tls: close the connection when a post-handshake SSL_write fails instead of leaving it open by robobun · Pull Request #38176 · oven-sh/bun

robobun · 2026-08-13T11:14:50Z

Problem

When SSL_write fails with a fatal error on a TLS socket whose handshake has already completed, the connection is left open and silent: no 'error' or 'close' reaches JS, socket.write() keeps reporting success (the data is buffered forever), and Bun.serve / fetch / node:tls peers waiting for our bytes hang until the peer itself gives up.
us_internal_ssl_write (packages/bun-usockets/src/crypto/openssl.c) marks the socket fatal (ssl_park_fatal_reason) and returns 0, which every caller (node:tls and Bun sockets through socket_body.rs, uWS AsyncSocket, the fetch client) reads as backpressure: buffer and wait for a writable event.
Nothing ever closes the socket afterwards: us_internal_ssl_on_writable returned early for fatal sockets, us_internal_ssl_is_shut_down() becomes true so end() / shutdown() are no-ops, the read side only notices when the peer happens to send more bytes, and once the handshake has been reported there is no handshake dispatch left to carry the failure. The same applies to the two batching allocation failures that set ssl_fatal_error from inside the write BIO.
Observed through tls: send a post-handshake ticket flight larger than 64 KiB #38120's record-layer bug (TLSv1.3 requestCert server, client chain of ~48 KiB: the first SSL_write after the handshake fails with ERR_R_INTERNAL_ERROR). That PR fixes the trigger; this one fixes what the socket layer does when any post-handshake write fails fatally.

Fix

us_internal_ssl_write: every fatal exit now arms writable interest (last_write_failed + us_internal_rearm_writable, which socket.c now exports) before returning 0.
us_internal_ssl_on_writable closes fatal sockets (ssl_close(s, 0, NULL), the same close the data path performs for a fatal SSL_read) at two points:
- on entry, before the spill drain: this is the event armed above, and it also covers a handshake that failed while being driven from the writable event, which previously dispatched the failure and then left the dead socket open (the data-path driver already closes in that case);
- after us_dispatch_writable returns: loop.c drops writable interest from a shut-down socket as soon as the writable dispatch returns (us_socket_is_shut_down includes ssl_fatal_error), so a consumer that hits the failure from its own writable handler (uWS draining a backpressured response) would otherwise never get another event. The existing spill-death branch goes through the same epilogue, so it still dispatches writable first exactly as before and now also closes a consumer that did not close itself.
The close is deferred to the writable dispatch instead of performed inside the write because on_close tears down per-socket state underneath the caller (uWS destroys its HttpResponseData in on_close while AsyncSocket::write is still on the stack); deferring to a dispatch boundary is the pattern ssl_close_after_spill already uses. With ssl_fatal_error set, us_internal_ssl_close never defers again (the spill deferral and ssl_handle_shutdown both short-circuit on it), so the armed event cannot spin.
Before the handshake has been reported, that close runs ssl_update_handshake, which dispatches the reason the write parked (ssl_dispatch_parked_reason): the same EPROTO report the peer's hang-up used to trigger, just without depending on the peer.
us_socket_write_check_error (socket.c): a TLS write that made the socket fatal after the handshake was reported now returns EPROTO through fatal_write_error, the channel plain TCP already uses for peer-gone sends. node:tls and Bun sockets therefore take their existing failed-write path: write callback gets the error, 'error' (code: "EPROTO", syscall: "write"), then 'close'; the flush retried from the writable dispatch reports through the same channel. EPROTO is the code node uses for SSL-level write failures (TLSWrap::ClearIn → UV_EPROTO). Failures before the handshake is reported keep their existing channel (the handshake dispatch carries the real reason), hence the us_internal_ssl_handshake_callback_has_fired guard. On Windows the branch reports -UV_EPROTO instead of UCRT's EPROTO: the errno table there only names libuv-synthetic codes, so the UCRT value would have been reshaped as ECONNRESET by failWrite; with the libuv value the user-visible code is EPROTO on every platform, matching Node.
This second part is not cosmetic: with only the usockets close, node:tls receives a plain close while a write is parked and never fails it, so the JS socket still never reaches 'close' (see the ablation below; the underlying net.ts gap is pre-existing and reported separately).
us_internal_ssl_write now clears the OpenSSL error queue before writing, like the read and handshake drivers already do: SSL_get_error peeks the per-thread queue, so an entry left there by another socket would have classified a plain WANT_READ as fatal (previously a silently dead socket, now a visible close).
us_internal_ssl_write seals a large write one 16 KiB record at a time, and it classified the failing SSL_write only when no record had gone through yet. A WANT_READ or fatal error on a later record came back as a plain partial write: the socket was neither marked fatal nor armed for writable, so the remainder the caller buffered never moved. The epilogue now classifies last_ssl_written <= 0 whatever total is (from review).
Test infrastructure: a new ssl_write fault-injection point in us_internal_ssl_write fails an SSL_write the way a record-layer failure does (-1 plus ERR_R_INTERNAL_ERROR on the error queue, so SSL_get_error genuinely reports SSL_ERROR_SSL and everything downstream runs unmodified). It checks once per SSL_write call, so a rule's after count can target a later record of one write. Wired through fault_inject.h, uws_sys/lib.rs, the socketFaultInjection.set() name list and its type.
Verified:
- test/js/node/tls/tls-syscall-fault.test.ts, "fatal SSL_write after the handshake": node:tls direct write (EPROTO callback + 'error' + 'close', peer sees the connection go away), node:tls write whose second record fails (same outcome, client receives exactly the first 16384 bytes; with the old epilogue it times out with the remainder buffered), node:tls flush retried from the writable dispatch, Bun.serve + fetch immediate response (rejects instead of hanging), Bun.serve backpressured response (failure inside the writable dispatch).
- test/js/node/tls/node-tls-server.test.ts, "completes a write that fails inside the TLS layer after the handshake": the real tls: send a post-handshake ticket flight larger than 64 KiB #38120 scenario on current main. Times out on the released binary, passes with this change (write callback gets EPROTO, 'error', 'close'); written so it keeps passing once tls: send a post-handshake ticket flight larger than 64 KiB #38120 lands (the write then succeeds and the reply must arrive).
- test/js/bun/util/socket-fault-injection.test.ts: the new name is accepted with errno (with or without fd) and rejected for short / zero.
- Windows (x64 debug build of this branch): the tls: send a post-handshake ticket flight larger than 64 KiB #38120 scenario wedges on the released binary there too; with this change the write callback, 'error' (code: "EPROTO") and 'close' all fire, and the full node-tls-server.test.ts file passes (71 tests).
- test/js/node/tls/ in full: 245 pass; the 2 failures (SNICallback ... bind hostname, already tracked as a localhost dual-stack test issue, and the 16-worker root-cert init test) fail identically without this change in this container and involve no TLS writes.
- Fault-injection suites for fetch, Bun.serve, node:http, node:http2, node:net, Bun sockets, WebSocket and ws: all pass (four tests need more than the 5 s default under this debug build; they pass with a longer timeout and three of them use no TLS at all).
- test/js/bun/net/: the 13 failures are the pre-existing localhost ECONNREFUSED set (identical with the released binary); the TLS tests pass.

