code: func (p *passTLSClientCert) getXForwardedTLSClientCertInfo(certs []*x509.Certificate) string {
  	var headerValues []string
  
  	for _, peerCert := range certs {
  		var values []string
  		var sans string
  		var nb string
  		var na string
  
  		if p.info != nil {
  			subject := getDNInfo("Subject", p.info.subject, &peerCert.Subject)
  			if len(subject) > 0 {
  				values = append(values, subject)
  			}
  
  			issuer := getDNInfo("Issuer", p.info.issuer, &peerCert.Issuer)
  			if len(issuer) > 0 {
  				values = append(values, issuer)
  			}
  		}
  
  		ci := p.info
  		if ci != nil {
  			if ci.notBefore {
  				nb = fmt.Sprintf("NB=%d", uint64(peerCert.NotBefore.Unix()))
  				values = append(values, nb)
  			}
  			if ci.notAfter {
  				na = fmt.Sprintf("NA=%d", uint64(peerCert.NotAfter.Unix()))
  				values = append(values, na)
  			}
  
  			if ci.sans {
  				sans = fmt.Sprintf("SAN=%s", strings.Join(getSANs(peerCert), ","))
  				values = append(values, sans)
  			}
  		}
  
  		value := strings.Join(values, ",")
  		headerValues = append(headerValues, value)
  	}
  
  	return strings.Join(headerValues, ";")
  }
docs: // getXForwardedTLSClientCertInfo Build a string with the wanted client certificates information
  // like Subject="C=%s,ST=%s,L=%s,O=%s,CN=%s",NB=%d,NA=%d,SAN=%s;