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node:http: convert write()/end() arguments before reading response state - #39386

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@Jarred-Sumner

@Jarred-Sumner Jarred-Sumner commented Aug 17, 2026 •

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What

node:http ServerResponse.write(chunk, encoding) / end(...): NodeHTTPResponse::write_or_end read the response state (ended / socket closed / pending), then converted encoding and the chunk (Encoding::from_js, StringOrBuffer), which can run user JS (toString / Symbol.toPrimitive) that destroys the response. It then continued into the zero-copy write path with a closed socket and a null this value (UBSan: member call on null JSCell; stock SEGV at 0x28).

write_or_end now converts all arguments first and reads the response state once, after that (this is also Node's order: write_() validates the chunk before the write-after-end / destroyed checks).

Repro (before)

import http from "http";
const server = http.createServer((req, res) => {
  const enc = Object.assign(new String("hex"), { [Symbol.toPrimitive]() { res.destroy(); Bun.gc(true); return "hex"; } });
  res.write("41".repeat(20000), enc);   // crash
  setTimeout(() => process.exit(0), 100);
});
server.listen(0, () => fetch(`http://127.0.0.1:${server.address().port}/`).catch(() => {}));

Tests

test/js/node/http/node-http.test.ts — "ServerResponse.write() with an encoding whose toPrimitive destroys the response does not crash". Fails on the ASan canary and debug main; passes here.

…d() args

Encoding::from_js / StringOrBuffer conversion can run user JS
(toString / Symbol.toPrimitive) that destroys the response. write_or_end
then continued into the zero-copy write path with a completed request
and a null this value.
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@Jarred-Sumner Jarred-Sumner changed the title node:http: re-check response state after converting write()/end() arguments node:http: convert write()/end() arguments before reading response state Aug 17, 2026
@robobun

robobun commented Aug 17, 2026 •

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Updated 9:30 PM PT - Aug 16th, 2026

✅ @Jarred-Sumner, your commit df8ca5696d615e1cfb4e600df0b1aaa02a059cff passed in Build #99838! 🎉


🧪   To try this PR locally:

bunx bun-pr 39386

That installs a local version of the PR into your bun-39386 executable, so you can run:

bun-39386 --bun

Comment thread src/runtime/server/NodeHTTPResponse.rs Outdated
Comment on lines +2284 to +2287
it.each([
["write", `result = res.write(payload, enc); res.end();`, "returned boolean"],
["end", `res.flushHeaders(); result = res.end(payload, enc);`, "returned object"],
])(

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🟡 The it.each only passes a hostile encoding to res.write()/res.end() — both route into write_or_end. Neither row sets a hostile res.statusMessage (so write_head_impl's to_bun_string at :948 stays on the is_undefined() short-circuit) and neither reaches write_informational, so reverting either of those two reorderings would not break any test in this PR (REVIEW.md: "Confirm deleting each load-bearing clause of your fix breaks at least one test"). Consider a third row, e.g. ["writeHead via statusMessage", 'res.statusMessage = enc; result = res.write("x");', "threw ERR_STREAM_ALREADY_FINISHED"], to pin the write_head_impl fix.

Extended reasoning...

What the gap is

This PR now applies the same "convert arguments before reading response state" reordering to three functions in NodeHTTPResponse.rs:

  1. write_or_end<IS_END> — the original crash fix.
  2. write_head_impl — state checks (is_requested_completed_or_ended(), SOCKET_CLOSED, raw_response, handle_ended_if_necessary) moved from :912 down to :959–978, after status_message_value.to_bun_string(global_object)? at :948.
  3. write_informational — is_done() / raw_response / handle_ended_if_necessary moved to :1251–1259, after Encoding::from_js / from_js_with_encoding_into.

The last two were added in response to the earlier "fix the whole class in the same PR" review comment. But the new it.each at node-http.test.ts:2284-2325 still only exercises the first.

