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middleware.py @ 3

リビジョン 3, 24.7 KB (コミッタ: kohda, 14 年前)
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1	"""Exception-catching middleware that allows interactive debugging.
2
3	This middleware catches all unexpected exceptions. A normal
4	traceback, like produced by
5	``weberror.exceptions.errormiddleware.ErrorMiddleware`` is given, plus
6	controls to see local variables and evaluate expressions in a local
7	context.
8
9	This can only be used in single-process environments, because
10	subsequent requests must go back to the same process that the
11	exception originally occurred in. Threaded or non-concurrent
12	environments both work.
13
14	This shouldn't be used in production in any way. That would just be
15	silly.
16
17	If calling from an XMLHttpRequest call, if the GET variable ``_`` is
18	given then it will make the response more compact (and less
19	Javascripty), since if you use innerHTML it'll kill your browser. You
20	can look for the header X-Debug-URL in your 500 responses if you want
21	to see the full debuggable traceback. Also, this URL is printed to
22	``wsgi.errors``, so you can open it up in another browser window.
23
24	"""
25	import sys
26	import os
27	import cgi
28	import traceback
29	from cStringIO import StringIO
30	import pprint
31	import itertools
32	import time
33	import re
34
35	from pkg_resources import resource_filename
36
37	from paste import urlparser
38	from paste import registry
39	from paste import request
40
41	import evalcontext
42	from weberror.exceptions import errormiddleware, formatter, collector
43	from tempita import HTMLTemplate
44	from webob import Request, Response
45	from webob import exc
46	from weberror.util import PySourceColor
47
48	limit = 200
49
50	def html_quote(v):
51	"""
52	Escape HTML characters, plus translate None to ''
53	"""
54	if v is None:
55	return ''
56	return cgi.escape(str(v), 1)
57
58
59	def preserve_whitespace(v, quote=True):
60	"""
61	Quote a value for HTML, preserving whitespace (translating
62	newlines to ``<br>`` and multiple spaces to use `` ``).
63
64	If ``quote`` is true, then the value will be HTML quoted first.
65	"""
66	if quote:
67	v = html_quote(v)
68	v = v.replace('\n', '<br>\n')
69	v = re.sub(r'()( +)', _repl_nbsp, v)
70	v = re.sub(r'(\n)( +)', _repl_nbsp, v)
71	v = re.sub(r'^()( +)', _repl_nbsp, v)
72	return '<code>%s</code>' % v
73
74
75	def _repl_nbsp(match):
76	if len(match.group(2)) == 1:
77	return ' '
78	return match.group(1) + ' ' * (len(match.group(2))-1) + ' '
79
80
81	def simplecatcher(application):
82	"""
83	A simple middleware that catches errors and turns them into simple
84	tracebacks.
85	"""
86	def simplecatcher_app(environ, start_response):
87	try:
88	return application(environ, start_response)
89	except:
90	out = StringIO()
91	traceback.print_exc(file=out)
92	start_response('500 Server Error',
93	[('content-type', 'text/html')],
94	sys.exc_info())
95	res = out.getvalue()
96	return ['<h3>Error</h3><pre>%s</pre>'
97	% html_quote(res)]
98	return simplecatcher_app
99
100
101	def wsgiapp():
102	"""
103	Turns a function or method into a WSGI application.
104	"""
105	def decorator(func):
106	def wsgiapp_wrapper(*args):
107	# we get 3 args when this is a method, two when it is
108	# a function :(
109	if len(args) == 3:
110	environ = args[1]
111	start_response = args[2]
112	args = [args[0]]
113	else:
114	environ, start_response = args
115	args = []
116	def application(environ, start_response):
117	form = request.parse_formvars(environ,
118	include_get_vars=True)
119	status = '200 OK'
120	form['environ'] = environ
121	try:
122	res = func(args, *form.mixed())
123	except ValueError, ve:
124	status = '500 Server Error'
125	res = '<html>There was an error: %s</html>' % \
126	html_quote(ve)
127	start_response(status, [('content-type', 'text/html')])
128	return [res]
129	app = simplecatcher(application)
130	return app(environ, start_response)
131	wsgiapp_wrapper.exposed = True
132	return wsgiapp_wrapper
133	return decorator
134
135
136	def get_debug_info(func):
137	"""
138	A decorator (meant to be used under ``wsgiapp()``) that resolves
139	the ``debugcount`` variable to a ``DebugInfo`` object (or gives an
140	error if it can't be found).
