node:net: cancel the in-flight write when the socket is destroyed

[robobun]

Land before or together with #43877 (Notes).

Problem

• socket.write(chunk, cb) never calls cb when the peer resets while the write waits for the native drain. Bun: ["error ECONNRESET read","close"]. Node v26.3.0: ["error ECONNRESET read","write cb ECANCELED write","close"].
• Cause: SocketHandlers2.close (src/js/node/net.ts:1572) and SocketEmitEndNT (net.ts:878) call self.destroy(er) on a read error. They return before the block that fails the parked write.
• destroy() fails such a cb with ERR_SOCKET_CLOSED, synchronously.

Fix

• _destroy takes the parked callback before the handle closes. It fails it on the next tick with write ECANCELED, after 'error', before 'close'.
• With no error, the cancel tick goes first, ahead of the 'end' from the native close handler's EOF.
• A write that waits for 'connect' or the TLS handle keeps its own 'close' path.
• Verified: node-net.test.ts, node-tls-connect.test.ts, under bun and (on POSIX) Node 24+. The 12 bun cases fail on main. Self-reviewed: 14 concerns, 13 addressed (Notes).

Background

• The native socket buffers what the kernel does not take. _write parks the stream callback in kwriteCallback until the native drain.
• In Node, libuv owns the queued write. uv_close fails it with UV_ECANCELED (uv__stream_destroy).
• Considered a fix in each close handler (net: invoke the pending write callback when a read error destroys the socket #33401). One hook in _destroy also covers destroy() and TLS.

Downsides

• A write callback that destroy() cancels now runs one tick later, with ECANCELED.
• A same-tick destroy() then connect() with a write in flight fails the new connection, as in Node.
• A _destroy with no write in flight pays 2 calls, 3 branches, 1 property read. No allocation or queue entry.

Notes

Test fixture (3dacc58195, 2026-09-25). This commit changes only the fixture in node-net.test.ts. The fixture wrote 1 MB chunks until one write did not complete inside write(), and ran the teardown in the same tick. Under Node on macOS that write sometimes reported write ok in place of write ECANCELED write:

darwin lanes, node-net.test.ts	attempts that passed
builds 118029, 118057, 118090 (before the rebase)	6 of 6
build 120615 (after the rebase: the same fixture bytes, 4 more tests in the file)	2 of 5
build 120621 (3dacc58195, 64 MB chunks)	2 of 2

• Cause: for Node, a write is in flight when the first send is partial. libuv then sends a second time inside the same write(): uv_try_write, then uv__write from uv_write2. If the second send takes the rest, the request is complete with status 0 before destroy() runs, and uv_close finds nothing to cancel. After a teardown in the same tick, write ok has no other source.
• On Linux the kernel takes 2.5 MB (2,633,835 bytes, 3 of 3 runs under Node) for a peer that never reads. The old fixture left 0.5 MB of the last chunk in the queue of libuv. I have no macOS machine, so I did not measure the numbers there.
• Fix: the chunk is 64 MB (a corked batch is two chunks of 32 MB). On Linux 61.5 MB now stay in the queue. The TLS fixture already used one 64 MB write, and it passed on the darwin lanes in 8 of 8 runs.
• On Windows the kernel takes the first two 64 MB writes whole (the first three with 1 MB chunks), so a later write is the one in flight there. The loop stays for that reason.
• Cost: peak RSS of one fixture process under a release build of bun. Linux x64: 99 MB, was 39 MB (corked batch: 163 MB, was 42 MB). Windows x64: 151 MB, was 25 MB (corked batch: 245 MB, was 28 MB). Under Node on Linux it stays at 45 MB.
• Checked with the new fixture. Linux x64 debug build: 10 bun cases and 10 Node cases pass, and the 10 bun cases fail with main's net.ts. Node alone: 10 of 10 runs for each case. Windows x64 debug build: the two test files pass in 3 of 3 runs (211 pass, 14 skip, 0 fail). macOS: not run locally. In CI build 120621 the two test files passed on the first attempt on every lane, darwin x64 and aarch64 included.

