(feat) Enhance device discovery for complex and mesh networks

README.md

@@ -344,3 +344,39 @@ $ go-chromecast tts '<speak>Hello<break time="500ms"/>world.</speak>' \
   --google-service-account=/path/to/service/account.json \
   --ssml
 ```
+
+### Enhanced Device Discovery (Experimental)
+
+**Broad Search** - For complex network topologies with multiple subnets or VLANs, the `--broad-search` flag enables comprehensive device discovery that combines mDNS discovery with targeted port scanning across detected network interfaces.
+
+```bash
+# Use broad search to find devices across multiple subnets
+$ go-chromecast ls --broad-search
+
+# Works with all commands that connect to devices
+$ go-chromecast status --broad-search
+$ go-chromecast load media.mp4 --broad-search
+$ go-chromecast ui --broad-search
+```
+
+**Multi-Subnet Scanning** - The `scan` command supports scanning specific subnets or auto-detecting all available subnets:
+
+```bash
+# Scan specific subnets
+$ go-chromecast scan --subnets 192.168.4.0/24,192.168.3.0/24
+
+# Scan all detected subnets
+$ go-chromecast scan --subnets *
+
+# Traditional single subnet scan (default behavior)
+$ go-chromecast scan --cidr 192.168.1.0/24
+```
+
+**When to use:**
+- Multiple VLANs or subnets in your network
+- Chromecast devices not appearing in device list
+- Network setups with WiFi isolation or complex routing
+- Corporate networks with segmented subnets
+- Chromecast Audio groups on different ports
+
+**Note:** Broad search is slower than standard discovery as it performs more comprehensive network scanning. The enhanced discovery automatically detects your network topology and finds devices that standard mDNS discovery might miss, including Chromecast groups on non-standard ports.

application/application.go

@@ -87,6 +87,7 @@ type App interface {
 	AddMessageFunc(f CastMessageFunc)
 	PlayedItems() map[string]PlayedItem
 	PlayableMediaType(filename string) bool
+	GetLocalIP() (string, error)
 }
 
 type Application struct {
@@ -241,6 +242,10 @@ func (a *Application) App() *cast.Application { return a.application }
 func (a *Application) Media() *cast.Media     { return a.media }
 func (a *Application) Volume() *cast.Volume   { return a.volumeReceiver }
 
+func (a *Application) GetLocalIP() (string, error) {
+	return a.getLocalIP()
+}
+
 func (a *Application) AddMessageFunc(f CastMessageFunc) {
 	a.messageMu.Lock()
 	defer a.messageMu.Unlock()

cmd/load-app.go

@@ -28,14 +28,14 @@ var loadAppCmd = &cobra.Command{
 the chromecast receiver app to be specified. An older list can be found 
 here https://gist.github.com/jloutsenhizer/8855258.
 `,
-	Run: func(cmd *cobra.Command, args []string) {
-		if len(args) != 2 {
-			exit("requires exactly two arguments")
-		}
-		app, err := castApplication(cmd, args)
-		if err != nil {
-			exit("unable to get cast application: %v", err)
-		}
+Run: func(cmd *cobra.Command, args []string) {
+	if len(args) != 2 {
+		exit("requires exactly two arguments")
+	}
+	app, err := castApplication(cmd, args)
+	if err != nil {
+		exit("unable to get cast application: %v", err)
+	}
 
 		// Optionally run a UI when playing this media:
 		runWithUI, _ := cmd.Flags().GetBool("with-ui")

cmd/localip.go

@@ -0,0 +1,81 @@
+package cmd
+
+import (
+	"fmt"
+	"net"
+
+	"github.com/spf13/cobra"
+)
+
+var localIPCmd = &cobra.Command{
+	Use:   "localip",
+	Short: "Print the local IP address used by go-chromecast",
+	Run: func(cmd *cobra.Command, args []string) {
+		ifaceName, _ := cmd.Flags().GetString("iface")
+		ip, err := detectLocalIP(ifaceName)
+		if err != nil {
+			exit("unable to determine local IP: %v", err)
+		}
+		fmt.Println(ip)
+	},
+}
+
+// detectLocalIP attempts to detect the local IP address based on the network interface
+func detectLocalIP(ifaceName string) (string, error) {
+	var iface *net.Interface
+	var err error
+
+	if ifaceName != "" {
+		iface, err = net.InterfaceByName(ifaceName)
+		if err != nil {
+			return "", err
+		}
+	}
