Modifying HTTP header on the basis of SSL certificate

This is better!

when CLIENTSSL_CLIENTCERT {  
  set debug 0

   Check if client provided a cert  
    if {[SSL::cert 0] eq ""}{  
      Reset the connection if no cert present 
         reject 
    } else {  
      Example Subject DN:  /C=AU/ST=NSW/L=Syd/O=Your Organisation/OU=Your OU/CN=John Smith  
       set ssl_cert [SSL::cert 0]    
       set subject_dn [X509::subject [SSL::cert 0]]}
       set issuer [X509::issuer $ssl_cert]   
         Check if the certificate contains valid CN 
       if { ($issuer contains "Origo Root CA - G2M")  or ($issuer contains "OSIS Customer CA")} {  
          Accept the client cert  
          log "Client Certificate Accepted:$issuer" 
       } else {  
          log "No Matching Client Certificate Was Found Using: Cert issuer - [X509::issuer $ssl_cert]" 
             reject  
               }
        }

 Then re-write HOST name

when HTTP_REQUEST {  
    set requestedhost [string tolower [HTTP::host]]
    set requestedURI [HTTP::uri]
    set content_length [HTTP::header "Content-Length"]
    set method [HTTP::method]

       log "ip address=[IP::client_addr] before cookie HTTP method=$method host=$requestedhost uri=$requestedURI payload=[HTTP::payload] content length=$content_length"
    if { $requestedhost equals "test1.domain.com"} {
        HTTP::header replace Host "test2.newdomain.com"
        HTTP::header insert "CIACertHeader" [X509::whole  [SSL::cert 0]]
    HTTP::cookie insert name "BIGIPCOOKIE" value BIGIPTEST
    virtual VIRTUAL_SERVER_HTTPS                        
           log local0. "after cookie cookie host=[HTTP::host] uri=[HTTP::uri]  cert[X509::whole [SSL::cert 0]] "
  }
}