RPC omit errors when empty (#124)

* Omit errors in JSON RPC if empty and omit response in case of an error

* Address deprecation warning for the linter config

.golangci.yml

@@ -1,13 +1,7 @@
 ---
 run:
   timeout: 5m
-  skip-dirs:
-    - state/runtime/fakevm
-    - state/runtime/instrumentation
-    - test
-    - ci
-    - mocks
-
+
 linters:
   enable:
   - whitespace # Tool for detection of leading and trailing whitespace
@@ -50,6 +44,12 @@ issues:
         linters:
           - gosec
           - lll
+  exclude-dirs:
+    - state/runtime/fakevm
+    - state/runtime/instrumentation
+    - test
+    - ci
+    - mocks
   include:
   - EXC0012  # EXC0012 revive: Annoying issue about not having a comment. The rare codebase has such comments
   - EXC0014  # EXC0014 revive: Annoying issue about not having a comment. The rare codebase has such comments

rpc/handler.go

@@ -197,7 +197,7 @@ func (h *Handler) registerService(service Service) {
 			fv: mv.Func,
 		}
 		var err error
-		if fd.inNum, fd.reqt, err = validateFunc(funcName, fd.fv, true); err != nil {
+		if fd.inNum, fd.reqt, err = validateFunc(funcName, fd.fv); err != nil {
 			panic(fmt.Sprintf("jsonrpc: %s", err))
 		}
 		// check if last item is a pointer
@@ -217,10 +217,11 @@ func (h *Handler) registerService(service Service) {
 }
 
 func (h *Handler) getFnHandler(req Request) (*serviceData, *funcData, Error) {
+	const endpointNameParts = 2
 	methodNotFoundErrorMessage := fmt.Sprintf("the method %s does not exist/is not available", req.Method)
 
-	callName := strings.SplitN(req.Method, "_", 2) //nolint:mnd
-	if len(callName) != 2 {                        //nolint:mnd
+	callName := strings.SplitN(req.Method, "_", endpointNameParts)
+	if len(callName) != endpointNameParts {
 		return nil, nil, NewRPCError(NotFoundErrorCode, methodNotFoundErrorMessage)
 	}
 
@@ -238,9 +239,9 @@ func (h *Handler) getFnHandler(req Request) (*serviceData, *funcData, Error) {
 	return service, fd, nil
 }
 
-func validateFunc(funcName string, fv reflect.Value, isMethod bool) (inNum int, reqt []reflect.Type, err error) {
+func validateFunc(funcName string, fv reflect.Value) (inNum int, reqt []reflect.Type, err error) {
 	if funcName == "" {
-		err = fmt.Errorf("getBlockNumByArg cannot be empty")
+		err = fmt.Errorf("function name cannot be empty")
 		return
 	}
 

rpc/types.go

@@ -18,8 +18,8 @@ type Request struct {
 type Response struct {
 	JSONRPC string          `json:"jsonrpc"`
 	ID      interface{}     `json:"id"`
-	Result  json.RawMessage `json:"result"`
-	Error   *ErrorObject    `json:"error"`
+	Result  json.RawMessage `json:"result,omitempty"`
+	Error   *ErrorObject    `json:"error,omitempty"`
 }
 
 // NewResponse returns Success/Error response object

services/datacom/datacom.go

@@ -51,23 +51,23 @@ func (d *Endpoints) signSequence(signedSequence types.SignedSequenceInterface) (
 	// Verify that the request comes from the sequencer
 	sender, err := signedSequence.Signer()
 	if err != nil {
-		return "0x0", rpc.NewRPCError(rpc.DefaultErrorCode, "failed to verify sender")
+		return nil, rpc.NewRPCError(rpc.DefaultErrorCode, "failed to verify sender")
 	}
 
 	if sender != d.sequencerTracker.GetAddr() {
-		return "0x0", rpc.NewRPCError(rpc.DefaultErrorCode, "unauthorized")
+		return nil, rpc.NewRPCError(rpc.DefaultErrorCode, "unauthorized")
 	}
 
 	// Store off-chain data by hash (hash(L2Data): L2Data)
 	if err = d.db.StoreOffChainData(context.Background(), signedSequence.OffChainData()); err != nil {
-		return "0x0", rpc.NewRPCError(rpc.DefaultErrorCode,
+		return nil, rpc.NewRPCError(rpc.DefaultErrorCode,
 			fmt.Errorf("failed to store offchain data. Error: %w", err).Error())
 	}
 
