Initial Art-Net protocol library

This commit is contained in:
Ian Gulliver
2026-01-28 10:27:25 -08:00
commit e02ba0cd5e
6 changed files with 868 additions and 0 deletions

261
discovery.go Normal file
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package artnet
import (
"net"
"sync"
"time"
)
type Node struct {
IP net.IP
Port uint16
MAC net.HardwareAddr
ShortName string
LongName string
Inputs []Universe
Outputs []Universe
LastSeen time.Time
}
type Discovery struct {
sender *Sender
receiver *Receiver
nodes map[string]*Node
nodesMu sync.RWMutex
localIP [4]byte
localMAC [6]byte
broadcast net.IP
shortName string
longName string
inputUnivs []Universe
outputUnivs []Universe
pollTargets []*net.UDPAddr
done chan struct{}
onChange func(*Node)
}
func NewDiscovery(sender *Sender, shortName, longName string, inputUnivs, outputUnivs []Universe, pollTargets []*net.UDPAddr) *Discovery {
return &Discovery{
sender: sender,
nodes: map[string]*Node{},
shortName: shortName,
longName: longName,
inputUnivs: inputUnivs,
outputUnivs: outputUnivs,
pollTargets: pollTargets,
done: make(chan struct{}),
}
}
func (d *Discovery) Start() {
d.detectInterface()
go d.pollLoop()
}
func (d *Discovery) Stop() {
close(d.done)
}
func (d *Discovery) SetReceiver(r *Receiver) {
d.receiver = r
}
func (d *Discovery) SetOnChange(fn func(*Node)) {
d.onChange = fn
}
func (d *Discovery) pollLoop() {
d.sendPolls()
ticker := time.NewTicker(10 * time.Second)
defer ticker.Stop()
cleanupTicker := time.NewTicker(30 * time.Second)
defer cleanupTicker.Stop()
for {
select {
case <-d.done:
return
case <-ticker.C:
d.sendPolls()
case <-cleanupTicker.C:
d.cleanup()
}
}
}
func (d *Discovery) sendPolls() {
for _, target := range d.pollTargets {
d.sender.SendPoll(target)
}
}
func (d *Discovery) cleanup() {
d.nodesMu.Lock()
defer d.nodesMu.Unlock()
cutoff := time.Now().Add(-60 * time.Second)
for ip, node := range d.nodes {
if node.LastSeen.Before(cutoff) {
delete(d.nodes, ip)
}
}
}
func (d *Discovery) HandlePollReply(src *net.UDPAddr, pkt *PollReplyPacket) {
d.nodesMu.Lock()
defer d.nodesMu.Unlock()
ip := src.IP.String()
localIP := net.IP(d.localIP[:])
if src.IP.Equal(localIP) {
return
}
node, exists := d.nodes[ip]
if !exists {
node = &Node{
IP: src.IP,
Port: pkt.Port,
}
d.nodes[ip] = node
}
node.ShortName = pkt.GetShortName()
node.LongName = pkt.GetLongName()
node.MAC = pkt.MACAddr()
node.LastSeen = time.Now()
for _, u := range pkt.InputUniverses() {
if !containsUniverse(node.Inputs, u) {
node.Inputs = append(node.Inputs, u)
}
}
for _, u := range pkt.OutputUniverses() {
if !containsUniverse(node.Outputs, u) {
node.Outputs = append(node.Outputs, u)
}
}
if d.onChange != nil {
d.onChange(node)
}
}
func (d *Discovery) HandlePoll(src *net.UDPAddr) {
if d.receiver == nil {
return
}
dst := &net.UDPAddr{IP: d.broadcast, Port: Port}
d.sendPollReplies(dst, d.inputUnivs, true)
d.sendPollReplies(dst, d.outputUnivs, false)
}
func (d *Discovery) sendPollReplies(dst *net.UDPAddr, universes []Universe, isInput bool) {
groups := map[uint16][]Universe{}
for _, u := range universes {
key := uint16(u.Net())<<8 | uint16(u.SubNet())<<4
groups[key] = append(groups[key], u)
}
for _, univs := range groups {
for i := 0; i < len(univs); i += 4 {
end := i + 4
if end > len(univs) {
end = len(univs)
}
chunk := univs[i:end]
pkt := BuildPollReplyPacket(d.localIP, d.localMAC, d.shortName, d.longName, chunk, isInput)
