net/portmapper: add upnp port mapping

Add in UPnP portmapping, using goupnp library in order to get the UPnP client and run the portmapping functions. This rips out anywhere where UPnP used to be in portmapping, and has a flow separate from PMP and PCP. RELNOTE=portmapper now supports UPnP mappings Fixes #682 Updates #2109 Signed-off-by: julianknodt <julianknodt@gmail.com>
2025-08-15 07:27:30 +00:00 · 2021-06-22 15:29:01 -07:00
parent 236eb4d04d
commit 1bb6abc604
14 changed files with 432 additions and 53 deletions
--- a/net/portmapper/portmapper.go
+++ b/net/portmapper/portmapper.go
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

-// Package portmapper is a UDP port mapping client. It currently only does
-// NAT-PMP, but will likely do UPnP and perhaps PCP later.
+// Package portmapper is a UDP port mapping client. It currently allows for mapping over
+// NAT-PMP and UPnP, but will perhaps do PCP later.
 package portmapper

 import (
@@ -17,7 +17,6 @@ import (
 	"sync"
 	"time"

-	"go4.org/mem"
 	"inet.af/netaddr"
 	"tailscale.com/net/interfaces"
 	"tailscale.com/net/netns"
@@ -66,15 +65,34 @@ type Client struct {
 	pcpSawTime  time.Time // time we last saw PCP was available
 	uPnPSawTime time.Time // time we last saw UPnP was available

-	localPort  uint16
-	pmpMapping *pmpMapping // non-nil if we have a PMP mapping
+	localPort uint16
+
+	mapping mapping // non-nil if we have a mapping
+}
+
+// mapping represents a created port-mapping over some protocol.  It specifies a lease duration,
+// how to release the mapping, and whether the map is still valid.
+//
+// After a mapping is created, it should be immutable, and thus reads should be safe across
+// concurrent goroutines.
+type mapping interface {
+	// Release will attempt to unmap the established port mapping. It will block until completion,
+	// but can be called asynchronously. Release should be idempotent, and thus even if called
+	// multiple times should not cause additional side-effects.
+	Release(context.Context)
+	// goodUntil will return the lease time that the mapping is valid for.
+	GoodUntil() time.Time
+	// renewAfter returns the earliest time that the mapping should be renewed.
+	RenewAfter() time.Time
+	// externalIPPort indicates what port the mapping can be reached from on the outside.
+	External() netaddr.IPPort
 }

 // HaveMapping reports whether we have a current valid mapping.
 func (c *Client) HaveMapping() bool {
 	c.mu.Lock()
 	defer c.mu.Unlock()
-	return c.pmpMapping != nil && c.pmpMapping.goodUntil.After(time.Now())
+	return c.mapping != nil && c.mapping.GoodUntil().After(time.Now())
 }

 // pmpMapping is an already-created PMP mapping.
@@ -94,9 +112,13 @@ func (m *pmpMapping) externalValid() bool {
 	return !m.external.IP().IsZero() && m.external.Port() != 0
 }

-// release does a best effort fire-and-forget release of the PMP mapping m.
-func (m *pmpMapping) release() {
-	uc, err := netns.Listener().ListenPacket(context.Background(), "udp4", ":0")
+func (p *pmpMapping) GoodUntil() time.Time     { return p.goodUntil }
+func (p *pmpMapping) RenewAfter() time.Time    { return p.renewAfter }
+func (p *pmpMapping) External() netaddr.IPPort { return p.external }
+
+// Release does a best effort fire-and-forget release of the PMP mapping m.
+func (m *pmpMapping) Release(ctx context.Context) {
+	uc, err := netns.Listener().ListenPacket(ctx, "udp4", ":0")
 	if err != nil {
 		return
 	}
@@ -166,7 +188,6 @@ func (c *Client) gatewayAndSelfIP() (gw, myIP netaddr.IP, ok bool) {
 		gw = netaddr.IP{}
 		myIP = netaddr.IP{}
 	}
-
 	c.mu.Lock()
 	defer c.mu.Unlock()

