Class: Middleware::RequestTracker

Inherits:
Object
  • Object
show all
Defined in:
lib/middleware/request_tracker.rb

Constant Summary collapse

STATIC_IP_SKIPPER =

You can add exceptions to our app rate limiter in the app.yml ENV section. example:

env:

DISCOURSE_MAX_REQS_PER_IP_EXCEPTIONS: >-
  14.15.16.32/27
  216.148.1.2
ENV["DISCOURSE_MAX_REQS_PER_IP_EXCEPTIONS"]&.split&.map { |ip| IPAddr.new(ip) }
@@detailed_request_loggers =
nil
@@ip_skipper =
nil

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(app, settings = {}) ⇒ RequestTracker

Returns a new instance of RequestTracker.



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# File 'lib/middleware/request_tracker.rb', line 81

def initialize(app, settings = {})
  @app = app
end

Class Method Details

.get_data(env, result, timing, request = nil) ⇒ Object



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# File 'lib/middleware/request_tracker.rb', line 167

def self.get_data(env, result, timing, request = nil)
  status, headers = result

  # result may be nil if the downstream app raised an exception
  status = status.to_i
  headers ||= {}

  request ||= Rack::Request.new(env)
  helper = Middleware::AnonymousCache::Helper.new(env, request)

  # Since ActionDispatch::RemoteIp middleware is run before this middleware,
  # we have access to the normalised remote IP based on ActionDispatch::RemoteIp::GetIp
  #
  # NOTE: Locally with MessageBus requests, the remote IP ends up as ::1 because
  # of the X-Forwarded-For header set...somewhere, whereas all other requests
  # end up as 127.0.0.1.
  request_remote_ip = env["action_dispatch.remote_ip"].to_s

  # Value of the discourse-track-view request header, set in `lib/ajax.js`
  env_track_view = env["HTTP_DISCOURSE_TRACK_VIEW"]

  # Was the discourse-track-view request header set to true? Likely
  # set by our ajax library to indicate a page view.
  explicit_track_view = status == 200 && %w[1 true].include?(env_track_view)

  # An HTML response to a GET request is tracked implicitly
  implicit_track_view =
    status == 200 && !%w[0 false].include?(env_track_view) && request.get? && !request.xhr? &&
      headers["Content-Type"] =~ %r{text/html}

  # This header is sent on a follow-up request after a real browser loads up a page
  # see `scripts/pageview.js` and `instance-initializers/page-tracking.js`
  deferred_track_view = %w[1 true].include?(env["HTTP_DISCOURSE_DEFERRED_TRACK_VIEW"])

  # This is treated separately from deferred tracking in #log_request, this is
  # why deferred_track_view is not counted here.
  track_view = !!(explicit_track_view || implicit_track_view)

  # These are set in the same place as the respective track view headers in the client.
  topic_id =
    if deferred_track_view
      env["HTTP_DISCOURSE_DEFERRED_TRACK_VIEW_TOPIC_ID"]
    elsif explicit_track_view || implicit_track_view
      env["HTTP_DISCOURSE_TRACK_VIEW_TOPIC_ID"]
    end

  auth_cookie = Auth::DefaultCurrentUserProvider.find_v0_auth_cookie(request)
  auth_cookie ||= Auth::DefaultCurrentUserProvider.find_v1_auth_cookie(env)
  has_auth_cookie = auth_cookie.present?

  is_api ||= !!env[Auth::DefaultCurrentUserProvider::API_KEY_ENV]
  is_user_api ||= !!env[Auth::DefaultCurrentUserProvider::USER_API_KEY_ENV]

  is_message_bus = request.path.start_with?("#{Discourse.base_path}/message-bus/")
  is_topic_timings = request.path.start_with?("#{Discourse.base_path}/topics/timings")

