Authentication issue with Predixy server

[l2dy]

Version

4.3.5

Context

I encountered an authentication issue when connecting to a Predixy-proxied Redis cluster.

Do you have a reproducer?

No, but could provide one if requested.

Steps to reproduce

1. Configure a predixy cluster with authentication enabled.
2. Connect to the proxy with a Redis URI containing the password.
3. Issue a PING command via Vert.x Redis client.
4. Get ERR auth permission deny error.

Extra

vertx-redis-client/src/main/java/io/vertx/redis/client/impl/RedisConnectionManager.java

Lines 295 to 297 in e4609d6

	if (err instanceof ErrorType) {
	if (((ErrorType) err).is("NOAUTH")) {
	// old authentication required

The Redis connection manager in Vert.x Redis client expects the server to return NOAUTH for an unauthenticated client if HELLO is not recognized by the server. Predixy, however, returns an error of type ERR, so old-style authentication is not attempted at all in the ping() method.

Is it possible to attempt old-style authentication before attempting to PING the server if password is set?

Full error message from Predixy is ERR auth permission deny, as shown in https://github.com/joyieldInc/predixy/blob/c15f54e274afc596b8e8cd7fecac70164c95b9ec/src/Response.cpp#L27.