141	"""
142	def debug_info_replacement(self, req):
143	if 'debugcount' not in req.params:
144	return exc.HTTPBadRequest(
145	"You must provide a debugcount parameter")
146	debugcount = req.params['debugcount']
147	try:
148	debugcount = int(debugcount)
149	except ValueError, e:
150	return exc.HTTPBadRequest(
151	"Invalid value for debugcount (%r): %s"
152	% (debugcount, e))
153	if debugcount not in self.debug_infos:
154	return exc.HTTPServerError(
155	"Debug %s not found (maybe it has expired, or the server was restarted)"
156	% debugcount)
157	req.debug_info = self.debug_infos[debugcount]
158	return func(self, req)
159	debug_info_replacement.exposed = True
160	return debug_info_replacement
161
162	debug_counter = itertools.count(int(time.time()))
163
164	def get_debug_count(req):
165	"""
166	Return the unique debug count for the current request
167	"""
168	if hasattr(req, 'environ'):
169	environ = req.environ
170	else:
171	environ = req
172	# XXX: Legacy support for Paste restorer
173	if 'paste.evalexception.debug_count' in environ:
174	return environ['paste.evalexception.debug_count']
175	elif 'weberror.evalexception.debug_count' in environ:
176	return environ['weberror.evalexception.debug_count']
177	else:
178	next = debug_counter.next()
179	environ['weberror.evalexception.debug_count'] = next
180	environ['paste.evalexception.debug_count'] = next
181	return next
182
183
184	class InvalidTemplate(Exception):
185	pass
186
187
188	class EvalException(object):
189	"""Handles capturing an exception and turning it into an interactive
190	exception explorer"""
191	def __init__(self, application, global_conf=None,
192	error_template_filename=None,
193	xmlhttp_key=None, media_paths=None,
194	templating_formatters=None, head_html='', footer_html='',
195	**params):
196	self.application = application
197	self.debug_infos = {}
198	self.templating_formatters = templating_formatters or []
199	self.head_html = HTMLTemplate(head_html)
200	self.footer_html = HTMLTemplate(footer_html)
201	if error_template_filename is None:
202	error_template_filename = resource_filename( "weberror.evalexception",
203	"error_template.html.tmpl" )
204	if xmlhttp_key is None:
205	if global_conf is None:
206	xmlhttp_key = '_'
207	else:
208	xmlhttp_key = global_conf.get('xmlhttp_key', '_')
209	self.xmlhttp_key = xmlhttp_key
210	self.media_paths = media_paths or {}
211	self.error_template = HTMLTemplate.from_filename(error_template_filename)
212
213	def __call__(self, environ, start_response):
214	## FIXME: print better error message (maybe fall back on
215	## normal middleware, plus an error message)
216	assert not environ['wsgi.multiprocess'], (
217	"The EvalException middleware is not usable in a "
218	"multi-process environment")
219	# XXX: Legacy support for Paste restorer
220	environ['weberror.evalexception'] = environ['paste.evalexception'] = \
221	self
222	req = Request(environ)
223	if req.path_info_peek() == '_debug':
224	return self.debug(req)(environ, start_response)
225	else:
226	return self.respond(environ, start_response)
227
228	def debug(self, req):
229	assert req.path_info_pop() == '_debug'
230	next_part = req.path_info_pop()
231	method = getattr(self, next_part, None)
232	if method is None:
233	return exc.HTTPNotFound('Nothing could be found to match %r' % next_part)
234	if not getattr(method, 'exposed', False):
235	return exc.HTTPForbidden('Access to %r is forbidden' % next_part)
236	return method(req)
237
238	def media(self, req):
239	"""Static path where images and other files live"""
240	first_part = req.path_info_peek()
241	if first_part in self.media_paths:
242	req.path_info_pop()
243	path = self.media_paths[first_part]
244	else:
245	path = resource_filename("weberror.evalexception", "media")
