func DeconstructIPsFromPrefix()

in pkg/utils/helper.go [168:204]

• 29 lines of code
• 8 McCabe index (conditional complexity)

func DeconstructIPsFromPrefix(prefix string) ([]string, error) {
	var deconstructedIPs []string

	// find the index of / in prefix
	index := strings.Index(prefix, "/")
	if index < 0 {
		return nil, fmt.Errorf("invalid IPv4 prefix %v", prefix)
	}

	// construct network address
	addr := strings.Split(prefix[:index], ".")
	if addr == nil || len(addr) != 4 {
		return nil, fmt.Errorf("invalid IPv4 prefix %v", prefix)
	}
	networkAddr := addr[0] + "." + addr[1] + "." + addr[2] + "."

	// get mask and calculate number of IPv4 addresses in the range
	mask, err := strconv.Atoi(prefix[index+1:])
	if err != nil {
		return nil, err
	}
	if mask < 0 || mask > 32 {
		return nil, fmt.Errorf("invalid IPv4 prefix %v", prefix)
	}
	numOfAddresses := IntPower(2, 32-mask)

	// concatenate network addr and host addr to get /32 IPv4 address
	for i := 0; i < numOfAddresses; i++ {
		hostAddr, err := strconv.Atoi(addr[3])
		if err != nil {
			return nil, err
		}
		ipAddr := networkAddr + strconv.Itoa(hostAddr+i) + "/32"
		deconstructedIPs = append(deconstructedIPs, ipAddr)
	}
	return deconstructedIPs, nil
}