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netcheck, tailcfg, interfaces, magicsock: survey UPnP, NAT-PMP, PCP

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Don't do anything with UPnP, NAT-PMP, PCP yet, but see how common they
are in the wild.

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This commit is contained in:
Brad Fitzpatrick 2020-07-06 13:51:17 -07:00 committed by Brad Fitzpatrick
parent 6196b7e658
commit 5c6d8e3053
8 changed files with 265 additions and 26 deletions
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24
cmd/tailscale/netcheck.go
View File

@ -18,7 +18,6 @@
"github.com/peterbourgon/ff/v2/ffcli"
"tailscale.com/derp/derpmap"
"tailscale.com/net/dnscache"
"tailscale.com/net/interfaces"
"tailscale.com/net/netcheck"
"tailscale.com/tailcfg"
"tailscale.com/types/logger"
@ -51,11 +50,6 @@ func runNetcheck(ctx context.Context, args []string) error {
if netcheckArgs.verbose {
c.Logf = logger.WithPrefix(log.Printf, "netcheck: ")
c.Verbose = true
if gw, ok := interfaces.LikelyHomeRouterIP(); ok {
c.Logf("likely home router: %v", gw)
} else {
c.Logf("no likely home router IP found")
}
} else {
c.Logf = logger.Discard
}
@ -123,6 +117,7 @@ func printReport(dm *tailcfg.DERPMap, report *netcheck.Report) error {
}
fmt.Printf("\t* MappingVariesByDestIP: %v\n", report.MappingVariesByDestIP)
fmt.Printf("\t* HairPinning: %v\n", report.HairPinning)
fmt.Printf("\t* PortMapping: %v\n", portMapping(report))
// When DERP latency checking failed,
// magicsock will try to pick the DERP server that
@ -148,3 +143,20 @@ func printReport(dm *tailcfg.DERPMap, report *netcheck.Report) error {
}
return nil
}
func portMapping(r *netcheck.Report) string {
if !r.AnyPortMappingChecked() {
return "not checked"
}
var got []string
if r.UPnP.EqualBool(true) {
got = append(got, "UPnP")
}
if r.PMP.EqualBool(true) {
got = append(got, "NAT-PMP")
}
if r.PCP.EqualBool(true) {
got = append(got, "PCP")
}
return strings.Join(got, ", ")
}

27
net/interfaces/interfaces.go
View File

@ -234,12 +234,32 @@ func HTTPOfListener(ln net.Listener) string {
// LikelyHomeRouterIP returns the likely IP of the residential router,
// which will always be an IPv4 private address, if found.
// In addition, it returns the IP address of the current machine on
// the LAN using that gateway.
// This is used as the destination for UPnP, NAT-PMP, PCP, etc queries.
func LikelyHomeRouterIP() (ip netaddr.IP, ok bool) {
func LikelyHomeRouterIP() (gateway, myIP netaddr.IP, ok bool) {
if likelyHomeRouterIP != nil {
return likelyHomeRouterIP()
gateway, ok = likelyHomeRouterIP()
if !ok {
return
}
}
return ip, false
if !ok {
return
}
ForeachInterfaceAddress(func(i Interface, ip netaddr.IP) {
if !i.IsUp() || ip.IsZero() || !myIP.IsZero() {
return
}
for _, prefix := range privatev4s {
if prefix.Contains(gateway) && prefix.Contains(ip) {
myIP = ip
ok = true
return
}
}
})
return gateway, myIP, !myIP.IsZero()
}
func isPrivateIP(ip netaddr.IP) bool {
@ -262,6 +282,7 @@ func mustCIDR(s string) netaddr.IPPrefix {
private1 = mustCIDR("10.0.0.0/8")
private2 = mustCIDR("172.16.0.0/12")
private3 = mustCIDR("192.168.0.0/16")
privatev4s = []netaddr.IPPrefix{private1, private2, private3}
cgNAT = mustCIDR("100.64.0.0/10")
linkLocalIPv4 = mustCIDR("169.254.0.0/16")
v6Global1 = mustCIDR("2000::/3")

8
net/interfaces/interfaces_test.go
View File

@ -49,6 +49,10 @@ func TestGetState(t *testing.T) {
}
func TestLikelyHomeRouterIP(t *testing.T) {
ip, ok := LikelyHomeRouterIP()
t.Logf("got %v, %v", ip, ok)
gw, my, ok := LikelyHomeRouterIP()
if !ok {
t.Logf("no result")
return
}
t.Logf("myIP = %v; gw = %v", my, gw)
}

