BroadcastOperator.fetchSockets() ignores flags

[schw4rzlicht]

Describe the bug

When using BroadcastOperator.fetchSockets(), flags that were set before (e.g. with io.local.fetchSockets() → sets local: true flag) are ignored.

This leads to all sockets across all nodes being returned for example instead of only the local ones.

I suspect this code to be responsible:

socket.io/lib/broadcast-operator.ts

Lines 262 to 265 in 8ecfcba

	.fetchSockets({
	rooms: this.rooms,
	except: this.exceptRooms,
	})

To Reproduce

Socket.IO server version: 4.4.1

Server

see https://github.com/fan711/socket-server

Socket.IO client version: 4.4.1

Client

see https://github.com/fan711/socket-client

Expected behavior

Previously set flags on BroadcastOperator should be respected. I'd suggest following change but I am not sure about any implications this might have, thus opening this as an issue instead of a PR:

      .fetchSockets({
        rooms: this.rooms,
        except: this.exceptRooms,
+       flags: this.flags,
      })

Additional context

Initially suspected https://github.com/socketio/socket.io-redis-adapter and opened socketio/socket.io-redis-adapter#454 but I am happy to close that one if this one here is confirmed.

/cc @fan711

[derikb]

Would I think, save us some crazy extra redis usage if this could get released (please, thank you). Our pubsub traffic went a bit crazy when we updated to 4 and I think this is at least one of the causes. (Thanks for noticing this @schw4rzlicht and thanks for fixing it @darrachequesne )

[darrachequesne]

Letseee go: https://github.com/socketio/socket.io/releases/tag/4.5.1