d.receiver.SendTo(pkt, dst)
}
}
}
func (d *Discovery) GetNodesForUniverse(universe Universe) []*Node {
d.nodesMu.RLock()
defer d.nodesMu.RUnlock()
var result []*Node
for _, node := range d.nodes {
for _, u := range node.Outputs {
if u == universe {
result = append(result, node)
break
}
}
}
return result
}
func (d *Discovery) GetAllNodes() []*Node {
d.nodesMu.RLock()
defer d.nodesMu.RUnlock()
result := make([]*Node, 0, len(d.nodes))
for _, node := range d.nodes {
result = append(result, node)
}
return result
}
func (d *Discovery) SetLocalIP(ip net.IP) {
if ip4 := ip.To4(); ip4 != nil {
copy(d.localIP[:], ip4)
}
}
func (d *Discovery) detectInterface() {
d.broadcast = net.IPv4bcast
ifaces, err := net.Interfaces()
if err != nil {
return
}
for _, iface := range ifaces {
if iface.Flags&net.FlagLoopback != 0 || iface.Flags&net.FlagUp == 0 {
continue
}
addrs, err := iface.Addrs()
if err != nil {
continue
}
for _, addr := range addrs {
ipnet, ok := addr.(*net.IPNet)
if !ok {
continue
}
ip4 := ipnet.IP.To4()
if ip4 == nil {
continue
}
copy(d.localIP[:], ip4)
if len(iface.HardwareAddr) == 6 {
copy(d.localMAC[:], iface.HardwareAddr)
}
bcast := make(net.IP, 4)
for i := 0; i < 4; i++ {
bcast[i] = ip4[i] | ^ipnet.Mask[i]
}
d.broadcast = bcast
return
}
}
}
func containsUniverse(slice []Universe, val Universe) bool {
for _, v := range slice {
if v == val {
return true
}
}
return false
}

3
go.mod Normal file
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module github.com/gopatchy/artnet
go 1.25.6

104
poller.go Normal file
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package artnet
import (
"net"
"time"
)
type Poller struct {
sender *Sender
targets []*net.UDPAddr
interval time.Duration
done chan struct{}
}
func NewPoller(sender *Sender, targets []*net.UDPAddr, interval time.Duration) *Poller {
return &Poller{
sender: sender,
targets: targets,
interval: interval,
done: make(chan struct{}),
}
}
func NewBroadcastPoller(sender *Sender, interval time.Duration) *Poller {
return &Poller{
sender: sender,
targets: []*net.UDPAddr{{IP: net.IPv4bcast, Port: Port}},
interval: interval,
done: make(chan struct{}),
}
}
func (p *Poller) Start() {
go p.loop()
}
func (p *Poller) Stop() {
close(p.done)
}
func (p *Poller) Poll() {
for _, target := range p.targets {
p.sender.SendPoll(target)
}
}
func (p *Poller) loop() {
p.Poll()
ticker := time.NewTicker(p.interval)
defer ticker.Stop()
for {
select {
case <-p.done:
return
case <-ticker.C:
p.Poll()
}
}
}
func (p *Poller) SetTargets(targets []*net.UDPAddr) {
p.targets = targets
}
func (p *Poller) AddTarget(target *net.UDPAddr) {
p.targets = append(p.targets, target)
}
func BroadcastAddr() *net.UDPAddr {
return &net.UDPAddr{IP: net.IPv4bcast, Port: Port}
}
func UnicastAddr(ip net.IP) *net.UDPAddr {
return &net.UDPAddr{IP: ip, Port: Port}
}
func InterfaceBroadcast(iface net.Interface) *net.UDPAddr {
addrs, err := iface.Addrs()
if err != nil {
return BroadcastAddr()
}
for _, addr := range addrs {
ipnet, ok := addr.(*net.IPNet)
if !ok {
continue
}
ip4 := ipnet.IP.To4()
if ip4 == nil {
continue
}
bcast := make(net.IP, 4)
for i := 0; i < 4; i++ {
bcast[i] = ip4[i] | ^ipnet.Mask[i]
}
return &net.UDPAddr{IP: bcast, Port: Port}
}
return BroadcastAddr()
}

322
protocol.go Normal file
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package artnet
import (
"bytes"
"encoding/binary"
"errors"
