stripe-ruby/lib/stripe/stripe_client.rb

module Stripe
  # StripeClient executes requests against the Stripe API and allows a user to
  # recover both a resource a call returns as well as a response object that
  # contains information on the HTTP call.
  class StripeClient
    attr_accessor :conn

    # Initializes a new StripeClient. Expects a Faraday connection object, and
    # uses a default connection unless one is passed.
    def initialize(conn = nil)
      self.conn = conn || self.class.default_conn
      @system_profiler = SystemProfiler.new
    end

    def self.active_client
      Thread.current[:stripe_client] || default_client
    end

    def self.default_client
      @default_client ||= StripeClient.new(default_conn)
    end

    # A default Faraday connection to be used when one isn't configured. This
    # object should never be mutated, and instead instantiating your own
    # connection and wrapping it in a StripeClient object should be preferred.
    def self.default_conn
      # We're going to keep connections around so that we can take advantage
      # of connection re-use, so make sure that we have a separate connection
      # object per thread.
      Thread.current[:stripe_client_default_conn] ||= begin
        conn = Faraday.new do |c|
          c.use Faraday::Request::Multipart
          c.use Faraday::Request::UrlEncoded
          c.use Faraday::Response::RaiseError
          c.adapter Faraday.default_adapter
        end

        if Stripe.verify_ssl_certs
          conn.ssl.verify = true
          conn.ssl.cert_store = Stripe.ca_store
        else
          conn.ssl.verify = false

          unless @verify_ssl_warned
            @verify_ssl_warned = true
            $stderr.puts("WARNING: Running without SSL cert verification. " \
              "You should never do this in production. " \
              "Execute 'Stripe.verify_ssl_certs = true' to enable verification.")
          end
        end

        conn
      end
    end

    # Checks if an error is a problem that we should retry on. This includes both
    # socket errors that may represent an intermittent problem and some special
    # HTTP statuses.
    def self.should_retry?(e, num_retries)
      return false if num_retries >= Stripe.max_network_retries

      # Retry on timeout-related problems (either on open or read).
      return true if e.is_a?(Faraday::TimeoutError)

      # Destination refused the connection, the connection was reset, or a
      # variety of other connection failures. This could occur from a single
      # saturated server, so retry in case it's intermittent.
      return true if e.is_a?(Faraday::ConnectionFailed)

      if e.is_a?(Faraday::ClientError) && e.response
        # 409 conflict
        return true if e.response[:status] == 409
      end

      false
    end

    def self.sleep_time(num_retries)
      # Apply exponential backoff with initial_network_retry_delay on the
      # number of num_retries so far as inputs. Do not allow the number to exceed
      # max_network_retry_delay.
      sleep_seconds = [Stripe.initial_network_retry_delay * (2 ** (num_retries - 1)), Stripe.max_network_retry_delay].min

      # Apply some jitter by randomizing the value in the range of (sleep_seconds
      # / 2) to (sleep_seconds).
      sleep_seconds = sleep_seconds * (0.5 * (1 + rand()))

      # But never sleep less than the base sleep seconds.
      sleep_seconds = [Stripe.initial_network_retry_delay, sleep_seconds].max

      sleep_seconds
    end

    # Executes the API call within the given block. Usage looks like:
    #
    #     client = StripeClient.new
    #     charge, resp = client.request { Charge.create }
    #
    def request(&block)
      @last_response = nil
      old_stripe_client = Thread.current[:stripe_client]
      Thread.current[:stripe_client] = self

      begin
        res = block.call
        [res, @last_response]
      ensure
        Thread.current[:stripe_client] = old_stripe_client
      end
    end

    def execute_request(method, path,
        api_base: nil, api_key: nil, headers: {}, params: {})

      api_base ||= Stripe.api_base
      api_key ||= Stripe.api_key

      check_api_key!(api_key)

      params = Util.objects_to_ids(params)
      url = api_url(path, api_base)

      case method.to_s.downcase.to_sym
      when :get, :head, :delete
        # Make params into GET parameters
        url += "#{URI.parse(url).query ? '&' : '?'}#{Util.encode_parameters(params)}" if params && params.any?
        payload = nil
      else
        if headers[:content_type] && headers[:content_type] == "multipart/form-data"
          payload = params
        else
          payload = Util.encode_parameters(params)
        end
      end

      headers = request_headers(api_key, method).
        update(Util.normalize_headers(headers))