@@ -179,11 +200,11 @@ func (c *Client) gatewayAndSelfIP() (gw, myIP netaddr.IP, ok bool) {
 }

 func (c *Client) invalidateMappingsLocked(releaseOld bool) {
-	if c.pmpMapping != nil {
+	if c.mapping != nil {
 		if releaseOld {
-			c.pmpMapping.release()
+			c.mapping.Release(context.Background())
 		}
-		c.pmpMapping = nil
+		c.mapping = nil
 	}
 	c.pmpPubIP = netaddr.IP{}
 	c.pmpPubIPTime = time.Time{}
@@ -262,12 +283,12 @@ func (c *Client) GetCachedMappingOrStartCreatingOne() (external netaddr.IPPort,

 	// Do we have an existing mapping that's valid?
 	now := time.Now()
-	if m := c.pmpMapping; m != nil {
-		if now.Before(m.goodUntil) {
-			if now.After(m.renewAfter) {
+	if m := c.mapping; m != nil {
+		if now.Before(m.GoodUntil()) {
+			if now.After(m.RenewAfter()) {
 				c.maybeStartMappingLocked()
 			}
-			return m.external, true
+			return m.External(), true
 		}
 	}

@@ -315,9 +336,10 @@ func (c *Client) createOrGetMapping(ctx context.Context) (external netaddr.IPPor

 	c.mu.Lock()
 	localPort := c.localPort
+	internalAddr := netaddr.IPPortFrom(myIP, localPort)
 	m := &pmpMapping{
 		gw:       gw,
-		internal: netaddr.IPPortFrom(myIP, localPort),
+		internal: internalAddr,
 	}

 	// prevPort is the port we had most previously, if any. We try
@@ -326,13 +348,13 @@ func (c *Client) createOrGetMapping(ctx context.Context) (external netaddr.IPPor

 	// Do we have an existing mapping that's valid?
 	now := time.Now()
-	if m := c.pmpMapping; m != nil {
-		if now.Before(m.renewAfter) {
+	if m := c.mapping; m != nil {
+		if now.Before(m.RenewAfter()) {
 			defer c.mu.Unlock()
-			return m.external, nil
+			return m.External(), nil
 		}
 		// The mapping might still be valid, so just try to renew it.
-		prevPort = m.external.Port()
+		prevPort = m.External().Port()
 	}

 	// If we just did a Probe (e.g. via netchecker) but didn't
@@ -344,6 +366,10 @@ func (c *Client) createOrGetMapping(ctx context.Context) (external netaddr.IPPor
 	}
 	if c.lastProbe.After(now.Add(-5*time.Second)) && !haveRecentPMP {
 		c.mu.Unlock()
+		// fallback to UPnP portmapping
+		if mapping, ok := c.getUPnPPortMapping(ctx, gw, internalAddr, prevPort); ok {
+			return mapping, nil
+		}
 		return netaddr.IPPort{}, NoMappingError{ErrNoPortMappingServices}
 	}

@@ -381,6 +407,10 @@ func (c *Client) createOrGetMapping(ctx context.Context) (external netaddr.IPPor
 			if ctx.Err() == context.Canceled {
 				return netaddr.IPPort{}, err
 			}
+			// fallback to UPnP portmapping
+			if mapping, ok := c.getUPnPPortMapping(ctx, gw, internalAddr, prevPort); ok {
+				return mapping, nil
+			}
 			return netaddr.IPPort{}, NoMappingError{ErrNoPortMappingServices}
 		}
 		srcu := srci.(*net.UDPAddr)
@@ -413,7 +443,7 @@ func (c *Client) createOrGetMapping(ctx context.Context) (external netaddr.IPPor
 		if m.externalValid() {
 			c.mu.Lock()
 			defer c.mu.Unlock()
-			c.pmpMapping = m
+			c.mapping = m
 			return m.external, nil
 		}
 	}
@@ -530,9 +560,27 @@ func (c *Client) Probe(ctx context.Context) (res ProbeResult, err error) {
 	defer cancel()
 	defer closeCloserOnContextDone(ctx, uc)()

