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import re
from typing import TYPE_CHECKING, Awaitable, Callable, Tuple, Type, TypeVar
from .typedefs import Handler
from .web_exceptions import HTTPPermanentRedirect, _HTTPMove
from .web_request import Request
from .web_response import StreamResponse
from .web_urldispatcher import SystemRoute
__all__ = (
"middleware",
"normalize_path_middleware",
)
if TYPE_CHECKING: # pragma: no cover
from .web_app import Application
_Func = TypeVar("_Func")
async def _check_request_resolves(request: Request, path: str) -> Tuple[bool, Request]:
alt_request = request.clone(rel_url=path)
match_info = await request.app.router.resolve(alt_request)
alt_request._match_info = match_info
if match_info.http_exception is None:
return True, alt_request
return False, request
def middleware(f: _Func) -> _Func:
f.__middleware_version__ = 1 # type: ignore[attr-defined]
return f
_Middleware = Callable[[Request, Handler], Awaitable[StreamResponse]]
def normalize_path_middleware(
*,
append_slash: bool = True,
remove_slash: bool = False,
merge_slashes: bool = True,
redirect_class: Type[_HTTPMove] = HTTPPermanentRedirect,
) -> _Middleware:
"""Factory for producing a middleware that normalizes the path of a request.
Normalizing means:
- Add or remove a trailing slash to the path.
- Double slashes are replaced by one.
The middleware returns as soon as it finds a path that resolves
correctly. The order if both merge and append/remove are enabled is
1) merge slashes
2) append/remove slash
3) both merge slashes and append/remove slash.
If the path resolves with at least one of those conditions, it will
redirect to the new path.
Only one of `append_slash` and `remove_slash` can be enabled. If both
are `True` the factory will raise an assertion error
If `append_slash` is `True` the middleware will append a slash when
needed. If a resource is defined with trailing slash and the request
comes without it, it will append it automatically.
If `remove_slash` is `True`, `append_slash` must be `False`. When enabled
the middleware will remove trailing slashes and redirect if the resource
is defined
If merge_slashes is True, merge multiple consecutive slashes in the
path into one.
"""
correct_configuration = not (append_slash and remove_slash)
assert correct_configuration, "Cannot both remove and append slash"
@middleware
async def impl(request: Request, handler: Handler) -> StreamResponse:
if isinstance(request.match_info.route, SystemRoute):
paths_to_check = []
if "?" in request.raw_path:
path, query = request.raw_path.split("?", 1)
query = "?" + query
else:
query = ""
path = request.raw_path
if merge_slashes:
paths_to_check.append(re.sub("//+", "/", path))
if append_slash and not request.path.endswith("/"):
paths_to_check.append(path + "/")
if remove_slash and request.path.endswith("/"):
paths_to_check.append(path[:-1])
if merge_slashes and append_slash:
paths_to_check.append(re.sub("//+", "/", path + "/"))
if merge_slashes and remove_slash:
merged_slashes = re.sub("//+", "/", path)
paths_to_check.append(merged_slashes[:-1])
for path in paths_to_check:
path = re.sub("^//+", "/", path) # SECURITY: GHSA-v6wp-4m6f-gcjg
resolves, request = await _check_request_resolves(request, path)
if resolves:
raise redirect_class(request.raw_path + query)
return await handler(request)
return impl
def _fix_request_current_app(app: "Application") -> _Middleware:
@middleware
async def impl(request: Request, handler: Handler) -> StreamResponse:
with request.match_info.set_current_app(app):
return await handler(request)
return impl
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