337 lines
8.6 KiB
Go
337 lines
8.6 KiB
Go
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/* SPDX-License-Identifier: MIT
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*
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* Copyright (C) 2017-2023 WireGuard LLC. All Rights Reserved.
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*/
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package tun
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import (
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"crypto/md5"
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"errors"
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"fmt"
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"net/netip"
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"os"
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"sync"
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"sync/atomic"
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"time"
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"unsafe"
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_ "unsafe"
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"golang.org/x/sys/windows"
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"golang.zx2c4.com/wintun"
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"golang.zx2c4.com/wireguard/windows/tunnel/winipcfg"
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)
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const (
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rateMeasurementGranularity = uint64((time.Second / 2) / time.Nanosecond)
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spinloopRateThreshold = 800000000 / 8 // 800mbps
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spinloopDuration = uint64(time.Millisecond / 80 / time.Nanosecond) // ~1gbit/s
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)
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type rateJuggler struct {
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current atomic.Uint64
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nextByteCount atomic.Uint64
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nextStartTime atomic.Int64
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changing atomic.Bool
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}
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type NativeTun struct {
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wt *wintun.Adapter
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name string
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handle windows.Handle
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rate rateJuggler
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session wintun.Session
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readWait windows.Handle
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events chan Event
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running sync.WaitGroup
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closeOnce sync.Once
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close atomic.Bool
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mtu int
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}
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var (
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WintunTunnelType = "vxlan"
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WintunGUIDPrefix = "virtual-vxlan Windows GUID v1"
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)
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//go:linkname procyield runtime.procyield
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func procyield(cycles uint32)
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//go:linkname nanotime runtime.nanotime
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func nanotime() int64
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// Create an 128bit GUID using interface name.
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func generateGUIDByDeviceName(name string) (*windows.GUID, error) {
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hash := md5.New()
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_, err := hash.Write([]byte(WintunGUIDPrefix + name))
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if err != nil {
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return nil, err
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}
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sum := hash.Sum(nil)
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return (*windows.GUID)(unsafe.Pointer(&sum[0])), nil
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}
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// CreateTUN creates a Wintun interface with the given name. Should a Wintun
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// interface with the same name exist, it is reused.
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func CreateTUN(ifname string, mtu int) (Device, error) {
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guid, err := generateGUIDByDeviceName(ifname)
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if err != nil {
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return nil, err
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}
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return CreateTUNWithRequestedGUID(ifname, guid, mtu)
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}
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// CreateTUNWithRequestedGUID creates a Wintun interface with the given name and
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// a requested GUID. Should a Wintun interface with the same name exist, it is reused.
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func CreateTUNWithRequestedGUID(ifname string, requestedGUID *windows.GUID, mtu int) (Device, error) {
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wt, err := wintun.CreateAdapter(ifname, WintunTunnelType, requestedGUID)
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if err != nil {
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return nil, fmt.Errorf("error creating interface: %w", err)
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}
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forcedMTU := 1420
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if mtu > 0 {
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forcedMTU = mtu
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}
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tun := &NativeTun{
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wt: wt,
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name: ifname,
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handle: windows.InvalidHandle,
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events: make(chan Event, 10),
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mtu: forcedMTU,
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}
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err = tun.setMTU(windows.AF_INET, forcedMTU)
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if err != nil {
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wt.Close()
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close(tun.events)
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return nil, fmt.Errorf("error setting MTU for IPv4: %w", err)
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}
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err = tun.setMTU(windows.AF_INET6, forcedMTU)
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if err != nil {
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wt.Close()
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close(tun.events)
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return nil, fmt.Errorf("error setting MTU for IPv6: %w", err)
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}
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tun.session, err = wt.StartSession(0x800000) // Ring capacity, 8 MiB
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if err != nil {
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tun.wt.Close()
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close(tun.events)
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return nil, fmt.Errorf("error starting session: %w", err)
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}
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tun.readWait = tun.session.ReadWaitEvent()
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return tun, nil
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}
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func (tun *NativeTun) Name() (string, error) {
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return tun.name, nil
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}
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func (tun *NativeTun) File() *os.File {
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return nil
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}
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func (tun *NativeTun) Events() <-chan Event {
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return tun.events
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}
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func (tun *NativeTun) Close() error {
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var err error
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tun.closeOnce.Do(func() {
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tun.close.Store(true)
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windows.SetEvent(tun.readWait)
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tun.running.Wait()
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tun.session.End()
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if tun.wt != nil {
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tun.wt.Close()
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}
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close(tun.events)
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})
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return err
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}
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func (tun *NativeTun) setMTU(family winipcfg.AddressFamily, mtu int) error {
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luid := winipcfg.LUID(tun.LUID())
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ipif, err := luid.IPInterface(family)
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if err != nil {
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return err
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}
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ipif.NLMTU = uint32(mtu)
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return ipif.Set()
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}
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func (tun *NativeTun) SetMTU(mtu int) error {
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if tun.close.Load() {
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return nil
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}
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err := tun.setMTU(windows.AF_INET, mtu)
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if err != nil {
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return fmt.Errorf("error setting MTU for IPv4: %v", err)
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}
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err = tun.setMTU(windows.AF_INET6, mtu)
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if err != nil {
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return fmt.Errorf("error setting MTU for IPv6: %v", err)
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}
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update := tun.mtu != mtu
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tun.mtu = mtu
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if update {
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tun.events <- EventMTUUpdate
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}
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return nil
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}
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func (tun *NativeTun) MTU() (int, error) {
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return tun.mtu, nil
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}
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// Note: Read() and Write() assume the caller comes only from a single thread; there's no locking.
