240 lines
7.7 KiB
Go
240 lines
7.7 KiB
Go
// Copyright 2013 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package ipv6 implements IP-level socket options for the Internet
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// Protocol version 6.
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//
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// The package provides IP-level socket options that allow
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// manipulation of IPv6 facilities.
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//
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// The IPv6 protocol is defined in RFC 8200.
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// Socket interface extensions are defined in RFC 3493, RFC 3542 and
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// RFC 3678.
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// MLDv1 and MLDv2 are defined in RFC 2710 and RFC 3810.
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// Source-specific multicast is defined in RFC 4607.
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//
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// On Darwin, this package requires OS X Mavericks version 10.9 or
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// above, or equivalent.
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//
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// # Unicasting
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//
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// The options for unicasting are available for net.TCPConn,
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// net.UDPConn and net.IPConn which are created as network connections
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// that use the IPv6 transport. When a single TCP connection carrying
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// a data flow of multiple packets needs to indicate the flow is
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// important, Conn is used to set the traffic class field on the IPv6
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// header for each packet.
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//
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// ln, err := net.Listen("tcp6", "[::]:1024")
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// if err != nil {
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// // error handling
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// }
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// defer ln.Close()
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// for {
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// c, err := ln.Accept()
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// if err != nil {
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// // error handling
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// }
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// go func(c net.Conn) {
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// defer c.Close()
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//
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// The outgoing packets will be labeled DiffServ assured forwarding
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// class 1 low drop precedence, known as AF11 packets.
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//
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// if err := ipv6.NewConn(c).SetTrafficClass(0x28); err != nil {
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// // error handling
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// }
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// if _, err := c.Write(data); err != nil {
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// // error handling
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// }
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// }(c)
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// }
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//
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// # Multicasting
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//
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// The options for multicasting are available for net.UDPConn and
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// net.IPConn which are created as network connections that use the
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// IPv6 transport. A few network facilities must be prepared before
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// you begin multicasting, at a minimum joining network interfaces and
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// multicast groups.
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//
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// en0, err := net.InterfaceByName("en0")
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// if err != nil {
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// // error handling
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// }
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// en1, err := net.InterfaceByIndex(911)
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// if err != nil {
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// // error handling
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// }
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// group := net.ParseIP("ff02::114")
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//
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// First, an application listens to an appropriate address with an
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// appropriate service port.
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//
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// c, err := net.ListenPacket("udp6", "[::]:1024")
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// if err != nil {
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// // error handling
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// }
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// defer c.Close()
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//
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// Second, the application joins multicast groups, starts listening to
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// the groups on the specified network interfaces. Note that the
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// service port for transport layer protocol does not matter with this
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// operation as joining groups affects only network and link layer
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// protocols, such as IPv6 and Ethernet.
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//
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// p := ipv6.NewPacketConn(c)
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// if err := p.JoinGroup(en0, &net.UDPAddr{IP: group}); err != nil {
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// // error handling
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// }
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// if err := p.JoinGroup(en1, &net.UDPAddr{IP: group}); err != nil {
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// // error handling
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// }
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//
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// The application might set per packet control message transmissions
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// between the protocol stack within the kernel. When the application
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// needs a destination address on an incoming packet,
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// SetControlMessage of PacketConn is used to enable control message
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// transmissions.
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//
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// if err := p.SetControlMessage(ipv6.FlagDst, true); err != nil {
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// // error handling
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// }
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//
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// The application could identify whether the received packets are
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// of interest by using the control message that contains the
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// destination address of the received packet.
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//
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// b := make([]byte, 1500)
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// for {
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// n, rcm, src, err := p.ReadFrom(b)
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// if err != nil {
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// // error handling
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// }
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// if rcm.Dst.IsMulticast() {
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// if rcm.Dst.Equal(group) {
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// // joined group, do something
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// } else {
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// // unknown group, discard
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// continue
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// }
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// }
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//
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// The application can also send both unicast and multicast packets.
