# HTTPClient - HTTP client library.
# Copyright (C) 2000-2015  NAKAMURA, Hiroshi  <nahi@ruby-lang.org>.
#
# This program is copyrighted free software by NAKAMURA, Hiroshi.  You can
# redistribute it and/or modify it under the same terms of Ruby's license;
# either the dual license version in 2003, or any later version.


require 'digest/md5'
require 'httpclient/session'
require 'mutex_m'


class HTTPClient

  NTLMEnabled = false
  SSPIEnabled = false
  GSSAPIEnabled = false

  # Common abstract class for authentication filter.
  #
  # There are 2 authentication filters.
  # WWWAuth:: Authentication filter for handling authentication negotiation
  #           between Web server.  Parses 'WWW-Authentication' header in
  #           response and generates 'Authorization' header in request.
  # ProxyAuth:: Authentication filter for handling authentication negotiation
  #             between Proxy server.  Parses 'Proxy-Authentication' header in
  #             response and generates 'Proxy-Authorization' header in request.
  class AuthFilterBase
  private

    def parse_authentication_header(res, tag)
      challenge = res.header[tag]
      return nil unless challenge
      challenge.collect { |c| parse_challenge_header(c) }.compact
    end

    def parse_challenge_header(challenge)
      scheme, param_str = challenge.scan(/\A(\S+)(?:\s+(.*))?\z/)[0]
      return nil if scheme.nil?
      return scheme, param_str
    end
  end


  # Authentication filter for handling authentication negotiation between
  # Web server.  Parses 'WWW-Authentication' header in response and
  # generates 'Authorization' header in request.
  #
  # Authentication filter is implemented using request filter of HTTPClient.
  # It traps HTTP response header and maintains authentication state, and
  # traps HTTP request header for inserting necessary authentication header.
  #
  # WWWAuth has sub filters (BasicAuth, DigestAuth, NegotiateAuth and
  # SSPINegotiateAuth) and delegates some operations to it.
  # NegotiateAuth requires 'ruby/ntlm' module (rubyntlm gem).
  # SSPINegotiateAuth requires 'win32/sspi' module (rubysspi gem).
  class WWWAuth < AuthFilterBase
    attr_reader :basic_auth
    attr_reader :digest_auth
    attr_reader :negotiate_auth
    attr_reader :sspi_negotiate_auth
    attr_reader :oauth

    # Creates new WWWAuth.
    def initialize
      @basic_auth = BasicAuth.new
      @digest_auth = DigestAuth.new
      @negotiate_auth = NegotiateAuth.new
      @ntlm_auth = NegotiateAuth.new('NTLM')
      @sspi_negotiate_auth = SSPINegotiateAuth.new
      @oauth = OAuth.new
      # sort authenticators by priority
      @authenticator = [@oauth, @negotiate_auth, @ntlm_auth, @sspi_negotiate_auth, @digest_auth, @basic_auth]
    end

    # Resets challenge state.  See sub filters for more details.
    def reset_challenge
      @authenticator.each do |auth|
        auth.reset_challenge
      end
    end

    # Set authentication credential.  See sub filters for more details.
    def set_auth(uri, user, passwd)
      @authenticator.each do |auth|
        auth.set(uri, user, passwd)
      end
      reset_challenge
    end

    # Filter API implementation.  Traps HTTP request and insert
    # 'Authorization' header if needed.
    def filter_request(req)
      @authenticator.each do |auth|
        next unless auth.set? # hasn't be set, don't use it
        if cred = auth.get(req)
          if cred == :skip
            # some authenticator (NTLM and Negotiate) does not
            # need to send extra header after authorization. In such case
            # it should block other authenticators to respond and :skip is
            # the marker for such case.
            return
          end
          req.header.set('Authorization', auth.scheme + " " + cred)
          return
        end
      end
    end