Found outside this PR: the two darwin x64 test jobs of build 120615 ended at 13:27 UTC when the nightly cleanup of the macOS hosts removed the checkout under them (uv_os_get_passwd returned ENOENT). #43629 and #43611 are open for that.

Rebase onto main (29d9638da3, 2026-09-25). The branch was 101 commits behind and did not merge. The rebase left one commit, eb3904deb9, and squashed the earlier commits, so the commit ids in the notes below (46a274f610, dae326ee31, 7aa6ccca4d, cf967167f6) refer to that history. Five PRs changed src/js/node/net.ts on main in between:

• Typecheck the built-in modules (src/js) in CI #43649 typechecks src/js in CI. bun run build:types && bun x tsc --noEmit -p src/js/tsconfig.json gives 0 errors on this head.
• node:net: finish an accepted socket whose native close leaves a write parked #43698 changed the last block of SocketEmitEndNT: it fails a parked write when kclosed is set, for a native close that carries no error. This PR covers the read-error branch, which returns before that block. With this PR _destroy has taken the write before the close handler looks for it.
• node:net: return false from write() when the send fails at once #43755 makes _write fail at once when the send fails at once. Such a write is never parked, so there is no overlap.
• node:tls: keep unread data and still emit 'close' when a wrapped transport closes #42176 and node:tls: report a closed connection on the TLS socket, not on the socket it wraps #42487 added closeWithTLSSocket and closeOwedRaw. _destroy held the one conflict in net.ts: closeOwedRaw(this, upgraded) now follows finishDestroy(callback, err, canceledWrite) in both branches, so main's order (queue 'error', then close the wrapped socket) is kept.
• The other conflict was one import line in node-tls-connect.test.ts. Both sides are kept.

Event order for a TLS client over a net.Socket (tls.connect({ socket })) with a 64 MB write in flight, after the rebase. It records the TLS socket and the socket it wraps. Each row is 10 of 10 runs:

teardown	Node v26.3.0 and this branch	main (29d9638da3)
destroy()	write ECANCELED write, raw close, tls close false	write ERR_SOCKET_CLOSED, raw close, tls close false
destroy(err)	tls error EBOOM, write ECANCELED write, raw close, tls close true	write ERR_SOCKET_CLOSED, tls error EBOOM, raw close, tls close true
peer reset	tls error ECONNRESET read, write ECANCELED write, raw close, tls close true	tls error ECONNRESET read, raw close, tls close true. No write callback.

Tests after the rebase, debug builds:

build	net, bun cases	net, Node cases	TLS, bun cases	TLS, Node cases
Linux x64, src/ at main	10 fail	10 pass	2 fail	2 pass
Linux x64, this branch	10 pass	10 pass	2 pass	2 pass
Windows x64, this branch (3 runs)	8 pass, 2 skip	not run	1 pass, 1 skip	not run

On Windows the two test files pass as a whole: 211 pass, 14 skip, 0 fail. On Linux, every test that fails on this branch in test/js/node/tls (2 of 406) and test/js/node/net (12 of 317) also fails with main's net.ts.

net.Socket write > should allow reconnecting after end() in node-net.test.ts is flaky on a loaded machine, with main's net.ts too: 5 of 20 runs fail on main and 6 of 20 on this branch. It reconnects 3 ms after end() and does not wait for 'close'. A trace of the same steps shows that _destroy finds no parked write there, so the new code does not run in it.

With #43877. #43877 makes a TLS write park its callback until the transport has taken the ciphertext. It uses the same kwriteCallback slot, so more writes are in flight at teardown, and it does not settle them on a read error. The two branches merge cleanly except for one import line in node-tls-connect.test.ts (keep both sides).

I built that merge (eb3904deb9 + 9ee76d60e0) and swapped only net.js between the rows, so the native code is the same in all Bun rows. The client has a 64 MB write in flight and idle (the server never reads), then the server resets the connection. The server always runs under Node.

