// Copyright 2012 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 windows

package ipv4

import (
	"net"
	"syscall"
)

// 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
	}
	fd, err := c.sysfd()
	if err != nil {
		return 0, err
	}
	return getInt(fd, &sockOpts[ssoMulticastTTL])
}

// 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
	}
	fd, err := c.sysfd()
	if err != nil {
		return err
	}
	return setInt(fd, &sockOpts[ssoMulticastTTL], ttl)
}

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

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

// 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
	}
	fd, err := c.sysfd()
	if err != nil {
		return false, err
	}
	on, err := getInt(fd, &sockOpts[ssoMulticastLoopback])
	if err != nil {
		return false, err
	}
	return on == 1, nil
}

// 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
	}
	fd, err := c.sysfd()
	if err != nil {
		return err
	}
	return setInt(fd, &sockOpts[ssoMulticastLoopback], boolint(on))
}

// JoinGroup joins the group address group on the interface ifi.
// It uses the system assigned multicast interface when ifi is nil,
// although this is not recommended because the assignment depends on
// platforms and sometimes it might require routing configuration.
func (c *dgramOpt) JoinGroup(ifi *net.Interface, group net.Addr) error {
	if !c.ok() {
		return syscall.EINVAL
	}
	fd, err := c.sysfd()
	if err != nil {
		return err
	}
	grp := netAddrToIP4(group)
	if grp == nil {
		return errMissingAddress
	}
	return setGroup(fd, &sockOpts[ssoJoinGroup], ifi, grp)
}

// LeaveGroup leaves the group address group on the interface ifi.
func (c *dgramOpt) LeaveGroup(ifi *net.Interface, group net.Addr) error {
	if !c.ok() {
		return syscall.EINVAL
	}
	fd, err := c.sysfd()
	if err != nil {
		return err
	}
	grp := netAddrToIP4(group)
	if grp == nil {
		return errMissingAddress
	}
	return setGroup(fd, &sockOpts[ssoLeaveGroup], ifi, grp)
}