func parseEphemeralPorts()

in tcpdumpw/main.go [574:605]

• 24 lines of code
• 10 McCabe index (conditional complexity)

func parseEphemeralPorts(ephemerals *string) *pcap.PcapEphemeralPorts {
	// default ephemeral ports range
	ephemeralPortRange := &pcap.PcapEphemeralPorts{
		Min: pcap.PCAP_MIN_EPHEMERAL_PORT,
		Max: pcap.PCAP_MAX_EPHEMERAL_PORT,
	}

	if *ephemerals == "" {
		return ephemeralPortRange
	}

	ephemeralPorts := strings.SplitN(*ephemerals, ",", 2)

	if len(ephemeralPorts) != 2 {
		return ephemeralPortRange
	}

	for i, valueStr := range ephemeralPorts {
		if value, err := strconv.ParseUint(valueStr, 10, 16); err != nil && value >= 0x0400 && value <= 0xFFFF {
			// see: https://datatracker.ietf.org/doc/html/rfc6056#page-5
			// a valid `ephemeral port` must be within RFC 6056 range: [1024/0x4000,65535/0xFFFF]
			port := uint16(value)
			if i == 0 && port < ephemeralPortRange.Max {
				ephemeralPortRange.Min = uint16(value)
			} else if port > ephemeralPortRange.Min {
				ephemeralPortRange.Max = uint16(value)
			}
		}
	}

	return ephemeralPortRange
}