"fmt"
"net"
"strings"
)
const (
Port = 6454
ProtocolVersion = 14
OpPoll uint16 = 0x2000
OpPollReply uint16 = 0x2100
OpDmx uint16 = 0x5000
OpSync uint16 = 0x5200
OpAddress uint16 = 0x6000
OpInput uint16 = 0x7000
OpTodData uint16 = 0x8100
OpTodControl uint16 = 0x8200
OpRdm uint16 = 0x8300
PortTypeOutput uint8 = 0x80
PortTypeInput uint8 = 0x40
GoodOutputDataTransmitted uint8 = 0x80
GoodInputDataReceived uint8 = 0x80
StyleNode uint8 = 0x00
StyleController uint8 = 0x01
StyleMedia uint8 = 0x02
StyleRoute uint8 = 0x03
StyleBackup uint8 = 0x04
StyleConfig uint8 = 0x05
StyleVisual uint8 = 0x06
)
var (
ID = [8]byte{'A', 'r', 't', '-', 'N', 'e', 't', 0x00}
ErrInvalidHeader = errors.New("invalid Art-Net header")
ErrPacketTooShort = errors.New("packet too short")
)
type Universe uint16
func NewUniverse(netVal, subnet, universe uint8) Universe {
return Universe((uint16(netVal&0x7F) << 8) | (uint16(subnet&0x0F) << 4) | uint16(universe&0x0F))
}
func (u Universe) Net() uint8 { return uint8((u >> 8) & 0x7F) }
func (u Universe) SubNet() uint8 { return uint8((u >> 4) & 0x0F) }
func (u Universe) Universe() uint8 { return uint8(u & 0x0F) }
func (u Universe) String() string { return fmt.Sprintf("%d.%d.%d", u.Net(), u.SubNet(), u.Universe()) }
type DMXPacket struct {
ProtocolVersion uint16
Sequence uint8
Physical uint8
Universe Universe
Length uint16
Data [512]byte
}
type PollPacket struct {
ProtocolVersion uint16
Flags uint8
DiagPriority uint8
}
type PollReplyPacket struct {
IPAddress [4]byte
Port uint16
VersionInfo uint16
NetSwitch uint8
SubSwitch uint8
OemHi uint8
Oem uint8
UbeaVersion uint8
Status1 uint8
EstaMan uint16
ShortName [18]byte
LongName [64]byte
NodeReport [64]byte
NumPortsHi uint8
NumPortsLo uint8
PortTypes [4]byte
GoodInput [4]byte
GoodOutput [4]byte
SwIn [4]byte
SwOut [4]byte
SwVideo uint8
SwMacro uint8
SwRemote uint8
Style uint8
MAC [6]byte
BindIP [4]byte
BindIndex uint8
Status2 uint8
}
func (p *PollReplyPacket) IP() net.IP {
return net.IPv4(p.IPAddress[0], p.IPAddress[1], p.IPAddress[2], p.IPAddress[3])
}
func (p *PollReplyPacket) MACAddr() net.HardwareAddr {
return net.HardwareAddr(p.MAC[:])
}
func (p *PollReplyPacket) GetShortName() string {
return strings.TrimRight(string(p.ShortName[:]), "\x00")
}
func (p *PollReplyPacket) GetLongName() string {
return strings.TrimRight(string(p.LongName[:]), "\x00")
}
func (p *PollReplyPacket) NumPorts() int {
n := int(p.NumPortsLo)
if n > 4 {
n = 4
}
return n
}
func (p *PollReplyPacket) InputUniverses() []Universe {
var result []Universe
for i := 0; i < p.NumPorts(); i++ {
if p.PortTypes[i]&PortTypeInput != 0 {
u := NewUniverse(p.NetSwitch, p.SubSwitch, p.SwIn[i])
result = append(result, u)
}
}
return result
}
func (p *PollReplyPacket) OutputUniverses() []Universe {
var result []Universe
for i := 0; i < p.NumPorts(); i++ {
if p.PortTypes[i]&PortTypeOutput != 0 {
u := NewUniverse(p.NetSwitch, p.SubSwitch, p.SwOut[i])
result = append(result, u)
}
}
return result
}
func ParsePacket(data []byte) (uint16, interface{}, error) {
if len(data) < 10 {
return 0, nil, ErrPacketTooShort
}
if !bytes.Equal(data[:8], ID[:]) {
return 0, nil, ErrInvalidHeader
}
opCode := binary.LittleEndian.Uint16(data[8:10])
switch opCode {
case OpDmx:
pkt, err := parseDMXPacket(data)
return opCode, pkt, err
case OpPoll:
pkt, err := parsePollPacket(data)
return opCode, pkt, err
case OpPollReply:
pkt, err := parsePollReplyPacket(data)
