9 "github.com/edwarnicke/exechelper"
12 type AddressCounter = int
14 type Ip4AddressAllocator struct {
15 networks map[int]AddressCounter
20 func (a *Ip4AddressAllocator) AddNetwork(networkNumber int) {
21 a.networks[networkNumber] = 1
24 func (a *Ip4AddressAllocator) NewIp4InterfaceAddress(inputNetworkNumber ...int) (string, error) {
25 var networkNumber int = 0
26 if len(inputNetworkNumber) > 0 {
27 networkNumber = inputNetworkNumber[0]
30 if _, ok := a.networks[networkNumber]; !ok {
31 a.AddNetwork(networkNumber)
34 numberOfAddresses := a.networks[networkNumber]
36 if numberOfAddresses == 254 {
37 return "", fmt.Errorf("no available IPv4 addresses")
40 address, err := a.createIpAddress(networkNumber, numberOfAddresses)
42 a.networks[networkNumber] = numberOfAddresses + 1
44 return address + "/24", err
47 // Creates a file every time an IP is assigned: used to keep track of addresses in use.
48 // If an address is not in use, 'counter' is then copied to 'chosenOctet' and it is used for the remaining tests.
49 // Also checks host IP addresses.
50 func (a *Ip4AddressAllocator) createIpAddress(networkNumber int, numberOfAddresses int) (string, error) {
51 hostIps, _ := exechelper.CombinedOutput("ip a")
56 if a.chosenOctet != 0 {
57 address = fmt.Sprintf("10.%v.%v.%v", a.chosenOctet, networkNumber, numberOfAddresses)
58 file, err := os.Create(address)
60 return "", errors.New("unable to create file: " + fmt.Sprint(err))
65 address = fmt.Sprintf("10.%v.%v.%v", counter, networkNumber, numberOfAddresses)
66 _, err := os.Stat(address)
67 if err == nil || strings.Contains(string(hostIps), address) {
69 } else if os.IsNotExist(err) {
70 file, err := os.Create(address)
72 return "", errors.New("unable to create file: " + fmt.Sprint(err))
75 a.chosenOctet = counter
78 return "", errors.New("an error occurred while checking if a file exists: " + fmt.Sprint(err))
83 a.assignedIps = append(a.assignedIps, address)
87 func (a *Ip4AddressAllocator) deleteIpAddresses() {
88 for ip := range a.assignedIps {
89 os.Remove(a.assignedIps[ip])
93 func NewIp4AddressAllocator() *Ip4AddressAllocator {
94 var ip4AddrAllocator = new(Ip4AddressAllocator)
95 ip4AddrAllocator.networks = make(map[int]AddressCounter)
96 ip4AddrAllocator.AddNetwork(0)
97 return ip4AddrAllocator