elixir-mint / mint / 0e474d7cc54a4274629a259d0a8ce5dbe6765ff0-PR-479

88%

main: 88%

Pull #479

github

Fix HTTP/1 handling of 1xx informational responses

1xx informational responses (100 Continue, 103 Early Hints, etc.) were
treated the same as HEAD and 204/304 responses: Mint emitted `{:done, ref}`
and popped the request from its queue. The real final response arriving
afterwards had no active request and Mint returned `{:unexpected_data, _}`,
closing the connection.

This broke two common scenarios:

  * Requests sent with `Expect: 100-continue`, where the server sends 100
    Continue before the final response.
  * Servers or intermediaries emitting unsolicited 1xx (Plug.Conn.inform/3,
    HAProxy 102 Processing, CDNs sending 103 Early Hints, etc.).

Fix: split 1xx out of the `:none` body branch in `message_body/1` into a
new `:informational` body kind. In `decode_body/5`, the `:informational`
clause resets the request's response-side fields (`version`, `status`,
`headers_buffer`, etc.) back to their initial state and continues parsing
from `:status` without popping the request. The `{:status, ref, 1xx}` and
`{:headers, ref, _}` responses are still emitted to the caller by the
existing `:status`/`:headers` decode stages, so informational responses
remain visible; only the premature `{:done, ref}` is suppressed.

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