MySQL backend: ACL query example not suited for mosquitto 1.5 and up

[synweap15]

mosquitto: 1.6.10
mosquitto-go-auth: 0.8.1 + modifications

I've followed the setup details for MySQL plugin as in README, and found ACL rejects for subscribe calls. After setting up additional logging, it seems that the acc value mosquitto is querying with is not from the [1, 2, 3] range - it's actually MOSQ_ACL_SUBSCRIBE, as defined in mosquitto_plugin.h:

#define MOSQ_ACL_NONE 0x00
#define MOSQ_ACL_READ 0x01
#define MOSQ_ACL_WRITE 0x02
#define MOSQ_ACL_SUBSCRIBE 0x04

MySQL query in README:

SELECT topic FROM acl WHERE (username = ?) AND rw >= ?

Therefore if you follow the README docs and examples and assume:

READ - 1
WRITE - 2
READWRITE - 3

you'd get git with Acl check is false upon subscription attempt since the query does not support MOSQ_ACL_SUBSCRIBE.

More information: jpmens/mosquitto-auth-plug#356
https://mosquitto.org/api/files2/mosquitto_plugin-h.html

[iegomez]

Yeah, the examples were written before MOSQ_ACL_SUBSCRIBE was introduced. I'll rewrite them along other docs on an ongoing PR.

[iegomez]

I'm adding some docs for this in a PR I'll merge in a few minutes, but in any case there's some more info in older/closed issues like #46 and #18.

Hopefully the additions to the README will help in clarifying this. Thanks again for your report and contributions!

[iegomez]

Merged!