Background

usockets TLS layer: openssl.c wraps each us_socket_t that has s->ssl. loop.c routes readable events to us_internal_ssl_on_data (which runs SSL_read and dispatches plaintext) and writable events to us_internal_ssl_on_writable (which drains pending ciphertext and then dispatches the consumer's writable handler). us_socket_write on a TLS socket is us_internal_ssl_write, which runs SSL_write and sends the sealed records; its return value is "plaintext bytes accepted", and 0 means "nothing accepted, write again on the next writable event".
ssl_fatal_error: per-socket bit meaning the SSL state is unusable. us_internal_ssl_is_shut_down (and so us_socket_is_shut_down) returns true for it, writes are refused, and us_internal_ssl_on_data closes the socket on the next incoming bytes. Until now nothing closed it proactively.
Parked reason: when an SSL call fails before the handshake has been reported, ssl_park_fatal_reason stores the OpenSSL error string per loop so the handshake-failure dispatch can report it (EPROTO plus the reason) instead of a bare verify verdict. Once the handshake has been reported there is no consumer for it.
Spill: ciphertext from a partially sent batch that SSL already counts as written; it is drained from the owner's writable events, and graceful closes defer until it is gone. A fatal socket skips that deferral and ssl_release_spill makes one last attempt to send it.
us_socket_write_check_error / fatal_write_error: the write entry point socket_body.rs uses. For plain TCP it classifies send errnos and reports peer-gone ones through the out-parameter; write_maybe_corked turns that into a negative errno for JS (net.ts failWrite) and internal_flush / on_writable into an 'error' followed by a close. Until now the TLS branch never set it.
Fault injection: LIBUS_SOCKET_FAULT_INJECTION (on in ASan builds) compiles US_FAULT_CHECK hooks that tests arm through bun:internal-for-testing's socketFaultInjection; besides the syscall hooks it already has a few non-syscall points for failure paths that are unreachable otherwise (ssl_loop_buffer, poll_start, session_buffer). ssl_write is one more of those.

Ablations (each variant rebuilt and run against the new tests)

Usockets close removed, EPROTO report kept: both node:tls tests pass, both Bun.serve tests time out.
Only the post-dispatch close in us_internal_ssl_on_writable removed: only the backpressured Bun.serve test times out (the loop stripped writable interest after the dispatch).
EPROTO report removed, usockets close kept: both node:tls tests and the tls: send a post-handshake ticket flight larger than 64 KiB #38120-scenario test time out. The transport closes, but node:tls receives a plain close with a write parked, emits 'end' and never fails the write, so 'close' never follows.

Repro on the released binary (1.4.0), #38120 scenario

Server writes a reply from its 'data' handler:

write() returned true
TIMEOUT: server socket still open after 2s

With this change:

write() returned true
write cb EPROTO
server error EPROTO write write EPROTO
server close hadError=true

(write() returning true is node's behavior too: a 4-byte chunk is below the highWaterMark and the failure is delivered through the callback and 'error'.)

no test proof · iteration 3 · platform-specific test(s) that do not run on this machine, deferring to CI, which covers all platforms: test/js/node/tls/tls-syscall-fault.test.ts, test/js/node/tls/node-tls-server.test.ts

…it as a failed write A fatal SSL_write error (SSL_ERROR_SSL / SSL_ERROR_SYSCALL, or the batching allocation failures that mark the socket fatal from inside the BIO) left us_internal_ssl_write returning 0, which every caller reads as backpressure. Nothing closed the socket afterwards: us_internal_ssl_on_writable returned early for fatal sockets, the read side only notices when the peer sends more, and once the handshake has been reported there is no handshake dispatch to carry the failure. The connection stayed open with the data buffered forever. us_internal_ssl_write now arms writable interest after marking the socket fatal, and us_internal_ssl_on_writable closes fatal sockets: on entry (the event armed by the write, or a handshake that failed while being driven from the writable event) and again after dispatching to the consumer, because the loop drops writable interest from a shut-down socket as soon as that dispatch returns, so a consumer that hits the failure from its own writable handler would otherwise get no further event. Closing is deferred rather than done inside the write because on_close tears down per-socket state underneath the caller (uWS destroys its HttpResponseData there). Before the handshake has been reported, the close dispatches the reason parked by the write, the same report the peer's hang-up used to trigger. us_socket_write_check_error reports EPROTO for a TLS write that made the socket fatal after the handshake was reported, so node:tls and Bun sockets take their existing failed-write path (callback(err), 'error', 'close'), like a peer-gone send on plain TCP. Without it node:tls would park the write and wait for a drain that never comes even after the transport is closed. The write driver also starts from a clean error queue like the read and handshake drivers, so a stale entry from another socket cannot make a WANT_READ look fatal. A new "ssl_write" fault-injection point fails the next SSL_write the way a record-layer failure does, so the path has a permanent test; the scenario from the record-layer bug that exposed it (TLSv1.3 requestCert with a ~48 KiB client chain) is covered as well.

coderabbitai · 2026-08-13T11:15:00Z

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Walkthrough

The change adds fatal SSL_write fault injection, reports post-handshake failures as EPROTO, rearms writable polling, and closes affected TLS sockets through writable processing. New tests cover direct writes, buffered writes, Bun.serve, and validation rules.

Changes

TLS write failure handling

Layer / File(s)	Summary
Fatal SSL write path `packages/bun-usockets/src/crypto/openssl.c`, `packages/bun-usockets/src/internal/internal.h`, `packages/bun-usockets/src/socket.c`	Fatal post-handshake SSL write failures are classified, reported as `EPROTO`, and routed through writable processing for socket closure.
SSL write fault injection `packages/bun-usockets/src/internal/fault_inject.h`, `src/uws_sys/lib.rs`, `src/js/internal-for-testing.ts`, `src/runtime/socket/socket_body.rs`, `src/uws_sys/socket.rs`	The `ssl_write` fault-injection target is exposed through native, Rust, JavaScript, and socket validation interfaces.
TLS regression coverage `test/js/node/tls/node-tls-server.test.ts`, `test/js/node/tls/tls-syscall-fault.test.ts`, `test/js/bun/util/socket-fault-injection.test.ts`	Tests cover fatal direct writes, writable-dispatch retries, `Bun.serve` responses, connection closure, and accepted or rejected fault-injection rules.

Suggested reviewers: cirospaciari

Priority: ⬆️ High

Merge Risk: ⚪ Minimal · up to f6711

Fatal TLS write failures now report errors and close affected connections, with regression coverage for direct, buffered, and server response writes.

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

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Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly and concisely states the main change: closing TLS connections after post-handshake SSL_write failures.
Description check	✅ Passed	The description is detailed and covers the problem, implementation, verification steps, test results, and platform-specific behavior. It does not use the exact template headings, but it provides the r…

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robobun · 2026-08-13T11:15:13Z

Status: reproduced on the released binary with the #38120 scenario (TLSv1.3 requestCert server, ~48 KiB client chain): the server's write() returns true and the socket then stays open with no error, close or write callback. With this branch the same run fails the write with EPROTO and closes the socket; the permanent coverage uses the new ssl_write fault point in test/js/node/tls/tls-syscall-fault.test.ts. Details and the ablation results are in the PR description.