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func (tun *NativeTun) Read(b []byte) (int, error) {
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tun.running.Add(1)
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defer tun.running.Done()
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retry:
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if tun.close.Load() {
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return 0, os.ErrClosed
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}
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start := nanotime()
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shouldSpin := tun.rate.current.Load() >= spinloopRateThreshold && uint64(start-tun.rate.nextStartTime.Load()) <= rateMeasurementGranularity*2
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for {
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if tun.close.Load() {
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return 0, os.ErrClosed
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}
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packet, err := tun.session.ReceivePacket()
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switch err {
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case nil:
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n := copy(b, packet)
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tun.session.ReleaseReceivePacket(packet)
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tun.rate.update(uint64(n))
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return n, nil
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case windows.ERROR_NO_MORE_ITEMS:
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if !shouldSpin || uint64(nanotime()-start) >= spinloopDuration {
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windows.WaitForSingleObject(tun.readWait, windows.INFINITE)
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goto retry
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}
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procyield(1)
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continue
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case windows.ERROR_HANDLE_EOF:
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return 0, os.ErrClosed
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case windows.ERROR_INVALID_DATA:
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return 0, errors.New("send ring corrupt")
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}
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return 0, fmt.Errorf("Read failed: %w", err)
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}
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}
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func (tun *NativeTun) Write(b []byte) (int, error) {
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tun.running.Add(1)
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defer tun.running.Done()
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if tun.close.Load() {
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return 0, os.ErrClosed
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}
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packetSize := len(b)
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tun.rate.update(uint64(packetSize))
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packet, err := tun.session.AllocateSendPacket(packetSize)
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switch err {
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case nil:
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// TODO: Explore options to eliminate this copy.
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copy(packet, b)
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tun.session.SendPacket(packet)
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return packetSize, nil
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case windows.ERROR_HANDLE_EOF:
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return 0, os.ErrClosed
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case windows.ERROR_BUFFER_OVERFLOW:
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return 0, nil // Dropping when ring is full.
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}
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return 0, fmt.Errorf("Write failed: %w", err)
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}
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// LUID returns Windows interface instance ID.
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func (tun *NativeTun) LUID() uint64 {
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tun.running.Add(1)
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defer tun.running.Done()
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if tun.close.Load() {
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return 0
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}
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return tun.wt.LUID()
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}
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func (tun *NativeTun) SetIPAddresses(addresses []netip.Prefix) error {
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luid := winipcfg.LUID(tun.LUID())
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err := luid.SetIPAddresses(addresses)
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if err != nil {
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return fmt.Errorf("failed to set address: %w", err)
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}
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return nil
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}
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func addrFromSocketAddress(sockAddr windows.SocketAddress) netip.Addr {
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ip := sockAddr.IP()
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ip4 := ip.To4()
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var addr netip.Addr
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if ip4 != nil {
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addr = netip.AddrFrom4([4]byte(ip4))
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} else {
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addr = netip.AddrFrom16([16]byte(ip))
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}
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return addr
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}
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func (tun *NativeTun) GetIPAddresses() ([]netip.Prefix, error) {
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luid := winipcfg.LUID(tun.LUID())
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ipAdaters, err := winipcfg.GetAdaptersAddresses(windows.AF_UNSPEC, winipcfg.GAAFlagIncludePrefix|winipcfg.GAAFlagSkipAnycast|winipcfg.GAAFlagSkipMulticast|winipcfg.GAAFlagSkipDNSServer|winipcfg.GAAFlagSkipFriendlyName|winipcfg.GAAFlagSkipDNSInfo)
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if err != nil {
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return nil, fmt.Errorf("failed to get IP adapters: %w", err)
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}
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var prefixes []netip.Prefix
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for _, ipAdater := range ipAdaters {
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if ipAdater.LUID == luid {
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unicast := ipAdater.FirstUnicastAddress
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for unicast != nil {
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addr := addrFromSocketAddress(unicast.Address)
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prefix := ipAdater.FirstPrefix
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for prefix != nil {
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pAddr := addrFromSocketAddress(prefix.Address)
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if (pAddr.Is4() && prefix.PrefixLength != 32) || (pAddr.Is6() && prefix.PrefixLength != 128) {
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nPrefix := netip.PrefixFrom(pAddr, int(prefix.PrefixLength))
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if nPrefix.Contains(addr) {
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prefixes = append(prefixes, netip.PrefixFrom(addr, int(prefix.PrefixLength)))
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prefix = nil
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continue
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}
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}
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prefix = prefix.Next
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}
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unicast = unicast.Next
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}
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}
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}
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return prefixes, nil
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}
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// RunningVersion returns the running version of the Wintun driver.
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func (tun *NativeTun) RunningVersion() (version uint32, err error) {
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return wintun.RunningVersion()
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}
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func (rate *rateJuggler) update(packetLen uint64) {
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now := nanotime()
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total := rate.nextByteCount.Add(packetLen)
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period := uint64(now - rate.nextStartTime.Load())
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if period >= rateMeasurementGranularity {
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if !rate.changing.CompareAndSwap(false, true) {
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return
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}
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rate.nextStartTime.Store(now)
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rate.current.Store(total * uint64(time.Second/time.Nanosecond) / period)
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rate.nextByteCount.Store(0)
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rate.changing.Store(false)
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}
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}
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