Class: Dnsruby::Name

Inherits:
Object
  • Object
show all
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



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# File 'lib/Dnsruby/name.rb', line 72

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 (readonly)

Returns the value of attribute labels.



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# File 'lib/Dnsruby/name.rb', line 68

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



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# File 'lib/Dnsruby/name.rb', line 42

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.kind_of?String)?arg.last : arg.last.string) ? true : false)
  else        
    raise ArgumentError.new("cannot interpret as DNS name: #{arg.inspect}")
  end
end

.decode(wire) ⇒ Object

:nodoc: all



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# File 'lib/Dnsruby/name.rb', line 229

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;
  
  while (i < length )
    c=wire.unpack("x#{i}C1") [0]
    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 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.



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# File 'lib/Dnsruby/name.rb', line 273

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

.encodedlabels2name(labels) ⇒ Object

:nodoc: all



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# File 'lib/Dnsruby/name.rb', line 221

def self.encodedlabels2name(labels) #:nodoc: all
  ls = []
  labels.each do |l|
    ls.push(Name.decode(l.string))
  end
  return Name.new(ls)
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.



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# File 'lib/Dnsruby/name.rb', line 210

def self.name2encodedlabels (dName) #:nodoc: all
  names=[]
  j=0;
  while (dName && dName.length > 0)
    names[j],dName = encode(dName)
    j+=1
  end
  
  return names
end

.split_escaped(arg) ⇒ Object

:nodoc: all



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# File 'lib/Dnsruby/name.rb', line 63

def self.split_escaped(arg) #:nodoc: all
  encodedlabels = name2encodedlabels(arg)
  return encodedlabels2name(encodedlabels).labels
end

Instance Method Details

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

:nodoc:



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# File 'lib/Dnsruby/name.rb', line 149

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

#[](i) ⇒ Object

:nodoc: all



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# File 'lib/Dnsruby/name.rb', line 185

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

#absolute=(on) ⇒ Object

:nodoc:



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# File 'lib/Dnsruby/name.rb', line 102

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

#absolute? ⇒ Boolean

Returns true if this Name is absolute

Returns:

  • (Boolean) 


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# File 'lib/Dnsruby/name.rb', line 98

def absolute?
  return @absolute
end

#canonically_before(n) ⇒ Object 



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# File 'lib/Dnsruby/name.rb', line 119

def canonically_before(n)
  if (!(Name === n))
    n = Name.create(n)
  end
  # @TODO@ 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 



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

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

#hash ⇒ Object

:nodoc:



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# File 'lib/Dnsruby/name.rb', line 173

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

#inspect ⇒ Object

:nodoc:



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# File 'lib/Dnsruby/name.rb', line 93

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

#length ⇒ Object

:nodoc: all



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# File 'lib/Dnsruby/name.rb', line 181

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

#strip_label ⇒ Object

:nodoc:



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# File 'lib/Dnsruby/name.rb', line 106

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) 


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# File 'lib/Dnsruby/name.rb', line 165

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



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# File 'lib/Dnsruby/name.rb', line 177

def to_a #:nodoc: all
  return @labels
end

#to_s ⇒ 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"



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# File 'lib/Dnsruby/name.rb', line 199

def to_s
  return @labels.collect{|l| (l.kind_of?String) ? l : l.string}.join('.')    
end

#wild? ⇒ Boolean

Is this name a wildcard?

Returns:

  • (Boolean) 


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# File 'lib/Dnsruby/name.rb', line 112

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