return opCode, pkt, err
default:
return opCode, nil, nil
}
}
func parseDMXPacket(data []byte) (*DMXPacket, error) {
if len(data) < 18 {
return nil, ErrPacketTooShort
}
pkt := &DMXPacket{
ProtocolVersion: binary.BigEndian.Uint16(data[10:12]),
Sequence: data[12],
Physical: data[13],
Universe: Universe(binary.LittleEndian.Uint16(data[14:16])),
Length: binary.BigEndian.Uint16(data[16:18]),
}
dataLen := int(pkt.Length)
if dataLen > 512 {
dataLen = 512
}
if len(data) >= 18+dataLen {
copy(pkt.Data[:], data[18:18+dataLen])
}
return pkt, nil
}
func parsePollPacket(data []byte) (*PollPacket, error) {
if len(data) < 14 {
return nil, ErrPacketTooShort
}
return &PollPacket{
ProtocolVersion: binary.BigEndian.Uint16(data[10:12]),
Flags: data[12],
DiagPriority: data[13],
}, nil
}
func parsePollReplyPacket(data []byte) (*PollReplyPacket, error) {
if len(data) < 207 {
return nil, ErrPacketTooShort
}
pkt := &PollReplyPacket{
Port: binary.LittleEndian.Uint16(data[14:16]),
VersionInfo: binary.BigEndian.Uint16(data[16:18]),
NetSwitch: data[18],
SubSwitch: data[19],
OemHi: data[20],
Oem: data[21],
UbeaVersion: data[22],
Status1: data[23],
EstaMan: binary.LittleEndian.Uint16(data[24:26]),
NumPortsHi: data[172],
NumPortsLo: data[173],
Style: data[200],
BindIndex: data[212],
Status2: data[213],
}
copy(pkt.IPAddress[:], data[10:14])
copy(pkt.ShortName[:], data[26:44])
copy(pkt.LongName[:], data[44:108])
copy(pkt.NodeReport[:], data[108:172])
copy(pkt.PortTypes[:], data[174:178])
copy(pkt.GoodInput[:], data[178:182])
copy(pkt.GoodOutput[:], data[182:186])
copy(pkt.SwIn[:], data[186:190])
copy(pkt.SwOut[:], data[190:194])
copy(pkt.MAC[:], data[201:207])
copy(pkt.BindIP[:], data[207:211])
return pkt, nil
}
func BuildDMXPacket(universe Universe, sequence uint8, data []byte) []byte {
dataLen := len(data)
if dataLen > 512 {
dataLen = 512
}
if dataLen%2 != 0 {
dataLen++
}
buf := make([]byte, 18+dataLen)
copy(buf[0:8], ID[:])
binary.LittleEndian.PutUint16(buf[8:10], OpDmx)
binary.BigEndian.PutUint16(buf[10:12], ProtocolVersion)
buf[12] = sequence
buf[13] = 0
binary.LittleEndian.PutUint16(buf[14:16], uint16(universe))
binary.BigEndian.PutUint16(buf[16:18], uint16(dataLen))
copy(buf[18:], data[:dataLen])
return buf
}
func BuildPollPacket() []byte {
buf := make([]byte, 14)
copy(buf[0:8], ID[:])
binary.LittleEndian.PutUint16(buf[8:10], OpPoll)
binary.BigEndian.PutUint16(buf[10:12], ProtocolVersion)
buf[12] = 0x00
buf[13] = 0x00
return buf
}
func BuildPollReplyPacket(ip [4]byte, mac [6]byte, shortName, longName string, universes []Universe, isInput bool) []byte {
buf := make([]byte, 240)
copy(buf[0:8], ID[:])
binary.LittleEndian.PutUint16(buf[8:10], OpPollReply)
copy(buf[10:14], ip[:])
binary.LittleEndian.PutUint16(buf[14:16], Port)
binary.BigEndian.PutUint16(buf[16:18], ProtocolVersion)
if len(universes) > 0 {
buf[18] = universes[0].Net()
buf[19] = universes[0].SubNet()
}
copy(buf[26:44], shortName)
copy(buf[44:108], longName)
numPorts := len(universes)
if numPorts > 4 {
numPorts = 4
}
buf[173] = byte(numPorts)
for i := 0; i < numPorts; i++ {
if isInput {
buf[174+i] = PortTypeInput
buf[178+i] = GoodInputDataReceived
buf[186+i] = universes[i].Universe()
} else {
buf[174+i] = PortTypeOutput
buf[182+i] = GoodOutputDataTransmitted
buf[190+i] = universes[i].Universe()
}
}
copy(buf[201:207], mac[:])
copy(buf[207:211], ip[:])
buf[211] = 1
buf[212] = 0x08
