Class: Dnsruby::Name

Inherits:
Object
  • Object
show all
Includes:
Comparable
Defined in:
lib/dnsruby/name.rb

Overview

Dnsruby::Name class

A representation of a DNS name (RFC1035, section 3.1)

methods

  • Name::create(namestring)

  • Name#absolute?

  • Name#wild?

  • Name#subdomain_of?(other)

  • Name#labels

Defined Under Namespace

Classes: Label

Constant Summary collapse

MaxNameLength = 
255

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(labels, absolute = true) ⇒ Name

This method should only be called internally. Use Name::create to create a new Name



79
80
81
82
83
84
85
86
87
88
89
90
91
92
 
# File 'lib/dnsruby/name.rb', line 79

def initialize(labels, absolute=true) #:nodoc: all
  total_length=labels.length-1
  labels.each do |l|
    if (!l.kind_of?Label)
      raise ArgumentError.new("Name::new called with non-labels. Use Name::create instead?")
    end
    total_length+=l.length
  end
  if (total_length > MaxNameLength)
    raise ResolvError.new("Name length is #{total_length}, greater than max of #{MaxNameLength} octets!")
  end
  @labels = labels
  @absolute = absolute
end

Instance Attribute Details

#labels ⇒ Object

Returns the value of attribute labels.



75
76
77
 
# File 'lib/dnsruby/name.rb', line 75

def labels
  @labels
end

Class Method Details

.create(arg) ⇒ Object

–

A Name is a collection of Labels. Each label is presentation-formatted
When a Name is wire-encoded, the label array is walked, and each label is wire-encoded.
When a Name is unencoded, each label is unencoded, and added to the Name collection of labels.
When a Name is made from a string, the Name is split into Labels.

++ Creates a new Dnsruby::Name from arg. arg can be :

  • Name

    returns arg

  • String

    returns a new Name



43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
 
# File 'lib/dnsruby/name.rb', line 43

def self.create(arg)
  case arg
  when Name
    return Name.new(arg.labels, arg.absolute?)
  when String
    #         arg.gsub!(/\.$/o, "")
    if (arg==".")
      return Name.new([],true)
    end
    if (arg=="")
      return Name.new([],false)
    end
    return Name.new(split_escaped(arg), /\.\z/ =~ arg ? true : false)
    #         return Name.new(Label.split(arg), /\.\z/ =~ arg ? true : false)
  when Array
    return Name.new(arg, /\.\z/ =~ (arg.last ? ((arg.last.kind_of?String)?arg.last : arg.last.string) : arg.last) ? true : false)
  else
    raise ArgumentError.new("cannot interpret as DNS name: #{arg.inspect}")
  end
end

.decode(wire) ⇒ Object

:nodoc: all



266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
 
# File 'lib/dnsruby/name.rb', line 266

def self.decode(wire) #:nodoc: all
  presentation=""
  length=wire.length
  #  There must be a nice regexp to do this.. but since I failed to
  #  find one I scan the name string until I find a '\', at that time
  #  I start looking forward and do the magic.

  i=0;

  unpacked = wire.unpack("C*")
  while (i < length )
    c = unpacked[i]
    if ( c < 33 || c > 126 )
      presentation=presentation + sprintf("\\%03u" ,c)
    elsif ( c.chr ==  "\"" )
      presentation=presentation +  "\\\""
    elsif ( c.chr ==  "\$")
      presentation=presentation +  "\\\$"
    elsif ( c.chr == "(" )
      presentation=presentation + "\\("
    elsif ( c.chr == ")" )
      presentation=presentation +  "\\)"
    elsif ( c.chr == ";" )
      presentation=presentation +  "\\;"
    elsif ( c.chr == "@" )
      presentation=presentation +  "\\@"
    elsif ( c.chr == "\\" )
      presentation=presentation + "\\\\"
    elsif ( c.chr == ".")
      presentation=presentation +  "\\."
    else
      presentation=presentation + c.chr()
    end
    i=i+1
  end

  return presentation
  #       return Label.new(presentation)
end

.encode(presentation) ⇒ Object

wire,leftover=presentation2wire(leftover)

Will parse the input presentation format and return everything before
the first non-escaped "." in the first element of the return array and
all that has not been parsed yet in the 2nd argument.