Step-by-step: why neither row reaches the sibling fixes

["write", …] row: res.write(payload, enc) enters the JS write path → handle.cork(() => { handle.writeHead(this.statusCode, this[kSnapshotStatusMessage] ?? this.statusMessage, headers); handle.write(chunk, enc, …) }). The fixture never assigns res.statusMessage, so it is undefined and kSnapshotStatusMessage is unset (only set inside an explicit writeHead()). Native write_head_impl receives status_message_value = undefined, and at :946 !status_message_value.is_undefined() is false — to_bun_string() at :948 never runs, so the moved re-check at :959–978 is never the thing that observes the destroyed state. The hostile enc only fires later inside handle.write → write_or_end<false>, which is the covered path.

["end", …] row: res.flushHeaders() calls writeHead with the same statusMessage = undefined (benign), then res.end(payload, enc) sees headersSent === true and goes straight to write_or_end<true> without re-entering write_head_impl. Again only write_or_end is exercised.

Neither row calls anything that reaches write_informational (that is only entered via res._writeRaw for 1xx responses).

Why REVIEW.md flags this

REVIEW.md, Tests reviewers reject: "Every behavioral change ships an automated test in the same PR" and "Confirm deleting each load-bearing clause of your fix breaks at least one test — a test that passes both ways is worse than no test." The reordering in write_head_impl and write_informational is a behavioral change (it turns a use-of-stale-raw_response into a clean early-return/throw), but reverting either block to its pre-PR position would leave every test in this PR green.

This is not a duplicate of the existing timeline comments: the earlier sibling-site comment asked for the fix (now applied), and the earlier "cover end()" comment asked for the IS_END = true arm (now the second row). This is the remaining gap: tests for the two applied sibling fixes.

Suggested fix

The fixture already builds a hostile enc = Object.assign(new String("hex"), { [Symbol.toPrimitive]() { res.destroy(); Bun.gc(true); return "hex"; } }), so a third row can reuse it as the status message:

["writeHead via statusMessage", `res.statusMessage = enc; result = res.write("x");`, "threw ERR_STREAM_ALREADY_FINISHED"],

Trace: res.statusMessage = enc (plain data property, no validating setter in http1) → res.write("x") → handle.cork → handle.writeHead(200, enc, …) → write_head_impl :946 !is_undefined() is true → :948 to_bun_string invokes Symbol.toPrimitive → res.destroy() → abort() sets SOCKET_CLOSED and, via on_request_complete(), REQUEST_HAS_COMPLETED → back at the moved :959 is_requested_completed_or_ended() is true → throws ERR_STREAM_ALREADY_FINISHED → propagates out of cork → fixture's catch prints threw ERR_STREAM_ALREADY_FINISHED. (Confirm the exact expected string with bun bd test; if the SOCKET_CLOSED branch at :972 wins instead, the expected becomes "returned boolean" — either way the row pins the reordering.)

Covering write_informational from public API is harder (it's reached via internal _writeRaw for 1xx); if the author considers it not publicly reachable with a hostile object, saying so in the PR description satisfies REVIEW.md's "if a site is intentionally excluded, say so in the PR."

Severity

Nit. The primary crash (write_or_end) is properly tested for both write() and end(), and the two sibling reorderings are structurally identical moves of the same guard block — the risk of one being wrong while write_or_end is right is low. The PR is strictly safer than before; this only tightens the mutation-testing bar the repo's own review guide sets.

Jarred-Sumner added a commit that referenced this pull request Sep 26, 2026
…inish, lifecycle) (#43557)

One pull request for the open `node:http` server pull requests. Each
root cause is fixed once, and each pull request's tests are carried
over. Node is the reference: every scenario was run under Node and under
Bun from one script, and the outputs were compared.

Fixes #4733
Fixes #18613
Fixes #40350
Fixes #43155
Fixes #43297
Fixes #43513
Fixes #43527
Fixes #25632
Fixes #31301
Fixes #43027
Fixes #43163
Fixes #43342
Fixes #43344
Fixes #43370
Fixes #43490
Fixes #43512
Fixes #43519

Each of these has a repro that is wrong on Bun 1.4.3, right on this
branch, and the same as Node.

