ipv4

package
v0.0.0-...-f5c58d3 Latest Latest
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 Go to latest Published: Jul 6, 2016 License: BSD-2-Clause Imports: 13 Imported by: 2

Documentation

Index

Constants

View Source 
const (
	// ARPRequest for ARP requests.
	ARPRequest = 1
	// ARPReply for ARP replies.
	ARPReply = 2
)
View Source 
const (
	// DefaultARPExpiration is the default expiration for entries in the ARP table.
	DefaultARPExpiration = 4 * time.Hour

	// DefaultARPCleanupInterval is the cleanup interval for the cache.
	DefaultARPCleanupInterval = DefaultARPExpiration

	// DefaultARPQueryInterval is the default query interval to use when sending
	// ARP requests.
	DefaultARPQueryInterval = 1 * time.Second

	// DefaultARPTimeout is the default number of ARP requests after which to
	// give up on an ARP request.
	DefaultARPTimeout = 3
)
View Source 
const (
	// ProtocolICMP is used for the ICMP protocol.
	ProtocolICMP = 1

	// ProtocolUDP is used for the UDP protocol.
	ProtocolUDP = 17
)
View Source 
const (
	// ARPHardwareEthernet as lower layer.
	ARPHardwareEthernet = 1
)
View Source 
const (
	// ARPProtocolIPv4 as upper layer.
	ARPProtocolIPv4 = 0x800
)

Variables

View Source 
var (
	// ErrInvalidIHL is a check error returned when the length of the Options
	// byte slice does not match the IHL value.
	ErrInvalidIHL = errors.New("IHL field does not match Options byte slice length")

	// ErrInvalidChecksum is a check error returned when header checksum is
	// incorrect.
	ErrInvalidChecksum = errors.New("Checksum field is incorrect")

	// ErrInvalidTotalLength is an error returned when the packet length is
	// too small.
	ErrInvalidTotalLength = errors.New("TotalLength field is too small")
)
View Source 
var Broadcast = Address([4]byte{255, 255, 255, 255})

Broadcast is the IPv4 broadcast address.

View Source 
var (
	// ErrARPTimeout occurs when no ARP reply is received for an ARP request.
	ErrARPTimeout = errors.New("ARP request timeout")
)
View Source 
var (
	// ErrNoRouteToDestinationAddress is returned when there is no route
	// to the destination address.
	ErrNoRouteToDestinationAddress = errors.New("no route to destination address")
)

Functions

This section is empty.

Types

type ARP 

type ARP interface {
	Resolve(address Address) (ethernet.MAC, error)
}

ARP represents an ARP layer that can convert IPv4 addresses to Ethernet addresses.

func NewARP 

func NewARP(mac ethernet.MAC, ip Address, eth ethernet.Layer) ARP

NewARP will create a default ARP interface with the default configuration.

func NewCustomARP 

func NewCustomARP(mac ethernet.MAC, ip Address, eth ethernet.Layer, expiration, cleanupInterval, queryInterval time.Duration, timeout int) ARP

NewCustomARP will create a default ARP interface with a custom configuration.

type ARPHardwareType 

type ARPHardwareType uint16

ARPHardwareType is the network protocol of the ARP packet.

type ARPOperation 

type ARPOperation uint16

ARPOperation is a type of ARP packet.

type ARPPacket 

type ARPPacket struct {
	HardwareType          ARPHardwareType
	ProtocolType          ARPProtocolType
	HardwareAddressLength uint8
	ProtocolAddressLength uint8
	Operation             ARPOperation
	SenderHardwareAddress ethernet.MAC
	SenderProtocolAddress Address
	TargetHardwareAddress ethernet.MAC
	TargetProtocolAddress Address
}

ARPPacket represents an ARP packet

func NewARPPacket 

func NewARPPacket(r io.Reader) (ARPPacket, error)

NewARPPacket reads an ARP packet from a reader.

func NewARPReply 

func NewARPReply(senderMAC, targetMAC ethernet.MAC, senderIP, targetIP Address) ARPPacket

NewARPReply constructs an ARP reply packet.

func NewARPRequest 

func NewARPRequest(senderMAC ethernet.MAC, senderIP, targetIP Address) ARPPacket

NewARPRequest creates an ARP request packet.

func (ARPPacket) Write 

func (p ARPPacket) Write(w io.Writer) error

Write an ARP packet to a writer.

type ARPProtocolType 

type ARPProtocolType uint16

ARPProtocolType is the internetwork protocol of the ARP packet.

type Address 

type Address [4]byte

Address is an IPv4 address.

func NewAddress 

func NewAddress(s string) (Address, bool)

NewAddress creates a new address from a string.

