Class: ReDNS::Message

Inherits:
Fragment show all
Defined in:
lib/redns/message.rb

Constant Summary collapse

SECTIONS =

Constants ============================================================

[ :questions, :answers, :nameservers, :additional_records ].freeze

Instance Attribute Summary

Attributes inherited from Fragment

#attributes

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Fragment

attribute, #initialize

Methods included from Support

#addr_to_arpa, #bind_all_addr, #default_nameservers, #default_resolver_address, #dns_port, #inet_aton, #inet_ntoa, #io_nonblock, #io_nonblock?, #io_set_nonblock, #is_ip?

Constructor Details

This class inherits a constructor from ReDNS::Fragment

Class Method Details

.question(name, qtype = nil) {|message| ... } ⇒ Object

Constructs a question that asks for more information about a given resource with an optional query type specified. Query type defaults to :ptr for dotted-quad IP addresses, :a otherwise.

Yields:

  • (message) 


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# File 'lib/redns/message.rb', line 34

def self.question(name, qtype = nil)
  if (!qtype)
    if (ReDNS::Support.is_ip?(name))
      name = ReDNS::Support.addr_to_arpa(name)
      qtype = :ptr
    else
      qtype = :a
    end
  end
  
  message = new(
    :questions => [
      ReDNS::Question.new(
        :name => name,
        :qtype => qtype
      )
    ]
  )
  
  yield(message) if (block_given?)
  
  message
end

Instance Method Details

#deserialize(buffer) ⇒ Object

Extracts a message from the supplied buffer. Will return the message if successful, nil if an error occurred or no suitable data cound be found in the buffer.



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# File 'lib/redns/message.rb', line 145

def deserialize(buffer)
  return unless (buffer)
  
	data = buffer.unpack("nnnnnn")
	
	# Abandon efforts to decode if insufficient data is available.
	return if (data.length < 6)
	
	self.id = data.shift

	flags = data.shift
	self.query = (flags & 0x8000 == 0)
	self.opcode = ReDNS::OPCODE_LABEL[(flags & 0x7800) >> 12]
	self.authorative = (flags & 0x0400 != 0)
	self.truncated = (flags & 0x0200 != 0)
	self.recursion_desired = (flags & 0x0100 != 0)
	self.recursion_available = (flags & 0x0080 != 0)
	self.response_code = ReDNS::RCODE_LABEL[flags & 0x000F]
	
	SECTIONS.each do |section|
	  @attributes[:"#{section}_count"] = data.shift
  end
	
	SECTIONS.each do |section|
	  collection = @attributes[section] = [ ]
	  
	  decode_class =
 		  case (section)
 	    when :questions
 	      ReDNS::Question
      else
        ReDNS::Resource
       end
       
	  @attributes[:"#{section}_count"].times do
	    collection << decode_class.new(buffer)
    end
  end
  
  self
end

#empty? ⇒ Boolean

Returns true if the questions, answers, nameservers and additional records are all empty, false otherwise.

Returns:

  • (Boolean) 


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# File 'lib/redns/message.rb', line 100

def empty?
	questions.empty? and
	  answers.empty? and
	  nameservers.empty? and
	  additional_records.empty?
end

#increment_id! ⇒ Object

Instance Methods =====================================================



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# File 'lib/redns/message.rb', line 60

def increment_id!
  self.id = (self.id + 1) % 0x10000
end

#length ⇒ Object

Returns the length of the encoded DNS request.



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# File 'lib/redns/message.rb', line 94

def length
	to_dns.length
end

#response? ⇒ Boolean

Returns true if this is a response type message, false otherwise, as is the case with query messages.

Returns:

  • (Boolean) 


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# File 'lib/redns/message.rb', line 66

def response?
  !self.query?
end

#serialize(buffer = ReDNS::Buffer.new) ⇒ Object

Serializes the message into a supplied buffer, or allocates a new one to store it. Returns the buffer used.



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# File 'lib/redns/message.rb', line 114

def serialize(buffer = ReDNS::Buffer.new)
  buffer.pack(
	  'nnnnnn',
		self.id,
		(
 			(self.query? ? 0 : 0x8000) |
 			(ReDNS::OPCODE[self.opcode] || ReDNS::OPCODE[:unknown]) << 12 |
 			(self.authorative? ? 0x0400 : 0) |
 			(self.truncated? ? 0x0200 : 0) |
 			(self.recursion_desired? ? 0x0100 : 0) |
 			(self.recursion_available? ? 0x0080 : 0) |
 			(ReDNS::RCODE[self.response_code] || ReDNS::RCODE[:noerror])
		),
	  self.questions.length,
		self.answers.length,
		self.nameservers.length,
		self.additional_records.length
 	)

   [ :questions, :answers, :nameservers, :additional_records ].each do |section|
     @attributes[section] and @attributes[section].each do |part|
       part.serialize(buffer)
     end
   end
   
   buffer
end

#to_s ⇒ Object

Returns a string representation of the message in a format similar to what the dig shell utility produces.



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# File 'lib/redns/message.rb', line 72

def to_s
  flags = [ ]
  flags << 'qr' if (response?)
  flags << 'aa' if (authorative?)
  flags << 'tc' if (truncated?)
  flags << 'rd' if (recursion_desired?)
  flags << 'ra' if (recursion_available?)
  
	";; HEADER:\n;; opcode: #{opcode.to_s.upcase} status: #{response_code.to_s.upcase} id: #{id} \n" +
	";; flags: #{flags.join(' ')}; QUERY: #{questions.length}, ANSWER: #{answers.length}, AUTHORITY: #{nameservers.length}, ADDITIONAL: #{additional_records.length}" +
	"\n" +
	";; QUESTION SECTION:\n" +
	questions.collect(&:to_s).join("\n") + "\n" +
	";; ANSWER SECTION:\n" +
	answers.collect(&:to_s).join("\n") + "\n" +
	";; NAMESERVER SECTION:\n" +
	nameservers.collect(&:to_s).join("\n") + "\n" +
	";; ADDITIONAL SECTION:\n" +
	additional_records.collect(&:to_s).join("\n") + "\n"
end

#to_yaml ⇒ Object

Returns a YAML serialized version of the message.



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# File 'lib/redns/message.rb', line 108

def to_yaml
	@attributes.to_yaml
end