+	if c.sawUPnPRecently() {
+		res.UPnP = true
+	} else {
+		hasUPnP := make(chan bool, 1)
+		defer func() {
+			res.UPnP = <-hasUPnP
+		}()
+		go func() {
+			client, err := getUPnPClient(ctx, gw)
+			if err == nil && client != nil {
+				hasUPnP <- true
+				c.mu.Lock()
+				c.uPnPSawTime = time.Now()
+				c.mu.Unlock()
+			}
+			close(hasUPnP)
+		}()
+	}
+
 	pcpAddr := netaddr.IPPortFrom(gw, pcpPort).UDPAddr()
 	pmpAddr := netaddr.IPPortFrom(gw, pmpPort).UDPAddr()
-	upnpAddr := netaddr.IPPortFrom(gw, upnpPort).UDPAddr()

 	// Don't send probes to services that we recently learned (for
 	// the same gw/myIP) are available. See
@@ -547,16 +595,11 @@ func (c *Client) Probe(ctx context.Context) (res ProbeResult, err error) {
 	} else {
 		uc.WriteTo(pcpAnnounceRequest(myIP), pcpAddr)
 	}
-	if c.sawUPnPRecently() {
-		res.UPnP = true
-	} else {
-		uc.WriteTo(uPnPPacket, upnpAddr)
-	}

 	buf := make([]byte, 1500)
 	pcpHeard := false // true when we get any PCP response
 	for {
-		if pcpHeard && res.PMP && res.UPnP {
+		if pcpHeard && res.PMP {
 			// Nothing more to discover.
 			return res, nil
 		}
@@ -569,13 +612,6 @@ func (c *Client) Probe(ctx context.Context) (res ProbeResult, err error) {
 		}
 		port := addr.(*net.UDPAddr).Port
 		switch port {
-		case upnpPort:
-			if mem.Contains(mem.B(buf[:n]), mem.S(":InternetGatewayDevice:")) {
-				res.UPnP = true
-				c.mu.Lock()
-				c.uPnPSawTime = time.Now()
-				c.mu.Unlock()
-			}
 		case pcpPort: // same as pmpPort
 			if pres, ok := parsePCPResponse(buf[:n]); ok {
 				if pres.OpCode == pcpOpReply|pcpOpAnnounce {
@@ -687,14 +723,4 @@ func parsePCPResponse(b []byte) (res pcpResponse, ok bool) {
 	return res, true
 }

-const (
-	upnpPort = 1900
-)
-
-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 pmpReqExternalAddrPacket = []byte{0, 0} // version 0, opcode 0 = "Public address request"
--- a/net/portmapper/portmapper_test.go
+++ b/net/portmapper/portmapper_test.go
@@ -17,6 +17,7 @@ func TestCreateOrGetMapping(t *testing.T) {
 		t.Skip("skipping test without HIT_NETWORK=1")
 	}
 	c := NewClient(t.Logf, nil)
+	defer c.Close()
 	c.SetLocalPort(1234)
 	for i := 0; i < 2; i++ {
 		if i > 0 {
@@ -32,12 +33,13 @@ func TestClientProbe(t *testing.T) {
 		t.Skip("skipping test without HIT_NETWORK=1")
 	}
 	c := NewClient(t.Logf, nil)
-	for i := 0; i < 2; i++ {
+	defer c.Close()
+	for i := 0; i < 3; i++ {
 		if i > 0 {
 			time.Sleep(100 * time.Millisecond)
 		}
 		res, err := c.Probe(context.Background())
-		t.Logf("Got: %+v, %v", res, err)
+		t.Logf("Got(t=%dms): %+v, %v", i*100, res, err)
 	}
 }

