require 'action_dispatch' module ActionCable module Connection # For every WebSocket the cable server is accepting, a Connection object will be instantiated. This instance becomes the parent # of all the channel subscriptions that are created from there on. Incoming messages are then routed to these channel subscriptions # based on an identifier sent by the cable consumer. The Connection itself does not deal with any specific application logic beyond # authentication and authorization. # # Here's a basic example: # # module ApplicationCable # class Connection < ActionCable::Connection::Base # identified_by :current_user # # def connect # self.current_user = find_verified_user # logger.add_tags current_user.name # end # # def disconnect # # Any cleanup work needed when the cable connection is cut. # end # # protected # def find_verified_user # if current_user = User.find_by_identity cookies.signed[:identity_id] # current_user # else # reject_unauthorized_connection # end # end # end # end # # First, we declare that this connection can be identified by its current_user. This allows us later to be able to find all connections # established for that current_user (and potentially disconnect them if the user was removed from an account). You can declare as many # identification indexes as you like. Declaring an identification means that a attr_accessor is automatically set for that key. # # Second, we rely on the fact that the WebSocket connection is established with the cookies from the domain being sent along. This makes # it easy to use signed cookies that were set when logging in via a web interface to authorize the WebSocket connection. # # Finally, we add a tag to the connection-specific logger with name of the current user to easily distinguish their messages in the log. # # Pretty simple, eh? class Base include Identification include InternalChannel include Authorization attr_reader :server, :env, :subscriptions, :logger delegate :worker_pool, :pubsub, to: :server def initialize(server, env) @server, @env = server, env @logger = new_tagged_logger @websocket = ActionCable::Connection::WebSocket.new(env) @subscriptions = ActionCable::Connection::Subscriptions.new(self) @message_buffer = ActionCable::Connection::MessageBuffer.new(self) @_internal_redis_subscriptions = nil @started_at = Time.now end # Called by the server when a new WebSocket connection is established. This configures the callbacks intended for overwriting by the user. # This method should not be called directly. Rely on the #connect (and #disconnect) callback instead. def process logger.info started_request_message if websocket.possible? && allow_request_origin? websocket.on(:open) { |event| send_async :on_open } websocket.on(:message) { |event| on_message event.data } websocket.on(:close) { |event| send_async :on_close } respond_to_successful_request else respond_to_invalid_request end end # Data received over the cable is handled by this method. It's expected that everything inbound is JSON encoded. # The data is routed to the proper channel that the connection has subscribed to. def receive(data_in_json) if websocket.alive? subscriptions.execute_command ActiveSupport::JSON.decode(data_in_json) else logger.error "Received data without a live WebSocket (#{data_in_json.inspect})" end end # Send raw data straight back down the WebSocket. This is not intended to be called directly. Use the #transmit available on the # Channel instead, as that'll automatically address the correct subscriber and wrap the message in JSON. def transmit(data) websocket.transmit data end # Close the WebSocket connection. def close websocket.close end # Invoke a method on the connection asynchronously through the pool of thread workers. def send_async(method, *arguments) worker_pool.async.invoke(self, method, *arguments) end # Return a basic hash of statistics for the connection keyed with `identifier`, `started_at`, and `subscriptions`. # This can be returned by a health check against the connection. def statistics { identifier: connection_identifier, started_at: @started_at, subscriptions: subscriptions.identifiers, request_id: @env['action_dispatch.request_id'] } end def beat transmit ActiveSupport::JSON.encode(identifier: ActionCable::INTERNAL[:identifiers][:ping], message: Time.now.to_i) end protected # The request that initiated the WebSocket connection is available here. This gives access to the environment, cookies, etc. def request @request ||= begin environment = Rails.application.env_config.merge(env) if defined?(Rails.application) && Rails.application ActionDispatch::Request.new(environment || env) end end # The cookies of the request that initiated the WebSocket connection. Useful for performing authorization checks. def cookies request.cookie_jar end attr_reader :websocket attr_reader :message_buffer private def on_open connect if respond_to?(:connect) subscribe_to_internal_channel beat message_buffer.process! server.add_connection(self) rescue ActionCable::Connection::Authorization::UnauthorizedError respond_to_invalid_request end def on_message(message) message_buffer.append message end def on_close logger.info finished_request_message server.remove_connection(self) subscriptions.unsubscribe_from_all unsubscribe_from_internal_channel disconnect if respond_to?(:disconnect) end def allow_request_origin? return true if server.config.disable_request_forgery_protection if Array(server.config.allowed_request_origins).any? { |allowed_origin| allowed_origin === env['HTTP_ORIGIN'] } true else logger.error("Request origin not allowed: #{env['HTTP_ORIGIN']}") false end end def respond_to_successful_request websocket.rack_response end def respond_to_invalid_request close if websocket.alive? logger.info finished_request_message [ 404, { 'Content-Type' => 'text/plain' }, [ 'Page not found' ] ] end # Tags are declared in the server but computed in the connection. This allows us per-connection tailored tags. def new_tagged_logger TaggedLoggerProxy.new server.logger, tags: server.config.log_tags.map { |tag| tag.respond_to?(:call) ? tag.call(request) : tag.to_s.camelize } end def started_request_message 'Started %s "%s"%s for %s at %s' % [ request.request_method, request.filtered_path, websocket.possible? ? ' [WebSocket]' : '', request.ip, Time.now.to_s ] end def finished_request_message 'Finished "%s"%s for %s at %s' % [ request.filtered_path, websocket.possible? ? ' [WebSocket]' : '', request.ip, Time.now.to_s ] end end end end