153
net/netcheck/netcheck.go
View File

@ -8,7 +8,9 @@
import (
"bufio"
"context"
"crypto/rand"
"crypto/tls"
"encoding/binary"
"errors"
"fmt"
"io"
@ -21,6 +23,7 @@
"time"
"github.com/tcnksm/go-httpstat"
"go4.org/mem"
"inet.af/netaddr"
"tailscale.com/derp/derphttp"
"tailscale.com/net/dnscache"
@ -34,15 +37,26 @@
)
type Report struct {
UDP bool // UDP works
IPv6 bool // IPv6 works
IPv4 bool // IPv4 works
MappingVariesByDestIP opt.Bool // for IPv4
HairPinning opt.Bool // for IPv4
PreferredDERP int // or 0 for unknown
RegionLatency map[int]time.Duration // keyed by DERP Region ID
RegionV4Latency map[int]time.Duration // keyed by DERP Region ID
RegionV6Latency map[int]time.Duration // keyed by DERP Region ID
UDP bool // UDP works
IPv6 bool // IPv6 works
IPv4 bool // IPv4 works
MappingVariesByDestIP opt.Bool // for IPv4
HairPinning opt.Bool // for IPv4
// UPnP is whether UPnP appears present on the LAN.
// Empty means not checked.
UPnP opt.Bool
// PMP is whether NAT-PMP appears present on the LAN.
// Empty means not checked.
PMP opt.Bool
// PCP is whether PCP appears present on the LAN.
// Empty means not checked.
PCP opt.Bool
PreferredDERP int // or 0 for unknown
RegionLatency map[int]time.Duration // keyed by DERP Region ID
RegionV4Latency map[int]time.Duration // keyed by DERP Region ID
RegionV6Latency map[int]time.Duration // keyed by DERP Region ID
GlobalV4 string // ip:port of global IPv4
GlobalV6 string // [ip]:port of global IPv6
@ -50,6 +64,11 @@ type Report struct {
// TODO: update Clone when adding new fields
}
// AnyPortMappingChecked reports whether any of UPnP, PMP, or PCP are non-empty.
func (r *Report) AnyPortMappingChecked() bool {
return r.UPnP != "" || r.PMP != "" || r.PCP != ""
}
func (r *Report) Clone() *Report {
if r == nil {
return nil
@ -434,6 +453,7 @@ type reportState struct {
pc4Hair net.PacketConn
incremental bool // doing a lite, follow-up netcheck
stopProbeCh chan struct{}
waitPortMap sync.WaitGroup
mu sync.Mutex
sentHairCheck bool
@ -599,6 +619,98 @@ func (rs *reportState) stopProbes() {
}
}
func (rs *reportState) setOptBool(b *opt.Bool, v bool) {
rs.mu.Lock()
defer rs.mu.Unlock()
b.Set(v)
}
func (rs *reportState) probePortMapServices() {
defer rs.waitPortMap.Done()
gw, myIP, ok := interfaces.LikelyHomeRouterIP()
if !ok {
return
}
rs.setOptBool(&rs.report.UPnP, false)
rs.setOptBool(&rs.report.PMP, false)
rs.setOptBool(&rs.report.PCP, false)
port1900 := netaddr.IPPort{IP: gw, Port: 1900}.UDPAddr()
port5351 := netaddr.IPPort{IP: gw, Port: 5351}.UDPAddr()
rs.c.logf("probePortMapServices: me %v -> gw %v", myIP, gw)
// Create a UDP4 socket used just for querying for UPnP, NAT-PMP, and PCP.
uc, err := netns.Listener().ListenPacket(context.Background(), "udp4", ":0")
if err != nil {
rs.c.logf("probePortMapServices: %v", err)
return
}
defer uc.Close()
tempPort := uc.LocalAddr().(*net.UDPAddr).Port
uc.SetReadDeadline(time.Now().Add(100 * time.Millisecond))
// Send request packets for all three protocols.
uc.WriteTo(uPnPPacket, port1900)
uc.WriteTo(pmpPacket, port5351)
uc.WriteTo(pcpPacket(myIP, tempPort, false), port5351)
res := make([]byte, 1500)
for {
n, addr, err := uc.ReadFrom(res)
if err != nil {
return
}
switch addr.(*net.UDPAddr).Port {
case 1900:
if mem.Contains(mem.B(res[:n]), mem.S(":InternetGatewayDevice:")) {
rs.setOptBool(&rs.report.UPnP, true)
}
case 5351:
if n == 12 && res[0] == 0x00 { // right length and version 0
rs.setOptBool(&rs.report.PMP, true)
}
if n == 60 && res[0] == 0x02 { // right length and version 2
rs.setOptBool(&rs.report.PCP, true)
// Delete the mapping.
uc.WriteTo(pcpPacket(myIP, tempPort, true), port5351)
}
}
}
}
var pmpPacket = []byte{0, 0} // version 0, opcode 0 = "Public address request"
var uPnPPacket = []byte("M-SEARCH * HTTP/1.1\r\n" +
"HOST: 239.255.255.250:1900\r\n" +
"ST: ssdp:all\r\n" +
"MAN: \"ssdp:discover\"\r\n" +
"MX: 2\r\n\r\n")
var v4unspec, _ = netaddr.ParseIP("0.0.0.0")
func pcpPacket(myIP netaddr.IP, mapToLocalPort int, delete bool) []byte {
const udpProtoNumber = 17
lifetimeSeconds := uint32(1)
if delete {
lifetimeSeconds = 0
}
const opMap = 1
pkt := make([]byte, (32+32+128)/8+(96+8+24+16+16+128)/8)
pkt[0] = 2 // version
pkt[1] = opMap
binary.BigEndian.PutUint32(pkt[4:8], lifetimeSeconds)
myIP16 := myIP.As16()
copy(pkt[8:], myIP16[:])
rand.Read(pkt[24 : 24+12])
pkt[36] = udpProtoNumber
binary.BigEndian.PutUint16(pkt[40:], uint16(mapToLocalPort))
v4unspec16 := v4unspec.As16()
copy(pkt[40:], v4unspec16[:])
return pkt
}
func newReport() *Report {
return &Report{
RegionLatency: make(map[int]time.Duration),
@ -671,6 +783,9 @@ func (c *Client) GetReport(ctx context.Context, dm *tailcfg.DERPMap) (*Report, e
}
defer rs.pc4Hair.Close()
rs.waitPortMap.Add(1)
go rs.probePortMapServices()
// At least the Apple Airport Extreme doesn't allow hairpin
// sends from a private socket until it's seen traffic from
// that src IP:port to something else out on the internet.
@ -738,6 +853,7 @@ func (c *Client) GetReport(ctx context.Context, dm *tailcfg.DERPMap) (*Report, e
}
rs.waitHairCheck(ctx)
rs.waitPortMap.Wait()
rs.stopTimers()
// Try HTTPS latency check if all STUN probes failed due to UDP presumably being blocked.
@ -861,6 +977,11 @@ func (c *Client) logConciseReport(r *Report, dm *tailcfg.DERPMap) {
fmt.Fprintf(w, " v6=%v", r.IPv6)
fmt.Fprintf(w, " mapvarydest=%v", r.MappingVariesByDestIP)
fmt.Fprintf(w, " hair=%v", r.HairPinning)
if r.AnyPortMappingChecked() {
fmt.Fprintf(w, " portmap=%v%v%v", conciseOptBool(r.UPnP, "U"), conciseOptBool(r.PMP, "M"), conciseOptBool(r.PCP, "C"))
} else {
fmt.Fprintf(w, " portmap=?")
}
if r.GlobalV4 != "" {
fmt.Fprintf(w, " v4a=%v", r.GlobalV4)
}
@ -1069,3 +1190,17 @@ func maxDurationValue(m map[int]time.Duration) (max time.Duration) {
}
return max
}
func conciseOptBool(b opt.Bool, trueVal string) string {
if b == "" {
return "_"
}
v, ok := b.Get()
if !ok {
return "x"
}
if v {
return trueVal
}
return ""
}

