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tailscale/interfaces/interfaces.go

95 lines
2.2 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 contains helpers for looking up system network interfaces.
package interfaces
import (
"net"
"strings"
)
// Tailscale returns the current machine's Tailscale interface, if any.
// If none is found, all zero values are returned.
// A non-nil error is only returned on a problem listing the system interfaces.
func Tailscale() (net.IP, *net.Interface, error) {
ifs, err := net.Interfaces()
if err != nil {
return nil, nil, err
}
for _, iface := range ifs {
if !maybeTailscaleInterfaceName(iface.Name) {
continue
}
addrs, err := iface.Addrs()
if err != nil {
continue
}
for _, a := range addrs {
if ipnet, ok := a.(*net.IPNet); ok && IsTailscaleIP(ipnet.IP) {
return ipnet.IP, &iface, nil
}
}
}
return nil, nil, nil
}
// HaveIPv6GlobalAddress reports whether the machine appears to have a
// global scope unicast IPv6 address.
//
// It only returns an error if there's a problem querying the system
// interfaces.
func HaveIPv6GlobalAddress() (bool, error) {
ifs, err := net.Interfaces()
if err != nil {
return false, err
}
for _, iface := range ifs {
if isLoopbackInterfaceName(iface.Name) {
continue
}
addrs, err := iface.Addrs()
if err != nil {
continue
}
for _, a := range addrs {
ipnet, ok := a.(*net.IPNet)
if !ok {
continue
}
if ipnet.IP.To4() != nil || !ipnet.IP.IsGlobalUnicast() {
continue
}
return true, nil
}
}
return false, nil
}
func isLoopbackInterfaceName(s string) bool {
return strings.HasPrefix(s, "lo")
}
// maybeTailscaleInterfaceName reports whether s is an interface
// name that might be used by Tailscale.
func maybeTailscaleInterfaceName(s string) bool {
return strings.HasPrefix(s, "wg") ||
strings.HasPrefix(s, "ts") ||
strings.HasPrefix(s, "tailscale")
}
// IsTailscaleIP reports whether ip is an IP in a range used by
// Tailscale virtual network interfaces.
func IsTailscaleIP(ip net.IP) bool {
return cgNAT.Contains(ip)
}
var cgNAT = func() *net.IPNet {
_, ipNet, err := net.ParseCIDR("100.64.0.0/10")
if err != nil {
panic(err)
}
return ipNet
}()