disco: add UPnP support

disco/udp.go

@@ -6,12 +6,14 @@ import (
 	"fmt"
 	"log/slog"
 	"net"
+	"net/netip"
 	"strings"
 	"sync"
 	"time"
 
 	cmap "github.com/orcaman/concurrent-map/v2"
 	"github.com/rkonfj/peerguard/peer"
+	"github.com/rkonfj/peerguard/upnp"
 	"tailscale.com/net/stun"
 )
 
@@ -41,6 +43,33 @@ func (c *UDPConn) UDPAddrSends() <-chan *PeerUDPAddrEvent {
 }
 
 func (c *UDPConn) GenerateLocalAddrsSends(peerID peer.PeerID, stunServers []string) {
+	// UPnP
+	go func() {
+		nat, err := upnp.Discover()
+		if err != nil {
+			slog.Debug("UPnP is disabled", "err", err)
+			return
+		}
+		externalIP, err := nat.GetExternalAddress()
+		if err != nil {
+			slog.Debug("UPnP is disabled", "err", err)
+			return
+		}
+		udpPort := int(netip.MustParseAddrPort(c.UDPConn.LocalAddr().String()).Port())
+
+		for i := 0; i < 5; i++ {
+			mappedPort, err := nat.AddPortMapping("udp", udpPort+i, udpPort, "peerguard", 24*3600)
+			if err != nil {
+				continue
+			}
+			c.udpAddrSends <- &PeerUDPAddrEvent{
+				PeerID: peerID,
+				Addr:   &net.UDPAddr{IP: externalIP, Port: mappedPort},
+			}
+			return
+		}
+	}()
+	// LAN
 	for _, addr := range c.localAddrs {
 		uaddr, err := net.ResolveUDPAddr("udp", addr)
 		if err != nil {
@@ -52,6 +81,7 @@ func (c *UDPConn) GenerateLocalAddrsSends(peerID peer.PeerID, stunServers []stri
 			Addr:   uaddr,
 		}
 	}
+	// WAN
 	time.AfterFunc(time.Second, func() {
 		if ctx, ok := c.findPeer(peerID); !ok || !ctx.IPv4Ready() {
 			c.requestSTUN(peerID, stunServers)

