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

Inherits:
BinStruct::Struct
  • Object
show all
Includes:
BinStruct::Structable
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

Constructor Details

#initialize(options = {}) ⇒ Option

Force type value for subclasses, if not specified



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# File 'lib/packetgen/header/ip/option.rb', line 108

def initialize(options={})
  options[:type] = class2type unless options[:type]

  super
  initialize_length_if_needed(options)
  initialize_data_if_needed(options)
end

Instance Attribute Details

#copied ⇒ Integer

1-bit copied flag from #type field

Returns:

  • (Integer) 


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

define_bit_attr :type, copied: 1, option_class: 2, number: 5

#data ⇒ String

option data

Returns:

  • (String) 


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# File 'lib/packetgen/header/ip/option.rb', line 72

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

#length ⇒ Integer

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

Returns:

  • (Integer) 


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

define_attr :length, BinStruct::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) 


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

define_bit_attr :type, copied: 1, option_class: 2, number: 5

#type ⇒ Integer

8-bit option type

Returns:

  • (Integer) 


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

define_bit_attr :type, copied: 1, option_class: 2, number: 5

Class Method Details

.build(options = {}) ⇒ Option

Factory to build an option from its type

Parameters:

  • options (Hash) (defaults to: {})

Returns:



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# File 'lib/packetgen/header/ip/option.rb', line 94

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

.types ⇒ Hash{String => Integer}

Return a cached hash associating type name to its value.

Returns:

  • (Hash{String => Integer}) 


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# File 'lib/packetgen/header/ip/option.rb', line 78

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 125

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 118

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