Selective Client Cert Authentication iRule

I have found a few references to iRules used to require client SSL certificates for selective URIs on a site. Am quite new to iRules and having trouble picking out the bits I need to do the job. What I would like to achieve is:

 

 

Use a class map to specify URIs which require a client cert.

 

Check if client cert is present and that it is valid.

 

If there is no valid client cert, send a HTTP 403.7 error to advise user that a certificate is required.

 

If client cert exists and is valid, allow access to the application.

 

 

I am sure this quite simple to achieve, any help would be greatly appreciated.

 

 

Many thanks,

 

 

Becky