… rejection

…ndows

github-actions · 2026-08-13T11:29:40Z

Found 1 issue this PR may fix:

HTTPS requests hanging (regression 1.2.23 -> 1.3.x) #26066 - HTTPS requests that were flowing normally suddenly hang forever with no response, no error, and no close — the same user-visible shape as a fatal post-handshake SSL_write leaving the socket open and silent (symptom match; root cause unproven, but this PR would at minimum turn the silent hang into an EPROTO error + 'close').

If this is helpful, copy the block below into the PR description to auto-close these issues on merge.

Fixes #26066

🤖 Generated with Claude Code

…ames as EPROTO

robobun · 2026-08-13T17:55:27Z

Not adding a Fixes line for #26066: the symptom matches (requests hang with no error) but that issue has no proven root cause, so auto-closing it on merge would be premature. This change does turn a fatal post-handshake SSL_write into an EPROTO error plus close instead of a silent hang, so that repro is worth retesting once this lands.

claude

I re-reviewed after 4f8947b and found no bugs — the Windows -UV_EPROTO fix and the two stale-comment updates from my earlier feedback are all in place. Because this reworks the usockets TLS writable-dispatch / close ordering and the cross-FFI error-propagation contract, a human look at the us_internal_ssl_on_writable changes and the ssl_close_if_fatal placement would still be worthwhile.

What was reviewed:

us_internal_ssl_write fatal path: rearm-writable + ERR_clear_error addition; checked that ssl_fatal_error set before entry still short-circuits via us_socket_is_shut_down.
ssl_close_if_fatal at both entry and post-us_dispatch_writable sites; verified ssl_gone/null guards match the existing pattern.
us_socket_write_check_error TLS branch: Windows -UV_EPROTO gate now matches the plain-TCP branch's namespace convention.
Fault-injection wiring (SSL_WRITE = 13) is consistent across fault_inject.h, uws_sys/lib.rs, socket_body.rs, and the JS type.

Extended reasoning...

Overview

This PR fixes a hang when SSL_write fails fatally after the TLS handshake completes: the socket was previously left open and silent (write returns 0 → callers buffer forever). The fix arms a writable event from us_internal_ssl_write on fatal failure, closes fatal sockets from us_internal_ssl_on_writable (both on entry and after the consumer's writable dispatch returns), and reports EPROTO through us_socket_write_check_error's fatal_write_error out-parameter so node:tls / Bun sockets fail the write instead of buffering it. A new ssl_write fault-injection point makes the path testable. Files touched: packages/bun-usockets/src/crypto/openssl.c, socket.c, internal.h, fault_inject.h, plus Rust FFI mirrors and four test files.

Security risks

None identified. The change is error-path handling for an already-fatal TLS state; it does not weaken any verification, add user-controllable input parsing, or touch credential/certificate handling. The added ERR_clear_error() before SSL_write is a defensive correctness fix (prevents a stale error-queue entry from another socket misclassifying WANT_READ as fatal), not a security gate.

Level of scrutiny

High. This is core usockets TLS event-loop code: us_internal_ssl_on_writable is on every TLS socket's writable path, and the change inserts close calls at three points in that function plus reorders the us_internal_ssl_write epilogue. The deferred-close design (arm writable → close from the dispatch, not inline under the caller's write) is well-reasoned in the PR description and matches the existing ssl_close_after_spill pattern, but the interaction between the spill drain, the handshake-driven-from-writable case, and the post-us_dispatch_writable epilogue is subtle enough that a maintainer familiar with the loop's writable-interest lifecycle should confirm the placement.

Other factors

My earlier review flagged (1) the Windows UCRT EPROTO vs libuv-namespace mismatch and (2) two stale doc comments describing the pre-PR contract. Both were fixed in 4f8947b: the TLS branch now emits -UV_EPROTO on Windows (matching Node), and the write_check_error doc / BYPASS_TLS comment were updated. The node-tls-server test now asserts EPROTO unconditionally with no Windows branch.
Test coverage is thorough: four new fault-injection tests (node:tls direct + retried flush, Bun.serve immediate + backpressured), a real-scenario test in node-tls-server.test.ts written to keep passing after #38120 lands, and control-surface tests for the new hook. The PR description includes ablations proving each half of the fix is load-bearing.
The us_internal_rearm_writable export (was static) and the new us_internal_ssl_handshake_callback_has_fired guard are straightforward and match existing internal.h patterns.
No CODEOWNERS file gates these paths in this repo.

robobun · 2026-08-13T20:06:52Z

^{Updated 12:18 AM PT - Sep 11th, 2026}

✅ @robobun, your commit f671185c96f1dbba4de11e97e78282a29e59eb77 passed in Build #114164! 🎉

🧪 To try this PR locally:

bunx bun-pr 38176

That installs a local version of the PR into your bun-38176 executable, so you can run:

bun-38176 --bun

cirospaciari · 2026-09-10T20:08:58Z

@robobun please run the tests this PR adds or changes on Node.js v26.3.0 and report whether each one passes or fails.
They must pass on both Bun and Node v26.3.0, so fix any case that only passes on Bun.

robobun · 2026-09-10T20:19:51Z

Ran the tests this PR adds or changes against Node v26.3.0 (linux x64). Results per test:

test/js/node/tls/node-tls-server.test.ts, "completes a write that fails inside the TLS layer after the handshake instead of leaving the socket open" (the only new test that uses public node:tls API)

Node v26.3.0: pass, 5 of 5 runs. Ported the test body verbatim to node --test with the same fixtures. Node takes the success branch: the 48 KiB client chain does not trip its record layer, so the pong reply arrives and the client closes cleanly.
Bun (this branch, debug build): pass. Bun takes the error branch: the write callback gets EPROTO, then 'error' and 'close'. The test allows both outcomes, since the contract it checks is that the write completes one way or the other and the connection ends.
Bun 1.4.0 (released): fail, times out at 5 s with the server socket still open.

test/js/node/tls/tls-syscall-fault.test.ts, the four tests in "fatal SSL_write after the handshake"

Not runnable on Node: they arm Bun's ssl_write fault-injection hook through bun:internal-for-testing to make SSL_write fail on demand, and two of them use Bun.serve and fetch with tls. Node has no equivalent hook. The whole file is already describe.skipIf on the hook being compiled out.
Bun (this branch): 16 of 16 pass.

test/js/bun/util/socket-fault-injection.test.ts, "set() accepts ssl_write with action 'errno', with or without an fd" plus the two extended rejection lists

Not runnable on Node: this file tests the socketFaultInjection control surface itself.
Bun (this branch): 17 pass, 2 skip (the compiled-out cases).

No test passes only on Bun, so nothing needed a fix.

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Actionable comments posted: 1

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Inline comments:
In `@packages/bun-usockets/src/crypto/openssl.c`:
- Line 2896: Update the SSL write loop around the final SSL_write result so
last_ssl_written <= 0 is classified with SSL_get_error before returning partial
total. Preserve total as consumed bytes while still invoking
ssl_write_wants_read, ssl_park_fatal_reason, or writable rearming as
appropriate, and add coverage for a second-chunk failure in one multi-chunk
write.

