Add a command to display all SSDP discoveries on local network.

cmd/discoverall/discoverall.go

@@ -0,0 +1,38 @@
+// Example program to display all devices discovered on the local network.
+package main
+
+import (
+	"fmt"
+	"log"
+
+	"github.com/huin/goupnp"
+	"github.com/huin/goupnp/ssdp"
+)
+
+func main() {
+	if err := run(); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func run() error {
+	devices, err := goupnp.DiscoverDevices(ssdp.SSDPAll)
+	if err != nil {
+		return err
+	}
+	for _, device := range devices {
+		fmt.Printf("Location: %v\n", device.Location)
+		fmt.Printf("USN: %v\n", device.USN)
+		if device.Err != nil {
+			fmt.Printf("  Error: %v\n", device.Err)
+		} else {
+			fmt.Printf("  Root v%d.%d @ %s\n",
+				device.Root.SpecVersion.Major, device.Root.SpecVersion.Minor,
+				device.Root.URLBaseStr)
+			fmt.Printf("  Type: %s\n", device.Root.Device.DeviceType)
+			fmt.Printf("  Friendly name: %s\n", device.Root.Device.FriendlyName)
+			fmt.Printf("  Num devices: %d\n", len(device.Root.Device.Devices))
+		}
+	}
+	return nil
+}

goupnp.go

@@ -39,6 +39,9 @@ func (err ContextError) Error() string {
 
 // MaybeRootDevice contains either a RootDevice or an error.
 type MaybeRootDevice struct {
+	// Identifier of the device.
+	USN string
+
 	// Set iff Err == nil.
 	Root *RootDevice
 
@@ -71,6 +74,7 @@ func DiscoverDevices(searchTarget string) ([]MaybeRootDevice, error) {
 	results := make([]MaybeRootDevice, len(responses))
 	for i, response := range responses {
 		maybe := &results[i]
+		maybe.USN = response.Header.Get("USN")
 		loc, err := response.Location()
 		if err != nil {
 			maybe.Err = ContextError{"unexpected bad location from search", err}