TLS client	Node v26.3.0 (20 runs)	main + #43877 (50 runs)	main + #43877 + this PR (50 runs)
over a net.Socket	error ECONNRESET read, write ECANCELED write, close true	error ECONNRESET read, close true. The write callback is never called, 50 of 50.	same as Node, 50 of 50
over a generic Duplex	error ECONNRESET read, write ECANCELED write, close true, error ECANCELED write	write ERR_SOCKET_CLOSED, close false	write ECANCELED write, close false

Over a Duplex the write callback runs in both Bun rows, and this PR gives it Node's error. The TLS socket still gets no 'error' and closes with hadError false there. That is the transport's error not reaching the TLS socket, which is the subject of #42235, not of this PR.

Repro (plain bun file.js and node file.js, no fault injection):

const net = require("node:net");
const events = [];
const server = net.createServer(sock => {
  sock.on("error", () => {});
  sock.pause();
  setTimeout(() => sock.resetAndDestroy(), 300);
});
server.listen(0, "127.0.0.1", () => {
  const c = net.connect(server.address().port, "127.0.0.1", () => {
    const ok = c.write(Buffer.alloc(64 * 1024 * 1024, 0x41), err =>
      events.push(`write cb ${err ? err.code + " " + err.syscall : "ok"}`));
    events.push(`write returned ${ok}`);
  });
  c.on("error", e => events.push(`error ${e.code} ${e.syscall}`));
  c.on("close", () => {
    events.push("close");
    setTimeout(() => { console.log(JSON.stringify(events)); server.close(); }, 200);
  });
});

Event order, one write in flight and three queued behind it (Linux, same script under each runtime):

teardown	Bun 1.4.3 and main	Node v26.3.0 and this branch
peer reset (client or accepted socket)	error ECONNRESET read, close. No write callback runs.	error ECONNRESET read, write ECANCELED write, queued ECONNRESET read, close
destroy()	write ERR_SOCKET_CLOSED (inside destroy()), queued ERR_SOCKET_CLOSED, close	write ECANCELED write, queued ECANCELED write, close
destroy(err)	write ERR_SOCKET_CLOSED, queued err, error, close	error, write ECANCELED write, queued err, close
TLS destroy()	callback after close, or never	write ECANCELED write, close

I ran 14 plain TCP scenarios and 5 TLS scenarios (client and accepted socket, peer reset, peer destroy(), destroy(), destroy(err), resetAndDestroy(), end() then reset, with and without queued writes). Each one records error, end, finish, close and every write callback. This branch gives the same sequence as Node v26.3.0 in all 19. In each of them the socket that holds the write still reads. A socket that does not read gets different errors than in Node (#43381, item 3). The error also has the same shape as in Node: message: "write ECANCELED", code, errno: -125, syscall: "write".

Self-review. Concerns raised and what happened to each:

• The position of the cancel tick matters when there is no error. If it is queued after callback(err), the 'end' that follows the EOF from the native close handler runs before the write callback. The node:http client then reports socket hang up first and drops the request's 'finish'. For req.destroy() during an upload, Node and main give finish, error ECONNRESET, and that order gave error ECONNRESET. Addressed: with no error the cancel tick goes first. The new tests record 'end', so they fail if the tick moves.
• A wrapped Duplex that emits 'close' synchronously from upgraded.destroy() can reach the native close handler. Addressed: _destroy takes the callback before that call.
• The peer-reset test needs the read error to reach the socket before a writable event. Linux delivers a loopback RST before the close() that sends it returns. I could not check macOS. Addressed: that case runs on Linux only. The destroy() cases and the TLS case run on every platform.
• The comment on takeInFlightWrite said that a 'close' listener always fails a write that waits for 'connect'. Addressed: the comment now states only what the check relies on.
• Not changed: destroy() then connect() in the same tick, with a write in flight, now fails the new connection with write ECANCELED. Node v26.3.0 does the same: the same script prints ["error ECANCELED write","close false","close true"] under Node and under this branch, and ["reconnected","close false"] under 1.4.3. undestroy does not reset the write that is in flight. A reconnect from 'close' is not affected, because the cancel runs before 'close'.
• A throw from the callback passed to destroy(err, cb) left _destroy before the error-path cancel tick was queued, so the write and the writes behind it never settled. Addressed: finishDestroy queues the tick from a finally block. Node, and this branch, give write ECANCELED write, queued EBOOM, close true and no 'error' (the stream swallows the throw before it queues 'error'). A new test case pins this. The same gap remains for a throw from upgraded.destroy() or terminate() when there is an error. Such a throw leaves _destroy before it closes the handle, on main too.

