github.com/coreos/rocket@v1.30.1-0.20200224141603-171c416fac02/networking/tuntap/tuntap.go (about) 1 // Copyright 2015 The rkt Authors 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 package tuntap 16 17 import ( 18 "bytes" 19 "errors" 20 "fmt" 21 "os" 22 "syscall" 23 "unsafe" 24 25 "github.com/hashicorp/errwrap" 26 ) 27 28 const ( 29 Tun = 0x1 30 Tap = 0x2 31 32 NoPi = 0x1000 33 OneQueue = 0x2000 34 VnetHdr = 0x4000 35 TunExcl = 0x8000 36 ) 37 38 type ifReq struct { 39 Name [0x10]byte 40 Flags uint16 41 pad [0x28 - 0x12]byte 42 } 43 44 type Interface struct { 45 name string 46 file *os.File 47 } 48 49 func Open(ifName string, kind uint16) (*Interface, error) { 50 if ifName == "" { 51 ifName = "tap%d" 52 } 53 file, err := os.OpenFile("/dev/net/tun", os.O_RDWR, 0) 54 if err != nil { 55 return nil, err 56 } 57 58 var req ifReq 59 copy(req.Name[:15], ifName) 60 req.Flags = kind | NoPi | VnetHdr 61 62 _, _, errno := syscall.Syscall(syscall.SYS_IOCTL, file.Fd(), uintptr(syscall.TUNSETIFF), uintptr(unsafe.Pointer(&req))) 63 if errno != 0 { 64 file.Close() 65 return nil, fmt.Errorf("ioctl failed (TUNSETIFF): %v", errno) 66 } 67 68 return &Interface{ 69 name: string(req.Name[:bytes.IndexByte(req.Name[:], 0)]), 70 file: file, 71 }, nil 72 } 73 74 func (iface *Interface) Close() error { 75 return iface.file.Close() 76 } 77 78 func operateOnIface(name string, kind uint16, persistency uintptr) (string, error) { 79 iface, err := Open(name, kind) 80 if err != nil { 81 return "", err 82 } 83 84 _, _, errno := syscall.Syscall(syscall.SYS_IOCTL, iface.file.Fd(), uintptr(syscall.TUNSETPERSIST), persistency) 85 err = iface.Close() 86 if err != nil { 87 return "", errwrap.Wrap(errors.New("iface close error "), err) 88 } 89 90 if errno != 0 { 91 return "", fmt.Errorf("ioctl failed (TUNSETPERSIST): %v", errno) 92 } 93 94 return iface.name, nil 95 } 96 97 func CreatePersistentIface(nameTemplate string, kind uint16) (string, error) { 98 return operateOnIface(nameTemplate, kind, 1) 99 } 100 101 func RemovePersistentIface(name string, kind uint16) error { 102 _, err := operateOnIface(name, kind, 0) 103 return err 104 }