upnp/upnp.go

@@ -0,0 +1,368 @@
+package upnp
+
+// Copyright (c) 2024 rkonfj@gmail.com
+// Origin source: https://github.com/jackpal/Taipei-Torrent/blob/6808fdfe24b4db505476ef48b9e288a5e7398f77/torrent/upnp.go
+// Copyright (c) 2024 Jack Palevich (https://github.com/jackpal/Taipei-Torrent/blob/6808fdfe24b4db505476ef48b9e288a5e7398f77/LICENSE)
+//
+
+import (
+	"bytes"
+	"encoding/xml"
+	"errors"
+	"io"
+	"net"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+)
+
+// UPnPNAT Just enough UPnP to be able to forward ports
+type UPnPNAT struct {
+	serviceURL string
+	ourIP      string
+	urnDomain  string
+}
+
+func Discover() (nat *UPnPNAT, err error) {
+	ssdp, err := net.ResolveUDPAddr("udp4", "239.255.255.250:1900")
+	if err != nil {
+		return
+	}
+	conn, err := net.ListenPacket("udp4", ":0")
+	if err != nil {
+		return
+	}
+	socket := conn.(*net.UDPConn)
+	defer socket.Close()
+
+	err = socket.SetDeadline(time.Now().Add(3 * time.Second))
+	if err != nil {
+		return
+	}
+
+	st := "InternetGatewayDevice:1"
+
+	buf := bytes.NewBufferString(
+		"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")
+	message := buf.Bytes()
+	answerBytes := make([]byte, 1024)
+	for i := 0; i < 3; i++ {
+		_, err = socket.WriteToUDP(message, ssdp)
+		if err != nil {
+			return
+		}
+		var n int
+		for {
+			n, _, err = socket.ReadFromUDP(answerBytes)
+			if err != nil {
+				break
+			}
+			answer := string(answerBytes[0:n])
+			if !strings.Contains(answer, st) {
+				continue
+			}
+			// HTTP header field names are case-insensitive.
+			// http://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.2
+			locString := "\r\nlocation:"
+			answer = strings.ToLower(answer)
+			locIndex := strings.Index(answer, locString)
+			if locIndex < 0 {
+				continue
+			}
+			loc := answer[locIndex+len(locString):]
+			endIndex := strings.Index(loc, "\r\n")
+			if endIndex < 0 {
+				continue
+			}
+			locURL := strings.TrimSpace(loc[0:endIndex])
+			var serviceURL, urnDomain string
+			serviceURL, urnDomain, err = getServiceURL(locURL)
+			if err != nil {
+				return
+			}
+			var ourIP net.IP
+			ourIP, err = localIPv4()
+			if err != nil {
+				return
+			}
+			nat = &UPnPNAT{serviceURL: serviceURL, ourIP: ourIP.String(), urnDomain: urnDomain}
+			return
+		}
+	}
+	err = errors.New("upnp port discovery failed")
+	return
+}
+
+type Envelope struct {
+	XMLName xml.Name `xml:"http://schemas.xmlsoap.org/soap/envelope/ Envelope"`
+	Soap    *SoapBody
+}
+type SoapBody struct {
+	XMLName    xml.Name `xml:"http://schemas.xmlsoap.org/soap/envelope/ Body"`
+	ExternalIP *ExternalIPAddressResponse
+}
+
+type ExternalIPAddressResponse struct {
+	XMLName   xml.Name `xml:"GetExternalIPAddressResponse"`
+	IPAddress string   `xml:"NewExternalIPAddress"`
+}
+
+type ExternalIPAddress struct {
+	XMLName xml.Name `xml:"NewExternalIPAddress"`
+	IP      string
+}
+
+type Service struct {
+	ServiceType string `xml:"serviceType"`
+	ControlURL  string `xml:"controlURL"`
+}
+
+type DeviceList struct {
+	Device []Device `xml:"device"`
+}
+
+type ServiceList struct {
+	Service []Service `xml:"service"`
+}
+
+type Device struct {
+	XMLName     xml.Name    `xml:"device"`
+	DeviceType  string      `xml:"deviceType"`
+	DeviceList  DeviceList  `xml:"deviceList"`
+	ServiceList ServiceList `xml:"serviceList"`
+}
+
+type Root struct {
+	Device Device
+}
+
+func getChildDevice(d *Device, deviceType string) *Device {
+	dl := d.DeviceList.Device
+	for i := 0; i < len(dl); i++ {
+		if strings.Contains(dl[i].DeviceType, deviceType) {
+			return &dl[i]
+		}
+	}
+	return nil
+}
+
+func getChildService(d *Device, serviceType string) *Service {
+	sl := d.ServiceList.Service
+	for i := 0; i < len(sl); i++ {
+		if strings.Contains(sl[i].ServiceType, serviceType) {
+			return &sl[i]
+		}
+	}
+	return nil
+}
+
+func localIPv4() (net.IP, error) {
+	tt, err := net.Interfaces()
+	if err != nil {
+		return nil, err
+	}
+	for _, t := range tt {
+		aa, err := t.Addrs()
+		if err != nil {
+			return nil, err
+		}
+		for _, a := range aa {
+			ipnet, ok := a.(*net.IPNet)
+			if !ok {
+				continue
+			}
+			v4 := ipnet.IP.To4()
+			if v4 == nil || v4[0] == 127 { // loopback address
+				continue
+			}
+			return v4, nil
+		}
+	}
+	return nil, errors.New("cannot find local IP address")
+}
+
+func getServiceURL(rootURL string) (url, urnDomain string, err error) {
+	r, err := http.Get(rootURL)
+	if err != nil {
+		return
+	}
+	defer r.Body.Close()
+	if r.StatusCode >= 400 {
+		err = errors.New(r.Status)
+		return
+	}
+	var root Root
+	err = xml.NewDecoder(r.Body).Decode(&root)
+	if err != nil {
+		return
+	}
+	a := &root.Device
+	if !strings.Contains(a.DeviceType, "InternetGatewayDevice:1") {
+		err = errors.New("no InternetGatewayDevice")
+		return
+	}
+	b := getChildDevice(a, "WANDevice:1")
+	if b == nil {
+		err = errors.New("no WANDevice")
+		return
+	}
+	c := getChildDevice(b, "WANConnectionDevice:1")