| Issue | Not closed by this PR, because |
| --- | --- |
| #30501 (msal-node keeps Bun alive at exit) | Probably fixed. The repro
copies the teardown of msal-node. The package itself was not run. |
| #14430 (yarn: "does not support SSL") | Probably fixed.
`response.hasOwnProperty("socket")` is now `true`. yarn itself was not
run. |
| #39681 (`server.setTimeout` callback after destroy) | Probably fixed.
The repro is the deterministic case of #39686. The script in the issue
depends on timing and on Windows. |
| #43455 (`req.complete`, nine flows) | Partially addressed. Flows 1, 2,
3, 5 and 7 are fixed, and flow 6 was already right. Flow 8 (a socket
timeout while the body of an Upgrade request arrives) and flow 9 (a
request that `stream.pipeline()` destroyed never reports `complete`) are
not. Flow 4 differs only in `_readableState.ended`. |

### What changes for users

| Area | Before | After (same as Node) |
| --- | --- | --- |
| `req.pause()` | The socket stops at once. `req.complete` stays `false`
for a small body. | The body is received until the buffer is full. Then
the socket stops. |
| `res.end()` before the body arrives | `req` gets `'end'` and `'close'`
at once, and the body is lost | The request completes when its body
really ends |
| `res.destroy()` in the middle of a body | `'end'` with bytes missing |
`aborted`, then `ECONNRESET` |
| `socket.destroy()` inside the `'request'` listener | The body that
came with the head is dropped | That body is still delivered |
| `'finish'` and the `end()` callback | Fire when `end()` buffers the
bytes | Fire when the last bytes have left the socket |
| A response that closes the connection | The server half-closes and
waits for the peer | The socket closes right behind the FIN |
| `'drain'` after a later write flushed the backlog | Lost. `pipe(res)`
could hang. | Emitted |
| A pipelined request whose body continues after the previous response
ends | Body dropped, no response, `server.close()` hangs | Delivered |
| CONNECT and Upgrade tunnel sockets | Keep reading when paused or full
| Stop reading. `_read()` starts them again. |
| A tunnel write that waits for a drain when the client goes away | Its
callback, the callbacks of the writes behind it and the `end()` callback
never run | They run with an error before `'close'` |
| Upgrade request with a body, paused in its listener | The body flows
away | The request keeps its body |
| `ws` on a reused keep-alive socket | Writes after the Upgrade could
stall | Sent |
| A raw `socket.write()` behind a response that still drains (the 400
for a bad pipelined request, the reply of a `'clientError'` listener) |
Lands in the middle of that response | Sent after it |
| `server.close()` | Could report closed while connections were open |
Waits for every connection. An idle tunnel does not keep the process
alive. |
| `closeAllConnections()` on a listening server | Also stops the
listener and destroys tunnels and WebSockets | Destroys only the HTTP
connections |
| `Proxy-Connection: close` (node:http only) | Ignored. The connection
stays open. | Ends the connection, like `Connection: close` |
| A response larger than 16 KB, also in `Bun.serve` and over TLS | Up to
4 `send()` calls for each chunk. Slower than Node in most cases. | One
write for the writes of one tick. 1.1x to 2.7x the requests per second
of main, and faster than Node. |
| `socket.destroy()` and then `res.end()` in a listener | (this PR,
earlier) `req` ended as if it were complete | `'aborted'`, then
`ECONNRESET` |
| `emit('connection')` or http2 `allowHTTP1`: the response ends while
the listener still reads the body | The rest of the body is dropped |
The body is complete |
| `httpValidation: "relaxed"`, `Content-Length` or `Transfer-Encoding`
in trailers | Accepted | `HPE_INVALID_CONTENT_LENGTH`,
`HPE_INVALID_TRANSFER_ENCODING` |
| `req.complete` inside `'connect'`, and inside `'upgrade'` without a
body | `false` | `true` |
| `optimizeEmptyRequests`: `socket.parser.incoming` after the response |
Keeps the request alive on an idle connection | `null` |
| A HEAD or OPTIONS request with `Content-Length` | The body is dropped,
and `req.complete` is `true` before it comes | The request has its body
|
| `res.end(chunk)` after the client went away | `finished` and
`writableEnded` stay `false`, no `'prefinish'` | The response ends |
| An HTTP/1.0 request with an `Expect` header | `100 Continue`,
`'checkContinue'`, `'checkExpectation'` or a 417 | A plain `'request'` |
| The idle sweep of `close()` and `closeIdleConnections()` | Could
destroy a connection that was still receiving a request, or whose
response was still draining | Closes only idle connections |