246	app = urlparser.StaticURLParser(path)
247	return app
248	media.exposed = True
249
250	def summary(self, req):
251	"""
252	Returns a JSON-format summary of all the cached
253	exception reports
254	"""
255	res = Response(content_type='text/x-json')
256	data = [];
257	items = self.debug_infos.values()
258	items.sort(lambda a, b: cmp(a.created, b.created))
259	data = [item.json() for item in items]
260	res.body = repr(data)
261	return res
262	summary.exposed = True
263
264	def view(self, req):
265	"""
266	View old exception reports
267	"""
268	id = int(req.path_info_pop())
269	if id not in self.debug_infos:
270	return exc.HTTPServerError(
271	"Traceback by id %s does not exist (maybe "
272	"the server has been restarted?)" % id)
273	debug_info = self.debug_infos[id]
274	return debug_info.wsgi_application
275	view.exposed = True
276
277	def make_view_url(self, environ, base_path, count):
278	return base_path + '/view/%s' % count
279
280	#@get_debug_info
281	def show_frame(self, req):
282	tbid = int(req.params['tbid'])
283	frame = req.debug_info.frame(tbid)
284	vars = frame.tb_frame.f_locals
285	if vars:
286	registry.restorer.restoration_begin(req.debug_info.counter)
287	try:
288	local_vars = make_table(vars)
289	finally:
290	registry.restorer.restoration_end()
291	else:
292	local_vars = 'No local vars'
293	res = Response(content_type='text/html')
294	res.body = input_form.substitute(tbid=tbid, debug_info=req.debug_info) + local_vars
295	return res
296
297	show_frame = get_debug_info(show_frame)
298
299	#@get_debug_info
300	def exec_input(self, req):
301	input = req.params.get('input')
302	if not input.strip():
303	return ''
304	input = input.rstrip() + '\n'
305	frame = req.debug_info.frame(int(req.params['tbid']))
306	vars = frame.tb_frame.f_locals
307	glob_vars = frame.tb_frame.f_globals
308	context = evalcontext.EvalContext(vars, glob_vars)
309	registry.restorer.restoration_begin(req.debug_info.counter)
310	try:
311	output = context.exec_expr(input)
312	finally:
313	registry.restorer.restoration_end()
314	input_html = formatter.str2html(input)
315	res = Response(content_type='text/html')
316	res.body = (
317	'<code style="color: #060">>>></code> '
318	'<code>%s</code><br>\n%s'
319	% (preserve_whitespace(input_html, quote=False),
320	preserve_whitespace(output)))
321	return res
322
323	exec_input = get_debug_info(exec_input)
324
325	def source_code(self, req):
326	location = req.params['location']
327	module_name, lineno = location.split(':', 1)
328	module = sys.modules[module_name]
329	filename = module.__file__
330	if filename.endswith('.pyc'):
331	filename = filename[:-1]
332	f = open(filename, 'rb')
333	source = f.read()
334	f.close()
335	html = (
336	('<div>Module: <b>%s</b> file: %s</div>'
337	% (module_name, filename))
338	+ PySourceColor.str2html(source, form='snip', linenumbers=-1))
339	source_lines = len(source.splitlines())
340	if source_lines < 60:
341	html += '\n<br>'*(60-source_lines)
342	res = Response(content_type='text/html', charset='utf8')
343	res.body = html
344	return res
345
346	source_code.exposed = True
347
348	def respond(self, environ, start_response):
349	req = Request(environ)
350	if req.environ.get('paste.throw_errors'):
351	return self.application(environ, start_response)
352	base_path = req.application_url + '/_debug'
353	req.environ['paste.throw_errors'] = True
354	started = []
355	def detect_start_response(status, headers, exc_info=None):
356	try:
357	return start_response(status, headers, exc_info)
358	except:
359	raise
360	else:
361	started.append(True)
362	try:
363	__traceback_supplement__ = errormiddleware.Supplement, self, environ
364	app_iter = self.application(environ, detect_start_response)
365	try:
366	return_iter = list(app_iter)
367	return return_iter
