Class: Dnsruby::Message

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

Overview

Defines a DNS packet.

RFC 1035 Section 4.1, RFC 2136 Section 2, RFC 2845

Sections

Message objects have five sections:

  • The header section, a Dnsruby::Header object.

    msg.header=Header.new(...)
header = msg.header

  • The question section, an array of Dnsruby::Question objects.

    msg.add_question(Question.new(domain, type, klass))
msg.each_question do |question|  ....   end

  • The answer section, an array of Dnsruby::RR objects.

    msg.add_answer(RR.create({:name    => "a2.example.com",

:type => “A”, :address => “10.0.0.2”}))

msg.each_answer {|answer| ... }

  • The authority section, an array of Dnsruby::RR objects.

    msg.add_authority(rr)
msg.each_authority {|rr| ... }

  • The additional section, an array of Dnsruby::RR objects.

    msg.add_additional(rr)
msg.each_additional {|rr| ... }

In addition, each_resource iterates the answer, additional and authority sections :

msg.each_resource {|rr| ... }

Packet format encoding

Dnsruby::Message#encode
Dnsruby::Message::decode(data)

Direct Known Subclasses

Update

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(*args) ⇒ Message

Create a new Message. Takes optional name, type and class

type defaults to A, and klass defaults to IN

  • Dnsruby::Message.new(“example.com”) # defaults to A, IN

  • Dnsruby::Message.new(“example.com”, ‘AAAA’)

  • Dnsruby::Message.new(“example.com”, Dnsruby::Types.PTR, “HS”)



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# File 'lib/Dnsruby/message.rb', line 70

def initialize(*args)
  @header = Header.new()
  @question = []
  @answer = []
  @authority = []
  @additional = []
  @tsigstate = :Unsigned
  @signing = false
  @tsigkey = nil
  @answerfrom = nil
  type = Types.A
  klass = Classes.IN
  if (args.length > 0)
    name = args[0]
    if (args.length > 1)
      type = Types.new(args[1])
      if (args.length > 2)
        klass = Classes.new(args[2])
      end
    end
    add_question(name, type, klass)
  end
end

Instance Attribute Details

#additional ⇒ Object (readonly)

The additional section, an array of Dnsruby::RR objects.



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# File 'lib/Dnsruby/message.rb', line 102

def additional
  @additional
end

#answer ⇒ Object (readonly) Also known as: pre

The answer section, an array of Dnsruby::RR objects.



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# File 'lib/Dnsruby/message.rb', line 98

def answer
  @answer
end

#answerfrom ⇒ Object

If this Message is a response from a server, then answerfrom contains the address of the server



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# File 'lib/Dnsruby/message.rb', line 107

def answerfrom
  @answerfrom
end

#answersize ⇒ Object

If this Message is a response from a server, then answersize contains the size of the response



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# File 'lib/Dnsruby/message.rb', line 110

def answersize
  @answersize
end

#authority ⇒ Object (readonly) Also known as: update

The authority section, an array of Dnsruby::RR objects.



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

def authority
  @authority
end

#header ⇒ Object

The header section, a Dnsruby::Header object.



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# File 'lib/Dnsruby/message.rb', line 104

def header
  @header
end

#question ⇒ Object (readonly) Also known as: zone

The question section, an array of Dnsruby::Question objects.



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# File 'lib/Dnsruby/message.rb', line 95

def question
  @question
end

#tsigerror ⇒ Object

If this message has been verified using a TSIG RR then tsigerror contains the error code returned by the TSIG verification. The error will be an RCode



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

def tsigerror
  @tsigerror
end

#tsigstart ⇒ Object

–



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# File 'lib/Dnsruby/message.rb', line 126

def tsigstart
  @tsigstart
end

#tsigstate ⇒ Object

Can be

  • :Unsigned - the default state

  • :Signed - the outgoing message has been signed

  • :Verified - the incoming message has been verified

  • :Intermediate - the incoming message is an intermediate envelope in a TCP session

in which only every 100th envelope must be signed

  • :Failed - the incoming response failed verification



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# File 'lib/Dnsruby/message.rb', line 123

def tsigstate
  @tsigstate
end

Class Method Details

.decode(m) ⇒ Object

Decode the encoded message



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# File 'lib/Dnsruby/message.rb', line 337

