blob: da4da2dd0e626e0f3b169754ad051e7a95cb2ccc [file] [log] [blame]
// 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.
package ipv4
import (
type rawOpt struct {
cflags ControlFlags
func (c *rawOpt) set(f ControlFlags) { c.cflags |= f }
func (c *rawOpt) clear(f ControlFlags) { c.cflags &^= f }
func (c *rawOpt) isset(f ControlFlags) bool { return c.cflags&f != 0 }
type ControlFlags uint
const (
FlagTTL ControlFlags = 1 << iota // pass the TTL on the received packet
FlagSrc // pass the source address on the received packet
FlagDst // pass the destination address on the received packet
FlagInterface // pass the interface index on the received packet
// A ControlMessage represents per packet basis IP-level socket options.
type ControlMessage struct {
// Receiving socket options: SetControlMessage allows to
// receive the options from the protocol stack using ReadFrom
// method of PacketConn or RawConn.
// Specifying socket options: ControlMessage for WriteTo
// method of PacketConn or RawConn allows to send the options
// to the protocol stack.
TTL int // time-to-live, receiving only
Src net.IP // source address, specifying only
Dst net.IP // destination address, receiving only
IfIndex int // interface index, must be 1 <= value when specifying
func (cm *ControlMessage) String() string {
if cm == nil {
return "<nil>"
return fmt.Sprintf("ttl=%d src=%v dst=%v ifindex=%d", cm.TTL, cm.Src, cm.Dst, cm.IfIndex)
// Ancillary data socket options
const (
ctlTTL = iota // header field
ctlSrc // header field
ctlDst // header field
ctlInterface // inbound or outbound interface
ctlPacketInfo // inbound or outbound packet path
// A ctlOpt represents a binding for ancillary data socket option.
type ctlOpt struct {
name int // option name, must be equal or greater than 1
length int // option length
marshal func([]byte, *ControlMessage) []byte
parse func(*ControlMessage, []byte)