return buf
}

107
receiver.go Normal file
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package artnet
import (
"net"
"time"
)
type Handler interface {
HandleDMX(src *net.UDPAddr, pkt *DMXPacket)
HandlePoll(src *net.UDPAddr, pkt *PollPacket)
HandlePollReply(src *net.UDPAddr, pkt *PollReplyPacket)
}
type Receiver struct {
conn *net.UDPConn
handler Handler
done chan struct{}
}
func NewReceiver(addr *net.UDPAddr, handler Handler) (*Receiver, error) {
conn, err := net.ListenUDP("udp4", addr)
if err != nil {
return nil, err
}
return &Receiver{
conn: conn,
handler: handler,
done: make(chan struct{}),
}, nil
}
func NewDefaultReceiver(handler Handler) (*Receiver, error) {
return NewReceiver(&net.UDPAddr{Port: Port}, handler)
}
func (r *Receiver) Start() {
go r.loop()
}
func (r *Receiver) Stop() {
close(r.done)
r.conn.Close()
}
func (r *Receiver) Conn() *net.UDPConn {
return r.conn
}
func (r *Receiver) LocalAddr() net.Addr {
return r.conn.LocalAddr()
}
func (r *Receiver) SendTo(data []byte, addr *net.UDPAddr) error {
_, err := r.conn.WriteToUDP(data, addr)
return err
}
func (r *Receiver) loop() {
buf := make([]byte, 1024)
for {
select {
case <-r.done:
return
default:
}
r.conn.SetReadDeadline(time.Now().Add(1 * time.Second))
n, src, err := r.conn.ReadFromUDP(buf)
if err != nil {
if netErr, ok := err.(net.Error); ok && netErr.Timeout() {
continue
}
select {
case <-r.done:
return
default:
continue
}
}
r.handle(src, buf[:n])
}
}
func (r *Receiver) handle(src *net.UDPAddr, data []byte) {
opCode, pkt, err := ParsePacket(data)
if err != nil {
return
}
switch opCode {
case OpDmx:
if dmx, ok := pkt.(*DMXPacket); ok {
r.handler.HandleDMX(src, dmx)
}
case OpPoll:
if poll, ok := pkt.(*PollPacket); ok {
r.handler.HandlePoll(src, poll)
}
case OpPollReply:
if reply, ok := pkt.(*PollReplyPacket); ok {
r.handler.HandlePollReply(src, reply)
}
}
}

71
sender.go Normal file
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package artnet
import (
"net"
"sync"
)
type Sender struct {
conn *net.UDPConn
sequences map[Universe]uint8
seqMu sync.Mutex
}
func NewSender() (*Sender, error) {
conn, err := net.ListenUDP("udp4", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
if err != nil {
return nil, err
}
return &Sender{
conn: conn,
sequences: map[Universe]uint8{},
}, nil
}
func NewSenderFromConn(conn *net.UDPConn) *Sender {
return &Sender{
conn: conn,
sequences: map[Universe]uint8{},
}
}
func (s *Sender) SendDMX(addr *net.UDPAddr, universe Universe, data []byte) error {
s.seqMu.Lock()
seq := s.sequences[universe]
seq++
if seq == 0 {
seq = 1
}
s.sequences[universe] = seq
s.seqMu.Unlock()
pkt := BuildDMXPacket(universe, seq, data)
_, err := s.conn.WriteToUDP(pkt, addr)
return err
}
func (s *Sender) SendPoll(addr *net.UDPAddr) error {
pkt := BuildPollPacket()
_, err := s.conn.WriteToUDP(pkt, addr)
return err
}
func (s *Sender) SendPollReply(addr *net.UDPAddr, localIP [4]byte, localMAC [6]byte, shortName, longName string, universes []Universe, isInput bool) error {
pkt := BuildPollReplyPacket(localIP, localMAC, shortName, longName, universes, isInput)
_, err := s.conn.WriteToUDP(pkt, addr)
return err
}
func (s *Sender) SendRaw(addr *net.UDPAddr, data []byte) error {
_, err := s.conn.WriteToUDP(data, addr)
return err
}
func (s *Sender) Close() error {
return s.conn.Close()
}
func (s *Sender) LocalAddr() net.Addr {
return s.conn.LocalAddr()
}