+
+	if iface != nil {
+		// Use the specified interface
+		addrs, err := iface.Addrs()
+		if err != nil {
+			return "", err
+		}
+		for _, addr := range addrs {
+			if ipnet, ok := addr.(*net.IPNet); ok && !ipnet.IP.IsLoopback() {
+				if ipnet.IP.To4() != nil {
+					return ipnet.IP.String(), nil
+				}
+			}
+		}
+	} else {
+		// Try to find the default route interface
+		interfaces, err := net.Interfaces()
+		if err != nil {
+			return "", err
+		}
+
+		for _, iface := range interfaces {
+			if iface.Flags&net.FlagUp == 0 || iface.Flags&net.FlagLoopback != 0 {
+				continue
+			}
+
+			addrs, err := iface.Addrs()
+			if err != nil {
+				continue
+			}
+
+			for _, addr := range addrs {
+				if ipnet, ok := addr.(*net.IPNet); ok && !ipnet.IP.IsLoopback() {
+					if ipnet.IP.To4() != nil {
+						return ipnet.IP.String(), nil
+					}
+				}
+			}
+		}
+	}
+
+	return "", fmt.Errorf("could not detect local IP address")
+}
+
+func init() {
+	localIPCmd.Flags().String("iface", "", "network interface to use for detecting local IP (optional)")
+	rootCmd.AddCommand(localIPCmd)
+}

cmd/ls.go

@@ -16,10 +16,15 @@ package cmd
 
 import (
 	"context"
+	"fmt"
 	"net"
+	"sort"
+	"sync"
 	"time"
 
+	"github.com/seancfoley/ipaddress-go/ipaddr"
 	"github.com/spf13/cobra"
+	"github.com/vishen/go-chromecast/application"
 	castdns "github.com/vishen/go-chromecast/dns"
 )
 
@@ -30,28 +35,176 @@ var lsCmd = &cobra.Command{
 	Run: func(cmd *cobra.Command, args []string) {
 		ifaceName, _ := cmd.Flags().GetString("iface")
 		dnsTimeoutSeconds, _ := cmd.Flags().GetInt("dns-timeout")
+		broadSearch, _ := cmd.Flags().GetBool("broad-search")
+
 		var iface *net.Interface
 		var err error
 		if ifaceName != "" {
 			if iface, err = net.InterfaceByName(ifaceName); err != nil {
 				exit("unable to find interface %q: %v", ifaceName, err)
 			}
+		} else {
+			// If no interface was specified, try to auto-detect the best interface
+			if iface, err = detectBestInterface(); err != nil {
+				// If auto-detection fails, continue without interface (original behavior)
+				iface = nil
+			}
 		}
-		ctx, cancel := context.WithTimeout(context.Background(), time.Second*time.Duration(dnsTimeoutSeconds))
-		defer cancel()
-		castEntryChan, err := castdns.DiscoverCastDNSEntries(ctx, iface)
-		if err != nil {
-			exit("unable to discover chromecast devices: %v", err)
+
+		if broadSearch {
+			// Use hybrid approach: mDNS + port scanning
+			foundDevices := performBroadSearch(iface, dnsTimeoutSeconds)
+			if len(foundDevices) == 0 {
+				outputError("no cast devices found on network")
+			} else {
+				for i, device := range foundDevices {
+					outputInfo("%d) device=%q device_name=%q address=\"%s:%d\" uuid=%q", 
+						i+1, device.Device, device.DeviceName, device.AddrV4, device.Port, device.UUID)
+				}
+			}
+		} else {
+			// Use original mDNS-only approach
+			ctx, cancel := context.WithTimeout(context.Background(), time.Second*time.Duration(dnsTimeoutSeconds))
+			defer cancel()
+			castEntryChan, err := castdns.DiscoverCastDNSEntries(ctx, iface)
+			if err != nil {
+				exit("unable to discover chromecast devices: %v", err)
+			}
+			i := 1
+			for d := range castEntryChan {
+				outputInfo("%d) device=%q device_name=%q address=\"%s:%d\" uuid=%q", i, d.Device, d.DeviceName, d.AddrV4, d.Port, d.UUID)
+				i++
+			}
+			if i == 1 {
+				outputError("no cast devices found on network")
+			}
 		}
-		i := 1
+	},
+}
+
+// CastDevice represents a discovered Chromecast device
+type CastDevice struct {
+	Device     string
+	DeviceName string
+	AddrV4     string
+	Port       int
+	UUID       string
+}
+
+// performBroadSearch does a comprehensive search using both mDNS and port scanning
+func performBroadSearch(iface *net.Interface, dnsTimeoutSeconds int) []CastDevice {
+	var allDevices []CastDevice
+	deviceMap := make(map[string]CastDevice) // Use UUID as key to deduplicate
+
+	// First, try mDNS discovery
+	outputInfo("Performing mDNS discovery...")
