mirror of https://github.com/tailscale/tailscale/
net/interfaces: add func LikelyHomeRouterIP
For discovering where we might direct NAT-PMP/PCP/UPnP queries at in the future.reviewable/pr527/r1
Brad Fitzpatrick
4 years ago
parent
c3c607e78a
commit
32156330a8
@ -0,0 +1,66 @@
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// 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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@ -0,0 +1,59 @@
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// 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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"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 = likelyHomeRouterIPLinux
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}
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/*
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Parse 10.0.0.1 out of:
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$ cat /proc/net/route
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Iface Destination Gateway Flags RefCnt Use Metric Mask MTU Window IRTT
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ens18 00000000 0100000A 0003 0 0 0 00000000 0 0 0
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ens18 0000000A 00000000 0001 0 0 0 0000FFFF 0 0 0
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*/
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func likelyHomeRouterIPLinux() (ret netaddr.IP, ok bool) {
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lineNum := 0
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var f []mem.RO
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lineread.File("/proc/net/route", func(line []byte) error {
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lineNum++
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if lineNum == 1 {
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// Skip header line.
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return nil
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}
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f = mem.AppendFields(f[:0], mem.B(line))
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if len(f) < 4 {
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return nil
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}
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gwHex, flagsHex := f[2], f[3]
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flags, err := mem.ParseUint(flagsHex, 16, 16)
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if err != nil {
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return nil // ignore error, skip line and keep going
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}
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const RTF_UP = 0x0001
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const RTF_GATEWAY = 0x0002
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if flags&(RTF_UP|RTF_GATEWAY) != RTF_UP|RTF_GATEWAY {
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return nil
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}
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ipu32, err := mem.ParseUint(gwHex, 16, 32)
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if err != nil {
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return nil // ignore error, skip line and keep going
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}
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ip := netaddr.IPv4(byte(ipu32), byte(ipu32>>8), byte(ipu32>>16), byte(ipu32>>24))
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if 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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@ -0,0 +1,71 @@
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// 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 = likelyHomeRouterIPWindows
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}
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/*
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Parse out 10.0.0.1 from:
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Z:\>route print -4
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===========================================================================
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Interface List
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15...aa 15 48 ff 1c 72 ......Red Hat VirtIO Ethernet Adapter
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5...........................Tailscale Tunnel
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1...........................Software Loopback Interface 1
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===========================================================================
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IPv4 Route Table
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===========================================================================
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Active Routes:
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Network Destination Netmask Gateway Interface Metric
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0.0.0.0 0.0.0.0 10.0.0.1 10.0.28.63 5
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10.0.0.0 255.255.0.0 On-link 10.0.28.63 261
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10.0.28.63 255.255.255.255 On-link 10.0.28.63 261
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10.0.42.0 255.255.255.0 100.103.42.106 100.103.42.106 5
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10.0.255.255 255.255.255.255 On-link 10.0.28.63 261
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34.193.248.174 255.255.255.255 100.103.42.106 100.103.42.106 5
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*/
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func likelyHomeRouterIPWindows() (ret netaddr.IP, ok bool) {
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cmd := exec.Command("route", "print", "-4")
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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("0.0.0.0")) {
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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("0.0.0.0") || !f[1].EqualString("0.0.0.0") {
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return nil
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}
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ipm := f[2]
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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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