Class: Dnsruby::Message

Inherits:
Object
  • Object
show all
Defined in:
lib/dnsruby/message/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: 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/message.rb', line 105

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/message.rb', line 145

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/message.rb', line 141

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/message.rb', line 150

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/message.rb', line 153

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/message.rb', line 156

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/message.rb', line 143

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/message.rb', line 93

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/message.rb', line 191

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/message.rb', line 186

def do_validation
  @do_validation
end

#header ⇒ Object

The header section, a Dnsruby::Header object.



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

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/message.rb', line 138

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/message.rb', line 89

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/message.rb', line 85

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/message.rb', line 181

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/message.rb', line 160

def tsigerror
  @tsigerror
end

#tsigstart ⇒ Object

–



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# File 'lib/dnsruby/message/message.rb', line 172

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/message.rb', line 169

def tsigstate
  @tsigstate
end

Class Method Details

.decode(m) ⇒ Object

Decode the encoded message



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# File 'lib/dnsruby/message/message.rb', line 565

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
  o
end

Instance Method Details

#==(other) ⇒ Object 



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

def ==(other)
  other.kind_of?(Message) &&
      @header      == other.header &&
      @question[0] == other.question[0] &&
      @answer      == other.answer &&
      @authority   == other.authority &&
      @additional  == other.additional
end

#add_additional(rr) ⇒ Object

:nodoc: all



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# File 'lib/dnsruby/message/message.rb', line 333

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

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

Adds an RR to the answer section unless it already occurs.



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# File 'lib/dnsruby/message/message.rb', line 301

def add_answer(rr) #:nodoc: all
  _add_answer(rr)
end

#add_answer!(rr) ⇒ Object

When adding an RR to a Dnsruby::Message, add_answer checks to see if it already occurs, and, if so, does not add it again. This method adds the record whether or not it already occurs. This is needed in order to add a SOA record twice for an AXFR response.



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# File 'lib/dnsruby/message/message.rb', line 309

def add_answer!(rr)
  _add_answer(rr, true)
end

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

:nodoc: all



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# File 'lib/dnsruby/message/message.rb', line 320

def add_authority(rr) #:nodoc: all
  unless @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/message.rb', line 272

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

#clone ⇒ Object 



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# File 'lib/dnsruby/message/message.rb', line 605

def clone
  Message.decode(self.encode)
end

#each_additional ⇒ Object 



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# File 'lib/dnsruby/message/message.rb', line 340

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/message.rb', line 314

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/message.rb', line 327

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/message.rb', line 280

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/message.rb', line 350

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/message.rb', line 345

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/message.rb', line 542

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/message.rb', line 193

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
  exception
end

#get_opt ⇒ Object 



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# File 'lib/dnsruby/message/message.rb', line 397

def get_opt
  @additional.detect { |r| r.type == Types::OPT }
end

#old_to_s ⇒ Object 



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# File 'lib/dnsruby/message/message.rb', line 460

def old_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.old_to_s
  else
    retval = retval + @header.old_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

  retval
end

#rcode ⇒ Object 



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# File 'lib/dnsruby/message/message.rb', line 401

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

#remove_additional ⇒ Object 



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# File 'lib/dnsruby/message/message.rb', line 230

def remove_additional
  @additional = Section.new(self)
  @header.arcount = 0
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/message.rb', line 236

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
  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/message.rb', line 246

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
  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 => section_rrs}



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# File 'lib/dnsruby/message/message.rb', line 258

def section_rrsets(type = nil, include_opt = false)
  ret = {}
  %w(answer authority additional).each do |section|
    ret[section] = self.send(section).rrsets(type, include_opt)
  end
  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/message.rb', line 369

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/message.rb', line 528

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/message.rb', line 386

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

#to_s ⇒ Object 



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

def to_s
  s = ''  # the output string to return

  if @answerfrom && (! @answerfrom.empty?)
    s << ";; Answer received from #{@answerfrom} (#{@answersize} bytes)\n;;\n"
  end

  s << ";; Security Level : #{@security_level.string}\n"

  #  OPT pseudosection? EDNS flags, udpsize
  opt = get_opt

  if opt
    s << @header.to_s_with_rcode(rcode) << "\n#{opt}\n"
  else
    s << "#{@header}\n"
  end

  section = (@header.opcode == OpCode.UPDATE) ? 'ZONE' : 'QUESTION'
  s <<  ";; #{section} SECTION (#{@header.qdcount}  record#{@header.qdcount == 1 ? '' : 's'})\n"
  each_question { |qr| s << ";; #{qr}\n" }

  if @answer.size > 0
    s << "\n"
    section = (@header.opcode == OpCode.UPDATE) ? 'PREREQUISITE' : 'ANSWER'
    s << ";; #{section} SECTION (#{@header.ancount}  record#{@header.ancount == 1 ? '' : 's'})\n"
    each_answer { |rr| s << "#{rr}\n" }
  end

  if @authority.size > 0
    s << "\n"
    section = (@header.opcode == OpCode.UPDATE) ? 'UPDATE' : 'AUTHORITY'
    s << ";; #{section} SECTION (#{@header.nscount}  record#{@header.nscount == 1 ? '' : 's'})\n"
    each_authority { |rr| s << rr.to_s + "\n" }
  end

  if (@additional.size > 0 && !opt) || (@additional.size > 1)
    s << "\n;; ADDITIONAL SECTION (#{@header.arcount}  record#{@header.arcount == 1 ? '' : 's'})\n"
    each_additional { |rr|
      if rr.type != Types::OPT
        s << rr.to_s+ "\n"
      end
    }
  end

  s
end

#tsig ⇒ Object

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



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# File 'lib/dnsruby/message/message.rb', line 357

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

#update_counts ⇒ Object

:nodoc:all



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# File 'lib/dnsruby/message/message.rb', line 286

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/message.rb', line 393

def verified?
  @tsigstate == :Verified
end