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’)



105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
 
# 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.



145
146
147
 
# 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.



141
142
143
 
# 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



150
151
152
 
# 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



153
154
155
 
# 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



156
157
158
 
# 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.



143
144
145
 
# 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.



93
94
95
 
# 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.



191
192
193
 
# 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



186
187
188
 
# File 'lib/dnsruby/message/message.rb', line 186

def do_validation
  @do_validation
end

#header ⇒ Object

The header section, a Dnsruby::Header object.



147
148
149
 
# 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.



138
139
140
 
# 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 ''



89
90
91
 
# 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.



85
86
87
 
# 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.



181
182
183
 
# 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



160
161
162
 
# File 'lib/dnsruby/message/message.rb', line 160

def tsigerror
  @tsigerror
end

#tsigstart ⇒ Object

–



172
173
174
 
# 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



169
170
171
 
# File 'lib/dnsruby/message/message.rb', line 169

def tsigstate
  @tsigstate
end

Class Method Details

.decode(m) ⇒ Object

Decode the encoded message



552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
 
# File 'lib/dnsruby/message/message.rb', line 552

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 



221
222
223
224
225
226
227
228
 
# 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



320
321
322
323
324
325
 
# File 'lib/dnsruby/message/message.rb', line 320

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

:nodoc: all



294
295
296
297
298
299
 
# File 'lib/dnsruby/message/message.rb', line 294

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

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

:nodoc: all



307
308
309
310
311
312
 
# File 'lib/dnsruby/message/message.rb', line 307

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)



272
273
274
275
276
277
278
 
# 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 



592
593
594
 
# File 'lib/dnsruby/message/message.rb', line 592

def clone
  Message.decode(self.encode)
end

#each_additional ⇒ Object 



327
328
329
 
# File 'lib/dnsruby/message/message.rb', line 327

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

#each_answer ⇒ Object Also known as: each_pre 



301
302
303
304
305
 
# File 'lib/dnsruby/message/message.rb', line 301

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

#each_authority ⇒ Object Also known as: each_update 



314
315
316
317
318
 
# File 'lib/dnsruby/message/message.rb', line 314

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

#each_question ⇒ Object Also known as: each_zone 



280
281
282
283
284
 
# 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



337
338
339
340
341
 
# File 'lib/dnsruby/message/message.rb', line 337

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)



332
333
334
 
# File 'lib/dnsruby/message/message.rb', line 332

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



529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
 
# File 'lib/dnsruby/message/message.rb', line 529

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 



193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
 
# 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 



384
385
386
 
# File 'lib/dnsruby/message/message.rb', line 384

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

#old_to_s ⇒ Object 



447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
 
# File 'lib/dnsruby/message/message.rb', line 447

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 



388
389
390
391
392
393
394
395
396
 
# File 'lib/dnsruby/message/message.rb', line 388

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 



230
231
232
233
 
# 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



236
237
238
239
240
241
242
243
 
# 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



246
247
248
249
250
251
252
253
254
 
# 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}



258
259
260
261
262
263
264
 
# 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.)



356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
 
# File 'lib/dnsruby/message/message.rb', line 356

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=



515
516
517
518
519
520
521
522
523
524
 
# File 'lib/dnsruby/message/message.rb', line 515

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) 


373
374
375
376
377
 
# File 'lib/dnsruby/message/message.rb', line 373

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

#to_s ⇒ Object 



398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
 
# File 'lib/dnsruby/message/message.rb', line 398

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.



344
345
346
347
348
349
350
351
 
# File 'lib/dnsruby/message/message.rb', line 344

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

#update_counts ⇒ Object

:nodoc:all



286
287
288
289
290
291
 
# 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) 


380
381
382
 
# File 'lib/dnsruby/message/message.rb', line 380

def verified?
  @tsigstate == :Verified
end