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show_exceptions.rb
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show_exceptions.rb
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# frozen_string_literal: true
require 'erb'
require_relative 'constants'
require_relative 'utils'
require_relative 'request'
module Rack
# 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.
class ShowExceptions
CONTEXT = 7
Frame = Struct.new(:filename, :lineno, :function,
:pre_context_lineno, :pre_context,
:context_line, :post_context_lineno,
:post_context)
def initialize(app)
@app = app
end
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
def prefers_plaintext?(env)
!accepts_html?(env)
end
def accepts_html?(env)
Rack::Utils.best_q_match(env["HTTP_ACCEPT"], %w[text/html])
end
private :accepts_html?
def dump_exception(exception)
if exception.respond_to?(:detailed_message)
message = exception.detailed_message(highlight: false)
else
message = exception.message
end
string = "#{exception.class}: #{message}\n".dup
string << exception.backtrace.map { |l| "\t#{l}" }.join("\n")
string
end
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 = Frame.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
def template
TEMPLATE
end
def h(obj) # :nodoc:
case obj
when String
Utils.escape_html(obj)
else
Utils.escape_html(obj.inspect)
end
end
# :stopdoc:
# adapted from Django <www.djangoproject.com>
# Copyright (c) Django Software Foundation and individual contributors.
# Used under the modified BSD license:
# http://www.xfree86.org/3.3.6/COPYRIGHT2.html#5
TEMPLATE = ERB.new(<<-'HTML'.gsub(/^ /, ''))
<!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-family: monospace; font-weight: normal; color: #666; white-space: pre-wrap; }
#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>
<% if exception.respond_to?(:detailed_message) %>
<h2><%=h exception.detailed_message(highlight: false) %></h2>
<% else %>
<h2><%=h exception.message %></h2>
<% end %>
<table><tr>
<th>Ruby</th>
<td>
<% if first = frames.first %>
<code><%=h first.filename %></code>: in <code><%=h first.function %></code>, line <%=h frames.first.lineno %>
<% else %>
unknown location
<% end %>
</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>
<% if req.GET and not 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>
<% if ((req.POST and not req.POST.empty?) rescue (no_post_data = "Invalid POST data"; nil)) %>
<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 || "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.inspect %></div></td>
</tr>
<% } %>
</tbody>
</table>
</div>
<div id="explanation">
<p>
You're seeing this error because you use <code>Rack::ShowExceptions</code>.
</p>
</div>
</body>
</html>
HTML
# :startdoc:
end
end