fix(multiplayer): bound websocket writes

server/api/events_test.go

@@ -3,6 +3,7 @@ package api
 import (
 	"bufio"
 	"bytes"
+	"net"
 	"net/http"
 	"net/http/httptest"
 	"testing"
@@ -25,6 +26,24 @@ func TestWebSocketReaderRejectsOversizedControlFrame(t *testing.T) {
 	}
 }
 
+func TestWebSocketWriterDoesNotBlockForeverOnSlowClient(t *testing.T) {
+	sender, receiver := net.Pipe()
+	defer sender.Close()
+	defer receiver.Close()
+	done := make(chan error, 1)
+	go func() {
+		done <- writeWebSocketFrameWithDeadline(sender, 0x1, bytes.Repeat([]byte{'x'}, maxWebSocketFrame), 20*time.Millisecond)
+	}()
+	select {
+	case err := <-done:
+		if err == nil {
+			t.Fatal("write to a non-reading client unexpectedly succeeded")
+		}
+	case <-time.After(time.Second):
+		t.Fatal("write to a non-reading client blocked past its deadline")
+	}
+}
+
 func TestWebSocketHandshakeRequiresRFC6455Version(t *testing.T) {
 	service := &Service{}
 	request := httptest.NewRequest(http.MethodGet, "/v1/events", nil)