Class: PacketGen::Header::IP::Option

Inherits:
Types::Fields show all
Includes:
Types::Fieldable
Defined in:
lib/packetgen/header/ip/option.rb

Overview

Base class for IP options

Author:

  • Sylvain Daubert

Direct Known Subclasses

EOL, LSRR, RA, SI

Constant Summary collapse

EOL_TYPE =

EOL option type

0x00
NOP_TYPE =

NOP option type

0x01
LSRR_TYPE =

LSRR option type

0x83
SSRR_TYPE =

SSRR option type

0x84
RR_TYPE =

RR option type

0x07
SI_TYPE =

SI option type

0x88
RA_TYPE =

RA option type

0x94

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Types::Fieldable

#format_inspect, #read, #sz, #type_name

Methods inherited from Types::Fields

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

Constructor Details

#initialize(options = {}) ⇒ Option

Returns a new instance of Option.


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# File 'lib/packetgen/header/ip/option.rb', line 101

def initialize(options={})
  unless options[:type]
    opt_name = self.class.to_s.gsub(/.*::/, '')
    options[:type] = Option.const_get("#{opt_name}_TYPE") if Option.const_defined? "#{opt_name}_TYPE"
  end
  super
  self.length = sz if respond_to?(:length) && options[:length].nil?
end

Instance Attribute Details

#copied ⇒ Boolean

1-bit copied flag from #type field

Returns:

  • (Boolean) 

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# File 'lib/packetgen/header/ip/option.rb', line 70

define_bit_fields_on :type, :copied, :option_class, 2, :number, 5

#data ⇒ Object

option data


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# File 'lib/packetgen/header/ip/option.rb', line 57

define_field :data, Types::String, optional: ->(h) { h.length > 2 },
builder: ->(h, t) { t.new(length_from: -> { h.length - 2 }) }

#length ⇒ Object

8-bit option length. If 0, there is no length field in option


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# File 'lib/packetgen/header/ip/option.rb', line 53

define_field :length, Types::Int8, default: 0, optional: ->(h) { h.type > 1 }

#option_class ⇒ Integer

2-bit option class (0: control, 2: debug and measurement, 1 and 3: reserved) from #type field

Returns:

  • (Integer) 

70
 
# File 'lib/packetgen/header/ip/option.rb', line 70

define_bit_fields_on :type, :copied, :option_class, 2, :number, 5

#type ⇒ Object

8-bit option type


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# File 'lib/packetgen/header/ip/option.rb', line 49

define_field :type, Types::Int8

Class Method Details

.build(options = {}) ⇒ Option

Factory to build an option from its type

Returns:


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# File 'lib/packetgen/header/ip/option.rb', line 88

def self.build(options={})
  type = options.delete(:type)
  klass = case type
          when String
            types.key?(type) ? IP.const_get(type) : self
          when Integer
            types.value?(type) ? IP.const_get(types.key(type)) : self
          else
            self
          end
  klass.new(options)
end

.types ⇒ Hash

Returns:

  • (Hash) 

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# File 'lib/packetgen/header/ip/option.rb', line 73

def self.types
  return @types if defined? @types

  @types = {}
  Option.constants.each do |cst|
    next unless cst.to_s.end_with? '_TYPE'

    optname = cst.to_s.sub(/_TYPE/, '')
    @types[optname] = Option.const_get(cst)
  end
  @types
end

Instance Method Details

#to_human ⇒ String

Get a human readable string

Returns:

  • (String) 

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# File 'lib/packetgen/header/ip/option.rb', line 119

def to_human
  str = self.instance_of?(Option) ? +"unk-#{type}" : self.class.to_s.sub(/.*::/, '')
  str << ":#{self[:data].to_s.inspect}" if respond_to?(:length) && (length > 2) && !self[:data].to_s.empty?
  str
end

#to_s ⇒ String

Get binary string. Set #length field.

Returns:

  • (String) 

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# File 'lib/packetgen/header/ip/option.rb', line 112

def to_s
  self.length = super.size if respond_to? :length
  super
end