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…Parser With insecureHTTPParser (llhttp LENIENT_TRANSFER_ENCODING), a request whose Transfer-Encoding does not end in chunked has no body framing. llhttp reads the body until the client closes the connection and raises no error. The parser rejected such a request after dispatch (gzip), or framed a coding after chunked as no body at all and parsed the body bytes as the next request (chunked, gzip). The lenient chunked verdict is now the last list element's, like llhttp. A lenient request with no chunked final coding and no Content-Length puts the parser in a body-until-EOF mode: every later byte is body, and onEnd delivers the fin. Strict node:http and Bun.serve do not change.
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Updated 6:46 PM PT - Sep 18th, 2026
✅ @robobun, your commit 484f1caf972f4463f9731f28f201e77153f6c666 passed in 🧪 To try this PR locally: bunx bun-pr 43363That installs a local version of the PR into your bun-43363 --bun |
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Nothing blocking. The comments below are optional suggestions. There is no need to push a fix for them before merging.
Beyond the inline findings, I also checked that the new transferEncoding.chunked = lenientChunked override and the body-until-EOF mode cannot reach Bun.serve: useLenientTransferEncoding is only set through Server__setAppFlags (NodeHTTP.cpp, node:http's setFlags), and every new branch in consumePostPadded/fenceAndConsumePostPadded is additionally gated on IsNodeHttp. The new fallback path's success(0, ...) return after handing the remainder to dataHandler matches the existing remainingStreamingBytes convention on the same path.
Extended reasoning...
Findings are posted inline, so this body only records what else was examined. The PR description claims strict node:http and Bun.serve are unchanged; I traced useLenientTransferEncoding from HttpContextData.h through App.h::setFlags to its sole caller in src/jsc/bindings/NodeHTTP.cpp (Server__setAppFlags), confirming Bun.serve contexts never set it, and confirmed the new nodeHttpBodyUntilEof branches in consumePostPadded (direct and fallback) and the bodyUntilEof branch in fenceAndConsumePostPadded are all gated on IsNodeHttp. The removed return te statements in getTransferEncoding only change control flow when te.invalid is already set, which strict mode still rejects, so strict behaviour is preserved. The change is a parser behaviour change on a security-sensitive path (request framing), so a human look at the inline findings remains worthwhile.
…rade under the lenient parser
string_view::rfind in HttpParser.h now reaches the MSVC STL vectorized find_last. It is gated behind __isa_available like the other STL entries. The inner template form was already listed; this toolchain records the exported flat name.
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CI on ce67791: 180 of 181 jobs pass. The one red job is |
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One security regression from #43344 still looks worth pinning explicitly in this PR. The new EOF-body tests prove that raw bytes (including chunk-looking bytes) are delivered as the first request's body, but I don't see a case where those bytes are themselves a syntactically valid HTTP request. That distinction is useful because the original failure mode was exactly that body bytes could become the next request line. I'd add one negative control under then FIN the client. Assert:
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…hed as a second request
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Good point, added in 7e6c163: under insecureHTTPParser with |
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Inline comments:
In `@packages/bun-uws/src/HttpContext.h`:
- Around line 935-949: Update HttpContext<SSL>::onEnd so EOF is recorded when
nodeHttpBodyUntilEof is active but inStream is null, ensuring
NodeHTTPResponse::body_read_state transitions to Done and a later _read observes
the terminal state without waiting for a callback. Preserve the existing
callback behavior when inStream is present.
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…ll ends the request
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In `@test/js/node/http/node-http-transfer-encoding.test.ts`:
- Line 1053: Update the FIN-before-reader test around the setImmediate callback
to install a connection-level end listener when the server accepts the
connection, await that end event before attaching request body listeners, and
remove reliance on setImmediate or a single client socket.end() call for
ordering. Preserve the test’s intended EOF-before-reader scenario.