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second*time.Duration(dnsTimeoutSeconds*3)) // Use 3x timeout for broad search
+	castEntryChan, err := castdns.DiscoverCastDNSEntries(ctx, iface)
+	if err == nil {
 		for d := range castEntryChan {
-			outputInfo("%d) device=%q device_name=%q address=\"%s:%d\" uuid=%q", i, d.Device, d.DeviceName, d.AddrV4, d.Port, d.UUID)
-			i++
+			device := CastDevice{
+				Device:     d.Device,
+				DeviceName: d.DeviceName,
+				AddrV4:     d.AddrV4.String(),
+				Port:       d.Port,
+				UUID:       d.UUID,
+			}
+			if device.UUID != "" {
+				deviceMap[device.UUID] = device
+			} else {
+				// If no UUID, use address:port as key
+				key := fmt.Sprintf("%s:%d", device.AddrV4, device.Port)
+				deviceMap[key] = device
+			}
 		}
-		if i == 1 {
-			outputError("no cast devices found on network")
+	}
+	cancel()
+
+	outputInfo("Found %d devices via mDNS, performing port scan to find additional devices...", len(deviceMap))
+
+	// Then, do a targeted port scan on the local subnet
+	if localSubnet, err := detectLocalSubnet(""); err == nil {
+		ipRange, err := ipaddr.NewIPAddressString(localSubnet).ToSequentialRange()
+		if err == nil {
+			// Use a smaller set of ports for ls to keep it reasonably fast
+			ports := []int{8009, 8008, 8443, 32236} // Common ports + known group port
+
+			var wg sync.WaitGroup
+			ipCh := make(chan *ipaddr.IPAddress, 100)
+
+			// Send IPs to scan
+			go func() {
+				it := ipRange.Iterator()
+				for it.HasNext() {
+					ip := it.Next()
+					ipCh <- ip
+				}
+				close(ipCh)
+			}()
+
+			// Scan IPs in parallel
+			for i := 0; i < 20; i++ { // Use fewer goroutines than scan command
+				wg.Add(1)
+				go func() {
+					defer wg.Done()
+					dialer := &net.Dialer{
+						Timeout: 300 * time.Millisecond,
+					}
+					for ip := range ipCh {
+						for _, port := range ports {
+							conn, err := dialer.Dial("tcp", fmt.Sprintf("%v:%d", ip, port))
+							if err != nil {
+								continue
+							}
+							conn.Close()
+
+							// Try to get device info
+							if info, err := application.GetInfo(ip.String()); err == nil {
+								device := CastDevice{
+									Device:     "Unknown Device",
+									DeviceName: info.Name,
+									AddrV4:     ip.String(),
+									Port:       port,
+									UUID:       "", // Port scan doesn't give us UUID
+								}
+
+								// Use address:port as key since we don't have UUID from port scan
+								key := fmt.Sprintf("%s:%d", device.AddrV4, device.Port)
+
+								// Only add if we haven't seen this device yet
+								if _, exists := deviceMap[key]; !exists {
+									// Also check if we have this device by name on a different port
+									found := false
+									for _, existing := range deviceMap {
+										if existing.DeviceName == device.DeviceName && existing.AddrV4 == device.AddrV4 {
+											found = true
+											break
+										}
+									}
+									if !found {
+										deviceMap[key] = device
+									}
+								}
+							}
+						}
+					}
+				}()
+			}
+			wg.Wait()
 		}
-	},
+	}
+
+	// Convert map to slice and sort
+	for _, device := range deviceMap {
+		allDevices = append(allDevices, device)
+	}
+
+	// Sort by device name for consistent output
+	sort.Slice(allDevices, func(i, j int) bool {
+		return allDevices[i].DeviceName < allDevices[j].DeviceName
+	})
+
+	return allDevices
 }
 
 func init() {

cmd/mute.go

@@ -23,7 +23,7 @@ var muteCmd = &cobra.Command{
 	Use:   "mute",
 	Short: "Mute the chromecast",
 	Run: func(cmd *cobra.Command, args []string) {
-		app, err := castApplication(cmd, args)
+ 		app, err := castApplication(cmd, args)
 		if err != nil {
 			exit("unable to get cast application: %v", err)
 		}

cmd/next.go

@@ -23,7 +23,7 @@ var nextCmd = &cobra.Command{
 	Use:   "next",
 	Short: "Play the next available media",
 	Run: func(cmd *cobra.Command, args []string) {
-		app, err := castApplication(cmd, args)
+ 		app, err := castApplication(cmd, args)
 		if err != nil {
 			exit("unable to get cast application: %v", err)
 		}

cmd/pause.go

@@ -23,7 +23,7 @@ var pauseCmd = &cobra.Command{
 	Use:   "pause",
 	Short: "Pause the currently playing media on the chromecast",
 	Run: func(cmd *cobra.Command, args []string) {
-		app, err := castApplication(cmd, args)
+ 		app, err := castApplication(cmd, args)
 		if err != nil {
 			exit("unable to get cast application: %v", err)
 		}