52 lines
1.2 KiB
Go
52 lines
1.2 KiB
Go
// Copyright 2016 The Netstack Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package tun contains methods to open TAP and TUN devices.
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package tun
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import (
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"syscall"
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"unsafe"
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)
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// Open opens the specified TUN device, sets it to non-blocking mode, and
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// returns its file descriptor.
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func Open(name string) (int, error) {
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return open(name, syscall.IFF_TUN|syscall.IFF_NO_PI)
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}
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// OpenTAP opens the specified TAP device, sets it to non-blocking mode, and
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// returns its file descriptor.
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func OpenTAP(name string) (int, error) {
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return open(name, syscall.IFF_TAP|syscall.IFF_NO_PI)
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}
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func open(name string, flags uint16) (int, error) {
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fd, err := syscall.Open("/dev/net/tun", syscall.O_RDWR, 0)
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if err != nil {
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return -1, err
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}
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var ifr struct {
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name [16]byte
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flags uint16
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_ [22]byte
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}
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copy(ifr.name[:], name)
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ifr.flags = flags
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_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, uintptr(fd), syscall.TUNSETIFF, uintptr(unsafe.Pointer(&ifr)))
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if errno != 0 {
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syscall.Close(fd)
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return -1, errno
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}
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if err = syscall.SetNonblock(fd, true); err != nil {
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syscall.Close(fd)
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return -1, err
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}
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return fd, nil
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}
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