Class: PacketFu::TcpEcn

Inherits:
Struct
  • Object
show all
Includes:
StructFu
Defined in:
lib/packetfu/protos/tcp/ecn.rb

Overview

Implements the Explict Congestion Notification for TCPHeader.

Header Definition

Fixnum (1 bit)  :n
Fixnum (1 bit)  :c
Fixnum (1 bit)  :e

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from StructFu

#body=, #clone, #set_endianness, #sz, #typecast

Methods inherited from Struct

#force_binary

Constructor Details

#initialize(args = {}) ⇒ TcpEcn


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# File 'lib/packetfu/protos/tcp/ecn.rb', line 15

def initialize(args={})
  super(args[:n], args[:c], args[:e]) if args
end

Instance Attribute Details

#cObject

Returns the value of attribute c


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# File 'lib/packetfu/protos/tcp/ecn.rb', line 11

def c
  @c
end

#eObject

Returns the value of attribute e


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# File 'lib/packetfu/protos/tcp/ecn.rb', line 11

def e
  @e
end

#nObject

Returns the value of attribute n


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# File 'lib/packetfu/protos/tcp/ecn.rb', line 11

def n
  @n
end

Instance Method Details

#read(str) ⇒ Object

Reads a string to populate the object.


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# File 'lib/packetfu/protos/tcp/ecn.rb', line 26

def read(str)
  force_binary(str)
  return self if str.nil? || str.size < 2
  if 1.respond_to? :ord
    byte1 = str[0].ord
    byte2 = str[1].ord
  else
    byte1 = str[0]
    byte2 = str[1]
  end
  self[:n] = byte1 & 0b00000001 == 0b00000001 ? 1 : 0
  self[:c] = byte2 & 0b10000000 == 0b10000000 ? 1 : 0
  self[:e] = byte2 & 0b01000000 == 0b01000000 ? 1 : 0
  self
end

#to_iObject

Returns the TcpEcn field as an integer… even though it's going to be split across a byte boundary.


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# File 'lib/packetfu/protos/tcp/ecn.rb', line 21

def to_i
  (n.to_i << 2) + (c.to_i << 1) + e.to_i
end