Bind send interface for sacn

main.go

@@ -34,6 +34,7 @@ func main() {
 	configPath := flag.String("config", "config.toml", "path to config file")
 	artnetListen := flag.String("artnet-listen", ":6454", "artnet listen address (empty to disable)")
 	artnetBroadcast := flag.String("artnet-broadcast", "auto", "artnet broadcast addresses (comma-separated, or 'auto')")
+	sacnInterface := flag.String("sacn-interface", "", "network interface for sACN multicast")
 	debug := flag.Bool("debug", false, "log incoming/outgoing dmx packets")
 	flag.Parse()
 
@@ -107,7 +108,7 @@ func main() {
 	defer artSender.Close()
 
 	// Create sACN sender
-	sacnSender, err := sacn.NewSender("artmap")
+	sacnSender, err := sacn.NewSender("artmap", *sacnInterface)
 	if err != nil {
 		log.Fatalf("sacn sender error: %v", err)
 	}

sacn/sender.go

@@ -4,6 +4,8 @@ import (
 	"crypto/rand"
 	"net"
 	"sync"
+
+	"golang.org/x/net/ipv4"
 )
 
 // Sender sends sACN (E1.31) packets
@@ -16,13 +18,25 @@ type Sender struct {
 }
 
 // NewSender creates a new sACN sender
-func NewSender(sourceName string) (*Sender, error) {
+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
 	}
 
-	// Generate random CID
+	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[:])