Second review round. Addressed in dae326ee31:

• The tests did not run under Node. Addressed: each file now has one CommonJS fixture that runs under bunExe() and under nodeExe() (Node 24 or later, because v22.0.0 still passed no error to a canceled write). The expected output is the same for both.
• A TLS socket over a socket that is still connecting opens without 'connect'. The 'close' listener that _write adds for a write made while connecting then outlived the wait, and after the cancel it called the same _write callback a second time (ECANCELED, then ERR_SOCKET_CLOSED_BEFORE_CONNECTION). Writable ignores the second call, so the public events were right, but Node and 1.4.3 call it one time. Addressed: the listener checks that the write is still the parked one, as onUpgradeWriteClose does. The new TLS case fails without the check.
• On Windows the Node cases failed in CI (build 118029): the TLS case threw from its precondition check (the write did not stay in flight: write ok) and one net case was flaky. I measured the reason on Windows x64: a 64 MB write to a peer that never reads completes after one loop turn, under Node 26.3.0 and under Bun, and it never completes on Linux. So Node cannot pin a write in flight there. Addressed in cf967167f6: the Node cases run on POSIX only (runtimesWithNode(24, { nodeOnWindows: false })). The bun cases run on Windows and pass there (8 net and 1 TLS, 3 runs, debug build).
• The Node version probe of the two test files was the same six lines (a review nit). Addressed in 7aa6ccca4d: runtimesWithNode(minNodeMajor) in test/harness.ts.
• A corked batch in flight had no test. Addressed: destroy() with a corked batch in flight. Node and this branch give the same sequence for destroy(), destroy(err) and a peer reset with a batch.
• Differences from Node that this PR does not change now have a tracker: node:net, node:tls: socket teardown events that still differ from Node (spurious 'end', ERR_SOCKET_CLOSED in place of the real error) #43381 ('end' on a plain destroy(), ERR_SOCKET_CLOSED in place of the real error with no 'error' listener and on a peer close during the TLS handshake, a socket that does not read, the Windows drain contract). Upstream test-tls-writewrap-leak.js still times out, with net.ts from main and from this branch.

Order with open PRs.

• node:tls: complete write(cb) and end(cb) over a Duplex when the stream completes the ciphertext #43877: land this PR before it or together with it. See "With node:tls: complete write(cb) and end(cb) over a Duplex when the stream completes the ciphertext #43877" above.
• node:net: queue what EAGAIN leaves of a write to an adopted fd, cancel it on destroy() #41835 adds a byte-identical cancelWriteNT and its own canceledWrite in _destroy for the adopted-fd sink. The PR that lands second must keep one helper and one local, for example canceledWrite ??= takeInFlightWrite(this).
• node:net: hold queued _writev chunks by reference instead of concat + native copy #35940 keeps the chunks of an in-flight _writev batch in _pendingData. takeInFlightWrite reads a non-null _pendingData as "not handed to the native handle", so that batch would not be canceled. The corked-batch test fails in that case. node:net: hold queued _writev chunks by reference instead of concat + native copy #35940 must then give takeInFlightWrite another way to tell the two states apart.

Not reached by this PR. child.stdin is a Writable over a FileSink (src/js/node/child_process.ts:1261), not a net.Socket. Extra "pipe" stdio slots are net.Sockets and get the new behavior.

Windows. A peer reset reaches a socket with a write in flight as a writable event first. on_writable keeps its legacy drain contract there (see the comment in src/runtime/socket/socket_body.rs), so the close path never sees a parked write, and this change does not alter that flow. I checked the destroy() cases and the TLS case on a Windows debug build: they pass.

Older difference that this PR does not touch. The native close handler pushes EOF into a stream that is already destroyed, so Bun emits 'end' before 'close' on a plain destroy() with no write in flight. Node emits only 'close'. #43381 tracks it (item 1).