    # Filter API implementation.  Traps HTTP response and parses
    # 'WWW-Authenticate' header.
    #
    # This remembers the challenges for all authentication methods
    # available to the client. On the subsequent retry of the request,
    # filter_request will select the strongest method.
    def filter_response(req, res)
      command = nil
      if res.status == HTTP::Status::UNAUTHORIZED
        if challenge = parse_authentication_header(res, 'www-authenticate')
          uri = req.header.request_uri
          challenge.each do |scheme, param_str|
            @authenticator.each do |auth|
              next unless auth.set? # hasn't be set, don't use it
              if scheme.downcase == auth.scheme.downcase
                challengeable = auth.challenge(uri, param_str)
                command = :retry if challengeable
              end
            end
          end
          # ignore unknown authentication scheme
        end
      end
      command
    end
  end


  # Authentication filter for handling authentication negotiation between
  # Proxy server.  Parses 'Proxy-Authentication' header in response and
  # generates 'Proxy-Authorization' header in request.
  #
  # Authentication filter is implemented using request filter of HTTPClient.
  # It traps HTTP response header and maintains authentication state, and
  # traps HTTP request header for inserting necessary authentication header.
  #
  # ProxyAuth has sub filters (BasicAuth, NegotiateAuth, and SSPINegotiateAuth)
  # and delegates some operations to it.
  # NegotiateAuth requires 'ruby/ntlm' module.
  # SSPINegotiateAuth requires 'win32/sspi' module.
  class ProxyAuth < AuthFilterBase
    attr_reader :basic_auth
    attr_reader :digest_auth
    attr_reader :negotiate_auth
    attr_reader :sspi_negotiate_auth

    # Creates new ProxyAuth.
    def initialize
      @basic_auth = ProxyBasicAuth.new
      @negotiate_auth = NegotiateAuth.new
      @ntlm_auth = NegotiateAuth.new('NTLM')
      @sspi_negotiate_auth = SSPINegotiateAuth.new
      @digest_auth = ProxyDigestAuth.new
      # sort authenticators by priority
      @authenticator = [@negotiate_auth, @ntlm_auth, @sspi_negotiate_auth, @digest_auth, @basic_auth]
    end

    # Resets challenge state.  See sub filters for more details.
    def reset_challenge
      @authenticator.each do |auth|
        auth.reset_challenge
      end
    end

    # Set authentication credential.  See sub filters for more details.
    def set_auth(user, passwd)
      @authenticator.each do |auth|
        auth.set(nil, user, passwd)
      end
      reset_challenge
    end

    # Filter API implementation.  Traps HTTP request and insert
    # 'Proxy-Authorization' header if needed.
    def filter_request(req)
      @authenticator.each do |auth|
        next unless auth.set? # hasn't be set, don't use it
        if cred = auth.get(req)
          if cred == :skip
            # some authenticator (NTLM and Negotiate) does not
            # need to send extra header after authorization. In such case
            # it should block other authenticators to respond and :skip is
            # the marker for such case.
            return
          end
          req.header.set('Proxy-Authorization', auth.scheme + " " + cred)
          return
        end
      end
    end

    # Filter API implementation.  Traps HTTP response and parses
    # 'Proxy-Authenticate' header.
    def filter_response(req, res)
      command = nil
      if res.status == HTTP::Status::PROXY_AUTHENTICATE_REQUIRED
        if challenge = parse_authentication_header(res, 'proxy-authenticate')
          uri = req.header.request_uri
          challenge.each do |scheme, param_str|
            @authenticator.each do |auth|
              next unless auth.set? # hasn't be set, don't use it
              if scheme.downcase == auth.scheme.downcase
                challengeable = auth.challenge(uri, param_str)
                command = :retry if challengeable
              end
            end
          end
          # ignore unknown authentication scheme
        end
      end
      command
    end
  end

  # Authentication filter base class.
  class AuthBase
    include HTTPClient::Util

    # Authentication scheme.
    attr_reader :scheme

    def initialize(scheme)
      @scheme = scheme
      @challenge = {}
    end

    # Resets challenge state.  Do not send '*Authorization' header until the
    # server sends '*Authentication' again.
    def reset_challenge
      synchronize do
        @challenge.clear
      end
    end
  end

