[ETCM-797] add debug endpoint to request a specific block (by number) from connected peers

Author: Jaap van der Plas

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

@@ -1,9 +1,16 @@
 package io.iohk.ethereum.jsonrpc
 
-import io.iohk.ethereum.jsonrpc.DebugService.{ListPeersInfoRequest, ListPeersInfoResponse}
+import io.circe.Json.JNumber
+import io.iohk.ethereum.jsonrpc.DebugService.{
+  GetSpecificBlockRequest,
+  GetSpecificBlockResponse,
+  ListPeersInfoRequest,
+  ListPeersInfoResponse
+}
+import io.iohk.ethereum.jsonrpc.JsonRpcError.{InvalidParams, ParseError}
 import io.iohk.ethereum.jsonrpc.serialization.JsonMethodDecoder.NoParamsMethodDecoder
 import io.iohk.ethereum.jsonrpc.serialization.{JsonEncoder, JsonMethodCodec}
-import org.json4s.JsonAST.{JArray, JString, JValue}
+import org.json4s.JsonAST._
 
 object DebugJsonMethodsImplicits extends JsonMethodsImplicits {
 
@@ -12,4 +19,19 @@ object DebugJsonMethodsImplicits extends JsonMethodsImplicits {
       def encodeJson(t: ListPeersInfoResponse): JValue =
         JArray(t.peers.map(a => JString(a.toString)))
     }
+
+  implicit val debug_getSpecificBlockRequest: JsonMethodCodec[GetSpecificBlockRequest, GetSpecificBlockResponse] =
+    new JsonMethodCodec[GetSpecificBlockRequest, GetSpecificBlockResponse] {
+      override def decodeJson(
+          params: Option[JArray]
+      ): Either[JsonRpcError, GetSpecificBlockRequest] =
+        params match {
+          case Some(JArray(JInt(blockNumber) :: Nil)) =>
+            Right(GetSpecificBlockRequest(blockNumber.bigInteger))
+          case _ =>
+            Left(InvalidParams())
+        }
+
+      override def encodeJson(t: GetSpecificBlockResponse): JValue = JBool(true)
+    }
 }

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

@@ -3,20 +3,24 @@ package io.iohk.ethereum.jsonrpc
 import akka.actor.ActorRef
 import akka.util.Timeout
 import io.iohk.ethereum.jsonrpc.AkkaTaskOps._
-import io.iohk.ethereum.jsonrpc.DebugService.{ListPeersInfoRequest, ListPeersInfoResponse}
 import io.iohk.ethereum.network.EtcPeerManagerActor.{PeerInfo, PeerInfoResponse}
 import io.iohk.ethereum.network.PeerManagerActor.Peers
 import io.iohk.ethereum.network.{EtcPeerManagerActor, Peer, PeerActor, PeerId, PeerManagerActor}
+import io.iohk.ethereum.network.p2p.messages.PV62.GetBlockHeaders
 import monix.eval.Task
 
 import scala.concurrent.duration._
 
 object DebugService {
   case class ListPeersInfoRequest()
   case class ListPeersInfoResponse(peers: List[PeerInfo])
+
+  case class GetSpecificBlockRequest(number: BigInt)
+  case class GetSpecificBlockResponse()
 }
 
 class DebugService(peerManager: ActorRef, etcPeerManager: ActorRef) {
+  import DebugService._
 
   def listPeersInfo(getPeersInfoRequest: ListPeersInfoRequest): ServiceResponse[ListPeersInfoResponse] = {
     for {
@@ -41,4 +45,24 @@ class DebugService(peerManager: ActorRef, etcPeerManager: ActorRef) {
       .askFor[PeerInfoResponse](EtcPeerManagerActor.PeerInfoRequest(peer))
       .map(resp => resp.peerInfo)
   }
+
+  def getSpecificBlock(req: GetSpecificBlockRequest): ServiceResponse[GetSpecificBlockResponse] =
+    for {
+      ids <- getPeerIds
+      peers <- Task.traverse(ids)(id => getPeerInfo(id).map(id -> _))
+      eligiblePeers = peers.collect {
+        case (id, Some(peerInfo)) if peerInfo.maxBlockNumber >= req.number => id
+      }
+      _ <- Task.now {
+        eligiblePeers.foreach { peerId =>
+          peerManager.tell(
+            PeerManagerActor.SendMessage(
+              GetBlockHeaders(Left(req.number - 1), 2, 0, false),
+              peerId
+            ),
+            peerManager
+          )
+        }
+      }
+    } yield Right(GetSpecificBlockResponse())
 }

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

@@ -1,7 +1,7 @@
 package io.iohk.ethereum.jsonrpc
 
 import io.iohk.ethereum.jsonrpc.CheckpointingService._
-import io.iohk.ethereum.jsonrpc.DebugService.{ListPeersInfoRequest, ListPeersInfoResponse}
+import io.iohk.ethereum.jsonrpc.DebugService._
 import io.iohk.ethereum.jsonrpc.EthBlocksService._
 import io.iohk.ethereum.jsonrpc.EthInfoService._
 import io.iohk.ethereum.jsonrpc.EthTxService._
@@ -227,6 +227,8 @@ case class JsonRpcController(
   private def handleDebugRequest: PartialFunction[JsonRpcRequest, Task[JsonRpcResponse]] = {
     case req @ JsonRpcRequest(_, "debug_listPeersInfo", _, _) =>
       handle[ListPeersInfoRequest, ListPeersInfoResponse](debugService.listPeersInfo, req)
+    case req @ JsonRpcRequest(_, "debug_getSpecificBlock", _, _) =>
+      handle[GetSpecificBlockRequest, GetSpecificBlockResponse](debugService.getSpecificBlock, req)
   }
 
   private def handleTestRequest: PartialFunction[JsonRpcRequest, Task[JsonRpcResponse]] = {