      # stores information on the request we're about to make so that we don't
      # have to pass as many parameters around for logging.
      context = RequestLogContext.new(
        account: headers["Stripe-Account"],
        api_key: api_key,
        api_version: headers["Stripe-Version"],
        idempotency_key: headers["Idempotency-Key"],
        method: method,
        path: path,
        payload: payload,
      )

      http_resp = execute_request_with_rescues(api_base, context) do
        conn.run_request(method, url, payload, headers) do |req|
          req.options.open_timeout = Stripe.open_timeout
          req.options.timeout = Stripe.read_timeout
        end
      end

      begin
        resp = StripeResponse.from_faraday_response(http_resp)
      rescue JSON::ParserError
        raise general_api_error(http_resp.status, http_resp.body)
      end

      # Allows StripeClient#request to return a response object to a caller.
      @last_response = resp
      [resp, api_key]
    end

    private

    def api_url(url='', api_base=nil)
      (api_base || Stripe.api_base) + url
    end

    def check_api_key!(api_key)
      unless api_key
        raise AuthenticationError.new('No API key provided. ' \
          'Set your API key using "Stripe.api_key = <API-KEY>". ' \
          'You can generate API keys from the Stripe web interface. ' \
          'See https://stripe.com/api for details, or email support@stripe.com ' \
          'if you have any questions.')
      end

      if api_key =~ /\s/
        raise AuthenticationError.new('Your API key is invalid, as it contains ' \
          'whitespace. (HINT: You can double-check your API key from the ' \
          'Stripe web interface. See https://stripe.com/api for details, or ' \
          'email support@stripe.com if you have any questions.)')
      end
    end

    def execute_request_with_rescues(api_base, context, &block)
      num_retries = 0
      begin
        request_start = Time.now
        log_request(context, num_retries)
        resp = block.call
        context = context.dup_from_response(resp)
        log_response(context, request_start, resp.status, resp.body)

      # We rescue all exceptions from a request so that we have an easy spot to
      # implement our retry logic across the board. We'll re-raise if it's a type
      # of exception that we didn't expect to handle.
      rescue => e
        # If we modify context we copy it into a new variable so as not to
        # taint the original on a retry.
        error_context = context

        if e.respond_to?(:response) && e.response
          error_context = context.dup_from_response(e.response)
          log_response(error_context, request_start,
            e.response[:status], e.response[:body])
        else
          log_response_error(error_context, request_start, e)
        end

        if self.class.should_retry?(e, num_retries)
          num_retries += 1
          sleep self.class.sleep_time(num_retries)
          retry
        end

        case e
        when Faraday::ClientError
          if e.response
            handle_error_response(e.response, error_context)
          else
            handle_network_error(e, error_context, num_retries, api_base)
          end

        # Only handle errors when we know we can do so, and re-raise otherwise.
        # This should be pretty infrequent.
        else
          raise
        end
      end

      resp
    end

    def general_api_error(status, body)
      APIError.new("Invalid response object from API: #{body.inspect} " +
                   "(HTTP response code was #{status})",
                   http_status: status, http_body: body)
    end

    # Formats a plugin "app info" hash into a string that we can tack onto the
    # end of a User-Agent string where it'll be fairly prominant in places like
    # the Dashboard. Note that this formatting has been implemented to match
    # other libraries, and shouldn't be changed without universal consensus.
    def format_app_info(info)
      str = info[:name]
      str = "#{str}/#{info[:version]}" unless info[:version].nil?
      str = "#{str} (#{info[:url]})" unless info[:url].nil?
      str
    end

    def handle_error_response(http_resp, context)
      begin
        resp = StripeResponse.from_faraday_hash(http_resp)
        error_data = resp.data[:error]

        unless error_data
          raise StripeError.new("Indeterminate error")
        end

      rescue JSON::ParserError, StripeError
        raise general_api_error(http_resp[:status], http_resp[:body])
      end

      if error_data.is_a?(String)
        error = specific_oauth_error(resp, error_data, context)
      else
        error = specific_api_error(resp, error_data, context)
      end

      error.response = resp
      raise(error)
    end

    def specific_api_error(resp, error_data, context)
      Util.log_info('Stripe API error',
        status: resp.http_status,
        error_code: error_data['code'],
        error_message: error_data['message'],
        error_param: error_data['param'],
        error_type: error_data['type'],
        idempotency_key: context.idempotency_key,
        request_id: context.request_id
      )