  # Authentication filter for handling BasicAuth negotiation.
  # Used in WWWAuth and ProxyAuth.
  class BasicAuth < AuthBase
    include Mutex_m

    # Send Authorization Header without receiving 401
    attr_accessor :force_auth

    # Creates new BasicAuth filter.
    def initialize
      super('Basic')
      @cred = nil
      @auth = {}
      @force_auth = false
    end

    # Set authentication credential.
    # uri == nil for generic purpose (allow to use user/password for any URL).
    def set(uri, user, passwd)
      synchronize do
        if uri.nil?
          @cred = ["#{user}:#{passwd}"].pack('m').tr("\n", '')
        else
          uri = Util.uri_dirname(uri)
          @auth[uri] = ["#{user}:#{passwd}"].pack('m').tr("\n", '')
        end
      end
    end

    # have we marked this as set - ie that it's valid to use in this context?
    def set?
      @cred || @auth.any?
    end

    # Response handler: returns credential.
    # It sends cred only when a given uri is;
    # * child page of challengeable(got *Authenticate before) uri and,
    # * child page of defined credential
    def get(req)
      target_uri = req.header.request_uri
      synchronize {
        return nil if !@force_auth and !@challenge.any? { |uri, ok|
          Util.uri_part_of(target_uri, uri) and ok
        }
        return @cred if @cred
        Util.hash_find_value(@auth) { |uri, cred|
          Util.uri_part_of(target_uri, uri)
        }
      }
    end

    # Challenge handler: remember URL for response.
    def challenge(uri, param_str = nil)
      synchronize {
        @challenge[urify(uri)] = true
        true
      }
    end
  end

  class ProxyBasicAuth < BasicAuth
    def set(uri, user, passwd)
      synchronize do
        @cred = ["#{user}:#{passwd}"].pack('m').tr("\n", '')
      end
    end

    def get(req)
      synchronize {
        return nil if !@force_auth and !@challenge['challenged']
        @cred
      }
    end

    # Challenge handler: remember URL for response.
    def challenge(uri, param_str = nil)
      synchronize {
        @challenge['challenged'] = true
        true
      }
    end
  end

  # Authentication filter for handling DigestAuth negotiation.
  # Used in WWWAuth.
  class DigestAuth < AuthBase
    include Mutex_m

    # Creates new DigestAuth filter.
    def initialize
      super('Digest')
      @auth = {}
      @nonce_count = 0
    end

    # Set authentication credential.
    # uri == nil is ignored.
    def set(uri, user, passwd)
      synchronize do
        if uri
          uri = Util.uri_dirname(uri)
          @auth[uri] = [user, passwd]
        end
      end
    end

    # have we marked this as set - ie that it's valid to use in this context?
    def set?
      @auth.any?
    end

    # Response handler: returns credential.
    # It sends cred only when a given uri is;
    # * child page of challengeable(got *Authenticate before) uri and,
    # * child page of defined credential
    def get(req)
      target_uri = req.header.request_uri
      synchronize {
        param = Util.hash_find_value(@challenge) { |uri, v|
          Util.uri_part_of(target_uri, uri)
        }
        return nil unless param
        user, passwd = Util.hash_find_value(@auth) { |uri, auth_data|
          Util.uri_part_of(target_uri, uri)
        }
        return nil unless user
        calc_cred(req, user, passwd, param)
      }
    end

