eap/tls questions with freeradius

Hi , i've got a question : i've set up a freeradius server with EAP/TLS. In my configuration, i use check_cert_issuer in order to check certificate. Is there any functions wich allows me to check client's certificate subject (C,O,OU ??) ? Further more, i got an other question : when a client requests authentication, server checks before users file then certificate validity of a client ? Cheers