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packages/bun-usockets/src/crypto/openssl.c
packages/bun-usockets/src/internal/fault_inject.h
packages/bun-usockets/src/internal/internal.h
packages/bun-usockets/src/socket.c
src/js/internal-for-testing.ts
src/runtime/socket/socket_body.rs
src/uws_sys/lib.rs
src/uws_sys/socket.rs
test/js/bun/util/socket-fault-injection.test.ts
test/js/node/tls/node-tls-server.test.ts
test/js/node/tls/tls-syscall-fault.test.ts

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…m main

…lti-chunk write A fatal error or WANT_READ on the second or later 16 KiB record came back as a plain partial write. The socket was neither marked fatal nor armed for writable, so the remainder the caller buffered never moved. Classify the failing chunk regardless of how many went through before it. The ssl_write fault hook now runs once per SSL_write call so a rule's after count can target a later chunk.

claude

Code review found no issues

No high-confidence issues detected in this change.

… parked (#43698) ### Problem - An accepted `node:tls` socket whose write is the first to see the peer's RST emits `'end'` and nothing else: no write callback, no `'error'`, no `'close'`. The server counts it forever, so `server.close()` never completes. On main, 16 of 30 connections end this way. Node: 0 of 30. - The last block of `SocketEmitEndNT` (`src/js/node/net.ts:875`) fails a parked write only when the native close carries an error or the socket is destroyed. Here the failed `send()` consumed the socket error, so the close carries none. ### Fix - A half-open `'end'` runs the same function, and its write can still drain. Tell the two apart by `kclosed`, which only the native close handlers set. A parked write on a closed handle fails with `ERR_SOCKET_CLOSED`, as the client-side close handler already does. `'error'` and `'close'` follow. - #42336 fixes the cause in the TLS write path, and alone it also removes this state (0 of 30, measured). #38176 alone does not (18 and 26 of 30). This change is the JS-side guarantee for any clean close that leaves a write parked. - Verified: new test in `test/js/node/tls/node-tls-server.test.ts` (fails on main with `events: []` and 2 connections, passes here). `test/js/node/tls/`, `test/js/node/net/` and Node's 325 `test-net-*`/`test-tls-*` files: same failures as main. ### Background - A write the kernel does not take whole is parked: the native socket buffers the rest, and `net.ts` keeps the callback in `kwriteCallback` until the drain. - Accepted sockets are half-open natively, so a peer FIN dispatches only `'end'`. - After a native close the fd is gone, and nothing parked can drain. <details><summary>Notes</summary> #### The ledger's repro (30 connections, the peer resets on the first byte of a 1 MiB write, node peer, linux-x64) | build | never closed | the other connections | |---|---|---| | node v26.3.0 | 0 of 30 | `error:ECONNRESET`, `close:true` | | main (release 367d939) | 16 of 30 (8 to 25 over other runs) | `error:ECONNRESET`, `close:true` | | main + #38176 | 18 and 26 of 30 | same | | main + #42336 | 0 and 0 of 30 | `cb:ECONNRESET`, `error:ECONNRESET`, `close:true` | | this branch | 0 of 30 | 16 took `end`, `cb:ERR_SOCKET_CLOSED`, `error:ERR_SOCKET_CLOSED`, `close:true` | For the two PR rows I merged each PR's head into main @a2b69f7b. #38176 merges cleanly. #42336 conflicts in two test files only, which I resolved to main's side. `src/` and `packages/` merged without conflicts. #### Mechanism, traced with the `Socket` debug scope ``` [socket] write(1048576) = 393216 the write takes many send() calls; one of them meets the RST [socket] onEnd S recv() returns 0: the failed send() consumed the error [socket] onClose S hangup, close code 0 ``` The TLS write path folds a rejected `send()` to "wire blocked" and keeps no errno (that is #42336). A plain `net.createServer` does not reach this state, because `us_socket_write_check_error` reports the errno and `failWrite` fails the write. #### What still differs from Node after this change The sockets that took this path report `'end'`, then `ERR_SOCKET_CLOSED`. Node reports `write ECONNRESET` and no `'end'`. The errno is gone by the time the close reaches JS, so only the native fix can restore it. With #42336 the write fails at write time and nothing is parked at the close, so the two changes do not overlap. If #42336 lands first, the new test here passes without this change, and this becomes a guard with no known trigger on Linux. #### The test The server runs in a child process so that it can stop polling. It reports the accepted socket, then blocks in `fs.readSync(0)` until the test has reset the connection, and only then writes. The write is therefore the first operation to see the reset on every run, with no timing involved: ``` node v26.3.0: write()=false | cb:ECONNRESET | error:ECONNRESET | close:true connections 0 main: write()=false | end (nothing more, 3 of 3) this branch: write()=false | end | cb:ERR_SOCKET_CLOSED | error:ERR_SOCKET_CLOSED | close:true connections 0 ``` A socket that never closes gives no event to wait for, so the server reports when a second connection arrives. That handshake takes several turns of the server's loop, and the reset socket closes in the first of them or not at all. The server then destroys both sockets, so the child exits in both outcomes and the test fails with the recorded state, not with a timeout (about 2 s on a debug build of main). The test asserts what holds in Node and on every platform: `'error'`, then `'close'` with `hadError` true, then a `getConnections()` of 1, which is the second connection. It also asserts that the child exited on its own. It does not pin the error code or the write callback. On main the read-error path never calls a parked write's callback, which is #43250. If the reset were seen by a read first, a fixed build would still pass. #### Overlap with open PRs #43392 rewrites the same block into a helper and keeps the same `destroyed || _err` condition, so it does not cover this case. The two conflict textually in that one hunk. The resolution is to keep its helper and call it when `kclosed` is set. </details>  --- **no test proof** · iteration 4 · platform-specific test(s) that do not run on this machine, deferring to CI, which covers all platforms: test/js/node/tls/node-tls-server.test.ts

robobun · 2026-09-22T23:29:35Z

A note on the per-write cost measured for this PR (about 800 more instructions per TLS round trip on small writes).

The ERR_clear_error() added before the SSL_write loop in us_internal_ssl_write repeats work that SSL_write already does. SSL_write starts with ssl_reset_error_state(), which calls ERR_clear_error() (ssl/ssl_lib.cc:950-952 and ssl/ssl_lib.cc:75-81 at the pinned BoringSSL). us_internal_ssl_write returns early for length == 0, so an SSL_write always follows the added clear. Nothing between the last SSL_write and SSL_get_error touches the error queue. An entry that another socket left on the queue cannot reach the classification.

Each ERR_clear_error() frees and zeroes all 16 queue slots (crypto/err/err.cc:266-281), about 400 instructions. Two TLS writes per round trip give the measured number.

The only path that skips SSL_write is the US_FAULT_SSL_WRITE branch. If the injected error needs a clean queue, the clear can move inside that #if block, before ERR_put_error. Production builds then pay nothing.

This comes from reading the source. It is not measured.

Jarred-Sumner · 2026-10-06T06:18:32Z

Superseded by #44618, which consolidates the open TLS pull requests. This fix and its tests are in there, either as written, rewritten smaller, or merged with the other PRs that patched the same cause (see the "By area" list in that PR). Closing in favor of it.