If the string is invalid, NewAddress returns false.

func (Address) And 

func (a Address) And(b Address) Address

And will perform the logical AND operation on two IP addresses.

func (Address) Bytes 

func (a Address) Bytes() []byte

Bytes copies an address to a new byte slice.

func (Address) Equals 

func (a Address) Equals(b Address) bool

Equals will compare two IP addresses for equality.

func (Address) String 

func (a Address) String() string
type Header struct {
	Version        uint8
	IHL            uint8
	ToS            uint8
	TotalLength    uint16
	Identification uint16
	Flags          uint8
	FragmentOffset uint16
	TTL            uint8
	Protocol       Protocol
	Checksum       uint16
	Source         Address
	Destination    Address
	Options        []byte
}

Header is the logical version of an IPv4 header.

func NewHeader 

func NewHeader(r io.Reader) (Header, error)

NewHeader reads a header from a Reader.

func (Header) CalculateChecksum 

func (h Header) CalculateChecksum() uint16

CalculateChecksum calculates the header checksum.

func (Header) Check 

func (h Header) Check() error

Check checks whether the IPv4 header is valid.

The function fails if the checksum is not correct, or if the IHL field does not match the length of the Options byte slice.

This functions can return ErrInvalidIHL, ErrInvalidChecksum or ErrInvalidTotalLength.

func (Header) RawHeader 

func (h Header) RawHeader() RawHeader

RawHeader converts the header to a RawHeader.

func (Header) Write 

func (h Header) Write(w io.Writer) error

Write the header to a Writer.

type Layer 

type Layer interface {
	Packets(p Protocol) <-chan Packet
	Send(t Packet) error
}

Layer is an IPv4 layer.

func NewLayer 

func NewLayer(address Address, router Router, eth ethernet.Layer) Layer

NewLayer creates a new instance of the default IPv4 layer.

type Packet 

type Packet struct {
	Header
	Payload []byte
}

Packet is an IPv4 packet.

func NewDefaultPacket 

func NewDefaultPacket() Packet

NewDefaultPacket constructs a default IPv4 packet.

func NewPacket 

func NewPacket(r io.Reader) (p Packet, err error)

NewPacket will read a packet from a reader.

The header will be checked using the Check() function. Only valid packets will be returned, unless err is not nil.

func NewPacketTo 

func NewPacketTo(to Address, proto Protocol, payload []byte) Packet

NewPacketTo constructs a new packet with a destination.

func (Packet) String 

func (packet Packet) String() string

func (Packet) Write 

func (packet Packet) Write(w io.Writer) error

Write will write a packet to a writer.

type Protocol 

type Protocol uint8

Protocol is an IPv4 protocol.

type RawHeader 

type RawHeader struct {
	VersionIHL          uint8
	ToS                 uint8
	TotalLength         uint16
	Identification      uint16
	FlagsFragmentOffset uint16
	TTL                 uint8
	Protocol            Protocol
	Checksum            uint16
	Source              Address
	Destination         Address
}

RawHeader represents a raw IPv4 header.

This struct can be written and read with the binary package.

func NewRawHeader 

func NewRawHeader(r io.Reader) (RawHeader, error)

NewRawHeader reads a new raw header from a reader.

func (RawHeader) Header 

func (h RawHeader) Header() Header

Header converts the RawHeader to a logic Header.

func (RawHeader) Write 

func (h RawHeader) Write(w io.Writer) error

Write the header to a Writer.

type Router 

type Router interface {
	// Resolve will resolve the IPv4 address to the ethernet MAC address
	// of the next hop.
	//
	// See also ErrNoRouteToDestinationAddress.
	Resolve(address Address) (ethernet.MAC, error)
}

Router is an IPv4 router.

func NewRouter 

func NewRouter(arp ARP, address, netmask Address, gateway *Address) Router

NewRouter creates a default router.

ARP is used to resolve local addresses. Otherwise, the MAC address of the gateway is returned.

Specifying a gateway is optional.

Source Files

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