Skip to content

node:http: dispatch a CONNECT whose header block arrives in a later read - #43161

Closed
robobun wants to merge 2 commits into
mainfrom
robobun/723408de/connect-split-head
Closed

robobun wants to merge 2 commits into
mainfrom
robobun/723408de/connect-split-head

Conversation

@robobun

@robobun robobun commented Sep 17, 2026 •

Copy link
Copy Markdown
Collaborator

Problem

  • A node:http server never answers a CONNECT whose header block arrives in a later read than its request line. 'connect' never fires, nothing is sent, and the connection stays open. Regression from node:http/https/http2: raise Node v26.3.0 compat to ~94%, sync the upstream suites, and fix the Windows/macOS transport-layer teardown bugs they exposed #32488 (1.4.0).
  • Cause: getHeaders (packages/bun-uws/src/HttpParser.h:983) set isConnectRequest when the request line parsed. On the next read, the tunnel check in fenceAndConsumePostPadded (HttpParser.h:1144) passed the rest of the head to the data handler as tunnel bytes.
  • The early flag also exempts a CONNECT that was never dispatched from headersTimeout and from the EOF handling in onEnd (HttpContext.h:915). A parsed head that fails a framing check does the same.

Fix

  • fenceAndConsumePostPadded sets isConnectRequest immediately before it calls the request handler. getHeaders only reports the CONNECT request line.
  • Correct because a connection is a tunnel only after its CONNECT is dispatched. Until then the bytes are HTTP, so the fallback buffer, headersTimeout, and the EOF handling apply.
  • Bun.serve does not change. The tunnel check is node:http only.
  • Verified: test/js/node/http/node-http-connect.test.ts (6 new tests, each times out without the fix, expectations match Node v26.3.0). The Notes list the other suites.

Background

  • uWS parses each socket read (one recv()) in consumePostPadded. An incomplete head goes to a per-connection fallback buffer. The next read is appended, and the head is parsed again from the start.
  • isConnectRequest is a per-connection flag. It marks a CONNECT or Upgrade tunnel: the parser passes all later bytes to the JS socket unparsed.
  • A client that writes the request line and the headers separately produces two reads.
Notes

Repro. http.createServer() with a 'connect' listener. The client writes CONNECT example.test:443 HTTP/1.1\r\nHost: example.test:443\r\nProxy-Connection: keep-alive\r\n\r\n in two segments, cut at every offset (90 offsets, the request line ends at offset 35).

answered
Node v26.3.0 90 of 90
Bun 1.3.14 89 of 90 (offset 7 gets a 505, a separate bug that is fixed on main)
main 1..35 only. At 36..90 nothing is received and the connection is left open
this branch 90 of 90

With no 'connect' listener Node closes the connection at every offset. main closes at 1..35 and leaves 36..60 open. This branch closes at 60 of 60. The Upgrade and plain GET controls do not change. The hang starts at offset 36 because consumeRequestLine reports a short read until one byte follows the request line's CRLF.

Why 1.3.14 worked. The early latch is older (#22756). It was harmless until #32488 added the node:http tunnel check at the top of the parse loop (for an Upgrade request with a body). After that, the second read of a split CONNECT head takes the tunnel branch before getHeaders runs again.

The other symptoms, same cause. In each one the flag is set for a CONNECT that was never dispatched, so no tunnel socket exists.

  • isRequestTimedOutImpl (src/jsc/bindings/node/JSNodeHTTPServerSocket.cpp:288) returns false when isConnectRequest is set. A client that sends CONNECT host:443 HTTP/1.1\r\nHost: host:443\r\nX-Slow: and stops is never swept. Node answers 408 Request Timeout and closes. A GET with the same partial head gets the 408 on main.
  • onEnd returns early for a tunnel. A client that sends a partial CONNECT head and then FIN gets no 'clientError', and the server never closes the connection (getConnections still counts it). Node reports HPE_INVALID_EOF_STATE.
  • Found in review: a CONNECT head that parses and then fails a framing check (two different Content-Length values give HPE_UNEXPECTED_CONTENT_LENGTH on Node and on Bun). With a 'clientError' listener that leaves the socket open, main never closes the connection after the client's FIN. Node closes it, and main closes it for a GET with the same headers. The first commit moved the latch to the point where the head is complete, which did not cover this. The second commit moves it to the dispatch.

Readers of isConnectRequest that I checked.