368	finally:
369	if hasattr(app_iter, 'close'):
370	app_iter.close()
371	except:
372	exc_info = sys.exc_info()
373
374	# Tell the Registry to save its StackedObjectProxies current state
375	# for later restoration
376	## FIXME: needs to be more abstract (something in the environ)
377	## to remove the Paste dependency
378	registry.restorer.save_registry_state(environ)
379
380	count = get_debug_count(environ)
381	view_uri = self.make_view_url(environ, base_path, count)
382	if not started:
383	headers = [('content-type', 'text/html')]
384	headers.append(('X-Debug-URL', view_uri))
385	start_response('500 Internal Server Error',
386	headers,
387	exc_info)
388	environ['wsgi.errors'].write('Debug at: %s\n' % view_uri)
389
390	exc_data = collector.collect_exception(*exc_info)
391	debug_info = DebugInfo(count, exc_info, exc_data, base_path,
392	environ, view_uri, self.error_template,
393	self.templating_formatters, self.head_html,
394	self.footer_html)
395	assert count not in self.debug_infos
396	self.debug_infos[count] = debug_info
397
398	if self.xmlhttp_key:
399	if self.xmlhttp_key in req.params:
400	exc_data = collector.collect_exception(*exc_info)
401	html, extra_html = formatter.format_html(
402	exc_data, include_hidden_frames=False,
403	include_reusable=False, show_extra_data=False)
404	return [html, extra_html]
405
406	# @@: it would be nice to deal with bad content types here
407	return debug_info.content()
408
409
410	class DebugInfo(object):
411
412	def __init__(self, counter, exc_info, exc_data, base_path,
413	environ, view_uri, error_template, templating_formatters,
414	head_html, footer_html):
415	self.counter = counter
416	self.exc_data = exc_data
417	self.base_path = base_path
418	self.environ = environ
419	self.view_uri = view_uri
420	self.error_template = error_template
421	self.created = time.time()
422	self.templating_formatters = templating_formatters
423	self.head_html = head_html
424	self.footer_html = footer_html
425	self.exc_type, self.exc_value, self.tb = exc_info
426	__exception_formatter__ = 1
427	self.frames = []
428	n = 0
429	tb = self.tb
430	while tb is not None and (limit is None or n < limit):
431	if tb.tb_frame.f_locals.get('__exception_formatter__'):
432	# Stop recursion. @@: should make a fake ExceptionFrame
433	break
434	self.frames.append(tb)
435	tb = tb.tb_next
436	n += 1
437
438	def json(self):
439	"""Return the JSON-able representation of this object"""
440	return {
441	'uri': self.view_uri,
442	'created': time.strftime('%c', time.gmtime(self.created)),
443	'created_timestamp': self.created,
444	'exception_type': str(self.exc_type),
445	'exception': str(self.exc_value),
446	}
447
448	def frame(self, tbid):
449	for frame in self.frames:
450	if id(frame) == tbid:
451	return frame
452	else:
453	raise ValueError, (
454	"No frame by id %s found from %r" % (tbid, self.frames))
455
456	def wsgi_application(self, environ, start_response):
457	start_response('200 OK', [('content-type', 'text/html')])
458	return self.content()
459
460	def content(self):
461	traceback_body, extra_data = format_eval_html(self.exc_data, self.base_path, self.counter)
462	repost_button = make_repost_button(self.environ)
463	template_data = '<p>No Template information available.</p>'
464	tab = 'traceback_data'
465
466	for tmpl_formatter in self.templating_formatters:
467	result = tmpl_formatter(self.exc_value)
468	if result:
469	tab = 'template_data'
470	template_data = result
471	break
472
473	template_data = template_data.replace('<h2>', '<h1 class="first">')
474	template_data = template_data.replace('</h2>', '</h1>')
475	if hasattr(self.exc_data.exception_type, '__name__'):
476	exc_name = self.exc_data.exception_type.__name__
477	else:
478	exc_name = str(self.exc_data.exception_type)
