mirror of
https://github.com/xjasonlyu/tun2socks.git
synced 2025-10-06 01:07:03 +08:00
117 lines
2.4 KiB
Go
117 lines
2.4 KiB
Go
//go:build linux
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package tun
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import (
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"fmt"
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"unsafe"
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"github.com/xjasonlyu/tun2socks/v2/core/device"
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"golang.org/x/sys/unix"
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"gvisor.dev/gvisor/pkg/tcpip/link/fdbased"
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"gvisor.dev/gvisor/pkg/tcpip/link/rawfile"
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"gvisor.dev/gvisor/pkg/tcpip/link/tun"
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"gvisor.dev/gvisor/pkg/tcpip/stack"
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)
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type TUN struct {
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stack.LinkEndpoint
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fd int
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mtu uint32
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name string
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}
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func Open(name string, mtu uint32) (device.Device, error) {
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t := &TUN{name: name, mtu: mtu}
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if len(t.name) >= unix.IFNAMSIZ {
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return nil, fmt.Errorf("interface name too long: %s", t.name)
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}
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fd, err := tun.Open(t.name)
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if err != nil {
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return nil, fmt.Errorf("create tun: %w", err)
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}
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t.fd = fd
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if t.mtu > 0 {
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if err := setMTU(t.name, t.mtu); err != nil {
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return nil, fmt.Errorf("set mtu: %w", err)
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}
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}
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_mtu, err := rawfile.GetMTU(t.name)
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if err != nil {
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return nil, fmt.Errorf("get mtu: %w", err)
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}
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t.mtu = _mtu
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ep, err := fdbased.New(&fdbased.Options{
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FDs: []int{fd},
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MTU: t.mtu,
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// TUN only, ignore ethernet header.
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EthernetHeader: false,
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// SYS_READV support only for TUN fd.
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PacketDispatchMode: fdbased.Readv,
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// TAP/TUN fd's are not sockets and using the WritePackets calls results
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// in errors as it always defaults to using SendMMsg which is not supported
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// for tap/tun device fds.
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//
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// This CL changes WritePackets to gracefully degrade to using writev instead
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// of sendmmsg if the underlying fd is not a socket.
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//
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// Fixed: https://github.com/google/gvisor/commit/f33d034fecd7723a1e560ccc62aeeba328454fd0
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MaxSyscallHeaderBytes: 0x00,
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})
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if err != nil {
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return nil, fmt.Errorf("create endpoint: %w", err)
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}
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t.LinkEndpoint = ep
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return t, nil
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}
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func (t *TUN) Name() string {
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return t.name
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}
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func (t *TUN) Close() error {
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return unix.Close(t.fd)
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}
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// Ref: wireguard tun/tun_linux.go setMTU.
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func setMTU(name string, n uint32) error {
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// open datagram socket
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fd, err := unix.Socket(
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unix.AF_INET,
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unix.SOCK_DGRAM,
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0,
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)
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if err != nil {
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return err
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}
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defer unix.Close(fd)
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const ifReqSize = unix.IFNAMSIZ + 64
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// do ioctl call
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var ifr [ifReqSize]byte
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copy(ifr[:], name)
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*(*uint32)(unsafe.Pointer(&ifr[unix.IFNAMSIZ])) = n
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_, _, errno := unix.Syscall(
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unix.SYS_IOCTL,
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uintptr(fd),
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uintptr(unix.SIOCSIFMTU),
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uintptr(unsafe.Pointer(&ifr[0])),
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)
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if errno != 0 {
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return fmt.Errorf("failed to set MTU: %w", errno)
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}
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return nil
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}
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