    # Challenge handler: remember URL and challenge token for response.
    def challenge(uri, param_str)
      synchronize {
        @challenge[uri] = parse_challenge_param(param_str)
        true
      }
    end

  private

    # this method is implemented by sromano and posted to
    # http://tools.assembla.com/breakout/wiki/DigestForSoap
    # Thanks!
    # supported algorithms: MD5, MD5-sess
    def calc_cred(req, user, passwd, param)
      method = req.header.request_method
      path = req.header.create_query_uri
      a_1 = "#{user}:#{param['realm']}:#{passwd}"
      a_2 = "#{method}:#{path}"
      qop = param['qop']
      nonce = param['nonce']
      cnonce = nil
      if qop || param['algorithm'] =~ /MD5-sess/
        cnonce = generate_cnonce()
      end
      a_1_md5sum = Digest::MD5.hexdigest(a_1)
      if param['algorithm'] =~ /MD5-sess/
        a_1_md5sum = Digest::MD5.hexdigest("#{a_1_md5sum}:#{nonce}:#{cnonce}")
        algorithm = "MD5-sess"
      else
        algorithm = "MD5"
      end
      message_digest = []
      message_digest << a_1_md5sum
      message_digest << nonce
      if qop
        @nonce_count += 1
        message_digest << ('%08x' % @nonce_count)
        message_digest << cnonce
        message_digest << param['qop']
      end
      message_digest << Digest::MD5.hexdigest(a_2)
      header = []
      header << "username=\"#{user}\""
      header << "realm=\"#{param['realm']}\""
      header << "nonce=\"#{nonce}\""
      header << "uri=\"#{path}\""
      if cnonce
        header << "cnonce=\"#{cnonce}\""
      end
      if qop
        header << "nc=#{'%08x' % @nonce_count}"
        header << "qop=#{param['qop']}"
      end
      header << "response=\"#{Digest::MD5.hexdigest(message_digest.join(":"))}\""
      header << "algorithm=#{algorithm}"
      header << "opaque=\"#{param['opaque']}\"" if param.key?('opaque')
      header.join(", ")
    end

    # cf. WEBrick::HTTPAuth::DigestAuth#generate_next_nonce(aTime)
    def generate_cnonce
      now = "%012d" % Time.now.to_i
      pk = Digest::MD5.hexdigest([now, self.__id__, Process.pid, rand(65535)].join)[0, 32]
      [now + ':' + pk].pack('m*').chop
    end

    def parse_challenge_param(param_str)
      param = {}
      param_str.scan(/\s*([^\,]+(?:\\.[^\,]*)*)/).each do |str|
        key, value = str[0].scan(/\A([^=]+)=(.*)\z/)[0]
        if /\A"(.*)"\z/ =~ value
          value = $1.gsub(/\\(.)/, '\1')
        end
        param[key] = value
      end
      param
    end
  end


  # Authentication filter for handling DigestAuth negotiation.
  # Ignores uri argument. Used in ProxyAuth.
  class ProxyDigestAuth < DigestAuth

    # overrides DigestAuth#set. sets default user name and password. uri is not used.
    def set(uri, user, passwd)
      synchronize do
        @auth = [user, passwd]
      end
    end

    # overrides DigestAuth#get. Uses default user name and password
    # regardless of target uri if the proxy has required authentication
    # before
    def get(req)
      synchronize {
        param = @challenge
        return nil unless param
        user, passwd = @auth
        return nil unless user
        calc_cred(req, user, passwd, param)
      }
    end

    def reset_challenge
      synchronize do
        @challenge = nil
      end
    end

    def challenge(uri, param_str)
      synchronize {
        @challenge = parse_challenge_param(param_str)
        true
      }
    end
  end

  # Authentication filter for handling Negotiate/NTLM negotiation.
  # Used in WWWAuth and ProxyAuth.
  #
  # NegotiateAuth depends on 'ruby/ntlm' module.
  class NegotiateAuth < AuthBase
    include Mutex_m

    # NTLM opt for ruby/ntlm.  {:ntlmv2 => true} by default.
    attr_reader :ntlm_opt

    # Creates new NegotiateAuth filter.
    def initialize(scheme = "Negotiate")
      super(scheme)
      @auth = {}
      @auth_default = nil
      @ntlm_opt = {
        :ntlmv2 => true
      }
    end

