// SetMulticastLoopback sets whether transmitted multicast packets
// should be copied and send back to the originator.
func (c *dgramOpt) SetMulticastLoopback(on bool) error {
	if !c.ok() {
		return syscall.EINVAL
	}
	s, err := netreflect.PacketSocketOf(c.PacketConn)
	if err != nil {
		return err
	}
	return setInt(s, &sockOpts[ssoMulticastLoopback], boolint(on))
}

// SetMulticastInterface sets the default interface for future
// multicast packet transmissions.
func (c *dgramOpt) SetMulticastInterface(ifi *net.Interface) error {
	if !c.ok() {
		return syscall.EINVAL
	}
	s, err := netreflect.PacketSocketOf(c.PacketConn)
	if err != nil {
		return err
	}
	return setInterface(s, &sockOpts[ssoMulticastInterface], ifi)
}

// ICMPFilter returns an ICMP filter.
// Currently only Linux supports this.
func (c *dgramOpt) ICMPFilter() (*ICMPFilter, error) {
	if !c.ok() {
		return nil, syscall.EINVAL
	}
	s, err := netreflect.PacketSocketOf(c.PacketConn)
	if err != nil {
		return nil, err
	}
	return getICMPFilter(s, &sockOpts[ssoICMPFilter])
}

// MulticastInterface returns the default interface for multicast
// packet transmissions.
func (c *dgramOpt) MulticastInterface() (*net.Interface, error) {
	if !c.ok() {
		return nil, syscall.EINVAL
	}
	s, err := netreflect.PacketSocketOf(c.PacketConn)
	if err != nil {
		return nil, err
	}
	return getInterface(s, &sockOpts[ssoMulticastInterface])
}

// SetICMPFilter deploys the ICMP filter.
// Currently only Linux supports this.
func (c *dgramOpt) SetICMPFilter(f *ICMPFilter) error {
	if !c.ok() {
		return syscall.EINVAL
	}
	s, err := netreflect.PacketSocketOf(c.PacketConn)
	if err != nil {
		return err
	}
	return setICMPFilter(s, &sockOpts[ssoICMPFilter], f)
}

// MulticastTTL returns the time-to-live field value for outgoing
// multicast packets.
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])
}

// SetControlMessage sets the per packet IP-level socket options.
func (c *PacketConn) SetControlMessage(cf ControlFlags, on bool) error {
	if !c.payloadHandler.ok() {
		return syscall.EINVAL
	}
	s, err := netreflect.PacketSocketOf(c.dgramOpt.PacketConn)
	if err != nil {
		return err
	}
	return setControlMessage(s, &c.payloadHandler.rawOpt, cf, on)
}

// SetMulticastHopLimit sets the hop limit field value for future
// outgoing multicast packets.
func (c *dgramOpt) SetMulticastHopLimit(hoplim int) error {
	if !c.ok() {
		return syscall.EINVAL
	}
	s, err := netreflect.PacketSocketOf(c.PacketConn)
	if err != nil {
		return err
	}
	return setInt(s, &sockOpts[ssoMulticastHopLimit], hoplim)
}

// SetMulticastTTL sets the time-to-live field value for future
// outgoing multicast packets.
func (c *dgramOpt) SetMulticastTTL(ttl int) error {
	if !c.ok() {
		return syscall.EINVAL
	}
	s, err := netreflect.PacketSocketOf(c.PacketConn)
	if err != nil {
		return err
	}
	return setInt(s, &sockOpts[ssoMulticastTTL], ttl)
}

// SetBPF attaches a BPF program to the connection.
//
// Only supported on Linux.
func (c *dgramOpt) SetBPF(filter []bpf.RawInstruction) error {
	s, err := netreflect.PacketSocketOf(c.PacketConn)
	if err != nil {
		return err
	}
	prog := sockFProg{
		Len:    uint16(len(filter)),
		Filter: (*sockFilter)(unsafe.Pointer(&filter[0])),
	}
	return os.NewSyscallError("setsockopt", setsockopt(s, sysSOL_SOCKET, sysSO_ATTACH_FILTER, unsafe.Pointer(&prog), uint32(unsafe.Sizeof(prog))))
}