31
net/netcheck/netcheck_test.go
View File

@ -100,6 +100,9 @@ func TestWorksWhenUDPBlocked(t *testing.T) {
t.Fatal(err)
}
want := newReport()
r.UPnP = ""
r.PMP = ""
r.PCP = ""
if !reflect.DeepEqual(r, want) {
t.Errorf("mismatch\n got: %+v\nwant: %+v\n", r, want)
@ -463,7 +466,7 @@ func TestLogConciseReport(t *testing.T) {
{
name: "no_udp",
r: &Report{},
want: "udp=false v4=false v6=false mapvarydest= hair= derp=0",
want: "udp=false v4=false v6=false mapvarydest= hair= portmap=? derp=0",
},
{
name: "ipv4_one_region",
@ -478,7 +481,7 @@ func TestLogConciseReport(t *testing.T) {
1: 10 * ms,
},
},
want: "udp=true v6=false mapvarydest= hair= derp=1 derpdist=1v4:10ms",
want: "udp=true v6=false mapvarydest= hair= portmap=? derp=1 derpdist=1v4:10ms",
},
{
name: "ipv4_all_region",
@ -497,7 +500,7 @@ func TestLogConciseReport(t *testing.T) {
3: 30 * ms,
},
},
want: "udp=true v6=false mapvarydest= hair= derp=1 derpdist=1v4:10ms,2v4:20ms,3v4:30ms",
want: "udp=true v6=false mapvarydest= hair= portmap=? derp=1 derpdist=1v4:10ms,2v4:20ms,3v4:30ms",
},
{
name: "ipboth_all_region",
@ -522,7 +525,27 @@ func TestLogConciseReport(t *testing.T) {
3: 30 * ms,
},
},
want: "udp=true v6=true mapvarydest= hair= derp=1 derpdist=1v4:10ms,1v6:10ms,2v4:20ms,2v6:20ms,3v4:30ms,3v6:30ms",
want: "udp=true v6=true mapvarydest= hair= portmap=? derp=1 derpdist=1v4:10ms,1v6:10ms,2v4:20ms,2v6:20ms,3v4:30ms,3v6:30ms",
},
{
name: "portmap_all",
r: &Report{
UDP: true,
UPnP: "true",
PMP: "true",
PCP: "true",
},
want: "udp=true v4=false v6=false mapvarydest= hair= portmap=UMC derp=0",
},
{
name: "portmap_some",
r: &Report{
UDP: true,
UPnP: "true",
PMP: "false",
PCP: "true",
},
want: "udp=true v4=false v6=false mapvarydest= hair= portmap=UC derp=0",
},
}
for _, tt := range tests {

