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receiver.go
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receiver.go
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package sacn
import (
"fmt"
"log"
"net"
"time"
"errors"
"golang.org/x/net/ipv4"
"github.com/libp2p/go-reuseport"
"gitlab.com/patopest/go-sacn/packet"
)
type PacketCallbackFunc func(p packet.SACNPacket, source string)
type TerminationCallbackFunc func(universe uint16)
type Receiver struct {
conn *ipv4.PacketConn
itf *net.Interface
stop chan bool
lastPackets map[uint16]networkPacket
streamTerminated map[uint16]bool
packetCallbacks map[packet.SACNPacketType]PacketCallbackFunc
terminationCallback TerminationCallbackFunc
}
type networkPacket struct {
ts time.Time
packet packet.SACNPacket
// source net.UDPAddr
}
func NewReceiver(itf *net.Interface) *Receiver {
r := &Receiver{}
addr := fmt.Sprintf(":%d", SACN_PORT)
listener, err := reuseport.ListenPacket("udp4", addr)
if err != nil {
log.Panicln(err)
}
udpConn := listener.(*net.UDPConn)
r.conn = ipv4.NewPacketConn(udpConn)
r.itf = itf
r.lastPackets = make(map[uint16]networkPacket)
r.streamTerminated = make(map[uint16]bool)
r.packetCallbacks = make(map[packet.SACNPacketType]PacketCallbackFunc)
return r
}
func (r *Receiver) Start() {
r.stop = make(chan bool)
go r.recvLoop()
}
func (r *Receiver) Stop() {
close(r.stop)
}
func (r *Receiver) JoinUniverse(universe uint16) error {
if universe == 0 || (universe > 64000 && universe != DISCOVERY_UNIVERSE) { // Section 9.1.1 of spec document
return errors.New(fmt.Sprintf("Invalid universe number: %d\n", universe))
}
err := r.conn.JoinGroup(r.itf, universeToAddress(universe))
if err != nil {
return errors.New(fmt.Sprintf("Could not join multicast group for universe %v: %v", universe, err))
}
return nil
}
func (r *Receiver) LeaveUniverse(universe uint16) error {
err := r.conn.LeaveGroup(r.itf, universeToAddress(universe))
if err != nil {
return errors.New(fmt.Sprintf("Could not leave multicast group for universe %v: %v", universe, err))
}
return nil
}
func (r *Receiver) RegisterPacketCallback(packetType packet.SACNPacketType, callback PacketCallbackFunc) {
r.packetCallbacks[packetType] = callback
}
func (r *Receiver) RegisterTerminationCallback(callback TerminationCallbackFunc) {
r.terminationCallback = callback
}
func (r *Receiver) recvLoop() {
defer r.conn.Close()
for {
select {
case <-r.stop:
return
default:
buf := make([]byte, 1144) // 1144 is max packet size (full DiscoveryPacket)
err := r.conn.SetDeadline(time.Now().Add(time.Millisecond * NETWORK_DATA_LOSS_TIMEOUT))
if err != nil {
log.Panic(fmt.Sprintf("Could not set deadline on socket: %v", err))
}
n, _, addr, _ := r.conn.ReadFrom(buf)
if addr == nil { // timeout
r.checkTimeouts()
continue
}
source := addr.(*net.UDPAddr)
// fmt.Printf("Received %d bytes from %s\n", n, source.String())
var p packet.SACNPacket
p, err = packet.Unmarshal(buf[:n])
if err != nil {
continue
}
r.handlePacket(p, source.IP.String())
}
}
}
func (r *Receiver) handlePacket(p packet.SACNPacket, source string) {
r.checkTimeouts()
packetType := p.GetType()
switch packetType {
case packet.PacketTypeData:
d, _ := p.(*packet.DataPacket)
r.storeLastPacket(d.Universe, d)
if (d.Options & 1 << 6) > 0 { // Bit 6: Stream Terminated
r.terminateUniverse(d.Universe)
return
}
if d.SyncAddress > 0 {
_, ok := r.streamTerminated[d.SyncAddress]
if !ok { // only join sync universe if not already
r.JoinUniverse(d.SyncAddress)
}
}
case packet.PacketTypeSync:
s, _ := p.(*packet.SyncPacket)
r.storeLastPacket(s.SyncAddress, s)
default:
/* code */
}
callback := r.packetCallbacks[packetType]
if callback != nil {
go callback(p, source)
}
}
func (r *Receiver) storeLastPacket(universe uint16, p packet.SACNPacket) {
r.lastPackets[universe] = networkPacket{
ts: time.Now(),
packet: p,
}
r.streamTerminated[universe] = false
}
func (r *Receiver) checkTimeouts() {
for universe, last := range r.lastPackets {
if time.Since(last.ts) > time.Millisecond*NETWORK_DATA_LOSS_TIMEOUT {
r.terminateUniverse(universe)
}
}
}
func (r *Receiver) terminateUniverse(universe uint16) {
if r.terminationCallback != nil && !r.streamTerminated[universe] {
go r.terminationCallback(universe)
r.streamTerminated[universe] = true
}
}