Improve `RawHeaders` type hints (#14303)

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David Robertson 2022-10-28 17:04:02 +01:00 committed by GitHub
parent 81815e0561
commit 730b13dbc9
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3 changed files with 24 additions and 9 deletions

1
changelog.d/14303.misc Normal file
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@ -0,0 +1 @@
Improve type hinting of `RawHeaders`.

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@ -178,13 +178,13 @@ class KeyUploadServlet(RestServlet):
# Proxy headers from the original request, such as the auth headers
# (in case the access token is there) and the original IP /
# User-Agent of the request.
headers = {
header: request.requestHeaders.getRawHeaders(header, [])
headers: Dict[bytes, List[bytes]] = {
header: list(request.requestHeaders.getRawHeaders(header, []))
for header in (b"Authorization", b"User-Agent")
}
# Add the previous hop to the X-Forwarded-For header.
x_forwarded_for = request.requestHeaders.getRawHeaders(
b"X-Forwarded-For", []
x_forwarded_for = list(
request.requestHeaders.getRawHeaders(b"X-Forwarded-For", [])
)
# we use request.client here, since we want the previous hop, not the
# original client (as returned by request.getClientAddress()).

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@ -25,7 +25,6 @@ from typing import (
List,
Mapping,
Optional,
Sequence,
Tuple,
Union,
)
@ -90,14 +89,29 @@ incoming_responses_counter = Counter(
"synapse_http_client_responses", "", ["method", "code"]
)
# the type of the headers list, to be passed to the t.w.h.Headers.
# Actually we can mix str and bytes keys, but Mapping treats 'key' as invariant so
# we simplify.
# the type of the headers map, to be passed to the t.w.h.Headers.
#
# The actual type accepted by Twisted is
# Mapping[Union[str, bytes], Sequence[Union[str, bytes]] ,
# allowing us to mix and match str and bytes freely. However: any str is also a
# Sequence[str]; passing a header string value which is a
# standalone str is interpreted as a sequence of 1-codepoint strings. This is a disastrous footgun.
# We use a narrower value type (RawHeaderValue) to avoid this footgun.
#
# We also simplify the keys to be either all str or all bytes. This helps because
# Dict[K, V] is invariant in K (and indeed V).
RawHeaders = Union[Mapping[str, "RawHeaderValue"], Mapping[bytes, "RawHeaderValue"]]
# the value actually has to be a List, but List is invariant so we can't specify that
# the entries can either be Lists or bytes.
RawHeaderValue = Sequence[Union[str, bytes]]
RawHeaderValue = Union[
List[str],
List[bytes],
List[Union[str, bytes]],
Tuple[str, ...],
Tuple[bytes, ...],
Tuple[Union[str, bytes], ...],
]
def check_against_blacklist(