fix: strip connection-specific headers from HTTP/2 requests - #935
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lennartschoch wants to merge 1 commit into
Open
fix: strip connection-specific headers from HTTP/2 requests#935lennartschoch wants to merge 1 commit into
lennartschoch wants to merge 1 commit into
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RFC 9113 8.2.2 bans connection, keep-alive, proxy-connection, transfer-encoding and upgrade, and the h2 layer refuses to send a block containing one, so the request fails with protocol_error before it reaches the socket. They are legal in HTTP/1.1 and the caller cannot know which protocol ALPN picked, so drop them next to Host rather than failing requests that are valid for hackney's own API.
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Hit this moving an Elixir app onto hackney 4. As soon as ALPN picked h2, every request to one API started failing with
{error, protocol_error}and nothing reached the server.Turned out the client sets
Connection: keep-alivein its default headers, which is fine in HTTP/1.1 and banned in h2 (RFC 9113 §8.2.2). The h2 layer is doing the right thing here —validate_outbound_request/1rejects the header block and repliesprotocol_errorbefore anything is written. The problem is thatnormalize_headers/1only stripsHost, so the header gets that far in the first place.Since hackney picks the protocol itself via ALPN, the caller has no way to know which set of rules applies, so it can't really be the caller's job to leave these out.
Hostis already dropped there for the same kind of reason (:authoritycarries it), so this just extends it to the other five.TEis left alone since it's allowed with the valuetrailersand the h2 layer checks that separately.rebar3 eunitis green, 1099 tests. The three new ones intest/hackney_http2_connection_headers_tests.erlfail without the change with{error, protocol_error}— one forConnectionon its own, one for all five in mixed casing, and one checking ordinary headers still get through so the filter isn't over-eager.