mirror of
https://github.com/tailscale/tailscale.git
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67 lines
1.5 KiB
Go
67 lines
1.5 KiB
Go
// Copyright (c) 2020 Tailscale Inc & 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 interfaces
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import (
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"os/exec"
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"go4.org/mem"
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"inet.af/netaddr"
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"tailscale.com/util/lineread"
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)
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func init() {
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likelyHomeRouterIP = likelyHomeRouterIPDarwin
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}
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/*
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Parse out 10.0.0.1 from:
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$ netstat -r -n -f inet
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Routing tables
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Internet:
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Destination Gateway Flags Netif Expire
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default 10.0.0.1 UGSc en0
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default link#14 UCSI utun2
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10/16 link#4 UCS en0 !
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10.0.0.1/32 link#4 UCS en0 !
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...
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*/
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func likelyHomeRouterIPDarwin() (ret netaddr.IP, ok bool) {
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cmd := exec.Command("/usr/sbin/netstat", "-r", "-n", "-f", "inet")
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stdout, err := cmd.StdoutPipe()
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if err != nil {
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return
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}
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if err := cmd.Start(); err != nil {
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return
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}
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defer cmd.Wait()
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var f []mem.RO
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lineread.Reader(stdout, func(lineb []byte) error {
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line := mem.B(lineb)
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if !mem.Contains(line, mem.S("default")) {
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return nil
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}
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f = mem.AppendFields(f[:0], line)
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if len(f) < 3 || !f[0].EqualString("default") {
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return nil
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}
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ipm, flagsm := f[1], f[2]
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if !mem.Contains(flagsm, mem.S("G")) {
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return nil
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}
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ip, err := netaddr.ParseIP(string(mem.Append(nil, ipm)))
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if err == nil && isPrivateIP(ip) {
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ret = ip
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}
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return nil
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})
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return ret, !ret.IsZero()
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}
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