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Jamstah
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DN Class to escape and parse DNs.
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‎lib/net/ldap/dn.rb

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# LDAP DN support classes
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#
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##
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# Objects of this class represent an LDAP DN.
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#
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# In LDAP-land, a DN ("Distinguished Name") is a unique identifier for an
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# entry within an LDAP directory. It is made up of a number of other
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# attributes strung together, to identify the entry in the tree.
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#
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# Each attribute that makes up a DN needs to have its value escaped so that
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# the DN is valid. This class helps take care of that.
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#
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# A fully escaped DN needs to be unescaped when analysing its contents. This
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# class also helps take care of that.
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class Net::LDAP::DN
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##
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# Initialize a DN, escaping as required. Pass in attributes in name/value
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# pairs. If there is a left over argument, it will be appended to the dn
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# without escaping (useful for a base string).
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#
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# Most uses of this class will be to escape a DN, rather than to parse it,
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# so storing the dn as an escaped String and parsing parts as required with
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# a state machine seems sensible.
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def initialize(*args)
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buffer = StringIO.new
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args.each_index do |index|
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buffer << "=" if index % 2 == 1
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buffer << "," if index % 2 == 0 && index != 0
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if index < args.length - 1 || index % 2 == 1
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buffer << Net::LDAP::DN.escape(args[index])
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else
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buffer << args[index]
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end
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end
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@dn = buffer.string
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end
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##
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# Parse a DN into key value pairs using ASN from
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# http://tools.ietf.org/html/rfc2253 section 3.
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#
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def each_pair
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state = :key
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key = StringIO.new
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value = StringIO.new
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hex_buffer = ""
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@dn.each_char do |char|
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case state
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when :key then case char
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when 'a'..'z','A'..'Z' then
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state = :key_normal
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key << char
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when '0'..'9' then
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state = :key_oid
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key << char
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when ' ' then state = :key
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else raise "DN badly formed"
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end
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when :key_normal then case char
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when '=' then state = :value
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when 'a'..'z','A'..'Z','0'..'9','-',' ' then key << char
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else raise "DN badly formed"
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end
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when :key_oid then case char
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when '=' then state = :value
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when '0'..'9','.',' ' then key << char
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else raise "DN badly formed"
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end
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when :value then case char
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when '\\' then state = :value_normal_escape
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when '"' then state = :value_quoted
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when ' ' then state = :value
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when '#' then
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state = :value_hexstring
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value << char
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when ',' then
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state = :key
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yield key.string.strip, value.string.rstrip
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key = StringIO.new
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value = StringIO.new;
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else
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state = :value_normal
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value << char
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end
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when :value_normal then case char
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when '\\' then state = :value_normal_escape
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when ',' then
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state = :key
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yield key.string.strip, value.string.rstrip
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key = StringIO.new
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value = StringIO.new;
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else value << char
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end
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when :value_normal_escape then case char
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when '0'..'9', 'a'..'f', 'A'..'F' then
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state = :value_normal_escape_hex
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hex_buffer = char
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else state = :value_normal; value << char
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end
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when :value_normal_escape_hex then case char
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when '0'..'9', 'a'..'f', 'A'..'F' then
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state = :value_normal
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value << "#{hex_buffer}#{char}".to_i(16).chr
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else raise "DN badly formed"
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end
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when :value_quoted then case char
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when '\\' then state = :value_quoted_escape
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when '"' then state = :value_end
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else value << char
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end
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when :value_quoted_escape then case char
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when '0'..'9', 'a'..'f', 'A'..'F' then
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state = :value_quoted_escape_hex
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hex_buffer = char
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else state = :value_quoted; value << char
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end
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when :value_quoted_escape_hex then case char
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when '0'..'9', 'a'..'f', 'A'..'F' then
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state = :value_quoted
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value << "#{hex_buffer}#{char}".to_i(16).chr
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else raise "DN badly formed"
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end
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when :value_hexstring then case char
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when '0'..'9', 'a'..'f', 'A'..'F' then
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state = :value_hexstring_hex
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value << char
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when ' ' then state = :value_end
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when ',' then
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state = :key
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yield key.string.strip, value.string.rstrip
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key = StringIO.new
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value = StringIO.new;
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else raise "DN badly formed"
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end
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when :value_hexstring_hex then case char
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when '0'..'9', 'a'..'f', 'A'..'F' then
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state = :value_hexstring
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value << char
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else raise "DN badly formed"
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end
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when :value_end then case char
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when ' ' then state = :value_end
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when ',' then
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state = :key
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yield key.string.strip, value.string.rstrip
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key = StringIO.new
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value = StringIO.new;
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else raise "DN badly formed"
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end
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else raise "Fell out of state machine"
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end
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end
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# Last pair
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if [:value, :value_normal, :value_hexstring, :value_end].include? state
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yield key.string.strip, value.string.rstrip
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else
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raise "DN badly formed"
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end
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end
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##
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# Returns the DN as an array in the form expected by the constructor.
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def to_a
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a = []
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self.each_pair { |key, value| a << key << value }
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a
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end
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##
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# Return the DN as an escaped string.
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def to_s
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@dn
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end
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# http://tools.ietf.org/html/rfc2253 section 2.4 lists these exceptions
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# for dn values. All of the following must be escaped in any normal
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# string using a single backslash ('\') as escape.
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#
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ESCAPES = {
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',' => ',',
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'+' => '+',
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'"' => '"',
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'\\' => '\\',
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'<' => '<',
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'>' => '>',
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';' => ';',
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}
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# Compiled character class regexp using the keys from the above hash, and
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# checking for a space or # at the start, or space at the end, of the
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# string.
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ESCAPE_RE = Regexp.new(
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"(^ |^#| $|[" +
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ESCAPES.keys.map { |e| Regexp.escape(e) }.join +
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"])")
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##
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# Escape a string for use in a DN value
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def self.escape(string)
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string.gsub(ESCAPE_RE) { |char| "\\" + ESCAPES[char] }
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end
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##
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# Proxy all other requests to the string object, because a DN is mainly
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# used within the library as a string
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def method_missing(method, *args, &block)
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@dn.send(method, *args, &block)
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end
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end

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