sasl_authorize_t(3) -- Linux man page
NAMEsasl_authorize_t - The SASL authorization callback
#include <sasl/sasl.h> int sasl_authorize_t(void *context, const char *requested_user, unsigned alen, const char *auth_identity, unsigned alen, const char *def_realm, unsigned urlen, struct propctx *propctx)
sasl_authorize_t is used to check whether the authorized user auth_identity may act as the user requested_user. For example the user root may wish to authenticate with his credentials but act as the user tmartin (with all of tmartin's rights not roots). A server application should be very careful, and probably err on the side of caution, when determining which users may proxy as whom.