Class: Rack::ShowExceptions

Inherits:
Object
  • Object
show all
Defined in:
lib/rack/showexceptions.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 <djangoproject.com> Copyright © 2005, the Lawrence Journal-World Used under the modified BSD license: www.xfree86.org/3.3.6/COPYRIGHT2.html#5

<<'HTML'
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html lang="en">
<head>
  <meta http-equiv="content-type" content="text/html; charset=utf-8" />
  <meta name="robots" content="NONE,NOARCHIVE" />
  <title><%=h exception.class %> at <%=h path %></title>
  <style type="text/css">
    html * { padding:0; margin:0; }
    body * { padding:10px 20px; }
    body * * { padding:0; }
    body { font:small sans-serif; }
    body>div { border-bottom:1px solid #ddd; }
    h1 { font-weight:normal; }
    h2 { margin-bottom:.8em; }
    h2 span { font-size:80%; color:#666; font-weight:normal; }
    h3 { margin:1em 0 .5em 0; }
    h4 { margin:0 0 .5em 0; font-weight: normal; }
    table {
        border:1px solid #ccc; border-collapse: collapse; background:white; }
    tbody td, tbody th { vertical-align:top; padding:2px 3px; }
    thead th {
        padding:1px 6px 1px 3px; background:#fefefe; text-align:left;
        font-weight:normal; font-size:11px; border:1px solid #ddd; }
    tbody th { text-align:right; color:#666; padding-right:.5em; }
    table.vars { margin:5px 0 2px 40px; }
    table.vars td, table.req td { font-family:monospace; }
    table td.code { width:100%;}
    table td.code div { overflow:hidden; }
    table.source th { color:#666; }
    table.source td {
        font-family:monospace; white-space:pre; border-bottom:1px solid #eee; }
    ul.traceback { list-style-type:none; }
    ul.traceback li.frame { margin-bottom:1em; }
    div.context { margin: 10px 0; }
    div.context ol {
        padding-left:30px; margin:0 10px; list-style-position: inside; }
    div.context ol li {
        font-family:monospace; white-space:pre; color:#666; cursor:pointer; }
    div.context ol.context-line li { color:black; background-color:#ccc; }
    div.context ol.context-line li span { float: right; }
    div.commands { margin-left: 40px; }
    div.commands a { color:black; text-decoration:none; }
    #summary { background: #ffc; }
    #summary h2 { font-weight: normal; color: #666; }
    #summary ul#quicklinks { list-style-type: none; margin-bottom: 2em; }
    #summary ul#quicklinks li { float: left; padding: 0 1em; }
    #summary ul#quicklinks>li+li { border-left: 1px #666 solid; }
    #explanation { background:#eee; }
    #template, #template-not-exist { background:#f6f6f6; }
    #template-not-exist ul { margin: 0 0 0 20px; }
    #traceback { background:#eee; }
    #requestinfo { background:#f6f6f6; padding-left:120px; }
    #summary table { border:none; background:transparent; }
    #requestinfo h2, #requestinfo h3 { position:relative; margin-left:-100px; }
    #requestinfo h3 { margin-bottom:-1em; }
    .error { background: #ffc; }
    .specific { color:#cc3300; font-weight:bold; }
  </style>
  <script type="text/javascript">
  //<!--
    function getElementsByClassName(oElm, strTagName, strClassName){
        // Written by Jonathan Snook, http://www.snook.ca/jon;
        // Add-ons by Robert Nyman, http://www.robertnyman.com
        var arrElements = (strTagName == "*" && document.all)? document.all :
        oElm.getElementsByTagName(strTagName);
        var arrReturnElements = new Array();
        strClassName = strClassName.replace(/\-/g, "\\-");
        var oRegExp = new RegExp("(^|\\s)" + strClassName + "(\\s|$$)");
        var oElement;
        for(var i=0; i<arrElements.length; i++){
            oElement = arrElements[i];
            if(oRegExp.test(oElement.className)){
                arrReturnElements.push(oElement);
            }
        }
        return (arrReturnElements)
    }
    function hideAll(elems) {
      for (var e = 0; e < elems.length; e++) {
        elems[e].style.display = 'none';
      }
    }
    window.onload = function() {
      hideAll(getElementsByClassName(document, 'table', 'vars'));
      hideAll(getElementsByClassName(document, 'ol', 'pre-context'));
      hideAll(getElementsByClassName(document, 'ol', 'post-context'));
    }
    function toggle() {
      for (var i = 0; i < arguments.length; i++) {
        var e = document.getElementById(arguments[i]);
        if (e) {
          e.style.display = e.style.display == 'none' ? 'block' : 'none';
        }
      }
      return false;
    }
    function varToggle(link, id) {
      toggle('v' + id);
      var s = link.getElementsByTagName('span')[0];
      var uarr = String.fromCharCode(0x25b6);
      var darr = String.fromCharCode(0x25bc);
      s.innerHTML = s.innerHTML == uarr ? darr : uarr;
      return false;
    }
    //-->
  </script>
</head>
<body>

<div id="summary">
  <h1><%=h exception.class %> at <%=h path %></h1>
  <h2><%=h exception.message %></h2>
  <table><tr>
    <th>Ruby</th>
    <td><code><%=h frames.first.filename %></code>: in <code><%=h frames.first.function %></code>, line <%=h frames.first.lineno %></td>
  </tr><tr>
    <th>Web</th>
    <td><code><%=h req.request_method %> <%=h(req.host + path)%></code></td>
  </tr></table>

