Skip to content
This repository has been archived by the owner on Apr 26, 2024. It is now read-only.

Commit

Permalink
Improve type hinting of RawHeaders
Browse files Browse the repository at this point in the history
to detect the problem that #14301 fixed.
  • Loading branch information
David Robertson committed Oct 26, 2022
1 parent 3c0e76a commit 54d3de8
Show file tree
Hide file tree
Showing 2 changed files with 23 additions and 8 deletions.
8 changes: 4 additions & 4 deletions synapse/app/generic_worker.py
Original file line number Diff line number Diff line change
Expand Up @@ -178,14 +178,14 @@ async def on_POST(
# 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(
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()).
if isinstance(request.client, (address.IPv4Address, address.IPv6Address)):
Expand Down
23 changes: 19 additions & 4 deletions synapse/http/client.py
Original file line number Diff line number Diff line change
Expand Up @@ -90,14 +90,29 @@
"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(
Expand Down

0 comments on commit 54d3de8

Please sign in to comment.