def Message.decode(m)
  o = Message.new()
  MessageDecoder.new(m) {|msg|
    o.header = Header.new(msg)
    o.header.qdcount.times {
      question = msg.get_question
      o.question << question
    }
    o.header.ancount.times {
      rr = msg.get_rr
      o.answer << rr
    }
    o.header.nscount.times {
      rr = msg.get_rr
      o.authority << rr
    }
    o.header.arcount.times { |count|
      start = msg.index
      rr = msg.get_rr
      if (rr.type == Types.TSIG)
        if (count!=o.header.arcount-1)
          TheLog.Error("Incoming message has TSIG record before last record")
          raise DecodeError.new("TSIG record present before last record")
        end
        o.tsigstart = start # needed for TSIG verification
      end
      o.additional << rr
    }
  }
  return o
end

Instance Method Details

#==(other) ⇒ Object

++



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# File 'lib/Dnsruby/message.rb', line 129

def ==(other)
  ret = false
  if (other.kind_of?Message)
    ret = @header == other.header &&
      @question == other.question &&
      @answer == other.answer &&
      @authority == other.authority &&
      @additional == other.additional
  end
  return ret
end

#add_additional(rr) ⇒ Object

:nodoc: all



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# File 'lib/Dnsruby/message.rb', line 188

def add_additional(rr) #:nodoc: all
  if (!@additional.include?rr)
    @additional << rr
    @header.arcount = @additional.length
  end
end

#add_answer(rr) ⇒ Object Also known as: add_pre

:nodoc: all



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# File 'lib/Dnsruby/message.rb', line 162

def add_answer(rr) #:nodoc: all
  if (!@answer.include?rr)
    @answer << rr
    @header.ancount = @answer.length
  end
end

#add_authority(rr) ⇒ Object Also known as: add_update

:nodoc: all



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# File 'lib/Dnsruby/message.rb', line 175

def add_authority(rr) #:nodoc: all
  if (!@authority.include?rr)
    @authority << rr
    @header.nscount = @authority.length
  end
end

#add_question(question, type = Types.A, klass = Classes.IN) ⇒ Object Also known as: add_zone

Add a new Question to the Message. Takes either a Question, or a name, and an optional type and class.

  • msg.add_question(Question.new(“example.com”, ‘MX’))

  • msg.add_question(“example.com”) # defaults to Types.A, Classes.IN

  • msg.add_question(“example.com”, Types.LOC)



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# File 'lib/Dnsruby/message.rb', line 147

def add_question(question, type=Types.A, klass=Classes.IN)
  if (!question.kind_of?Question) 
    question = Question.new(question, type, klass)
  end
  @question << question
  @header.qdcount = @question.length
end

#each_additional ⇒ Object 



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# File 'lib/Dnsruby/message.rb', line 195

def each_additional
  @additional.each {|rec|
    yield rec
  }
end

#each_answer ⇒ Object Also known as: each_pre 



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# File 'lib/Dnsruby/message.rb', line 169

def each_answer
  @answer.each {|rec|
    yield rec
  }
end

#each_authority ⇒ Object Also known as: each_update 



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# File 'lib/Dnsruby/message.rb', line 182

def each_authority
  @authority.each {|rec|
    yield rec
  }
end

#each_question ⇒ Object Also known as: each_zone 



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# File 'lib/Dnsruby/message.rb', line 155

def each_question
  @question.each {|rec|
    yield rec
  }
end

#each_resource ⇒ Object

Calls each_answer, each_authority, each_additional



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# File 'lib/Dnsruby/message.rb', line 202

def each_resource
  each_answer {|rec| yield rec}
  each_authority {|rec| yield rec}
  each_additional {|rec| yield rec}
end

#encode ⇒ Object

Return the encoded form of the message If there is a TSIG record present and the record has not been signed then sign it



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# File 'lib/Dnsruby/message.rb', line 307

def encode
  if ((@tsigkey) && @tsigstate == :Unsigned && !@signing)
    @signing = true
    sign!
    @signing = false
  end
  return MessageEncoder.new {|msg|
    header = @header
    header.encode(msg)
    @question.each {|q|
      msg.put_name(q.qname)
      msg.put_pack('nn', q.qtype.code, q.qclass.code)
    }
    [@answer, @authority, @additional].each {|rr|
      rr.each {|r|
        name = r.name
        ttl = r.ttl
        if (r.type == Types.TSIG)
          msg.put_name(name, true)
        else
          msg.put_name(name)
        end
        msg.put_pack('nnN', r.type.code, r.klass.code, ttl)
        msg.put_length16 {r.encode_rdata(msg)}
      }
    }
  }.to_s
end

#set_tsig(*args) ⇒ Object

Sets the TSIG to sign this message with. Can either be a Dnsruby::RR::TSIG object, or it can be a (name, key) tuple, or it can be a hash which takes Dnsruby::RR::TSIG attributes (e.g. name, key, fudge, etc.)



