Class: PacketGen::Header::ARP

Inherits:

Struct

• Object
• Struct
• PacketGen::Header::ARP

Extended by:

HeaderClassMethods

Includes:

HeaderMethods, StructFu

Defined in:

lib/packetgen/header/arp.rb

Overview

An ARP header consists of:

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

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

• a hardware address length (#hln or #hlen) field (StructFu::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.

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   # => PacketGen::Header::ARP

Author:

• Sylvain Daubert

Instance Attribute Summary

• #body ⇒ Object

  Returns the value of attribute body.

• #hln ⇒ Integer (also: #hlen)
• #hrd ⇒ Integer (also: #htype)
• #op ⇒ Integer (also: #opcode)
• #pln ⇒ Integer (also: #plen)
• #pro ⇒ Integer (also: #ptype)
• #sha ⇒ String (also: #src_mac)
• #spa ⇒ String (also: #src_ip)
• #tha ⇒ String (also: #dst_mac)
• #tpa ⇒ String (also: #dst_ip)

Instance Method Summary

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

  A new instance of ARP.

• #read(str) ⇒ self

  Read a ARP header from a string.

Methods included from HeaderClassMethods

bind_header, define_bit_fields_on, known_headers

Methods included from HeaderMethods

#header_id, #inspect, #ip_header, #packet, #packet=, #protocol_name

Methods included from StructFu

#clone, #set_endianness, #sz, #to_s, #typecast

Methods inherited from Struct

#force_binary

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 47

def initialize(options={})
  super Int16.new(options[:hrd] || options[:htype] || 1),
        Int16.new(options[:pro] || options[:ptype] || 0x800),
        Int8.new(options[:hln] || options[:hlen] || 6),
        Int8.new(options[:pln] || options[:plen] || 4),
        Int16.new(options[:op] || options[:opcode] || 1),
        Eth::MacAddr.new.from_human(options[:sha] || options[:src_mac]),
        IP::Addr.new.from_human(options[:spa] || options[:src_ip]),
        Eth::MacAddr.new.from_human(options[:tha] || options[:dst_mac]),
        IP::Addr.new.from_human(options[:tpa] || options[:dst_ip]),
        StructFu::String.new.read(options[:body])
end

Instance Attribute Details

#body ⇒ Object

Returns the value of attribute body

Returns:

• (Object) —

  the current value of body

# File 'lib/packetgen/header/arp.rb', line 30

def body
  @body
end

#hln ⇒ Integer Also known as: hlen

Returns:

• (Integer)

# File 'lib/packetgen/header/arp.rb', line 30

def hln
  @hln
end

#hrd ⇒ Integer Also known as: htype

Returns:

• (Integer)

# File 'lib/packetgen/header/arp.rb', line 30

def hrd
  @hrd
end

#op ⇒ Integer Also known as: opcode

Returns:

• (Integer)

# File 'lib/packetgen/header/arp.rb', line 30

def op
  @op
end

#pln ⇒ Integer Also known as: plen

Returns:

• (Integer)

# File 'lib/packetgen/header/arp.rb', line 30

def pln
  @pln
end

#pro ⇒ Integer Also known as: ptype

Returns:

• (Integer)

# File 'lib/packetgen/header/arp.rb', line 30

def pro
  @pro
end

#sha ⇒ String Also known as: src_mac

Returns:

• (String)

# File 'lib/packetgen/header/arp.rb', line 30

def sha
  @sha
end

#spa ⇒ String Also known as: src_ip

Returns:

• (String)

# File 'lib/packetgen/header/arp.rb', line 30

def spa
  @spa
end

#tha ⇒ String Also known as: dst_mac

Returns:

• (String)

# File 'lib/packetgen/header/arp.rb', line 30

def tha
  @tha
end

#tpa ⇒ String Also known as: dst_ip

Returns:

• (String)

# File 'lib/packetgen/header/arp.rb', line 30

def tpa
  @tpa
end

Instance Method Details

#read(str) ⇒ self

Read a ARP header from a string

Parameters:

• str (String) —

  binary string

Returns:

• (self)

Raises:

• (ParseError)

# File 'lib/packetgen/header/arp.rb', line 63

def read(str)
  force_binary str
  raise ParseError, 'string too short for ARP' if str.size < self.sz
  self[:hrd].read str[0, 2]
  self[:pro].read str[2, 2]
  self[:hln].read str[4, 1]
  self[:pln].read str[5, 1]
  self[:op].read str[6, 2]
  self[:sha].read str[8, 6]
  self[:spa].read str[14, 4]
  self[:tha].read str[18, 6]
  self[:tpa].read str[24, 4]
  self[:body].read str[28..-1]
end