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tailscale/net/interfaces/interfaces_windows.go

197 lines
5.3 KiB
Go

// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package interfaces
import (
"fmt"
"log"
"net/url"
"os/exec"
"syscall"
"unsafe"
"go4.org/mem"
"golang.org/x/sys/windows"
"golang.zx2c4.com/wireguard/windows/tunnel/winipcfg"
"inet.af/netaddr"
"tailscale.com/tsconst"
"tailscale.com/util/lineread"
)
func init() {
likelyHomeRouterIP = likelyHomeRouterIPWindows
getPAC = getPACWindows
}
/*
Parse out 10.0.0.1 from:
Z:\>route print -4
===========================================================================
Interface List
15...aa 15 48 ff 1c 72 ......Red Hat VirtIO Ethernet Adapter
5...........................Tailscale Tunnel
1...........................Software Loopback Interface 1
===========================================================================
IPv4 Route Table
===========================================================================
Active Routes:
Network Destination Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 10.0.0.1 10.0.28.63 5
10.0.0.0 255.255.0.0 On-link 10.0.28.63 261
10.0.28.63 255.255.255.255 On-link 10.0.28.63 261
10.0.42.0 255.255.255.0 100.103.42.106 100.103.42.106 5
10.0.255.255 255.255.255.255 On-link 10.0.28.63 261
34.193.248.174 255.255.255.255 100.103.42.106 100.103.42.106 5
*/
func likelyHomeRouterIPWindows() (ret netaddr.IP, ok bool) {
cmd := exec.Command("route", "print", "-4")
cmd.SysProcAttr = &syscall.SysProcAttr{HideWindow: true}
stdout, err := cmd.StdoutPipe()
if err != nil {
return
}
if err := cmd.Start(); err != nil {
return
}
defer cmd.Wait()
var f []mem.RO
lineread.Reader(stdout, func(lineb []byte) error {
line := mem.B(lineb)
if !mem.Contains(line, mem.S("0.0.0.0")) {
return nil
}
f = mem.AppendFields(f[:0], line)
if len(f) < 3 || !f[0].EqualString("0.0.0.0") || !f[1].EqualString("0.0.0.0") {
return nil
}
ipm := f[2]
ip, err := netaddr.ParseIP(string(mem.Append(nil, ipm)))
if err == nil && isPrivateIP(ip) {
ret = ip
}
return nil
})
return ret, !ret.IsZero()
}
// NonTailscaleMTUs returns a map of interface LUID to interface MTU,
// for all interfaces except Tailscale tunnels.
func NonTailscaleMTUs() (map[winipcfg.LUID]uint32, error) {
mtus := map[winipcfg.LUID]uint32{}
ifs, err := NonTailscaleInterfaces()
for luid, iface := range ifs {
mtus[luid] = iface.MTU
}
return mtus, err
}
// NonTailscaleInterfaces returns a map of interface LUID to interface
// for all interfaces except Tailscale tunnels.
func NonTailscaleInterfaces() (map[winipcfg.LUID]*winipcfg.IPAdapterAddresses, error) {
ifs, err := winipcfg.GetAdaptersAddresses(windows.AF_UNSPEC, winipcfg.GAAFlagIncludeAllInterfaces)
if err != nil {
return nil, err
}
ret := map[winipcfg.LUID]*winipcfg.IPAdapterAddresses{}
for _, iface := range ifs {
if iface.Description() == tsconst.WintunInterfaceDesc {
continue
}
ret[iface.LUID] = iface
}
return ret, nil
}
// GetWindowsDefault returns the interface that has the non-Tailscale
// default route for the given address family.
//
// It returns (nil, nil) if no interface is found.
func GetWindowsDefault(family winipcfg.AddressFamily) (*winipcfg.IPAdapterAddresses, error) {
ifs, err := NonTailscaleInterfaces()
if err != nil {
return nil, err
}
routes, err := winipcfg.GetIPForwardTable2(family)
if err != nil {
return nil, err
}
bestMetric := ^uint32(0)
var bestIface *winipcfg.IPAdapterAddresses
for _, route := range routes {
iface := ifs[route.InterfaceLUID]
if route.DestinationPrefix.PrefixLength != 0 || iface == nil {
continue
}
if iface.OperStatus == winipcfg.IfOperStatusUp && route.Metric < bestMetric {
bestMetric = route.Metric
bestIface = iface
}
}
return bestIface, nil
}
func DefaultRouteInterface() (string, error) {
iface, err := GetWindowsDefault(windows.AF_INET)
if err != nil {
return "", err
}
if iface == nil {
return "(none)", nil
}
return fmt.Sprintf("%s (%s)", iface.FriendlyName(), iface.Description()), nil
}
var (
winHTTP = windows.NewLazySystemDLL("winhttp.dll")
detectAutoProxyConfigURL = winHTTP.NewProc("WinHttpDetectAutoProxyConfigUrl")
kernel32 = windows.NewLazySystemDLL("kernel32.dll")
globalFree = kernel32.NewProc("GlobalFree")
)
const (
winHTTP_AUTO_DETECT_TYPE_DHCP = 0x00000001
winHTTP_AUTO_DETECT_TYPE_DNS_A = 0x00000002
)
func getPACWindows() string {
var res *uint16
r, _, e := detectAutoProxyConfigURL.Call(
winHTTP_AUTO_DETECT_TYPE_DHCP|winHTTP_AUTO_DETECT_TYPE_DNS_A,
uintptr(unsafe.Pointer(&res)),
)
if r == 1 {
if res == nil {
log.Printf("getPACWindows: unexpected success with nil result")
return ""
}
defer globalFree.Call(uintptr(unsafe.Pointer(res)))
s := windows.UTF16PtrToString(res)
if _, err := url.Parse(s); err != nil {
log.Printf("getPACWindows: invalid URL %q from winhttp; ignoring", s)
return ""
}
return s
}
const (
ERROR_WINHTTP_AUTODETECTION_FAILED = 12180
)
if e == syscall.Errno(ERROR_WINHTTP_AUTODETECTION_FAILED) {
// Common case on networks without advertised PAC.
return ""
}
log.Printf("getPACWindows: %T=%v", e, e) // syscall.Errno=0x....
return ""
}