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”)



186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
 
# File 'lib/Dnsruby/message.rb', line 186

def initialize(*args)
  @header = Header.new()
  @question = Section.new(self)
  @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.



225
226
227
 
# File 'lib/Dnsruby/message.rb', line 225

def additional
  @additional
end

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

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



221
222
223
 
# File 'lib/Dnsruby/message.rb', line 221

def answer
  @answer
end

#answerfrom ⇒ Object

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



230
231
232
 
# File 'lib/Dnsruby/message.rb', line 230

def answerfrom
  @answerfrom
end

#answerip ⇒ Object

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



233
234
235
 
# File 'lib/Dnsruby/message.rb', line 233

def answerip
  @answerip
end

#answersize ⇒ Object

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



236
237
238
 
# File 'lib/Dnsruby/message.rb', line 236

def answersize
  @answersize
end

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

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



223
224
225
 
# File 'lib/Dnsruby/message.rb', line 223

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.



87
88
89
 
# 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.



271
272
273
 
# File 'lib/Dnsruby/message.rb', line 271

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



266
267
268
 
# File 'lib/Dnsruby/message.rb', line 266

def do_validation
  @do_validation
end

#header ⇒ Object

The header section, a Dnsruby::Header object.



227
228
229
 
# File 'lib/Dnsruby/message.rb', line 227

def header
  @header
end

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

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



218
219
220
 
# File 'lib/Dnsruby/message.rb', line 218

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 “”



83
84
85
 
# 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.



80
81
82
 
# 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.



261
262
263
 
# File 'lib/Dnsruby/message.rb', line 261

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



240
241
242
 
# File 'lib/Dnsruby/message.rb', line 240

def tsigerror
  @tsigerror
end

#tsigstart ⇒ Object

–



252
253
254
 
# File 'lib/Dnsruby/message.rb', line 252

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



249
250
251
 
# File 'lib/Dnsruby/message.rb', line 249

def tsigstate
  @tsigstate
end

Class Method Details

.decode(m) ⇒ Object

Decode the encoded message



576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
 
# File 'lib/Dnsruby/message.rb', line 576

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)
          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
    }
  }
  return o
end

Instance Method Details

#==(other) ⇒ Object 



291
292
293
294
295
296
297
298
299
300
301
 
# File 'lib/Dnsruby/message.rb', line 291

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



388
389
390
391
392
393
 
# File 'lib/Dnsruby/message.rb', line 388

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



362
363
364
365
366
367
 
# File 'lib/Dnsruby/message.rb', line 362

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



375
376
377
378
379
380
 
# File 'lib/Dnsruby/message.rb', line 375

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)



340
341
342
343
344
345
346
 
# File 'lib/Dnsruby/message.rb', line 340

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 



395
396
397
398
399
 
# File 'lib/Dnsruby/message.rb', line 395

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

#each_answer ⇒ Object Also known as: each_pre 



369
370
371
372
373
 
# File 'lib/Dnsruby/message.rb', line 369

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

#each_authority ⇒ Object Also known as: each_update 



382
383
384
385
386
 
# File 'lib/Dnsruby/message.rb', line 382

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

#each_question ⇒ Object Also known as: each_zone 



348
349
350
351
352
 
# File 'lib/Dnsruby/message.rb', line 348

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

#each_resource ⇒ Object

Calls each_answer, each_authority, each_additional



407
408
409
410
411
 
# File 'lib/Dnsruby/message.rb', line 407

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)



402
403
404
 
# File 'lib/Dnsruby/message.rb', line 402

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



554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
 
# File 'lib/Dnsruby/message.rb', line 554

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 



273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
 
# File 'lib/Dnsruby/message.rb', line 273

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.BADSIG && rcode <= RCode.BADALG)
    return VerifyError.new # @TODO@
  end
  return exception
end

#get_opt ⇒ Object 



454
455
456
457
458
459
460
461
 
# File 'lib/Dnsruby/message.rb', line 454

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

#rcode ⇒ Object 



463
464
465
466
467
468
469
470
471
 
# File 'lib/Dnsruby/message.rb', line 463

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



304
305
306
307
308
309
310
311
 
# File 'lib/Dnsruby/message.rb', line 304

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



314
315
316
317
318
319
320
321
322
 
# File 'lib/Dnsruby/message.rb', line 314

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



326
327
328
329
330
331
332
 
# File 'lib/Dnsruby/message.rb', line 326

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.)



426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
 
# File 'lib/Dnsruby/message.rb', line 426

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=



540
541
542
543
544
545
546
547
548
549
 
# File 'lib/Dnsruby/message.rb', line 540

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) 


443
444
445
446
447
 
# File 'lib/Dnsruby/message.rb', line 443

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

#to_s ⇒ Object 



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
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
 
# File 'lib/Dnsruby/message.rb', line 473

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.



414
415
416
417
418
419
420
421
 
# File 'lib/Dnsruby/message.rb', line 414

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



354
355
356
357
358
359
 
# File 'lib/Dnsruby/message.rb', line 354

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) 


450
451
452
 
# File 'lib/Dnsruby/message.rb', line 450

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