### Design

| Piece | What it is |
| --- | --- |
| Request body state | `None / Pending / Complete / Aborted / Upgraded /
Detached`. Only the last chunk sets `Complete`. One function,
`leave_pending`, is the only other way out of `Pending`. |
| Read flow control | One path: `push()` returning false stops the
socket, `_read()` starts it. Both native pause buffers are removed: no
read is copied and replayed. |
| "This read is parsed" signal | `notifyWhenReadParsed()` sets a uws
state bit. uws delivers a `readParsed` event after the read. It replaces
a `setImmediate`. |
| Close during a parse | One uws bit defers a close to the end of the
current message. |
| Response finish | A response is finished when it has ended and the
socket has fully drained. |
| Idle connection | One rule, `HttpResponse::closeIfIdle()`. A
connection is idle when it receives no request (head or body) and no
response is in flight, queued or undrained. The sweep of `close()` and
`closeIdleConnections()` both use it. |
| Idle tunnel | A tunnel at read EOF with nothing left to send. uws
reports it to the server through the connection filter (`-3`, `+3`,
`-4`). It still counts for `'close'`, but it does not hold the event
loop, like a libuv handle in that state. |
| Server `'close'` | One native close promise per `listen()`. `close()`
records whether its sweep left nothing open. Then a `listen()` in the
same tick cannot hold `'close'` back, as in
`net.Server._emitCloseIfDrained`. |
| Raw socket writes | While uws holds response bytes (its buffer, the
zero-copy tail of a `res.write()`, the cork buffer), a raw write goes
through `AsyncSocket::write`, the path a 1xx line takes. So the order on
the wire is the order of the calls. |
| Upgrade verdict | One scanner and one verdict, shared by the parser
and the dispatcher. |
| llhttp | Updated from 9.3.0 to 9.4.2, as Node v26.5.0 vendors it, plus
one local patch (see below). Node v26.5.1 and later vendor 9.4.3. That
update is not in this PR. |

The parser changes also tighten request framing so that it agrees with
llhttp in more cases. There is no new API surface.

### A pause holds from the next read

The copy of the rest of a read (`nodeHttpPausedSpill`), its replay from
a posted task and the nested parse are removed. Like in Node, the rest
of the read that caused a pause is still parsed, and the socket stops at
the next read. usockets reads up to 512 KB in one call. libuv reads 64
KB.

| One paused, unread request (client sends 64 MB) | Bytes held |
| --- | --- |
| Node 25.6 | 131,018 |
| This pull request | 524,234 |

The price is in one case. A client sends 512 KB of small pipelined
requests (19,418 of them) and never reads. Each handler answers with its
own 64 KB body:

| Handler | Runtime | Requests dispatched | RSS |
| --- | --- | --- | --- |
| Answers at once | Node 26.3 | 2,425 | +177 MB |
| Answers at once | main | 41 | +9 MB |
| Answers at once | This PR | 2,425 | +171 MB |
| Answers one tick later | Node 26.3 | 4,850 | +336 MB |
| Answers one tick later | main | 2,426 | +181 MB |
| Answers one tick later | This PR | 4,850 | +330 MB |

Release builds on Linux x64. This PR now does what Node does. main held
fewer responses, mostly for a handler that answers at once. On macOS one
read can return all 512 KB. There, Bun 1.4.3 already reached +951 MB for
the handler that answers one tick later, and Node reached +1,294 MB.
`server.maxRequestsPerSocket` bounds it.

### Performance

#### Responses larger than 16 KB are faster, and now faster than Node

On main, a response that did not fit the 16 KB uWS cork buffer released
the cork. After that, each piece was its own `send()`: the buffered
head, the chunk-size line, the data, the `\r\n` and the last chunk. Over
TLS, each 2-byte piece was also its own record. Two changes fix that,
for `Bun.serve` and for node:http:

| Change | Effect |
| --- | --- |
| A write that does not fit goes out with the cork buffer and its
framing in one vectored write | No copy is added. Over TLS, the records
of all the pieces share the write batch that one `SSL_write` loop
already had. |
| The cork buffer holds 128 KB, up from 16 KB. Only a write of 16 KB or
less is copied into it, as before. | Several writes in one tick go out
in one write, like in Node. A longer write still goes out without a
copy. |

The bytes on the wire are the same. The vectored write uses `sendmsg()`
with the flags that `send()` uses.