Paths that still use ERR_SOCKET_CLOSED. A native close that arrives while the socket is not destroyed (no error, or an error with no 'error' listener) still fails the parked write from the close handler. A write that waits for the TLS handle still fails from its 'close' listener. #43381 tracks them (items 2 and 4).

Related PRs.

• net: invoke the pending write callback when a read error destroys the socket #33401 had the same goal on an older net.ts. The stale-PR cleanup closed it unmerged.
• tls: minDHSize validation, replaceable createSecureContext, ECANCELED on cancelled TLS writes (+5 tests) #35386 (draft) removes the same early return in SocketHandlers2.close. It gives ECANCELED to TLS sockets only and keeps ERR_SOCKET_CLOSED for plain TCP. The two changes compose: _destroy takes the callback first, so the close handler finds none.
• node:net: fail the write when the flush at the end of the open dispatch gets a fatal send error #43026 covers the fatal send errno at the end of the open dispatch. The new tests write outside that dispatch, so they do not depend on it.

Suites. test/js/node/net, tls, http, http2 with bun bd test. The Node suite's test-net-*, test-tls-*, test-http2-*, test-http-*, test-https-*, test-cluster-*, test-child-process-*, test-pipe-*. I compared every failure with a build of main. The failures are the same on main, or they are timeouts that pass when the test runs alone. After dae326ee31 I ran test/js/node/net, test/js/node/tls and the Node suite's test-net-* and test-tls-* again, with the same result.

---

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-connect.test.ts, test/js/node/net/node-net.test.ts

[robobun]

Status: rebased onto main (29d9638da3) on 2026-09-25. The branch has two commits: eb3904deb9 is the change, and 3dacc58195 changes only the net test fixture. CI is green on 3dacc58195: build 120621 passed 181 of 181 jobs, and the two new test files passed on the first attempt on every lane. The PR waits for a maintainer review. Land it before or together with #43877. #43381 tracks the teardown differences from Node that this PR does not change.

How I reproduced it

1. Real kernel, no fault injection. The script is in the Notes of the PR body. A client writes 64 MB to a server that never reads, then the server calls resetAndDestroy().

   bun repro.js    # 1.4.3 canary (367d939d9), and a debug build of main (29d9638da3)
   ["write returned false","error ECONNRESET read","close"]
   
   node repro.js   # v26.3.0
   ["write returned false","error ECONNRESET read","write cb ECANCELED write","close"]
   

2. The new tests. Each file has one CommonJS fixture that runs under bun and, on POSIX, under the system Node (24 or later), with one expected output for both. The net fixture writes 64 MB chunks until one write stays in flight (the first one on Linux and macOS), queues one more write, then tears the socket down: peer reset, destroy(), destroy(err), destroy(err, cb) with a cb that throws, and destroy() with a corked batch in flight, each for a client socket and for an accepted socket. The TLS fixture covers destroy() on an established connection, and a peer reset during the handshake with a write made while the wrapped socket was still connecting.

   The net chunk was 1 MB until 3dacc58195. Under Node on macOS, the second send that libuv makes inside write() could take the rest of that chunk. The write was then complete before the teardown and reported write ok (3 of 5 attempts on the darwin lanes of build 120615). The kernel cannot take 64 MB for a peer that never reads. The Notes of the PR body have the numbers.

   bun bd test test/js/node/net/node-net.test.ts -t "socket torn down with a write still in flight"
   bun bd test test/js/node/tls/node-tls-connect.test.ts -t "TLS socket torn down with a write still in flight"
   

   build	net, bun cases	net, Node cases	TLS, bun cases	TLS, Node cases
   debug build, src/ at origin/main (29d9638da3)	10 fail	10 pass	2 fail	2 pass
   debug build, src/ at this branch	10 pass	10 pass	2 pass	2 pass
   1.4.3 canary 367d939d9 (USE_SYSTEM_BUN=1)	10 fail	10 pass	2 fail	2 pass

   The table is from Linux x64 with Node v26.3.0, measured with the fixture of 3dacc58195. The peer-reset cases run on Linux only. The reason is in the test comments and in node:net, node:tls: socket teardown events that still differ from Node (spurious 'end', ERR_SOCKET_CLOSED in place of the real error) #43381, item 5.

