import functools
import re
import sys
import types
from pathlib import Path
from django.conf import settings
from django.http import HttpResponse, HttpResponseNotFound
from django.template import Context, Engine, TemplateDoesNotExist
from django.template.defaultfilters import pprint
from django.urls import Resolver404, resolve
from django.utils import timezone
from django.utils.datastructures import MultiValueDict
from django.utils.encoding import force_text
from django.utils.module_loading import import_string
from django.utils.version import get_docs_version
# Minimal Django templates engine to render the error templates
# regardless of the project's TEMPLATES setting. Templates are
# read directly from the filesystem so that the error handler
# works even if the template loader is broken.
DEBUG_ENGINE = Engine(
debug=True,
libraries={'i18n': 'django.templatetags.i18n'},
)
HIDDEN_SETTINGS = re.compile('API|TOKEN|KEY|SECRET|PASS|SIGNATURE', flags=re.IGNORECASE)
CLEANSED_SUBSTITUTE = '********************'
CURRENT_DIR = Path(__file__).parent
class CallableSettingWrapper:
"""
Object to wrap callable appearing in settings.
* Not to call in the debug page (#21345).
* Not to break the debug page if the callable forbidding to set attributes
(#23070).
"""
def __init__(self, callable_setting):
self._wrapped = callable_setting
def __repr__(self):
return repr(self._wrapped)
def cleanse_setting(key, value):
"""
Cleanse an individual setting key/value of sensitive content. If the value
is a dictionary, recursively cleanse the keys in that dictionary.
"""
try:
if HIDDEN_SETTINGS.search(key):
cleansed = CLEANSED_SUBSTITUTE
else:
if isinstance(value, dict):
cleansed = {k: cleanse_setting(k, v) for k, v in value.items()}
else:
cleansed = value
except TypeError:
# If the key isn't regex-able, just return as-is.
cleansed = value
if callable(cleansed):
# For fixing #21345 and #23070
cleansed = CallableSettingWrapper(cleansed)
return cleansed
def get_safe_settings():
"""
Return a dictionary of the settings module with values of sensitive
settings replaced with stars (*********).
"""
settings_dict = {}
for k in dir(settings):
if k.isupper():
settings_dict[k] = cleanse_setting(k, getattr(settings, k))
return settings_dict
def technical_500_response(request, exc_type, exc_value, tb, status_code=500):
"""
Create a technical server error response. The last three arguments are
the values returned from sys.exc_info() and friends.
"""
reporter = ExceptionReporter(request, exc_type, exc_value, tb)
if request.is_ajax():
text = reporter.get_traceback_text()
return HttpResponse(text, status=status_code, content_type='text/plain; charset=utf-8')
else:
html = reporter.get_traceback_html()
return HttpResponse(html, status=status_code, content_type='text/html')
@functools.lru_cache()
def get_default_exception_reporter_filter():
# Instantiate the default filter for the first time and cache it.
return import_string(settings.DEFAULT_EXCEPTION_REPORTER_FILTER)()
def get_exception_reporter_filter(request):
default_filter = get_default_exception_reporter_filter()
return getattr(request, 'exception_reporter_filter', default_filter)
class ExceptionReporterFilter:
"""
Base for all exception reporter filter classes. All overridable hooks
contain lenient default behaviors.
"""
def get_post_parameters(self, request):
if request is None:
return {}
else:
return request.POST
def get_traceback_frame_variables(self, request, tb_frame):
return list(tb_frame.f_locals.items())
[docs]class SafeExceptionReporterFilter(ExceptionReporterFilter):
"""
Use annotations made by the sensitive_post_parameters and
sensitive_variables decorators to filter out sensitive information.
"""
[docs] def is_active(self, request):
"""
This filter is to add safety in production environments (i.e. DEBUG
is False). If DEBUG is True then your site is not safe anyway.
This hook is provided as a convenience to easily activate or
deactivate the filter on a per request basis.
"""
return settings.DEBUG is False
def get_cleansed_multivaluedict(self, request, multivaluedict):
"""
Replace the keys in a MultiValueDict marked as sensitive with stars.
This mitigates leaking sensitive POST parameters if something like
request.POST['nonexistent_key'] throws an exception (#21098).
