Validating SSL certificate

I am doing some certificate validations, 1. I need to validate the client is presenting a certificate, I realize I can require it in the clientssl profile, but I have no log entry if I get a failed request. So I would like to do this in the irule that does the other validations based on the subject_dn, 2. I am having trouble finding information on some sample rule commands, what is: [SSL::cert 0]

 

also is SSL::cert count - what is that counting? 3. Do I want to evaluate this at CLIENTSSL_HANDSHAKE or CLIENTSSL_CLIENTCERT

 

Also this is not HTTP traffic.