| // 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. |
| |
| // Package ipv6 implements IP-level socket options for the Internet |
| // Protocol version 6. |
| // |
| // The package provides IP-level socket options that allow |
| // manipulation of IPv6 facilities. |
| // |
| // The IPv6 protocol is defined in RFC 2460. |
| // Basic and advanced socket interface extensions are defined in RFC |
| // 3493 and RFC 3542. |
| // Socket interface extensions for multicast source filters are |
| // defined in RFC 3678. |
| // MLDv1 and MLDv2 are defined in RFC 2710 and RFC 3810. |
| // Source-specific multicast is defined in RFC 4607. |
| // |
| // |
| // Unicasting |
| // |
| // The options for unicasting are available for net.TCPConn, |
| // net.UDPConn and net.IPConn which are created as network connections |
| // that use the IPv6 transport. When a single TCP connection carrying |
| // a data flow of multiple packets needs to indicate the flow is |
| // important, ipv6.Conn is used to set the traffic class field on the |
| // IPv6 header for each packet. |
| // |
| // ln, err := net.Listen("tcp6", "[::]:1024") |
| // if err != nil { |
| // // error handling |
| // } |
| // defer ln.Close() |
| // for { |
| // c, err := ln.Accept() |
| // if err != nil { |
| // // error handling |
| // } |
| // go func(c net.Conn) { |
| // defer c.Close() |
| // |
| // The outgoing packets will be labeled DiffServ assured forwarding |
| // class 1 low drop precedence, known as AF11 packets. |
| // |
| // if err := ipv6.NewConn(c).SetTrafficClass(0x28); err != nil { |
| // // error handling |
| // } |
| // if _, err := c.Write(data); err != nil { |
| // // error handling |
| // } |
| // }(c) |
| // } |
| // |
| // |
| // Multicasting |
| // |
| // The options for multicasting are available for net.UDPConn and |
| // net.IPconn which are created as network connections that use the |
| // IPv6 transport. A few network facilities must be prepared before |
| // you begin multicasting, at a minimum joining network interfaces and |
| // multicast groups. |
| // |
| // en0, err := net.InterfaceByName("en0") |
| // if err != nil { |
| // // error handling |
| // } |
| // en1, err := net.InterfaceByIndex(911) |
| // if err != nil { |
| // // error handling |
| // } |
| // group := net.ParseIP("ff02::114") |
| // |
| // First, an application listens to an appropriate address with an |
| // appropriate service port. |
| // |
| // c, err := net.ListenPacket("udp6", "[::]:1024") |
| // if err != nil { |
| // // error handling |
| // } |
| // defer c.Close() |
| // |
| // Second, the application joins multicast groups, starts listening to |
| // the groups on the specified network interfaces. Note that the |
| // service port for transport layer protocol does not matter with this |
| // operation as joining groups affects only network and link layer |
| // protocols, such as IPv6 and Ethernet. |
| // |
| // p := ipv6.NewPacketConn(c) |
| // if err := p.JoinGroup(en0, &net.UDPAddr{IP: group}); err != nil { |
| // // error handling |
| // } |
| // if err := p.JoinGroup(en1, &net.UDPAddr{IP: group}); err != nil { |
| // // error handling |
| // } |
| // |
| // The application might set per packet control message transmissions |
| // between the protocol stack within the kernel. When the application |
| // needs a destination address on an incoming packet, |
| // SetControlMessage of ipv6.PacketConn is used to enable control |
| // message transmissons. |
| // |
| // if err := p.SetControlMessage(ipv6.FlagDst, true); err != nil { |
| // // error handling |
| // } |
| // |
| // The application could identify whether the received packets are |
| // of interest by using the control message that contains the |
| // destination address of the received packet. |
| // |
| // b := make([]byte, 1500) |
| // for { |
| // n, rcm, src, err := p.ReadFrom(b) |
| // if err != nil { |
| // // error handling |
| // } |
| // if rcm.Dst.IsMulticast() { |
| // if rcm.Dst.Equal(group) { |
| // // joined group, do something |
| // } else { |
| // // unknown group, discard |
| // continue |
| // } |
| // } |
| // |
| // The application can also send both unicast and multicast packets. |
| // |
| // p.SetTrafficClass(0x0) |
| // p.SetHopLimit(16) |