Write syscalls for one response:

| Response | Node 26.3 | main | This PR |
| --- | --- | --- | --- |
| 4 x `res.write(16 KB)` | 1 | 16 | 1 |
| 40 x `res.write(2 KB)` | 1 | 16 | 1 |
| `res.end(64 KB)` | 1 | 2 | 1 |
| 256 KB file, `.pipe(res)` | 4 | 16 | 5 |

Throughput (req/s, the mean of 2 rounds). Node v26.3.0, main
`97246d044e`, this PR `fe0ed1fbea`, with the method below:

| Case | Node | main | This PR | main / Node | PR / Node | PR / main |
| --- | --- | --- | --- | --- | --- | --- |
| http, 4 x `res.write(16 KB)` | 17,735 | 6,983 | 19,160 | 0.39x | 1.08x
| 2.74x |
| https, 4 x `res.write(16 KB)` | 11,720 | 6,110 | 15,510 | 0.52x |
1.32x | 2.54x |
| http, 40 x `res.write(2 KB)` | 9,879 | 6,140 | 14,980 | 0.62x | 1.52x
| 2.44x |
| https, 40 x `res.write(2 KB)` | 6,981 | 5,541 | 11,780 | 0.79x | 1.69x
| 2.13x |
| http, `res.end(64 KB)` | 18,535 | 16,528 | 19,889 | 0.89x | 1.07x |
1.20x |
| http, 256 KB file `.pipe(res)` | 2,684 | 2,375 | 2,719 | 0.88x | 1.01x
| 1.15x |
| https, `res.end(64 KB)` | 11,894 | 14,586 | 16,426 | 1.23x | 1.38x |
1.13x |
| http, GET hello (control) | 55,994 | 70,989 | 71,958 | 1.27x | 1.29x |
1.01x |

main was slower than Node in six of these eight cases. This PR is faster
than Node in all eight.

`Bun.serve`, measured on `a771572a8d`, before the larger cork buffer
(req/s, the mean of 2 rounds):

| Case | main | PR | Change |
| --- | --- | --- | --- |
| Direct stream, 4 x 16 KB | 6,826 | 12,479 | +83% |
| 64 KB string | 16,944 | 20,145 | +19% |
| TLS, 64 KB string | 15,045 | 16,892 | +12% |
| hello (control) | 83,957 | 83,137 | -1.0% |

These runs are on loopback, where the kernel send buffer is 2.6 MB and
the work of the receiver runs inside `send()`. That is the best case for
fewer writes. A new connection over a real network takes about 46 KB in
its first write on Linux. The rest waits in the socket buffer, as it
would after separate writes.

#### Small responses are unchanged

A small response is already one `recvfrom` and one `sendto` on both
builds. `perf` puts 66% of the time of a hello-world server in the
kernel, on both builds.

CI release builds on Linux x64: main `97246d044e` (the merge base)
against this PR `8834cd0787`. Both use the same WebKit. The server runs
on one pinned core. `oha` sends 64 connections for 5 s after a 2 s
warm-up. There are 2 rounds, and the order of the builds alternates.
"Change" compares the means of the two rounds.

Framework servers from `bun-perf-tester` (req/s):

| Server | main, round 1 | main, round 2 | PR, round 1 | PR, round 2 |
Change |
| --- | --- | --- | --- | --- | --- |
| express | 49,803 | 51,103 | 49,968 | 50,263 | -0.7% |
| fastify | 61,214 | 61,105 | 60,705 | 60,668 | -0.8% |
| node:http | 70,934 | 71,405 | 73,178 | 71,053 | +1.3% |
| elysia | 84,696 | 85,096 | 85,027 | 84,882 | +0.1% |
| `Bun.serve` | 89,020 | 89,099 | 88,168 | 88,373 | -0.9% |

node:http paths that this PR changes (req/s):

