| // Copyright 2011 The Go Authors. All rights reserved. | 
 | // Use of this source code is governed by a BSD-style | 
 | // license that can be found in the LICENSE file. | 
 |  | 
 | package net | 
 |  | 
 | import ( | 
 | 	"os" | 
 | 	"runtime" | 
 | 	"syscall" | 
 | 	"unsafe" | 
 | ) | 
 |  | 
 | func setIPv4MulticastInterface(fd *netFD, ifi *Interface) error { | 
 | 	ip, err := interfaceToIPv4Addr(ifi) | 
 | 	if err != nil { | 
 | 		return os.NewSyscallError("setsockopt", err) | 
 | 	} | 
 | 	var a [4]byte | 
 | 	copy(a[:], ip.To4()) | 
 | 	err = fd.pfd.Setsockopt(syscall.IPPROTO_IP, syscall.IP_MULTICAST_IF, (*byte)(unsafe.Pointer(&a[0])), 4) | 
 | 	runtime.KeepAlive(fd) | 
 | 	return wrapSyscallError("setsockopt", err) | 
 | } | 
 |  | 
 | func setIPv4MulticastLoopback(fd *netFD, v bool) error { | 
 | 	err := fd.pfd.SetsockoptInt(syscall.IPPROTO_IP, syscall.IP_MULTICAST_LOOP, boolint(v)) | 
 | 	runtime.KeepAlive(fd) | 
 | 	return wrapSyscallError("setsockopt", err) | 
 | } |