Discovery of IGD vaguely in place. Start of parsing device schema.

LICENSE

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+Copyright (c) 2013, John Beisley <greatred@gmail.com>
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without modification,
+are permitted provided that the following conditions are met:
+
+* Redistributions of source code must retain the above copyright notice, this
+  list of conditions and the following disclaimer.
+
+* Redistributions in binary form must reproduce the above copyright notice, this
+  list of conditions and the following disclaimer in the documentation and/or
+  other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

goupnp.go

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+package goupnp
+
+import (
+	"encoding/xml"
+	"errors"
+	"fmt"
+	"log"
+	"io"
+	"os"
+	"net/http"
+	"net/url"
+)
+
+const (
+	ssdpUDP4Addr = "239.255.255.250:1900"
+
+	methodSearch = "M-SEARCH"
+	// Search Target for InternetGatewayDevice.
+	stIgd  = "urn:schemas-upnp-org:device:InternetGatewayDevice:1"
+	hdrMan = `"ssdp:discover"`
+)
+
+// DiscoverIGD attempts to find Internet Gateway Devices.
+//
+// TODO: Fix implementation to discover multiple. Currently it will find a
+// maximum of one.
+func DiscoverIGD() ([]IGD, error) {
+	hc := http.Client{
+		Transport: udpRoundTripper{},
+		CheckRedirect: func(r *http.Request, via []*http.Request) error {
+			return errors.New("goupnp: unexpected HTTP redirect")
+		},
+		Jar: nil,
+	}
+
+	request := http.Request{
+		Method: methodSearch,
+		// TODO: Support both IPv4 and IPv6.
+		Host: ssdpUDP4Addr,
+		URL:  &url.URL{Opaque: "*"},
+		Header: http.Header{
+			// Putting headers in here avoids them being title-cased.
+			// (The UPnP discovery protocol uses case-sensitive headers)
+			"HOST": []string{ssdpUDP4Addr},
+			"MX":   []string{"2"}, // TODO: Variable max wait time.
+			"MAN":  []string{hdrMan},
+			"ST":   []string{stIgd},
+		},
+	}
+
+	response, err := hc.Do(&request)
+	if err != nil {
+		return nil, err
+	}
+
+	// Any errors past this point are simply "no result found". We log the
+	// errors, but report no results. In a future version of this implementation,
+	// multiple *good* results can be returned.
+
+	if response.StatusCode != 200 {
+		log.Printf("goupnp: response code %d %q from UPnP discovery",
+			response.StatusCode, response.Status)
+		return nil, nil
+	}
+	if st := response.Header.Get("ST"); st != stIgd {
+		log.Printf("goupnp: got unexpected search target result %q", st)
+		return nil, nil
+	}
+
+	location, err := response.Location()
+	if err != nil {
+		log.Printf("goupnp: missing location in response")
+		return nil, nil
+	}
+
+	igd, err := requestIgd(location.String())
+	if err != nil {
+		log.Printf("goupnp: error requesting IGD: %v", err)
+		return nil, nil
+	}
+
+	return []IGD{igd}, nil
+}
+
+// IGD defines the interface for an Internet Gateway Device.
+type IGD interface {
+}
+
+type igd struct {
+	serviceUrl string
+}
+
+func requestIgd(serviceUrl string) (IGD, error) {
+	resp, err := http.Get(serviceUrl)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	decoder := xml.NewDecoder(io.TeeReader(resp.Body, os.Stdout))
+	decoder.DefaultSpace = deviceXmlNs
+	var root xmlRootDevice
+	if err = decoder.Decode(&root); err != nil {
+		return nil, err
+	}
+	log.Printf("%+v", root)
+
+	return igd{serviceUrl}, nil
+}
+
+func (device *igd) String() string {
+	return fmt.Sprintf("goupnp.IGD @ %s", device.serviceUrl)
+}

