import "golang.org/x/net/ipv6"
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.
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)
}
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
}
}
}
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
}
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.
control.go control_rfc3542_unix.go control_unix.go dgramopt_posix.go doc.go endpoint.go genericopt_posix.go header.go helper.go helper_unix.go iana.go icmp.go icmp_linux.go payload.go payload_cmsg.go sockopt.go sockopt_asmreq_unix.go sockopt_ssmreq_unix.go sockopt_unix.go sys_linux.go syscall_unix.go zsys_linux_amd64.go
const (
Version = 6 // protocol version
HeaderLen = 40 // header length
)type Conn struct {
// contains filtered or unexported fields
}A Conn represents a network endpoint that uses IPv6 transport. It allows to set basic IP-level socket options such as traffic class and hop limit.
Code:
ln, err := net.Listen("tcp", "[::]:1024")
if err != nil {
log.Fatal(err)
}
defer ln.Close()
for {
c, err := ln.Accept()
if err != nil {
log.Fatal(err)
}
go func(c net.Conn) {
defer c.Close()
if c.RemoteAddr().(*net.TCPAddr).IP.To16() != nil && c.RemoteAddr().(*net.TCPAddr).IP.To4() == nil {
p := ipv6.NewConn(c)
if err := p.SetTrafficClass(0x28); err != nil { // DSCP AF11
log.Fatal(err)
}
if err := p.SetHopLimit(128); err != nil {
log.Fatal(err)
}
}
if _, err := c.Write([]byte("HELLO-R-U-THERE-ACK")); err != nil {
log.Fatal(err)
}
}(c)
}
NewConn returns a new Conn.
HopLimit returns the hop limit field value for outgoing packets.
PathMTU returns a path MTU value for the destination associated with the endpoint.
SetHopLimit sets the hop limit field value for future outgoing packets.
SetTrafficClass sets the traffic class field value for future outgoing packets.
TrafficClass returns the traffic class field value for outgoing packets.
A ControlFlags represents per packet basis IP-level socket option control flags.
const (
FlagTrafficClass ControlFlags = 1 << iota // pass the traffic class on the received packet
FlagHopLimit // pass the hop limit 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
FlagPathMTU // pass the path MTU on the received packet path
)type ControlMessage struct {
// Receiving socket options: SetControlMessage allows to
// receive the options from the protocol stack using ReadFrom
// method of PacketConn.
//
// Specifying socket options: ControlMessage for WriteTo
// method of PacketConn allows to send the options to the
// protocol stack.
//
TrafficClass int // traffic class, must be 1 <= value <= 255 when specifying
HopLimit int // hop limit, must be 1 <= value <= 255 when specifying
Src net.IP // source address, specifying only
Dst net.IP // destination address, receiving only
IfIndex int // interface index, must be 1 <= value when specifying
NextHop net.IP // next hop address, specifying only
MTU int // path MTU, receiving only
}A ControlMessage represents per packet basis IP-level socket options.
func (cm *ControlMessage) String() string
type Header struct {
Version int // protocol version
TrafficClass int // traffic class
FlowLabel int // flow label
PayloadLen int // payload length
NextHeader int // next header
HopLimit int // hop limit
Src net.IP // source address
Dst net.IP // destination address
}A Header represents an IPv6 base header.
ParseHeader parses b as an IPv6 base header.
type ICMPFilter struct {
// contains filtered or unexported fields
}An ICMPFilter represents an ICMP message filter for incoming packets. The filter belongs to a packet delivery path on a host and it cannot interact with forwarding packets or tunnel-outer packets.
Note: RFC 2460 defines a reasonable role model. A node means a device that implements IP. A router means a node that forwards IP packets not explicitly addressed to itself, and a host means a node that is not a router.
func (f *ICMPFilter) Accept(typ ICMPType)
Accept accepts incoming ICMP packets including the type field value typ.
func (f *ICMPFilter) Block(typ ICMPType)
Block blocks incoming ICMP packets including the type field value typ.
func (f *ICMPFilter) SetAll(block bool)
SetAll sets the filter action to the filter.
func (f *ICMPFilter) WillBlock(typ ICMPType) bool
WillBlock reports whether the ICMP type will be blocked.
