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Overview ¶
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 and socket options for IPv6 are defined in RFC 2460, RFC 3493 and RFC 3542.
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, as known as AF11 packets.
if err := ipv6.NewConn(c).SetTrafficClass(DiffServAF11); 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(DiffServCS0)
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: DiffServCS7, 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
}
Index ¶
- type Conn
- type ControlFlags
- type ControlMessage
- type ICMPFilter
- type ICMPType
- type PacketConn
- func (c *PacketConn) Checksum() (on bool, offset int, err error)
- func (c *PacketConn) Close() error
- func (c *PacketConn) HopLimit() (int, error)
- func (c *PacketConn) ICMPFilter() (*ICMPFilter, error)
- func (c *PacketConn) JoinGroup(ifi *net.Interface, group net.Addr) error
- func (c *PacketConn) LeaveGroup(ifi *net.Interface, group net.Addr) error
- func (c *PacketConn) MulticastHopLimit() (int, error)
- func (c *PacketConn) MulticastInterface() (*net.Interface, error)
- func (c *PacketConn) MulticastLoopback() (bool, error)
- func (c *PacketConn) ReadFrom(b []byte) (n int, cm *ControlMessage, src net.Addr, err error)
- func (c *PacketConn) SetChecksum(on bool, offset int) error
- func (c *PacketConn) SetControlMessage(cf ControlFlags, on bool) error
- func (c *PacketConn) SetDeadline(t time.Time) error
- func (c *PacketConn) SetHopLimit(hoplim int) error
- func (c *PacketConn) SetICMPFilter(f *ICMPFilter) error
- func (c *PacketConn) SetMulticastHopLimit(hoplim int) error
- func (c *PacketConn) SetMulticastInterface(ifi *net.Interface) error
- func (c *PacketConn) SetMulticastLoopback(on bool) error
- func (c *PacketConn) SetReadDeadline(t time.Time) error
- func (c *PacketConn) SetTrafficClass(tclass int) error
- func (c *PacketConn) SetWriteDeadline(t time.Time) error
- func (c *PacketConn) TrafficClass() (int, error)
- func (c *PacketConn) WriteTo(b []byte, cm *ControlMessage, dst net.Addr) (n int, err error)
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Conn ¶
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.
func (*Conn) PathMTU ¶
PathMTU returns a path MTU value for the destination associated with the endpoint.
func (*Conn) SetHopLimit ¶
SetHopLimit sets the hop limit field value for future outgoing packets.
func (*Conn) SetTrafficClass ¶
SetTrafficClass sets the traffic class field value for future outgoing packets.
func (*Conn) TrafficClass ¶
TrafficClass returns the traffic class field value for outgoing packets.
type ControlFlags ¶
type ControlFlags uint
A ControlFlags reprensents 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 ¶
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 (*ControlMessage) String ¶
func (cm *ControlMessage) String() string
type ICMPFilter ¶
type ICMPFilter struct {
// contains filtered or unexported fields
}
An ICMPFilter represents an ICMP message filter for incoming packets.
func (*ICMPFilter) Set ¶
func (f *ICMPFilter) Set(typ ICMPType, block bool)
Set sets the ICMP type and filter action to the filter.
func (*ICMPFilter) SetAll ¶
func (f *ICMPFilter) SetAll(block bool)
SetAll sets the filter action to the filter.
func (*ICMPFilter) WillBlock ¶
func (f *ICMPFilter) WillBlock(typ ICMPType) bool
WillBlock reports whether the ICMP type will be blocked.
type ICMPType ¶
type ICMPType int
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 )
Internet Control Message Protocol version 6 (ICMPv6) Parameters, Updated: 2013-07-03
type PacketConn ¶
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.
func NewPacketConn ¶
func NewPacketConn(c net.PacketConn) *PacketConn
NewPacketConn returns a new PacketConn using c as its underlying transport.
func (*PacketConn) Checksum ¶
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 (*PacketConn) ICMPFilter ¶
func (c *PacketConn) ICMPFilter() (*ICMPFilter, error)
ICMPFilter returns an ICMP filter.
func (*PacketConn) JoinGroup ¶
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 (*PacketConn) LeaveGroup ¶
LeaveGroup leaves the group address group on the interface ifi.
func (*PacketConn) MulticastHopLimit ¶
MulticastHopLimit returns the hop limit field value for outgoing multicast packets.
func (*PacketConn) MulticastInterface ¶
MulticastInterface returns the default interface for multicast packet transmissions.
func (*PacketConn) MulticastLoopback ¶
MulticastLoopback reports whether transmitted multicast packets should be copied and send back to the originator.
func (*PacketConn) ReadFrom ¶
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.
func (*PacketConn) SetChecksum ¶
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 (*PacketConn) SetControlMessage ¶
func (c *PacketConn) SetControlMessage(cf ControlFlags, on bool) error
SetControlMessage allows to receive the per packet basis IP-level socket options.
func (*PacketConn) SetDeadline ¶
func (c *PacketConn) SetDeadline(t time.Time) error
SetDeadline sets the read and write deadlines associated with the endpoint.
func (*PacketConn) SetHopLimit ¶
SetHopLimit sets the hop limit field value for future outgoing packets.
func (*PacketConn) SetICMPFilter ¶
func (c *PacketConn) SetICMPFilter(f *ICMPFilter) error
SetICMPFilter deploys the ICMP filter.
func (*PacketConn) SetMulticastHopLimit ¶
SetMulticastHopLimit sets the hop limit field value for future outgoing multicast packets.
func (*PacketConn) SetMulticastInterface ¶
SetMulticastInterface sets the default interface for future multicast packet transmissions.
func (*PacketConn) SetMulticastLoopback ¶
SetMulticastLoopback sets whether transmitted multicast packets should be copied and send back to the originator.
func (*PacketConn) SetReadDeadline ¶
func (c *PacketConn) SetReadDeadline(t time.Time) error
SetReadDeadline sets the read deadline associated with the endpoint.
func (*PacketConn) SetTrafficClass ¶
SetTrafficClass sets the traffic class field value for future outgoing packets.
func (*PacketConn) SetWriteDeadline ¶
func (c *PacketConn) SetWriteDeadline(t time.Time) error
SetWriteDeadline sets the write deadline associated with the endpoint.
func (*PacketConn) TrafficClass ¶
TrafficClass returns the traffic class field value for outgoing packets.
func (*PacketConn) WriteTo ¶
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.
Source Files