…essure (#34510, #38176, #42336) Every failed TLS write came back as "0 bytes, wait for writable": - send() rejected (EPIPE, ECONNRESET, ...): us_socket_raw_write folded -1 to 0 and re-armed writable. The kernel kept reporting writable, so the loop spun at 100% CPU (#24845), and a real reset ended as a clean close with the lost write reported as done. - SSL_write failed, or sealed records were lost to an allocation failure: the socket was marked fatal and nothing ever closed it. - SSL_write failed on a later 16 KiB record of one write: a plain partial write. A rejected send() of sealed records now ends the write side (the state our own FIN already has, so the BIO and the batch flush drop what can no longer leave) and asks for one writable event. There, outside any caller's write, the socket closes with an error, unless the peer's earlier bytes are still queued: then the read side delivers them first (a 413 sent before the server reset an upload). A fatal socket is closed at the same boundary. us_socket_write_check_error reports both: the errno of the send, or EPROTO, so node:tls fails the write like Node and Bun.connect's write()/end() return the documented -1. No new per-socket state: one int of loop scratch carries the errno from the raw send to the write that is still on the stack.

…ps, WebSocket, SQL) (#44618) ### What does this PR do? Consolidates the open TLS pull requests into one. Each was reproduced on `main` and, for `node:*` behavior, on Node v26.3.0 first. About a third are ported as written, the rest are rewritten smaller or merged into one fix where several PRs patched the same cause. One commit per fix, so it can be read commit by commit. Fixes #43520, fixes #31396, fixes #43635, fixes #37193, fixes #43846, fixes #17932, fixes #41061, fixes #36887, fixes #31810, fixes #35240, fixes #32234, fixes #44365, fixes #43807, fixes #42280, fixes #44517. Addresses #41856 (SNI and `servername`; not `checkServerIdentity` for SQL), #24845 (the spin is gone, shown with fault injection on Linux; not run on macOS), #19754 (node-fetch forwards the agent's TLS options; the Kubernetes client itself was not run). #### The ones that matter most | | On `main` | PRs | |---|---|---| | Client certificate disclosure | `https.request()` with a client certificate sends it to a server it then refuses (wrong name, `checkServerIdentity`, `destroy()` in `'secureConnect'`, `terminate()` in `handshake`). A server can force it with a junk record behind its Finished | #43946 | | False `authorized` | Over a Duplex, `secureConnect` with `authorized === true` for a peer that failed the key proof; `secureConnect` for a plaintext peer with `rejectUnauthorized: false` | #44422, #32929 | | Cleartext https | `https.createServer()` without a usable key/cert answers plain HTTP | #41672, #33539 | | Revoked client certificates | An https mTLS server never sees `crl`, so a revoked client is `authorized` | #41641 | | Pooled sockets | Requests with different client certificates or CAs share an `https.Agent` socket and session | #42498 | | Silent plaintext | `tls: [...]` given to `Bun.listen` / `Bun.connect` is plain TCP | #41490 | | Server weakened by a client knob | `NODE_TLS_REJECT_UNAUTHORIZED=0` turns off a server's client-certificate enforcement | #35245 | | Pins never checked | `WebSocket` never calls `tls.checkServerIdentity` and ignores `tls.serverName` | #41648 | | `verify-full` dropped | `PGSSLMODE=verify-*` is lost next to a `TLS_*` URL variable; `tls: true` sends no SNI | #44498 | | Crashes | use-after-free from `destroy()` in `ALPNCallback` over a Duplex; `abort()` on a late `setSession()`; SIGABRT in `fetch` with an https proxy from the environment and a `Bun.file()` body | #44462, #41671, #44458 | | Stream corruption | A TLS `write()` can lose 16 KiB it reported as written while another socket on the loop is stalled | #44529 | | Hangs and spins | 100% CPU on a failing `send()`; a fatal `SSL_write` leaves the socket open forever; `idleTimeout` never sheds a TLS client that ignores `close_notify` | #34510, #38176, #42336 | | Wrong certificate (regression since 1.3.14) | Connections accepted before `stop()` / `close()` get the default certificate and skip their entry's `requestCert` / `ca` | #42355 | | Quadratic Duplex / proxy tunnel | Reading one chunk over a Duplex, CPU: 8 MB 0.88 s → 0.14 s, 16 MB 3.18 s → 0.23 s, 32 MB 11.75 s → 0.39 s; `fetch` upload through CONNECT: 1.7 s → 0.18 s (debug build) | #44464 | #### By area - **fd engine, write path** (`openssl.c`, `socket.c`): #42352, #34510 + #38176 + #42336 as one change, #44529, #44458, #44192. A rejected `send()` ends the write side only and closes at the next writable event unless the peer's bytes are still queued (a 413 sent before a reset is still read). No new per-socket state. Also, on kqueue, **a FIN no longer ends a socket that waits in the low-priority queue** (`loop.c`): with more than 5 TLS handshakes at once, a client that ended right after its handshake could be reset and its server socket report `socket hang up`, because the eof that the sentinel read knote reports was acted on ahead of the unread Finished. That is on `main` too (the macOS entry for `node-tls-server.test.ts` in `test/flaky-tests.txt`: 7 of 48 recent builds of other branches), and this branch made it likelier (6 of 8 builds), since Finished now leaves in one segment with the close_notify. - **Error reporting, both engines**: #44422, #32929, #44516, #37094, #41272 + #42324 + #44223 as one change, #44021, #37472, #43946, #33630. One channel: a fatal error on an established session is reported, then **the engine closes the connection itself**, whatever the owner does with the report. `test/js/bun/net/tls-fatal-error-closes.test.ts` asserts closed-and-nothing-delivered for every owner (node:tls, `Bun.connect`, `Bun.listen`, `fetch` direct and through CONNECT, `Bun.serve`, `WebSocket` direct and through a proxy, Postgres, MySQL, Valkey, Duplex). - **Duplex engine** (`SSLWrapper`, `UpgradedDuplex`): #44462, #43529, #42332, #44464. #43877 + #44394 were in and are **out again**, see "Worth a look" 5. - **node:tls wrap lifecycle** (`net.ts`, `tls.ts`): #38007, #38058, #38028 + #38122 + #38076 as one change (six copies of the attach code become two helpers), #38311, #39008, #38154, #42340 + #42343 + #42339 + #42453 as one change, #43791, #42425, #44085, #42683, #39088, #39040, #40375, and what was still real of #36534. - **SNI, ALPN, server contexts**: #43080, #42050, #37195 + #43849 as one change (**one** SNI matcher for TCP and HTTP/3), #42355, #42285, #33253, part of #37896, part of #37013. A `tls.Server` has one `SSL_CTX`. - **Verification and options**: #44738, #41490, #37005 + the cwd pin of #40984, #31811, #43982, #33483 + #35245, #41810, #32235, #44441, #38092. - **node:tls API and CA store**: #41671, #38145, #32824, #43594, #39997, #41696, #33534, #34748, #42991, #42996, #42970. - **node:https, Agent, `ws`, node-fetch**: #41672 (https half), #41641, #38261, #42498, #44346, #35609, #31397, #42325. - **WebSocket client**: #41648, #37487 + #43048 as one change. - **SQL, Redis**: #33666, #41711, #44498, part of #42054. - **Tests only**: #41426, #40040, #44395, #44016, #37860, #40591, #44440, #41424. Found on the way and fixed here: an upload that a TLS 1.2 server interrupts with a renegotiation never completes on `main` (0 of 32 runs over `https.request`, `fetch`, `node:tls` and `Bun.connect`: the renegotiation ClientHello lands inside an application record that is still unsent, or the socket gets no `drain` again) and completes here, with two tests from robobun; the fix for #40653 (final flight and first write in one segment) stopped working whenever another TLS socket on the loop was stalled, on `main` too; the `tls.Server` prototype pinned the last server constructed and every `SSL_CTX` it owned; `Object.create(process.env).NODE_TLS_REJECT_UNAUTHORIZED = "0"` turned verification off process-wide once a `SHARE_ENV` worker existed; two debug panics when wrapping a shut-down or still-connecting socket; a `fetch` POST through a proxy sent its headers twice when the origin renegotiated; `BlockList` ignored IPv6 zone ids; a test now ties `root_certs.der` to `certdata.txt`. #### Behavior changes - **A server's `ca` without `requestCert` no longer asks for a client certificate** (`Bun.serve`, `Bun.listen`, HTTP/3, node:tls). It matches the docs and Node. On `main` such a server refused clients with no certificate but served any unrelated self-signed one, so it was never authentication. **Set `requestCert: true` to require a certificate.** A matrix test pins that `requestCert: true` still refuses no certificate and an untrusted one on 8 kinds of server, TLS 1.2 and 1.3, with `NODE_TLS_REJECT_UNAUTHORIZED` unset and `0`. - `NODE_TLS_REJECT_UNAUTHORIZED=0` no longer relaxes a server. - `Bun.connect` / `Bun.listen` hear of a fatal TLS error after the handshake through `error(socket, err)`. With no `error` handler the socket just closes. - HTTP/3 server names match like TCP: `*.