blockRange feature to configure transaction max block (#160)

server/request_processor.go

@@ -312,6 +312,18 @@ func (r *RpcRequest) sendTxToRelay() {
 		}
 	}
 
+	if r.urlParams.blockRange > 0 {
+		bn, err := r.defaultEthClient.BlockNumber(context.Background())
+		if err != nil {
+			r.logger.Error("[sendTxToRelay] BlockNumber failed", "error", err)
+			r.writeRpcError(err.Error(), types.JsonRpcInternalError)
+			return
+		}
+		// this actually means that we use blockRange+1, to avoid problems with lagging blocks etc.
+		maxBlockNumber := bn + 1 + uint64(r.urlParams.blockRange)
+		sendPrivateTxArgs.MaxBlockNumber = maxBlockNumber
+	}
+
 	fbRpc := flashbotsrpc.New(r.relayUrl, func(rpc *flashbotsrpc.FlashbotsRPC) {
 		if r.urlParams.originId != "" {
 			rpc.Headers["X-Flashbots-Origin"] = r.urlParams.originId

server/url_params.go

@@ -15,6 +15,7 @@ var (
 	DefaultAuctionHint = []string{"hash", "special_logs"}
 
 	ErrIncorrectMempoolURL                 = errors.New("Incorrect mempool URL.")
+	ErrIncorrectURLParam                   = errors.New("Incorrect URL parameter")
 	ErrEmptyHintQuery                      = errors.New("Hint query must be non-empty if set.")
 	ErrEmptyTargetBuilderQuery             = errors.New("Target builder query must be non-empty if set.")
 	ErrIncorrectAuctionHints               = errors.New("Incorrect auction hint, must be one of: contract_address, function_selector, logs, calldata, default_logs.")
@@ -30,6 +31,7 @@ type URLParameters struct {
 	prefWasSet bool
 	originId   string
 	fast       bool
+	blockRange int
 }
 
 // normalizeQueryParams takes a URL and returns a map of query parameters with all keys normalized to lowercase.
@@ -169,6 +171,14 @@ func ExtractParametersFromUrl(reqUrl *url.URL, allBuilders []string) (params URL
 		parsedUrl.Scheme = "https"
 		params.pref.Privacy.MempoolRPC = parsedUrl.String()
 	}
+	blockRange := normalizedQuery["blockrange"]
+	if len(blockRange) != 0 {
+		brange, err := strconv.Atoi(blockRange[0])
+		if err != nil {
+			return params, ErrIncorrectURLParam
+		}
+		params.blockRange = brange
+	}
 
 	return params, nil
 }

types/types.go

@@ -107,8 +107,9 @@ type BundleResponse struct {
 }
 
 type SendPrivateTxRequestWithPreferences struct {
-	Tx          string                `json:"tx"`
-	Preferences *PrivateTxPreferences `json:"preferences,omitempty"`
+	Tx             string                `json:"tx"`
+	Preferences    *PrivateTxPreferences `json:"preferences,omitempty"`
+	MaxBlockNumber uint64                `json:"maxBlockNumber"`
 }
 
 type TxPrivacyPreferences struct {