An ICMPType represents a type of ICMP message.
const (
ICMPTypeDestinationUnreachable ICMPType = 1 // Destination Unreachable
ICMPTypePacketTooBig ICMPType = 2 // Packet Too Big
ICMPTypeTimeExceeded ICMPType = 3 // Time Exceeded
ICMPTypeParameterProblem ICMPType = 4 // Parameter Problem
ICMPTypeEchoRequest ICMPType = 128 // Echo Request
ICMPTypeEchoReply ICMPType = 129 // Echo Reply
ICMPTypeMulticastListenerQuery ICMPType = 130 // Multicast Listener Query
ICMPTypeMulticastListenerReport ICMPType = 131 // Multicast Listener Report
ICMPTypeMulticastListenerDone ICMPType = 132 // Multicast Listener Done
ICMPTypeRouterSolicitation ICMPType = 133 // Router Solicitation
ICMPTypeRouterAdvertisement ICMPType = 134 // Router Advertisement
ICMPTypeNeighborSolicitation ICMPType = 135 // Neighbor Solicitation
ICMPTypeNeighborAdvertisement ICMPType = 136 // Neighbor Advertisement
ICMPTypeRedirect ICMPType = 137 // Redirect Message
ICMPTypeRouterRenumbering ICMPType = 138 // Router Renumbering
ICMPTypeNodeInformationQuery ICMPType = 139 // ICMP Node Information Query
ICMPTypeNodeInformationResponse ICMPType = 140 // ICMP Node Information Response
ICMPTypeInverseNeighborDiscoverySolicitation ICMPType = 141 // Inverse Neighbor Discovery Solicitation Message
ICMPTypeInverseNeighborDiscoveryAdvertisement ICMPType = 142 // Inverse Neighbor Discovery Advertisement Message
ICMPTypeVersion2MulticastListenerReport ICMPType = 143 // Version 2 Multicast Listener Report
ICMPTypeHomeAgentAddressDiscoveryRequest ICMPType = 144 // Home Agent Address Discovery Request Message
ICMPTypeHomeAgentAddressDiscoveryReply ICMPType = 145 // Home Agent Address Discovery Reply Message
ICMPTypeMobilePrefixSolicitation ICMPType = 146 // Mobile Prefix Solicitation
ICMPTypeMobilePrefixAdvertisement ICMPType = 147 // Mobile Prefix Advertisement
ICMPTypeCertificationPathSolicitation ICMPType = 148 // Certification Path Solicitation Message
ICMPTypeCertificationPathAdvertisement ICMPType = 149 // Certification Path Advertisement Message
ICMPTypeMulticastRouterAdvertisement ICMPType = 151 // Multicast Router Advertisement
ICMPTypeMulticastRouterSolicitation ICMPType = 152 // Multicast Router Solicitation
ICMPTypeMulticastRouterTermination ICMPType = 153 // Multicast Router Termination
ICMPTypeFMIPv6 ICMPType = 154 // FMIPv6 Messages
ICMPTypeRPLControl ICMPType = 155 // RPL Control Message
ICMPTypeILNPv6LocatorUpdate ICMPType = 156 // ILNPv6 Locator Update Message
ICMPTypeDuplicateAddressRequest ICMPType = 157 // Duplicate Address Request
ICMPTypeDuplicateAddressConfirmation ICMPType = 158 // Duplicate Address Confirmation
ICMPTypeMPLControl ICMPType = 159 // MPL Control Message
)Internet Control Message Protocol version 6 (ICMPv6) Parameters, Updated: 2015-07-07
Protocol returns the ICMPv6 protocol number.
type PacketConn struct {
// contains filtered or unexported fields
}A PacketConn represents a packet network endpoint that uses IPv6 transport. It is used to control several IP-level socket options including IPv6 header manipulation. It also provides datagram based network I/O methods specific to the IPv6 and higher layer protocols such as OSPF, GRE, and UDP.
