func (s *signService) Create(ctx context.Context, req *session.CreateRequest) (*session.CreateResponse, error) {
 	if err := s.sigSvc.VerifyRequest(req); err != nil {
 		resp := new(session.CreateResponse)
-		return resp, s.sigSvc.SignResponse(req, resp, err)
+		return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 	}
 	resp, err := util.EnsureNonNilResponse(s.svc.Create(ctx, req))
-	return resp, s.sigSvc.SignResponse(req, resp, err)
+	return resp, s.sigSvc.SignResponse(util.IsStatusSupported(req), resp, err)
 }

pkg/services/util/sign.go

@@ -1,7 +1,6 @@
 package util
 
 import (
-	"context"
 	"crypto/ecdsa"
 	"errors"
 	"fmt"
@@ -21,163 +20,23 @@ type ResponseMessage interface {
 	SetMetaHeader(*session.ResponseMetaHeader)
 }
 
-type UnaryHandler func(context.Context, any) (ResponseMessage, error)
-
 type SignService struct {
 	key *ecdsa.PrivateKey
 }
 
-type ResponseMessageWriter func(ResponseMessage) error
-
-type ServerStreamHandler func(context.Context, any) (ResponseMessageReader, error)
-
-type ResponseMessageReader func() (ResponseMessage, error)
-
 var ErrAbortStream = errors.New("abort message stream")
 
-type ResponseConstructor func() ResponseMessage
-
-type RequestMessageWriter func(context.Context, any) error
-
-type ClientStreamCloser func(context.Context) (ResponseMessage, error)
-
-type RequestMessageStreamer struct {
-	key *ecdsa.PrivateKey
-
-	send RequestMessageWriter
-
-	close ClientStreamCloser
-
-	respCons ResponseConstructor
-
-	statusSupported bool
-
-	sendErr error
-}
-
 func NewUnarySignService(key *ecdsa.PrivateKey) *SignService {
 	return &SignService{
 		key: key,
 	}
 }
 