   On Windows only the bun cases run. A 64 MB write to a peer that never reads completes there after one loop turn, under Node 26.3.0 and under Bun (on Linux it never completes), so Node cannot pin a write in flight. With that leg still on, the TLS Node case failed in CI build 118029 and one net Node case was flaky. On a Windows x64 debug build of this head the bun cases pass: 8 net and 1 TLS, in each of 3 runs. The two test files pass there as a whole: 211 pass, 14 skip, 0 fail.

3. With node:tls: complete write(cb) and end(cb) over a Duplex when the stream completes the ciphertext #43877 merged in (a local merge of eb3904deb9 and 9ee76d60e0). A TLS client has a 64 MB write in flight and idle, then the peer resets. The server runs under Node. Only net.js differs between the Bun rows.

   TLS client	Node v26.3.0 (20 runs)	main + node:tls: complete write(cb) and end(cb) over a Duplex when the stream completes the ciphertext #43877 (50 runs)	main + node:tls: complete write(cb) and end(cb) over a Duplex when the stream completes the ciphertext #43877 + this PR (50 runs)
   over a net.Socket	error ECONNRESET read, write ECANCELED write, close true	the write callback is never called	same as Node
   over a generic Duplex	error ECONNRESET read, write ECANCELED write, close true, error ECANCELED write	write ERR_SOCKET_CLOSED, close false	write ECANCELED write, close false

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Walkthrough

Socket destruction now cancels eligible in-flight writes. Socket and TLS tests verify cancellation errors, callback behavior, and event ordering during clean destruction, errored destruction, and peer resets.

Changes

Socket write cancellation

Layer / File(s)	Summary
Cancellation lifecycle src/js/node/net.ts	Eligible in-flight writes are detached before handle teardown and completed with UV_ECANCELED. Clean and errored destruction use different callback ordering. Connecting writes avoid duplicate callback completion.
Socket teardown validation test/js/node/net/node-net.test.ts	Tests cover peer resets, clean destruction, errored destruction, throwing destroy callbacks, corked writes, and client and server sockets.
TLS teardown validation test/harness.ts, test/js/node/tls/node-tls-connect.test.ts	The harness selects compatible Node runtimes. TLS tests verify canceled writes and close-event ordering for established and connecting sockets.

Suggested reviewers: cirospaciari

Priority: ➖ Normal

Merge Risk: ⚪ Minimal · up to 3dacc

The change cancels parked writes during socket teardown, and the supplied summaries describe net and TLS coverage for callback and event ordering. The prior callback-dispatch concern is not an established guideline violation, so no merge-blocking risk is identified.

🚥 Pre-merge checks | ✅ 4

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Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
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 describes the main change: canceling an in-flight write when a socket is destroyed.
Description check	✅ Passed	The description thoroughly explains the problem, implementation, verification steps, expected behavior, platform coverage, and known limitations. It does not use the template headings exactly, but it …

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[claude]

Nothing blocking. The comments below are optional suggestions. There is no need to push a fix for them before merging.

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Inline comments:
In `@src/js/node/net.ts`:
- Line 272: Update cancelWriteNT to invoke the user-supplied callback through
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[claude]

I re-reviewed after the follow-up commit and found no bugs; the taken write is now settled from a finally, so a throwing destroy(err, cb) callback no longer loses it. Because this changes nextTick ordering inside Socket.prototype._destroy for every node:net/node:tls teardown, a human look is still worthwhile.

What was reviewed:

• takeInFlightWrite vs the three _write parking paths: connecting and pending-upgrade writes keep _pendingData set and are left to their 'close' listeners; only a write parked after $write returned 0 is taken.
• Cancel placement: 'close' is always emitted from setImmediate (closeSocketHandle, closeAdoptedTLSRawNowNT, terminate path), so the nextTick cancel lands before it in every branch; with err it follows the emitErrorCloseNT tick that onDestroy queues.
• Test matrix: the recorded-callback trick in the write loop relies on Writable deferring sync callbacks to nextTick, so only the in-flight write reports; base emits ERR_SOCKET_CLOSED/no callback, so each case fails without the fix.

Extended reasoning...

