func (c *dgramOpt) MulticastTTL() (int, error) {
	if !c.ok() {
		return 0, syscall.EINVAL
	}
	s, err := netreflect.PacketSocketOf(c.PacketConn)
	if err != nil {
		return 0, err
	}
	return getInt(s, &sockOpts[ssoMulticastTTL])
}
MulticastTTL returns the time-to-live field value for outgoing
multicast packets.
package ipv4
import (
	"net"
	"syscall"
	"golang.org/x/net/internal/netreflect"
)