  # Auth cookie can be used to find the ID for logged in users, but API calls must look up the
  # current user based on env variables.
  #
  # We only care about this for topic views, other pageviews it's enough to know if the user is
  # logged in or not, and we have separate pageview tracking for API views.
  current_user_id =
    if topic_id.present?
      begin
        (auth_cookie&.[](:user_id) || CurrentUser.lookup_from_env(env)&.id)
      rescue Discourse::InvalidAccess => err
        # This error is raised when the API key is invalid, no need to stop the show.
        Discourse.warn_exception(
          err,
          message: "RequestTracker.get_data failed with an invalid API key error",
        )
        nil
      end
    end

  h = {
    status: status,
    is_crawler: helper.is_crawler?,
    has_auth_cookie: has_auth_cookie,
    current_user_id: current_user_id,
    topic_id: topic_id,
    is_api: is_api,
    is_user_api: is_user_api,
    is_background: is_message_bus || is_topic_timings,
    is_mobile: helper.is_mobile?,
    track_view: track_view,
    timing: timing,
    queue_seconds: env["REQUEST_QUEUE_SECONDS"],
    explicit_track_view: explicit_track_view,
    deferred_track: deferred_track_view,
    request_remote_ip: request_remote_ip,
  }

  if h[:is_background]
    h[:background_type] = if is_message_bus
      if request.query_string.include?("dlp=t")
        "message-bus-dlp"
      elsif env["HTTP_DONT_CHUNK"]
        "message-bus-dontchunk"
      else
        "message-bus"
      end
    else
      "topic-timings"
    end
  end

  if h[:is_crawler]
    user_agent = env["HTTP_USER_AGENT"]
    user_agent = HttpUserAgentEncoder.ensure_utf8(user_agent) if user_agent
    h[:user_agent] = user_agent
  end

  if cache = headers["X-Discourse-Cached"]
    h[:cache] = cache
  end

  h
end

.ip_skipperObject



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# File 'lib/middleware/request_tracker.rb', line 58

def self.ip_skipper
  @@ip_skipper
end

.log_request(data) ⇒ Object



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# File 'lib/middleware/request_tracker.rb', line 85

def self.log_request(data)
  if data[:is_api]
    ApplicationRequest.increment!(:api)
  elsif data[:is_user_api]
    ApplicationRequest.increment!(:user_api)
  elsif data[:track_view]
    if data[:is_crawler]
      ApplicationRequest.increment!(:page_view_crawler)
      WebCrawlerRequest.increment!(data[:user_agent])
    elsif data[:has_auth_cookie]
      ApplicationRequest.increment!(:page_view_logged_in)
      ApplicationRequest.increment!(:page_view_logged_in_mobile) if data[:is_mobile]

      if data[:explicit_track_view]
        # Must be a browser if it had this header from our ajax implementation
        ApplicationRequest.increment!(:page_view_logged_in_browser)
        ApplicationRequest.increment!(:page_view_logged_in_browser_mobile) if data[:is_mobile]

        if data[:topic_id].present? && data[:current_user_id].present?
          TopicsController.defer_topic_view(
            data[:topic_id],
            data[:request_remote_ip],
            data[:current_user_id],
          )
        end
      end
    elsif !SiteSetting.
      ApplicationRequest.increment!(:page_view_anon)
      ApplicationRequest.increment!(:page_view_anon_mobile) if data[:is_mobile]

      if data[:explicit_track_view]
        # Must be a browser if it had this header from our ajax implementation
        ApplicationRequest.increment!(:page_view_anon_browser)
        ApplicationRequest.increment!(:page_view_anon_browser_mobile) if data[:is_mobile]

        if data[:topic_id].present?
          TopicsController.defer_topic_view(data[:topic_id], data[:request_remote_ip])
        end
      end
    end
  end

  # Message-bus requests may include this 'deferred track' header which we use to detect
  # 'real browser' views.
  if data[:deferred_track] && !data[:is_crawler]
    if data[:has_auth_cookie]
      ApplicationRequest.increment!(:page_view_logged_in_browser)
      ApplicationRequest.increment!(:page_view_logged_in_browser_mobile) if data[:is_mobile]

      if data[:topic_id].present? && data[:current_user_id].present?
        TopicsController.defer_topic_view(
          data[:topic_id],
          data[:request_remote_ip],
          data[:current_user_id],
        )
      end
    elsif !SiteSetting.
      ApplicationRequest.increment!(:page_view_anon_browser)
      ApplicationRequest.increment!(:page_view_anon_browser_mobile) if data[:is_mobile]

      if data[:topic_id].present?
        TopicsController.defer_topic_view(data[:topic_id], data[:request_remote_ip])
      end
    end
  end