Overview

The PR changes Socket.prototype._destroy in /home/claude/bun/src/js/node/net.ts to take the write callback parked in kwriteCallback before the native handle closes and fail it on the next tick with ErrnoException(UV_ECANCELED, "write"), matching libuv's uv__stream_destroy. Three small named helpers are added (takeInFlightWrite, cancelWriteNT, finishDestroy). Tests are added alongside existing coverage in test/js/node/net/node-net.test.ts (client/server x reset/destroy()/destroy(err)/destroy(err, throwing cb)) and test/js/node/tls/node-tls-connect.test.ts (TLS destroy()).

Security risks

None identified. The change only affects the timing and error code of a write callback during teardown; no new parsing, no new network surface, and errors are routed through the existing ErrnoException machinery rather than hand-assigned .code.

Level of scrutiny

Moderate-to-high. _destroy is on every socket teardown path (plain TCP, TLS, wrapped duplex, resetAndDestroy, _closeAfterHandlingError), and the correctness argument rests on nextTick-vs-setImmediate ordering: the cancel must land after the 'error' tick that onDestroy queues and before the 'close' that closeSocketHandle/closeAdoptedTLSRawNowNT/the terminate branch emit from setImmediate. I traced each branch and the ordering holds, and the no-error case deliberately queues the cancel before the native close so state.errored is set before endReadableNT can emit 'end'. The remaining gap I noted in the prior run (a throw from a user Duplex's destroy() at the kupgraded teardown when err is set) is unchanged, but the base behaved the same or worse there, and it is already recorded inline.

Other factors

The second commit directly addressed the one inline finding from the earlier review by wrapping callback(err) in try/finally. I could not build a debug binary in this environment, so I did not execute the new tests; my confidence comes from reading _write, closeSocketHandle, and src/js/internal/streams/destroy.ts and confirming the asserted sequences follow from that code. The tests await 'close' rather than sleeping, reuse a single 1 MiB chunk, and gate the platform-dependent peer-reset case on Linux with a stated reason. Because this is a behavioral compat change on a hot path with several sibling teardown routes, a maintainer familiar with the net/TLS close ordering should still sign off.

[claude]

Nothing blocking. The comments below are optional suggestions. There is no need to push a fix for them before merging.

Beyond the inline nit, I re-checked the destroy(err, cb)-throws path raised on the previous push: finishDestroy now queues the cancel tick from a finally, and the new "cb that throws" case in node-net.test.ts pins the settled order. I also checked the _pendingData != null gate in takeInFlightWrite: the post-connect branch of _write nulls _pendingData before $write (net.ts:2847), so only writes that actually reached the handle are taken, and pre-connect / pre-upgrade writes stay with their existing 'close' listeners.

Extended reasoning...

This push addresses the only substantive finding from the prior review (a user destroy(err, cb) callback that throws previously exited _destroy before the error-path ECANCELED tick was queued). The fix routes callback(err) through finishDestroy, whose finally schedules cancelWriteNT, and a new test case asserts ["write ECANCELED write", "queued EBOOM", "close true"] for that scenario. The takeInFlightWrite gate relies on _pendingData being undefined/null only once a write has been handed to the native handle; _write sets it to null immediately before socket.$write and the pre-connect / pre-upgrade branches set it to the chunk, so the gate distinguishes the two states correctly. The remaining inline finding is a duplicated Node-version probe across two test files, which is a style nit. The change still alters event ordering during socket teardown for both node:net and node:tls, so a human maintainer's look at the ordering contract is worthwhile rather than an automated approve.

[robobun]

^{Updated 7:46 AM PT - Sep 25th, 2026}

✅ @robobun, your commit 3dacc58195a00ff1e121a55fc2737eab787b4b2c passed in Build #120621! 🎉

---

🧪   To try this PR locally:

bunx bun-pr 43250

That installs a local version of the PR into your bun-43250 executable, so you can run:

bun-43250 --bun

[claude]

I re-reviewed the latest push and found no bugs; the two points from earlier rounds (settling the taken write when a destroy(err, cb) callback throws, and sharing the Node-version probe) are addressed in the code by finishDestroy and runtimesWithNode. Because this changes the teardown ordering of every node:net/node:tls socket with a write in flight, a human look at the event-order contract is still worthwhile.

