Class: PacketGen::Header::ARP

Inherits:

Base

• Object
• BinStruct::Struct
• Base
• PacketGen::Header::ARP

Defined in:

lib/packetgen/header/arp.rb

Overview

An ARP header consists of:

• a hardware type (#hrd or #htype) field (BinStruct::Int16),

• a protocol type (#pro or #ptype) field (Int16),

• a hardware address length (#hln or #hlen) field (BinStruct::Int8),

• a protocol address length (#pln or #plen) field (Int8),

• a #opcode (or #op) field (Int16),

• a source hardware address (#sha or #src_mac) field (Eth::MacAddr),

• a source protocol address (#spa or #src_ip) field (IP::Addr),

• a target hardware address (#tha or #dst_mac) field (Eth::MacAddr),

• a target protocol address (#tpa or #dst_ip) field (IP::Addr),

• and a #body.

Examples:

Create a ARP header

# standalone
arp = PacketGen::Header::ARP.new
# in a packet
pkt = PacketGen.gen('Eth').add('ARP')
# access to ARP header
pkt.arp.protocol_name   # => "ARP"

Author:

• Sylvain Daubert

Instance Attribute Summary

• #body ⇒ BinStruct::String, Header::Base
• #hln ⇒ Object (also: #hlen)

  8-bit hardware address length # @return [Integer].

• #hrd ⇒ Object (also: #htype)

  16-bit hardware protocol type # @return [Integer].

• #op ⇒ Object (also: #opcode)

  16-bit operation code # @return [Integer].

• #pln ⇒ Object (also: #plen)

  8-bit internet address length # @return [Integer].

• #pro ⇒ Object (also: #ptype)

  16-bit internet protocol type # @return [Integer].

• #sha ⇒ Eth::MacAddr (also: #src_mac)

  source hardware address.

• #spa ⇒ IP::Addr (also: #src_ip)

  source protocol address.

• #tha ⇒ Eth::MacAddr (also: #dst_mac)

  target hardware address.

• #tpa ⇒ IP::Addr (also: #dst_ip)

  target protocol address.

Instance Method Summary

• #initialize(options = {}) ⇒ ARP constructor

  A new instance of ARP.

• #reply! ⇒ self

  Invert data to create a reply.

Methods inherited from Base

bind, calculate_and_set_length, #header_id, inherited, #ip_header, #ll_header

Methods included from PacketGen::Headerable

#added_to_packet, included, #method_name, #packet, #packet=, #parse?, #protocol_name, #read, #to_s

Constructor Details

#initialize(options = {}) ⇒ ARP

Returns a new instance of ARP.

Parameters:

• options (Hash) (defaults to: {})

Options Hash (options):

• :hrd (Integer) —

  network protocol type (default: 1)

• :pro (Integer) —

  internet protocol type (default: 0x800)

• :hln (Integer) —

  length of hardware addresses (default: 6)

• :pln (Integer) —

  length of internet addresses (default: 4)

• :op (Integer) —

  operation performing by sender (default: 1). known values are request (1) and reply (2)

• :sha (String) —

  sender hardware address

• :spa (String) —

  sender internet address

• :tha (String) —

  target hardware address

• :tpa (String) —

  targetr internet address

# File 'lib/packetgen/header/arp.rb', line 84

def initialize(options={})
  handle_options(options)
  super
end

Instance Attribute Details

#body ⇒ BinStruct::String, Header::Base

Returns:

• (BinStruct::String, Header::Base)

# File 'lib/packetgen/header/arp.rb', line 71

define_attr :body, BinStruct::String

#hln ⇒ Object Also known as: hlen

8-bit hardware address length # @return [Integer]

# File 'lib/packetgen/header/arp.rb', line 44

define_attr :hln, BinStruct::Int8, default: 6

#hrd ⇒ Object Also known as: htype

16-bit hardware protocol type # @return [Integer]

# File 'lib/packetgen/header/arp.rb', line 36

define_attr :hrd, BinStruct::Int16, default: 1

#op ⇒ Object Also known as: opcode

16-bit operation code # @return [Integer]

# File 'lib/packetgen/header/arp.rb', line 52

define_attr :op, BinStruct::Int16Enum, enum: { 'request' => 1, 'reply' => 2 }

#pln ⇒ Object Also known as: plen

8-bit internet address length # @return [Integer]

# File 'lib/packetgen/header/arp.rb', line 48

define_attr :pln, BinStruct::Int8, default: 4

#pro ⇒ Object Also known as: ptype

16-bit internet protocol type # @return [Integer]

# File 'lib/packetgen/header/arp.rb', line 40

define_attr :pro, BinStruct::Int16, default: 0x800

#sha ⇒ Eth::MacAddr Also known as: src_mac

source hardware address

Returns:

• (Eth::MacAddr)

# File 'lib/packetgen/header/arp.rb', line 56

define_attr :sha, Eth::MacAddr

#spa ⇒ IP::Addr Also known as: src_ip

source protocol address

Returns:

• (IP::Addr)

# File 'lib/packetgen/header/arp.rb', line 60

define_attr :spa, IP::Addr

#tha ⇒ Eth::MacAddr Also known as: dst_mac

target hardware address

Returns:

• (Eth::MacAddr)

# File 'lib/packetgen/header/arp.rb', line 64

define_attr :tha, Eth::MacAddr

#tpa ⇒ IP::Addr Also known as: dst_ip

target protocol address

Returns:

• (IP::Addr)

# File 'lib/packetgen/header/arp.rb', line 68

define_attr :tpa, IP::Addr

Instance Method Details

#reply! ⇒ self

Invert data to create a reply.

Returns:

• (self)

# File 'lib/packetgen/header/arp.rb', line 110

def reply!
  case opcode.to_i
  when 1
    self.opcode = 2
    invert_addresses
  when 2
    self.opcode = 1
    invert_addresses
    self[:tha].from_human('00:00:00:00:00:00')
  end
  self
end