` covers exactly one label, case is ignored, a trailing dot is ignored, the last registration of a name wins. - `requestCert` on node:https is `=== true`, as in Node. - An array where a generated options dictionary is expected throws (`tls: []`, `jest.useFakeTimers([])`). - `key` / `cert` arrays serve every identity. A client that can use both gets ECDSA, where `main` served whichever pair came last. - `ecdhCurve` is forwarded by node:https, `ws` and node-fetch now, so a group BoringSSL lacks (`X448`) throws there as it already does in `tls.createServer`. - A wrapped socket's error is re-emitted on the TLS socket as in Node, so `raw.destroy(err)` with a listener on `raw` only is uncaught, as in Node. - `sql.options.tls` is always an object, never `true`. `RedisClient` sends SNI. - `tls: { secureContext }` alone asks for TLS on `Bun.listen` / `Bun.connect` (it was plain TCP), and a value that is not a `SecureContext` throws. The context is served as it is: the `requestCert` / `rejectUnauthorized` it was created with hold whatever the options next to it say, and `requestCert` in the options over a context that does not ask throws at `listen()`. - `tls.DEFAULT_CIPHERS` reaches every client once assigned (`fetch`, `WebSocket`, `Bun.connect`, `RedisClient`, `Bun.SQL`, `S3Client`, proxy tunnels) and servers again. A list that selects no cipher throws `ERR_SSL_NO_CIPHER_MATCH` at the assignment. `fetch.preconnect()` dials nothing after an assignment. - The warning for an unreadable `NODE_EXTRA_CA_CERTS` is Node's one line, without the `warn:` prefix. - `BUN_CONFIG_WS_CLOSE_TIMEOUT` (default 30 s): how long a `WebSocket` client waits for the server to close the connection after the closing handshake. #### Worth a look in review 1. **#44529**: the kernel-refused remainder of a TLS write moves from the loop's one slot onto the connection (in the existing rare struct), so the write BIO never refuses a sealed record. Nothing is allocated on an unstalled path (200 writes: 0 appends, same `send()` count as `main`), memory with 16 stalled writers is lower than on `main` (276 KB vs 340 KB, which `main` holds inside BoringSSL's buffers), `us_socket_t` stays 80 bytes. It needs a bound on how long a deferred close waits, or a peer that stops reading pins the fd past `destroy()`: `US_SSL_CLOSE_AFTER_SPILL_TIMEOUT` is a fixed 10 s, not re-armed on progress. Separate commits, but the fix that keeps the client certificate off the wire beside a stalled socket builds on them. 2. **The default name check of node:tls also runs inside the handshake**, so a wrong-name server gets no client certificate on TLS 1.2 either. JS still runs it after every successful handshake, so a difference between the two matchers can only refuse. Error objects are byte-identical. 3. **#44441** widens trust by design: a self-issued leaf whose `keyUsage` lacks `keyCertSign` (`dotnet dev-certs`) is its own anchor when the store holds a byte-identical copy. No BoringSSL change. Expired pin, same subject with another key, wrong EKU and a pinned intermediate are tested to fail. 4. **#32235** only adds Ed25519 and ECDSA P-521 to the verify list. A captured ClientHello shows `main`'s list with the two inserted; `rsa_pkcs1_sha1` stays. 5. **A stream that a TLS socket wraps, when that TLS socket closes.** An earlier state of this branch lost data here while CI was green (found by #44709's report): with the peer closing first, 4 of 8 MiB arrived with TLS in TLS, 4 of 32 MiB on the http2 `emit("connection")` path, and a `write()` with no `'error'` listener ended the process. Three Node-parity changes only hold together: destroying the wrapped stream at the close (#38028 + #38122 + #38076, #38154) is safe only if every write has really completed (#43877), which in turn needs Node's handling of the peer's close_notify, which needs half-open sockets that the GC can collect. So: - #43877 + #44394 are reverted and reopened. A write over a stream completes once the stream has taken the ciphertext, as on `main`. - Until the verdict on the peer lets the session through, the application cannot have written over it. There the wrapped stream is destroyed as in Node, with the sessions below it. That keeps the release of the connection after a failed handshake, a rejected certificate and an early `destroy()`. The same for an http2 socket the application never got, and for `resetAndDestroy()`. - After that it is `main`'s teardown: a `net.Socket` only gets the engine's `end()`, closes at its peer's FIN, keeps its own timeout and reports its own errors. Any other stream is destroyed with the TLS socket. The regular suites cannot see any of this (999 files were green on every broken variant), so it was steered by eleven seeded differential fuzzers run on this build, `main`, Node v26.3.0 and the earlier state: close, `end()`, `destroy()`, `destroySoon()`, resets, hung and half-open peers, paused writers, timeouts, two and three sessions deep, over TCP and over Duplexes, before, at and after the handshake, and http2 requests. See "How did you verify". #### Known limits - `fetch` with a `checkServerIdentity` function still sends the client certificate (not the request) to a server the function refuses. On TLS 1.2 any verdict a JS callback gives is too late, as in Node. - `addContext()` / `SNICallback` still do not apply to a server-side socket on the stream engine (`emit("connection", duplex)`, TLS in TLS, unflushed writes, named pipes), as on `main`. - A CA bundled in a pfx extends an explicit `ca` only, for `ws` / node-fetch / `WebSocket`: the native `ca` can only replace the default store, and that store keeps `SSL_CERT_FILE` / `SSL_CERT_DIR`. - P-521 leaves work on TLS 1.3 only. TLS 1.2 needs secp521r1 in every ClientHello (`it.todo`). - Once `tls.DEFAULT_CIPHERS` is assigned, `fetch(url, { protocol: "http3" })` is `HTTP3Unsupported`, as with an explicit `ciphers`. - `addCACert()` by hand does not extend the chains of a context with several identities. - A throwing `ALPNCallback` sends `no_application_protocol` on both engines. Node sends nothing and its client sees `ECONNRESET`. - TLS in TLS, peer FIN while the outer handshake runs: the inner socket gets one `write EPIPE`, where Node gives `ECONNRESET` (`main` gives it no error at all). - `@SECLEVEL` in `ciphers` is dropped by the `ws` / node-fetch shims, which used to ignore `ciphers`. node:tls keeps throwing `ERR_SSL_INVALID_COMMAND`. - Beside a stalled TLS socket only the first record (16 KiB) of the first write leaves with the handshake flight. The rest goes record by record, which is what bounds the memory of stalled writers. - After a fatal error on an established session the socket emits `'error'` and then `'close'`. Node emits `'error'` and leaves the socket open. - A paused reader whose own write the kernel rejects loses what it had not read yet, with an `EPIPE`, as on Node. `main` reports no error there and delivers it. - On `main` too: a `Bun.listen` socket without `allowHalfOpen` that has unsent ciphertext when the client's `shutdown()` arrives loses that ciphertext (32 KiB), and over plain TCP `end()` with the peer still sending is a close over unread input, so a reset. - Differences from both `main` and Node that the differential runs below found and that stay, all with a peer that aborts: `ECONNRESET` instead of a clean `'end'` after the socket's own `'finish'` when the peer destroyed with unread data; under TLS 1.2, a zero-length `write()` followed by `destroy()` in `'secureConnection'` leaves the client without `'secureConnect'` (a plain `destroy()` there matches Node); a TLS 1.2 client that destroys in `'secureConnect'` gets no `'session'`; a `ClientRequest` whose handshake fails with an alert emits `'error'` and `'close'` but no `'finish'` (`writableFinished` is true). - Once `tls.DEFAULT_CIPHERS` is assigned, `fetch.preconnect()` opens nothing: `fetch()` then uses a context of its own, and a socket warmed under the default one would never be picked up. - A TLS `send()` that the kernel refuses outside a `write()` call (the drain of unsent ciphertext) is reported with the close, as `read EPIPE` / `read ECONNRESET`. Node says `write EPIPE`. `main` does not report it at all. - Once the application has a session over a `net.Socket` (TLS in TLS, http2 `emit("connection")`), a peer that never sends its FIN holds that socket after the TLS socket closed, as on `main`. Node destroys it. Two tests of #38154 are `todo` for this. Closing it any earlier (at its `'finish'`, say) makes the kernel drop what it has not sent yet as soon as the peer's close_notify arrives. - Plaintext that was queued on a socket before it was wrapped (STARTTLS with a backlog) is dropped when the TLS socket is destroyed, or its handshake fails, before the session is accepted. Node drops it too, except on `destroySoon()`. `main` sends it. - Over a stream that is no `net.Socket`, `end()` can still cut what that stream has buffered, and there is no backpressure, both as on `main` (#43877). - `tls.secureContext` (the undocumented door node:tls uses) is not read by a Windows named pipe listener, which builds its context from the options. On `upgradeTLS({ isServer: true })` the options next to it are the policy, as with Node's `SetVerifyMode`. - `selectServerName()` rebuilds the name tree per ClientHello for injected sockets of a server with `addContext()` entries: 0.4 µs for 1 entry, 3.7 µs for 10, 41 µs for 100, against 631–1111 µs for a handshake. #### Not included Left open, because they need a decision or are not TLS: #43877 + #44394 (see "Worth a look" 5; #43874 stays open with them), #38548, #38591 (both shrink who is trusted), #41589 (`verify-full` vs `NODE_TLS_REJECT_UNAUTHORIZED=0`), #37197, #41706, #43216, #33487, #33545, #36707, #32435, #37255, #28691, #40275, #30314 (features), #38120 (needs the BoringSSL fork, as did #33517, which the stale bot has closed since), #38529 (needs a Windows measurement), #34342, #38232, #43089, #44454, #40451, #42710, #44527, #38088, #38093, #41898. #37896, #42054 and #37013 stay open for the halves not taken. `http.createServer({ key, cert })` keeps serving TLS on purpose. One open question: `tls: {}` (an object that names no TLS option) is plain TCP on `Bun.listen` / `Bun.connect`, here and on `main`. It is the same trap as `tls: []`, but changing it changes a Bun default, so it is left alone. ### How did you verify your code works? - Every new test fails on `main` for the stated reason and passes here, except guards that pin existing behavior, each shown to fail when its clause is removed. `node:*` tests also pass on Node v26.3.0; the few that cannot say which Node version has the behavior. - 212 test files that touch TLS, sockets, http, http2, fetch, WebSocket, SQL, Valkey and workers: 6154 pass, 2 fail. Both are seen on `main` too: `serve.test.ts` "root range port" (the box runs as root), and `worker_threads.test.ts` "terminate(): nothing of the worker's runs after the request", which is flaky there and passed in the run below. - 58 of those files the way the ASAN lane runs them (LeakSanitizer + `BUN_JSC_validateExceptionChecks`): 58 files, 48 of them with leak checking, 4132 pass, 3 fail. All three also fail on `main`: `serve.test.ts` "root range port", `node-net.test.ts` "should not leak when connect({path}) fails synchronously on a reused handle" (times out under this environment), `worker_threads.test.ts` "process.exit() with a shell cp in flight" (a `ShellCpTask` leak). - 647 vendored `test-tls-*`, `test-https-*`, `test-net-*`, `test-http2-*`: the only two failures also fail on `main`. - The SNI matcher was diffed against both old matchers: 3 seeds × 1.23 M lookups × 3 registration flavours, every difference in one of the intended classes, TCP and HTTP/3 identical on every lookup. - The headline rows were also driven by hand with scripts against this build, `main` and Node v26.3.0: cleartext https, `crl`, `tls: []` / `{ secureContext }`, the `ca` / `requestCert` matrix, the client certificate on a wrong-name server, late `setSession()`, `destroy()` in `ALPNCallback`, `[rsa, ec]` identities with an intermediate from `ca`, `WebSocket` `checkServerIdentity`, a corrupted record, the Duplex read above, `tls.DEFAULT_CIPHERS`. - The `setSession()` guard was checked against the real `abort()` at 43 handshake states. - `bun run rust:check-all`: 12 of 12 targets. `tsc`, oxlint, source lints, prettier, rustfmt, mordant clean. - usockets' `_Nonnull` is compiled out of debug builds, so 105 of those files were also run on a local release ASAN build with the CI runner's environment (92 with leak checking): 4595 pass, 1 fail, `child_process.test.ts` "spawn reports EPERM after dropping privileges", which cannot pass as root and fails on `main` too. - The close of a TLS socket over another stream ("Worth a look" 5): eleven seeded differential fuzzers, 8,424 scenarios compared, each run on a release ASAN build of this branch, on `main`, on Node v26.3.0 and on the earlier state of the branch. Against `main`: - Data that `main` delivers in full is cut in 5 scenarios, and about 150 that `main` cuts arrive in full. Of the 5, in 2 `main` never notices the peer's close and keeps the socket for good, 2 call `end()` on the middle one of three sessions over an in-memory Duplex, and 1 does the same on Node. - No dead timeout, no silent reset and no uncaught error that `main` does not have (4 uncaught errors fewer). - A socket stays open where `main` closes it in 109, and closes where `main` keeps it in 295. 92 of the 109 do the same on Node or on the earlier state (a `destroy()` that an in-memory Duplex does not show its peer, half-open peers). 14 wait for a peer that paused reading and so does not read the FIN (#42332's backpressure, as in Node); the socket's own timeout fires there. 3 are left: one on a 5 ms timer, two with three sessions over an in-memory Duplex. - The earlier state of the branch cut data in 173 of the 400 scenarios of one of them, where `main` cuts none and this cuts none. - 23 new tests pin what they found. Each earlier attempt at this fix fails the ones that describe it, the earlier state of the branch fails 7, and all pass on Node. - After that change: 999 test files on the release ASAN build (20,246 pass; the 11 files that fail need a database, Docker, DNS or a non-root user, or share a temp directory with a parallel run and pass alone), 61 on the debug build. - TLS over a file descriptor (`openssl.c`, the path of `fetch`, `Bun.serve`, `tls.connect`, `Bun.connect`) got the same treatment after the rebase: seeded differential fuzzers on CI's release build of this branch, on `main` and, for `node:*`, on Node v26.3.0. Every runtime also against itself for the noise floor, injected faults and known bugs of `main` as positive controls, and a difference counts only if it shows in 5 of 5 fresh processes. - `node:tls` over TCP: 11,500 scenarios (one connection with Node as the oracle line by line; 2 to 60 connections beside stalled neighbours; raw peers that break the handshake). HTTPS: about 136,000 runs over `Bun.serve` + `fetch`, `node:https`, `node:http2` and `wss://`, also with the two ends in different runtimes. `Bun.connect` / `Bun.listen` / `upgradeTLS`: 11,500 scenarios and 720 slow connections, with writers driven by what `write()` returns, beside up to 6 stalled, dripping, closing or resetting neighbours, and plain TCP as a second oracle. No crash, hang, duplication, reordering or silent truncation, and no change in time or in connection reuse. - They found six things that `main` does better, none of which any test showed. All are fixed, each with a test that fails on the build before: what the peer sent lost behind a rejected `send()` (23 scenarios, and an early HTTPS response lost with only `EPIPE`), the same silently for a paused reader, `server.close()` never calling back on a half-open server after a ClientHello and a reset (17), `closeAllConnections()` taking 12 s with a stalled client, `end()` losing up to 1.3 of 4 MiB that `write()` had reported while the peer still uploads, and `end()` a little after a stall never closing beside other stalled TLS sockets. The last two fixes also deliver the 1 to 2 MiB that `main` loses there, and close the socket that `main` keeps for good without such neighbours. - All of them again after every fix, on CI's release build of it. That caught one regression of a fix itself (a reader stopped for backpressure lost 86,385 bytes, 1 of 6,000 scenarios), fixed too. On the last build: scenarios that lose data where `main` does not 23 → 2, and Node loses it in both, with the same `EPIPE`; `server.close()` that never calls back 17 → 0; connections held 4 → 0; requests that end in an error only where `main` has a response 6 → 0. With a Node server in another process, a request ends in an error only in 8 and 10 of 1,500 scenarios here, 5 and 3 on `main`, 10 with Node as the client. - `Bun.connect` / `Bun.listen` on the last build against `main`, in scenarios: hangs 0 against 1,031, sockets and fds never released 0 against 965, corrupted data 0 against 345, `abort()` 0 against 26 (`setSession()` after the handshake), writers that never close 0 against 101 of 720 connections. No kind of failure shows here and not on `main`. About a third of the slow connections close later than on `main`, in 1 to 16 s instead of at once, waiting for unsent ciphertext or for the peer's close_notify, and 79 more of them deliver all that `write()` reported. RSS and time with 16 to 256 stalled writers are the same. - What they found that `main` does worse: a `WebSocket` that calls `close()` with sends pending loses messages in 81 of 999 scenarios (0 here), 37 server sockets left open, 10 `server.close()` that never call back, 20 write callbacks that never run. - The kqueue fix cannot be run on Linux. The `connectionListener` count test now says what became of a missing connection, which is how the cause was found (`'tlsClientError'` "socket hang up", then `read ECONNRESET` at the client of the same port, after its `'secureConnect'`). On macOS x64 it failed every attempt of the three builds before the fix and passed at the first attempt of the build with it. - Windows and macOS were only run by CI. Four new tests asserted what only the Linux kernel does (a FIN read ahead of a reset, unread bytes surviving a reset, loopback buffer sizes, `fstat()` on a socket) and now say so per platform. --------- Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com> Co-authored-by: robobun <117481402+robobun@users.noreply.github.com>