What was reviewed:

• takeInFlightWrite only takes a callback whose chunk already reached the native handle (_pendingData == null); writes parked on 'connect' or the TLS attach still settle through their own 'close' listener, and the new kwriteCallback !== callback guard in _write's connecting path prevents a double callback on wrapped sockets that never emit 'connect'.
• Tick ordering against internal/streams/destroy: with no error the cancel tick is queued before callback(err); with an error it is queued after the 'error' tick, and net's 'close' is emitted via setImmediate on every handle branch (plain, _closeAfterHandlingError, resetAndClosing, adopted TLS raw), so 'error' -> write cb -> 'close' holds.
• Native drain/error/close handlers that run after _destroy see a null kwriteCallback and become no-ops, so no path invokes the taken callback twice.
• Fixture correctness: the nth === writes check works because Writable defers user callbacks of synchronous writes to the next tick, so only the last (in-flight) write reports; a corked batch shares one callback and reports twice as expected.

Extended reasoning...

Overview

The PR changes Socket.prototype._destroy in src/js/node/net.ts to take the in-flight write callback (kwriteCallback) before any handle close, and to fail it on the next tick with ErrnoException(UV_ECANCELED, "write"), positioned before 'close' and after 'error' to match Node/libuv. A finishDestroy wrapper guarantees the error-path cancel tick is queued even when the user's destroy(err, cb) callback throws. The connecting-path onClose listener in _write gains an identity guard so a wrapped socket (which never emits 'connect' and so never removes that listener) does not fire the callback a second time. test/harness.ts gains nodeMajorVersion()/runtimesWithNode(), and the two test files add describe.each matrices run under Bun and Node >= 24.

Security risks

None identified. The change does not touch TLS verification, credentials, or parsing of untrusted input; it only alters when and with which error object an already-registered JS callback is invoked during socket teardown.

Level of scrutiny

High. Socket teardown ordering in node:net is contract that node:http, node:http2, node:tls, and userland pools depend on. I traced the two callback-invocation orders against src/js/internal/streams/destroy.ts (emitErrorCloseNT emits 'error' on a nextTick; the stream-level emitCloseNT is a no-op because Socket sets emitClose: false, and net's own 'close' is emitted via setImmediate in closeSocketHandle, closeAdoptedTLSRawNowNT, and the resetAndClosing branch, or via nextTick after finishDestroy in the no-handle branch). In all branches the cancel tick lands after 'error' and before 'close'. I also checked every other reader/writer of kwriteCallback (SocketHandlers.drain/error, SocketHandlers2.close/error, SocketEmitEndNT, finishSocketEnd, readStop, unrefAfterDrain, failWrite, onUpgradeWriteClose) and confirmed each either nulls-and-calls or is a no-op once the callback has been taken, so no double invocation path was found. The _pendingData != null gate is consistent with _write (nulls it at line 2847 once the chunk reaches the handle) and with both drain handlers (null it on either outcome).

I could not run the tests in this environment (no debug build, and test execution was not permitted), so the claim that the fixtures fail on the base and pass on this branch rests on reading the code rather than on execution. The Node reference lane requires Node >= 24; the system here has v22, so on such CI hosts only the Bun lane runs.

Other factors

Both prior inline findings from this reviewer were addressed by later commits (46a274f adds finishDestroy; 7aa6ccc adds the shared harness helper), and the CodeRabbit threads were resolved by a non-author. The PR description acknowledges a remaining gap (a throw from upgraded.destroy() or terminate() when an error is set still skips the cancel tick) which pre-exists on main and is out of scope. The tests await real observable events, drain pipes concurrently, use port: 0, and gate the Linux-only RST-ordering cases with skipIf(!isLinux). Given the breadth of downstream consumers of socket teardown ordering, a maintainer familiar with the http/tls suites should still confirm the behavior change is acceptable before merge.

[claude]

Code review found no issues

No high-confidence issues detected in this change.

[claude]

Code review found no issues

No high-confidence issues detected in this change.

[claude]

Code review found no issues

No high-confidence issues detected in this change.