lib/packetgen/header/tcp.rb in packetgen-2.4.0 vs lib/packetgen/header/tcp.rb in packetgen-2.5.0

@@ -1,15 +1,22 @@
+# This file is part of PacketGen
+# See https://github.com/sdaubert/packetgen for more informations
+# Copyright (C) 2016 Sylvain Daubert <[e-mail]>
+# This program is published under MIT license.
+
+# frozen_string_literal: true
+
 module PacketGen
   module Header
 
     # A TCP header consists of:
     # * a source port ({#sport}, {Types::Int16} type),
     # * a destination port ({#dport}, +Int16+ type),
     # * a sequence number ({#seqnum}, {Types::Int32} type),
     # * an acknownledge number ({#acknum}, +Int32+ type),
     # * a 16-bit field ({#u16}, +Int16+ type) composed of:
-    #   * a 4-bit {#data_offset} value,
+    #   * a 4-bit {#data_offset} self[attr],
     #   * a 3-bit {#reserved} field,
     #   * a 9-bit {#flags} field,
     # * a {#window} field (+Int16+ type),
     # * a {#checksum} field (+Int16+ type),
     # * a urgent pointer ({#urg_pointer}, +Int16+ type),
@@ -42,11 +49,11 @@
     #
     # == Options
     # {#options} TCP attribute is a {Options}. {Option} may added to it:
     #  tcph.options << PacketGen::Header::TCP::MSS.new(1250)
     # or:
-    #  tcph.options << { opt: 'MSS', value: 1250 }
+    #  tcph.options << { opt: 'MSS', self[attr]: 1250 }
     # @author Sylvain Daubert
     class TCP < Base
     end
   end
 end
@@ -186,19 +193,12 @@
       # @return [Integer]
       def calc_checksum
         sum = ip_header(self).pseudo_header_checksum
         sum += IP_PROTOCOL
         sum += self.sz
-        str = self.to_s
-        str << "\x00" if str.length % 2 == 1
-        sum += str.unpack('n*').reduce(:+)
-
-        while sum > 0xffff do
-          sum = (sum & 0xffff) + (sum >> 16)
-        end
-        sum = ~sum & 0xffff
-        self[:checksum].value = (sum == 0) ? 0xffff : sum
+        sum += IP.sum16(self)
+        self.checksum = IP.reduce_checksum(sum)
       end
 
       # Compute header length and set +data_offset+ field
       # @return [Integer]
       def calc_length
@@ -210,17 +210,17 @@
 
       # @return [String]
       def inspect
         str = Inspect.dashed_line(self.class, 2)
         shift = Inspect.shift_level(2)
-        to_h.each do |attr, value|
+        fields.each do |attr|
           next if attr == :body
-          str << Inspect.inspect_attribute(attr, value, 2)
+          str << Inspect.inspect_attribute(attr, self[attr], 2)
           if attr == :u16
             doff = Inspect.int_dec_hex(data_offset, 1)
             str << shift + Inspect::FMT_ATTR % ['', 'data_offset', doff]
             str << shift + Inspect::FMT_ATTR % ['', 'reserved', reserved]
-            flags = ''
+            flags = ''.dup
             %w(ns cwr ece urg ack psh rst syn fin).each do |fl|
               flags << (send("flag_#{fl}?") ? fl[0].upcase : '.')
             end
             str << shift + Inspect::FMT_ATTR % ['', 'flags', flags]
           end