| // Copyright 2018 Google Inc. |
| // |
| // 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. |
| |
| // +build linux |
| |
| // Package tun contains methods to open TAP and TUN devices. |
| package tun |
| |
| import ( |
| "syscall" |
| "unsafe" |
| ) |
| |
| // Open opens the specified TUN device, sets it to non-blocking mode, and |
| // returns its file descriptor. |
| func Open(name string) (int, error) { |
| return open(name, syscall.IFF_TUN|syscall.IFF_NO_PI) |
| } |
| |
| // OpenTAP opens the specified TAP device, sets it to non-blocking mode, and |
| // returns its file descriptor. |
| func OpenTAP(name string) (int, error) { |
| return open(name, syscall.IFF_TAP|syscall.IFF_NO_PI) |
| } |
| |
| func open(name string, flags uint16) (int, error) { |
| fd, err := syscall.Open("/dev/net/tun", syscall.O_RDWR, 0) |
| if err != nil { |
| return -1, err |
| } |
| |
| var ifr struct { |
| name [16]byte |
| flags uint16 |
| _ [22]byte |
| } |
| |
| copy(ifr.name[:], name) |
| ifr.flags = flags |
| _, _, errno := syscall.Syscall(syscall.SYS_IOCTL, uintptr(fd), syscall.TUNSETIFF, uintptr(unsafe.Pointer(&ifr))) |
| if errno != 0 { |
| syscall.Close(fd) |
| return -1, errno |
| } |
| |
| if err = syscall.SetNonblock(fd, true); err != nil { |
| syscall.Close(fd) |
| return -1, err |
| } |
| |
| return fd, nil |
| } |