Implement policy snippets

lib/policy/network.go

@@ -115,3 +115,30 @@ func (n Network) FetchPrefixes(c *http.Client) (output []net.IPNet, err error) {
 	}
 	return output, nil
 }
+
+func parseCIDROrIP(value string) (net.IPNet, error) {
+	_, ipNet, err := net.ParseCIDR(value)
+	if err != nil {
+		ip := net.ParseIP(value)
+		if ip == nil {
+			return net.IPNet{}, fmt.Errorf("failed to parse CIDR: %s", err)
+		}
+
+		if ip4 := ip.To4(); ip4 != nil {
+			return net.IPNet{
+				IP: ip4,
+				// single ip
+				Mask: net.CIDRMask(len(ip4)*8, len(ip4)*8),
+			}, nil
+		}
+		return net.IPNet{
+			IP: ip,
+			// single ip
+			Mask: net.CIDRMask(len(ip)*8, len(ip)*8),
+		}, nil
+	} else if ipNet != nil {
+		return *ipNet, nil
+	} else {
+		return net.IPNet{}, errors.New("invalid CIDR")
+	}
+}