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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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153
net/netcheck/netcheck.go
View File

@@ -8,7 +8,9 @@ package netcheck
import (
"bufio"
"context"
"crypto/rand"
"crypto/tls"
"encoding/binary"
"errors"
"fmt"
"io"
@@ -21,6 +23,7 @@ import (
"time"
"github.com/tcnksm/go-httpstat"
"go4.org/mem"
"inet.af/netaddr"
"tailscale.com/derp/derphttp"
"tailscale.com/net/dnscache"
@@ -34,15 +37,26 @@ import (
)
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 ""
}