  ApplicationRequest.increment!(:http_total)

  status = data[:status]
  if status >= 500
    ApplicationRequest.increment!(:http_5xx)
  elsif data[:is_background]
    ApplicationRequest.increment!(:http_background)
  elsif status >= 400
    ApplicationRequest.increment!(:http_4xx)
  elsif status >= 300
    ApplicationRequest.increment!(:http_3xx)
  elsif status >= 200
    ApplicationRequest.increment!(:http_2xx)
  end
end

.populate_request_queue_seconds!(env) ⇒ Object



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# File 'lib/middleware/request_tracker.rb', line 314

def self.populate_request_queue_seconds!(env)
  if !env["REQUEST_QUEUE_SECONDS"]
    if queue_start = env["HTTP_X_REQUEST_START"]
      queue_start =
        if queue_start.start_with?("t=")
          queue_start.split("t=")[1].to_f
        else
          queue_start.to_f / 1000.0
        end
      queue_time = (Time.now.to_f - queue_start)
      env["REQUEST_QUEUE_SECONDS"] = queue_time
    end
  end
end

.rate_limiters_stackObject



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# File 'lib/middleware/request_tracker.rb', line 77

def self.rate_limiters_stack
  @@stack ||= reset_rate_limiters_stack
end

.register_detailed_request_logger(callback) ⇒ Object

register callbacks for detailed request loggers called on every request example:

Middleware::RequestTracker.detailed_request_logger(->|env, data| do

# do stuff with env and data

end



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# File 'lib/middleware/request_tracker.rb', line 28

def self.register_detailed_request_logger(callback)
  MethodProfiler.ensure_discourse_instrumentation!
  (@@detailed_request_loggers ||= []) << callback
end

.register_ip_skipper(&blk) ⇒ Object

Register a custom ‘ip_skipper`, a function that will skip rate limiting for any IP that returns true.

For example, if you never wanted to rate limit 1.2.3.4

“‘ Middleware::RequestTracker.register_ip_skipper do |ip|

ip == "1.2.3.4"

end “‘



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# File 'lib/middleware/request_tracker.rb', line 53

def self.register_ip_skipper(&blk)
  raise "IP skipper is already registered!" if @@ip_skipper
  @@ip_skipper = blk
end

.reset_rate_limiters_stackObject



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# File 'lib/middleware/request_tracker.rb', line 62

def self.reset_rate_limiters_stack
  @@stack =
    begin
      # Update the documentation for the `add_request_rate_limiter` plugin API if this list changes.
      default_rate_limiters = [
        RequestTracker::RateLimiters::User,
        RequestTracker::RateLimiters::IP,
      ]

      stack = RequestTracker::RateLimiters::Stack.new
      default_rate_limiters.each { |limiter| stack.append(limiter) }
      stack
    end
end

.unregister_detailed_request_logger(callback) ⇒ Object



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# File 'lib/middleware/request_tracker.rb', line 33

def self.unregister_detailed_request_logger(callback)
  @@detailed_request_loggers.delete(callback)
  @detailed_request_loggers = nil if @@detailed_request_loggers.length == 0
end

.unregister_ip_skipperObject

used for testing



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# File 'lib/middleware/request_tracker.rb', line 39

def self.unregister_ip_skipper
  @@ip_skipper = nil
end

Instance Method Details

#call(env) ⇒ Object



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# File 'lib/middleware/request_tracker.rb', line 329

def call(env)
  result = nil
  info = nil
  gc_stat_timing = nil

  # doing this as early as possible so we have an
  # accurate counter
  ::Middleware::RequestTracker.populate_request_queue_seconds!(env)

  request = Rack::Request.new(env)
  cookie = find_auth_cookie(env)

  if error_details = rate_limit(request, cookie)
    available_in, error_code = error_details

    message = <<~TEXT
      Slow down, you're making too many requests.
      Please retry again in #{available_in} seconds.
      Error code: #{error_code}.
    TEXT

    headers = {
      "Content-Type" => "text/plain",
      "Retry-After" => available_in.to_s,
      "Discourse-Rate-Limit-Error-Code" => error_code,
    }

    if username = cookie&.[](:username)
      headers["X-Discourse-Username"] = username
    end

    return 429, headers, [message]
  end

  if !cookie
    if error_details = check_crawler_limits(env)
      available_in, error_code = error_details
      message = "Too many crawling requests. Error code: #{error_code}."

