Class: PacketGen::PcapNG::EPB

Inherits:
Block show all
Defined in:
lib/packetgen/pcapng/epb.rb

Overview

EPB represents a Enhanced Packet Block (EPB) of a pcapng file.

EPB Definition

Int32   :type           Default: 0x00000006
Int32   :block_len
Int32   :interface_id
Int32   :tsh (timestamp high)
Int32   :tsl (timestamp low)
Int32   :cap_len
Int32   :orig_len
String  :data
String  :options
Int32   :block_len2

Author:

  • Sylvain Daubert

Constant Summary collapse

MIN_SIZE =

Minimum EPB size

8 * 4

Instance Attribute Summary collapse

Attributes inherited from Block

#block_len, #type

Instance Method Summary collapse

Methods inherited from Block

#has_options?, #options?, #pad_field, #recalc_block_len

Methods inherited from Types::Fields

#[], #[]=, #bits_on, #body=, define_bit_fields_on, define_field, define_field_after, define_field_before, delete_field, fields, #fields, #force_binary, inherited, #inspect, #is_optional?, #is_present?, #offset_of, #optional?, #optional_fields, #present?, remove_bit_fields_on, remove_field, #sz, #to_h, update_field

Constructor Details

#initialize(options = {}) ⇒ EPB

Returns a new instance of EPB.

Options Hash (options):

  • :endian (:little, :big) —

    set block endianness

  • :type (Integer)
  • :block_len (Integer) —

    block total length

  • :interface_id (Integer) —

    specifies the interface this packet comes from

  • :tsh (Integer) —

    timestamp (high nibbles)

  • :tsl (Integer) —

    timestamp (low nibbles)

  • :cap_len (Integer) —

    number of octets captured from the packet

  • :orig_len (Integer) —

    actual length of the packet when it was transmitted on the network

  • :data (::String)
  • :options (::String)
  • :block_len2 (Integer) —

    block total length



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# File 'lib/packetgen/pcapng/epb.rb', line 74

def initialize(options={})
  super
  set_endianness(options[:endian] || :little)
  recalc_block_len
  self.type = options[:type] || PcapNG::EPB_TYPE.to_i
end

Instance Attribute Details

#cap_len ⇒ Integer

32-bit capture length



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# File 'lib/packetgen/pcapng/epb.rb', line 48

define_field_before :block_len2, :cap_len, Types::Int32, default: 0

#data ⇒ Types::String 



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# File 'lib/packetgen/pcapng/epb.rb', line 55

define_field_before :block_len2, :data, Types::String

#endian ⇒ :little, :big 



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# File 'lib/packetgen/pcapng/epb.rb', line 29

def endian
  @endian
end

#interface ⇒ IPB 



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# File 'lib/packetgen/pcapng/epb.rb', line 31

def interface
  @interface
end

#interface_id ⇒ Integer

32-bit interface ID



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# File 'lib/packetgen/pcapng/epb.rb', line 36

define_field_before :block_len2, :interface_id, Types::Int32, default: 0

#options ⇒ Types::String 



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# File 'lib/packetgen/pcapng/epb.rb', line 58

define_field_before :block_len2, :options, Types::String

#orig_len ⇒ Integer

32-bit original length



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# File 'lib/packetgen/pcapng/epb.rb', line 52

define_field_before :block_len2, :orig_len, Types::Int32, default: 0

#tsh ⇒ Integer

high 32-bit timestamp value



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# File 'lib/packetgen/pcapng/epb.rb', line 40

define_field_before :block_len2, :tsh, Types::Int32, default: 0

#tsl ⇒ Integer

low 32-bit imestamp value



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# File 'lib/packetgen/pcapng/epb.rb', line 44

define_field_before :block_len2, :tsl, Types::Int32, default: 0

Instance Method Details

#read(str_or_io) ⇒ self

Reads a String or a IO to populate the object



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# File 'lib/packetgen/pcapng/epb.rb', line 84

def read(str_or_io)
  io = if str_or_io.respond_to? :read
         str_or_io
       else
         StringIO.new(force_binary(str_or_io.to_s))
       end
  return self if io.eof?

  self[:type].read io.read(4)
  self[:block_len].read io.read(4)
  self[:interface_id].read io.read(4)
  self[:tsh].read io.read(4)
  self[:tsl].read io.read(4)
  self[:cap_len].read io.read(4)
  self[:orig_len].read io.read(4)
  self[:data].read io.read(self[:cap_len].to_i)
  data_pad_len = (4 - (self[:cap_len].to_i % 4)) % 4
  io.read data_pad_len
  options_len = self[:block_len].to_i - self[:cap_len].to_i - data_pad_len
  options_len -= MIN_SIZE
  self[:options].read io.read(options_len)
  self[:block_len2].read io.read(4)

  check_len_coherency
  self
end

#timestamp ⇒ Time

Return timestamp as a Time object



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# File 'lib/packetgen/pcapng/epb.rb', line 113

def timestamp
  Time.at((self[:tsh].to_i << 32 | self[:tsl].to_i) * ts_resol)
end

#to_s ⇒ String

Return the object as a String



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# File 'lib/packetgen/pcapng/epb.rb', line 119

def to_s
  pad_field :data, :options
  recalc_block_len
  super
end