  <h3>Jump to:</h3>
  <ul id="quicklinks">
    <li><a href="#get-info">GET</a></li>
    <li><a href="#post-info">POST</a></li>
    <li><a href="#cookie-info">Cookies</a></li>
    <li><a href="#env-info">ENV</a></li>
  </ul>
</div>

<div id="traceback">
  <h2>Traceback <span>(innermost first)</span></h2>
  <ul class="traceback">
<% frames.each { |frame| %>
      <li class="frame">
        <code><%=h frame.filename %></code>: in <code><%=h frame.function %></code>

          <% if frame.context_line %>
          <div class="context" id="c<%=h frame.object_id %>">
              <% if frame.pre_context %>
              <ol start="<%=h frame.pre_context_lineno+1 %>" class="pre-context" id="pre<%=h frame.object_id %>">
                <% frame.pre_context.each { |line| %>
                <li onclick="toggle('pre<%=h frame.object_id %>', 'post<%=h frame.object_id %>')"><%=h line %></li>
                <% } %>
              </ol>
              <% end %>

            <ol start="<%=h frame.lineno %>" class="context-line">
              <li onclick="toggle('pre<%=h frame.object_id %>', 'post<%=h frame.object_id %>')"><%=h frame.context_line %><span>...</span></li></ol>

              <% if frame.post_context %>
              <ol start='<%=h frame.lineno+1 %>' class="post-context" id="post<%=h frame.object_id %>">
                <% frame.post_context.each { |line| %>
                <li onclick="toggle('pre<%=h frame.object_id %>', 'post<%=h frame.object_id %>')"><%=h line %></li>
                <% } %>
              </ol>
              <% end %>
          </div>
          <% end %>
      </li>
<% } %>
  </ul>
</div>

<div id="requestinfo">
  <h2>Request information</h2>

  <h3 id="get-info">GET</h3>
  <% unless req.GET.empty? %>
    <table class="req">
      <thead>
        <tr>
          <th>Variable</th>
          <th>Value</th>
        </tr>
      </thead>
      <tbody>
          <% req.GET.sort_by { |k, v| k.to_s }.each { |key, val| %>
          <tr>
            <td><%=h key %></td>
            <td class="code"><div><%=h val.inspect %></div></td>
          </tr>
          <% } %>
      </tbody>
    </table>
  <% else %>
    <p>No GET data.</p>
  <% end %>

  <h3 id="post-info">POST</h3>
  <% unless req.POST.empty? %>
    <table class="req">
      <thead>
        <tr>
          <th>Variable</th>
          <th>Value</th>
        </tr>
      </thead>
      <tbody>
          <% req.POST.sort_by { |k, v| k.to_s }.each { |key, val| %>
          <tr>
            <td><%=h key %></td>
            <td class="code"><div><%=h val.inspect %></div></td>
          </tr>
          <% } %>
      </tbody>
    </table>
  <% else %>
    <p>No POST data.</p>
  <% end %>


  <h3 id="cookie-info">COOKIES</h3>
  <% unless req.cookies.empty? %>
    <table class="req">
      <thead>
        <tr>
          <th>Variable</th>
          <th>Value</th>
        </tr>
      </thead>
      <tbody>
        <% req.cookies.each { |key, val| %>
          <tr>
            <td><%=h key %></td>
            <td class="code"><div><%=h val.inspect %></div></td>
          </tr>
        <% } %>
      </tbody>
    </table>
  <% else %>
    <p>No cookie data.</p>
  <% end %>

  <h3 id="env-info">Rack ENV</h3>
    <table class="req">
      <thead>
        <tr>
          <th>Variable</th>
          <th>Value</th>
        </tr>
      </thead>
      <tbody>
          <% env.sort_by { |k, v| k.to_s }.each { |key, val| %>
          <tr>
            <td><%=h key %></td>
            <td class="code"><div><%=h val %></div></td>
          </tr>
          <% } %>
      </tbody>
    </table>

</div>

<div id="explanation">
  <p>
    You're seeing this error because you use <code>Rack::ShowException</code>.
  </p>
</div>

</body>
</html>
HTML

Instance Method Summary collapse

Constructor Details

#initialize(app) ⇒ ShowExceptions

Returns a new instance of ShowExceptions.



17
18
19
20
 
# File 'lib/rack/showexceptions.rb', line 17

def initialize(app)
  @app = app
  @template = ERB.new(TEMPLATE)
end

Instance Method Details

#call(env) ⇒ Object 



22
23
24
25
26
 
# File 'lib/rack/showexceptions.rb', line 22

def call(env)
  @app.call(env)
rescue StandardError, LoadError, SyntaxError => e
  [500, {"Content-Type" => "text/html"}, pretty(env, e)]
end

#h(obj) ⇒ Object

:nodoc:



63
64
65
66
67
68
69
70
 
# File 'lib/rack/showexceptions.rb', line 63

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

#pretty(env, exception) ⇒ Object 



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
 
# File 'lib/rack/showexceptions.rb', line 28

def pretty(env, exception)
  req = Rack::Request.new(env)
  path = (req.script_name + req.path_info).squeeze("/")

  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

  env["rack.errors"].puts "#{exception.class}: #{exception.message}"
  env["rack.errors"].puts exception.backtrace.map { |l| "\t" + l }
  env["rack.errors"].flush

  [@template.result(binding)]
end