Auth plugin NEVER receive callback when using password_file

[kuldeepdhaka]

As per https://mosquitto.org/man/mosquitto-conf-5.html "If password_file, or acl_file are used in the config file alongsize auth_plugin, the plugin checks will run after the build in checks."

https://github.com/eclipse/mosquitto/blob/2d360fd49521ef8c1694288023f93cc605697189/src/security_default.c#L833-L886

In above code, if no user is found (having a hash table), mosquitto_unpwd_check_default() return MOSQ_ERR_AUTH (the last line of function)

shouldn't it actually return MOSQ_ERR_PLUGIN_DEFER (at last line) since it suppose to defer it to other as per the docs)?

mosquitto_auth_unpwd_check() will never receive the callback if password_file is used in mosquitto.conf

Note: im very new to the code and based on heuristic this fixes my auth plugin not getting any callback.

diff --git a/src/security_default.c b/src/security_default.c
index 99b7809..8f896b0 100644
--- a/src/security_default.c
+++ b/src/security_default.c
@@ -882,7 +882,7 @@ int mosquitto_unpwd_check_default(struct mosquitto_db *db, struct mosquitto *con
        }
    }

-   return MOSQ_ERR_AUTH;
+   return MOSQ_ERR_PLUGIN_DEFER;
 }

 static int unpwd__cleanup(struct mosquitto__unpwd **root, bool reload)

[ralight]

You're right (as in the PR), but it does need more work to fix properly and won't be in 1.6.