Class: PacketGen::Header::ICMP

Inherits:
Base show all
Defined in:
lib/packetgen/header/icmp.rb

Overview

ICMP header (RFC 792)

 0                   1                   2                   3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|     Type      |     Code      |          Checksum             |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

A ICMP header consists of:

Create a ICMP header

# standalone
icmp = PacketGen::Header::ICMP.new
# in a packet
pkt = PacketGen.gen('IP').add('ICMP')
# access to ICMP header
pkt.icmp     # => PacketGen::Header::ICMP

ICMP attributes

icmp.code = 0
icmp.type = 200
icmp.checksum = 0x248a
icmp.body.read 'this is a body'

Author:

  • Sylvain Daubert

Direct Known Subclasses

ICMPv6

Constant Summary collapse

IP_PROTOCOL =

ICMP internet protocol number

1

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods inherited from Base

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

Methods included from PacketGen::Headerable

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

Methods inherited from Types::Fields

#[], #[]=, #bits_on, define_bit_fields_on, define_field, define_field_after, define_field_before, #fields, fields, inherited, #initialize, #inspect, #offset_of, #optional?, #optional_fields, #present?, #read, remove_bit_fields_on, remove_field, #sz, #to_h, #to_s, update_field

Constructor Details

This class inherits a constructor from PacketGen::Header::Base

Instance Attribute Details

#body ⇒ Types::String, Header::Base

Returns:



54
 
# File 'lib/packetgen/header/icmp.rb', line 54

define_field :body, Types::String

#checksum ⇒ Integer

16-bit ICMP checksum

Returns:

  • (Integer) 


51
 
# File 'lib/packetgen/header/icmp.rb', line 51

define_field :checksum, Types::Int16

#code ⇒ Integer

8-bit ICMP code

Returns:

  • (Integer) 


47
 
# File 'lib/packetgen/header/icmp.rb', line 47

define_field :code, Types::Int8

#type ⇒ Integer

8-bit ICMP type

Returns:

  • (Integer) 


43
 
# File 'lib/packetgen/header/icmp.rb', line 43

define_field :type, Types::Int8

Instance Method Details

#calc_checksum ⇒ Integer

Compute checksum and set checksum field

Returns:

  • (Integer) 


58
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61
 
# File 'lib/packetgen/header/icmp.rb', line 58

def calc_checksum
  sum = IP.sum16(self)
  self.checksum = IP.reduce_checksum(sum)
end