    # Set authentication credential.
    # uri == nil for generic purpose (allow to use user/password for any URL).
    def set(uri, user, passwd)
      synchronize do
        if uri
          uri = Util.uri_dirname(uri)
          @auth[uri] = [user, passwd]
        else
          @auth_default = [user, passwd]
        end
      end
    end

    # have we marked this as set - ie that it's valid to use in this context?
    def set?
      @auth_default || @auth.any?
    end

    # Response handler: returns credential.
    # See ruby/ntlm for negotiation state transition.
    def get(req)
      target_uri = req.header.request_uri
      synchronize {
        _domain_uri, param = @challenge.find { |uri, v|
          Util.uri_part_of(target_uri, uri)
        }
        return nil unless param
        user, passwd = Util.hash_find_value(@auth) { |uri, auth_data|
          Util.uri_part_of(target_uri, uri)
        }
        unless user
          user, passwd = @auth_default
        end
        return nil unless user
        Util.try_require('net/ntlm') || return
        domain = nil
        domain, user = user.split("\\") if user.index("\\")
        state = param[:state]
        authphrase = param[:authphrase]
        case state
        when :init
          t1 = Net::NTLM::Message::Type1.new
          t1.domain = domain if domain
          t1.encode64
        when :response
          t2 = Net::NTLM::Message.decode64(authphrase)
          param = {:user => user, :password => passwd}
          param[:domain] = domain if domain
          t3 = t2.response(param, @ntlm_opt.dup)
          @challenge[target_uri][:state] = :done
          t3.encode64
        when :done
          :skip
        else
          nil
        end
      }
    end

    # Challenge handler: remember URL and challenge token for response.
    def challenge(uri, param_str)
      synchronize {
        if param_str.nil? or @challenge[uri].nil?
          c = @challenge[uri] = {}
          c[:state] = :init
          c[:authphrase] = ""
        else
          c = @challenge[uri]
          c[:state] = :response
          c[:authphrase] = param_str
        end
        true
      }
    end
  end


  # Authentication filter for handling Negotiate/NTLM negotiation.
  # Used in ProxyAuth.
  #
  # SSPINegotiateAuth depends on 'win32/sspi' module.
  class SSPINegotiateAuth < AuthBase
    include Mutex_m

    # Creates new SSPINegotiateAuth filter.
    def initialize
      super('Negotiate')
    end

    # Set authentication credential.
    # NOT SUPPORTED: username and necessary data is retrieved by win32/sspi.
    # See win32/sspi for more details.
    def set(*args)
      # not supported
    end

    # Check always (not effective but it works)
    def set?
      !@challenge.empty?
    end

    # Response handler: returns credential.
    # See win32/sspi for negotiation state transition.
    def get(req)
      target_uri = req.header.request_uri
      synchronize {
        domain_uri, param = @challenge.find { |uri, v|
          Util.uri_part_of(target_uri, uri)
        }
        return nil unless param
        Util.try_require('win32/sspi') || Util.try_require('gssapi') || return
        state = param[:state]
        authenticator = param[:authenticator]
        authphrase = param[:authphrase]
        case state
        when :init
          if defined?(Win32::SSPI)
            authenticator = param[:authenticator] = Win32::SSPI::NegotiateAuth.new
            authenticator.get_initial_token(@scheme)
          else # use GSSAPI
            authenticator = param[:authenticator] = GSSAPI::Simple.new(domain_uri.host, 'HTTP')
            # Base64 encode the context token
            [authenticator.init_context].pack('m').gsub(/\n/,'')
          end
        when :response
          @challenge[target_uri][:state] = :done
          if defined?(Win32::SSPI)
            authenticator.complete_authentication(authphrase)
          else # use GSSAPI
            authenticator.init_context(authphrase.unpack('m').pop)
          end
        when :done
          :skip
        else
          nil
        end
      }
    end

