p2p/nat: add test for UPnP auto discovery via SSDP

The test listens for multicast UDP packets on the default interface
because I couldn't get it to work reliably on loopback without massive
changes to goupnp. This means that the test might fail when there is a
UPnP-enabled router attached on that interface. I checked that locally
by looping the test and it passes reliably because the local SSDP server
always responds faster.

p2p/nat/natupnp_test.go

+package nat
+
+import (
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+	"strings"
+	"testing"
+
+	"github.com/huin/goupnp/httpu"
+)
+
+func TestUPNP_DDWRT(t *testing.T) {
+	dev := &fakeIGD{
+		t: t,
+		ssdpResp: "HTTP/1.1 200 OK\r\n" +
+			"Cache-Control: max-age=300\r\n" +
+			"Date: Sun, 10 May 2015 10:05:33 GMT\r\n" +
+			"Ext: \r\n" +
+			"Location: http://{{listenAddr}}/InternetGatewayDevice.xml\r\n" +
+			"Server: POSIX UPnP/1.0 DD-WRT Linux/V24\r\n" +
+			"ST: urn:schemas-upnp-org:device:WANConnectionDevice:1\r\n" +
+			"USN: uuid:CB2471CC-CF2E-9795-8D9C-E87B34C16800::urn:schemas-upnp-org:device:WANConnectionDevice:1\r\n" +
+			"\r\n",
+		httpResps: map[string]string{
+			"GET /InternetGatewayDevice.xml": `
+				 <?xml version="1.0"?>
+				 <root xmlns="urn:schemas-upnp-org:device-1-0">
+					 <specVersion>
+						 <major>1</major>
+						 <minor>0</minor>
+					 </specVersion>
+					 <device>
+						 <deviceType>urn:schemas-upnp-org:device:InternetGatewayDevice:1</deviceType>
+						 <manufacturer>DD-WRT</manufacturer>
+						 <manufacturerURL>http://www.dd-wrt.com</manufacturerURL>
+						 <modelDescription>Gateway</modelDescription>
+						 <friendlyName>Asus RT-N16:DD-WRT</friendlyName>
+						 <modelName>Asus RT-N16</modelName>
+						 <modelNumber>V24</modelNumber>
+						 <serialNumber>0000001</serialNumber>
+						 <modelURL>http://www.dd-wrt.com</modelURL>
+						 <UDN>uuid:A13AB4C3-3A14-E386-DE6A-EFEA923A06FE</UDN>
+						 <serviceList>
+							 <service>
+								 <serviceType>urn:schemas-upnp-org:service:Layer3Forwarding:1</serviceType>
+								 <serviceId>urn:upnp-org:serviceId:L3Forwarding1</serviceId>
+								 <SCPDURL>/x_layer3forwarding.xml</SCPDURL>
+								 <controlURL>/control?Layer3Forwarding</controlURL>
+								 <eventSubURL>/event?Layer3Forwarding</eventSubURL>
+							 </service>
+						 </serviceList>
+						 <deviceList>
+							 <device>
+								 <deviceType>urn:schemas-upnp-org:device:WANDevice:1</deviceType>
+								 <friendlyName>WANDevice</friendlyName>
+								 <manufacturer>DD-WRT</manufacturer>
+								 <manufacturerURL>http://www.dd-wrt.com</manufacturerURL>
+								 <modelDescription>Gateway</modelDescription>
+								 <modelName>router</modelName>
+								 <modelURL>http://www.dd-wrt.com</modelURL>
+								 <UDN>uuid:48FD569B-F9A9-96AE-4EE6-EB403D3DB91A</UDN>
+								 <serviceList>
+									 <service>
+										 <serviceType>urn:schemas-upnp-org:service:WANCommonInterfaceConfig:1</serviceType>
+										 <serviceId>urn:upnp-org:serviceId:WANCommonIFC1</serviceId>
+										 <SCPDURL>/x_wancommoninterfaceconfig.xml</SCPDURL>
+										 <controlURL>/control?WANCommonInterfaceConfig</controlURL>
+										 <eventSubURL>/event?WANCommonInterfaceConfig</eventSubURL>
+									 </service>
+								 </serviceList>
+								 <deviceList>
+									 <device>
+										 <deviceType>urn:schemas-upnp-org:device:WANConnectionDevice:1</deviceType>
+										 <friendlyName>WAN Connection Device</friendlyName>
+										 <manufacturer>DD-WRT</manufacturer>
+										 <manufacturerURL>http://www.dd-wrt.com</manufacturerURL>
+										 <modelDescription>Gateway</modelDescription>
+										 <modelName>router</modelName>
+										 <modelURL>http://www.dd-wrt.com</modelURL>
+										 <UDN>uuid:CB2471CC-CF2E-9795-8D9C-E87B34C16800</UDN>
+										 <serviceList>
+											 <service>
+												 <serviceType>urn:schemas-upnp-org:service:WANIPConnection:1</serviceType>
+												 <serviceId>urn:upnp-org:serviceId:WANIPConn1</serviceId>
+												 <SCPDURL>/x_wanipconnection.xml</SCPDURL>
+												 <controlURL>/control?WANIPConnection</controlURL>
+												 <eventSubURL>/event?WANIPConnection</eventSubURL>
+											 </service>
+										 </serviceList>
+									 </device>
+								 </deviceList>
+							 </device>
+							 <device>
+								 <deviceType>urn:schemas-upnp-org:device:LANDevice:1</deviceType>
