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from __future__ import unicode_literals
import logging
import sys
import types
from django import http
from django.conf import settings
from django.core import signals, urlresolvers
from django.core.exceptions import (
MiddlewareNotUsed, PermissionDenied, SuspiciousOperation,
)
from django.db import connections, transaction
from django.http.multipartparser import MultiPartParserError
from django.utils import six
from django.utils.encoding import force_text
from django.utils.module_loading import import_string
from django.views import debug
logger = logging.getLogger('django.request')
class BaseHandler(object):
# Changes that are always applied to a response (in this order).
response_fixes = [
http.conditional_content_removal,
]
def __init__(self):
self._request_middleware = None
self._view_middleware = None
self._template_response_middleware = None
self._response_middleware = None
self._exception_middleware = None
def load_middleware(self):
"""
Populate middleware lists from settings.MIDDLEWARE_CLASSES.
Must be called after the environment is fixed (see __call__ in subclasses).
"""
self._view_middleware = []
self._template_response_middleware = []
self._response_middleware = []
self._exception_middleware = []
request_middleware = []
for middleware_path in settings.MIDDLEWARE_CLASSES:
mw_class = import_string(middleware_path)
try:
mw_instance = mw_class()
except MiddlewareNotUsed as exc:
if settings.DEBUG:
if six.text_type(exc):
logger.debug('MiddlewareNotUsed(%r): %s', middleware_path, exc)
else:
logger.debug('MiddlewareNotUsed: %r', middleware_path)
continue
if hasattr(mw_instance, 'process_request'):
request_middleware.append(mw_instance.process_request)
if hasattr(mw_instance, 'process_view'):
self._view_middleware.append(mw_instance.process_view)
if hasattr(mw_instance, 'process_template_response'):
self._template_response_middleware.insert(0, mw_instance.process_template_response)
if hasattr(mw_instance, 'process_response'):
self._response_middleware.insert(0, mw_instance.process_response)
if hasattr(mw_instance, 'process_exception'):
self._exception_middleware.insert(0, mw_instance.process_exception)
# We only assign to this when initialization is complete as it is used
# as a flag for initialization being complete.
self._request_middleware = request_middleware
def make_view_atomic(self, view):
non_atomic_requests = getattr(view, '_non_atomic_requests', set())
for db in connections.all():
if (db.settings_dict['ATOMIC_REQUESTS']
and db.alias not in non_atomic_requests):
view = transaction.atomic(using=db.alias)(view)
return view
def get_exception_response(self, request, resolver, status_code):
try:
callback, param_dict = resolver.resolve_error_handler(status_code)
response = callback(request, **param_dict)
except:
signals.got_request_exception.send(sender=self.__class__, request=request)
response = self.handle_uncaught_exception(request, resolver, sys.exc_info())
return response
def get_response(self, request):
"Returns an HttpResponse object for the given HttpRequest"
# Setup default url resolver for this thread, this code is outside
# the try/except so we don't get a spurious "unbound local
# variable" exception in the event an exception is raised before
# resolver is set
urlconf = settings.ROOT_URLCONF
urlresolvers.set_urlconf(urlconf)
resolver = urlresolvers.RegexURLResolver(r'^/', urlconf)
try:
response = None
# Apply request middleware
for middleware_method in self._request_middleware:
response = middleware_method(request)
if response:
break
if response is None:
if hasattr(request, 'urlconf'):
# Reset url resolver with a custom urlconf.
urlconf = request.urlconf
urlresolvers.set_urlconf(urlconf)
resolver = urlresolvers.RegexURLResolver(r'^/', urlconf)
resolver_match = resolver.resolve(request.path_info)
callback, callback_args, callback_kwargs = resolver_match
request.resolver_match = resolver_match
# Apply view middleware
for middleware_method in self._view_middleware:
response = middleware_method(request, callback, callback_args, callback_kwargs)
if response:
break
if response is None:
wrapped_callback = self.make_view_atomic(callback)
try:
response = wrapped_callback(request, *callback_args, **callback_kwargs)
except Exception as e:
# If the view raised an exception, run it through exception
# middleware, and if the exception middleware returns a
# response, use that. Otherwise, reraise the exception.
for middleware_method in self._exception_middleware:
response = middleware_method(request, e)
if response:
break
if response is None:
raise
# Complain if the view returned None (a common error).
if response is None:
if isinstance(callback, types.FunctionType): # FBV
view_name = callback.__name__
else: # CBV
view_name = callback.__class__.__name__ + '.__call__'
raise ValueError("The view %s.%s didn't return an HttpResponse object. It returned None instead."
