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allocator.go
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allocator.go
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// Copyright 2015 CNI authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package allocator
import (
"fmt"
"log"
"net"
"os"
"github.com/containernetworking/cni/pkg/ip"
"github.com/containernetworking/cni/pkg/types"
"github.com/containernetworking/cni/pkg/types/current"
"github.com/containernetworking/cni/plugins/ipam/host-local/backend"
)
type IPAllocator struct {
// start is inclusive and may be allocated
start net.IP
// end is inclusive and may be allocated
end net.IP
conf *IPAMConfig
store backend.Store
}
func NewIPAllocator(conf *IPAMConfig, store backend.Store) (*IPAllocator, error) {
// Can't create an allocator for a network with no addresses, eg
// a /32 or /31
ones, masklen := conf.Subnet.Mask.Size()
if ones > masklen-2 {
return nil, fmt.Errorf("Network %v too small to allocate from", conf.Subnet)
}
var (
start net.IP
end net.IP
err error
)
start, end, err = networkRange((*net.IPNet)(&conf.Subnet))
if err != nil {
return nil, err
}
// skip the .0 address
start = ip.NextIP(start)
if conf.RangeStart != nil {
if err := validateRangeIP(conf.RangeStart, (*net.IPNet)(&conf.Subnet), nil, nil); err != nil {
return nil, err
}
start = conf.RangeStart
}
if conf.RangeEnd != nil {
if err := validateRangeIP(conf.RangeEnd, (*net.IPNet)(&conf.Subnet), start, nil); err != nil {
return nil, err
}
end = conf.RangeEnd
}
return &IPAllocator{start, end, conf, store}, nil
}
func canonicalizeIP(ip net.IP) (net.IP, error) {
if ip.To4() != nil {
return ip.To4(), nil
} else if ip.To16() != nil {
return ip.To16(), nil
}
return nil, fmt.Errorf("IP %s not v4 nor v6", ip)
}
// Ensures @ip is within @ipnet, and (if given) inclusive of @start and @end
func validateRangeIP(ip net.IP, ipnet *net.IPNet, start net.IP, end net.IP) error {
var err error
// Make sure we can compare IPv4 addresses directly
ip, err = canonicalizeIP(ip)
if err != nil {
return err
}
if !ipnet.Contains(ip) {
return fmt.Errorf("%s not in network: %s", ip, ipnet)
}
if start != nil {
start, err = canonicalizeIP(start)
if err != nil {
return err
}
if len(ip) != len(start) {
return fmt.Errorf("%s %d not same size IP address as start %s %d", ip, len(ip), start, len(start))
}
for i := 0; i < len(ip); i++ {
if ip[i] > start[i] {
break
} else if ip[i] < start[i] {
return fmt.Errorf("%s outside of network %s with start %s", ip, ipnet, start)
}
}
}
if end != nil {
end, err = canonicalizeIP(end)
if err != nil {
return err
}
if len(ip) != len(end) {
return fmt.Errorf("%s %d not same size IP address as end %s %d", ip, len(ip), end, len(end))
}
for i := 0; i < len(ip); i++ {
if ip[i] < end[i] {
break
} else if ip[i] > end[i] {
return fmt.Errorf("%s outside of network %s with end %s", ip, ipnet, end)
}
}
}
return nil
}
// Returns newly allocated IP along with its config
func (a *IPAllocator) Get(id string) (*current.IPConfig, []*types.Route, error) {
a.store.Lock()
defer a.store.Unlock()
gw := a.conf.Gateway
if gw == nil {
gw = ip.NextIP(a.conf.Subnet.IP)
}
var requestedIP net.IP
if a.conf.Args != nil {
requestedIP = a.conf.Args.IP
}
if requestedIP != nil {
if gw != nil && gw.Equal(a.conf.Args.IP) {
return nil, nil, fmt.Errorf("requested IP must differ gateway IP")
}
subnet := net.IPNet{
IP: a.conf.Subnet.IP,
Mask: a.conf.Subnet.Mask,
}
err := validateRangeIP(requestedIP, &subnet, a.start, a.end)
if err != nil {
return nil, nil, err
}
reserved, err := a.store.Reserve(id, requestedIP)
if err != nil {
return nil, nil, err
}
if reserved {
ipConfig := ¤t.IPConfig{
Version: "4",
Address: net.IPNet{IP: requestedIP, Mask: a.conf.Subnet.Mask},
Gateway: gw,
}
routes := convertRoutesToCurrent(a.conf.Routes)
return ipConfig, routes, nil
}
return nil, nil, fmt.Errorf("requested IP address %q is not available in network: %s", requestedIP, a.conf.Name)
}
startIP, endIP := a.getSearchRange()
for cur := startIP; ; cur = a.nextIP(cur) {
// don't allocate gateway IP
if gw != nil && cur.Equal(gw) {
continue
}
reserved, err := a.store.Reserve(id, cur)
if err != nil {
return nil, nil, err
}
if reserved {
ipConfig := ¤t.IPConfig{
Version: "4",
Address: net.IPNet{IP: cur, Mask: a.conf.Subnet.Mask},
Gateway: gw,
}
routes := convertRoutesToCurrent(a.conf.Routes)
return ipConfig, routes, nil
}
// break here to complete the loop
if cur.Equal(endIP) {
break
}
}
return nil, nil, fmt.Errorf("no IP addresses available in network: %s", a.conf.Name)
}
// Releases all IPs allocated for the container with given ID
func (a *IPAllocator) Release(id string) error {
a.store.Lock()
defer a.store.Unlock()
return a.store.ReleaseByID(id)
}
// Return the start and end IP addresses of a given subnet, excluding
// the broadcast address (eg, 192.168.1.255)
func networkRange(ipnet *net.IPNet) (net.IP, net.IP, error) {
if ipnet.IP == nil {
return nil, nil, fmt.Errorf("missing field %q in IPAM configuration", "subnet")
}
ip, err := canonicalizeIP(ipnet.IP)
if err != nil {
return nil, nil, fmt.Errorf("IP not v4 nor v6")
}
if len(ip) != len(ipnet.Mask) {
return nil, nil, fmt.Errorf("IPNet IP and Mask version mismatch")
}
var end net.IP
for i := 0; i < len(ip); i++ {
end = append(end, ip[i]|^ipnet.Mask[i])
}
// Exclude the broadcast address for IPv4
if ip.To4() != nil {
end[3]--
}
return ipnet.IP, end, nil
}
// nextIP returns the next ip of curIP within ipallocator's subnet
func (a *IPAllocator) nextIP(curIP net.IP) net.IP {
if curIP.Equal(a.end) {
return a.start
}
return ip.NextIP(curIP)
}
// getSearchRange returns the start and end ip based on the last reserved ip
func (a *IPAllocator) getSearchRange() (net.IP, net.IP) {
var startIP net.IP
var endIP net.IP
startFromLastReservedIP := false
lastReservedIP, err := a.store.LastReservedIP()
if err != nil && !os.IsNotExist(err) {
log.Printf("Error retriving last reserved ip: %v", err)
} else if lastReservedIP != nil {
subnet := net.IPNet{
IP: a.conf.Subnet.IP,
Mask: a.conf.Subnet.Mask,
}
err := validateRangeIP(lastReservedIP, &subnet, a.start, a.end)
if err == nil {
startFromLastReservedIP = true
}
}
if startFromLastReservedIP {
startIP = a.nextIP(lastReservedIP)
endIP = lastReservedIP
} else {
startIP = a.start
endIP = a.end
}
return startIP, endIP
}