| // if _, err := p.WriteTo(data[:n], nil, src); err != nil { |
| // // error handling |
| // } |
| // dst := &net.UDPAddr{IP: group, Port: 1024} |
| // wcm := ipv6.ControlMessage{TrafficClass: 0xe0, HopLimit: 1} |
| // for _, ifi := range []*net.Interface{en0, en1} { |
| // wcm.IfIndex = ifi.Index |
| // if _, err := p.WriteTo(data[:n], &wcm, dst); err != nil { |
| // // error handling |
| // } |
| // } |
| // } |
| // |
| // |
| // More multicasting |
| // |
| // An application that uses PacketConn may join multiple multicast |
| // groups. For example, a UDP listener with port 1024 might join two |
| // different groups across over two different network interfaces by |
| // using: |
| // |
| // c, err := net.ListenPacket("udp6", "[::]:1024") |
| // if err != nil { |
| // // error handling |
| // } |
| // defer c.Close() |
| // p := ipv6.NewPacketConn(c) |
| // if err := p.JoinGroup(en0, &net.UDPAddr{IP: net.ParseIP("ff02::1:114")}); err != nil { |
| // // error handling |
| // } |
| // if err := p.JoinGroup(en0, &net.UDPAddr{IP: net.ParseIP("ff02::2:114")}); err != nil { |
| // // error handling |
| // } |
| // if err := p.JoinGroup(en1, &net.UDPAddr{IP: net.ParseIP("ff02::2:114")}); err != nil { |
| // // error handling |
| // } |
| // |
| // It is possible for multiple UDP listeners that listen on the same |
| // UDP port to join the same multicast group. The net package will |
| // provide a socket that listens to a wildcard address with reusable |
| // UDP port when an appropriate multicast address prefix is passed to |
| // the net.ListenPacket or net.ListenUDP. |
| // |
| // c1, err := net.ListenPacket("udp6", "[ff02::]:1024") |
| // if err != nil { |
| // // error handling |
| // } |
| // defer c1.Close() |
| // c2, err := net.ListenPacket("udp6", "[ff02::]:1024") |
| // if err != nil { |
| // // error handling |
| // } |
| // defer c2.Close() |
| // p1 := ipv6.NewPacketConn(c1) |
| // if err := p1.JoinGroup(en0, &net.UDPAddr{IP: net.ParseIP("ff02::114")}); err != nil { |
| // // error handling |
| // } |
| // p2 := ipv6.NewPacketConn(c2) |
| // if err := p2.JoinGroup(en0, &net.UDPAddr{IP: net.ParseIP("ff02::114")}); err != nil { |
| // // error handling |
| // } |
| // |
| // Also it is possible for the application to leave or rejoin a |
| // multicast group on the network interface. |
| // |
| // if err := p.LeaveGroup(en0, &net.UDPAddr{IP: net.ParseIP("ff02::114")}); err != nil { |
| // // error handling |
| // } |
| // if err := p.JoinGroup(en0, &net.UDPAddr{IP: net.ParseIP("ff01::114")}); err != nil { |
| // // error handling |
| // } |
| // |
| // |
| // Source-specific multicasting |
| // |
| // An application that uses PacketConn on MLDv2 supported platform is |
| // able to join source-specific multicast groups. |
| // The application may use JoinSourceSpecificGroup and |
| // LeaveSourceSpecificGroup for the operation known as "include" mode, |
| // |
| // ssmgroup := net.UDPAddr{IP: net.ParseIP("ff32::8000:9")} |
| // ssmsource := net.UDPAddr{IP: net.ParseIP("fe80::cafe")} |
| // if err := p.JoinSourceSpecificGroup(en0, &ssmgroup, &ssmsource); err != nil { |
| // // error handling |
| // } |
| // if err := p.LeaveSourceSpecificGroup(en0, &ssmgroup, &ssmsource); err != nil { |
| // // error handling |
| // } |
| // |
| // or JoinGroup, ExcludeSourceSpecificGroup, |
| // IncludeSourceSpecificGroup and LeaveGroup for the operation known |
| // as "exclude" mode. |
| // |
| // exclsource := net.UDPAddr{IP: net.ParseIP("fe80::dead")} |
| // if err := p.JoinGroup(en0, &ssmgroup); err != nil { |
| // // error handling |
| // } |
| // if err := p.ExcludeSourceSpecificGroup(en0, &ssmgroup, &exclsource); err != nil { |
| // // error handling |
| // } |
| // if err := p.LeaveGroup(en0, &ssmgroup); err != nil { |
| // // error handling |
| // } |
| // |
| // Note that it depends on each platform implementation what happens |
| // when an application which runs on MLDv2 unsupported platform uses |
| // JoinSourceSpecificGroup and LeaveSourceSpecificGroup. |
| // In general the platform tries to fall back to conversations using |
| // MLDv1 and starts to listen to multicast traffic. |
| // In the fallback case, ExcludeSourceSpecificGroup and |
| // IncludeSourceSpecificGroup may return an error. |
| package ipv6 // import "golang.org/x/net/ipv6" |