312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
 
# File 'lib/dnsruby/name.rb', line 312

def self.encode(presentation) #:nodoc: all
  presentation=presentation.to_s
  wire="";
  length=presentation.length;

  i=0;

  while (i < length )
    c=presentation.unpack("x#{i}C1") [0]
    if (c == 46) # ord('.')
      endstring = presentation[i+1, presentation.length-(i+1)]
      return Label.new(wire),endstring
    end
    if (c == 92) # ord'\\'
      # backslash found
      pos = i+1
      #  pos sets where next pattern matching should start
      if (presentation.index(/\G(\d\d\d)/o, pos))
        wire=wire+[$1.to_i].pack("C")
        i=i+3
      elsif(presentation.index(/\Gx([0..9a..fA..F][0..9a..fA..F])/o, pos))
        wire=wire+[$1].pack("H*")
        i=i+3
      elsif(presentation.index(/\G\./o, pos))
        wire=wire+"\."
        i=i+1
      elsif(presentation.index(/\G@/o,pos))
        wire=wire+"@"
        i=i+1
      elsif(presentation.index(/\G\(/o, pos))
        wire=wire+"("
        i=i+1
      elsif(presentation.index(/\G\)/o, pos))
        wire=wire+")"
        i=i+1
      elsif(presentation.index(/\G\\/o, pos))
        wire=wire+"\\"
        i+=1
      end
    else
      wire = wire + [c].pack("C")
    end
    i=i+1
  end

  return Label.new(wire)
end

.name2encodedlabels(dName) ⇒ Object

Utility function

name2labels to translate names from presentation format into an
array of "wire-format" labels.
in: dName a string with a domain name in presentation format (1035
sect 5.1)
out: an array of labels in wire format.



246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
 
# File 'lib/dnsruby/name.rb', line 246

def self.name2encodedlabels (dName) #:nodoc: all
  #  Check for "\" in the name  : If there, then decode properly - otherwise, cheat and split on "."
  if (dName.index("\\"))
    names=[]
    j=0;
    while (dName && dName.length > 0)
      names[j],dName = encode(dName)
      j+=1
    end

    return names
  else
    labels = []
    dName.split(".").each {|l|
      labels.push(Label.new(l))
    }
    return labels
  end
end

.split(name) ⇒ Object 



69
70
71
72
73
 
# File 'lib/dnsruby/name.rb', line 69

def self.split(name)
  encodedlabels = name2encodedlabels(name)
  labels = encodedlabels.each  {|el| Name.decode(el.to_s)}
  return labels
end

.split_escaped(arg) ⇒ Object

:nodoc: all



64
65
66
67
 
# File 'lib/dnsruby/name.rb', line 64

def self.split_escaped(arg) #:nodoc: all
  encodedlabels = name2encodedlabels(arg)
  return encodedlabels
end

Instance Method Details

#<=>(other) ⇒ Object 



135
136
137
138
139
140
141
142
 
# File 'lib/dnsruby/name.rb', line 135

def <=>(other)
  #  return -1 if other less than us, +1 if greater than us
  return 0 if (canonical == other.canonical)
  if (canonically_before(other))
    return +1
  end
  return -1
end

#==(other) ⇒ Object Also known as: eql?

:nodoc:



174
175
176
177
 
# File 'lib/dnsruby/name.rb', line 174

def ==(other) # :nodoc:
  return false if other.class != Name
  return @labels == other.labels && @absolute == other.absolute?
end

#[](i) ⇒ Object

:nodoc: all



210
211
212
 
# File 'lib/dnsruby/name.rb', line 210

def [](i) #:nodoc: all
  return @labels[i]
end

#absolute=(on) ⇒ Object

:nodoc:



109
110
111
 
# File 'lib/dnsruby/name.rb', line 109

def absolute=(on) # :nodoc:
  @absolute = on
end

#absolute? ⇒ Boolean

Returns true if this Name is absolute

Returns:

  • (Boolean) 


105
106
107
 
# File 'lib/dnsruby/name.rb', line 105

def absolute?
  return @absolute
end

#canonical ⇒ Object

Return the canonical form of this name (RFC 4034 section 6.2)



127
128
129
130
131
132
133
 
# File 'lib/dnsruby/name.rb', line 127

def canonical
  # 
  return MessageEncoder.new {|msg|
    msg.put_name(self, true)
  }.to_s

end

#canonically_before(n) ⇒ Object 



144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
 
# File 'lib/dnsruby/name.rb', line 144

def canonically_before(n)
  if (!(Name === n))
    n = Name.create(n)
  end
  #  Work out whether this name is canonically before the passed Name
  #  RFC 4034 section 6.1
  #  For the purposes of DNS security, owner names are ordered by treating
  # individual labels as unsigned left-justified octet strings.  The
  # absence of a octet sorts before a zero value octet, and uppercase
  # US-ASCII letters are treated as if they were lowercase US-ASCII
  # letters.
  # To compute the canonical ordering of a set of DNS names, start by
  # sorting the names according to their most significant (rightmost)
  # labels.  For names in which the most significant label is identical,
  # continue sorting according to their next most significant label, and
  # so forth.

