Class: Rack::ShowExceptions

Inherits:
Object
  • Object
show all
Defined in:
lib/rack/show_exceptions.rb

Overview

Rack::ShowExceptions catches all exceptions raised from the app it wraps. It shows a useful backtrace with the sourcefile and clickable context, the whole Rack environment and the request data.

Be careful when you use this on public-facing sites as it could reveal information helpful to attackers.

Constant Summary collapse

CONTEXT = 
7
TEMPLATE =

adapted from Django <www.djangoproject.com> Copyright © Django Software Foundation and individual contributors. Used under the modified BSD license: www.xfree86.org/3.3.6/COPYRIGHT2.html#5

ERB.new("  <!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\" \"http://www.w3.org/TR/html4/loose.dtd\">\n  <html lang=\"en\">\n  <head>\n    <meta http-equiv=\"content-type\" content=\"text/html; charset=utf-8\" />\n    <meta name=\"robots\" content=\"NONE,NOARCHIVE\" />\n    <title><%=h exception.class %> at <%=h path %></title>\n    <style type=\"text/css\">\n      html * { padding:0; margin:0; }\n      body * { padding:10px 20px; }\n      body * * { padding:0; }\n      body { font:small sans-serif; }\n      body>div { border-bottom:1px solid #ddd; }\n      h1 { font-weight:normal; }\n      h2 { margin-bottom:.8em; }\n      h2 span { font-size:80%; color:#666; font-weight:normal; }\n      h3 { margin:1em 0 .5em 0; }\n      h4 { margin:0 0 .5em 0; font-weight: normal; }\n      table {\n          border:1px solid #ccc; border-collapse: collapse; background:white; }\n      tbody td, tbody th { vertical-align:top; padding:2px 3px; }\n      thead th {\n          padding:1px 6px 1px 3px; background:#fefefe; text-align:left;\n          font-weight:normal; font-size:11px; border:1px solid #ddd; }\n      tbody th { text-align:right; color:#666; padding-right:.5em; }\n      table.vars { margin:5px 0 2px 40px; }\n      table.vars td, table.req td { font-family:monospace; }\n      table td.code { width:100%;}\n      table td.code div { overflow:hidden; }\n      table.source th { color:#666; }\n      table.source td {\n          font-family:monospace; white-space:pre; border-bottom:1px solid #eee; }\n      ul.traceback { list-style-type:none; }\n      ul.traceback li.frame { margin-bottom:1em; }\n      div.context { margin: 10px 0; }\n      div.context ol {\n          padding-left:30px; margin:0 10px; list-style-position: inside; }\n      div.context ol li {\n          font-family:monospace; white-space:pre; color:#666; cursor:pointer; }\n      div.context ol.context-line li { color:black; background-color:#ccc; }\n      div.context ol.context-line li span { float: right; }\n      div.commands { margin-left: 40px; }\n      div.commands a { color:black; text-decoration:none; }\n      #summary { background: #ffc; }\n      #summary h2 { font-weight: normal; color: #666; }\n      #summary ul#quicklinks { list-style-type: none; margin-bottom: 2em; }\n      #summary ul#quicklinks li { float: left; padding: 0 1em; }\n      #summary ul#quicklinks>li+li { border-left: 1px #666 solid; }\n      #explanation { background:#eee; }\n      #template, #template-not-exist { background:#f6f6f6; }\n      #template-not-exist ul { margin: 0 0 0 20px; }\n      #traceback { background:#eee; }\n      #requestinfo { background:#f6f6f6; padding-left:120px; }\n      #summary table { border:none; background:transparent; }\n      #requestinfo h2, #requestinfo h3 { position:relative; margin-left:-100px; }\n      #requestinfo h3 { margin-bottom:-1em; }\n      .error { background: #ffc; }\n      .specific { color:#cc3300; font-weight:bold; }\n    </style>\n    <script type=\"text/javascript\">\n    //<!--\n      function getElementsByClassName(oElm, strTagName, strClassName){\n          // Written by Jonathan Snook, http://www.snook.ca/jon;\n          // Add-ons by Robert Nyman, http://www.robertnyman.com\n          var arrElements = (strTagName == \"*\" && document.all)? document.all :\n          oElm.getElementsByTagName(strTagName);\n          var arrReturnElements = new Array();\n          strClassName = strClassName.replace(/\\-/g, \"\\\\-\");\n          var oRegExp = new RegExp(\"(^|\\\\s)\" + strClassName + \"(\\\\s|$$)\");\n          var oElement;\n          for(var i=0; i<arrElements.length; i++){\n              oElement = arrElements[i];\n              if(oRegExp.test(oElement.className)){\n                  arrReturnElements.push(oElement);\n              }\n          }\n          return (arrReturnElements)\n      }\n      function hideAll(elems) {\n        for (var e = 0; e < elems.length; e++) {\n          elems[e].style.display = 'none';\n        }\n      }\n      window.onload = function() {\n        hideAll(getElementsByClassName(document, 'table', 'vars'));\n        hideAll(getElementsByClassName(document, 'ol', 'pre-context'));\n        hideAll(getElementsByClassName(document, 'ol', 'post-context'));\n      }\n      function toggle() {\n        for (var i = 0; i < arguments.length; i++) {\n          var e = document.getElementById(arguments[i]);\n          if (e) {\n            e.style.display = e.style.display == 'none' ? 