@@ -46,6 +48,7 @@ func TestClientProbeThenMap(t *testing.T) {
 		t.Skip("skipping test without HIT_NETWORK=1")
 	}
 	c := NewClient(t.Logf, nil)
+	defer c.Close()
 	c.SetLocalPort(1234)
 	res, err := c.Probe(context.Background())
 	t.Logf("Probe: %+v, %v", res, err)
--- a/net/portmapper/upnp.go
+++ b/net/portmapper/upnp.go
@@ -0,0 +1,239 @@
+// Copyright (c) 2021 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 portmapper
+
+import (
+	"context"
+	"fmt"
+	"net/url"
+	"time"
+
+	"github.com/tailscale/goupnp/dcps/internetgateway2"
+	"inet.af/netaddr"
+	"tailscale.com/control/controlknobs"
+)
+
+// References:
+//
+// WANIP Connection v2: http://upnp.org/specs/gw/UPnP-gw-WANIPConnection-v2-Service.pdf
+
+// upnpMapping is a port mapping over the upnp protocol. After being created it is immutable,
+// but the client field may be shared across mapping instances.
+type upnpMapping struct {
+	gw         netaddr.IP
+	external   netaddr.IPPort
+	internal   netaddr.IPPort
+	goodUntil  time.Time
+	renewAfter time.Time
+
+	// client is a connection to a upnp device, and may be reused across different UPnP mappings.
+	client upnpClient
+}
+
+func (u *upnpMapping) GoodUntil() time.Time     { return u.goodUntil }
+func (u *upnpMapping) RenewAfter() time.Time    { return u.renewAfter }
+func (u *upnpMapping) External() netaddr.IPPort { return u.external }
+func (u *upnpMapping) Release(ctx context.Context) {
+	u.client.DeletePortMapping(ctx, "", u.external.Port(), "udp")
+}
+
+// upnpClient is an interface over the multiple different clients exported by goupnp,
+// exposing the functions we need for portmapping. They are auto-generated from XML-specs.
+type upnpClient interface {
+	AddPortMapping(
+		ctx context.Context,
+
+		// remoteHost is the remote device sending packets to this device, in the format of x.x.x.x.
+		// The empty string, "", means any host out on the internet can send packets in.
+		remoteHost string,
+
+		// externalPort is the exposed port of this port mapping. Visible during NAT operations.
+		// 0 will let the router select the port, but there is an additional call,
+		// `AddAnyPortMapping`, which is available on 1 of the 3 possible protocols,
+		// which should be used if available. See `addAnyPortMapping` below, which calls this if
+		// `AddAnyPortMapping` is not supported.
+		externalPort uint16,
+
+		// protocol is whether this is over TCP or UDP. Either "tcp" or "udp".
+		protocol string,
+
+		// internalPort is the port that the gateway device forwards the traffic to.
+		internalPort uint16,
+		// internalClient is the IP address that packets will be forwarded to for this mapping.
+		// Internal client is of the form "x.x.x.x".
+		internalClient string,
+
+		// enabled is whether this portmapping should be enabled or disabled.
+		enabled bool,
+		// portMappingDescription is a user-readable description of this portmapping.
+		portMappingDescription string,
+		// leaseDurationSec is the duration of this portmapping. The value of this argument must be
+		// greater than 0. From the spec, it appears if it is set to 0, it will switch to using
+		// 604800 seconds, but not sure why this is desired. The recommended time is 3600 seconds.
+		leaseDurationSec uint32,
+	) (err error)
+
+	DeletePortMapping(ctx context.Context, remoteHost string, externalPort uint16, protocol string) error
+	GetExternalIPAddress(ctx context.Context) (externalIPAddress string, err error)
+}
+
+// tsPortMappingDesc gets sent to UPnP clients as a human-readable label for the portmapping.
+// It is not used for anything other than labelling.
+const tsPortMappingDesc = "tailscale-portmap"
+
+// addAnyPortMapping abstracts over different UPnP client connections, calling the available
+// AddAnyPortMapping call if available for WAN IP connection v2, otherwise defaulting to the old
+// behavior of calling AddPortMapping with port = 0 to specify a wildcard port.
