🎉 live server seems to be working now

third_party/sendspin-go/pkg/discovery/mdns.go

@@ -0,0 +1,169 @@
+// ABOUTME: mDNS service discovery for Sendspin Protocol
+// ABOUTME: Handles both advertisement (server-initiated) and browsing (client-initiated)
+package discovery
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"log"
+	"net"
+
+	"github.com/hashicorp/mdns"
+)
+
+// silentLogger discards hashicorp/mdns internal logs
+var silentLogger = log.New(io.Discard, "", 0)
+
+type Config struct {
+	ServiceName string
+	Port        int
+	ServerMode  bool // If true, advertise as _sendspin-server._tcp, otherwise _sendspin._tcp
+}
+
+type Manager struct {
+	config  Config
+	ctx     context.Context
+	cancel  context.CancelFunc
+	servers chan *ServerInfo
+}
+
+type ServerInfo struct {
+	Name string
+	Host string
+	Port int
+}
+
+func NewManager(config Config) *Manager {
+	ctx, cancel := context.WithCancel(context.Background())
+
+	return &Manager{
+		config:  config,
+		ctx:     ctx,
+		cancel:  cancel,
+		servers: make(chan *ServerInfo, 10),
+	}
+}
+
+func (m *Manager) Advertise() error {
+	ips, err := getLocalIPs()
+	if err != nil {
+		return fmt.Errorf("failed to get local IPs: %w", err)
+	}
+
+	serviceType := "_sendspin._tcp"
+	if m.config.ServerMode {
+		serviceType = "_sendspin-server._tcp"
+	}
+
+	service, err := mdns.NewMDNSService(
+		m.config.ServiceName,
+		serviceType,
+		"",
+		"",
+		m.config.Port,
+		ips,
+		[]string{"path=/sendspin"},
+	)
+	if err != nil {
+		return fmt.Errorf("failed to create service: %w", err)
+	}
+
+	server, err := mdns.NewServer(&mdns.Config{Zone: service, Logger: silentLogger})
+	if err != nil {
+		return fmt.Errorf("failed to create mdns server: %w", err)
+	}
+
+	log.Printf("Advertising mDNS service: %s on port %d (type: %s)", m.config.ServiceName, m.config.Port, serviceType)
+
+	go func() {
+		<-m.ctx.Done()
+		server.Shutdown()
+	}()
+
+	return nil
+}
+
+func (m *Manager) Browse() error {
+	go m.browseLoop()
+	return nil
+}
+
+func (m *Manager) browseLoop() {
+	for {
+		select {
+		case <-m.ctx.Done():
+			return
+		default:
+		}
+
+		entries := make(chan *mdns.ServiceEntry, 10)
+
+		go func() {
+			for entry := range entries {
+				server := &ServerInfo{
+					Name: entry.Name,
+					Host: entry.AddrV4.String(),
+					Port: entry.Port,
+				}
+
+				log.Printf("Discovered server: %s at %s:%d", server.Name, server.Host, server.Port)
+
+				select {
+				case m.servers <- server:
+				case <-m.ctx.Done():
+					return
+				}
+			}
+		}()
+
+		params := &mdns.QueryParam{
+			Service: "_sendspin-server._tcp",
+			Domain:  "local",
+			Timeout: 3,
+			Entries: entries,
+			Logger:  silentLogger,
+		}
+
+		mdns.Query(params)
+		close(entries)
+	}
+}
+
+func (m *Manager) Servers() <-chan *ServerInfo {
+	return m.servers
+}
+
+func (m *Manager) Stop() {
+	m.cancel()
+}
+
+func getLocalIPs() ([]net.IP, error) {
+	var ips []net.IP
+
+	ifaces, err := net.Interfaces()
+	if err != nil {
+		return nil, err
+	}
+
+	for _, iface := range ifaces {
+		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 {
+					ips = append(ips, ipnet.IP)
+				}
+			}
+		}
+	}
+
+	return ips, nil
+}