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//
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// p.SetTrafficClass(0x0)
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// p.SetHopLimit(16)
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// if _, err := p.WriteTo(data[:n], nil, src); err != nil {
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// // error handling
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// }
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// dst := &net.UDPAddr{IP: group, Port: 1024}
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// wcm := ipv6.ControlMessage{TrafficClass: 0xe0, HopLimit: 1}
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// for _, ifi := range []*net.Interface{en0, en1} {
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// wcm.IfIndex = ifi.Index
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// if _, err := p.WriteTo(data[:n], &wcm, dst); err != nil {
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// // error handling
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// }
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// }
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// }
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//
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// # More multicasting
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//
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// An application that uses PacketConn may join multiple multicast
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// groups. For example, a UDP listener with port 1024 might join two
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// different groups across over two different network interfaces by
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// using:
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//
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// c, err := net.ListenPacket("udp6", "[::]:1024")
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// if err != nil {
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// // error handling
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// }
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// defer c.Close()
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// p := ipv6.NewPacketConn(c)
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// if err := p.JoinGroup(en0, &net.UDPAddr{IP: net.ParseIP("ff02::1:114")}); err != nil {
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// // error handling
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// }
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// if err := p.JoinGroup(en0, &net.UDPAddr{IP: net.ParseIP("ff02::2:114")}); err != nil {
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// // error handling
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// }
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// if err := p.JoinGroup(en1, &net.UDPAddr{IP: net.ParseIP("ff02::2:114")}); err != nil {
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// // error handling
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// }
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//
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// It is possible for multiple UDP listeners that listen on the same
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// UDP port to join the same multicast group. The net package will
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// provide a socket that listens to a wildcard address with reusable
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// UDP port when an appropriate multicast address prefix is passed to
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// the net.ListenPacket or net.ListenUDP.
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//
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// c1, err := net.ListenPacket("udp6", "[ff02::]:1024")
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// if err != nil {
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// // error handling
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// }
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// defer c1.Close()
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// c2, err := net.ListenPacket("udp6", "[ff02::]:1024")
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// if err != nil {
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// // error handling
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// }
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// defer c2.Close()
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// p1 := ipv6.NewPacketConn(c1)
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// if err := p1.JoinGroup(en0, &net.UDPAddr{IP: net.ParseIP("ff02::114")}); err != nil {
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// // error handling
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// }
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// p2 := ipv6.NewPacketConn(c2)
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// if err := p2.JoinGroup(en0, &net.UDPAddr{IP: net.ParseIP("ff02::114")}); err != nil {
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// // error handling
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// }
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//
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// Also it is possible for the application to leave or rejoin a
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// multicast group on the network interface.
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//
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// if err := p.LeaveGroup(en0, &net.UDPAddr{IP: net.ParseIP("ff02::114")}); err != nil {
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// // error handling
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// }
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// if err := p.JoinGroup(en0, &net.UDPAddr{IP: net.ParseIP("ff01::114")}); err != nil {
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// // error handling
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// }
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//
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// # Source-specific multicasting
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//
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// An application that uses PacketConn on MLDv2 supported platform is
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// able to join source-specific multicast groups.
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// The application may use JoinSourceSpecificGroup and
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// LeaveSourceSpecificGroup for the operation known as "include" mode,
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//
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// ssmgroup := net.UDPAddr{IP: net.ParseIP("ff32::8000:9")}
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// ssmsource := net.UDPAddr{IP: net.ParseIP("fe80::cafe")}
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// if err := p.JoinSourceSpecificGroup(en0, &ssmgroup, &ssmsource); err != nil {
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// // error handling
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// }
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// if err := p.LeaveSourceSpecificGroup(en0, &ssmgroup, &ssmsource); err != nil {
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// // error handling
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// }
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//
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// or JoinGroup, ExcludeSourceSpecificGroup,
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// IncludeSourceSpecificGroup and LeaveGroup for the operation known
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// as "exclude" mode.
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//
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// exclsource := net.UDPAddr{IP: net.ParseIP("fe80::dead")}
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// if err := p.JoinGroup(en0, &ssmgroup); err != nil {
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// // error handling
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// }
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// if err := p.ExcludeSourceSpecificGroup(en0, &ssmgroup, &exclsource); err != nil {
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// // error handling
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// }
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// if err := p.LeaveGroup(en0, &ssmgroup); err != nil {
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// // error handling
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// }
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//
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// Note that it depends on each platform implementation what happens
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// when an application which runs on MLDv2 unsupported platform uses
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// JoinSourceSpecificGroup and LeaveSourceSpecificGroup.
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// In general the platform tries to fall back to conversations using
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// MLDv1 and starts to listen to multicast traffic.
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// In the fallback case, ExcludeSourceSpecificGroup and
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// IncludeSourceSpecificGroup may return an error.
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package ipv6 // import "golang.org/x/net/ipv6"
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// BUG(mikio): This package is not implemented on JS, NaCl and Plan 9.
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