udproundtripper.go

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+package goupnp
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"net"
+	"net/http"
+	"time"
+)
+
+// TODO: RoundTripper is probably the wrong interface, as there could be
+// multiple responses to a request.
+
+type udpRoundTripper struct {
+	// If zero, defaults to 3 second deadline (a zero deadline makes no sense).
+	Deadline       time.Duration
+	MaxWaitSeconds int
+}
+
+func (urt udpRoundTripper) RoundTrip(r *http.Request) (*http.Response, error) {
+	conn, err := net.ListenPacket("udp", ":0")
+	if err != nil {
+		return nil, err
+	}
+	defer conn.Close()
+
+	var requestBuf bytes.Buffer
+	if err := r.Write(&requestBuf); err != nil {
+		return nil, err
+	}
+	destAddr, err := net.ResolveUDPAddr("udp", r.Host)
+	if err != nil {
+		return nil, err
+	}
+
+	deadline := urt.Deadline
+	if urt.Deadline == 0 {
+		deadline = 3 * time.Second
+	}
+
+	if err = conn.SetDeadline(time.Now().Add(deadline)); err != nil {
+		return nil, err
+	}
+
+	// Send request.
+	if n, err := conn.WriteTo(requestBuf.Bytes(), destAddr); err != nil {
+		return nil, err
+	} else if n < len(requestBuf.Bytes()) {
+		return nil, fmt.Errorf("goupnp: wrote %d bytes rather than full %d in request",
+			n, len(requestBuf.Bytes()))
+	}
+
+	// Await response.
+	responseBytes := make([]byte, 2048)
+	n, _, err := conn.ReadFrom(responseBytes)
+	if err != nil {
+		return nil, err
+	}
+	responseBytes = responseBytes[:n]
+
+	// Parse response.
+	response, err := http.ReadResponse(bufio.NewReader(bytes.NewBuffer(responseBytes)), r)
+	if err != nil {
+		return nil, err
+	}
+
+	return response, err
+}

xml.go

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+// This file contains XML structures for communicating with UPnP devices.
+
+package goupnp
+
+import (
+	"encoding/xml"
+)
+
+const (
+	deviceXmlNs = "urn:schemas-upnp-org:device-1-0"
+)
+
+type xmlRootDevice struct {
+	Name xml.Name `xml:"root`
+	SpecVersion xmlSpecVersion `xml:"specVersion"`
+	URLBase string `xml:"URLBase"`
+	Device xmlDevice `xml:"device"`
+}
+
+type xmlSpecVersion struct {
+	Major int32 `xml:"major"`
+	Minor int32 `xml:"minor"`
+}
+
+type xmlDevice struct {
+	DeviceType string `xml:"deviceType"`
+	FriendlyName string `xml:"friendlyName"`
+	Manufacturer string `xml:"manufacturer"`
+	ManufacturerURL string `xml:"manufacturerURL"`
+	ModelDescription string `xml:"modelDescription"`
+	ModelName string `xml:"modelName"`
+	ModelNumber string `xml:"modelNumber"`
+	ModelURL string `xml:"modelURL"`
+	SerialNumber string `xml:"serialNumber"`
+	UDN string `xml:"UDN"`
+	UPC string `xml:"UPC,omitempty"`
+	Icons []xmlIcon `xml:"iconList>icon,omitempty"`
+	Services []xmlService `xml:"serviceList>service,omitempty"`
+	Devices []xmlDevice `xml:"deviceList>device,omitempty"`
+
+	// Extra observed elements:
+	PresentationURL string `xml:"presentationURL"`
+}
+
+type xmlIcon struct {
+	Mimetype string `xml:"mimetype"`
+	Width int32 `xml:"width"`
+	Height int32 `xml:"height"`
+	Depth int32 `xml:"depth"`
+	URL string `xml:"url"`
+}
+
+type xmlService struct {
+	ServiceType string `xml:"serviceType"`
+	ServiceId string `xml:"serviceId"`
+	SCPDURL string `xml:"SCPDURL"`
+	ControlURL string `xml:"controlURL"`
+	EventSubURL string `xml:"eventSubURL"`
+}