+								 <friendlyName>LANDevice</friendlyName>
+								 <manufacturer>DD-WRT</manufacturer>
+								 <manufacturerURL>http://www.dd-wrt.com</manufacturerURL>
+								 <modelDescription>Gateway</modelDescription>
+								 <modelName>router</modelName>
+								 <modelURL>http://www.dd-wrt.com</modelURL>
+								 <UDN>uuid:04021998-3B35-2BDB-7B3C-99DA4435DA09</UDN>
+								 <serviceList>
+									 <service>
+										 <serviceType>urn:schemas-upnp-org:service:LANHostConfigManagement:1</serviceType>
+										 <serviceId>urn:upnp-org:serviceId:LANHostCfg1</serviceId>
+										 <SCPDURL>/x_lanhostconfigmanagement.xml</SCPDURL>
+										 <controlURL>/control?LANHostConfigManagement</controlURL>
+										 <eventSubURL>/event?LANHostConfigManagement</eventSubURL>
+									 </service>
+								 </serviceList>
+							 </device>
+						 </deviceList>
+						 <presentationURL>http://{{listenAddr}}</presentationURL>
+					 </device>
+				 </root>
+			`,
+			// The response to our GetNATRSIPStatus call. This
+			// particular implementation has a bug where the elements
+			// inside u:GetNATRSIPStatusResponse are not properly
+			// namespaced.
+			"POST /control?WANIPConnection": `
+				 <s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" s:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
+				 <s:Body>
+				 <u:GetNATRSIPStatusResponse xmlns:u="urn:schemas-upnp-org:service:WANIPConnection:1">
+				 <NewRSIPAvailable>0</NewRSIPAvailable>
+				 <NewNATEnabled>1</NewNATEnabled>
+				 </u:GetNATRSIPStatusResponse>
+				 </s:Body>
+				 </s:Envelope>
+			`,
+		},
+	}
+	if err := dev.listen(); err != nil {
+		t.Skipf("cannot listen: %v", err)
+	}
+	dev.serve()
+	defer dev.close()
+
+	// Attempt to discover the fake device.
+	discovered := discoverUPnP()
+	if discovered == nil {
+		t.Fatalf("not discovered")
+	}
+	upnp, _ := discovered.(*upnp)
+	if upnp.service != "IGDv1-IP1" {
+		t.Errorf("upnp.service mismatch: got %q, want %q", upnp.service, "IGDv1-IP1")
+	}
+	wantURL := "http://" + dev.listener.Addr().String() + "/InternetGatewayDevice.xml"
+	if upnp.dev.URLBaseStr != wantURL {
+		t.Errorf("upnp.dev.URLBaseStr mismatch: got %q, want %q", upnp.dev.URLBaseStr, wantURL)
+	}
+}
+
+// fakeIGD presents itself as a discoverable UPnP device which sends
+// canned responses to HTTPU and HTTP requests.
+type fakeIGD struct {
+	t *testing.T // for logging
+
+	listener      net.Listener
+	mcastListener *net.UDPConn
+
+	// This should be a complete HTTP response (including headers).
+	// It is sent as the response to any sspd packet. Any occurrence
+	// of "{{listenAddr}}" is replaced with the actual TCP listen
+	// address of the HTTP server.
+	ssdpResp string
+	// This one should contain XML payloads for all requests
+	// performed. The keys contain method and path, e.g. "GET /foo/bar".
+	// As with ssdpResp, "{{listenAddr}}" is replaced with the TCP
+	// listen address.
+	httpResps map[string]string
+}
+
+// httpu.Handler
+func (dev *fakeIGD) ServeMessage(r *http.Request) {
+	dev.t.Logf(`HTTPU request %s %s`, r.Method, r.RequestURI)
+	conn, err := net.Dial("udp4", r.RemoteAddr)
+	if err != nil {
+		fmt.Printf("reply Dial error: %v", err)
+		return
+	}
+	defer conn.Close()
+	io.WriteString(conn, dev.replaceListenAddr(dev.ssdpResp))
+}
+
+// http.Handler
+func (dev *fakeIGD) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	if resp, ok := dev.httpResps[r.Method+" "+r.RequestURI]; ok {
+		dev.t.Logf(`HTTP request "%s %s" --> %d`, r.Method, r.RequestURI, 200)
+		io.WriteString(w, dev.replaceListenAddr(resp))
+	} else {
+		dev.t.Logf(`HTTP request "%s %s" --> %d`, r.Method, r.RequestURI, 404)
+		w.WriteHeader(http.StatusNotFound)
+	}
+}
+
+func (dev *fakeIGD) replaceListenAddr(resp string) string {
+	return strings.Replace(resp, "{{listenAddr}}", dev.listener.Addr().String(), -1)
+}
+
+func (dev *fakeIGD) listen() (err error) {
+	if dev.listener, err = net.Listen("tcp", "127.0.0.1:0"); err != nil {
+		return err
+	}
+	laddr := &net.UDPAddr{IP: net.ParseIP("239.255.255.250"), Port: 1900}
+	if dev.mcastListener, err = net.ListenMulticastUDP("udp", nil, laddr); err != nil {
+		dev.listener.Close()
+		return err
+	}
+	return nil
+}
+
+func (dev *fakeIGD) serve() {
+	go httpu.Serve(dev.mcastListener, dev)
+	go http.Serve(dev.listener, dev)
+}
+
+func (dev *fakeIGD) close() {
+	dev.mcastListener.Close()
+	dev.listener.Close()
+}