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# File 'lib/Dnsruby/message.rb', line 221

def set_tsig(*args)
  if (args.length == 1)
    if (args[0].instance_of?RR::TSIG)
      @tsigkey = args[0]
    elsif (args[0].instance_of?Hash)
      @tsigkey = RR.create({:type=>'TSIG', :klass=>'ANY'}.merge(args[0]))
    else
      raise ArgumentError.new("Wrong type of argument to Dnsruby::Message#set_tsig - should be TSIG or Hash")
    end
  elsif (args.length == 2)
    @tsigkey = RR.create({:type=>'TSIG', :klass=>'ANY', :name=>args[0], :key=>args[1]})
  else
    raise ArgumentError.new("Wrong number of arguments to Dnsruby::Message#set_tsig")
  end
end

#sign!(*args) ⇒ Object

Signs the message. If used with no arguments, then the message must have already been set (set_tsig). Otherwise, the arguments can either be a Dnsruby::RR::TSIG object, or a (name, key) tuple, or a hash which takes Dnsruby::RR::TSIG attributes (e.g. name, key, fudge, etc.)



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# File 'lib/Dnsruby/message.rb', line 293

def sign!(*args)
  if (args.length > 0)
    set_tsig(*args)
    sign!
  else
    if ((@tsigkey) && @tsigstate == :Unsigned)
      @tsigkey.apply(self)
    end      
  end
end

#signed? ⇒ Boolean

Was this message signed by a TSIG?

Returns:

  • (Boolean) 


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# File 'lib/Dnsruby/message.rb', line 238

def signed?
  return (@tsigstate == :Signed ||
      @tsigstate == :Verified ||
      @tsigstate == :Failed)
end

#to_s ⇒ Object 



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# File 'lib/Dnsruby/message.rb', line 249

def to_s
  retval = "";
  
  if (@answerfrom != nil && @answerfrom != "")
    retval = retval + ";; Answer received from #{@answerfrom} (#{@answersize} bytes)\n;;\n";
  end
  
  retval = retval + ";; HEADER SECTION\n";
  retval = retval + @header.to_s;
  
  retval = retval + "\n";
  section = (@header.opcode == OpCode.UPDATE) ? "ZONE" : "QUESTION";
  retval = retval +  ";; #{section} SECTION (#{@header.qdcount}  record#{@header.qdcount == 1 ? '' : 's'})\n";
  each_question { |qr|
    retval = retval + ";; #{qr.to_s}\n";
  }
  
  retval = retval + "\n";
  section = (@header.opcode == OpCode.UPDATE) ? "PREREQUISITE" : "ANSWER";
  retval = retval + ";; #{section} SECTION (#{@header.ancount}  record#{@header.ancount == 1 ? '' : 's'})\n";
  each_answer { |rr|
    retval = retval + rr.to_s + "\n";
  }
  
  retval = retval + "\n";
  section = (@header.opcode == OpCode.UPDATE) ? "UPDATE" : "AUTHORITY";
  retval = retval + ";; #{section} SECTION (#{@header.nscount}  record#{@header.nscount == 1 ? '' : 's'})\n";
  each_authority { |rr|
    retval = retval + rr.to_s + "\n";
  }
  
  retval = retval + "\n";
  retval = retval + ";; ADDITIONAL SECTION (#{@header.arcount}  record#{@header.arcount == 1 ? '' : 's'})\n";
  each_additional { |rr|
    retval = retval + rr.to_s+ "\n";
  }
  
  return retval;
end

#tsig ⇒ Object

Returns the TSIG record from the ADDITIONAL section, if one is present.



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# File 'lib/Dnsruby/message.rb', line 209

def tsig
  if (@additional.last)
    if (@additional.last.rr_type == Types.TSIG)
      return @additional.last
    end
  end
  return nil
end

#verified? ⇒ Boolean

If this message was signed by a TSIG, was the TSIG verified?

Returns:

  • (Boolean) 


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# File 'lib/Dnsruby/message.rb', line 245

def verified?
  return (@tsigstate == :Verified)
end