| Case | main, round 1 | main, round 2 | PR, round 1 | PR, round 2 |
Change |
| --- | --- | --- | --- | --- | --- |
| GET hello | 70,226 | 70,341 | 70,151 | 72,359 | +1.4% |
| POST, 16 KB body | 47,446 | 47,789 | 48,191 | 48,785 | +1.8% |
| 64 KB response in four writes | 6,885 | 6,894 | 6,834 | 6,868 | -0.6%
|
| Pipelined keep-alive, depth 8 | 94,063 | 93,294 | 92,909 | 93,809 |
-0.3% |

p99 latency (ms), the higher of the two rounds:

| Server | main | PR |
| --- | --- | --- |
| express | 1.94 | 1.91 |
| fastify | 1.52 | 1.55 |
| node:http | 1.11 | 1.12 |
| elysia | 0.98 | 0.96 |
| `Bun.serve` | 0.82 | 0.83 |

RSS (MB), one pass of 8 s of load:

| Server | Build | Start | Under load | 5 s idle | 15 s idle |
| --- | --- | --- | --- | --- | --- |
| express | main | 39 | 94 | 61 | 57 |
| express | PR | 40 | 92 | 60 | 57 |
| fastify | main | 41 | 91 | 58 | 55 |
| fastify | PR | 41 | 91 | 58 | 55 |
| node:http | main | 20 | 64 | 43 | 40 |
| node:http | PR | 20 | 65 | 45 | 41 |
| elysia | main | 28 | 46 | 36 | 35 |
| elysia | PR | 29 | 46 | 37 | 36 |
| `Bun.serve` | main | 14 | 30 | 22 | 22 |
| `Bun.serve` | PR | 14 | 30 | 22 | 22 |

Every change is within 2%. fastify and `Bun.serve` hello are lower in
both rounds, by about 1%. `Bun.serve` hello shows the same -1.0% in the
control row above, so a small real cost there is possible. The RSS pass
ran at the same time as the throughput runs, on other cores. The commits
after `8834cd0787` change tests and add one version check to the
node:http dispatcher. They were not measured.

### Supersedes

| Theme | Pull requests |
| --- | --- |
| Request body | #43592 #43579 #38196 #43518 #43602 #43408 #43427 #43597
#43555 #43456 #43466 |
| Tunnels | #43570 #43485. #43596 is a duplicate of #43570. |
| Parser | #43182 #43161 #43326 #43327 #40505 #43363 #42532 #42194 |
| Response write | #39386 #43371 #43548 #43499 #43496 #43464 #42008
#43549 |
| Response finish | #40351 #43021 #41822 #43473 #42068 #35207 #43425
#43503 |
| Lifecycle | #43413 #39686 #43028 #42727 #42622 #42610 #35837 #35839
#37825 #37749 #43376 #35268 |
| JS API | #41691 #41738 #38036 #42462 #36527 #39718 #37964. #42947
merged on its own. |

The close drain, `resetAndDestroy()`, the pending write callback
handling and the response `'close'` ordering come from #42622 and #42727
by @steipete. The diagnosis and the tests for the stalled `ws` writes
come from his #42610.

Not included:

| Pull request | Reason |
| --- | --- |
| #33061 | main already enforces `headersTimeout` and `requestTimeout` |
| #41672 | It makes `http.createServer({ key, cert })` stop serving TLS.
That needs a product decision. |
| #37543 | A type refactor with no tests and no user-visible change |
| #35465 | It makes `http.Server` extend `net.Server`. Only the
prototype chains were joined. The `net.Server` constructor never ran, so
`_handle` and `_connections` were `undefined`, and
`_emitCloseIfDrained()` emitted `'close'` on a listening server. The
server is backed by uWS, not `node:net`. |
| The `AutoFlusher` removal in #42622 | It makes `flushHeaders()` flush
at once. That is a performance change with no relation to the rest. |