Code:
c, err := net.ListenPacket("ip6:89", "::") // OSPF for IPv6
if err != nil {
log.Fatal(err)
}
defer c.Close()
p := ipv6.NewPacketConn(c)
en0, err := net.InterfaceByName("en0")
if err != nil {
log.Fatal(err)
}
allSPFRouters := net.IPAddr{IP: net.ParseIP("ff02::5")}
if err := p.JoinGroup(en0, &allSPFRouters); err != nil {
log.Fatal(err)
}
defer p.LeaveGroup(en0, &allSPFRouters)
hello := make([]byte, 24) // fake hello data, you need to implement this
ospf := make([]byte, 16) // fake ospf header, you need to implement this
ospf[0] = 3 // version 3
ospf[1] = 1 // hello packet
ospf = append(ospf, hello...)
if err := p.SetChecksum(true, 12); err != nil {
log.Fatal(err)
}
cm := ipv6.ControlMessage{
TrafficClass: 0xc0, // DSCP CS6
HopLimit: 1,
IfIndex: en0.Index,
}
if _, err := p.WriteTo(ospf, &cm, &allSPFRouters); err != nil {
log.Fatal(err)
}
Code:
c, err := net.ListenPacket("udp6", "[::]:5353") // mDNS over UDP
if err != nil {
log.Fatal(err)
}
defer c.Close()
p := ipv6.NewPacketConn(c)
en0, err := net.InterfaceByName("en0")
if err != nil {
log.Fatal(err)
}
mDNSLinkLocal := net.UDPAddr{IP: net.ParseIP("ff02::fb")}
if err := p.JoinGroup(en0, &mDNSLinkLocal); err != nil {
log.Fatal(err)
}
defer p.LeaveGroup(en0, &mDNSLinkLocal)
if err := p.SetControlMessage(ipv6.FlagDst|ipv6.FlagInterface, true); err != nil {
log.Fatal(err)
}
var wcm ipv6.ControlMessage
b := make([]byte, 1500)
for {
_, rcm, peer, err := p.ReadFrom(b)
if err != nil {
log.Fatal(err)
}
if !rcm.Dst.IsMulticast() || !rcm.Dst.Equal(mDNSLinkLocal.IP) {
continue
}
wcm.IfIndex = rcm.IfIndex
answers := []byte("FAKE-MDNS-ANSWERS") // fake mDNS answers, you need to implement this
if _, err := p.WriteTo(answers, &wcm, peer); err != nil {
log.Fatal(err)
}
}
Code:
// Tracing an IP packet route to www.google.com. const host = "www.google.com" ips, err := net.LookupIP(host) if err != nil { log.Fatal(err) } var dst net.IPAddr for _, ip := range ips { if ip.To16() != nil && ip.To4() == nil { dst.IP = ip fmt.Printf("using %v for tracing an IP packet route to %s\n", dst.IP, host) break } } if dst.IP == nil { log.Fatal("no AAAA record found") } c, err := net.ListenPacket("ip6:58", "::") // ICMP for IPv6 if err != nil { log.Fatal(err) } defer c.Close() p := ipv6.NewPacketConn(c) if err := p.SetControlMessage(ipv6.FlagHopLimit|ipv6.FlagSrc|ipv6.FlagDst|ipv6.FlagInterface, true); err != nil { log.Fatal(err) } wm := icmp.Message{ Type: ipv6.ICMPTypeEchoRequest, Code: 0, Body: &icmp.Echo{ ID: os.Getpid() & 0xffff, Data: []byte("HELLO-R-U-THERE"), }, } var f ipv6.ICMPFilter f.SetAll(true) f.Accept(ipv6.ICMPTypeTimeExceeded) f.Accept(ipv6.ICMPTypeEchoReply) if err := p.SetICMPFilter(&f); err != nil { log.Fatal(err) } var wcm ipv6.ControlMessage rb := make([]byte, 1500) for i := 1; i <= 64; i++ { // up to 64 hops wm.Body.(*icmp.Echo).Seq = i wb, err := wm.Marshal(nil) if err != nil { log.Fatal(err) } // In the real world usually there are several // multiple traffic-engineered paths for each hop. // You may need to probe a few times to each hop. begin := time.Now() wcm.HopLimit = i if _, err := p.WriteTo(wb, &wcm, &dst); err != nil { log.Fatal(err) } if err := p.SetReadDeadline(time.Now().Add(3 * time.Second)); err != nil { log.Fatal(err) } n, rcm, peer, err := p.ReadFrom(rb) if err != nil { if err, ok := err.(net.Error); ok && err.Timeout() { fmt.Printf("%v\t*\n", i) continue } log.Fatal(err) } rm, err := icmp.ParseMessage(58, rb[:n]) if err != nil { log.Fatal(err) } rtt := time.Since(begin) // In the real world you need to determine whether the // received message is yours using ControlMessage.Src, // ControlMesage.Dst, icmp.Echo.ID and icmp.Echo.Seq. switch rm.Type { case ipv6.ICMPTypeTimeExceeded: names, _ := net.LookupAddr(peer.String()) fmt.Printf("%d\t%v %+v %v\n\t%+v\n", i, peer, names, rtt, rcm) case ipv6.ICMPTypeEchoReply: names, _ := net.LookupAddr(peer.String()) fmt.Printf("%d\t%v %+v %v\n\t%+v\n", i, peer, names, rtt, rcm) return } }
func NewPacketConn(c net.PacketConn) *PacketConn
NewPacketConn returns a new PacketConn using c as its underlying transport.