"""
sensitive_post_parameters = getattr(request, 'sensitive_post_parameters', [])
if self.is_active(request) and sensitive_post_parameters:
multivaluedict = multivaluedict.copy()
for param in sensitive_post_parameters:
if param in multivaluedict:
multivaluedict[param] = CLEANSED_SUBSTITUTE
return multivaluedict
[docs] def get_post_parameters(self, request):
"""
Replace the values of POST parameters marked as sensitive with
stars (*********).
"""
if request is None:
return {}
else:
sensitive_post_parameters = getattr(request, 'sensitive_post_parameters', [])
if self.is_active(request) and sensitive_post_parameters:
cleansed = request.POST.copy()
if sensitive_post_parameters == '__ALL__':
# Cleanse all parameters.
for k in cleansed:
cleansed[k] = CLEANSED_SUBSTITUTE
return cleansed
else:
# Cleanse only the specified parameters.
for param in sensitive_post_parameters:
if param in cleansed:
cleansed[param] = CLEANSED_SUBSTITUTE
return cleansed
else:
return request.POST
def cleanse_special_types(self, request, value):
try:
# If value is lazy or a complex object of another kind, this check
# might raise an exception. isinstance checks that lazy
# MultiValueDicts will have a return value.
is_multivalue_dict = isinstance(value, MultiValueDict)
except Exception as e:
return '{!r} while evaluating {!r}'.format(e, value)
if is_multivalue_dict:
# Cleanse MultiValueDicts (request.POST is the one we usually care about)
value = self.get_cleansed_multivaluedict(request, value)
return value
[docs] def get_traceback_frame_variables(self, request, tb_frame):
"""
Replace the values of variables marked as sensitive with
stars (*********).
"""
# Loop through the frame's callers to see if the sensitive_variables
# decorator was used.
current_frame = tb_frame.f_back
sensitive_variables = None
while current_frame is not None:
if (current_frame.f_code.co_name == 'sensitive_variables_wrapper' and
'sensitive_variables_wrapper' in current_frame.f_locals):
# The sensitive_variables decorator was used, so we take note
# of the sensitive variables' names.
wrapper = current_frame.f_locals['sensitive_variables_wrapper']
sensitive_variables = getattr(wrapper, 'sensitive_variables', None)
break
current_frame = current_frame.f_back
cleansed = {}
if self.is_active(request) and sensitive_variables:
if sensitive_variables == '__ALL__':
# Cleanse all variables
for name in tb_frame.f_locals:
cleansed[name] = CLEANSED_SUBSTITUTE
else:
# Cleanse specified variables
for name, value in tb_frame.f_locals.items():
if name in sensitive_variables:
value = CLEANSED_SUBSTITUTE
else:
value = self.cleanse_special_types(request, value)
cleansed[name] = value
else:
# Potentially cleanse the request and any MultiValueDicts if they
# are one of the frame variables.
for name, value in tb_frame.f_locals.items():
cleansed[name] = self.cleanse_special_types(request, value)
if (tb_frame.f_code.co_name == 'sensitive_variables_wrapper' and
'sensitive_variables_wrapper' in tb_frame.f_locals):
# For good measure, obfuscate the decorated function's arguments in
# the sensitive_variables decorator's frame, in case the variables
# associated with those arguments were meant to be obfuscated from
# the decorated function's frame.
cleansed['func_args'] = CLEANSED_SUBSTITUTE
cleansed['func_kwargs'] = CLEANSED_SUBSTITUTE
return cleansed.items()
class ExceptionReporter:
"""Organize and coordinate reporting on exceptions."""
def __init__(self, request, exc_type, exc_value, tb, is_email=False):
self.request = request
self.filter = get_exception_reporter_filter(self.request)
self.exc_type = exc_type
self.exc_value = exc_value
self.tb = tb
self.is_email = is_email
self.template_info = getattr(self.exc_value, 'template_debug', None)
self.template_does_not_exist = False
self.postmortem = None
def get_traceback_data(self):
"""Return a dictionary containing traceback information."""