479	page = self.error_template.substitute(
480	head_html=self.head_html.substitute(prefix=self.base_path),
481	footer_html=self.footer_html.substitute(prefix=self.base_path),
482	repost_button=repost_button or '',
483	traceback_body=traceback_body,
484	exc_data=self.exc_data,
485	exc_name=exc_name,
486	extra_data=extra_data,
487	template_data=template_data,
488	set_tab=tab,
489	prefix=self.base_path,
490	counter=self.counter,
491	)
492	return [page]
493
494	class EvalHTMLFormatter(formatter.HTMLFormatter):
495
496	def __init__(self, base_path, counter, **kw):
497	super(EvalHTMLFormatter, self).__init__(**kw)
498	self.base_path = base_path
499	self.counter = counter
500
501	def format_source_line(self, filename, frame):
502	line = formatter.HTMLFormatter.format_source_line(
503	self, filename, frame)
504	location = '%s:%s' % (frame.modname, frame.lineno)
505	return (line +
506	' <a href="#" class="switch_source" '
507	'tbid="%s" onClick="return showFrame(this)">    '
508	'<img src="%s/media/plus.jpg" border=0 width=9 '
509	'height=9>    </a> '
510	'<a href="#" class="" location="%s" '
511	'onClick="return showSource(this)">view</a>'
512	% (frame.tbid, self.base_path, location))
513
514
515	def make_table(items):
516	if isinstance(items, dict):
517	items = items.items()
518	items.sort()
519	return table_template.substitute(
520	html_quote=html_quote,
521	items=items,
522	preserve_whitespace=preserve_whitespace,
523	make_wrappable=formatter.make_wrappable,
524	pprint_format=pprint_format)
525
526	table_template = HTMLTemplate('''
527	{{py:i = 0}}
528	<table>
529	{{for name, value in items:}}
530	{{py:i += 1}}
531	{{py:
532	value_html = html_quote(pprint_format(value, safe=True))
533	value_html = make_wrappable(value_html)
534	if len(value_html) > 100:
535	## FIXME: This can break HTML; truncate before quoting?
536	value_html, expand_html = value_html[:100], value_html[100:]
537	else:
538	expand_html = ''
539	}}
540	<tr class="{{if i%2}}even{{else}}odd{{endif}}"
541	style="vertical-align: top">
542	<td><b>{{name}}</b></td>
543	<td style="overflow: auto">{{preserve_whitespace(value_html, quote=False)\|html}}{{if expand_html}}
544	<a class="switch_source" style="background-color: #999" href="#" onclick="return expandLong(this)">...</a>
545	<span style="display: none">{{expand_html\|html}}</span>
546	{{endif}}
547	</td>
548	</tr>
549	{{endfor}}
550	</table>
551	''', name='table_template')
552
553	def pprint_format(value, safe=False):
554	out = StringIO()
555	try:
556	pprint.pprint(value, out)
557	except Exception, e:
558	if safe:
559	out.write('Error: %s' % e)
560	else:
561	raise
562	return out.getvalue()
563
564	def format_eval_html(exc_data, base_path, counter):
565	short_formatter = EvalHTMLFormatter(
566	base_path=base_path,
567	counter=counter,
568	include_reusable=False)
569	short_er, extra_data = short_formatter.format_collected_data(exc_data)
570	short_text_er, text_extra_data = formatter.format_text(exc_data, show_extra_data=False)
571	long_formatter = EvalHTMLFormatter(
572	base_path=base_path,
573	counter=counter,
574	show_hidden_frames=True,
575	show_extra_data=False,
576	include_reusable=False)
577	long_er, extra_data_none = long_formatter.format_collected_data(exc_data)
578	long_text_er = formatter.format_text(exc_data, show_hidden_frames=True,
579	show_extra_data=False)[0]
580	long_xml_er = formatter.format_xml(exc_data, show_hidden_frames=True,
581	show_extra_data=False)[0]
582	short_xml_er = formatter.format_xml(exc_data, show_hidden_frames=False,
583	show_extra_data=False)[0]
584
585	if short_formatter.filter_frames(exc_data.frames) != \
586	long_formatter.filter_frames(exc_data.frames):
587	# Only display the full traceback when it differs from the
588	# short version
