Changes to be committed:

modified:   cmd/pmomusic/main.go
	new file:   internal/netutils/ip_detect.go
	new file:   internal/netutils/list_all_ip.go
	modified:   internal/soap/soap.go
	modified:   internal/ssdp/responder.go
	modified:   internal/ssdp/ssdp.go
	modified:   internal/upnp/http.go
	new file:   internal/upnp/server.go
	new file:   internal/upnp/xml/AVTransport.xml
	new file:   internal/upnp/xml/ConnectionManager.xml
	new file:   internal/upnp/xml/RenderingControl.xml

internal/netutils/ip_detect.go

@@ -0,0 +1,92 @@
+package netutils
+
+import (
+	"errors"
+	"net"
+	"sort"
+	"strings"
+)
+
+// GuessLocalIP returns the best-guess local IP address usable for UPnP location,
+// in order of preference: eth0 > en* > wl* > any private, non-loopback IP.
+func GuessLocalIP() (string, error) {
+	ifaces, err := net.Interfaces()
+	if err != nil {
+		return "", err
+	}
+
+	type scoredIP struct {
+		ip    net.IP
+		score int
+	}
+
+	var candidates []scoredIP
+
+	for _, iface := range ifaces {
+		// Skip interfaces that are down or loopback
+		if iface.Flags&net.FlagUp == 0 || iface.Flags&net.FlagLoopback != 0 {
+			continue
+		}
+
+		addrs, err := iface.Addrs()
+		if err != nil {
+			continue
+		}
+
+		for _, addr := range addrs {
+			var ip net.IP
+
+			switch v := addr.(type) {
+			case *net.IPNet:
+				ip = v.IP
+			case *net.IPAddr:
+				ip = v.IP
+			}
+
+			// Skip non-IPv4 or non-private addresses
+			if ip == nil || ip.IsLoopback() || ip.To4() == nil || !isPrivateIPv4(ip) {
+				continue
+			}
+
+			score := scoreInterfaceName(iface.Name)
+			candidates = append(candidates, scoredIP{ip: ip, score: score})
+		}
+	}
+
+	if len(candidates) == 0 {
+		return "", errors.New("no suitable local IP found")
+	}
+
+	// Prefer interfaces with higher score
+	sort.SliceStable(candidates, func(i, j int) bool {
+		return candidates[i].score > candidates[j].score
+	})
+
+	return candidates[0].ip.String(), nil
+}
+
+func isPrivateIPv4(ip net.IP) bool {
+	private := []string{
+		"10.", "172.16.", "172.17.", "172.18.", "172.19.", "172.2", "192.168.",
+	}
+	ipStr := ip.String()
+	for _, p := range private {
+		if strings.HasPrefix(ipStr, p) {
+			return true
+		}
+	}
+	return false
+}
+
+func scoreInterfaceName(name string) int {
+	switch {
+	case name == "eth0":
+		return 100
+	case strings.HasPrefix(name, "en"):
+		return 80
+	case name == "wlan0" || strings.HasPrefix(name, "wl"):
+		return 60
+	default:
+		return 10
+	}
+}

internal/netutils/list_all_ip.go

@@ -0,0 +1,49 @@
+package netutils
+
+import (
+	"net"
+)
+
+// ListAllIPs returns a map of interface names to their associated IPv4 addresses.
+func ListAllIPs() map[string][]string {
+	result := make(map[string][]string)
+
+	ifaces, err := net.Interfaces()
+	if err != nil {
+		result["error"] = []string{err.Error()}
+		return result
+	}
+
+	for _, iface := range ifaces {
+		if iface.Flags&net.FlagUp == 0 {
+			continue // Ignore down interfaces
+		}
+
+		addrs, err := iface.Addrs()
+		if err != nil {
+			continue
+		}
+
+		var ips []string
+		for _, addr := range addrs {
+			var ip net.IP
+			switch v := addr.(type) {
+			case *net.IPNet:
+				ip = v.IP
+			case *net.IPAddr:
+				ip = v.IP
+			}
+
+			if ip == nil || ip.To4() == nil || ip.IsLoopback() {
+				continue
+			}
+			ips = append(ips, ip.String())
+		}
+
+		if len(ips) > 0 {
+			result[iface.Name] = ips
+		}
+	}
+
+	return result
+}