-func (s *RequestMessageStreamer) Send(ctx context.Context, req any) error {
+// SignResponse response with private key via signature.SignServiceMessage.
-	// req argument should be strengthen with type RequestMessage
+// The signature error affects the result depending on the protocol version:
-	s.statusSupported = isStatusSupported(req.(RequestMessage)) // panic is OK here for now
+//   - if status return is supported, panics since we cannot return the failed status, because it will not be signed.
-
+//   - otherwise, returns error in order to transport it directly.
-	var err error
+func (s *SignService) SignResponse(statusSupported bool, resp ResponseMessage, err error) error {
-
-	// verify request signatures
-	if err = signature.VerifyServiceMessage(req); err != nil {
-		err = fmt.Errorf("could not verify request: %w", err)
-	} else {
-		err = s.send(ctx, req)
-	}
-
-	if err != nil {
-		if !s.statusSupported {
-			return err
-		}
-
-		s.sendErr = err
-
-		return ErrAbortStream
-	}
-
-	return nil
-}
-
-func (s *RequestMessageStreamer) CloseAndRecv(ctx context.Context) (ResponseMessage, error) {
-	var (
-		resp ResponseMessage
-		err  error
-	)
-
-	if s.sendErr != nil {
-		err = s.sendErr
-	} else {
-		resp, err = s.close(ctx)
-		if err != nil {
-			err = fmt.Errorf("could not close stream and receive response: %w", err)
-		}
-	}
-
-	if err != nil {
-		if !s.statusSupported {
-			return nil, err
-		}
-
-		resp = s.respCons()
-
-		setStatusV2(resp, err)
-	}
-
-	if err = signResponse(s.key, resp, s.statusSupported); err != nil {
-		return nil, err
-	}
-
-	return resp, nil
-}
-
-func (s *SignService) CreateRequestStreamer(sender RequestMessageWriter, closer ClientStreamCloser, blankResp ResponseConstructor) *RequestMessageStreamer {
-	return &RequestMessageStreamer{
-		key:   s.key,
-		send:  sender,
-		close: closer,
-
-		respCons: blankResp,
-	}
-}
-
-func (s *SignService) HandleServerStreamRequest(
-	req any,
-	respWriter ResponseMessageWriter,
-	blankResp ResponseConstructor,
-	respWriterCaller func(ResponseMessageWriter) error,
-) error {
-	// handle protocol versions <=2.10 (API statuses was introduced in 2.11 only)
-
-	// req argument should be strengthen with type RequestMessage
-	statusSupported := isStatusSupported(req.(RequestMessage)) // panic is OK here for now
-
-	var err error
-
-	// verify request signatures
-	if err = signature.VerifyServiceMessage(req); err != nil {
-		err = fmt.Errorf("could not verify request: %w", err)
-	} else {
-		err = respWriterCaller(func(resp ResponseMessage) error {
-			if err := signResponse(s.key, resp, statusSupported); err != nil {
-				return err
-			}
-
-			return respWriter(resp)
-		})
-	}
-
-	if err != nil {
-		if !statusSupported {
-			return err
-		}
-
-		resp := blankResp()
-
-		setStatusV2(resp, err)
-
-		_ = signResponse(s.key, resp, false) // panics or returns nil with false arg
-
-		return respWriter(resp)
-	}
-
-	return nil
-}
-
-func (s *SignService) SignResponse(req RequestMessage, resp ResponseMessage, err error) error {
-	// handle protocol versions <=2.10 (API statuses was introduced in 2.11 only)
-
-	// req argument should be strengthen with type RequestMessage
-	statusSupported := isStatusSupported(req)
-
 	if err != nil {
 		if !statusSupported {
 			return err
@@ -186,8 +45,18 @@ func (s *SignService) SignResponse(req RequestMessage, resp ResponseMessage, err
 		setStatusV2(resp, err)
 	}
 
-	// sign the response
+	err = signature.SignServiceMessage(s.key, resp)
-	return signResponse(s.key, resp, statusSupported)
+	if err != nil {
+		err = fmt.Errorf("could not sign response: %w", err)
+
+		if statusSupported {
+			// We can't pass this error as status code since response will be unsigned.
+			// Isn't expected in practice, so panic is ok here.
+			panic(err)
+		}
+	}
+
+	return err
 }
 
 func (s *SignService) VerifyRequest(req RequestMessage) error {
@@ -207,7 +76,9 @@ func EnsureNonNilResponse[T any](resp *T, err error) (*T, error) {
 	return new(T), err
 }
 
-func isStatusSupported(req RequestMessage) bool {
+// IsStatusSupported returns true iff request version implies expecting status return.
+// This allows us to handle protocol versions <=2.10 (API statuses was introduced in 2.11 only).
+func IsStatusSupported(req RequestMessage) bool {
 	version := req.GetMetaHeader().GetVersion()
 
 	mjr := version.GetMajor()
@@ -223,22 +94,3 @@ func setStatusV2(resp ResponseMessage, err error) {
 
 	session.SetStatus(resp, apistatus.ToStatusV2(apistatus.ErrToStatus(err)))
 }
-
-// signs response with private key via signature.SignServiceMessage.
-// The signature error affects the result depending on the protocol version:
-//   - if status return is supported, panics since we cannot return the failed status, because it will not be signed;
-//   - otherwise, returns error in order to transport it directly.
-func signResponse(key *ecdsa.PrivateKey, resp any, statusSupported bool) error {
-	err := signature.SignServiceMessage(key, resp)
-	if err != nil {
-		err = fmt.Errorf("could not sign response: %w", err)
-
-		if statusSupported {
-			// We can't pass this error as status code since response will be unsigned.
-			// Isn't expected in practice, so panic is ok here.
-			panic(err)
-		}
-	}
-
-	return err
-}