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…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>
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Problem
insecureHTTPParser: truegets a request whose Transfer-Encoding does not end inchunked.gzipgives an empty body andclientError HPE_INVALID_TRANSFER_ENCODING.chunked, gzipis framed as no body, so the body bytes parse as the next request line. Node v26.3.0 reads the raw body until the client closes the connection.getTransferEncoding(packages/bun-uws/src/HttpParser.h:362) returned before it sethasfor a coding afterchunked.fenceAndConsumePostPadded(line 1298) raised the deferred error in lenient mode too. The parser had no body mode besides chunked and Content-Length.Fix
getTransferEncodinggainslenientChunked, llhttp's lenient verdict: the last list element of the last non-empty field (chunked, chunkedis chunked,chunked, gzipis not).nodeHttpBodyUntilEof. Every later byte is body.HttpContext::onEnddelivers the fin at the client's FIN, like Node'sparser.finish(). A CONNECT or Upgrade request never enters the mode.llhttp__after_headers_completereturns 4 (body until EOF) under that flag. Strict node:http, Bun.serve, and the TE plus Content-Length rejection do not change.test/js/node/http/node-http-transfer-encoding.test.ts(23 new tests, 15 fail without the fix). Alsorequest-smuggling.test.tsand all oftest/js/node/http/. Self-reviewed: 9 concerns raised, 4 addressed, see Notes.Background
useLenientTransferEncodingis llhttp'sLENIENT_TRANSFER_ENCODINGbit, set byinsecureHTTPParser: trueandhttpValidation: "insecure"only.remainingStreamingBytesstate, so a FIN in it is notHPE_INVALID_EOF_STATE.Notes
llhttp verdicts (Node v26.3.0,
HTTPParserfromnode:_http_common, kLenientAll, body bytes5\r\nHELLO\r\n0\r\n\r\n). Body until EOF:gzip,identity,chunkedchunked,chunked, gzip,chunked,,chunked, ,, achunkedfield then agzipfield,chunkedthen an empty field thengzip. Chunked (bodyHELLO):chunked, chunked,chunked , chunked,chunked, gzip, chunked, twochunkedfields,chunked, gzipthen achunkedfield,chunkedthen an empty field,gzip, chunked. The test table mirrors this.Self-review. Addressed: the mode is gated off for CONNECT and Upgrade requests (an accepted upgrade would otherwise wait for a body that ends only at the FIN); the tests set
server.httpAllowHalfOpen = trueas a property, which is what Node reads (the createServer option is not a Node option); the TE plus Content-Length test is labelled as Bun's stance, not Node parity; the describe header no longer claims every expectation is Node's. Not taken: a split into a fail-closed parser PR plus a later body-until-EOF PR stacked on #43326. The issue asks for the body until EOF, the two parts are small, and the Upgrade gate removes the ordering hazard between the two diffs. The onEnd fin delivery is not factored into a helper shared with the onData lambda: the lambda also handles tunnels and the pause bookkeeping, and the fin here is one call.Out of scope, noted for the reader.
res.end()runs before the body is consumed, even with a'data'listener (node:http: keep receiving the request body after the response has ended #38196 covers it). This is independent of Transfer-Encoding: a plain chunked POST withreq.on("data", ...)and a synchronousres.end()getsbody=""on main. The issue's repro uses that pattern, so after this fix it printsbody=""with noclientError. The tests here respond after'end'withserver.httpAllowHalfOpen = true, the shape Node needs too.LENIENT_CHUNKED_LENGTH) and reads until EOF. Bun implements onlyLENIENT_TRANSFER_ENCODING(HttpContextData.h) and keeps rejecting that pair. Unchanged here.Data flow of the new mode.
fenceAndConsumePostPaddedsetsnodeHttpBodyUntilEofafter the request handler and, when not consuming minimally, hands the rest of the read to the data handler.consumePostPaddedchecks the flag beforeremainingStreamingBytes, on the direct path and on the fallback path (head completed across reads).onEndclears the flag, resets the per-message timeout bookkeeping, and callsinStreamwithfin = true, the same call the data handler inonDatamakes for a chunked body's last chunk.[human-review] gate passed · iteration 3 · 4 files touched
fails on main (without fix)
passes on PR (with fix)
diff hotspot
gate history · 4 passed · 0 rejected · iteration 3
evidence per changed file
root cause · written by the author bot
In the lenient parser mode, the uWS HTTP parser had no "read body until EOF" path for requests, so a Transfer-Encoding that did not end in
chunkedwas either rejected after dispatch (the deferred error ignoreduseLenientTransferEncoding) or, for a coding afterchunked, treated as no Transfer-Encoding at all becausegetTransferEncodingreturned before settingte.has, letting the body bytes be parsed as the next request line. The fix makesgetTransferEncodingrecord the header's presence before returning, suppresses the deferred error when lenient Transfer-Encoding is on, and adds…