// return an available ip if one is currently available. If not,
// return the next available ip for the nextwork
func (allocated *allocatedMap) getNextIP(network *net.IPNet) (*net.IP, error) {
var (
ownIP = ipToInt(&network.IP)
first, _ = networkdriver.NetworkRange(network)
base = ipToInt(&first)
size = int(networkdriver.NetworkSize(network.Mask))
max = int32(size - 2) // size -1 for the broadcast network, -1 for the gateway network
pos = allocated.last
)
var (
firstNetIP = network.IP.To4().Mask(network.Mask)
firstAsInt = ipToInt(&firstNetIP) + 1
)
for i := int32(0); i < max; i++ {
pos = pos%max + 1
next := int32(base + pos)
if next == ownIP || next == firstAsInt {
continue
}
if _, ok := allocated.p[pos]; ok {
continue
}
allocated.p[pos] = struct{}{}
allocated.last = pos
return intToIP(next), nil
}
return nil, ErrNoAvailableIPs
}
// convert the ip into the position in the subnet. Only
// position are saved in the set
func getPosition(network *net.IPNet, ip *net.IP) int32 {
first, _ := networkdriver.NetworkRange(network)
return ipToInt(ip) - ipToInt(&first)
}