if self.exc_type and issubclass(self.exc_type, TemplateDoesNotExist):
self.template_does_not_exist = True
self.postmortem = self.exc_value.chain or [self.exc_value]
frames = self.get_traceback_frames()
for i, frame in enumerate(frames):
if 'vars' in frame:
frame_vars = []
for k, v in frame['vars']:
v = pprint(v)
# Trim large blobs of data
if len(v) > 4096:
v = '%s… <trimmed %d bytes string>' % (v[0:4096], len(v))
frame_vars.append((k, v))
frame['vars'] = frame_vars
frames[i] = frame
unicode_hint = ''
if self.exc_type and issubclass(self.exc_type, UnicodeError):
start = getattr(self.exc_value, 'start', None)
end = getattr(self.exc_value, 'end', None)
if start is not None and end is not None:
unicode_str = self.exc_value.args[1]
unicode_hint = force_text(
unicode_str[max(start - 5, 0):min(end + 5, len(unicode_str))],
'ascii', errors='replace'
)
from django import get_version
if self.request is None:
user_str = None
else:
try:
user_str = str(self.request.user)
except Exception:
# request.user may raise OperationalError if the database is
# unavailable, for example.
user_str = '[unable to retrieve the current user]'
c = {
'is_email': self.is_email,
'unicode_hint': unicode_hint,
'frames': frames,
'request': self.request,
'user_str': user_str,
'filtered_POST_items': list(self.filter.get_post_parameters(self.request).items()),
'settings': get_safe_settings(),
'sys_executable': sys.executable,
'sys_version_info': '%d.%d.%d' % sys.version_info[0:3],
'server_time': timezone.now(),
'django_version_info': get_version(),
'sys_path': sys.path,
'template_info': self.template_info,
'template_does_not_exist': self.template_does_not_exist,
'postmortem': self.postmortem,
}
if self.request is not None:
c['request_GET_items'] = self.request.GET.items()
c['request_FILES_items'] = self.request.FILES.items()
c['request_COOKIES_items'] = self.request.COOKIES.items()
# Check whether exception info is available
if self.exc_type:
c['exception_type'] = self.exc_type.__name__
if self.exc_value:
c['exception_value'] = str(self.exc_value)
if frames:
c['lastframe'] = frames[-1]
return c
def get_traceback_html(self):
"""Return HTML version of debug 500 HTTP error page."""
with Path(CURRENT_DIR, 'templates', 'technical_500.html').open(encoding='utf-8') as fh:
t = DEBUG_ENGINE.from_string(fh.read())
c = Context(self.get_traceback_data(), use_l10n=False)
return t.render(c)
def get_traceback_text(self):
"""Return plain text version of debug 500 HTTP error page."""
with Path(CURRENT_DIR, 'templates', 'technical_500.txt').open(encoding='utf-8') as fh:
t = DEBUG_ENGINE.from_string(fh.read())
c = Context(self.get_traceback_data(), autoescape=False, use_l10n=False)
return t.render(c)
def _get_lines_from_file(self, filename, lineno, context_lines, loader=None, module_name=None):
"""
Return context_lines before and after lineno from file.
Return (pre_context_lineno, pre_context, context_line, post_context).
"""
source = None
if hasattr(loader, 'get_source'):
try:
source = loader.get_source(module_name)
except ImportError:
pass
if source is not None:
source = source.splitlines()
if source is None:
try:
with open(filename, 'rb') as fp:
source = fp.read().splitlines()
except (OSError, IOError):
pass
if source is None:
return None, [], None, []
# If we just read the source from a file, or if the loader did not
# apply tokenize.detect_encoding to decode the source into a
# string, then we should do that ourselves.
if isinstance(source[0], bytes):
encoding = 'ascii'
for line in source[:2]:
# File coding may be specified. Match pattern from PEP-263
# (https://www.python.org/dev/peps/pep-0263/)
match = re.search(br'coding[:=]\s*([-\w.]+)', line)
if match:
encoding = match.group(1).decode('ascii')
break
source = [str(sline, encoding, 'replace') for sline in source]
lower_bound = max(0, lineno - context_lines)
upper_bound = lineno + context_lines
pre_context = source[lower_bound:lineno]
context_line = source[lineno]
post_context = source[lineno + 1:upper_bound]
return lower_bound, pre_context, context_line, post_context
def get_traceback_frames(self):
def explicit_or_implicit_cause(exc_value):
explicit = getattr(exc_value, '__cause__', None)
implicit = getattr(exc_value, '__context__', None)
return explicit or implicit
# Get the exception and all its causes
exceptions = []
exc_value = self.exc_value
while exc_value:
exceptions.append(exc_value)
exc_value = explicit_or_implicit_cause(exc_value)
frames = []
# No exceptions were supplied to ExceptionReporter
if not exceptions:
return frames
# In case there's just one exception, take the traceback from self.tb
exc_value = exceptions.pop()
tb = self.tb if not exceptions else exc_value.__traceback__
while tb is not None:
# Support for __traceback_hide__ which is used by a few libraries
# to hide internal frames.
if tb.tb_frame.f_locals.get('__traceback_hide__'):
tb = tb.tb_next
continue
filename = tb.tb_frame.f_code.co_filename
function = tb.tb_frame.f_code.co_name
lineno = tb.tb_lineno - 1
loader = tb.tb_frame.f_globals.get('__loader__')
module_name = tb.tb_frame.f_globals.get('__name__') or ''
pre_context_lineno, pre_context, context_line, post_context = self._get_lines_from_file(
filename, lineno, 7, loader, module_name,
)
if pre_context_lineno is None:
pre_context_lineno = lineno
pre_context = []
context_line = '<source code not available>'
post_context = []
frames.append({
'exc_cause': explicit_or_implicit_cause(exc_value),
'exc_cause_explicit': getattr(exc_value, '__cause__', True),
'tb': tb,
'type': 'django' if module_name.startswith('django.') else 'user',
'filename': filename,
'function': function,
'lineno': lineno + 1,
'vars': self.filter.get_traceback_frame_variables(self.request, tb.tb_frame),
'id': id(tb),
'pre_context': pre_context,
'context_line': context_line,
'post_context': post_context,
'pre_context_lineno': pre_context_lineno + 1,
})
# If the traceback for current exception is consumed, try the
# other exception.
if not tb.tb_next and exceptions:
exc_value = exceptions.pop()
tb = exc_value.__traceback__
else:
tb = tb.tb_next
return frames
def technical_404_response(request, exception):
"""Create a technical 404 error response. `exception` is the Http404."""
try:
error_url = exception.args[0]['path']
except (IndexError, TypeError, KeyError):
error_url = request.path_info[1:] # Trim leading slash
try:
tried = exception.args[0]['tried']
except (IndexError, TypeError, KeyError):
tried = []
else:
if (not tried or ( # empty URLconf
request.path == '/' and
len(tried) == 1 and # default URLconf
len(tried[0]) == 1 and
getattr(tried[0][0], 'app_name', '') == getattr(tried[0][0], 'namespace', '') == 'admin'
)):
return default_urlconf(request)
urlconf = getattr(request, 'urlconf', settings.ROOT_URLCONF)
if isinstance(urlconf, types.ModuleType):
urlconf = urlconf.__name__
caller = ''
try:
resolver_match = resolve(request.path)
except Resolver404:
pass
else:
obj = resolver_match.func
if hasattr(obj, '__name__'):
caller = obj.__name__
elif hasattr(obj, '__class__') and hasattr(obj.__class__, '__name__'):
caller = obj.__class__.__name__
if hasattr(obj, '__module__'):
module = obj.__module__
caller = '%s.%s' % (module, caller)
with Path(CURRENT_DIR, 'templates', 'technical_404.html').open() as fh:
t = DEBUG_ENGINE.from_string(fh.read())
c = Context({
'urlconf': urlconf,
'root_urlconf': settings.ROOT_URLCONF,
'request_path': error_url,
'urlpatterns': tried,
'reason': str(exception),
'request': request,
'settings': get_safe_settings(),
'raising_view_name': caller,
})
return HttpResponseNotFound(t.render(c), content_type='text/html')
def default_urlconf(request):
"""Create an empty URLconf 404 error response."""
with Path(CURRENT_DIR, 'templates', 'default_urlconf.html').open() as fh:
t = DEBUG_ENGINE.from_string(fh.read())
c = Context({
'version': get_docs_version(),
})
return HttpResponse(t.render(c), content_type='text/html')
May 01, 2019