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Diffstat (limited to 'lib/gitlab/auth/ldap/dn.rb')
-rw-r--r-- | lib/gitlab/auth/ldap/dn.rb | 303 |
1 files changed, 303 insertions, 0 deletions
diff --git a/lib/gitlab/auth/ldap/dn.rb b/lib/gitlab/auth/ldap/dn.rb new file mode 100644 index 00000000000..1fa5338f5a6 --- /dev/null +++ b/lib/gitlab/auth/ldap/dn.rb @@ -0,0 +1,303 @@ +# -*- ruby encoding: utf-8 -*- + +# 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 |