Add transaction rate-limit functionality

api/utils.go

@@ -132,6 +132,8 @@ func handleError[T any](err error, log zerolog.Logger, collector metrics.Collect
 		return zero, err
 	case errors.Is(err, core.ErrInsufficientFunds):
 		return zero, err
+	case errors.Is(err, errs.ErrRateLimit):
+		return zero, err
 	default:
 		collector.ApiErrorOccurred()
 		log.Error().Err(err).Msg("api error")

cmd/run/cmd.go

@@ -280,4 +280,6 @@ func init() {
 	Cmd.Flags().StringVar(&cfg.ProfilerHost, "profiler-host", "localhost", "Host for the Profiler server")
 	Cmd.Flags().IntVar(&cfg.ProfilerPort, "profiler-port", 6060, "Port for the Profiler server")
 	Cmd.Flags().StringVar(&txStateValidation, "tx-state-validation", "tx-seal", "Sets the transaction validation mechanism. It can validate using the local state index, or wait for the outer Flow transaction to seal. Available values ('local-index' / 'tx-seal'), defaults to 'tx-seal'.")
+	Cmd.Flags().Uint64Var(&cfg.TxRequestLimit, "tx-request-limit", 0, "Number of transaction submissions to allow per the specified interval.")
+	Cmd.Flags().DurationVar(&cfg.TxRequestLimitDuration, "tx-request-limit-duration", time.Second*3, "Time interval upon which to enforce transaction submission rate limiting.")
 }

config/config.go

@@ -89,4 +89,9 @@ type Config struct {
 	// TxStateValidation sets the transaction validation mechanism. It can validate
 	// using the local state index, or wait for the outer Flow transaction to seal.
 	TxStateValidation string
+	// TxRequestLimit is the number of transaction submissions to allow per interval.
+	TxRequestLimit uint64
+	// TxRequestLimitDuration is the time interval upon which to enforce transaction submission
+	// rate limiting.
+	TxRequestLimitDuration time.Duration
 }

services/requester/requester.go

@@ -21,6 +21,8 @@ import (
 	"github.com/onflow/go-ethereum/core/txpool"
 	"github.com/onflow/go-ethereum/core/types"
 	"github.com/rs/zerolog"
+	"github.com/sethvargo/go-limiter"
+	"github.com/sethvargo/go-limiter/memorystore"
 	"golang.org/x/sync/errgroup"
 
 	"github.com/onflow/flow-evm-gateway/config"
@@ -109,6 +111,7 @@ type EVM struct {
 	evmSigner         types.Signer
 	validationOptions *txpool.ValidationOptions
 	collector         metrics.Collector
+	rateLimiter       limiter.Store
 }
 
 func NewEVM(
@@ -165,6 +168,16 @@ func NewEVM(
 		MinTip:  new(big.Int),
 	}
 
+	rateLimiter, err := memorystore.New(
+		&memorystore.Config{
+			Tokens:   config.TxRequestLimit,
+			Interval: config.TxRequestLimitDuration,
+		},
+	)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create TX rate limiter: %w", err)
+	}
+
 	evm := &EVM{
 		registerStore:     registerStore,
 		client:            client,
@@ -177,6 +190,7 @@ func NewEVM(
 		validationOptions: validationOptions,
 		collector:         collector,
 		keystore:          keystore,
+		rateLimiter:       rateLimiter,
 	}
 
 	return evm, nil
@@ -197,6 +211,17 @@ func (e *EVM) SendRawTransaction(ctx context.Context, data []byte) (common.Hash,
 		return common.Hash{}, fmt.Errorf("failed to derive the sender: %w", err)
 	}
 
+	if e.config.TxRequestLimit > 0 {
+		_, _, _, ok, err := e.rateLimiter.Take(ctx, from.Hex())
+		if err != nil {
+			return common.Hash{}, fmt.Errorf("failed to check rate limit: %w", err)
+		}
+		if !ok {
+			e.collector.RequestRateLimited("SendRawTransaction")
+			return common.Hash{}, errs.ErrRateLimit
+		}
+	}
+
 	if tx.GasPrice().Cmp(e.config.GasPrice) < 0 {
 		return common.Hash{}, errs.NewTxGasPriceTooLowError(e.config.GasPrice)
 	}