Reject out of date blocks submitted via RPC (#1914)

* Disallow by default RPC submission of out of date blocks (blocks which are out of virtual DAA window)

* go fmt

* Better condition test

* Make allowNonDAABlocks an RPC field and not a command line flag

* go fmt

* one more go fmt

app/appmessage/rpc_submit_block.go

@@ -4,7 +4,8 @@ package appmessage
 // its respective RPC message
 type SubmitBlockRequestMessage struct {
 	baseMessage
-	Block *RPCBlock
+	Block             *RPCBlock
+	AllowNonDAABlocks bool
 }
 
 // Command returns the protocol command string for the message

app/rpc/rpchandlers/submit_block.go

@@ -34,6 +34,23 @@ func HandleSubmitBlock(context *rpccontext.Context, _ *router.Router, request ap
 		}, nil
 	}
 
+	if !submitBlockRequest.AllowNonDAABlocks {
+		virtualDAAScore, err := context.Domain.Consensus().GetVirtualDAAScore()
+		if err != nil {
+			return nil, err
+		}
+		// A simple heuristic check which signals that the mined block is out of date
+		// and should not be accepted unless user explicitly requests
+		daaWindowSize := uint64(context.Config.NetParams().DifficultyAdjustmentWindowSize)
+		if virtualDAAScore > daaWindowSize && domainBlock.Header.DAAScore() < virtualDAAScore-daaWindowSize {
+			return &appmessage.SubmitBlockResponseMessage{
+				Error: appmessage.RPCErrorf("Block rejected. Reason: block DAA score %d is too far "+
+					"behind virtual's DAA score %d", domainBlock.Header.DAAScore(), virtualDAAScore),
+				RejectReason: appmessage.RejectReasonBlockInvalid,
+			}, nil
+		}
+	}
+
 	err = context.ProtocolManager.AddBlock(domainBlock)
 	if err != nil {
 		isProtocolOrRuleError := errors.As(err, &ruleerrors.RuleError{}) || errors.As(err, &protocolerrors.ProtocolError{})

infrastructure/network/netadapter/server/grpcserver/protowire/rpc.proto

@@ -129,6 +129,7 @@ message GetCurrentNetworkResponseMessage{
 // See: GetBlockTemplateRequestMessage
 message SubmitBlockRequestMessage{
   RpcBlock block = 2;
+  bool allowNonDAABlocks = 3;
 }
 
 message SubmitBlockResponseMessage{

infrastructure/network/netadapter/server/grpcserver/protowire/rpc_submit_block.go

@@ -27,7 +27,8 @@ func (x *SubmitBlockRequestMessage) toAppMessage() (appmessage.Message, error) {
 		return nil, err
 	}
 	return &appmessage.SubmitBlockRequestMessage{
-		Block: blockAppMessage,
+		Block:             blockAppMessage,
+		AllowNonDAABlocks: x.GetAllowNonDAABlocks(),
 	}, nil
 }