import logging import sys from functools import wraps from asgiref.sync import iscoroutinefunction, sync_to_async from django.conf import settings from django.core import signals from django.core.exceptions import ( BadRequest, PermissionDenied, RequestDataTooBig, SuspiciousOperation, TooManyFieldsSent, TooManyFilesSent, ) from django.http import Http404 from django.http.multipartparser import MultiPartParserError from django.urls import get_resolver, get_urlconf from django.utils.log import log_response from django.views import debug def convert_exception_to_response(get_response): """ Wrap the given get_response callable in exception-to-response conversion. All exceptions will be converted. All known 4xx exceptions (Http404, PermissionDenied, MultiPartParserError, SuspiciousOperation) will be converted to the appropriate response, and all other exceptions will be converted to 500 responses. This decorator is automatically applied to all middleware to ensure that no middleware leaks an exception and that the next middleware in the stack can rely on getting a response instead of an exception. """ if iscoroutinefunction(get_response): @wraps(get_response) async def inner(request): try: response = await get_response(request) except Exception as exc: response = await sync_to_async( response_for_exception, thread_sensitive=False )(request, exc) return response return inner else: @wraps(get_response) def inner(request): try: response = get_response(request) except Exception as exc: response = response_for_exception(request, exc) return response return inner def response_for_exception(request, exc): if isinstance(exc, Http404): if settings.DEBUG: response = debug.technical_404_response(request, exc) else: response = get_exception_response( request, get_resolver(get_urlconf()), 404, exc ) elif isinstance(exc, PermissionDenied): response = get_exception_response( request, get_resolver(get_urlconf()), 403, exc ) log_response( "Forbidden (Permission denied): %s", request.path, response=response, request=request, exception=exc, ) elif isinstance(exc, MultiPartParserError): response = get_exception_response( request, get_resolver(get_urlconf()), 400, exc ) log_response( "Bad request (Unable to parse request body): %s", request.path, response=response, request=request, exception=exc, ) elif isinstance(exc, BadRequest): if settings.DEBUG: response = debug.technical_500_response( request, *sys.exc_info(), status_code=400 ) else: response = get_exception_response( request, get_resolver(get_urlconf()), 400, exc ) log_response( "%s: %s", str(exc), request.path, response=response, request=request, exception=exc, ) elif isinstance(exc, SuspiciousOperation): if isinstance(exc, (RequestDataTooBig, TooManyFieldsSent, TooManyFilesSent)): # POST data can't be accessed again, otherwise the original # exception would be raised. request._mark_post_parse_error() # The request logger receives events for any problematic request # The security logger receives events for all SuspiciousOperations security_logger = logging.getLogger( "django.security.%s" % exc.__class__.__name__ ) security_logger.error( str(exc), exc_info=exc, extra={"status_code": 400, "request": request}, ) if settings.DEBUG: response = debug.technical_500_response( request, *sys.exc_info(), status_code=400 ) else: response = get_exception_response( request, get_resolver(get_urlconf()), 400, exc ) else: signals.got_request_exception.send(sender=None, request=request) response = handle_uncaught_exception( request, get_resolver(get_urlconf()), sys.exc_info() ) log_response( "%s: %s", response.reason_phrase, request.path, response=response, request=request, exception=exc, ) # Force a TemplateResponse to be rendered. if not getattr(response, "is_rendered", True) and callable( getattr(response, "render", None) ): response = response.render() return response def get_exception_response(request, resolver, status_code, exception): try: callback = resolver.resolve_error_handler(status_code) response = callback(request, exception=exception) except Exception: signals.got_request_exception.send(sender=None, request=request) response = handle_uncaught_exception(request, resolver, sys.exc_info()) return response def handle_uncaught_exception(request, resolver, exc_info): """ Processing for any otherwise uncaught exceptions (those that will generate HTTP 500 responses). """ if settings.DEBUG_PROPAGATE_EXCEPTIONS: raise if settings.DEBUG: return debug.technical_500_response(request, *exc_info) # Return an HttpResponse that displays a friendly error message. callback = resolver.resolve_error_handler(500) return callback(request)