    # Challenge handler: remember URL and challenge token for response.
    def challenge(uri, param_str)
      synchronize {
        if param_str.nil? or @challenge[uri].nil?
          c = @challenge[uri] = {}
          c[:state] = :init
          c[:authenticator] = nil
          c[:authphrase] = ""
        else
          c = @challenge[uri]
          c[:state] = :response
          c[:authphrase] = param_str
        end
        true
      }
    end
  end

  # Authentication filter for handling OAuth negotiation.
  # Used in WWWAuth.
  #
  # CAUTION: This impl only support '#7 Accessing Protected Resources' in OAuth
  # Core 1.0 spec for now. You need to obtain Access token and Access secret by
  # yourself.
  #
  # CAUTION: This impl does NOT support OAuth Request Body Hash spec for now.
  # http://oauth.googlecode.com/svn/spec/ext/body_hash/1.0/oauth-bodyhash.html
  #
  class OAuth < AuthBase
    include Mutex_m

    class Config
      include HTTPClient::Util

      attr_accessor :http_method
      attr_accessor :realm
      attr_accessor :consumer_key
      attr_accessor :consumer_secret
      attr_accessor :token
      attr_accessor :secret
      attr_accessor :signature_method
      attr_accessor :version
      attr_accessor :callback
      attr_accessor :verifier

      # for OAuth Session 1.0 (draft)
      attr_accessor :session_handle

      attr_reader :signature_handler

      attr_accessor :debug_timestamp
      attr_accessor :debug_nonce

      def initialize(*args)
        @http_method,
          @realm,
          @consumer_key,
          @consumer_secret,
          @token,
          @secret,
          @signature_method,
          @version,
          @callback,
          @verifier =
        keyword_argument(args,
          :http_method,
          :realm,
          :consumer_key,
          :consumer_secret,
          :token,
          :secret,
          :signature_method,
          :version,
          :callback,
          :verifier
        )
        @http_method ||= :post
        @session_handle = nil
        @signature_handler = {}
      end
    end

    def self.escape(str) # :nodoc:
      if str.respond_to?(:force_encoding)
        str.dup.force_encoding('BINARY').gsub(/([^a-zA-Z0-9_.~-]+)/) {
          '%' + $1.unpack('H2' * $1.bytesize).join('%').upcase
        }
      else
        str.gsub(/([^a-zA-Z0-9_.~-]+)/n) {
          '%' + $1.unpack('H2' * $1.bytesize).join('%').upcase
        }
      end
    end

    def escape(str)
      self.class.escape(str)
    end

    # Creates new DigestAuth filter.
    def initialize
      super('OAuth')
      @config = nil # common config
      @auth = {} # configs for each site
      @nonce_count = 0
      @signature_handler = {
        'HMAC-SHA1' => method(:sign_hmac_sha1)
      }
    end

    # Set authentication credential.
    # You cannot set OAuth config via WWWAuth#set_auth. Use OAuth#config=
    def set(*args)
      # not supported
    end

    # Check always (not effective but it works)
    def set?
      !@challenge.empty?
    end

    # Set authentication credential.
    def set_config(uri, config)
      synchronize do
        if uri.nil?
          @config = config
        else
          uri = Util.uri_dirname(urify(uri))
          @auth[uri] = config
        end
      end
    end

    # Get authentication credential.
    def get_config(uri = nil)
      synchronize {
        do_get_config(uri)
      }
    end

    # Response handler: returns credential.
    # It sends cred only when a given uri is;
    # * child page of challengeable(got *Authenticate before) uri and,
    # * child page of defined credential
    def get(req)
      target_uri = req.header.request_uri
      synchronize {
        return nil unless @challenge[nil] or @challenge.find { |uri, ok|
          Util.uri_part_of(target_uri, uri) and ok
        }
        config = do_get_config(target_uri) || @config
        return nil unless config
        calc_cred(req, config)
      }
    end

