94 lines
2.3 KiB
Go
94 lines
2.3 KiB
Go
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// +build linux
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/*
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Copyright 2017 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package iptables
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import (
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"fmt"
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"net"
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"os"
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"time"
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"golang.org/x/sys/unix"
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"k8s.io/apimachinery/pkg/util/wait"
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)
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type locker struct {
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lock16 *os.File
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lock14 *net.UnixListener
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}
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func (l *locker) Close() {
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if l.lock16 != nil {
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l.lock16.Close()
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}
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if l.lock14 != nil {
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l.lock14.Close()
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}
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}
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func grabIptablesLocks(lockfilePath string) (iptablesLocker, error) {
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var err error
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var success bool
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l := &locker{}
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defer func(l *locker) {
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// Clean up immediately on failure
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if !success {
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l.Close()
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}
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}(l)
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// Grab both 1.6.x and 1.4.x-style locks; we don't know what the
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// iptables-restore version is if it doesn't support --wait, so we
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// can't assume which lock method it'll use.
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// Roughly duplicate iptables 1.6.x xtables_lock() function.
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l.lock16, err = os.OpenFile(lockfilePath, os.O_CREATE, 0600)
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if err != nil {
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return nil, fmt.Errorf("failed to open iptables lock %s: %v", lockfilePath, err)
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}
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if err := wait.PollImmediate(200*time.Millisecond, 2*time.Second, func() (bool, error) {
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if err := grabIptablesFileLock(l.lock16); err != nil {
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return false, nil
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}
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return true, nil
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}); err != nil {
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return nil, fmt.Errorf("failed to acquire new iptables lock: %v", err)
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}
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// Roughly duplicate iptables 1.4.x xtables_lock() function.
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if err := wait.PollImmediate(200*time.Millisecond, 2*time.Second, func() (bool, error) {
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l.lock14, err = net.ListenUnix("unix", &net.UnixAddr{Name: "@xtables", Net: "unix"})
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if err != nil {
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return false, nil
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}
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return true, nil
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}); err != nil {
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return nil, fmt.Errorf("failed to acquire old iptables lock: %v", err)
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}
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success = true
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return l, nil
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}
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func grabIptablesFileLock(f *os.File) error {
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return unix.Flock(int(f.Fd()), unix.LOCK_EX|unix.LOCK_NB)
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}
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