ERR only (P)SUBSCRIBE / (P)UNSUBSCRIBE / PING / QUIT allowed in this context

[Kilowhisky]

Describe the bug
StackExchange.Redis (C#) Redis client opens a SUBSCRIBE channel as part of its normal connection process. The client then sends PING routinely on this channel to make sure its alive.

The tile38 server does not accept PING though.

tile38/internal/server/pubsub.go

Lines 329 to 349 in d7a766c

	for {
	for _, msg := range msgs {
	start = time.Now()
	var kind int
	var un bool
	switch msg.Command() {
	case "quit":
	writeOK()
	return nil
	case "psubscribe":
	kind, un = pubsubPattern, false
	case "punsubscribe":
	kind, un = pubsubPattern, true
	case "subscribe":
	kind, un = pubsubChannel, false
	case "unsubscribe":
	kind, un = pubsubChannel, true
	default:
	writeOnlyPubsubErr()
	continue
	}

Expected behavior
It should respect the PING command as the error message it sends back explicitly says it does.

tile38/internal/server/pubsub.go

Lines 218 to 228 in d7a766c

	writeOnlyPubsubErr := func() {
	switch outputType {
	case JSON:
	write([]byte(`{"ok":false` +
	`,"err":"only (P)SUBSCRIBE / (P)UNSUBSCRIBE / ` +
	`PING / QUIT allowed in this context"` +
	`,"elapsed":"` + time.Since(start).String() + `"}`))
	case RESP:
	write([]byte("-ERR only (P)SUBSCRIBE / (P)UNSUBSCRIBE / " +
	"PING / QUIT allowed in this context\r\n"))
	}

Logs

This is the error as the client closes the connection due to ProtocolError

"2023-07-06T21:53:56.6202858Z", "level": "WARN", "logger": "Tina.Tile38.Tile38ConnectionProvider", "message": "ConnectionFailed CHRIS-TOWER(SE.Redis-v2.6.116.40240) Subscription, ProtocolFailure, Unspecified/tile38-node-1.default:30512, StackExchange.Redis.RedisConnectionException: ProtocolFailure (None, last-recv: 79) on tile38-node-1.default:30512/Subscription, Idle/ComputeResult, last: PING, origin: SetResult, outstanding: 0, last-read: 0s ago, last-write: 0s ago, keep-alive: 60s, state: ConnectedEstablished, mgr: 9 of 10 available, in: 0, in-pipe: 79, out-pipe: 0, last-heartbeat: 0s ago, last-mbeat: 0s ago, global: 0s ago, v: 2.6.116.40240\r\n ---> StackExchange.Redis.RedisServerException: Error: ERR only (P)SUBSCRIBE / (P)UNSUBSCRIBE / PING / QUIT allowed in this context\r\n   --- End of inner exception stack trace ---" }

The server side appears to open and then drop the connection:

2023-07-06 14:37:42 { "time": "2023-07-06 21:37:42.6164", "level": "Info", "message": "live 192.168.65.4:34724" }
2023-07-06 14:37:42 { "time": "2023-07-06 21:37:42.6164", "level": "Debug", "message": "pubsub open" }
2023-07-06 14:37:42 { "time": "2023-07-06 21:37:42.6164", "level": "Debug", "message": "pubsub closed" }
2023-07-06 14:37:42 { "time": "2023-07-06 21:37:42.6164", "level": "Info", "message": "not live 192.168.65.4:39744" }

Operating System (please complete the following information):

• OS: Linux
• CPU: amd64
• Version: edge
• Container: Kubernetes (Docker Desktop)

[Kilowhisky]

Merged