      case resp.http_status
      when 400, 404
        error = InvalidRequestError.new(
          error_data[:message], error_data[:param],
          http_status: resp.http_status, http_body: resp.http_body,
          json_body: resp.data, http_headers: resp.http_headers
        )
      when 401
        error = AuthenticationError.new(
          error_data[:message],
          http_status: resp.http_status, http_body: resp.http_body,
          json_body: resp.data, http_headers: resp.http_headers
        )
      when 402
        error = CardError.new(
          error_data[:message], error_data[:param], error_data[:code],
          http_status: resp.http_status, http_body: resp.http_body,
          json_body: resp.data, http_headers: resp.http_headers
        )
      when 403
        error = PermissionError.new(
          error_data[:message],
          http_status: resp.http_status, http_body: resp.http_body,
          json_body: resp.data, http_headers: resp.http_headers
        )
      when 429
        error = RateLimitError.new(
          error_data[:message],
          http_status: resp.http_status, http_body: resp.http_body,
          json_body: resp.data, http_headers: resp.http_headers
        )
      else
        error = APIError.new(
          error_data[:message],
          http_status: resp.http_status, http_body: resp.http_body,
          json_body: resp.data, http_headers: resp.http_headers
        )
      end

      error
    end

    # Attempts to look at a response's error code and return an OAuth error if
    # one matches. Will return `nil` if the code isn't recognized.
    def specific_oauth_error(resp, error_code, context)
      description = resp.data[:error_description] || error_code

      Util.log_info('Stripe OAuth error',
        status: resp.http_status,
        error_code: error_code,
        error_description: description,
        idempotency_key: context.idempotency_key,
        request_id: context.request_id
      )

      args = [error_code, description, {
        http_status: resp.http_status, http_body: resp.http_body,
        json_body: resp.data, http_headers: resp.http_headers
      }]

      case error_code
      when 'invalid_client'            then OAuth::InvalidClientError.new(*args)
      when 'invalid_grant'             then OAuth::InvalidGrantError.new(*args)
      when 'invalid_request'           then OAuth::InvalidRequestError.new(*args)
      when 'invalid_scope'             then OAuth::InvalidScopeError.new(*args)
      when 'unsupported_grant_type'    then OAuth::UnsupportedGrantTypeError.new(*args)
      when 'unsupported_response_type' then OAuth::UnsupportedResponseTypeError.new(*args)
      else
        # We'd prefer that all errors are typed, but we create a generic
        # OAuthError in case we run into a code that we don't recognize.
        OAuth::OAuthError.new(*args)
      end
    end

    def handle_network_error(e, context, num_retries, api_base=nil)
      Util.log_info('Stripe OAuth error',
        error_message: e.message,
        idempotency_key: context.idempotency_key,
        request_id: context.request_id
      )

      case e
      when Faraday::ConnectionFailed
        message = "Unexpected error communicating when trying to connect to Stripe. " \
          "You may be seeing this message because your DNS is not working. " \
          "To check, try running 'host stripe.com' from the command line."

      when Faraday::SSLError
        message = "Could not establish a secure connection to Stripe, you may " \
                  "need to upgrade your OpenSSL version. To check, try running " \
                  "'openssl s_client -connect api.stripe.com:443' from the " \
                  "command line."

      when Faraday::TimeoutError
        api_base = Stripe.api_base unless api_base
        message = "Could not connect to Stripe (#{api_base}). " \
          "Please check your internet connection and try again. " \
          "If this problem persists, you should check Stripe's service status at " \
          "https://twitter.com/stripestatus, or let us know at support@stripe.com."

      else
        message = "Unexpected error communicating with Stripe. " \
          "If this problem persists, let us know at support@stripe.com."

      end

      if num_retries > 0
        message += " Request was retried #{num_retries} times."
      end

      raise APIConnectionError.new(message + "\n\n(Network error: #{e.message})")
    end

    def request_headers(api_key, method)
      user_agent = "Stripe/v1 RubyBindings/#{Stripe::VERSION}"
      unless Stripe.app_info.nil?
        user_agent += " " + format_app_info(Stripe.app_info)
      end

      headers = {
        'User-Agent' => user_agent,
        'Authorization' => "Bearer #{api_key}",
        'Content-Type' => 'application/x-www-form-urlencoded'
      }

      # It is only safe to retry network failures on post and delete
      # requests if we add an Idempotency-Key header
      if [:post, :delete].include?(method) && Stripe.max_network_retries > 0
        headers['Idempotency-Key'] ||= SecureRandom.uuid
      end

      headers['Stripe-Version'] = Stripe.api_version if Stripe.api_version
      headers['Stripe-Account'] = Stripe.stripe_account if Stripe.stripe_account

      user_agent = @system_profiler.user_agent
      begin
        headers.update(
          'X-Stripe-Client-User-Agent' => JSON.generate(user_agent)
        )
      rescue => e
        headers.update(
          'X-Stripe-Client-Raw-User-Agent' => user_agent.inspect,
          :error => "#{e} (#{e.class})"
        )
      end

