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# frozen_string_literal: true
require "action_dispatch"
module ActionCable
module Connection
# For every WebSocket connection the Action Cable server accepts, a Connection object will be instantiated. This instance becomes the parent
# of all of 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 Action 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
#
# private
# def find_verified_user
# User.find_by_identity(cookies.encrypted[:identity_id]) ||
# reject_unauthorized_connection
# end
# end
# end
#
# First, we declare that this connection can be identified by its current_user. This allows us to later be able to find all connections
# established for that current_user (and potentially disconnect them). You can declare as many
# identification indexes as you like. Declaring an identification means that an 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 the 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, :worker_pool, :protocol
delegate :event_loop, :pubsub, to: :server
def initialize(server, env, coder: ActiveSupport::JSON)
@server, @env, @coder = server, env, coder
@worker_pool = server.worker_pool
@logger = new_tagged_logger
@websocket = ActionCable::Connection::WebSocket.new(env, self, event_loop)
@subscriptions = ActionCable::Connection::Subscriptions.new(self)
@message_buffer = ActionCable::Connection::MessageBuffer.new(self)
@_internal_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 -- instead rely upon on the #connect (and #disconnect) callbacks.
def process #:nodoc:
logger.info started_request_message
if websocket.possible? && allow_request_origin?
respond_to_successful_request
else
respond_to_invalid_request
end
end
# Decodes WebSocket messages and dispatches them to subscribed channels.
# WebSocket message transfer encoding is always JSON.
def receive(websocket_message) #:nodoc:
send_async :dispatch_websocket_message, websocket_message
end
def dispatch_websocket_message(websocket_message) #:nodoc:
if websocket.alive?
subscriptions.execute_command decode(websocket_message)
else
logger.error "Ignoring message processed after the WebSocket was closed: #{websocket_message.inspect})"
end
end
def transmit(cable_message) # :nodoc:
websocket.transmit encode(cable_message)
end
# Close the WebSocket connection.
def close(reason: nil, reconnect: true)
transmit(
type: ActionCable::INTERNAL[:message_types][:disconnect],
reason: reason,
reconnect: reconnect
)
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 <tt>identifier</tt>, <tt>started_at</tt>, <tt>subscriptions</tt>, and <tt>request_id</tt>.
# 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 type: ActionCable::INTERNAL[:message_types][:ping], message: Time.now.to_i
end
def on_open # :nodoc:
send_async :handle_open
end
def on_message(message) # :nodoc:
message_buffer.append message
end
def on_error(message) # :nodoc:
# log errors to make diagnosing socket errors easier
logger.error "WebSocket error occurred: #{message}"
end
def on_close(reason, code) # :nodoc:
send_async :handle_close
end
private
attr_reader :websocket
attr_reader :message_buffer
# The request that initiated the WebSocket connection is available here. This gives access to the environment, cookies, etc.
def request # :doc:
@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 # :doc:
request.cookie_jar
end
def encode(cable_message)
@coder.encode cable_message
end
def decode(websocket_message)
@coder.decode websocket_message
end
def handle_open
@protocol = websocket.protocol
connect if respond_to?(:connect)
subscribe_to_internal_channel
send_welcome_message
message_buffer.process!
server.add_connection(self)
rescue ActionCable::Connection::Authorization::UnauthorizedError
close(reason: ActionCable::INTERNAL[:disconnect_reasons][:unauthorized], reconnect: false) if websocket.alive?
end
def handle_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 send_welcome_message
# Send welcome message to the internal connection monitor channel.
# This ensures the connection monitor state is reset after a successful
# websocket connection.
transmit type: ActionCable::INTERNAL[:message_types][:welcome]
end
def allow_request_origin?
return true if server.config.disable_request_forgery_protection
proto = Rack::Request.new(env).ssl? ? "https" : "http"
if server.config.allow_same_origin_as_host && env["HTTP_ORIGIN"] == "#{proto}://#{env['HTTP_HOST']}"
true
elsif 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
logger.info successful_request_message
websocket.rack_response
end
def respond_to_invalid_request
close(reason: ActionCable::INTERNAL[:disconnect_reasons][:invalid_request]) if websocket.alive?
logger.error invalid_request_message
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]" : "[non-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]" : "[non-WebSocket]",
request.ip,
Time.now.to_s ]
end
def invalid_request_message
"Failed to upgrade to WebSocket (REQUEST_METHOD: %s, HTTP_CONNECTION: %s, HTTP_UPGRADE: %s)" % [
env["REQUEST_METHOD"], env["HTTP_CONNECTION"], env["HTTP_UPGRADE"]
]
end
def successful_request_message
"Successfully upgraded to WebSocket (REQUEST_METHOD: %s, HTTP_CONNECTION: %s, HTTP_UPGRADE: %s)" % [
env["REQUEST_METHOD"], env["HTTP_CONNECTION"], env["HTTP_UPGRADE"]
]
end
end
end
end
ActiveSupport.run_load_hooks(:action_cable_connection, ActionCable::Connection::Base)
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