irule compatible for v11.2.1

Hi All ,

I am having an irule which is in BIG-IP 11.4.1 Build 637.0. Currently I need to apply this rule in BIG-IP 11.2.1 Build 797.0 Final

Please help me with the correct syntax which will work in v11

Below is the irule:

when RULE_INIT { set ::org "O=Akamai"

log "Hello there ..."

}

when CLIENTSSL_CLIENTCERT {

Check if client provided a cert if {[SSL::cert 0] eq ""}{ log "No SSL Certificate sent, rejecting..." Reset the connection reject

} else {

  set subject_dn [X509::subject [SSL::cert 0]]
  log "Client Certificate Received: $subject_dn"
  Check if the client certificate contains the correct CN from the list
  if { ([class match $subject_dn contains cbr_cn_stage]) } {
     Accept the client cert
     log "Client Certificate Accepted: $subject_dn"
  } else {
     log "No Matching Client Certificate Was Found Using: $subject_dn"
     reject
  }

} }

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Getting below error while applying the same in BIG-IP 11.2.1 Build 797.0 Final:

01070151:3: Rule [/Common/iRule_CBR_CN_PROD_Validation] error: Unable to find value_list (cbr_cn_stage) referenced at line 19: [class match $subject_dn contains cbr_cn_stage]

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thanks