% (callback.__module__, view_name))
# If the response supports deferred rendering, apply template
# response middleware and then render the response
if hasattr(response, 'render') and callable(response.render):
for middleware_method in self._template_response_middleware:
response = middleware_method(request, response)
# Complain if the template response middleware returned None (a common error).
if response is None:
raise ValueError(
"%s.process_template_response didn't return an "
"HttpResponse object. It returned None instead."
% (middleware_method.__self__.__class__.__name__))
response = response.render()
except http.Http404 as e:
logger.warning('Not Found: %s', request.path,
extra={
'status_code': 404,
'request': request
})
if settings.DEBUG:
response = debug.technical_404_response(request, e)
else:
response = self.get_exception_response(request, resolver, 404)
except PermissionDenied:
logger.warning(
'Forbidden (Permission denied): %s', request.path,
extra={
'status_code': 403,
'request': request
})
response = self.get_exception_response(request, resolver, 403)
except MultiPartParserError:
logger.warning(
'Bad request (Unable to parse request body): %s', request.path,
extra={
'status_code': 400,
'request': request
})
response = self.get_exception_response(request, resolver, 400)
except SuspiciousOperation as e:
# The request logger receives events for any problematic request
# The security logger receives events for all SuspiciousOperations
security_logger = logging.getLogger('django.security.%s' %
e.__class__.__name__)
security_logger.error(
force_text(e),
extra={
'status_code': 400,
'request': request
})
if settings.DEBUG:
return debug.technical_500_response(request, *sys.exc_info(), status_code=400)
response = self.get_exception_response(request, resolver, 400)
except SystemExit:
# Allow sys.exit() to actually exit. See tickets #1023 and #4701
raise
except: # Handle everything else.
# Get the exception info now, in case another exception is thrown later.
signals.got_request_exception.send(sender=self.__class__, request=request)
response = self.handle_uncaught_exception(request, resolver, sys.exc_info())
try:
# Apply response middleware, regardless of the response
for middleware_method in self._response_middleware:
response = middleware_method(request, response)
# Complain if the response middleware returned None (a common error).
if response is None:
raise ValueError(
"%s.process_response didn't return an "
"HttpResponse object. It returned None instead."
% (middleware_method.__self__.__class__.__name__))
response = self.apply_response_fixes(request, response)
except: # Any exception should be gathered and handled
signals.got_request_exception.send(sender=self.__class__, request=request)
response = self.handle_uncaught_exception(request, resolver, sys.exc_info())
response._closable_objects.append(request)
return response
def handle_uncaught_exception(self, request, resolver, exc_info):
"""
Processing for any otherwise uncaught exceptions (those that will
generate HTTP 500 responses). Can be overridden by subclasses who want
customised 500 handling.
Be *very* careful when overriding this because the error could be
caused by anything, so assuming something like the database is always
available would be an error.
"""
if settings.DEBUG_PROPAGATE_EXCEPTIONS:
raise
logger.error('Internal Server Error: %s', request.path,
exc_info=exc_info,
extra={
'status_code': 500,
'request': request
}
)
if settings.DEBUG:
return debug.technical_500_response(request, *exc_info)
# If Http500 handler is not installed, re-raise last exception
if resolver.urlconf_module is None:
six.reraise(*exc_info)
# Return an HttpResponse that displays a friendly error message.
callback, param_dict = resolver.resolve_error_handler(500)
return callback(request, **param_dict)
def apply_response_fixes(self, request, response):
"""
Applies each of the functions in self.response_fixes to the request and
response, modifying the response in the process. Returns the new
response.
"""
for func in self.response_fixes:
response = func(request, response)
return response
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