github-actions Bot added the claude label Aug 13, 2026

test: wait for the client close without turning a client error into a…

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github-actions Bot reviewed Aug 13, 2026

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Comment thread src/js/internal-for-testing.ts

github-actions Bot reviewed Aug 13, 2026

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Comment thread src/uws_sys/lib.rs

test: account for the ECONNRESET shaping fatal write errnos get on Wi…

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…ndows

claude Bot reviewed Aug 13, 2026

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Comment thread packages/bun-usockets/src/socket.c

Comment thread packages/bun-usockets/src/socket.c

usockets(tls): report the fatal write as UV_EPROTO on Windows so it n…

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…ames as EPROTO

github-actions Bot reviewed Aug 13, 2026

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Comment thread src/uws_sys/socket.rs

claude Bot reviewed Aug 13, 2026

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This was referenced Sep 6, 2026

tls: report a fatal post-handshake SSL error instead of a clean close #41463

Closed

node:http2: report a peer reset that a client write sees first #42182

Open

Merge branch 'main' into farm/a2387786/tls-fatal-write-close

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coderabbitai Bot reviewed Sep 11, 2026

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Comment thread packages/bun-usockets/src/crypto/openssl.c Outdated

robobun added 2 commits September 11, 2026 06:26

socket: use eq_ascii for the ssl_write fault name after the merge fro…

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…m main

claude Bot reviewed Sep 11, 2026

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Comment thread src/runtime/socket/socket_body.rs Outdated

ci: retrigger

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claude Bot reviewed Sep 11, 2026

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This was referenced Sep 11, 2026

tls: report a fatal post-handshake SSL error over a Duplex or a named pipe #42324

Closed

tls: report a rejected send() as a write error instead of a clean close #42336

Closed

robobun mentioned this pull request Sep 21, 2026

node:net: finish an accepted socket whose native close leaves a write parked #43698

Merged

robobun mentioned this pull request Oct 3, 2026

tls: queue unsent ciphertext per connection so write() counts every sealed record #44529

Closed

Jarred-Sumner mentioned this pull request Oct 6, 2026

tls: consolidate the open TLS fixes (both engines, node:tls, node:https, WebSocket, SQL) #44618

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Jarred-Sumner closed this Oct 6, 2026

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