    # Challenge handler: remember URL for response.
    #
    # challenge() in OAuth handler always returns false to avoid connection
    # retry which should not work in OAuth authentication context.  This
    # method just remember URL (nil means 'any') for the next connection.
    # Normally OAuthClient handles this correctly but see how it uses when
    # you need to use this class directly.
    def challenge(uri, param_str = nil)
      synchronize {
        if uri.nil?
          @challenge[nil] = true
        else
          @challenge[urify(uri)] = true
        end
        false
      }
    end

  private

    def do_get_config(uri = nil)
      if uri.nil?
        @config
      else
        uri = urify(uri)
        Util.hash_find_value(@auth) { |cand_uri, cred|
          Util.uri_part_of(uri, cand_uri)
        }
      end
    end

    def calc_cred(req, config)
      header = {}
      header['oauth_consumer_key'] = config.consumer_key
      header['oauth_signature_method'] = config.signature_method
      header['oauth_timestamp'] = config.debug_timestamp || Time.now.to_i.to_s
      header['oauth_nonce'] = config.debug_nonce || generate_nonce()
      header['oauth_token'] = config.token if config.token
      header['oauth_version'] = config.version if config.version
      header['oauth_callback'] = config.callback if config.callback
      header['oauth_verifier'] = config.verifier if config.verifier
      header['oauth_session_handle'] = config.session_handle if config.session_handle
      signature = sign(config, header, req)
      header['oauth_signature'] = signature
      # no need to do but we should sort for easier to test.
      str = header.sort_by { |k, v| k }.map { |k, v| encode_header(k, v) }.join(', ')
      if config.realm
        str = %Q(realm="#{config.realm}", ) + str
      end
      str
    end

    def generate_nonce
      @nonce_count += 1
      now = "%012d" % Time.now.to_i
      pk = Digest::MD5.hexdigest([@nonce_count.to_s, now, self.__id__, Process.pid, rand(65535)].join)[0, 32]
      [now + ':' + pk].pack('m*').chop
    end

    def encode_header(k, v)
      %Q(#{escape(k.to_s)}="#{escape(v.to_s)}")
    end

    def encode_param(params)
      params.map { |k, v|
        [v].flatten.map { |vv|
          %Q(#{escape(k.to_s)}=#{escape(vv.to_s)})
        }
      }.flatten
    end

    def sign(config, header, req)
      base_string = create_base_string(config, header, req)
      if handler = config.signature_handler[config.signature_method] || @signature_handler[config.signature_method.to_s]
        handler.call(config, base_string)
      else
        raise ConfigurationError.new("Unknown OAuth signature method: #{config.signature_method}")
      end
    end

    def create_base_string(config, header, req)
      params = encode_param(header)
      query = req.header.request_query
      if query and HTTP::Message.multiparam_query?(query)
        params += encode_param(query)
      end
      # captures HTTP Message body only for 'application/x-www-form-urlencoded'
      if req.header.contenttype == 'application/x-www-form-urlencoded' and req.http_body.size
        params += encode_param(HTTP::Message.parse(req.http_body.content))
      end
      uri = req.header.request_uri
      if uri.query
        params += encode_param(HTTP::Message.parse(uri.query))
      end
      if uri.port == uri.default_port
        request_url = "#{uri.scheme.downcase}://#{uri.host}#{uri.path}"
      else
        request_url = "#{uri.scheme.downcase}://#{uri.host}:#{uri.port}#{uri.path}"
      end
      [req.header.request_method.upcase, request_url, params.sort.join('&')].map { |e|
        escape(e)
      }.join('&')
    end

    def sign_hmac_sha1(config, base_string)
      unless SSLEnabled
        raise ConfigurationError.new("openssl required for OAuth implementation")
      end
      key = [escape(config.consumer_secret.to_s), escape(config.secret.to_s)].join('&')
      digester = OpenSSL::Digest::SHA1.new
      [OpenSSL::HMAC.digest(digester, key, base_string)].pack('m*').chomp
    end
  end


end