Class: Resolv::DNS::Message::MessageDecoder

Inherits:
Object
  • Object
show all
Defined in:
lib/resolv.rb

Overview

:nodoc:

Instance Method Summary collapse

Constructor Details

#initialize(data) {|_self| ... } ⇒ MessageDecoder

Returns a new instance of MessageDecoder.

Yields:

  • (_self)

Yield Parameters:


1548
1549
1550
1551
1552
1553
# File 'lib/resolv.rb', line 1548

def initialize(data)
  @data = data
  @index = 0
  @limit = data.bytesize
  yield self
end

Instance Method Details

#get_bytes(len = @limit - @index) ⇒ Object

Raises:


1573
1574
1575
1576
1577
1578
# File 'lib/resolv.rb', line 1573

def get_bytes(len = @limit - @index)
  raise DecodeError.new("limit exceeded") if @limit < @index + len
  d = @data.byteslice(@index, len)
  @index += len
  return d
end

#get_labelObject


1651
1652
1653
# File 'lib/resolv.rb', line 1651

def get_label
  return Label::Str.new(self.get_string)
end

#get_labelsObject


1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
# File 'lib/resolv.rb', line 1622

def get_labels
  prev_index = @index
  save_index = nil
  d = []
  while true
    raise DecodeError.new("limit exceeded") if @limit <= @index
    case @data.getbyte(@index)
    when 0
      @index += 1
      if save_index
        @index = save_index
      end
      return d
    when 192..255
      idx = self.get_unpack('n')[0] & 0x3fff
      if prev_index <= idx
        raise DecodeError.new("non-backward name pointer")
      end
      prev_index = idx
      if !save_index
        save_index = @index
      end
      @index = idx
    else
      d << self.get_label
    end
  end
end

#get_length16Object


1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
# File 'lib/resolv.rb', line 1559

def get_length16
  len, = self.get_unpack('n')
  save_limit = @limit
  @limit = @index + len
  d = yield(len)
  if @index < @limit
    raise DecodeError.new("junk exists")
  elsif @limit < @index
    raise DecodeError.new("limit exceeded")
  end
  @limit = save_limit
  return d
end

#get_nameObject


1618
1619
1620
# File 'lib/resolv.rb', line 1618

def get_name
  return Name.new(self.get_labels)
end

#get_questionObject


1655
1656
1657
1658
1659
# File 'lib/resolv.rb', line 1655

def get_question
  name = self.get_name
  type, klass = self.get_unpack("nn")
  return name, Resource.get_class(type, klass)
end

#get_rrObject


1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
# File 'lib/resolv.rb', line 1661

def get_rr
  name = self.get_name
  type, klass, ttl = self.get_unpack('nnN')
  typeclass = Resource.get_class(type, klass)
  res = self.get_length16 do
    begin
      typeclass.decode_rdata self
    rescue => e
      raise DecodeError, e.message, e.backtrace
    end
  end
  res.instance_variable_set :@ttl, ttl
  return name, ttl, res
end

#get_stringObject

Raises:


1601
1602
1603
1604
1605
1606
1607
1608
# File 'lib/resolv.rb', line 1601

def get_string
  raise DecodeError.new("limit exceeded") if @limit <= @index
  len = @data.getbyte(@index)
  raise DecodeError.new("limit exceeded") if @limit < @index + 1 + len
  d = @data.byteslice(@index + 1, len)
  @index += 1 + len
  return d
end

#get_string_listObject


1610
1611
1612
1613
1614
1615
1616
# File 'lib/resolv.rb', line 1610

def get_string_list
  strings = []
  while @index < @limit
    strings << self.get_string
  end
  strings
end

#get_unpack(template) ⇒ Object

Raises:


1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
# File 'lib/resolv.rb', line 1580

def get_unpack(template)
  len = 0
  template.each_byte {|byte|
    byte = "%c" % byte
    case byte
    when ?c, ?C
      len += 1
    when ?n
      len += 2
    when ?N
      len += 4
    else
      raise StandardError.new("unsupported template: '#{byte.chr}' in '#{template}'")
    end
  }
  raise DecodeError.new("limit exceeded") if @limit < @index + len
  arr = @data.unpack("@#{@index}#{template}")
  @index += len
  return arr
end

#inspectObject


1555
1556
1557
# File 'lib/resolv.rb', line 1555

def inspect
  "\#<#{self.class}: #{@data.byteslice(0, @index).inspect} #{@data.byteslice(@index..-1).inspect}>"
end