don't show field if no san information

certify.go

@@ -143,16 +143,19 @@ func CertInfo(cert *x509.Certificate) string {
 	buf.WriteString(fmt.Sprintf("%16s%v\n", "", parseExtKeyUsage(cert.ExtKeyUsage)))
 	buf.WriteString(fmt.Sprintf("%8sX509v3 Basic Constraints:\n", ""))
 	buf.WriteString(fmt.Sprintf("%12sCA: %v\n", "", cert.IsCA))
-	buf.WriteString(fmt.Sprintf("%8sX509v3 Subject Alternative Name:\n", ""))
-	if len(cert.IPAddresses) != 0 {
-		var ips []string
-		for _, ip := range cert.IPAddresses {
-			ips = append(ips, ip.String())
+
+	if len(cert.IPAddresses) != 0 || len(cert.DNSNames) != 0 {
+		buf.WriteString(fmt.Sprintf("%8sX509v3 Subject Alternative Name:\n", ""))
+		if len(cert.IPAddresses) != 0 {
+			var ips []string
+			for _, ip := range cert.IPAddresses {
+				ips = append(ips, ip.String())
+			}
+			buf.WriteString(fmt.Sprintf("%12sIP Address: %v\n", "", strings.Join(ips, ", ")))
+		}
+		if len(cert.DNSNames) != 0 {
+			buf.WriteString(fmt.Sprintf("%12sDNS: %v\n", "", strings.Join(cert.DNSNames, ", ")))
 		}
-		buf.WriteString(fmt.Sprintf("%12sIP Address: %v\n", "", strings.Join(ips, ", ")))
-	}
-	if len(cert.DNSNames) != 0 {
-		buf.WriteString(fmt.Sprintf("%12sDNS: %v\n", "", strings.Join(cert.DNSNames, ", ")))
 	}
 
 	buf.WriteString(fmt.Sprintf("%8sSignature Algorithm: %v\n", "", cert.SignatureAlgorithm))

helper.go

@@ -12,11 +12,11 @@ func parseExtKeyUsage(ekus []x509.ExtKeyUsage) string {
 
 	for _, eku := range ekus {
 		if eku == x509.ExtKeyUsageAny {
-			extku = append(extku, "ExtKeyUsageAny")
+			extku = append(extku, "Any Usage")
 		} else if eku == x509.ExtKeyUsageClientAuth {
-			extku = append(extku, "ExtKeyUsageClientAuth")
+			extku = append(extku, "TLS Web Client Authentication")
 		} else if eku == x509.ExtKeyUsageServerAuth {
-			extku = append(extku, "ExtKeyUsageServerAuth")
+			extku = append(extku, "TLS Web Server Authentication")
 		} else {
 			extku = append(extku, strconv.Itoa(int(eku)))
 		}