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backend.go
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backend.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 disk
import (
"io/ioutil"
"net"
"os"
"path/filepath"
"runtime"
"strings"
"github.com/containernetworking/plugins/plugins/ipam/host-local/backend"
)
const lastIPFilePrefix = "last_reserved_ip."
const LineBreak = "\r\n"
var defaultDataDir = "/var/lib/cni/networks"
// Store is a simple disk-backed store that creates one file per IP
// address in a given directory. The contents of the file are the container ID.
type Store struct {
*FileLock
dataDir string
}
// Store implements the Store interface
var _ backend.Store = &Store{}
func New(network, dataDir string) (*Store, error) {
if dataDir == "" {
dataDir = defaultDataDir
}
dir := filepath.Join(dataDir, network)
if err := os.MkdirAll(dir, 0755); err != nil {
return nil, err
}
lk, err := NewFileLock(dir)
if err != nil {
return nil, err
}
return &Store{lk, dir}, nil
}
func (s *Store) Reserve(id string, ifname string, ip net.IP, rangeID string) (bool, error) {
fname := GetEscapedPath(s.dataDir, ip.String())
f, err := os.OpenFile(fname, os.O_RDWR|os.O_EXCL|os.O_CREATE, 0644)
if os.IsExist(err) {
return false, nil
}
if err != nil {
return false, err
}
if _, err := f.WriteString(strings.TrimSpace(id) + LineBreak + ifname); err != nil {
f.Close()
os.Remove(f.Name())
return false, err
}
if err := f.Close(); err != nil {
os.Remove(f.Name())
return false, err
}
// store the reserved ip in lastIPFile
ipfile := GetEscapedPath(s.dataDir, lastIPFilePrefix+rangeID)
err = ioutil.WriteFile(ipfile, []byte(ip.String()), 0644)
if err != nil {
return false, err
}
return true, nil
}
// LastReservedIP returns the last reserved IP if exists
func (s *Store) LastReservedIP(rangeID string) (net.IP, error) {
ipfile := GetEscapedPath(s.dataDir, lastIPFilePrefix+rangeID)
data, err := ioutil.ReadFile(ipfile)
if err != nil {
return nil, err
}
return net.ParseIP(string(data)), nil
}
func (s *Store) FindByKey(id string, ifname string, match string) (bool, error) {
found := false
err := filepath.Walk(s.dataDir, func(path string, info os.FileInfo, err error) error {
if err != nil || info.IsDir() {
return nil
}
data, err := ioutil.ReadFile(path)
if err != nil {
return nil
}
if strings.TrimSpace(string(data)) == match {
found = true
}
return nil
})
return found, err
}
func (s *Store) FindByID(id string, ifname string) bool {
s.Lock()
defer s.Unlock()
found := false
match := strings.TrimSpace(id) + LineBreak + ifname
found, err := s.FindByKey(id, ifname, match)
// Match anything created by this id
if !found && err == nil {
match := strings.TrimSpace(id)
found, err = s.FindByKey(id, ifname, match)
}
return found
}
func (s *Store) ReleaseByKey(id string, ifname string, match string) (bool, error) {
found := false
err := filepath.Walk(s.dataDir, func(path string, info os.FileInfo, err error) error {
if err != nil || info.IsDir() {
return nil
}
data, err := ioutil.ReadFile(path)
if err != nil {
return nil
}
if strings.TrimSpace(string(data)) == match {
if err := os.Remove(path); err != nil {
return nil
}
found = true
}
return nil
})
return found, err
}
// N.B. This function eats errors to be tolerant and
// release as much as possible
func (s *Store) ReleaseByID(id string, ifname string) error {
found := false
match := strings.TrimSpace(id) + LineBreak + ifname
found, err := s.ReleaseByKey(id, ifname, match)
// For backwards compatibility, look for files written by a previous version
if !found && err == nil {
match := strings.TrimSpace(id)
found, err = s.ReleaseByKey(id, ifname, match)
}
return err
}
// GetByID returns the IPs which have been allocated to the specific ID
func (s *Store) GetByID(id string, ifname string) []net.IP {
var ips []net.IP
match := strings.TrimSpace(id) + LineBreak + ifname
// matchOld for backwards compatibility
matchOld := strings.TrimSpace(id)
// walk through all ips in this network to get the ones which belong to a specific ID
_ = filepath.Walk(s.dataDir, func(path string, info os.FileInfo, err error) error {
if err != nil || info.IsDir() {
return nil
}
data, err := ioutil.ReadFile(path)
if err != nil {
return nil
}
if strings.TrimSpace(string(data)) == match || strings.TrimSpace(string(data)) == matchOld {
_, ipString := filepath.Split(path)
if ip := net.ParseIP(ipString); ip != nil {
ips = append(ips, ip)
}
}
return nil
})
return ips
}
func GetEscapedPath(dataDir string, fname string) string {
if runtime.GOOS == "windows" {
fname = strings.Replace(fname, ":", "_", -1)
}
return filepath.Join(dataDir, fname)
}