// from taipei-torrent // TODO: use syscalls to get actual ourIP. http://pastebin.com/9exZG4rh package peer // Just enough UPnP to be able to forward ports // import ( "bytes" "encoding/xml" "errors" "io/ioutil" "net" "net/http" "strconv" "strings" "time" ) type upnpNAT struct { serviceURL string ourIP string urnDomain string } // protocol is either "udp" or "tcp" type NAT interface { GetExternalAddress() (addr net.IP, err error) AddPortMapping(protocol string, externalPort, internalPort int, description string, timeout int) (mappedExternalPort int, err error) DeletePortMapping(protocol string, externalPort, internalPort int) (err error) } func Discover() (nat NAT, 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 n, _, err = socket.ReadFromUDP(answerBytes) for { n, _, err = socket.ReadFromUDP(answerBytes) if err != nil { break } answer := string(answerBytes[0:n]) if strings.Index(answer, st) < 0 { 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.Index(dl[i].DeviceType, deviceType) >= 0 { 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.Index(sl[i].ServiceType, serviceType) >= 0 { 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(string(r.StatusCode)) return } var root Root err = xml.NewDecoder(r.Body).Decode(&root) if err != nil { return } a := &root.Device if strings.Index(a.DeviceType, "InternetGatewayDevice:1") < 0 { 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 := "" + "\r\n" + "" + message + "" 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 := "\r\n" + "" 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 := ioutil.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 := "\r\n" + "" + strconv.Itoa(externalPort) message += "" + protocol + "" message += "" + strconv.Itoa(internalPort) + "" + "" + n.ourIP + "" + "1" message += description + "" + strconv.Itoa(timeout) + "" 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 := "\r\n" + "" + strconv.Itoa(externalPort) + "" + protocol + "" + "" 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 }