42
tailcfg/tailcfg.go
View File

@ -310,6 +310,18 @@ type NetInfo struct {
// WorkingUDP is whether UDP works.
WorkingUDP opt.Bool
// UPnP is whether UPnP appears present on the LAN.
// Empty means not checked.
UPnP opt.Bool
// PMP is whether NAT-PMP appears present on the LAN.
// Empty means not checked.
PMP opt.Bool
// PCP is whether PCP appears present on the LAN.
// Empty means not checked.
PCP opt.Bool
// PreferredDERP is this node's preferred DERP server
// for incoming traffic. The node might be be temporarily
// connected to multiple DERP servers (to send to other nodes)
@ -338,9 +350,32 @@ func (ni *NetInfo) String() string {
if ni == nil {
return "NetInfo(nil)"
}
return fmt.Sprintf("NetInfo{varies=%v hairpin=%v ipv6=%v udp=%v derp=#%v link=%q}",
return fmt.Sprintf("NetInfo{varies=%v hairpin=%v ipv6=%v udp=%v derp=#%v portmap=%v link=%q}",
ni.MappingVariesByDestIP, ni.HairPinning, ni.WorkingIPv6,
ni.WorkingUDP, ni.PreferredDERP, ni.LinkType)
ni.WorkingUDP, ni.PreferredDERP,
ni.portMapSummary(),
ni.LinkType)
}
func (ni *NetInfo) portMapSummary() string {
if ni.UPnP == "" && ni.PMP == "" && ni.PCP == "" {
return "na"
}
return conciseOptBool(ni.UPnP, "U") + conciseOptBool(ni.PMP, "M") + conciseOptBool(ni.PCP, "C")
}
func conciseOptBool(b opt.Bool, trueVal string) string {
if b == "" {
return "_"
}
v, ok := b.Get()
if !ok {
return "x"
}
if v {
return trueVal
}
return ""
}
// BasicallyEqual reports whether ni and ni2 are basically equal, ignoring
@ -356,6 +391,9 @@ func (ni *NetInfo) BasicallyEqual(ni2 *NetInfo) bool {
ni.HairPinning == ni2.HairPinning &&
ni.WorkingIPv6 == ni2.WorkingIPv6 &&
ni.WorkingUDP == ni2.WorkingUDP &&
ni.UPnP == ni2.UPnP &&
ni.PMP == ni2.PMP &&
ni.PCP == ni2.PCP &&
ni.PreferredDERP == ni2.PreferredDERP &&
ni.LinkType == ni2.LinkType
}

3
tailcfg/tailcfg_test.go
View File

@ -329,6 +329,9 @@ func TestNetInfoFields(t *testing.T) {
"HairPinning",
"WorkingIPv6",
"WorkingUDP",
"UPnP",
"PMP",
"PCP",
"PreferredDERP",
"LinkType",
"DERPLatency",

3
wgengine/magicsock/magicsock.go
View File

@ -389,6 +389,9 @@ func (c *Conn) updateNetInfo(ctx context.Context) (*netcheck.Report, error) {
DERPLatency: map[string]float64{},
MappingVariesByDestIP: report.MappingVariesByDestIP,
HairPinning: report.HairPinning,
UPnP: report.UPnP,
PMP: report.PMP,
PCP: report.PCP,
}
for rid, d := range report.RegionV4Latency {
ni.DERPLatency[fmt.Sprintf("%d-v4", rid)] = d.Seconds()