throw error on over limit get blocks (#684)

* throw error on over limit get blocks

* move limit validation to handler layer

Author: nawikart

api/handler/blockHandler.go

@@ -2,10 +2,14 @@ package handler
 
 import (
 	"context"
+	"fmt"
 
 	"github.com/zoobc/zoobc-core/api/service"
+	"github.com/zoobc/zoobc-core/common/constant"
 	"github.com/zoobc/zoobc-core/common/chaintype"
 	"github.com/zoobc/zoobc-core/common/model"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
 )
 
 // BlockHandler to handle request related to Blocks from client
@@ -35,6 +39,10 @@ func (bs *BlockHandler) GetBlock(ctx context.Context, req *model.GetBlockRequest
 
 // GetBlocks handles request to get data of multiple blocks
 func (bs *BlockHandler) GetBlocks(ctx context.Context, req *model.GetBlocksRequest) (*model.GetBlocksResponse, error) {
+	if req.Limit > constant.MaxAPIGetBlocks {
+		return nil, status.Error(codes.OutOfRange, fmt.Sprintf("limit exceeded, max. %d", constant.MaxAPIGetBlocks))
+	}
+
 	chainType := chaintype.GetChainType(req.ChainType)
 	blocksResponse, err := bs.Service.GetBlocks(chainType, req.Limit, req.Height)
 	if err != nil {

common/constant/api.go

@@ -2,4 +2,5 @@ package constant
 
 var (
 	MaxAPIRequestPerSecond uint32 = 10
+	MaxAPIGetBlocks        uint32 = 500
 )