'block' : 'none';\n          }\n        }\n        return false;\n      }\n      function varToggle(link, id) {\n        toggle('v' + id);\n        var s = link.getElementsByTagName('span')[0];\n        var uarr = String.fromCharCode(0x25b6);\n        var darr = String.fromCharCode(0x25bc);\n        s.innerHTML = s.innerHTML == uarr ? darr : uarr;\n        return false;\n      }\n      //-->\n    </script>\n  </head>\n  <body>\n\n  <div id=\"summary\">\n    <h1><%=h exception.class %> at <%=h path %></h1>\n    <h2><%=h exception.message %></h2>\n    <table><tr>\n      <th>Ruby</th>\n      <td>\n  <% if first = frames.first %>\n        <code><%=h first.filename %></code>: in <code><%=h first.function %></code>, line <%=h frames.first.lineno %>\n  <% else %>\n        unknown location\n  <% end %>\n      </td>\n    </tr><tr>\n      <th>Web</th>\n      <td><code><%=h req.request_method %> <%=h(req.host + path)%></code></td>\n    </tr></table>\n\n    <h3>Jump to:</h3>\n    <ul id=\"quicklinks\">\n      <li><a href=\"#get-info\">GET</a></li>\n      <li><a href=\"#post-info\">POST</a></li>\n      <li><a href=\"#cookie-info\">Cookies</a></li>\n      <li><a href=\"#env-info\">ENV</a></li>\n    </ul>\n  </div>\n\n  <div id=\"traceback\">\n    <h2>Traceback <span>(innermost first)</span></h2>\n    <ul class=\"traceback\">\n  <% frames.each { |frame| %>\n        <li class=\"frame\">\n          <code><%=h frame.filename %></code>: in <code><%=h frame.function %></code>\n\n            <% if frame.context_line %>\n            <div class=\"context\" id=\"c<%=h frame.object_id %>\">\n                <% if frame.pre_context %>\n                <ol start=\"<%=h frame.pre_context_lineno+1 %>\" class=\"pre-context\" id=\"pre<%=h frame.object_id %>\">\n                  <% frame.pre_context.each { |line| %>\n                  <li onclick=\"toggle('pre<%=h frame.object_id %>', 'post<%=h frame.object_id %>')\"><%=h line %></li>\n                  <% } %>\n                </ol>\n                <% end %>\n\n              <ol start=\"<%=h frame.lineno %>\" class=\"context-line\">\n                <li onclick=\"toggle('pre<%=h frame.object_id %>', 'post<%=h frame.object_id %>')\"><%=h frame.context_line %><span>...</span></li></ol>\n\n                <% if frame.post_context %>\n                <ol start='<%=h frame.lineno+1 %>' class=\"post-context\" id=\"post<%=h frame.object_id %>\">\n                  <% frame.post_context.each { |line| %>\n                  <li onclick=\"toggle('pre<%=h frame.object_id %>', 'post<%=h frame.object_id %>')\"><%=h line %></li>\n                  <% } %>\n                </ol>\n                <% end %>\n            </div>\n            <% end %>\n        </li>\n  <% } %>\n    </ul>\n  </div>\n\n  <div id=\"requestinfo\">\n    <h2>Request information</h2>\n\n    <h3 id=\"get-info\">GET</h3>\n    <% if req.GET and not req.GET.empty? %>\n      <table class=\"req\">\n        <thead>\n          <tr>\n            <th>Variable</th>\n            <th>Value</th>\n          </tr>\n        </thead>\n        <tbody>\n            <% req.GET.sort_by { |k, v| k.to_s }.each { |key, val| %>\n            <tr>\n              <td><%=h key %></td>\n              <td class=\"code\"><div><%=h val.inspect %></div></td>\n            </tr>\n            <% } %>\n        </tbody>\n      </table>\n    <% else %>\n      <p>No GET data.</p>\n    <% end %>\n\n    <h3 id=\"post-info\">POST</h3>\n    <% if ((req.POST and not req.POST.empty?) rescue (no_post_data = \"Invalid POST data\"; nil)) %>\n      <table class=\"req\">\n        <thead>\n          <tr>\n            <th>Variable</th>\n            <th>Value</th>\n          </tr>\n        </thead>\n        <tbody>\n            <% req.POST.sort_by { |k, v| k.to_s }.each { |key, val| %>\n            <tr>\n              <td><%=h key %></td>\n              <td class=\"code\"><div><%=h val.inspect %></div></td>\n            </tr>\n            <% } %>\n        </tbody>\n      </table>\n    <% else %>\n      <p><%= no_post_data || \"No POST data\" %>.</p>\n    <% end %>\n\n\n    <h3 id=\"cookie-info\">COOKIES</h3>\n    <% unless req.cookies.empty? %>\n      <table class=\"req\">\n        <thead>\n          <tr>\n            <th>Variable</th>\n            <th>Value</th>\n          </tr>\n        </thead>\n        <tbody>\n          <% req.cookies.each { |key, val| %>\n            <tr>\n              <td><%=h key %></td>\n              <td class=\"code\"><div><%=h val.inspect %></div></td>\n            </tr>\n          <% } %>\n        </tbody>\n      </table>\n    <% else %>\n      <p>No cookie data.</p>\n    <% end %>\n\n    <h3 id=\"env-info\">Rack ENV</h3>\n      <table class=\"req\">\n        <thead>\n          <tr>\n            <th>Variable</th>\n            <th>Value</th>\n          </tr>\n        </thead>\n        <tbody>\n            <% env.sort_by { |k, v| k.to_s }.each { |key, val| %>\n            <tr>\n              <td><%=h key %></td>\n              <td class=\"code\"><div><%=h val.inspect %></div></td>\n            </tr>\n            <% } %>\n        </tbody>\n      </table>\n\n  </div>\n\n  <div id=\"explanation\">\n    <p>\n      You're seeing this error because you use <code>Rack::ShowExceptions</code>.\n    </p>\n  </div>\n\n  </body>\n  </html>\n".gsub(/^      /, ''))