### Tests

| Check | Result on a debug build (macOS arm64) | Head |
| --- | --- | --- |
| Every test file that this PR touches (28 files) | 1,866 pass, 2 fail.
The 2 failures are `serve.test.ts` "bounds memory when proxying ... to a
stalled client". They fail the same way on a debug build of main. |
`83af4da4a3`, run before the last commit of main came in |
| `test/js/third_party/express` (9 files) and the `body-parser` test |
299 pass, 0 fail | `83af4da4a3`, run before the last commit of main came
in |
| Node 25.6 against Bun, 32 scenarios from two scripts (event order,
framing, lifecycle) | No regression against Bun 1.4.3 | `0ff1a23f61` |
| Every vendored Node `test-http-*` and `test-https-*` file, plus the
`test-net-*` and `test-tls-*` files for pause, write, end and close |
535 of 537 exit 0. `test-http-agent-keepalive.js` and
`test-https-timeout.js` fail on that debug build. Both pass on every CI
lane. | `daee05fcfd` (before the rebase) |
| The tests that depend on what the kernel takes in one send, on Windows
Server 2019 x64 and Windows 11 arm64 | pass | `3eef223328` (x64),
`a29289bcc1` (arm64) |
| CI build 120191 (Linux, macOS and Windows, release and ASAN) | every
lane passed | `daee05fcfd` (before the rebase) |

Each new test fails on Bun 1.4.3, or on the commit before its fix for a
fault that this branch introduced.

The two tests over the limit are `node-http-connect.test.ts` ("tests
should run on bun") and `node-http-syscall-fault.test.ts` ("racing a
queued drain"). Each starts a debug subprocess that needs more than 5 s
on this machine. Both pass on CI.

### Changes in the last push

The branch is rebased on main (`daee05fcfd` was the head before). It is
now linear.

Four regressions against main, each with a test that fails without its
fix:

| Case | main | Before this push | Now (same as Node) |
| --- | --- | --- | --- |
| `emit('connection')` or http2 `allowHTTP1`: `res.end()` on a request
that nobody reads | `'end'`, `'close'` | No events | `'end'`, `'close'`
|
| The same server, an unread 32 MB body | 0 bytes held | 32 MB held | 0
bytes held |
| A NUL in a header value with `httpValidation: "relaxed"` (client,
`HTTPParser`, `emit('connection')` server) | Accepted | The process
spins forever | `HPE_INVALID_HEADER_TOKEN` |
| `Connection: close`, body in the same read as the head, a 20 KB
response before the body is read | `'end'` with an empty body | No
events on `req` | `'end'` with the body, `'close'` |
| An empty line on an idle keep-alive connection, then `server.close()`
| 0 s | About 6 s | 0 s |

| Fix | Where |
| --- | --- |
| The finish listener of a fallback connection dumps an unread request,
like Node's `resOnFinish` | `http1_server_fallback.ts` |
| llhttp patch: `llhttp__internal__c_test_lenient_flags_20` is false for
a NUL. The relaxed state does not consume a NUL, and the next state sent
it back there. 9.4.3 has the same loop. | `llhttp.c`, noted in its
`README.md` |
| A node:http socket that `onData` is parsing gets the close gate of
`onData`, also when a large write released the cork | `HttpResponse.h`
`uncorkCompletedResponse()` |
| A read that starts no message leaves an idle connection idle |
`HttpContext.h` `onData` |

The open review threads are fixed in `8834cd0787`:
`closeAllConnections()`, `Proxy-Connection: close`, five comments cut to
one line, and the test of two overlapping listeners, which now waits on
events. With the generation gate in `emitCloseServer` removed, that test
fails in both cases. `AsyncSocketData` keeps its bools together, which
takes it from 56 to 48 bytes per socket.

`http.Server` no longer extends `net.Server` (see "Not included"). The
special case for it in `Ipc.ts` is gone too. `child.send(msg,
httpServer)` still throws `ERR_INVALID_HANDLE_TYPE`, and its test stays.

<details><summary>Changes since the first revision (2988a61)</summary>

Merged with main at `c8e1f6fa5b`. The one conflict was #43708
(`req.socket` emits `'end'` and `'error'`). Its state bit
`HTTP_NODE_PEER_ENDED` moved to bit 22, because bit 19 is
`HTTP_NODE_NOTIFY_READ_PARSED` here. Its 15 tests run in
`node-http-server-abort-events.test.ts` next to the tests of this branch
(103 pass).

