fix: retry close_notify in poll_shutdown when the send buffer is full - #78
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fix: retry close_notify in poll_shutdown when the send buffer is full#78ArniDagur wants to merge 1 commit into
close_notify in poll_shutdown when the send buffer is full#78ArniDagur wants to merge 1 commit into
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`poll_shutdown` marked the write side closed _before_ enforcing a successful `close_notify`. With a full send buffer this resulted in two bugs: 1. Shutdown failed with `WouldBlock`, which is an error type that should not escape a poll-based API. 2. Subsequent retries of the shutdown skipped the `close_notify` entirely, since `write_closed` was already set. We fix this by only marking the write side closed once the alert is sent (or has failed fatally), and retrying on `WouldBlock`. The retry uses a new `AsyncWriteReady` trait, which mirrors the preexisting `AsyncReadReady`. It exposes tokio's `poll_write_ready` and `try_io`. The latter `try_write_io` clears write-readiness when `send_close_notify` returns `WouldBlock`, so the task parks until the socket becomes writable instead of [busy-polling][1]. [1]: https://github.com/rustls/ktls/blob/5e3c7d6ceadbb1ae98d06908d559490723899aed/ktls/src/ktls_stream.rs#L268-L277 This PR introduces a minor breaking change, since the `AsyncWrite` impl for `KtlsStream<IO>` now requires `IO: AsyncWriteReady`. This change also lays the foundation for additional work, including in relation to properly implementing `KeyUpdate`.
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poll_shutdownmarked the write side closed before enforcing a successfulclose_notify. With a full send buffer this resulted in two bugs:WouldBlock, which is an error type that should not escape a poll-based API.close_notifyentirely, sincewrite_closedwas already set.We fix this by only marking the write side closed once the alert is sent (or has failed fatally), and retrying on
WouldBlock.The retry uses a new
AsyncWriteReadytrait, which mirrors the preexistingAsyncReadReady. It exposes tokio'spoll_write_readyandtry_io. The latter clears write-readiness whensend_close_notifyreturnsWouldBlock, so the task parks until the socket becomes writable instead of busy-polling.This PR introduces a minor breaking change, since the
AsyncWriteimpl forKtlsStream<IO>now requiresIO: AsyncWriteReady. This change also lays the foundation for additional work, including in relation to properly implementingKeyUpdate(which I plan on doing).