debian-mirror-gitlab/lib/gitlab/auth/ldap/dn.rb
2020-04-08 14:13:33 +05:30

303 lines
11 KiB
Ruby

# frozen_string_literal: true
# Based on the `ruby-net-ldap` gem's `Net::LDAP::DN`
#
# For our purposes, this class is used to normalize DNs in order to allow proper
# comparison.
#
# E.g. DNs should be compared case-insensitively (in basically all LDAP
# implementations or setups), therefore we downcase every DN.
##
# Objects of this class represent an LDAP DN ("Distinguished Name"). 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.
module Gitlab
module Auth
module Ldap
class DN
FormatError = Class.new(StandardError)
MalformedError = Class.new(FormatError)
UnsupportedError = Class.new(FormatError)
def self.normalize_value(given_value)
dummy_dn = "placeholder=#{given_value}"
normalized_dn = new(*dummy_dn).to_normalized_s
normalized_dn.sub(/\Aplaceholder=/, '')
end
##
# 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)
if args.length > 1
initialize_array(args)
else
initialize_string(args[0])
end
end
##
# Parse a DN into key value pairs using ASN from
# http://tools.ietf.org/html/rfc2253 section 3.
# rubocop:disable Metrics/AbcSize
# rubocop:disable Metrics/CyclomaticComplexity
# rubocop:disable Metrics/PerceivedComplexity
def each_pair
state = :key
key = StringIO.new
value = StringIO.new
hex_buffer = ""
@dn.each_char.with_index do |char, dn_index|
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(MalformedError, "Unrecognized first character of an RDN attribute type name \"#{char}\"")
end
when :key_normal then
case char
when '=' then state = :value
when 'a'..'z', 'A'..'Z', '0'..'9', '-', ' ' then key << char
else raise(MalformedError, "Unrecognized RDN attribute type name character \"#{char}\"")
end
when :key_oid then
case char
when '=' then state = :value
when '0'..'9', '.', ' ' then key << char
else raise(MalformedError, "Unrecognized RDN OID attribute type name character \"#{char}\"")
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, rstrip_except_escaped(value.string, dn_index)
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, rstrip_except_escaped(value.string, dn_index)
key = StringIO.new
value = StringIO.new
when '+' then raise(UnsupportedError, "Multivalued RDNs are not supported")
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(MalformedError, "Invalid escaped hex code \"\\#{hex_buffer}#{char}\"")
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(MalformedError, "Expected the second character of a hex pair inside a double quoted value, but got \"#{char}\"")
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, rstrip_except_escaped(value.string, dn_index)
key = StringIO.new
value = StringIO.new
else raise(MalformedError, "Expected the first character of a hex pair, but got \"#{char}\"")
end
when :value_hexstring_hex then
case char
when '0'..'9', 'a'..'f', 'A'..'F' then
state = :value_hexstring
value << char
else raise(MalformedError, "Expected the second character of a hex pair, but got \"#{char}\"")
end
when :value_end then
case char
when ' ' then state = :value_end
when ',' then
state = :key
yield key.string.strip, rstrip_except_escaped(value.string, dn_index)
key = StringIO.new
value = StringIO.new
else raise(MalformedError, "Expected the end of an attribute value, but got \"#{char}\"")
end
else raise "Fell out of state machine"
end
end
# Last pair
raise(MalformedError, 'DN string ended unexpectedly') unless
[:value, :value_normal, :value_hexstring, :value_end].include? state
yield key.string.strip, rstrip_except_escaped(value.string, @dn.length)
end
def rstrip_except_escaped(str, dn_index)
str_ends_with_whitespace = str.match(/\s\z/)
if str_ends_with_whitespace
dn_part_ends_with_escaped_whitespace = @dn[0, dn_index].match(/\\(\s+)\z/)
if dn_part_ends_with_escaped_whitespace
dn_part_rwhitespace = dn_part_ends_with_escaped_whitespace[1]
num_chars_to_remove = dn_part_rwhitespace.length - 1
str = str[0, str.length - num_chars_to_remove]
else
str.rstrip!
end
end
str
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 } unless @dn.empty?
a
end
##
# Return the DN as an escaped string.
def to_s
@dn
end
##
# Return the DN as an escaped and normalized string.
def to_normalized_s
self.class.new(*to_a).to_s.downcase
end
# https://tools.ietf.org/html/rfc4514 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. The space character is left
# out here because in a "normalized" string, spaces should only be escaped
# if necessary (i.e. leading or trailing space).
NORMAL_ESCAPES = [',', '+', '"', '\\', '<', '>', ';', '='].freeze
# The following must be represented as escaped hex
HEX_ESCAPES = {
"\n" => '\0a',
"\r" => '\0d'
}.freeze
# 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("(^ |^#| $|[" +
NORMAL_ESCAPES.map { |e| Regexp.escape(e) }.join +
"])")
HEX_ESCAPE_RE = Regexp.new("([" +
HEX_ESCAPES.keys.map { |e| Regexp.escape(e) }.join +
"])")
##
# Escape a string for use in a DN value
def self.escape(string)
escaped = string.gsub(ESCAPE_RE) { |char| "\\" + char }
escaped.gsub(HEX_ESCAPE_RE) { |char| HEX_ESCAPES[char] }
end
private
def initialize_array(args)
buffer = StringIO.new
args.each_with_index do |arg, index|
if index.even? # key
buffer << "," if index > 0
buffer << arg
else # value
buffer << "="
buffer << self.class.escape(arg)
end
end
@dn = buffer.string
end
def initialize_string(arg)
@dn = arg.to_s
end
##
# Proxy all other requests to the string object, because a DN is mainly
# used within the library as a string
# rubocop:disable GitlabSecurity/PublicSend
def method_missing(method, *args, &block)
@dn.send(method, *args, &block)
end
##
# Redefined to be consistent with redefined `method_missing` behavior
def respond_to?(sym, include_private = false)
@dn.respond_to?(sym, include_private)
end
end
end
end
end