// Copyright (c) Tailscale Inc & AUTHORS // SPDX-License-Identifier: BSD-3-Clause package portmapper import ( "bytes" "fmt" "net" "net/http" "net/http/httptest" "net/netip" "sync" "sync/atomic" "testing" "tailscale.com/control/controlknobs" "tailscale.com/net/netaddr" "tailscale.com/syncs" "tailscale.com/types/logger" ) // TestIGD is an IGD (Internet Gateway Device) for testing. It supports fake // implementations of NAT-PMP, PCP, and/or UPnP to test clients against. type TestIGD struct { upnpConn net.PacketConn // for UPnP discovery pxpConn net.PacketConn // for NAT-PMP and/or PCP ts *httptest.Server upnpHTTP syncs.AtomicValue[http.Handler] logf logger.Logf closed atomic.Bool // do* will log which packets are sent, but will not reply to unexpected packets. doPMP bool doPCP bool doUPnP bool mu sync.Mutex // guards below counters igdCounters } // TestIGDOptions are options type TestIGDOptions struct { PMP bool PCP bool UPnP bool // TODO: more options for 3 flavors of UPnP services } type igdCounters struct { numUPnPDiscoRecv int32 numUPnPOtherUDPRecv int32 numPMPRecv int32 numPCPRecv int32 numPCPDiscoRecv int32 numPCPMapRecv int32 numPCPOtherRecv int32 numPMPPublicAddrRecv int32 numPMPBogusRecv int32 numFailedWrites int32 invalidPCPMapPkt int32 } func NewTestIGD(logf logger.Logf, t TestIGDOptions) (*TestIGD, error) { d := &TestIGD{ doPMP: t.PMP, doPCP: t.PCP, doUPnP: t.UPnP, } d.logf = func(msg string, args ...any) { // Don't log after the device has closed; // stray trailing logging angers testing.T.Logf. if d.closed.Load() { return } logf(msg, args...) } var err error if d.upnpConn, err = testListenUDP(); err != nil { return nil, err } if d.pxpConn, err = testListenUDP(); err != nil { d.upnpConn.Close() return nil, err } d.ts = httptest.NewServer(http.HandlerFunc(d.serveUPnPHTTP)) go d.serveUPnPDiscovery() go d.servePxP() return d, nil } func testListenUDP() (net.PacketConn, error) { return net.ListenPacket("udp4", "127.0.0.1:0") } func (d *TestIGD) TestPxPPort() uint16 { return uint16(d.pxpConn.LocalAddr().(*net.UDPAddr).Port) } func (d *TestIGD) TestUPnPPort() uint16 { return uint16(d.upnpConn.LocalAddr().(*net.UDPAddr).Port) } func testIPAndGateway() (gw, ip netip.Addr, ok bool) { return netaddr.IPv4(127, 0, 0, 1), netaddr.IPv4(1, 2, 3, 4), true } func (d *TestIGD) Close() error { d.closed.Store(true) d.ts.Close() d.upnpConn.Close() d.pxpConn.Close() return nil } func (d *TestIGD) inc(p *int32) { d.mu.Lock() defer d.mu.Unlock() (*p)++ } func (d *TestIGD) stats() igdCounters { d.mu.Lock() defer d.mu.Unlock() return d.counters } func (d *TestIGD) SetUPnPHandler(h http.Handler) { d.upnpHTTP.Store(h) } func (d *TestIGD) serveUPnPHTTP(w http.ResponseWriter, r *http.Request) { if handler := d.upnpHTTP.Load(); handler != nil { handler.ServeHTTP(w, r) return } http.NotFound(w, r) } func (d *TestIGD) serveUPnPDiscovery() { buf := make([]byte, 1500) for { n, src, err := d.upnpConn.ReadFrom(buf) if err != nil { if !d.closed.Load() { d.logf("serveUPnP failed: %v", err) } return } pkt := buf[:n] if bytes.Equal(pkt, uPnPPacket) { // a super lazy "parse" d.inc(&d.counters.numUPnPDiscoRecv) resPkt := fmt.Appendf(nil, "HTTP/1.1 200 OK\r\nCACHE-CONTROL: max-age=120\r\nST: urn:schemas-upnp-org:device:InternetGatewayDevice:1\r\nUSN: uuid:bee7052b-49e8-3597-b545-55a1e38ac11::urn:schemas-upnp-org:device:InternetGatewayDevice:1\r\nEXT:\r\nSERVER: Tailscale-Test/1.0 UPnP/1.1 MiniUPnPd/2.2.1\r\nLOCATION: %s\r\nOPT: \"http://schemas.upnp.org/upnp/1/0/\"; ns=01\r\n01-NLS: 1627958564\r\nBOOTID.UPNP.ORG: 1627958564\r\nCONFIGID.UPNP.ORG: 1337\r\n\r\n", d.ts.URL+"/rootDesc.xml") if d.doUPnP { _, err = d.upnpConn.WriteTo(resPkt, src) if err != nil { d.inc(&d.counters.numFailedWrites) } } } else { d.inc(&d.counters.numUPnPOtherUDPRecv) } } } // servePxP serves NAT-PMP and PCP, which share a port number. func (d *TestIGD) servePxP() { buf := make([]byte, 1500) for { n, a, err := d.pxpConn.ReadFrom(buf) if err != nil { if !d.closed.Load() { d.logf("servePxP failed: %v", err) } return } src := netaddr.Unmap(a.(*net.UDPAddr).AddrPort()) if !src.IsValid() { panic("bogus addr") } pkt := buf[:n] if len(pkt) < 2 { continue } ver := pkt[0] switch ver { default: continue case pmpVersion: d.handlePMPQuery(pkt, src) case pcpVersion: d.handlePCPQuery(pkt, src) } } } func (d *TestIGD) handlePMPQuery(pkt []byte, src netip.AddrPort) { d.inc(&d.counters.numPMPRecv) if len(pkt) < 2 { return } op := pkt[1] switch op { case pmpOpMapPublicAddr: if len(pkt) != 2 { d.inc(&d.counters.numPMPBogusRecv) return } d.inc(&d.counters.numPMPPublicAddrRecv) } // TODO } func (d *TestIGD) handlePCPQuery(pkt []byte, src netip.AddrPort) { d.inc(&d.counters.numPCPRecv) if len(pkt) < 24 { return } op := pkt[1] pktSrcBytes := [16]byte{} copy(pktSrcBytes[:], pkt[8:24]) pktSrc := netip.AddrFrom16(pktSrcBytes).Unmap() if pktSrc != src.Addr() { // TODO this error isn't fatal but should be rejected by server. // Since it's a test it's difficult to get them the same though. d.logf("mismatch of packet source and source IP: got %v, expected %v", pktSrc, src.Addr()) } switch op { case pcpOpAnnounce: d.inc(&d.counters.numPCPDiscoRecv) if !d.doPCP { return } resp := buildPCPDiscoResponse(pkt) if _, err := d.pxpConn.WriteTo(resp, net.UDPAddrFromAddrPort(src)); err != nil { d.inc(&d.counters.numFailedWrites) } case pcpOpMap: if len(pkt) < 60 { d.logf("got too short packet for pcp op map: %v", pkt) d.inc(&d.counters.invalidPCPMapPkt) return } d.inc(&d.counters.numPCPMapRecv) if !d.doPCP { return } resp := buildPCPMapResponse(pkt) d.pxpConn.WriteTo(resp, net.UDPAddrFromAddrPort(src)) default: // unknown op code, ignore it for now. d.inc(&d.counters.numPCPOtherRecv) return } } func newTestClient(t *testing.T, igd *TestIGD) *Client { var c *Client c = NewClient(t.Logf, nil, nil, new(controlknobs.Knobs), func() { t.Logf("port map changed") t.Logf("have mapping: %v", c.HaveMapping()) }) c.testPxPPort = igd.TestPxPPort() c.testUPnPPort = igd.TestUPnPPort() c.SetGatewayLookupFunc(testIPAndGateway) return c }