mirror of
https://github.com/k3s-io/k3s.git
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66 lines
1.6 KiB
Go
66 lines
1.6 KiB
Go
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// Copyright 2015 flannel authors
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//
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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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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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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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// +build !windows
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package ip
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import (
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"bytes"
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"fmt"
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"os"
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"syscall"
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"unsafe"
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)
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const (
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tunDevice = "/dev/net/tun"
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ifnameSize = 16
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)
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type ifreqFlags struct {
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IfrnName [ifnameSize]byte
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IfruFlags uint16
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}
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func ioctl(fd int, request, argp uintptr) error {
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_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, uintptr(fd), request, argp)
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if errno != 0 {
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return fmt.Errorf("ioctl failed with '%s'", errno)
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}
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return nil
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}
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func fromZeroTerm(s []byte) string {
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return string(bytes.TrimRight(s, "\000"))
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}
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func OpenTun(name string) (*os.File, string, error) {
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tun, err := os.OpenFile(tunDevice, os.O_RDWR, 0)
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if err != nil {
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return nil, "", err
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}
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var ifr ifreqFlags
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copy(ifr.IfrnName[:len(ifr.IfrnName)-1], []byte(name+"\000"))
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ifr.IfruFlags = syscall.IFF_TUN | syscall.IFF_NO_PI
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err = ioctl(int(tun.Fd()), syscall.TUNSETIFF, uintptr(unsafe.Pointer(&ifr)))
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if err != nil {
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return nil, "", err
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}
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ifname := fromZeroTerm(ifr.IfrnName[:ifnameSize])
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return tun, ifname, nil
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}
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