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)

Additional information

security_level records the current DNSSEC status of this Message. answerfrom records the server which this Message was received from. cached records whether this response came from the cache.

Direct Known Subclasses

Update

Defined Under Namespace

Classes: Section, SecurityLevel

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 189

def initialize(*args)
  @header = Header.new()
  #      @question = Section.new(self)
  @question = []
  @answer = Section.new(self)
  @authority = Section.new(self)
  @additional = Section.new(self)
  @tsigstate = :Unsigned
  @signing = false
  @tsigkey = nil
  @answerfrom = nil
  @answerip = nil
  @send_raw = false
  @do_validation = true
  @do_caching = true
  @security_level = SecurityLevel.UNCHECKED
  @security_error = nil
  @cached = false
  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 229

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 225

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 234

def answerfrom
  @answerfrom
end

#answerip ⇒ Object

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



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# File 'lib/Dnsruby/message.rb', line 237

def answerip
  @answerip
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 240

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 227

def authority
  @authority
end

#cached ⇒ Object

If the Message was returned from the cache, the cached flag will be set true. It will be false otherwise.



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# File 'lib/Dnsruby/message.rb', line 87

def cached
  @cached
end

#do_caching ⇒ Object

do_caching is set by default. If you do not wish dnsruby to inspect the cache before sending the query, nor cache the result of the query, then set do_caching to false.



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# File 'lib/Dnsruby/message.rb', line 275

def do_caching
  @do_caching
end

#do_validation ⇒ Object

do_validation is set by default. If you do not wish dnsruby to validate this message (on a Resolver with @dnssec==true), then set do_validation to false. This option does not affect caching, or the header options



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# File 'lib/Dnsruby/message.rb', line 270

def do_validation
  @do_validation
end

#header ⇒ Object

The header section, a Dnsruby::Header object.



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# File 'lib/Dnsruby/message.rb', line 231

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 222

def question
  @question
end

#security_error ⇒ Object

If there was a problem verifying this message with DNSSEC, then securiy_error will hold a description of the problem. It defaults to “”



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# File 'lib/Dnsruby/message.rb', line 83

def security_error
  @security_error
end

#security_level ⇒ Object

If dnssec is set on, then each message will have the security level set To find the precise error (if any), call Dnsruby::Dnssec::validate(msg) - the resultant exception will define the error.



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# File 'lib/Dnsruby/message.rb', line 80

def security_level
  @security_level
end

#send_raw ⇒ Object

Set send_raw if you wish to send and receive the response to this Message with no additional processing. In other words, if set, then Dnsruby will not touch the Header of the outgoing Message. This option does not affect caching or dnssec validation

This option should not normally be set.



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# File 'lib/Dnsruby/message.rb', line 265

def send_raw
  @send_raw
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 244

def tsigerror
  @tsigerror
end

#tsigstart ⇒ Object

–



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# File 'lib/Dnsruby/message.rb', line 256

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 by TSIG

  • :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 253

def tsigstate
  @tsigstate
end

Class Method Details

.decode(m) ⇒ Object

Decode the encoded message



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# File 'lib/Dnsruby/message.rb', line 592

def Message.decode(m)
  o = Message.new()
  begin
    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)
            Dnsruby.log.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
      }
    }
  rescue DecodeError => e
    # So we got a decode error
    # However, we might have been able to fill in many parts of the message
    # So let's raise the DecodeError, but add the partially completed message
    e.partial_message = o
    raise e
  end
  return o
end

Instance Method Details

#==(other) ⇒ Object 



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# File 'lib/Dnsruby/message.rb', line 305

def ==(other)
  ret = false
  if (other.kind_of?Message)
    ret = @header == other.header &&
      @question[0] == other.question[0] &&
      @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 404

def add_additional(rr) #:nodoc: all
  if (!@additional.include?rr)
    @additional << rr
    update_counts
  end
end

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

:nodoc: all



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# File 'lib/Dnsruby/message.rb', line 378

def add_answer(rr) #:nodoc: all
  if (!@answer.include?rr)
    @answer << rr
    update_counts
  end
end

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

:nodoc: all



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# File 'lib/Dnsruby/message.rb', line 391

def add_authority(rr) #:nodoc: all
  if (!@authority.include?rr)
    @authority << rr
    update_counts
  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 356

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

#each_additional ⇒ Object 



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# File 'lib/Dnsruby/message.rb', line 411

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 385

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 398

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 364

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 423

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

#each_section ⇒ Object

Yields each section (question, answer, authority, additional)



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# File 'lib/Dnsruby/message.rb', line 418

def each_section
  [@answer, @authority, @additional].each {|section| yield section}
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 570

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|
        msg.put_rr(r)
      }
    }
  }.to_s
end

