// 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
}
func newAllocatedMap(network *net.IPNet) *allocatedMap {
firstIP, lastIP := networkdriver.NetworkRange(network)
begin := big.NewInt(0).Add(ipToBigInt(firstIP), big.NewInt(1))
end := big.NewInt(0).Sub(ipToBigInt(lastIP), big.NewInt(1))
return &allocatedMap{
p: make(map[string]struct{}),
begin: begin,
end: end,
last: big.NewInt(0).Sub(begin, big.NewInt(1)), // so first allocated will be begin
}
}
func newAllocatedMap(network *net.IPNet) *allocatedMap {
firstIP, lastIP := networkdriver.NetworkRange(network)
begin := big.NewInt(0).Add(ipToBigInt(firstIP), big.NewInt(1))
end := big.NewInt(0).Sub(ipToBigInt(lastIP), big.NewInt(1))
// if IPv4 network, then allocation range starts at begin + 1 because begin is bridge IP
if len(firstIP) == 4 {
begin = begin.Add(begin, big.NewInt(1))
}
return &allocatedMap{
p: make(map[string]struct{}),
begin: begin,
end: end,
last: big.NewInt(0).Sub(begin, big.NewInt(1)), // so first allocated will be begin
}
}
// RegisterSubnet registers network in global allocator with bounds
// defined by subnet. If you want to use network range you must call
// this method before first RequestIP, otherwise full network range will be used
func RegisterSubnet(network *net.IPNet, subnet *net.IPNet) error {
lock.Lock()
defer lock.Unlock()
key := network.String()
if _, ok := allocatedIPs[key]; ok {
return ErrNetworkAlreadyRegistered
}
n := newAllocatedMap(network)
beginIP, endIP := networkdriver.NetworkRange(subnet)
begin := big.NewInt(0).Add(ipToBigInt(beginIP), big.NewInt(1))
end := big.NewInt(0).Sub(ipToBigInt(endIP), big.NewInt(1))
// Check that subnet is within network
if !(begin.Cmp(n.begin) >= 0 && end.Cmp(n.end) <= 0 && begin.Cmp(end) == -1) {
return ErrBadSubnet
}
n.begin.Set(begin)
n.end.Set(end)
n.last.Sub(begin, big.NewInt(1))
allocatedIPs[key] = n
return nil
}
// 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)
}