Initial sACN library with protocol, sender, receiver, and discovery

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

sender.go

@@ -0,0 +1,145 @@
+package sacn
+
+import (
+	"crypto/rand"
+	"net"
+	"sort"
+	"sync"
+	"time"
+
+	"golang.org/x/net/ipv4"
+)
+
+type Sender struct {
+	conn       *net.UDPConn
+	sourceName string
+	cid        [16]byte
+	sequences  map[uint16]uint8
+	seqMu      sync.Mutex
+	universes  map[uint16]bool
+	done       chan struct{}
+}
+
+func NewSender(sourceName string, ifaceName string) (*Sender, error) {
+	conn, err := net.ListenUDP("udp4", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		return nil, err
+	}
+
+	if ifaceName != "" {
+		iface, err := net.InterfaceByName(ifaceName)
+		if err != nil {
+			conn.Close()
+			return nil, err
+		}
+		p := ipv4.NewPacketConn(conn)
+		if err := p.SetMulticastInterface(iface); err != nil {
+			conn.Close()
+			return nil, err
+		}
+	}
+
+	var cid [16]byte
+	rand.Read(cid[:])
+
+	return &Sender{
+		conn:       conn,
+		sourceName: sourceName,
+		cid:        cid,
+		sequences:  map[uint16]uint8{},
+		universes:  map[uint16]bool{},
+		done:       make(chan struct{}),
+	}, nil
+}
+
+func (s *Sender) CID() [16]byte {
+	return s.cid
+}
+
+func (s *Sender) SendDMX(universe uint16, data []byte) error {
+	s.seqMu.Lock()
+	seq := s.sequences[universe]
+	s.sequences[universe] = seq + 1
+	s.seqMu.Unlock()
+
+	pkt := BuildDataPacket(universe, seq, s.sourceName, s.cid, data)
+	addr := MulticastAddr(universe)
+
+	_, err := s.conn.WriteToUDP(pkt, addr)
+	return err
+}
+
+func (s *Sender) SendDMXUnicast(addr *net.UDPAddr, universe uint16, data []byte) error {
+	s.seqMu.Lock()
+	seq := s.sequences[universe]
+	s.sequences[universe] = seq + 1
+	s.seqMu.Unlock()
+
+	pkt := BuildDataPacket(universe, seq, s.sourceName, s.cid, data)
+
+	_, err := s.conn.WriteToUDP(pkt, addr)
+	return err
+}
+
+func (s *Sender) RegisterUniverse(universe uint16) {
+	s.seqMu.Lock()
+	s.universes[universe] = true
+	s.seqMu.Unlock()
+}
+
+func (s *Sender) StartDiscovery() {
+	go s.discoveryLoop()
+}
+
+func (s *Sender) Close() error {
+	select {
+	case <-s.done:
+	default:
+		close(s.done)
+	}
+	return s.conn.Close()
+}
+
+func (s *Sender) discoveryLoop() {
+	ticker := time.NewTicker(10 * time.Second)
+	defer ticker.Stop()
+
+	s.sendDiscovery()
+
+	for {
+		select {
+		case <-s.done:
+			return
+		case <-ticker.C:
+			s.sendDiscovery()
+		}
+	}
+}
+
+func (s *Sender) sendDiscovery() {
+	s.seqMu.Lock()
+	universes := make([]uint16, 0, len(s.universes))
+	for u := range s.universes {
+		universes = append(universes, u)
+	}
+	s.seqMu.Unlock()
+
+	if len(universes) == 0 {
+		return
+	}
+
+	sort.Slice(universes, func(i, j int) bool { return universes[i] < universes[j] })
+
+	const maxPerPage = 512
+	totalPages := (len(universes) + maxPerPage - 1) / maxPerPage
+
+	for page := 0; page < totalPages; page++ {
+		start := page * maxPerPage
+		end := start + maxPerPage
+		if end > len(universes) {
+			end = len(universes)
+		}
+		pkt := BuildDiscoveryPacket(s.sourceName, s.cid, uint8(page), uint8(totalPages-1), universes[start:end])
+		s.conn.WriteToUDP(pkt, DiscoveryAddr)
+	}
+}