+func addAnyPortMapping(
+	ctx context.Context,
+	upnp upnpClient,
+	externalPort uint16,
+	internalPort uint16,
+	internalClient string,
+	leaseDuration time.Duration,
+) (newPort uint16, err error) {
+	if upnp, ok := upnp.(*internetgateway2.WANIPConnection2); ok {
+		return upnp.AddAnyPortMapping(
+			ctx,
+			"",
+			externalPort,
+			"udp",
+			internalPort,
+			internalClient,
+			true,
+			tsPortMappingDesc,
+			uint32(leaseDuration.Seconds()),
+		)
+	}
+	err = upnp.AddPortMapping(
+		ctx,
+		"",
+		externalPort,
+		"udp",
+		internalPort,
+		internalClient,
+		true,
+		tsPortMappingDesc,
+		uint32(leaseDuration.Seconds()),
+	)
+	return internalPort, err
+}
+
+// getUPnPClients gets a client for interfacing with UPnP, ignoring the underlying protocol for
+// now.
+// Adapted from https://github.com/huin/goupnp/blob/master/GUIDE.md.
+func getUPnPClient(ctx context.Context, gw netaddr.IP) (upnpClient, error) {
+	if dis, ok := controlknobs.DisableUPnP().Get(); ok && dis {
+		return nil, nil
+	}
+	ctx, cancel := context.WithTimeout(ctx, 250*time.Millisecond)
+	defer cancel()
+	// Attempt to connect over the multiple available connection types concurrently,
+	// returning the fastest.
+
+	// TODO(jknodt): this url seems super brittle? maybe discovery is better but this is faster
+	u, err := url.Parse(fmt.Sprintf("http://%s:5000/rootDesc.xml", gw))
+	if err != nil {
+		return nil, err
+	}
+
+	clients := make(chan upnpClient, 3)
+	go func() {
+		var err error
+		ip1Clients, err := internetgateway2.NewWANIPConnection1ClientsByURL(ctx, u)
+		if err == nil && len(ip1Clients) > 0 {
+			clients <- ip1Clients[0]
+		}
+	}()
+	go func() {
+		ip2Clients, err := internetgateway2.NewWANIPConnection2ClientsByURL(ctx, u)
+		if err == nil && len(ip2Clients) > 0 {
+			clients <- ip2Clients[0]
+		}
+	}()
+	go func() {
+		ppp1Clients, err := internetgateway2.NewWANPPPConnection1ClientsByURL(ctx, u)
+		if err == nil && len(ppp1Clients) > 0 {
+			clients <- ppp1Clients[0]
+		}
+	}()
+
+	select {
+	case client := <-clients:
+		return client, nil
+	case <-ctx.Done():
+		return nil, ctx.Err()
+	}
+}
+
+// getUPnPPortMapping attempts to create a port-mapping over the UPnP protocol. On success,
+// it will return the externally exposed IP and port. Otherwise, it will return a zeroed IP and
+// port and an error.
+func (c *Client) getUPnPPortMapping(
+	ctx context.Context,
+	gw netaddr.IP,
+	internal netaddr.IPPort,
+	prevPort uint16,
+) (external netaddr.IPPort, ok bool) {
+	if dis, ok := controlknobs.DisableUPnP().Get(); ok && dis {
+		return netaddr.IPPort{}, false
+	}
+	now := time.Now()
+	upnp := &upnpMapping{
+		gw:       gw,
+		internal: internal,
+	}
+
+	var client upnpClient
+	var err error
+	c.mu.Lock()
+	oldMapping, ok := c.mapping.(*upnpMapping)
+	c.mu.Unlock()
+	if ok && oldMapping != nil {
+		client = oldMapping.client
+	} else {
+		client, err = getUPnPClient(ctx, gw)
+		if err != nil {
+			return netaddr.IPPort{}, false
+		}
+	}
+	if client == nil {
+		return netaddr.IPPort{}, false
+	}
+
+	var newPort uint16
+	newPort, err = addAnyPortMapping(
+		ctx,
+		client,
+		prevPort,
+		internal.Port(),
+		internal.IP().String(),
+		time.Second*pmpMapLifetimeSec,
+	)
+	if err != nil {
+		return netaddr.IPPort{}, false
+	}
+	// TODO cache this ip somewhere?
+	extIP, err := client.GetExternalIPAddress(ctx)
+	if err != nil {
+		// TODO this doesn't seem right
+		return netaddr.IPPort{}, false
+	}
+	externalIP, err := netaddr.ParseIP(extIP)
+	if err != nil {
+		return netaddr.IPPort{}, false
+	}
+
+	upnp.external = netaddr.IPPortFrom(externalIP, newPort)
+	d := time.Duration(pmpMapLifetimeSec) * time.Second
+	upnp.goodUntil = now.Add(d)
+	upnp.renewAfter = now.Add(d / 2)
+	upnp.client = client
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	c.mapping = upnp
+	c.localPort = newPort
+	return upnp.external, true
+}