aboutsummaryrefslogtreecommitdiffstats
path: root/actionpack/lib/action_dispatch/middleware/show_exceptions.rb
blob: ef0c9c51f5fab33ced26d3687dc44ae0df064b3a (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
require 'active_support/core_ext/exception'
require 'active_support/notifications'
require 'action_dispatch/http/request'

module ActionDispatch
  # This middleware rescues any exception returned by the application and renders
  # nice exception pages if it's being rescued locally.
  class ShowExceptions
    RESCUES_TEMPLATE_PATH = File.join(File.dirname(__FILE__), 'templates')

    cattr_accessor :rescue_responses
    @@rescue_responses = Hash.new(:internal_server_error)
    @@rescue_responses.update({
      'ActionController::RoutingError'             => :not_found,
      'AbstractController::ActionNotFound'         => :not_found,
      'ActiveRecord::RecordNotFound'               => :not_found,
      'ActiveRecord::StaleObjectError'             => :conflict,
      'ActiveRecord::RecordInvalid'                => :unprocessable_entity,
      'ActiveRecord::RecordNotSaved'               => :unprocessable_entity,
      'ActionController::MethodNotAllowed'         => :method_not_allowed,
      'ActionController::NotImplemented'           => :not_implemented,
      'ActionController::InvalidAuthenticityToken' => :unprocessable_entity
    })

    cattr_accessor :rescue_templates
    @@rescue_templates = Hash.new('diagnostics')
    @@rescue_templates.update({
      'ActionView::MissingTemplate'         => 'missing_template',
      'ActionController::RoutingError'      => 'routing_error',
      'AbstractController::ActionNotFound'  => 'unknown_action',
      'ActionView::Template::Error'         => 'template_error'
    })

    FAILSAFE_RESPONSE = [500, {'Content-Type' => 'text/html'},
      ["<html><body><h1>500 Internal Server Error</h1>" <<
       "If you are the administrator of this website, then please read this web " <<
       "application's log file and/or the web server's log file to find out what " <<
       "went wrong.</body></html>"]]

    def initialize(app, consider_all_requests_local = false)
      @app = app
      @consider_all_requests_local = consider_all_requests_local
    end

    def call(env)
      status, headers, body = @app.call(env)

      # Only this middleware cares about RoutingError. So, let's just raise
      # it here.
      # TODO: refactor this middleware to handle the X-Cascade scenario without
      # having to raise an exception.
      if headers['X-Cascade'] == 'pass'
        raise ActionController::RoutingError, "No route matches #{env['PATH_INFO'].inspect}"
      end

      [status, headers, body]
    rescue Exception => exception
      raise exception if env['action_dispatch.show_exceptions'] == false
      render_exception(env, exception)
    end

    private
      def render_exception(env, exception)
        log_error(exception)

        request = Request.new(env)
        if @consider_all_requests_local || request.local?
          rescue_action_locally(request, exception)
        else
          rescue_action_in_public(exception)
        end
      rescue Exception => failsafe_error
        $stderr.puts "Error during failsafe response: #{failsafe_error}\n  #{failsafe_error.backtrace * "\n  "}"
        FAILSAFE_RESPONSE
      end

      # Render detailed diagnostics for unhandled exceptions rescued from
      # a controller action.
      def rescue_action_locally(request, exception)
        template = ActionView::Base.new([RESCUES_TEMPLATE_PATH],
          :request => request,
          :exception => exception,
          :application_trace => application_trace(exception),
          :framework_trace => framework_trace(exception),
          :full_trace => full_trace(exception)
        )
        file = "rescues/#{@@rescue_templates[exception.class.name]}.erb"
        body = template.render(:file => file, :layout => 'rescues/layout.erb')
        render(status_code(exception), body)
      end

      # Attempts to render a static error page based on the
      # <tt>status_code</tt> thrown, or just return headers if no such file
      # exists. At first, it will try to render a localized static page.
      # For example, if a 500 error is being handled Rails and locale is :da,
      # it will first attempt to render the file at <tt>public/500.da.html</tt>
      # then attempt to render <tt>public/500.html</tt>. If none of them exist,
      # the body of the response will be left empty.
      def rescue_action_in_public(exception)
        status = status_code(exception)
        locale_path = "#{public_path}/#{status}.#{I18n.locale}.html" if I18n.locale
        path = "#{public_path}/#{status}.html"

        if locale_path && File.exist?(locale_path)
          render(status, File.read(locale_path))
        elsif File.exist?(path)
          render(status, File.read(path))
        else
          render(status, '')
        end
      end

      def status_code(exception)
        Rack::Utils.status_code(@@rescue_responses[exception.class.name])
      end

      def render(status, body)
        [status, {'Content-Type' => 'text/html', 'Content-Length' => body.bytesize.to_s}, [body]]
      end

      def public_path
        defined?(Rails.public_path) ? Rails.public_path : 'public_path'
      end

      def log_error(exception)
        return unless logger

        ActiveSupport::Deprecation.silence do
          message = "\n#{exception.class} (#{exception.message}):\n"
          message << exception.annoted_source_code.to_s if exception.respond_to?(:annoted_source_code)
          message << "  " << application_trace(exception).join("\n  ")
          logger.fatal("#{message}\n\n")
        end
      end

      def application_trace(exception)
        clean_backtrace(exception, :silent)
      end

      def framework_trace(exception)
        clean_backtrace(exception, :noise)
      end

      def full_trace(exception)
        clean_backtrace(exception, :all)
      end

      def clean_backtrace(exception, *args)
        defined?(Rails) && Rails.respond_to?(:backtrace_cleaner) ?
          Rails.backtrace_cleaner.clean(exception.backtrace, *args) :
          exception.backtrace
      end

      def logger
        defined?(Rails.logger) ? Rails.logger : Logger.new($stderr)
      end
  end
end