perf(internal/blocksync): avoid double-calling types.BlockFromProto (…

…#2016)

for performance reasons.
Closes #1964

---

#### PR checklist

- [ ] ~~Tests written/updated~~
- [x] Changelog entry added in `.changelog` (we use
[unclog](https://github.com/informalsystems/unclog) to manage our
changelog)
- [x] Updated relevant documentation (`docs/` or `spec/`) and code
comments

.changelog/unreleased/improvements/2016-blocksync-avoid-double-calling-block-from-proto.md

@@ -0,0 +1,2 @@
+- `[blocksync]` Avoid double-calling `types.BlockFromProto` for performance
+  reasons ([\#2016](https://github.com/cometbft/cometbft/pull/2016))

internal/blocksync/msgs.go

@@ -30,10 +30,9 @@ func ValidateMsg(pb proto.Message) error {
 			return ErrInvalidHeight{Height: msg.Height, Reason: "negative height"}
 		}
 	case *bcproto.BlockResponse:
-		_, err := types.BlockFromProto(msg.Block)
-		if err != nil {
-			return err
-		}
+		// Avoid double-calling `types.BlockFromProto` for performance reasons.
+		// See https://github.com/cometbft/cometbft/issues/1964
+		return nil
 	case *bcproto.NoBlockResponse:
 		if msg.Height < 0 {
 			return ErrInvalidHeight{Height: msg.Height, Reason: "negative height"}

internal/blocksync/reactor.go

@@ -255,7 +255,8 @@ func (bcR *Reactor) Receive(e p2p.Envelope) {
 	case *bcproto.BlockResponse:
 		bi, err := types.BlockFromProto(msg.Block)
 		if err != nil {
-			bcR.Logger.Error("Block content is invalid", "err", err)
+			bcR.Logger.Error("Peer sent us invalid block", "peer", e.Src, "msg", e.Message, "err", err)
+			bcR.Switch.StopPeerForError(e.Src, err)
 			return
 		}
 		var extCommit *types.ExtendedCommit
@@ -266,6 +267,7 @@ func (bcR *Reactor) Receive(e p2p.Envelope) {
 				bcR.Logger.Error("failed to convert extended commit from proto",
 					"peer", e.Src,
 					"err", err)
+				bcR.Switch.StopPeerForError(e.Src, err)
 				return
 			}
 		}