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This middleware guards from DNS rebinding attacks by explicitly permitting the hosts a request can be sent to, and is passed the options set in config.host_authorization.

Requests can opt-out of Host Authorization with exclude:

config.host_authorization = { exclude: ->(request) { request.path =~ /healthcheck/ } }

When a request comes to an unauthorized host, the response_app application will be executed and rendered. If no response_app is given, a default one will run, which responds with 403 Forbidden.

Methods
C
N

Constants

DEFAULT_RESPONSE_APP = -> env do request = Request.new(env) format = request.xhr? ? "text/plain" : "text/html" template = DebugView.new(host: request.host) body = template.render(template: "rescues/blocked_host", layout: "rescues/layout") [403, { "Content-Type" => "#{format}; charset=#{Response.default_charset}", "Content-Length" => body.bytesize.to_s, }, [body]] end
 

Class Public methods

new(app, hosts, deprecated_response_app = nil, exclude: nil, response_app: nil)

Source: show | on GitHub 

# File actionpack/lib/action_dispatch/middleware/host_authorization.rb, line 74
    def initialize(app, hosts, deprecated_response_app = nil, exclude: nil, response_app: nil)
      @app = app
      @permissions = Permissions.new(hosts)
      @exclude = exclude

      unless deprecated_response_app.nil?
        ActiveSupport::Deprecation.warn(<<-MSG.squish)
          `action_dispatch.hosts_response_app` is deprecated and will be ignored in Rails 6.2.
          Use the Host Authorization `response_app` setting instead.
        MSG

        response_app ||= deprecated_response_app
      end

      @response_app = response_app || DEFAULT_RESPONSE_APP
    end

Instance Public methods

call(env)

Source: show | on GitHub 

# File actionpack/lib/action_dispatch/middleware/host_authorization.rb, line 91
def call(env)
  return @app.call(env) if @permissions.empty?

  request = Request.new(env)

  if authorized?(request) || excluded?(request)
    mark_as_authorized(request)
    @app.call(env)
  else
    @response_app.call(env)
  end
end