split nodes.go into focused files and refactor Update function

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

multicast.go

@@ -0,0 +1,177 @@
+package tendrils
+
+import (
+	"fmt"
+	"net"
+	"time"
+)
+
+type MulticastGroup struct {
+	IP net.IP
+}
+
+type MulticastMembership struct {
+	Node     *Node
+	LastSeen time.Time
+}
+
+type MulticastGroupMembers struct {
+	Group   *MulticastGroup
+	Members map[string]*MulticastMembership // source IP -> membership
+}
+
+func (g *MulticastGroup) Name() string {
+	ip := g.IP.To4()
+	if ip == nil {
+		return g.IP.String()
+	}
+
+	switch g.IP.String() {
+	case "224.0.0.251":
+		return "mdns"
+	case "224.0.1.129":
+		return "ptp"
+	case "224.0.1.130":
+		return "ptp-announce"
+	case "224.0.1.131":
+		return "ptp-sync"
+	case "224.0.1.132":
+		return "ptp-delay"
+	case "224.2.127.254":
+		return "sap"
+	case "239.255.254.253":
+		return "shure-slp"
+	case "239.255.255.250":
+		return "ssdp"
+	case "239.255.255.253":
+		return "slp"
+	case "239.255.255.255":
+		return "admin-scoped-broadcast"
+	}
+
+	// sACN (239.255.x.x, universes 1-63999)
+	if ip[0] == 239 && ip[1] == 255 {
+		universe := int(ip[2])*256 + int(ip[3])
+		if universe >= 1 && universe <= 63999 {
+			return fmt.Sprintf("sacn:%d", universe)
+		}
+	}
+
+	// Dante audio multicast (239.69-71.x.x)
+	if ip[0] == 239 && ip[1] >= 69 && ip[1] <= 71 {
+		flowID := (int(ip[1]-69) << 16) | (int(ip[2]) << 8) | int(ip[3])
+		return fmt.Sprintf("dante-mcast:%d", flowID)
+	}
+
+	// Dante AV multicast (239.253.x.x)
+	if ip[0] == 239 && ip[1] == 253 {
+		flowID := (int(ip[2]) << 8) | int(ip[3])
+		return fmt.Sprintf("dante-av:%d", flowID)
+	}
+
+	return g.IP.String()
+}
+
+func (g *MulticastGroup) IsDante() bool {
+	ip := g.IP.To4()
+	if ip == nil {
+		return false
+	}
+	if ip[0] == 239 && ip[1] >= 69 && ip[1] <= 71 {
+		return true
+	}
+	if ip[0] == 239 && ip[1] == 253 {
+		return true
+	}
+	return false
+}
+
+func (n *Nodes) UpdateMulticastMembership(sourceIP, groupIP net.IP) {
+	n.mu.Lock()
+	defer n.mu.Unlock()
+
+	node := n.getNodeByIPLocked(sourceIP)
+
+	groupKey := groupIP.String()
+	sourceKey := sourceIP.String()
+
+	gm := n.multicastGroups[groupKey]
+	if gm == nil {
+		gm = &MulticastGroupMembers{
+			Group:   &MulticastGroup{IP: groupIP},
+			Members: map[string]*MulticastMembership{},
+		}
+		n.multicastGroups[groupKey] = gm
+	}
+
+	gm.Members[sourceKey] = &MulticastMembership{
+		Node:     node,
+		LastSeen: time.Now(),
+	}
+}
+
+func (n *Nodes) RemoveMulticastMembership(sourceIP, groupIP net.IP) {
+	n.mu.Lock()
+	defer n.mu.Unlock()
+
+	groupKey := groupIP.String()
+	sourceKey := sourceIP.String()
+
+	if gm := n.multicastGroups[groupKey]; gm != nil {
+		delete(gm.Members, sourceKey)
+		if len(gm.Members) == 0 {
+			delete(n.multicastGroups, groupKey)
+		}
+	}
+}
+
+func (n *Nodes) GetDanteMulticastGroups(deviceIP net.IP) []net.IP {
+	n.mu.RLock()
+	defer n.mu.RUnlock()
+
+	deviceKey := deviceIP.String()
+	var groups []net.IP
+
+	for _, gm := range n.multicastGroups {
+		if !gm.Group.IsDante() {
+			continue
+		}
+		if _, exists := gm.Members[deviceKey]; exists {
+			groups = append(groups, gm.Group.IP)
+		}
+	}
+	return groups
+}
+
+func (n *Nodes) GetMulticastGroupMembers(groupIP net.IP) []*Node {
+	n.mu.RLock()
+	defer n.mu.RUnlock()
+
+	groupKey := groupIP.String()
+	gm := n.multicastGroups[groupKey]
+	if gm == nil {
+		return nil
+	}
+
+	var members []*Node
+	for _, membership := range gm.Members {
+		if membership.Node != nil {
+			members = append(members, membership.Node)
+		}
+	}
+	return members
+}
+
+func (n *Nodes) expireMulticastMemberships() {
+	expireTime := time.Now().Add(-5 * time.Minute)
+	for groupKey, gm := range n.multicastGroups {
+		for sourceKey, membership := range gm.Members {
+			if membership.LastSeen.Before(expireTime) {
+				delete(gm.Members, sourceKey)
+			}
+		}
+		if len(gm.Members) == 0 {
+			delete(n.multicastGroups, groupKey)
+		}
+	}
+}