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 *PacketConn) Close() error
Close closes the endpoint.
ExcludeSourceSpecificGroup excludes the source-specific group from the already joined any-source groups by JoinGroup on the interface ifi.
HopLimit returns the hop limit field value for outgoing packets.
func (c *PacketConn) ICMPFilter() (*ICMPFilter, error)
ICMPFilter returns an ICMP filter.
IncludeSourceSpecificGroup includes the excluded source-specific group by ExcludeSourceSpecificGroup again on the interface ifi.
JoinGroup joins the group address group on the interface ifi. By default all sources that can cast data to group are accepted. It's possible to mute and unmute data transmission from a specific source by using ExcludeSourceSpecificGroup and IncludeSourceSpecificGroup. JoinGroup 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.
JoinSourceSpecificGroup joins the source-specific group comprising group and source on the interface ifi. JoinSourceSpecificGroup 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.
LeaveGroup leaves the group address group on the interface ifi regardless of whether the group is any-source group or source-specific group.
LeaveSourceSpecificGroup leaves the source-specific group on the interface ifi.
MulticastHopLimit returns the hop limit field value for outgoing multicast packets.
MulticastInterface returns the default interface for multicast packet transmissions.
MulticastLoopback reports whether transmitted multicast packets should be copied and send back to the originator.
ReadFrom reads a payload of the received IPv6 datagram, from the endpoint c, copying the payload into b. It returns the number of bytes copied into b, the control message cm and the source address src of the received datagram.
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 *PacketConn) SetControlMessage(cf ControlFlags, on bool) error
SetControlMessage allows to receive the per packet basis IP-level socket options.
func (c *PacketConn) SetDeadline(t time.Time) error
SetDeadline sets the read and write deadlines associated with the endpoint.
SetHopLimit sets the hop limit field value for future outgoing packets.
func (c *PacketConn) SetICMPFilter(f *ICMPFilter) error
SetICMPFilter deploys the ICMP filter.
SetMulticastHopLimit sets the hop limit field value for future outgoing multicast packets.
SetMulticastInterface sets the default interface for future multicast packet transmissions.
SetMulticastLoopback sets whether transmitted multicast packets should be copied and send back to the originator.
func (c *PacketConn) SetReadDeadline(t time.Time) error
SetReadDeadline sets the read deadline associated with the endpoint.
SetTrafficClass sets the traffic class field value for future outgoing packets.
func (c *PacketConn) SetWriteDeadline(t time.Time) error
SetWriteDeadline sets the write deadline associated with the endpoint.
TrafficClass returns the traffic class field value for outgoing packets.
WriteTo writes a payload of the IPv6 datagram, to the destination address dst through the endpoint c, copying the payload from b. It returns the number of bytes written. The control message cm allows the IPv6 header fields and the datagram path to be specified. The cm may be nil if control of the outgoing datagram is not required.
Package ipv6 imports 11 packages (graph) and is imported by 23 packages. Updated 6 days ago. Refresh now. Tools for package owners.