+	if c == nil {
+		err = errors.New("no WANConnectionDevice")
+		return
+	}
+	d := getChildService(c, "WANIPConnection:1")
+	if d == nil {
+		// Some routers don't follow the UPnP spec, and put WanIPConnection under WanDevice,
+		// instead of under WanConnectionDevice
+		d = getChildService(b, "WANIPConnection:1")
+
+		if d == nil {
+			err = errors.New("no WANIPConnection")
+			return
+		}
+	}
+	// Extract the domain name, which isn't always 'schemas-upnp-org'
+	urnDomain = strings.Split(d.ServiceType, ":")[1]
+	url = combineURL(rootURL, d.ControlURL)
+	return
+}
+
+func combineURL(rootURL, subURL string) string {
+	protocolEnd := "://"
+	protoEndIndex := strings.Index(rootURL, protocolEnd)
+	a := rootURL[protoEndIndex+len(protocolEnd):]
+	rootIndex := strings.Index(a, "/")
+	return rootURL[0:protoEndIndex+len(protocolEnd)+rootIndex] + subURL
+}
+
+func soapRequest(url, function, message, domain string) (r *http.Response, err error) {
+	fullMessage := "<?xml version=\"1.0\" ?>" +
+		"<s:Envelope xmlns:s=\"http://schemas.xmlsoap.org/soap/envelope/\" s:encodingStyle=\"http://schemas.xmlsoap.org/soap/encoding/\">\r\n" +
+		"<s:Body>" + message + "</s:Body></s:Envelope>"
+
+	req, err := http.NewRequest("POST", url, strings.NewReader(fullMessage))
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("Content-Type", "text/xml ; charset=\"utf-8\"")
+	req.Header.Set("User-Agent", "Darwin/10.0.0, UPnP/1.0, MiniUPnPc/1.3")
+	//req.Header.Set("Transfer-Encoding", "chunked")
+	req.Header.Set("SOAPAction", "\"urn:"+domain+":service:WANIPConnection:1#"+function+"\"")
+	req.Header.Set("Connection", "Close")
+	req.Header.Set("Cache-Control", "no-cache")
+	req.Header.Set("Pragma", "no-cache")
+
+	// log.Stderr("soapRequest ", req)
+
+	r, err = http.DefaultClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	/*if r.Body != nil {
+		defer r.Body.Close()
+	}*/
+
+	if r.StatusCode >= 400 {
+		// log.Stderr(function, r.StatusCode)
+		err = errors.New("Error " + strconv.Itoa(r.StatusCode) + " for " + function)
+		r = nil
+		return
+	}
+	return
+}
+
+type statusInfo struct {
+	externalIpAddress string
+}
+
+func (n *UPnPNAT) getExternalIPAddress() (info statusInfo, err error) {
+
+	message := "<u:GetExternalIPAddress xmlns:u=\"urn:" + n.urnDomain + ":service:WANIPConnection:1\">\r\n" +
+		"</u:GetExternalIPAddress>"
+
+	var response *http.Response
+	response, err = soapRequest(n.serviceURL, "GetExternalIPAddress", message, n.urnDomain)
+	if response != nil {
+		defer response.Body.Close()
+	}
+	if err != nil {
+		return
+	}
+	var envelope Envelope
+	data, err := io.ReadAll(response.Body)
+	reader := bytes.NewReader(data)
+	xml.NewDecoder(reader).Decode(&envelope)
+
+	info = statusInfo{envelope.Soap.ExternalIP.IPAddress}
+
+	if err != nil {
+		return
+	}
+
+	return
+}
+
+func (n *UPnPNAT) GetExternalAddress() (addr net.IP, err error) {
+	info, err := n.getExternalIPAddress()
+	if err != nil {
+		return
+	}
+	addr = net.ParseIP(info.externalIpAddress)
+	return
+}
+
+func (n *UPnPNAT) AddPortMapping(protocol string, externalPort, internalPort int, description string, timeout int) (mappedExternalPort int, err error) {
+	// A single concatenation would break ARM compilation.
+	message := "<u:AddPortMapping xmlns:u=\"urn:" + n.urnDomain + ":service:WANIPConnection:1\">\r\n" +
+		"<NewRemoteHost></NewRemoteHost><NewExternalPort>" + strconv.Itoa(externalPort)
+	message += "</NewExternalPort><NewProtocol>" + protocol + "</NewProtocol>"
+	message += "<NewInternalPort>" + strconv.Itoa(internalPort) + "</NewInternalPort>" +
+		"<NewInternalClient>" + n.ourIP + "</NewInternalClient>" +
+		"<NewEnabled>1</NewEnabled><NewPortMappingDescription>"
+	message += description +
+		"</NewPortMappingDescription><NewLeaseDuration>" + strconv.Itoa(timeout) +
+		"</NewLeaseDuration></u:AddPortMapping>"
+
+	var response *http.Response
+	response, err = soapRequest(n.serviceURL, "AddPortMapping", message, n.urnDomain)
+	if response != nil {
+		defer response.Body.Close()
+	}
+	if err != nil {
+		return
+	}
+
+	// TODO: check response to see if the port was forwarded
+	// log.Println(message, response)
+	mappedExternalPort = externalPort
+	_ = response
+	return
+}
+
+func (n *UPnPNAT) DeletePortMapping(protocol string, externalPort, internalPort int) (err error) {
+
+	message := "<u:DeletePortMapping xmlns:u=\"urn:" + n.urnDomain + ":service:WANIPConnection:1\">\r\n" +
+		"<NewRemoteHost></NewRemoteHost><NewExternalPort>" + strconv.Itoa(externalPort) +
+		"</NewExternalPort><NewProtocol>" + protocol + "</NewProtocol>" +
+		"</u:DeletePortMapping>"
+
+	var response *http.Response
+	response, err = soapRequest(n.serviceURL, "DeletePortMapping", message, n.urnDomain)
+	if response != nil {
+		defer response.Body.Close()
+	}
+	if err != nil {
+		return
+	}
+
+	// TODO: check response to see if the port was deleted
+	// log.Println(message, response)
+	_ = response
+	return
+}