// NewPacketConn returns a new PacketConn using c as its underlying
// transport.
func NewPacketConn(c net.PacketConn) *PacketConn {
	p := &PacketConn{
		genericOpt:     genericOpt{Conn: c.(net.Conn)},
		dgramOpt:       dgramOpt{PacketConn: c},
		payloadHandler: payloadHandler{PacketConn: c},
	}
	if _, ok := c.(*net.IPConn); ok && sockOpts[ssoStripHeader].name > 0 {
		if s, err := netreflect.PacketSocketOf(c); err == nil {
			setInt(s, &sockOpts[ssoStripHeader], boolint(true))
		}
	}
	return p
}

// SetChecksum enables the kernel checksum processing.  If on is ture,
// the offset should be an offset in bytes into the data of where the
// checksum field is located.
func (c *dgramOpt) SetChecksum(on bool, offset int) error {
	if !c.ok() {
		return syscall.EINVAL
	}
	s, err := netreflect.PacketSocketOf(c.PacketConn)
	if err != nil {
		return err
	}
	if !on {
		offset = -1
	}
	return setInt(s, &sockOpts[ssoChecksum], offset)
}

// MulticastLoopback reports whether transmitted multicast packets
// should be copied and send back to the originator.
func (c *dgramOpt) MulticastLoopback() (bool, error) {
	if !c.ok() {
		return false, syscall.EINVAL
	}
	s, err := netreflect.PacketSocketOf(c.PacketConn)
	if err != nil {
		return false, err
	}
	on, err := getInt(s, &sockOpts[ssoMulticastLoopback])
	if err != nil {
		return false, err
	}
	return on == 1, nil
}

// LeaveGroup leaves the group address group on the interface ifi
// regardless of whether the group is any-source group or
// source-specific group.
func (c *dgramOpt) LeaveGroup(ifi *net.Interface, group net.Addr) error {
	if !c.ok() {
		return syscall.EINVAL
	}
	s, err := netreflect.PacketSocketOf(c.PacketConn)
	if err != nil {
		return err
	}
	grp := netAddrToIP4(group)
	if grp == nil {
		return errMissingAddress
	}
	return setGroup(s, &sockOpts[ssoLeaveGroup], ifi, grp)
}

// NewRawConn returns a new RawConn using c as its underlying
// transport.
func NewRawConn(c net.PacketConn) (*RawConn, error) {
	r := &RawConn{
		genericOpt:    genericOpt{Conn: c.(net.Conn)},
		dgramOpt:      dgramOpt{PacketConn: c},
		packetHandler: packetHandler{c: c.(*net.IPConn)},
	}
	s, err := netreflect.PacketSocketOf(c)
	if err != nil {
		return nil, err
	}
	if err := setInt(s, &sockOpts[ssoHeaderPrepend], boolint(true)); err != nil {
		return nil, err
	}
	return r, nil
}

// Checksum reports whether the kernel will compute, store or verify a
// checksum for both incoming and outgoing packets.  If on is true, it
// returns an offset in bytes into the data of where the checksum
// field is located.
func (c *dgramOpt) Checksum() (on bool, offset int, err error) {
	if !c.ok() {
		return false, 0, syscall.EINVAL
	}
	s, err := netreflect.PacketSocketOf(c.PacketConn)
	if err != nil {
		return false, 0, err
	}
	offset, err = getInt(s, &sockOpts[ssoChecksum])
	if err != nil {
		return false, 0, err
	}
	if offset < 0 {
		return false, 0, nil
	}
	return true, offset, nil
}

// IncludeSourceSpecificGroup includes the excluded source-specific
// group by ExcludeSourceSpecificGroup again on the interface ifi.
func (c *dgramOpt) IncludeSourceSpecificGroup(ifi *net.Interface, group, source net.Addr) error {
	if !c.ok() {
		return syscall.EINVAL
	}
	s, err := netreflect.PacketSocketOf(c.PacketConn)
	if err != nil {
		return err
	}
	grp := netAddrToIP4(group)
	if grp == nil {
		return errMissingAddress
	}
	src := netAddrToIP4(source)
	if src == nil {
		return errMissingAddress
	}
	return setSourceGroup(s, &sockOpts[ssoUnblockSourceGroup], ifi, grp, src)
}

func TestPacketSocketOf(t *testing.T) {
	for _, network := range []string{"udp", "unixgram"} {
		switch network {
		case "unixgram":
			switch runtime.GOOS {
			case "nacl", "plan9", "windows":
				continue
			}
		}
		c, err := newLocalPacketListener(network)
		if err != nil {
			t.Error(err)
			continue
		}
		defer c.Close()
		if _, err := netreflect.PacketSocketOf(c); err != nil {
			t.Error(err)
			continue
		}
	}
}