[hippi345]

Motivation

HTTPKeepAliveHandler never read the inbound Connection header. A client that sends Connection: close (RFC 9112 §9.6) is stating that this is the last request on the connection, but the server kept the channel open until the idle or read-header timeout. The response also omitted Connection: close.

The first fix set closeAfterResponseEnd from the request head. That introduced a pipelining bug: HTTPServerPipelineHandler.write(.end) can synchronously deliver the next pending request, whose .head re-enters channelRead and overwrites closeAfterResponseEnd before the current response decides whether to close. Three pipelined POSTs with Connection: close only on the last request then produced r1 and r2 and EOF — r3 never went out, and r2 had no Connection: close. The header check also used == "close", so list forms such as keep-alive, close were ignored.

Fixes #119

HTTP/1.0 default close / keep-alive handling is intentionally out of scope to keep the change small and reduce conflicts with #94.

Modifications

• In HTTPKeepAliveHandler.channelRead, when any Connection field contains a close token, set closeAfterResponseEnd.
• Parse every Connection field: split on ,, trim whitespace, compare tokens case-insensitively.
• When streaming a fully received request, copy Connection: close onto the response head.
• Capture let shouldClose = self.closeAfterResponseEnd before context.write in the .streaming path, and capture the close decision before the writes in flushBuffer. Use that captured value for the Connection header and the close-after-.end decision so a pipelined next request cannot close the current response early.
• Tests in HTTPKeepAliveHandlerTests: single-request close (plaintext and TLS), EmbeddedChannel close, pipelined POSTs where only the last request has Connection: close (plaintext and TLS), and token forms (keep-alive, close, close, TE, Close, two separate Connection fields).

Result

A request with a close token receives Connection: close on the response, and the connection closes after that response ends. Earlier pipelined responses on the same connection stay keep-alive and are fully written.

Testing

Toolchain: Swift 6.4.1 (swift-6.4.1-RELEASE), x86_64-unknown-linux-gnu

Commands (CI-equivalent):

SWIFT_CERTIFICATES_ALLOW_SWIFT_CRYPTO_BETA=1 ENABLE_ALL_TRAITS=1 \
  swift test --explicit-target-dependency-import-check error -Xswiftc -require-explicit-sendable

swift-format lint --strict on the two changed files passed.

Before (unmodified main, new tests only)

All new tests failed at runtime:

✘ Test "Connection close token forms close the EmbeddedChannel after the response"
  connectionValue → "close" / "keep-alive, close" / "close, TE" / "Close"
  Expectation failed: response.headerFields[.connection] == "close"
  Expected Connection: close, got headers: [Content-Length: 0]
✘ Test testConnectionCloseAcrossMultipleConnectionFields()
  Expectation failed: response.headerFields[.connection] == "close"
✘ Test "Pipelined POSTs: only the last Connection: close closes after that response"
  http1Variant → .plaintextHTTP1_1 / .http1_1
  Expectation failed: response.headerFields[.connection] == "close"
  (r1–r3 arrived; r3 had no Connection: close; connection stayed open)
✘ Test run with 3 tests in 1 suite failed after 30.040 seconds with 12 issues.

Before (35416cd, new tests only)

The first fix honored a lone close / Close token, but missed list forms and broke pipelining:

✘ Test "Connection close token forms …" connectionValue → "keep-alive, close"
  Expectation failed: response.headerFields[.connection] == "close"
✘ Test "Connection close token forms …" connectionValue → "close, TE"
  Expectation failed: response.headerFields[.connection] == "close"
✘ Test testConnectionCloseAcrossMultipleConnectionFields()
  Expectation failed: response.headerFields[.connection] == "close"
✘ Test "Pipelined POSTs: only the last Connection: close closes after that response"
  Expected .head for request 3, got nil
✘ Test run with 3 tests in 1 suite failed after 0.032 seconds with 8 issues.

After (this change)

New tests:

✔ Test testConnectionCloseAcrossMultipleConnectionFields() passed after 0.003 seconds.
✔ Test "Connection close token forms close the EmbeddedChannel after the response" with 4 test cases passed after 0.003 seconds.
✔ Test testRequestConnectionCloseClosesEmbeddedChannelAfterResponseEnd() passed after 0.003 seconds.
✔ Test "Pipelined POSTs: only the last Connection: close closes after that response" with 2 test cases passed after 0.025 seconds.
✔ Test "Request Connection: close closes the connection after the response ends" with 2 test cases passed after 0.026 seconds.
✔ Test run with 5 tests in 1 suite passed after 0.026 seconds.

Full suite:

✔ Test run with 210 tests in 43 suites passed after 6.018 seconds.

This change was prepared with AI assistance and reviewed by the author.