Initial sACN library with protocol, sender, receiver, and discovery
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
This commit is contained in:
Ian Gulliver
255
protocol.go
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255
protocol.go
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@@ -0,0 +1,255 @@
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package sacn
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import (
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"encoding/binary"
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"errors"
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"net"
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"strings"
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)
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const (
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Port = 5568
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VectorRootE131Data = 0x00000004
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VectorRootE131Extended = 0x00000008
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VectorE131DataPacket = 0x00000002
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VectorE131Discovery = 0x00000002
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VectorDMPSetProperty = 0x02
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VectorUniverseDiscovery = 0x00000001
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)
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var (
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PacketIdentifier = [12]byte{
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0x41, 0x53, 0x43, 0x2d, 0x45, 0x31, 0x2e, 0x31, 0x37, 0x00, 0x00, 0x00,
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}
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DiscoveryAddr = &net.UDPAddr{
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IP: net.IPv4(239, 255, 250, 214),
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Port: Port,
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}
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ErrInvalidHeader = errors.New("invalid sACN header")
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ErrPacketTooShort = errors.New("packet too short")
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ErrInvalidVector = errors.New("invalid vector")
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)
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type DataPacket struct {
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CID [16]byte
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SourceName string
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Priority uint8
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Sequence uint8
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Universe uint16
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Data [512]byte
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DataLen int
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}
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type DiscoveryPacket struct {
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CID [16]byte
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SourceName string
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Page uint8
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LastPage uint8
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Universes []uint16
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}
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func MulticastAddr(universe uint16) *net.UDPAddr {
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return &net.UDPAddr{
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IP: net.IPv4(239, 255, byte(universe>>8), byte(universe&0xff)),
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Port: Port,
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}
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}
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func ParsePacket(data []byte) (interface{}, error) {
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if len(data) < 22 {
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return nil, ErrPacketTooShort
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}
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if data[4] != PacketIdentifier[0] || data[5] != PacketIdentifier[1] ||
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data[6] != PacketIdentifier[2] || data[7] != PacketIdentifier[3] {
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return nil, ErrInvalidHeader
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}
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rootVector := binary.BigEndian.Uint32(data[18:22])
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switch rootVector {
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case VectorRootE131Data:
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return parseDataPacket(data)
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case VectorRootE131Extended:
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return parseExtendedPacket(data)
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default:
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return nil, ErrInvalidVector
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}
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}
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func parseDataPacket(data []byte) (*DataPacket, error) {
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if len(data) < 126 {
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return nil, ErrPacketTooShort
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}
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framingVector := binary.BigEndian.Uint32(data[40:44])
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if framingVector != VectorE131DataPacket {
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return nil, ErrInvalidVector
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}
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if data[117] != VectorDMPSetProperty {
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return nil, ErrInvalidVector
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}
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propCount := binary.BigEndian.Uint16(data[123:125])
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if propCount < 1 {
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return nil, ErrPacketTooShort
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}
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dmxLen := int(propCount) - 1
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if dmxLen > 512 {
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dmxLen = 512
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}
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if len(data) < 126+dmxLen {
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return nil, ErrPacketTooShort
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}
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pkt := &DataPacket{
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SourceName: strings.TrimRight(string(data[44:108]), "\x00"),
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Priority: data[108],
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Sequence: data[111],
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Universe: binary.BigEndian.Uint16(data[113:115]),
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DataLen: dmxLen,
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}
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copy(pkt.CID[:], data[22:38])
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copy(pkt.Data[:], data[126:126+dmxLen])
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return pkt, nil
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}
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func parseExtendedPacket(data []byte) (interface{}, error) {
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if len(data) < 118 {
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return nil, ErrPacketTooShort
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}
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framingVector := binary.BigEndian.Uint32(data[40:44])
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if framingVector != VectorE131Discovery {
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return nil, ErrInvalidVector
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}
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if len(data) < 120 {