  • HttpParser.h tunnel check and the remainingStreamingBytes branches in consumePostPadded: wrong before the dispatch (this bug), unchanged after.
  • HttpParser.h Host header exemption: now reads the per-request flag from getHeaders. A stale connection flag cannot reach it, because a tunnel never gets to getHeaders again.
  • NodeHTTPResponse.rs (pause_socket, resume_socket) reads the flag while the handler runs, so the latch is before the handler call, not after it.
  • HttpContext.h onData: the HTTP_NODE_PARSING_STOPPED gate and trackNodeHttpTimings. An error in a CONNECT head now stops further parsing like any other request.
  • HttpContext.h onClose, onWritable, the data handler: no-ops until the request is dispatched (socketData and inStream are null).
  • Bun.serve (IsNodeHttp = false): the tunnel check is compiled out. A split CONNECT head answers the same before and after.

Tests. The split tests need the two parts to reach the parser in two reads, and a partial head emits nothing on the server. Two ways to sequence it without a timer:

  • New connection: after the first part, a whole request on a second connection is the barrier. The server has read the first part by the time it has answered and closed that connection.
  • Same connection: the first write is a whole GET plus the first part of the CONNECT head. The response to the GET leaves after the server has parsed the whole read.

The second part also carries bytes after the head (tunneled). They arrive as the head argument of 'connect', like Node.

Also checked by hand against Node v26.3.0: the head written one byte per read and seven bytes per read, over http and https, followed by tunnel bytes in two more writes. This branch matches Node. main hangs.

Suites run with the debug build. node-http-connect.test.ts, node-http-server-timeouts.test.ts, node-http-transfer-encoding.test.ts, test/js/bun/http/request-smuggling.test.ts, and from test/js/node/test/parallel: test-http-connect.js, test-http-connect-req-res.js, test-http-eof-on-connect.js, test-http-after-connect.js, test-http-parser-freed-before-upgrade.js, test-http-server-request-timeout-upgrade.js, test-http-proxy.js, the four test-http-server-headers-timeout-*.js, test-http-upgrade-server.js, test-http-upgrade-server2.js, test-http-upgrade-server-with-body.mjs, test-http-upgrade-server-with-body-and-extras.mjs, test-http-upgrade-binary.js, test-http-upgrade-reconsume-stream.js. All pass. One exception in node-http-connect.test.ts: under a debug build, tests should run on bun times out at 5 s because its sub-suite takes about 6.5 s. It does the same without this change.


no test proof · iteration 0 · platform-specific test(s) that do not run on this machine, deferring to CI, which covers all platforms: test/js/node/http/node-http-connect.test.ts

getHeaders latched isConnectRequest as soon as the CONNECT request line
parsed. When the header block arrived in a later read, the tunnel check
at the top of the parse loop saw the flag and passed the rest of the
head to the data handler as tunnel bytes. The 'connect' event never
fired and the connection stayed open. The same early latch exempted a
partial CONNECT head from headersTimeout and from the EOF handling
(HPE_INVALID_EOF_STATE).

Latch isConnectRequest only after getHeaders returns a complete head.
@coderabbitai

coderabbitai Bot commented Sep 17, 2026 •

Copy link
Copy Markdown
Contributor

Warning

Review paused — included plan limit reached

Keep your review moving with free on-demand reviews.

  • Run this review for free

On-demand reviews are free for the next 3 days.

  • Ask an admin to make reviews automatic

Open in CodeRabbit

Reviews can continue after your included limit without a manual trigger. An admin must approve usage-based billing.

Promotion and pricing details

On-demand reviews are free for the next 3 days. After that, they cost $0.25 per reviewed file.

Review limit details

Or wait 2 minutes for your next included review.

Check out review usage here.

Limit details: You’ve used all 10 included reviews currently available.

Learn how review limits work.

Review configuration:

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Essentials

Run ID: 84e61211-244f-4560-b6e5-1d15fd171102

📥 Commits

Reviewing files that changed from the base of the PR and between fd8422c and a5737fc.

📒 Files selected for processing (2)
  • packages/bun-uws/src/HttpParser.h
  • test/js/node/http/node-http-connect.test.ts

Comment @coderabbitai help to get the list of available commands.

@robobun

robobun commented Sep 17, 2026 •

Copy link
Copy Markdown
Collaborator Author
Updated 3:53 PM PT - Sep 17th, 2026

✅ @robobun, your commit a5737fc0f6b703647581b524b3b07ecab4aab728 passed in Build #117309! 🎉


🧪   To try this PR locally:

bunx bun-pr 43161

That installs a local version of the PR into your bun-43161 executable, so you can run:

bun-43161 --bun

@robobun

robobun commented Sep 17, 2026 •

Copy link
Copy Markdown
Collaborator Author

Status: closed. Superseded by #43557, merged as 5d5f03f. The tests from this PR are on main.