      headers = {
        "Content-Type" => "text/plain",
        "Retry-After" => available_in.to_s,
        "Discourse-Rate-Limit-Error-Code" => error_code,
      }

      return 429, headers, [message]
    end
  end

  env["discourse.request_tracker"] = self

  MethodProfiler.start

  if SiteSetting.instrument_gc_stat_per_request
    gc_stat_timing = GCStatInstrumenter.instrument { result = @app.call(env) }
  else
    result = @app.call(env)
  end

  info = MethodProfiler.stop

  # possibly transferred?
  if info && (headers = result[1])
    headers["X-Runtime"] = "%0.6f" % info[:total_duration]

    if GlobalSetting.enable_performance_http_headers
      if redis = info[:redis]
        headers["X-Redis-Calls"] = redis[:calls].to_s
        headers["X-Redis-Time"] = "%0.6f" % redis[:duration]
      end

      if sql = info[:sql]
        headers["X-Sql-Calls"] = sql[:calls].to_s
        headers["X-Sql-Time"] = "%0.6f" % sql[:duration]
      end

      if queue = env["REQUEST_QUEUE_SECONDS"]
        headers["X-Queue-Time"] = "%0.6f" % queue
      end
    end
  end

  if env[Auth::DefaultCurrentUserProvider::BAD_TOKEN] && (headers = result[1])
    headers["Discourse-Logged-Out"] = "1"
  end

  result
ensure
  if (limiters = env["DISCOURSE_RATE_LIMITERS"]) && env["DISCOURSE_IS_ASSET_PATH"]
    limiters.each(&:rollback!)

    env["DISCOURSE_ASSET_RATE_LIMITERS"].each do |limiter|
      begin
        limiter.performed!
      rescue RateLimiter::LimitExceeded
        # skip
      end
    end
  end

  if !env["discourse.request_tracker.skip"]
    info.merge!(gc_stat_timing) if gc_stat_timing
    log_request_info(env, result, info, request)
  end
end

#check_crawler_limits(env) ⇒ Object



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# File 'lib/middleware/request_tracker.rb', line 554

def check_crawler_limits(env)
  slow_down_agents = SiteSetting.slow_down_crawler_user_agents
  return if slow_down_agents.blank?

  user_agent = HttpUserAgentEncoder.ensure_utf8(env["HTTP_USER_AGENT"])&.downcase
  return if user_agent.blank?

  return if !CrawlerDetection.crawler?(user_agent)

  slow_down_agents
    .downcase
    .split("|")
    .each do |crawler|
      if user_agent.include?(crawler)
        key = "#{crawler}_crawler_rate_limit"
        limiter =
          RateLimiter.new(nil, key, 1, SiteSetting.slow_down_crawler_rate, error_code: key)
        limiter.performed!
        break
      end
    end
  nil
rescue RateLimiter::LimitExceeded => e
  [e.available_in, e.error_code]
end


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# File 'lib/middleware/request_tracker.rb', line 445

def find_auth_cookie(env)
  min_allowed_timestamp = Time.now.to_i - (UserAuthToken::ROTATE_TIME_MINS + 1) * 60
  cookie = Auth::DefaultCurrentUserProvider.find_v1_auth_cookie(env)
  cookie if cookie && cookie[:issued_at] >= min_allowed_timestamp
end

#is_private_ip?(ip) ⇒ Boolean

Returns:

  • (Boolean)


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# File 'lib/middleware/request_tracker.rb', line 451

def is_private_ip?(ip)
  ip = IPAddr.new(ip)
  !!(ip && (ip.private? || ip.loopback?))
rescue IPAddr::AddressFamilyError, IPAddr::InvalidAddressError
  false
end

