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allocator.go
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allocator.go
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// Package ipallocator defines the default IP allocator. It will move out of libnetwork as an external IPAM plugin.
// This has been imported unchanged from Docker, besides additon of registration logic
package ipallocator
import (
"errors"
"math/big"
"net"
"sync"
"github.com/Sirupsen/logrus"
"github.com/docker/libnetwork/netutils"
)
// allocatedMap is thread-unsafe set of allocated IP
type allocatedMap struct {
p map[string]struct{}
last *big.Int
begin *big.Int
end *big.Int
}
func newAllocatedMap(network *net.IPNet) *allocatedMap {
firstIP, lastIP := netutils.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
}
}
type networkSet map[string]*allocatedMap
var (
// ErrNoAvailableIPs preformatted error
ErrNoAvailableIPs = errors.New("no available ip addresses on network")
// ErrIPAlreadyAllocated preformatted error
ErrIPAlreadyAllocated = errors.New("ip already allocated")
// ErrIPOutOfRange preformatted error
ErrIPOutOfRange = errors.New("requested ip is out of range")
// ErrNetworkAlreadyRegistered preformatted error
ErrNetworkAlreadyRegistered = errors.New("network already registered")
// ErrBadSubnet preformatted error
ErrBadSubnet = errors.New("network does not contain specified subnet")
)
// IPAllocator manages the ipam
type IPAllocator struct {
allocatedIPs networkSet
mutex sync.Mutex
}
// New returns a new instance of IPAllocator
func New() *IPAllocator {
return &IPAllocator{networkSet{}, sync.Mutex{}}
}
// 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 (a *IPAllocator) RegisterSubnet(network *net.IPNet, subnet *net.IPNet) error {
a.mutex.Lock()
defer a.mutex.Unlock()
nw := &net.IPNet{IP: network.IP.Mask(network.Mask), Mask: network.Mask}
key := nw.String()
if _, ok := a.allocatedIPs[key]; ok {
return ErrNetworkAlreadyRegistered
}
// Check that subnet is within network
beginIP, endIP := netutils.NetworkRange(subnet)
if !(network.Contains(beginIP) && network.Contains(endIP)) {
return ErrBadSubnet
}
n := newAllocatedMap(subnet)
a.allocatedIPs[key] = n
return nil
}
// RequestIP requests an available ip from the given network. It
// will return the next available ip if the ip provided is nil. If the
// ip provided is not nil it will validate that the provided ip is available
// for use or return an error
func (a *IPAllocator) RequestIP(network *net.IPNet, ip net.IP) (net.IP, error) {
a.mutex.Lock()
defer a.mutex.Unlock()
nw := &net.IPNet{IP: network.IP.Mask(network.Mask), Mask: network.Mask}
key := nw.String()
allocated, ok := a.allocatedIPs[key]
if !ok {
allocated = newAllocatedMap(nw)
a.allocatedIPs[key] = allocated
}
if ip == nil {
return allocated.getNextIP()
}
return allocated.checkIP(ip)
}
// ReleaseIP adds the provided ip back into the pool of
// available ips to be returned for use.
func (a *IPAllocator) ReleaseIP(network *net.IPNet, ip net.IP) error {
a.mutex.Lock()
defer a.mutex.Unlock()
nw := &net.IPNet{IP: network.IP.Mask(network.Mask), Mask: network.Mask}
if allocated, exists := a.allocatedIPs[nw.String()]; exists {
delete(allocated.p, ip.String())
}
return nil
}
func (allocated *allocatedMap) checkIP(ip net.IP) (net.IP, error) {
if _, ok := allocated.p[ip.String()]; ok {
return nil, ErrIPAlreadyAllocated
}
pos := ipToBigInt(ip)
// Verify that the IP address is within our network range.
if pos.Cmp(allocated.begin) == -1 || pos.Cmp(allocated.end) == 1 {
return nil, ErrIPOutOfRange
}
// Register the IP.
allocated.p[ip.String()] = struct{}{}
return ip, nil
}
// return an available ip if one is currently available. If not,
// return the next available ip for the network
func (allocated *allocatedMap) getNextIP() (net.IP, error) {
pos := big.NewInt(0).Set(allocated.last)
allRange := big.NewInt(0).Sub(allocated.end, allocated.begin)
for i := big.NewInt(0); i.Cmp(allRange) <= 0; i.Add(i, big.NewInt(1)) {
pos.Add(pos, big.NewInt(1))
if pos.Cmp(allocated.end) == 1 {
pos.Set(allocated.begin)
}
if _, ok := allocated.p[bigIntToIP(pos).String()]; ok {
continue
}
allocated.p[bigIntToIP(pos).String()] = struct{}{}
allocated.last.Set(pos)
return bigIntToIP(pos), nil
}
return nil, ErrNoAvailableIPs
}
// Converts a 4 bytes IP into a 128 bit integer
func ipToBigInt(ip net.IP) *big.Int {
x := big.NewInt(0)
if ip4 := ip.To4(); ip4 != nil {
return x.SetBytes(ip4)
}
if ip6 := ip.To16(); ip6 != nil {
return x.SetBytes(ip6)
}
logrus.Errorf("ipToBigInt: Wrong IP length! %s", ip)
return nil
}
// Converts 128 bit integer into a 4 bytes IP address
func bigIntToIP(v *big.Int) net.IP {
return net.IP(v.Bytes())
}