wemo/wemodiscovery/scan.go

package wemodiscovery

import (
	"encoding/xml"
	"fmt"
	"net/http"
	"io/ioutil"
	"time"

	"github.com/fromkeith/gossdp"
	"git.lerch.org/lobo/wemo/logger"
)

var responses []gossdp.ResponseMessage

type belkinListener struct {
	// Response func(message gossdp.ResponseMessage)
}

func (l belkinListener) Response(message gossdp.ResponseMessage) {
	responses = append(responses, message)
}

// Scan detects Belkin devices on the network. The devices that are returned have
// limited information in the Scan field, to get more detailed information you will
// have to call Load() on the device
func Scan(dt DeviceType, waitTimeSeconds int) ([]*Device, error) {
	responses = []gossdp.ResponseMessage{}
	l := belkinListener{}

	c, err := gossdp.NewSsdpClientWithLogger(l, &logger.LeveledLogger{})
	if err != nil {
		return nil, fmt.Errorf("failed to start ssdp discovery client: %s", err)
	}

	defer c.Stop()
	go c.Start()
	err = c.ListenFor(string(dt))
	if err != nil {
		return nil, fmt.Errorf("discovery failed: %s", err)
	}

	time.Sleep(time.Duration(waitTimeSeconds) * time.Second)

	devices := make([]*Device, len(responses))
	for i, response := range responses {
		devices[i] = &Device{Scan: response}
	}
	return devices, nil
}

// Load fetches all of the device specific information and updates the calling struct. The timeout
// parameter specifies how long to wait to connect and get a response before giving up
func (d *Device) Load(timeout time.Duration) error {
	client := http.Client{Timeout: timeout}
	resp, err := client.Get(d.Scan.Location)
	if resp != nil {
		defer resp.Body.Close()
	}
	if err != nil {
		return fmt.Errorf("error fetching device info: %s", err)
	}
	b, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return fmt.Errorf("error reading response from device: %s", err)
	}

	var root root
	root.Device = d
	err = xml.Unmarshal(b, &root)
	if err != nil {
		return err
	}

	return nil
}