#log_later(data) ⇒ Object



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# File 'lib/middleware/request_tracker.rb', line 435

def log_later(data)
  Scheduler::Defer.later("Track view") do
    begin
      self.class.log_request(data) unless Discourse.pg_readonly_mode?
    rescue ActiveRecord::ReadOnlyError
      # Just noop if ActiveRecord is preventing writes
    end
  end
end

#log_request_info(env, result, info, request = nil) ⇒ Object



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# File 'lib/middleware/request_tracker.rb', line 287

def log_request_info(env, result, info, request = nil)
  # We've got to skip this on error ... its just logging
  data =
    begin
      self.class.get_data(env, result, info, request)
    rescue StandardError => err
      Discourse.warn_exception(err, message: "RequestTracker.get_data failed")

      # This is super hard to find if in testing, we should still raise in this case.
      raise err if Rails.env.test?

      nil
    end

  if data
    if result && (headers = result[1])
      headers["X-Discourse-TrackView"] = "1" if data[:track_view]
    end

    if @@detailed_request_loggers
      @@detailed_request_loggers.each { |logger| logger.call(env, data) }
    end

    log_later(data)
  end
end

#rate_limit(request, cookie) ⇒ Object



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# File 'lib/middleware/request_tracker.rb', line 458

def rate_limit(request, cookie)
  warn =
    GlobalSetting.max_reqs_per_ip_mode == "warn" ||
      GlobalSetting.max_reqs_per_ip_mode == "warn+block"

  block =
    GlobalSetting.max_reqs_per_ip_mode == "block" ||
      GlobalSetting.max_reqs_per_ip_mode == "warn+block"

  return if !block && !warn

  ip = request.ip

  if !GlobalSetting.max_reqs_rate_limit_on_private
    return if is_private_ip?(ip)
  end

  return if @@ip_skipper&.call(ip)
  return if STATIC_IP_SKIPPER&.any? { |entry| entry.include?(ip) }

  rate_limiter = self.class.rate_limiters_stack.active_rate_limiter(request, cookie)
  return nil if rate_limiter.nil?
  rate_limit_key = rate_limiter.rate_limit_key
  error_code_identifier = rate_limiter.error_code_identifier
  global = rate_limiter.rate_limit_globally?

  limiter10 =
    RateLimiter.new(
      nil,
      "global_limit_10_#{rate_limit_key}",
      GlobalSetting.max_reqs_per_ip_per_10_seconds,
      10,
      global:,
      aggressive: true,
      error_code: "#{error_code_identifier}_10_secs_limit",
    )

  limiter60 =
    RateLimiter.new(
      nil,
      "global_limit_60_#{rate_limit_key}",
      GlobalSetting.max_reqs_per_ip_per_minute,
      60,
      global:,
      error_code: "#{error_code_identifier}_60_secs_limit",
      aggressive: true,
    )

  limiter_assets10 =
    RateLimiter.new(
      nil,
      "global_limit_10_assets_#{rate_limit_key}",
      GlobalSetting.max_asset_reqs_per_ip_per_10_seconds,
      10,
      error_code: "#{error_code_identifier}_assets_10_secs_limit",
      global:,
    )

  request.env["DISCOURSE_RATE_LIMITERS"] = [limiter10, limiter60]
  request.env["DISCOURSE_ASSET_RATE_LIMITERS"] = [limiter_assets10]

  if !limiter_assets10.can_perform?
    if warn
      Discourse.warn(
        "Global asset rate limit exceeded for #{rate_limiter.class.name}: #{rate_limit_key}: 10 second rate limit",
        uri: request.env["REQUEST_URI"],
      )
    end

    return limiter_assets10.seconds_to_wait(Time.now.to_i), limiter_assets10.error_code if block
  end

  begin
    type = 10
    limiter10.performed!

    type = 60
    limiter60.performed!

    nil
  rescue RateLimiter::LimitExceeded => e
    if warn
      Discourse.warn(
        "Global rate limit exceeded for #{rate_limiter.class.name}: #{rate_limit_key}: #{type} second rate limit",
        uri: request.env["REQUEST_URI"],
      )
    end

    if block
      [e.available_in, e.error_code]
    else
      nil
    end
  end
end