#get_exception ⇒ Object 



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# File 'lib/Dnsruby/message.rb', line 277

def get_exception
  exception = nil
  if (rcode==RCode.NXDOMAIN)
    exception = NXDomain.new
  elsif (rcode==RCode.SERVFAIL)
    exception = ServFail.new
  elsif (rcode==RCode.FORMERR)
    exception = FormErr.new
  elsif (rcode==RCode.NOTIMP)
    exception = NotImp.new
  elsif (rcode==RCode.REFUSED)
    exception = Refused.new
  elsif (rcode==RCode.NOTZONE)
    exception = NotZone.new
  elsif (rcode==RCode.NOTAUTH)
    exception = NotAuth.new
  elsif (rcode==RCode.NXRRSET)
    exception = NXRRSet.new
  elsif (rcode==RCode.YXRRSET)
    exception = YXRRSet.new
  elsif (rcode==RCode.YXDOMAIN)
    exception = YXDomain.new
  elsif (rcode >= RCode.BADSIG && rcode <= RCode.BADALG)
    return VerifyError.new # @TODO@
  end
  return exception
end

#get_opt ⇒ Object 



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# File 'lib/Dnsruby/message.rb', line 470

def get_opt
  each_additional do |r|
    if (r.type == Types::OPT)
      return r
    end
  end
  return nil
end

#rcode ⇒ Object 



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# File 'lib/Dnsruby/message.rb', line 479

def rcode
  rcode = @header.get_header_rcode
  opt = get_opt
  if (opt != nil)
    rcode = rcode.code + (opt.xrcode.code << 4)
    rcode = RCode.new(rcode)
  end
  return rcode;
end

#rrset(name, type, klass = Classes::IN) ⇒ Object

Return the first rrset of the specified attributes in the message



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# File 'lib/Dnsruby/message.rb', line 318

def rrset(name, type, klass = Classes::IN)
  [@answer, @authority, @additional].each do |section|
    if ((rrset = section.rrset(name, type, klass)).length > 0)
      return rrset
    end
  end
  return RRSet.new
end

#rrsets(type, klass = Classes::IN) ⇒ Object

Return the rrsets of the specified type in the message



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# File 'lib/Dnsruby/message.rb', line 328

def rrsets(type, klass=Classes::IN)
  rrsetss = []
  [@answer, @authority, @additional].each do |section|
    if ((rrsets = section.rrsets(type, klass)).length > 0)
      rrsets.each {|rrset|
        rrsetss.push(rrset)
      }
    end
  end
  return rrsetss
end

#section_rrsets(type = nil, include_opt = false) ⇒ Object

Return a hash, with the section as key, and the RRSets in that section as the data : => section_rrs



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# File 'lib/Dnsruby/message.rb', line 342

def section_rrsets(type = nil, include_opt = false)
  ret = {}
  ["answer", "authority", "additional"].each do |section|
    ret[section] = self.send(section).rrsets(type, include_opt)
  end
  return ret
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 442

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.)

NOTE that this method should only be called by the resolver, rather than the client code. To use signing from the client, call Dnsruby::Resolver#tsig=



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# File 'lib/Dnsruby/message.rb', line 556

def sign!(*args) #:nodoc: all
  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 459

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

#to_s ⇒ Object 



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# File 'lib/Dnsruby/message.rb', line 489

def to_s
  retval = "";
  
  if (@answerfrom != nil && @answerfrom != "")
    retval = retval + ";; Answer received from #{@answerfrom} (#{@answersize} bytes)\n;;\n";
  end
  retval = retval + ";; Security Level : #{@security_level.string}\n"
  
  retval = retval + ";; HEADER SECTION\n"
  # OPT pseudosection? EDNS flags, udpsize
  opt = get_opt
  if (!opt)
    retval = retval + @header.to_s
  else
    retval = retval + @header.to_s_with_rcode(rcode())
  end
  retval = retval + "\n"
  
  if (opt)
    retval = retval + opt.to_s
    retval = retval + "\n"
  end
        
  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";
  }
  
  if (@answer.size > 0)
    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";
    }
  end
  
  if (@authority.size > 0)
    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";
    }
  end
  
  if ((@additional.size > 0 && !opt) || (@additional.size > 1))
    retval = retval + "\n";
    retval = retval + ";; ADDITIONAL SECTION (#{@header.arcount}  record#{@header.arcount == 1 ? '' : 's'})\n";
    each_additional { |rr|
      if (rr.type != Types::OPT)
        retval = retval + rr.to_s+ "\n"
      end
    }
  end
  
  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 430

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

#update_counts ⇒ Object

:nodoc:all



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# File 'lib/Dnsruby/message.rb', line 370

def update_counts # :nodoc:all
  @header.ancount = @answer.length
  @header.arcount = @additional.length
  @header.qdcount = @question.length
  @header.nscount = @authority.length
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 466

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