sasl_getsimple_t is used to retrieve simple things from the application. In practice this is authentication name, authorization name, and realm. The
id parameter indicates which value is being requested.
Possible values include:
SASL_CB_USER - Client user identity to login as
SASL_CB_AUTHNAME - Client authentication name
SASL_CB_LANGUAGE - Comma-separated list of RFC 1766 languages
SASL_CB_CNONCE - Client-nonce (for testing mostly)