 	// Sign
 	signature, err := signedSequence.Sign(d.privateKey)
 	if err != nil {
-		return "0x0", rpc.NewRPCError(rpc.DefaultErrorCode, fmt.Errorf("failed to sign. Error: %w", err).Error())
+		return nil, rpc.NewRPCError(rpc.DefaultErrorCode, fmt.Errorf("failed to sign. Error: %w", err).Error())
 	}
 	// Return signature
 	return signature, nil

services/status/status.go

@@ -37,11 +37,15 @@ func (s *Endpoints) GetStatus() (interface{}, rpc.Error) {
 	rowCount, err := s.db.CountOffchainData(ctx)
 	if err != nil {
 		log.Errorf("failed to get the key count from the offchain_data table: %v", err)
+
+		return nil, rpc.NewRPCError(rpc.DefaultErrorCode, "failed to retrieve data from the storage")
 	}
 
 	lastSynchronizedBlock, err := s.db.GetLastProcessedBlock(ctx, string(synchronizer.L1SyncTask))
 	if err != nil {
 		log.Errorf("failed to get last block processed by the synchronizer: %v", err)
+
+		return nil, rpc.NewRPCError(rpc.DefaultErrorCode, "failed to retrieve data from the storage")
 	}
 
 	return types.DACStatus{

services/status/status_test.go

@@ -30,11 +30,13 @@ func TestEndpoints_GetStatus(t *testing.T) {
 			name:                  "failed to count offchain data",
 			countOffchainDataErr:  errors.New("test error"),
 			getLastProcessedBlock: 2,
+			expectedError:         errors.New("failed to retrieve data from the storage"),
 		},
 		{
 			name:                     "failed to count offchain data and last processed block",
 			countOffchainDataErr:     errors.New("test error"),
 			getLastProcessedBlockErr: errors.New("test error"),
+			expectedError:            errors.New("failed to retrieve data from the storage"),
 		},
 	}
 
@@ -50,7 +52,7 @@ func TestEndpoints_GetStatus(t *testing.T) {
 				Return(tt.countOffchainData, tt.countOffchainDataErr)
 
 			dbMock.On("GetLastProcessedBlock", mock.Anything, mock.Anything).
-				Return(tt.getLastProcessedBlock, tt.getLastProcessedBlockErr)
+				Return(tt.getLastProcessedBlock, tt.getLastProcessedBlockErr).Maybe()
 
 			statusEndpoints := NewEndpoints(dbMock)
 

services/sync/sync.go

@@ -35,7 +35,7 @@ func (z *Endpoints) GetOffChainData(hash types.ArgHash) (interface{}, rpc.Error)
 	data, err := z.db.GetOffChainData(context.Background(), hash.Hash())
 	if err != nil {
 		log.Errorf("failed to get the offchain requested data from the DB: %v", err)
-		return "0x0", rpc.NewRPCError(rpc.DefaultErrorCode, "failed to get the requested data")
+		return nil, rpc.NewRPCError(rpc.DefaultErrorCode, "failed to get the requested data")
 	}
 
 	return types.ArgBytes(data.Value), nil
@@ -45,7 +45,7 @@ func (z *Endpoints) GetOffChainData(hash types.ArgHash) (interface{}, rpc.Error)
 func (z *Endpoints) ListOffChainData(hashes []types.ArgHash) (interface{}, rpc.Error) {
 	if len(hashes) > maxListHashes {
 		log.Errorf("too many hashes requested in ListOffChainData: %d", len(hashes))
-		return "0x0", rpc.NewRPCError(rpc.InvalidRequestErrorCode, "too many hashes requested")
+		return nil, rpc.NewRPCError(rpc.InvalidRequestErrorCode, "too many hashes requested")
 	}
 
 	keys := make([]common.Hash, len(hashes))
@@ -56,10 +56,10 @@ func (z *Endpoints) ListOffChainData(hashes []types.ArgHash) (interface{}, rpc.E
 	list, err := z.db.ListOffChainData(context.Background(), keys)
 	if err != nil {
 		log.Errorf("failed to list the requested data from the DB: %v", err)
-		return "0x0", rpc.NewRPCError(rpc.DefaultErrorCode, "failed to list the requested data")
+		return nil, rpc.NewRPCError(rpc.DefaultErrorCode, "failed to list the requested data")
 	}
 
-	listMap := make(map[common.Hash]types.ArgBytes)
+	listMap := make(map[common.Hash]types.ArgBytes, len(list))
 	for _, data := range list {
 		listMap[data.Key] = data.Value
 	}