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return nil, ErrPacketTooShort
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}
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discoveryVector := binary.BigEndian.Uint32(data[114:118])
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if discoveryVector != VectorUniverseDiscovery {
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return nil, ErrInvalidVector
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}
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pkt := &DiscoveryPacket{
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SourceName: strings.TrimRight(string(data[44:108]), "\x00"),
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Page: data[118],
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LastPage: data[119],
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}
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copy(pkt.CID[:], data[22:38])
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universeCount := (len(data) - 120) / 2
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pkt.Universes = make([]uint16, 0, universeCount)
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for i := 0; i < universeCount; i++ {
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u := binary.BigEndian.Uint16(data[120+i*2 : 122+i*2])
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if u >= 1 && u <= 63999 {
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pkt.Universes = append(pkt.Universes, u)
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}
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}
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return pkt, nil
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}
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func BuildDataPacket(universe uint16, sequence uint8, sourceName string, cid [16]byte, data []byte) []byte {
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dataLen := len(data)
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if dataLen > 512 {
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dataLen = 512
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}
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pktLen := 126 + dataLen
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buf := make([]byte, pktLen)
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binary.BigEndian.PutUint16(buf[0:2], 0x0010)
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binary.BigEndian.PutUint16(buf[2:4], 0x0000)
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copy(buf[4:16], PacketIdentifier[:])
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rootLen := pktLen - 16
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binary.BigEndian.PutUint16(buf[16:18], 0x7000|uint16(rootLen))
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binary.BigEndian.PutUint32(buf[18:22], VectorRootE131Data)
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copy(buf[22:38], cid[:])
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framingLen := pktLen - 38
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binary.BigEndian.PutUint16(buf[38:40], 0x7000|uint16(framingLen))
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binary.BigEndian.PutUint32(buf[40:44], VectorE131DataPacket)
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copy(buf[44:108], sourceName)
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buf[108] = 100
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binary.BigEndian.PutUint16(buf[109:111], 0)
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buf[111] = sequence
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buf[112] = 0
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binary.BigEndian.PutUint16(buf[113:115], universe)
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dmpLen := 11 + dataLen
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binary.BigEndian.PutUint16(buf[115:117], 0x7000|uint16(dmpLen))
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buf[117] = VectorDMPSetProperty
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buf[118] = 0xa1
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binary.BigEndian.PutUint16(buf[119:121], 0)
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binary.BigEndian.PutUint16(buf[121:123], 1)
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binary.BigEndian.PutUint16(buf[123:125], uint16(dataLen+1))
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buf[125] = 0
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copy(buf[126:], data[:dataLen])
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return buf
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}
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func BuildDiscoveryPacket(sourceName string, cid [16]byte, page, lastPage uint8, universes []uint16) []byte {
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universeCount := len(universes)
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if universeCount > 512 {
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universeCount = 512
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}
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pktLen := 120 + universeCount*2
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buf := make([]byte, pktLen)
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binary.BigEndian.PutUint16(buf[0:2], 0x0010)
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binary.BigEndian.PutUint16(buf[2:4], 0x0000)
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copy(buf[4:16], PacketIdentifier[:])
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rootLen := pktLen - 16
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binary.BigEndian.PutUint16(buf[16:18], 0x7000|uint16(rootLen))
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binary.BigEndian.PutUint32(buf[18:22], VectorRootE131Extended)
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copy(buf[22:38], cid[:])
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framingLen := pktLen - 38
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binary.BigEndian.PutUint16(buf[38:40], 0x7000|uint16(framingLen))
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binary.BigEndian.PutUint32(buf[40:44], VectorE131Discovery)
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copy(buf[44:108], sourceName)
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binary.BigEndian.PutUint32(buf[108:112], 0)
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discoveryLen := pktLen - 112
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binary.BigEndian.PutUint16(buf[112:114], 0x7000|uint16(discoveryLen))
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binary.BigEndian.PutUint32(buf[114:118], VectorUniverseDiscovery)
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buf[118] = page
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buf[119] = lastPage
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for i := 0; i < universeCount; i++ {
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binary.BigEndian.PutUint16(buf[120+i*2:122+i*2], universes[i])
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}
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return buf
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}
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func FormatCID(cid [16]byte) string {
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return strings.ToLower(formatUUID(cid))
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}
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func formatUUID(b [16]byte) string {
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const hexChars = "0123456789ABCDEF"
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result := make([]byte, 36)
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idx := 0
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for i, v := range b {
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if i == 4 || i == 6 || i == 8 || i == 10 {
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result[idx] = '-'
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idx++
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}
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result[idx] = hexChars[v>>4]
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result[idx+1] = hexChars[v&0x0f]
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idx += 2
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}
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return string(result)
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}
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