      headers
    end

    def log_request(context, num_retries)
      Util.log_info("Request to Stripe API",
        account: context.account,
        api_version: context.api_version,
        idempotency_key: context.idempotency_key,
        method: context.method,
        num_retries: num_retries,
        path: context.path
      )
      Util.log_debug("Request details",
        body: context.payload,
        idempotency_key: context.idempotency_key
      )
    end
    private :log_request

    def log_response(context, request_start, status, body)
      Util.log_info("Response from Stripe API",
        account: context.account,
        api_version: context.api_version,
        elapsed: Time.now - request_start,
        idempotency_key: context.idempotency_key,
        method: context.method,
        path: context.path,
        request_id: context.request_id,
        status: status
      )
      Util.log_debug("Response details",
        body: body,
        idempotency_key: context.idempotency_key,
        request_id: context.request_id,
      )
      if context.request_id
        Util.log_debug("Dashboard link for request",
          idempotency_key: context.idempotency_key,
          request_id: context.request_id,
          url: Util.request_id_dashboard_url(context.request_id, context.api_key)
        )
      end
    end
    private :log_response

    def log_response_error(context, request_start, e)
      Util.log_info("Request error",
        elapsed: Time.now - request_start,
        error_message: e.message,
        idempotency_key: context.idempotency_key,
        method: context.method,
        path: context.path,
      )
    end
    private :log_response_error

    # RequestLogContext stores information about a request that's begin made so
    # that we can log certain information. It's useful because it means that we
    # don't have to pass around as many parameters.
    class RequestLogContext
      attr_accessor :account
      attr_accessor :api_key
      attr_accessor :api_version
      attr_accessor :idempotency_key
      attr_accessor :method
      attr_accessor :path
      attr_accessor :payload
      attr_accessor :request_id

      def initialize(account: nil, api_key: nil, api_version: nil,
          idempotency_key: nil, method: nil, path: nil, payload: nil)
        self.account = account
        self.api_key = api_key
        self.api_version = api_version
        self.idempotency_key = idempotency_key
        self.method = method
        self.path = path
        self.payload = payload
      end

      # The idea with this method is that we might want to update some of
      # context information because a response that we've received from the API
      # contains information that's more authoritative than what we started
      # with for a request. For example, we should trust whatever came back in
      # a `Stripe-Version` header beyond what configuration information that we
      # might have had available.
      def dup_from_response(resp)
        return self if resp.nil?

        # Faraday's API is a little unusual. Normally it'll produce a response
        # object with a `headers` method, but on error what it puts into
        # `e.response` is an untyped `Hash`.
        headers = if resp.is_a?(Faraday::Response)
          resp.headers
        else
          resp[:headers]
        end

        context = self.dup
        context.account = headers["Stripe-Account"]
        context.api_version = headers["Stripe-Version"]
        context.idempotency_key = headers["Idempotency-Key"]
        context.request_id = headers["Request-Id"]
        context
      end
    end

    # SystemProfiler extracts information about the system that we're running
    # in so that we can generate a rich user agent header to help debug
    # integrations.
    class SystemProfiler
      def self.get_uname
        if File.exist?('/proc/version')
          File.read('/proc/version').strip
        else
          case RbConfig::CONFIG['host_os']
          when /linux|darwin|bsd|sunos|solaris|cygwin/i
            get_uname_from_system
          when /mswin|mingw/i
            get_uname_from_system_ver
          else
            "unknown platform"
          end
        end
      end

      def self.get_uname_from_system
        (`uname -a 2>/dev/null` || '').strip
      rescue Errno::ENOENT
        "uname executable not found"
      rescue Errno::ENOMEM # couldn't create subprocess
        "uname lookup failed"
      end

      def self.get_uname_from_system_ver
        (`ver` || '').strip
      rescue Errno::ENOENT
        "ver executable not found"
      rescue Errno::ENOMEM # couldn't create subprocess
        "uname lookup failed"
      end

      def initialize
        @uname = self.class.get_uname
      end

      def user_agent
        lang_version = "#{RUBY_VERSION} p#{RUBY_PATCHLEVEL} (#{RUBY_RELEASE_DATE})"

        {
          :application => Stripe.app_info,
          :bindings_version => Stripe::VERSION,
          :lang => 'ruby',
          :lang_version => lang_version,
          :platform => RUBY_PLATFORM,
          :engine => defined?(RUBY_ENGINE) ? RUBY_ENGINE : '',
          :publisher => 'stripe',
          :uname => @uname,
          :hostname => Socket.gethostname,
        }.delete_if { |k, v| v.nil? }
      end
    end
  end
end