589	long_text_er = cgi.escape(long_text_er)
590	full_traceback_html = """
591	<div id="full_traceback" class="hidden-data">
592	%s
593	</div>
594	<div id="long_text_version" class="hidden-data">
595	<textarea style="width: 100%%" rows=%s cols=60>%s</textarea>
596	</div>
597	""" % (long_er, len(long_text_er.splitlines()), long_text_er)
598	else:
599	full_traceback_html = ''
600
601	short_text_er = cgi.escape(short_text_er)
602
603	long_xml_leng = len(long_xml_er.splitlines())
604	if long_xml_leng > 50:
605	long_xml_leng = 50
606
607	short_xml_leng = len(short_xml_er.splitlines())
608	if short_xml_leng > 50:
609	short_xml_leng = 50
610
611	return """
612	<div id="short_traceback">
613	%s
614	</div>
615	<div id="short_text_version" class="hidden-data">
616	<textarea style="width: 100%%" rows=%s cols=60>%s</textarea>
617	</div>
618	<div id="long_xml_version" class="hidden-data">
619	<textarea style="width: 100%%" rows=%s cols=60>%s</textarea>
620	</div>
621	<div id="short_xml_version" class="hidden-data">
622	<textarea style="width: 100%%" rows=%s cols=60>%s</textarea>
623	</div>
624	%s
625	""" % (short_er, len(short_text_er.splitlines()), short_text_er,
626	long_xml_leng, cgi.escape(long_xml_er),
627	short_xml_leng, cgi.escape(short_xml_er),
628	full_traceback_html), extra_data
629
630	def make_repost_button(environ):
631	url = request.construct_url(environ)
632	if environ['REQUEST_METHOD'] == 'GET':
633	return ('<button onclick="window.location.href=%r">'
634	'Re-GET Page</button><br>' % url)
635	else:
636	# @@: I'd like to reconstruct this, but I can't because
637	# the POST body is probably lost at this point, and
638	# I can't get it back :(
639	return None
640	# @@: Use or lose the following code block
641	"""
642	fields = []
643	for name, value in request.parse_formvars(
644	environ, include_get_vars=False).items():
645	if hasattr(value, 'filename'):
646	# @@: Arg, we'll just submit the body, and leave out
647	# the filename :(
648	value = value.value
649	fields.append(
650	'<input type="hidden" name="%s" value="%s">'
651	% (html_quote(name), html_quote(value)))
652	return '''
653	<form action="%s" method="POST">
654	%s
655	<input type="submit" value="Re-POST Page">
656	</form>''' % (url, '\n'.join(fields))
657	"""
658
659
660	input_form = HTMLTemplate('''
661	<form action="#" method="POST"
662	onsubmit="return submitInput($(\'#submit_{{tbid}}\').get(0), {{tbid}})">
663	<div id="exec-output-{{tbid}}" style="width: 95%;
664	padding: 5px; margin: 5px; border: 2px solid #000;
665	display: none"></div>
666	<input type="text" name="input" id="debug_input_{{tbid}}"
667	style="width: 100%"
668	autocomplete="off" onkeypress="upArrow(this, event)"><br>
669	<input type="submit" value="Execute" name="submitbutton"
670	onclick="return submitInput(this, {{tbid}})"
671	id="submit_{{tbid}}"
672	input-from="debug_input_{{tbid}}"
673	output-to="exec-output-{{tbid}}">
674	<input type="submit" value="Expand"
675	onclick="return expandInput(this)">
676	</form>
677	''', name='input_form')
678
679
680	def make_eval_exception(app, global_conf, xmlhttp_key=None):
681	"""
682	Wraps the application in an interactive debugger.
683
684	This debugger is a major security hole, and should only be
685	used during development.
686
687	xmlhttp_key is a string that, if present in QUERY_STRING,
688	indicates that the request is an XMLHttp request, and the
689	Javascript/interactive debugger should not be returned. (If you
690	try to put the debugger somewhere with innerHTML, you will often
691	crash the browser)
692	"""
693	if xmlhttp_key is None:
694	xmlhttp_key = global_conf.get('xmlhttp_key', '_')
695	return EvalException(app, xmlhttp_key=xmlhttp_key)

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