CI on `2988a610c` had ten red tests from four causes. They are fixed:
- `ed882e5e99`: `write()` to a response without a body (HEAD, 204) does
not wait for unsent bytes.
- `811f817704`: an idle tunnel does not hold the event loop after
`server.close()`. Four vendored Node tests timed out on every platform.
- `0697deec11`, `d428824c08`, `7aec062d14`: the write callback tests use
a body that backs up a loopback socket, and accept what Winsock does.
- `c7af1c1615`: two tests from main asserted the old `close()` contract.

Review findings, each reproduced against Node v26.3.0 and fixed with a
test that fails without the fix:
- `d4d2b783ea`, `2cc79939bb`, `45141abca9`, `9a63dbc470`, `80a23a1822`:
the idle rule. A keep-alive connection is idle again when its body ends
after its response. A connection that owes a queued pipelined response,
that still receives a request head or body, or whose response still
drains is not idle.
- `87d8904aa3`, `7eca4f7806`: `close(cb)` followed by `listen()` in the
same tick reports `'close'`, also for an https server whose only
connection was idle.
- `3fd7b25382`: a paused pipelined request behind a response that still
drains stops the connection. The first revision read 512 MiB of 512 MiB
into memory.
- `2d1a5e2d8d`, `33e4683a8a`, `539cb41eb9`, `197c7dfc29`, `0490e3540b`:
raw socket writes stay behind every unsent response byte. The cases were
a CONNECT pipelined behind a response that still drains (its `200`
landed at offset 2.6 MB of a 64 MiB body), a zero-length tunnel write
(it hung the tunnel), the 400 replies above, the zero-copy tail of a
large `res.write()`, the cork buffer, and Windows 11, where the kernel
takes the whole response and refuses the next send.
- `0abd39c133`: an upgrade from the request's `'end'` listener keeps the
body bytes out of the WebSocket. The connection closed with 1006 right
after the 101.
- `5aafc61aa6`: the callback of a small `res.write()` that the kernel
refuses at the uncork runs on the drain. Reproduced on Windows 11 only.
- `a29289bcc1`: a tunnel write that waits for a drain settles its
callbacks when the connection closes.

Known differences from Node that this PR leaves:
- A handler that calls `res.end()` and then `server.close()` closes its
keep-alive connection at once. Node waits for the `keepAliveTimeout`.
- A pipelined Upgrade behind a response that still drains is served as a
plain request.
- An `end()` on a tunnel with no write pending, while the response
before the CONNECT still drains, closes both directions after the flush.
Node half-closes.
- A raw `req.socket.write(big)` and `req.socket.end()` with no
`res.end()` sends every byte but no FIN. main loses bytes here.
- A CONNECT socket that is given back with `server.emit('connection',
socket)` answers only the first of several pipelined requests. main
answers none.
- A large write from an `'upgrade'` listener stalls while the body of
that Upgrade request is still pending. A second `listen()` on a
listening server does not throw. Both are the same on main.
- A tunnel write that fails because the client went away fails its
callbacks but emits no `'error'`. Node emits `ECONNRESET`. A new
`'error'` could end a process that has no listener for it.

</details>

<!-- robobun:evidence:begin -->

---

**no test proof** · iteration 8 · platform-specific test(s) that do not
run on this machine, deferring to CI, which covers all platforms:
test/js/web/fetch/fetch.stream.test.ts, test/js/node/url/url.test.ts,
test/js/node/tls/tls-syscall-fault.test.ts,
test/js/node/net/node-net-server.test.ts,
test/js/node/http/node-http.test.ts,
test/js/node/http/node-http-syscall-fault.test.ts,
test/js/node/http/node-http-server-close-drain.test.ts,
test/js/node/http/node-http-connect.test.ts,
test/js/node/http/node-http-backpressure.test.ts,
test/js/node/child_process/child_process_ipc_handle.test.ts,
test/js/bun/http/serve.test.ts,
test/js/bun/http/serve-syscall-fault.test.ts,
test/js/bun/http/bun-server.test.ts

<!-- robobun:evidence:end -->

---------

Co-authored-by: Jarred Sumner <jarred@jarredsumner.com>
Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
@Jarred-Sumner

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Superseded by #43557, which is merged (5d5f03f). It fixes this once for the whole node:http server and carries the tests over.

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