How I reproduced it:

  1. Start http.createServer() with a 'connect' listener that answers HTTP/1.1 200 Connection Established.
  2. From a net client, write CONNECT example.test:443 HTTP/1.1\r\nHost: exa. Wait until the server has read it. Then write the rest of the head.
  3. Before the fix the 'connect' event never fires, the client receives nothing, and the connection stays open. Node v26.3.0 answers with the 200.

On main at 5d5f03f the same steps get the 200, and the 6 tests under before the CONNECT is dispatched in test/js/node/http/node-http-connect.test.ts pass.

@claude claude Bot left a comment

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

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

Beyond the inline finding, I also checked the writeInTwoReads barrier in test/js/node/http/node-http-connect.test.ts for a coalescing race: client and server share one event loop thread and first is written before the barrier's connect, so the server has consumed first before the barrier's close callback can issue second — the split-head tests cannot pass by accident. I also checked Bun.serve: the tunnel check is IsNodeHttp-only, and the remaining readers of isConnectRequest (Host exemption, onData timing/parsing-stopped gate, onClose/onWritable) run after getHeaders succeeds, so moving the latch after consumed != 0 does not change their inputs.

Extended reasoning...

One confirmed finding is posted inline, so the review body is limited to the concrete concerns examined and ruled out. The barrier-connection ordering in the new test helper was the main timing assumption a reviewer would question; it holds because the test's client and server run on the same single-threaded event loop and the first fragment is written before the barrier socket exists, so the server cannot see first and second in one read. The parser change itself is small (rename of the out-parameter, unconditional per-request-line write, latch moved after the complete-head check) and its non-node:http readers were traced to run after dispatch, which is why the Bun.serve path is unaffected.

One verified lower-impact observation (a convention, logging or cleanup point) was not posted.

Comment thread packages/bun-uws/src/HttpParser.h Outdated
A CONNECT head that parses but fails a framing check (for example two
different Content-Length values) returned an error with isConnectRequest
already set and no 'connect' dispatch. With a 'clientError' listener that
leaves the socket open, onEnd then treated the connection as a tunnel
with no socket and never closed it after the client's FIN.

Set isConnectRequest immediately before the request handler runs, so no
error return can leave the flag set for a CONNECT that was not
dispatched. The Host exemption reads the per-request flag.

@claude claude Bot left a comment

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

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

The latest push moves the latch to the dispatch point (HttpParser.h:1337), which is what the earlier inline comment asked for, and the split-CONNECT tests now cover the timeout, EOF and failed-framing paths. Beyond the inline findings, I also checked: no reader of the connection-level isConnectRequest sits between the getHeaders return and the new latch (the Host exemption at :1303 is the only pre-dispatch consumer and now reads the per-call flag); both fenceAndConsumePostPadded call sites (:1532 fallback and :1614 direct) share the same reference, so a head completed out of the fallback buffer latches at the same point; and an Upgrade-with-body tunnel latched from HttpContext.h:625 is unaffected because that connection takes the tunnel branch at the loop top before getHeaders runs.

Extended reasoning...

The diff is a two-line semantic change in packages/bun-uws/src/HttpParser.h (per-call isConnectRequestLine out-param written unconditionally, connection-level isConnectRequest latched only immediately before requestHandler) plus six new node:http tests. I traced every reader of the connection-level flag (parser tunnel checks at :1141/:1464/:1549, HttpContext.h :253/:378/:397/:604/:611/:619/:814/:915, and the timeout sweep) and confirmed each runs either before getHeaders on a later read or after dispatch, so the only behavioral change is that a never-dispatched CONNECT no longer looks like a tunnel. The two posted findings are pre-existing behaviors at the dispatch site (pipelined-behind-pending-response and non-chunked Transfer-Encoding on CONNECT), so a human should weigh whether they belong in this PR; the ruled-out list this run contained only duplicates of those findings, and the items above come from my own reading of the diff.

Comment thread packages/bun-uws/src/HttpParser.h
Comment thread packages/bun-uws/src/HttpParser.h
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

Copy link
Copy Markdown
Collaborator

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

@robobun

robobun commented Sep 26, 2026

Copy link
Copy Markdown
Collaborator Author

Confirmed on main at 5d5f03f with a debug build. Nothing from this PR is left to land.

  • The reproduction from the report answers at every cut. connect gets the 200 at 90 of 90 offsets. connect-nolistener is closed at 60 of 60.
  • The 6 tests from this PR are on main in test/js/node/http/node-http-connect.test.ts, under before the CONNECT is dispatched. All 6 pass.
  • The two cases from the review threads here also match Node v26.3.0 on main. A CONNECT pipelined behind a pending response gets 'connect' and its tunnel bytes. A CONNECT with Transfer-Encoding: gzip gets 'connect' and no 'clientError'.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Labels

Projects

None yet

Development

Successfully merging this pull request may close these issues.

2 participants