[Chore] FIx rate limit exception (#834)

Author: biandratti

src/main/scala/io/iohk/ethereum/jsonrpc/JsonRpcError.scala

@@ -2,22 +2,31 @@ package io.iohk.ethereum.jsonrpc
 
 import io.iohk.ethereum.consensus.Protocol
 import io.iohk.ethereum.jsonrpc.serialization.JsonEncoder
-import org.json4s.{JInt, JObject, JString, JValue}
+import org.json4s.{JLong, JInt, JObject, JString, JValue}
 
 case class JsonRpcError(code: Int, message: String, data: Option[JValue])
 
 // scalastyle:off magic.number
 // scalastyle:off public.methods.have.type
-object JsonRpcError {
+object JsonRpcError extends JsonMethodsImplicits {
+
   def apply[T: JsonEncoder](code: Int, message: String, data: T): JsonRpcError =
     JsonRpcError(code, message, Some(JsonEncoder[T].encodeJson(data)))
 
+  implicit val rateLimitInformation: JsonEncoder[RateLimitInformation] = (rateLimit: RateLimitInformation) =>
+    JObject(
+      "backoff_seconds" -> JLong(rateLimit.backoffSeconds)
+    )
+
   implicit val jsonRpcErrorEncoder: JsonEncoder[JsonRpcError] = err =>
     JObject(
       List("code" -> JsonEncoder.encode(err.code), "message" -> JsonEncoder.encode(err.message)) ++
         err.data.map("data" -> _)
     )
 
+  case class RateLimitInformation(backoffSeconds: Long)
+  def RateLimitError(backoffSeconds: Long) =
+    JsonRpcError(-32005, "request rate exceeded", RateLimitInformation(backoffSeconds))
   val ParseError = JsonRpcError(-32700, "An error occurred on the server while parsing the JSON text", None)
   val InvalidRequest = JsonRpcError(-32600, "The JSON sent is not a valid Request object", None)
   val MethodNotFound = JsonRpcError(-32601, "The method does not exist / is not available", None)

src/main/scala/io/iohk/ethereum/jsonrpc/server/http/JsonRpcHttpServer.scala

@@ -10,19 +10,19 @@ import ch.megard.akka.http.cors.javadsl.CorsRejection
 import ch.megard.akka.http.cors.scaladsl.CorsDirectives._
 import ch.megard.akka.http.cors.scaladsl.model.HttpOriginMatcher
 import ch.megard.akka.http.cors.scaladsl.settings.CorsSettings
+import com.typesafe.config.{Config => TypesafeConfig}
 import de.heikoseeberger.akkahttpjson4s.Json4sSupport
 import io.iohk.ethereum.faucet.jsonrpc.FaucetJsonRpcController
 import io.iohk.ethereum.jsonrpc._
-import io.iohk.ethereum.security.SSLError
 import io.iohk.ethereum.jsonrpc.serialization.JsonSerializers
 import io.iohk.ethereum.jsonrpc.server.controllers.JsonRpcBaseController
 import io.iohk.ethereum.jsonrpc.server.http.JsonRpcHttpServer.JsonRpcHttpServerConfig
+import io.iohk.ethereum.security.SSLError
 import io.iohk.ethereum.utils.{ConfigUtils, Logger}
 import javax.net.ssl.SSLContext
 import monix.eval.Task
 import monix.execution.Scheduler.Implicits.global
 import org.json4s.{DefaultFormats, JInt, native}
-import com.typesafe.config.{Config => TypesafeConfig}
 
 import scala.concurrent.duration.{FiniteDuration, _}
 
@@ -73,10 +73,14 @@ trait JsonRpcHttpServer extends Json4sSupport with RateLimit with Logger {
   }
 
   def handleRateLimitedRequest(clientAddress: RemoteAddress, request: JsonRpcRequest): StandardRoute = {
-    if (isBelowRateLimit(clientAddress)) {
-      log.warn(s"Request limit exceeded for ip ${clientAddress.toIP.getOrElse("unknown")}")
+    if (isBelowRateLimit(clientAddress))
       complete(jsonRpcController.handleRequest(request).runToFuture)
-    } else complete(StatusCodes.TooManyRequests)
+    else {
+      log.warn(s"Request limit exceeded for ip ${clientAddress.toIP.getOrElse("unknown")}")
+      complete(
+        (StatusCodes.TooManyRequests, JsonRpcError.RateLimitError(config.rateLimit.minRequestInterval.toSeconds))
+      )
+    }
   }
 
   /**
@@ -113,7 +117,7 @@ trait JsonRpcHttpServer extends Json4sSupport with RateLimit with Logger {
           .traverse(requests)(request => jsonRpcController.handleRequest(request))
           .runToFuture
       }
-    } else complete(StatusCodes.MethodNotAllowed)
+    } else complete(StatusCodes.MethodNotAllowed, JsonRpcError.MethodNotFound)
   }
 }