Instance Method Summary collapse

Constructor Details

#initialize(app) ⇒ ShowExceptions 



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# File 'lib/rack/show_exceptions.rb', line 18

def initialize(app)
  @app = app
end

Instance Method Details

#call(env) ⇒ Object 



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# File 'lib/rack/show_exceptions.rb', line 22

def call(env)
  @app.call(env)
rescue StandardError, LoadError, SyntaxError => e
  exception_string = dump_exception(e)

  env[RACK_ERRORS].puts(exception_string)
  env[RACK_ERRORS].flush

  if accepts_html?(env)
    content_type = "text/html"
    body = pretty(env, e)
  else
    content_type = "text/plain"
    body = exception_string
  end

  [
    500,
    {
      CONTENT_TYPE => content_type,
      CONTENT_LENGTH => body.bytesize.to_s,
    },
    [body],
  ]
end

#dump_exception(exception) ⇒ Object 



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# File 'lib/rack/show_exceptions.rb', line 57

def dump_exception(exception)
  string = "#{exception.class}: #{exception.message}\n".dup
  string << exception.backtrace.map { |l| "\t#{l}" }.join("\n")
  string
end

#h(obj) ⇒ Object

:nodoc:



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# File 'lib/rack/show_exceptions.rb', line 103

def h(obj)                  # :nodoc:
  case obj
  when String
    Utils.escape_html(obj)
  else
    Utils.escape_html(obj.inspect)
  end
end

#prefers_plaintext?(env) ⇒ Boolean 



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# File 'lib/rack/show_exceptions.rb', line 48

def prefers_plaintext?(env)
  !accepts_html?(env)
end

#pretty(env, exception) ⇒ Object 



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# File 'lib/rack/show_exceptions.rb', line 63

def pretty(env, exception)
  req = Rack::Request.new(env)

  # This double assignment is to prevent an "unused variable" warning.
  # Yes, it is dumb, but I don't like Ruby yelling at me.
  path = path = (req.script_name + req.path_info).squeeze("/")

  # This double assignment is to prevent an "unused variable" warning.
  # Yes, it is dumb, but I don't like Ruby yelling at me.
  frames = frames = exception.backtrace.map { |line|
    frame = OpenStruct.new
    if line =~ /(.*?):(\d+)(:in `(.*)')?/
      frame.filename = $1
      frame.lineno = $2.to_i
      frame.function = $4

      begin
        lineno = frame.lineno - 1
        lines = ::File.readlines(frame.filename)
        frame.pre_context_lineno = [lineno - CONTEXT, 0].max
        frame.pre_context = lines[frame.pre_context_lineno...lineno]
        frame.context_line = lines[lineno].chomp
        frame.post_context_lineno = [lineno + CONTEXT, lines.size].min
        frame.post_context = lines[lineno + 1..frame.post_context_lineno]
      rescue
      end

      frame
    else
      nil
    end
  }.compact

  template.result(binding)
end

#template ⇒ Object 



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# File 'lib/rack/show_exceptions.rb', line 99

def template
  TEMPLATE
end