  #  Get the list of labels for both names, and then swap them
  my_labels = @labels.reverse
  other_labels = n.labels.reverse
  my_labels.each_index {|i|
    if (!other_labels[i])
      return false
    end
    next if (other_labels[i].downcase == my_labels[i].downcase)
    return (my_labels[i].downcase < other_labels[i].downcase)
  }
  return true
end

#downcase ⇒ Object 



94
95
96
97
98
 
# File 'lib/dnsruby/name.rb', line 94

def downcase
  labels = []
  @labels.each do |label| labels << Label.new(label.downcase) end
  return Name.new(labels)
end

#hash ⇒ Object

:nodoc:



198
199
200
 
# File 'lib/dnsruby/name.rb', line 198

def hash # :nodoc:
  return @labels.hash ^ @absolute.hash
end

#inspect ⇒ Object

:nodoc:



100
101
102
 
# File 'lib/dnsruby/name.rb', line 100

def inspect # :nodoc:
  "#<#{self.class}: #{self.to_s}#{@absolute ? '.' : ''}>"
end

#length ⇒ Object

:nodoc: all



206
207
208
 
# File 'lib/dnsruby/name.rb', line 206

def length #:nodoc: all
  return @labels.length
end

#strip_label ⇒ Object

:nodoc:



113
114
115
116
 
# File 'lib/dnsruby/name.rb', line 113

def strip_label # :nodoc:
  n = Name.new(self.labels()[1, self.labels.length-1], self.absolute?)
  return n
end

#subdomain_of?(other) ⇒ Boolean

Tests subdomain-of relation : returns true if this name

is a subdomain of +other+.

  domain = Resolv::Name.create("y.z")
  p Resolv::Name.create("w.x.y.z").subdomain_of?(domain) #=> true
  p Resolv::Name.create("x.y.z").subdomain_of?(domain) #=> true
  p Resolv::Name.create("y.z").subdomain_of?(domain) #=> false
  p Resolv::Name.create("z").subdomain_of?(domain) #=> false
  p Resolv::Name.create("x.y.z.").subdomain_of?(domain) #=> false
  p Resolv::Name.create("w.z").subdomain_of?(domain) #=> false

Returns:

  • (Boolean)

Raises:

  • (ArgumentError) 


190
191
192
193
194
195
196
 
# File 'lib/dnsruby/name.rb', line 190

def subdomain_of?(other)
  raise ArgumentError, "not a domain name: #{other.inspect}" unless Name === other
  return false if @absolute != other.absolute?
  other_len = other.length
  return false if @labels.length <= other_len
  return @labels[-other_len, other_len] == other.to_a
end

#to_a ⇒ Object

:nodoc: all



202
203
204
 
# File 'lib/dnsruby/name.rb', line 202

def to_a #:nodoc: all
  return @labels
end

#to_s(include_absolute = false) ⇒ Object

returns the domain name as a string.

The domain name doesn't have a trailing dot even if the name object is
absolute.

Example :

  p Resolv::Name.create("x.y.z.").to_s #=> "x.y.z"
  p Resolv::Name.create("x.y.z").to_s #=> "x.y.z"



224
225
226
227
228
229
230
 
# File 'lib/dnsruby/name.rb', line 224

def to_s(include_absolute=false)
  ret = to_str(@labels)
  if (@absolute && include_absolute)
    ret += "."
  end
  return ret
end

#to_str(labels) ⇒ Object

:nodoc: all



232
233
234
235
236
237
 
# File 'lib/dnsruby/name.rb', line 232

def to_str(labels) # :nodoc: all
  ls =[]
  labels.each {|el| ls.push(Name.decode(el.to_s))}
  return ls.join('.')
  #       return @labels.collect{|l| (l.kind_of?String) ? l : l.string}.join('.')
end

#wild? ⇒ Boolean

Is this name a wildcard?

Returns:

  • (Boolean) 


119
120
121
122
123
124
 
# File 'lib/dnsruby/name.rb', line 119

def wild?
  if (labels.length == 0)
    return false
  end
  return (labels[0].string == '*')
end