text: // Copyright 2013 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.
  
  // +build darwin dragonfly freebsd linux netbsd openbsd solaris windows
  
  package ipv6
  
  import (
  	"net"
  	"unsafe"
  
  	"golang.org/x/net/bpf"
  	"golang.org/x/net/internal/socket"
  )
  
  func (so *sockOpt) getMulticastInterface(c *socket.Conn) (*net.Interface, error) {
  	n, err := so.GetInt(c)
  	if err != nil {
  		return nil, err
  	}
  	return net.InterfaceByIndex(n)
  }
  
  func (so *sockOpt) setMulticastInterface(c *socket.Conn, ifi *net.Interface) error {
  	var n int
  	if ifi != nil {
  		n = ifi.Index
  	}
  	return so.SetInt(c, n)
  }
  
  func (so *sockOpt) getICMPFilter(c *socket.Conn) (*ICMPFilter, error) {
  	b := make([]byte, so.Len)
  	n, err := so.Get(c, b)
  	if err != nil {
  		return nil, err
  	}
  	if n != sizeofICMPv6Filter {
  		return nil, errOpNoSupport
  	}
  	return (*ICMPFilter)(unsafe.Pointer(&b[0])), nil
  }
  
  func (so *sockOpt) setICMPFilter(c *socket.Conn, f *ICMPFilter) error {
  	b := (*[sizeofICMPv6Filter]byte)(unsafe.Pointer(f))[:sizeofICMPv6Filter]
  	return so.Set(c, b)
  }
  
  func (so *sockOpt) getMTUInfo(c *socket.Conn) (*net.Interface, int, error) {
  	b := make([]byte, so.Len)
  	n, err := so.Get(c, b)
  	if err != nil {
  		return nil, 0, err
  	}
  	if n != sizeofIPv6Mtuinfo {
  		return nil, 0, errOpNoSupport
  	}
  	mi := (*ipv6Mtuinfo)(unsafe.Pointer(&b[0]))
  	if mi.Addr.Scope_id == 0 {
  		return nil, int(mi.Mtu), nil
  	}
  	ifi, err := net.InterfaceByIndex(int(mi.Addr.Scope_id))
  	if err != nil {
  		return nil, 0, err
  	}
  	return ifi, int(mi.Mtu), nil
  }
  
  func (so *sockOpt) setGroup(c *socket.Conn, ifi *net.Interface, grp net.IP) error {
  	switch so.typ {
  	case ssoTypeIPMreq:
  		return so.setIPMreq(c, ifi, grp)
  	case ssoTypeGroupReq:
  		return so.setGroupReq(c, ifi, grp)
  	default:
  		return errOpNoSupport
  	}
  }
  
  func (so *sockOpt) setSourceGroup(c *socket.Conn, ifi *net.Interface, grp, src net.IP) error {
  	return so.setGroupSourceReq(c, ifi, grp, src)
  }
  
  func (so *sockOpt) setBPF(c *socket.Conn, f []bpf.RawInstruction) error {
  	return so.setAttachFilter(c, f)
  }
  