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DN Class to escape and parse DNs.

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Jamstah 2011-01-11 16:27:45 +00:00
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lib/net/ldap/dn.rb Normal file
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# LDAP DN support classes
#
##
# Objects of this class represent an LDAP DN.
#
# In LDAP-land, a DN ("Distinguished Name") is a unique identifier for an
# entry within an LDAP directory. It is made up of a number of other
# attributes strung together, to identify the entry in the tree.
#
# Each attribute that makes up a DN needs to have its value escaped so that
# the DN is valid. This class helps take care of that.
#
# A fully escaped DN needs to be unescaped when analysing its contents. This
# class also helps take care of that.
class Net::LDAP::DN
##
# Initialize a DN, escaping as required. Pass in attributes in name/value
# pairs. If there is a left over argument, it will be appended to the dn
# without escaping (useful for a base string).
#
# Most uses of this class will be to escape a DN, rather than to parse it,
# so storing the dn as an escaped String and parsing parts as required with
# a state machine seems sensible.
def initialize(*args)
buffer = StringIO.new
args.each_index do |index|
buffer << "=" if index % 2 == 1
buffer << "," if index % 2 == 0 && index != 0
if index < args.length - 1 || index % 2 == 1
buffer << Net::LDAP::DN.escape(args[index])
else
buffer << args[index]
end
end
@dn = buffer.string
end
##
# Parse a DN into key value pairs using ASN from
# http://tools.ietf.org/html/rfc2253 section 3.
#
def each_pair
state = :key
key = StringIO.new
value = StringIO.new
hex_buffer = ""
@dn.each_char do |char|
case state
when :key then case char
when 'a'..'z','A'..'Z' then
state = :key_normal
key << char
when '0'..'9' then
state = :key_oid
key << char
when ' ' then state = :key
else raise "DN badly formed"
end
when :key_normal then case char
when '=' then state = :value
when 'a'..'z','A'..'Z','0'..'9','-',' ' then key << char
else raise "DN badly formed"
end
when :key_oid then case char
when '=' then state = :value
when '0'..'9','.',' ' then key << char
else raise "DN badly formed"
end
when :value then case char
when '\\' then state = :value_normal_escape
when '"' then state = :value_quoted
when ' ' then state = :value
when '#' then
state = :value_hexstring
value << char
when ',' then
state = :key
yield key.string.strip, value.string.rstrip
key = StringIO.new
value = StringIO.new;
else
state = :value_normal
value << char
end
when :value_normal then case char
when '\\' then state = :value_normal_escape
when ',' then
state = :key
yield key.string.strip, value.string.rstrip
key = StringIO.new
value = StringIO.new;
else value << char
end
when :value_normal_escape then case char
when '0'..'9', 'a'..'f', 'A'..'F' then
state = :value_normal_escape_hex
hex_buffer = char
else state = :value_normal; value << char
end
when :value_normal_escape_hex then case char
when '0'..'9', 'a'..'f', 'A'..'F' then
state = :value_normal
value << "#{hex_buffer}#{char}".to_i(16).chr
else raise "DN badly formed"
end
when :value_quoted then case char
when '\\' then state = :value_quoted_escape
when '"' then state = :value_end
else value << char
end
when :value_quoted_escape then case char
when '0'..'9', 'a'..'f', 'A'..'F' then
state = :value_quoted_escape_hex
hex_buffer = char
else state = :value_quoted; value << char
end
when :value_quoted_escape_hex then case char
when '0'..'9', 'a'..'f', 'A'..'F' then
state = :value_quoted
value << "#{hex_buffer}#{char}".to_i(16).chr
else raise "DN badly formed"
end
when :value_hexstring then case char
when '0'..'9', 'a'..'f', 'A'..'F' then
state = :value_hexstring_hex
value << char
when ' ' then state = :value_end
when ',' then
state = :key
yield key.string.strip, value.string.rstrip
key = StringIO.new
value = StringIO.new;
else raise "DN badly formed"
end
when :value_hexstring_hex then case char
when '0'..'9', 'a'..'f', 'A'..'F' then
state = :value_hexstring
value << char
else raise "DN badly formed"
end
when :value_end then case char
when ' ' then state = :value_end
when ',' then
state = :key
yield key.string.strip, value.string.rstrip
key = StringIO.new
value = StringIO.new;
else raise "DN badly formed"
end
else raise "Fell out of state machine"
end
end
# Last pair
if [:value, :value_normal, :value_hexstring, :value_end].include? state
yield key.string.strip, value.string.rstrip
else
raise "DN badly formed"
end
end
##
# Returns the DN as an array in the form expected by the constructor.
def to_a
a = []
self.each_pair { |key, value| a << key << value }
a
end
##
# Return the DN as an escaped string.
def to_s
@dn
end
# http://tools.ietf.org/html/rfc2253 section 2.4 lists these exceptions
# for dn values. All of the following must be escaped in any normal
# string using a single backslash ('\') as escape.
#
ESCAPES = {
',' => ',',
'+' => '+',
'"' => '"',
'\\' => '\\',
'<' => '<',
'>' => '>',
';' => ';',
}
# Compiled character class regexp using the keys from the above hash, and
# checking for a space or # at the start, or space at the end, of the
# string.
ESCAPE_RE = Regexp.new(
"(^ |^#| $|[" +
ESCAPES.keys.map { |e| Regexp.escape(e) }.join +
"])")
##
# Escape a string for use in a DN value
def self.escape(string)
string.gsub(ESCAPE_RE) { |char| "\\" + ESCAPES[char] }
end
##
# Proxy all other requests to the string object, because a DN is mainly
# used within the library as a string
def method_missing(method, *args, &block)
@dn.send(method, *args, &block)
end
end