The commit introduces the following API incompatibilities:
In ejabberd_auth.erl:
* dirty_get_registered_users/0 is renamed to get_users/0
* get_vh_registered_users/1 is renamed to get_users/1
* get_vh_registered_users/2 is renamed to get_users/2
* get_vh_registered_users_number/1 is renamed to count_users/1
* get_vh_registered_users_number/2 is renamed to count_users/2
In ejabberd_auth callbacks
* plain_password_required/0 is replaced by plain_password_required/1
where the argument is a virtual host
* store_type/0 is replaced by store_type/1 where the argument is
a virtual host
* set_password/3 is now an optional callback
* remove_user/3 callback is no longer needed
* remove_user/2 now should return `ok | {error, atom()}`
* is_user_exists/2 now must only be implemented for backends
with `external` store type
* check_password/6 is no longer needed
* check_password/4 now must only be implemented for backends
with `external` store type
* try_register/3 is now an optional callback and should return
`ok | {error, atom()}`
* dirty_get_registered_users/0 is no longer needed
* get_vh_registered_users/1 is no longer needed
* get_vh_registered_users/2 is renamed to get_users/2
* get_vh_registered_users_number/1 is no longer needed
* get_vh_registered_users_number/2 is renamed to count_users/2
* get_password_s/2 is no longer needed
* get_password/2 now must only be implemented for backends with
`plain` or `scram` store type
Additionally, the commit introduces two new callbacks:
* use_cache/1 where the argument is a virtual host
* cache_nodes/1 where the argument is a virtual host
New options are also introduced: `auth_use_cache`, `auth_cache_missed`,
`auth_cache_life_time` and `auth_cache_size`.
This allows the authentication modules to perform SASL proxy authentication. It puts the onus on them to authorize the authcid to masquerade as the authzid. Doesn't currently implement such functionality in existing auth modules, since they cannot currently codify a relationship between the two identities. Does not permit the authzid to use a domain differently from the one of the connection.
Note: digest might not work, but I have no interest in it, being deprecated.
